The Story of Cosmology: The Big Bang, Dark Matter, Dark Energy & the Great Mysteries of the Universe

foreign is finite but the unknown infinite intellectually we humans stand in the midst of an illimitable ocean of inexplicability our business in every generation is to reclaim a little more land [Music] thank you very much [Music] in the first instant of time all of existence was intertwined fields of near Infinite Energy particles didn't exist matter didn't exist everything was fluid unified and energies like this haven't been seen in the universe anywhere ever since [Music] less than a trillion trillionths of a second later in an already expanding Universe an additional event called inflation happened under the influence of what cosmologists cleverly called the inflaton particle the metric of space-time itself suddenly stretched exponentially in these overlapping energy Fields began evolving into the physics we know today before this inflation this observable universe our local pocket of the universe was only the size of half the width of a proton inflation banded this to 10 to the power of 78 times this volume so this is a huge order of magnitude and let's put it on more human scales here our volume of space went from about the size of a proton plated to a grain of sand but even that doesn't do it justice most of us don't have an intuition of just how small the quantum realm is myself included so I think a better visualization to the picture to the tune of something more anthropomorphic more human centered would be still something really small microscopically small but still imaginable like a plant cell and this is about a 50th of the width of a human hair or about a thousandth of a millimeter under this same scale of inflation that plant cell would have ballooned to ten thousand light years across then to put that in even further context that ten thousand year light your chunk of our Milky Way galaxy holds about 350 000 Stars but because the universe really was only the size of a proton before inflation at Scales like this well within the quantum realm of things tiny fluctuations in the quantum field energy are always randomly bubbling in and out of existence and these came into play it's believed that along the rapid scaling of space-time the fluctuations these Quantum field Energies permeated the universe and they were inflated along with it so this when inflation hit and blew up the proton to a grain of sand or the human cell to ten thousand light years across these fluctuations were permanently froze into the structure of the universe in his Harvard astronomer aviloib per pounds in his book the first galaxies he thinks these Quantum perturbations actually led to the inhomogeneities that ultimately birthed the gravitational fluctuations around which the centers of galaxies galaxies clustered around in the early universe and he thinks these Quantum perturbations were actually what seeded the first stars and then the first galaxies this then set the Universe on its course towards our current state it ripped gravity in the atomic forces apart they were unified at a certain point before this this instant after the big bang then the atomic forces themselves went ahead and split into the strong then the weak then the electromagnetic forces once the electro weak Force split and all this all this that just happened was less than a billionth of a second after the big bang into the birth of our universe [Music] and so if we play that out a billion more times to make a full first second of the universe by then it solidified all the current abundances of particles and photons and Energies that we know now particles and their antibarticles like electrons and positrons they popped into existence at this point but instantly began annihilating each other and this left an oddly fortunate for us Surplus because it's the particles not the antiparticles that were made of the leftover quarks from these annihilations then snap together into triplets to become protons and for about the first 20 minutes of the universe still at billions of degrees mind you it was hot enough to fuse the protons themselves into doubles and triplets making helium and lithium in small amounts although most of the universe was still single proton atoms without their electrons so we call that ionized atoms of hydrogen and it's even speculated that at this point within still the billions of degrees in swarming Energies in the conditions of this early state of the universe that primordial black holes could have formed in these two could have actually been the origins of the first Galaxy cores interacting with the Frozen in Quantum fluctuations of becoming massive ultimately massive gravitational attractors that the first Stars might begin to orbit millions of years later so at just 20 minutes old the universe had swollen broken its Unity sewn Quantum fluctuations into the largest scales imaginable birth and then annihilated particles even possibly created the first singularities by about the first hour billions of degrees had cooled down to just millions in nuclear fusion had stopped freezing the the abundances of hydrogen mostly probably about 75 hydrogen with the remaining 20 or so percent being helium and then a few percent of the heavier three proton nuclei lithium but the entire universe wasn't cool yet by any means it was now just a white hot plasma of high energy radiation coupled to a dense cacophonous sea of protons and electrons in fact this universe was still at such high energies it's calculated that there were more photons released here in the next few thousand years from this furnace at the beginning of the universe then the sum of all photons from All Stars all astrophysical phenomenon in the 14 billion years since and despite the fact despite the fact that there was continually more space for this Cosmic flood of radiation to expand into and cool off into one is kind of a metaphysical question of course but um it still took hundreds of thousands of years to do so it went from Millions to tens of thousands to gradually just a few thousand degrees Kelvin and in this first hundred thousand years of the universe any point in space whether you're inside it or some metaphysical being standing outside it would have looked like one continuous unimaginably bright star millions millions of light years across matter and radiation were perpetually just ricocheting off each other and only at the end of this period of hundreds of thousands of years would they be able to cool off enough to dim the cosmic lights just a little finally at about four hundred thousand years after the big bang the environment allowed electrons to bind to protons forming the first atoms in the glow of the cosmic furnace we have existed within until this point started to quiet down a bit for the first three million years all we'd see if we were some unfortunate being left to drift in your infinite boundless field of simmering down matter and radiation all we'd see is this omnipresent wall of white light white initially though and then gradually fading it would probably seem like we're at the center of some massive Hollow star whose interior walls were glowing towards us but also receding at the speed of light once this initial grain of sand that we talked about had continued expanding to eight millimeters eight kilometers eight light years 80 million light years by about that point that wall of receding light being about 40 million light years away from us things were now Cooling in their light was becoming dimmer and redder Thanos receded over hundreds of thousands of years it would dim and grow yellow orange and as this orange Cloud finally gave way to more more of a diffuse gas getting redder and fainter with each passing Millennia it's light and eventually even its warmth would extinguish altogether and it's here at the beginning of time and in just the first few million years of existence that the Universe entered into What's called the Dark Ages nothing but Darkness nothing but diffuse clouds of hydrogen and helium cooled off until they lost their glow and warmth and were expanding diffuse matter all light from that ancient background wall traveling away in long long since dissipated no new light would form for almost a hundred million years after this just black since then that matter that emitted that warm glow has in the interviewing time mostly condensed into galaxies with the remaining matter being superheated into Intergalactic inter-cluster gas in the inner cluster medium in those galaxies are now calculated to be about 46 billion light years from us today that's a shift of a bound a little over a thousand times further away than that 40 million light-year distant wall of finally dimming light was but the universe might not be as infinite as this makes it seem the actual size of the whole universe see this is where the distinction between the observable universe and the true universe capital u universe is important because light at a certain point is being one of the fundamental speed limits of the universe constraints in the physical limitations of the universe light cannot travel faster than its own speed now with space stretching it can cover distances further than a static Universe would allow light to travel because as it travels almost like walking very fast on an airport escalator or one of those moving sidewalk fancy situations although the distance between two objects will continually expand the distance between the emitting object the object the Galaxy let's say that emitted the light and the light the the head of the light beam itself will have also expanded so it'll have expanded into a distance larger than that light would have traveled from the emitted Galaxy in just a static universe itself so it seems from the emitting Galaxy's perspective that the light is receding away at greater than any possible light speed would ever allow for and in fact one of the furthest galaxies until some of the Amazing Discoveries that we're about to mention today was at What's called the redshift of 11.1 and that meant that that Galaxy that emitting Galaxy was so far away from us even back then at the earliest within a few hundred million years of the universe it was traveling the expansion of space was causing it to travel and us to travel from it at a speed four times greater than the speed of light now of course light can't keep up with that so at some point that distant Galaxy will recede just like that wall of light into a redder Factor out of the visible spectrum into obscurity at the edge of our observable universe [Music] so that's all to try to give you an idea that our pocket of the universe is limited by the galaxies whose photons we will and at a certain point there's a boundary at which we will not ever be able to see photons a certain distance from us and they're so far that in receding so fast that their light despite traveling towards us will never cross what's Colin the event or particle Horizon of the universe so the size of the universe isn't known and in fact it's thought that according to even mainstream cosmological models the universe may not even have a physical boundary in the first place so every point in the universe whether it's inside our observable universe or outside it has its own radial lines that will never reach any sort of boundary so it's really important to understand that we will never be able to see distant galaxies Beyond a distance that cosmologists have calculated was about 46 billion light years away from us now meaning the diameter of the the sphere in which are that that defines our observable universe is about 93 billion light years across it's way more than just the 13.7 billion years that light could travel since the beginning of the universe then that's due to the expansion of space as we'll be diving into later but even then that's just a spec according to even mainstream cosmological models that that's just a speck a small fraction of the subset of the potentially larger proper universe that we live within but of course we can never observe or detect in any way whatsoever and there's even some cosmologist that would take that as far as to say that if not being billions of times larger than our observable universe it might just be infinite another really interesting fascinating possibility given well giving you information about the universe and in the parameters which cosmologists use to try to characterize the fundamental nature of space-time at the farthest and grandest scales of the universe is the curvature of space-time itself and if our universe is flat like they think then we do have a universe in which it is expanding outward and probably doesn't have a limit but if it is maybe maybe we're and this is a huge possibility detecting and are observed observations and our data of the deepest galaxies and phenomena in the universe is inaccurate or or were being misreading it then the curvature might actually be positive negative curvature would create that saddle-like appearance flat curvature would be flat positive curvature would be essentially the 3D analog the three-dimensional analog of a two or the four-dimensional analog rather of a three-dimensional globe that has curvature in which overlaps laps back onto itself and this has a really unsettling implication which if it does have a positive curvature of the universe we live in that means that it actually isn't 43 or 46 billion light years in radius but it's actually smaller than that and the furthest galaxies that we're seeing might actually be infant images of our own Galaxy in other words light has traveled along a curvature for such a long time that it Loops back onto itself like a sphere so some distant galaxies might be duplicate images of nearby galaxies just that earlier epics this is one of the many things we still haven't confirmed another thing is another aspect of the universe is its structure and its hierarchical structure too we have planets forming around stars that group into galaxies swirl around those centers and those galaxies themselves group into Galaxy neighborhoods of local clusters then larger super clusters these kit on the scales of hundred and tens to hundreds of millions of light years across and at that point these these structures are looking like you know the root systems or or even more accurately maybe brain cell structures the networks of brain cells and if you inflate that if you scale that out far enough the the groups of filaments form into walls and sheets it's thought that at this point this is what's called the end of greatness in the universe there are no scales larger than this at which there are if we think of galaxies as stars that swirl around in their own galaxies there are no other galaxies there are no swirling centers of mass around which superclusters swirl [Music] but we didn't know this until recently it wasn't until the 90s that cosmologists percent sophisticated enough technology and saddle on satellites up to probe the universe at the deepest scales the deepest depths to be able to see piece together maps of our observable universe on these grandest scales and really determined that it is a homogeneous smooth sponge foam-like structure and that's important because we don't know so much about the universe still we have so many things that we are literally in the dark about we have the Dark Ages we don't know when stars first formed or how all that expected hydrogen really collapsed we don't know how galaxies formed we have black holes we don't know whether or not they formed like I mentioned in the first seconds of the universe and these were the seeds around which matter collapsed into and coalesced and became the gravitational Wells sitting at the cores of the first and still current galaxies we don't know what dark matter is another huge what we expect what we think is halo-like structures within which most galaxies appear to sit almost like they're corralled in these spheres of undetectable in inert non-interactive matter we don't know finally what dark energy is we have no idea what this is it seems to actually prove a an initial Theory or an actually initial set of parameters really that Einstein in the early 1900s when he came up with special and then 10 years later general relativity and started applying them to astrophysics and astronomy cosmology even though within we'll talk about that too it was only thought that the Universe was the Milky Way only a few hundred thousand light years across maybe a million at most but um dark energy was a hypothesis Einstein inserted into his equations called Lambda he used the variable the Greek letter Lambda to offset the gravity the gravity of matter that bends space-time and he said in order for the universe in his mind to be static infinitely enduring thing to prevent the stars and the matter within it from collapsing over time he inserted a almost anti-gravity pressure and outward Force propelling encounter acting gravity he then dropped it when he realized Hubble Edwin Hubble a few years later in the Matra and a few other people discovered that the Universe was actually expanding and saying that okay so we don't need this Force and this expansion doesn't really tie into Dark Energy so we dropped it and then 100 years later or so about maybe 70. this guy along with a team of other people helped discover dark energy they they were able to measure supernovae at massive distances Away really really distant very red and they were able to see those features of these distant supernovae pointed to an expansion that was Far faster than what the momentum from the early inflation of the universe would have led to this Forest cosmologists to posit a an energy almost exactly equivalent to Einstein's Lambda and we don't know what it is though it's a vacuum energy that expands the metric of space itself much like the inflaton particle that filipenko on Lex Friedman's podcast actually talked about maybe you've dissipated into other particles and then maybe over spans around the time that they think the universe has lasted for 14 billion years maybe that particle came back into play somehow so there's so many things that we are very much ignorant about and there's also though a lot of breakthroughs that happened in the 90s in around the same time that these redshift surveys started giving us a an eye on the true largest structures of the universe the Kobe satellite for instance a led by scientist John Mather the Kobe satellite in the 90s measured the cosmic background light that we just mentioned that was emitted from that early Haze of white hot hydrogen plasma over the 14 you know billion years that's happened that receding sphere of light has shifted far beyond the red and then even far beyond the infrared way into longer microwave wavelengths such good data from this Kobe microwave detecting satellite actually helped resolve those large oscillations like this that we see it's been refined in really measured in way greater detail since then but in the 90s this was a breakthrough for cosmology they helped us see that these oscillations might have been these fluctuations that were seeded by the quantum field fluctuations Frozen into a structure on the largest of scales and around which Dark Matter might have actually coalesced and the Kobe satellite even detected the first that hydrogen that had emitted its light long sense and over the next millions of years cooled down from thousands to hundreds to tens of degrees above absolute zero so this ice cold field of hydrogen mostly drifted of course for millions of years in the dark dead universe until the first Stars would ignite and light up the universe also around the same time in the 90s scientists discovered the first exoplanets the first planets orbiting Stars far outside our own solar system these were the first planets that we ever discovered other than our own and once that first discovery was made the motivation and Technology was fixed on discovering more and hundreds and then eventually thousands of more were discovered in the race Define alien life on planets began it's actually now known that roughly one in five Sun Stars similar to the Sun have earth-sized planets around them and even though we haven't really detected a lot lots of them whose atmospheres we've been able to measure show that show that they aren't very hospitable to life but the math that might stop you in your tracks is that the Galaxy we live in has 200 billion stars in it and our sun is very common it's not an outlier by any means so even if we say only half of those Stars 100 billion are similar to our stun sun and then one in five of those have Earth-like planets around them that means that about five to six billion planets like Earth exists just in our our galaxy alone the odds that those have alien life on it are pretty high in all this the dark energy going back and measuring the cosmic microwave background seeing the first Hydrogen fields that might have turned into the first Stars the first exoplanets in the tantalizing evidence of the sheer volume of planets that are out there waiting to be discovered all this was in just a few years of each other in the 90s and it was in the midst of these revolutions Illuminating our these huge domains of ignorance about the cosmos that we live in that the James Webb Space Telescope was born [Music] so much of telescopes involve the simple Gathering of light and deducing from that information the nature of the universe and of course we apply physical experiments on done here on Earth and now in satellites in space and the laws of nature that we've determined from that to this light that we're detecting from billions of light years away but it really is light at the center of everything nowadays we know that photons the basic structure I'm sorry the atoms basic structure our nuclei their nuclei with protons and neutrons call them nucleons together and they're orbited by these really tiny particles with high energies called electrons and these electrons can orbit at different ranges or different configurations that link them to different energy levels but around any given in any given element it's defined by how many protons it has and usually with protons you have roughly similar number of neutrons in the atomic nucleus and that somehow because these protons and electrons are fundamentally charged particles with the electromagnetic and the electromagnetic sense they they create a feedback loop of sorts with each other such that the electrons energy in order to change up or down through absorbing different wavelengths well can only absorb specific very specific frequencies of light and that's where these fraunhofer lines came in from the Sun and you know the Bunsen burner and kirkhov noticed in their lab these lines are able to they come from the fact that as you have a different nucleic configuration different configuration from different amounts of protons given different nucleus you know oxygen has eight hydrogen has one gold has 79 or something like that so there's 79 protons in the nucleus and roughly another 79 neutrons in there too and of course that makes it bigger creates a much stronger positive charge that the electrons have to interact with in a loop now and so therefore for the electrons of a gold atom to absorb light they would have to absorb a much different frequency to be able to shift them into higher and higher orbits of around the much more positive gold nucleus with all its protons then the tiny little single proton hydrogen nucleus um the hydrogen nucleus is well it's important for cosmology and astronomy but um I don't think I need to focus on that one in particular it's just very it's very interesting that these each atom has its own very specific characteristic set of spectral lines and because most of the early Universe was hydrogen because other than some a little bit of helium and lithium no other heavier elements had had the time to form because again there weren't Stars yet for millions of years so because hydrogen dominates the early universe scientists specifically want to know what hydrogen spectral series of lines looks like and they want to know that because they can look for that in the light from the distant by peaking through the nearby stars and galaxies and peeking into distant voids hopefully seeing some of the earliest radiation that's able to make it through that Cosmic foam-like structure and hit our lenses they want to analyze properties of hydrogen and turns out that there's very specific properties of hydrogen lines that are able to tell us how far away for how long the light's been traveling over how much space the light has traveled and other features like um the abundances of hydrogen in a given Galaxy that's being observed and so so the the structure of the atom and how it interacts with the light is extremely important in cosmology in fact it's fundamental it's it's foundational and it is what every theory of cosmology in the universe we live in is built upon [Music] the easiest way I found to describe atoms and how they interact with light and Emit and absorb light and it's momentum that it represents its energy is that you have a spectrum so let's look at this we have at the lowest end [Music] let's think of let's think of how light impacts matter if we shine light on it we have different types of light right at the lowest end we have radio in microwaves and as we get shorter wavelengths higher frequencies more energy we go into the infrared and then the visible red starting with red being the longest visible and blue being the shortest then as we get even higher frequencies we go into the UV and at that point UV bleeds into the x-rays and gamma rays those are the highest energy things that's why when you get an x-ray at the doctor's office they put lead vests on on all your other areas not an important areas to look at because it goes penetrates right through you it ionizes the atoms in your body and small doses like machines use as far as we know now for with 100 Years of observation it doesn't really affect you too much but um and I guess doctors only wear all them and leave the room because repeated exposure if you're around it all day will affect you too much but it's it's the the easiest way I found to describe a light and to understand it conceptualize it's the way it's broken up is actually to break it into regions of energy so let's say the microwave and in radio being the lowest energy and and how that relates to the way atoms move and interact atoms being intrinsically charged sets of particles it's protons with positive electron with a negative sometimes or many times it's multiple protons in the nucleus multiple electrons um surrounding it at different energy levels and we have groups of atoms of course atoms rarely exist just in isolation they exist in a material oftentimes and so the displacement of atoms and crystals for instance it can jiggle around and anytime a light anytime an atom is above zero degrees absolute zero it has some sort of intrinsic vibration some sort of intrinsic energy to it and that always emits some photons so it's ever just through the ambient temperature especially at room temperature but you could even go to the coldest place on Earth all atoms will have some sort of Ambient Energy and vibration movement to them that will cause them to spontaneously emit protons or photons and um the hotter you get so if you go from the coldest point in space absolute zero into our the uppermost layer of our atmosphere being really cold it'll start emitting more and more high energy photons low energy radio and microwave photons for cold gas in space and then as you go through our atmosphere and get hotter towards you uh as you approach the ground level room temperatures you get more infrared because that's a slightly higher energy that the photons infrared photons that the atoms on Earth are emitting because they're starting to really get a lot more ambient temperature here and uh of course as you go to hundreds of degrees you get hotter and hotter you go towards uh I'm trying to think of something in between us and the Sun but anyways as you approach room temperature and get hotter like the oven for instance like like an oven at 400 degrees that'll almost get to the point where light visible light being much more energetic than infrared and way more energetic than microwave and radio waves is emitted and so the best way I found to describe it if you have atoms in a crystal in the Crystal and they're jiggling and they're they're kind of going back and forth in more of these large-scale oscillations within a structure that's going to create a lower frequency than the higher frequency vibrations of the individual atoms those and in molecules in particular and those can go through translations where you have I'll show some here the infrared translations those will emit higher infrared frequencies then you have electron transitions um that are not the vibrations of the whole atoms but the way more intense higher frequency high energy vibrations of the electrons themselves orbiting or spinning or moving with some sort of angular momentum around the atom those emit in their uh leaps their Quantum leaps through different orbital energy gaps around the atom those emit even higher radiations being UV are being Optical up to UV and then you have ionization which is free basically free moving electrons that have so much energy that they're broken free they just can't be bound around the proton nucleus they have kinetic energies that are infinite because they are no longer locally bound to an atom and those will emit x-rays up to gamma rays I guess sometimes I hope that made some sense to you hopefully I put enough pictures to make you to register it but that's how I understand it at least it's important because of how the universe shows us light for us to be able to understand what's going on whether it's whether it's looking at the atmospheres of exoplanets and how they filter their own Sun's light on the way towards us if the orientation of the solar that exoplanet distance star system is oriented so that the planets are orbiting in front of their sun with respect to us um and then the makeups of gas nebulae other stars we can see the Spectra of other stars and in fact anything that emits light in the universe we can break into a spectrum see tons of characteristics and details about and this relates to the the visible appearance for us of an object you know for example what's interesting is the so the molecular transition of what's called retinol which is the molecule responsible for vision in our eyes is is what makes our vision work and this is the molecule right here so it undergoes a series of Transitions and of course you could see with all those atoms it's got 20 carbon 28 hydrogen and one oxygen one little oxygen atom the combination of of different frequencies between so you know the Spectra the absorption and emission Spectra of elements and individual atoms combined into molecules is completely dependent on what the shape of the molecule is what the atom atoms are how they're configured how many there are of course how many electrons in each atom atomic orbit there are and in certain you know ring-shaped molecules they even share electrons which is a really cool phenomena so that different structure even itself can change the frequency of different types of frequencies that of light that they absorb so each molecule even beyond the elements beyond the atoms each molecule combined of different atoms has its own characteristic spectral absorption and emission lines are the molecular transition of retinol is when sunlight or any light that falls within our visible range that we can see hits our eyes it stimulates these molecules that send neural signals to our brain to register it as as some sort of stimuli from outside of course unless we're in a simulation and it's all in our brains like the Matrix but yeah it's just interesting that that's you know the mechanism for how we how we see no black object just in general terms how objects appear to us a black object like we talked about as such as coal has no reflectivity purely bright black object it will absorb all colors a white object reflects all colors like snow a silvery object such as a mirror reflects colors specularly an opaque colored object so something I mean anything that has a specific color to it basically absorbs all the colors but the color you see now Rose absorbs every other color but it's red wavelengths if it's a red rose for instance transparent object emits or or sorry allows the transmission through itself of all colors like glass and then stained glass for instance a semi-transparent object or colored liquid will emit only will absorb all the colors and only allow the color that we see it as to pass so a blue liquid would only allow blue light coming to it to pass and even the sky the reason the sky is blue it has a molecular as an explanation based in how light interacts with molecules in our atmosphere it's because the sunlight has plenty of red and blue it mostly peaks in green but it has plenty of all colors the reason the sky is not purple or orange or green and it's blue it's actually because blue being the highest energy or the lowest uh smallest wavelength of the visible spectrum that we can detect is scattered it just happens to be scattered by the particular molecules that we have in our atmosphere it's scattered really well and apparently as there's a law I forget I guess I didn't write it here but there's a wall a law that says that light of wavelengths of shorter frequencies are scattered with a scattered more on the order of magnitude of like four times uh so like 4 000 or 40 000 times as much sorry won't be ten ten ten thousand that was way off there it's it's ten times but it scatters 10 times more than red line so as we look at the sun even though the sun has all these colors we perceive all the colors mostly are coming through although some of the blue light is getting stripped out because it's getting scattered way more than the red and we're seeing the white sunlight as it hits us when it's overhead but all the blue ladies being scattered all over the atmosphere at 10 times the rate and red is and that's why so all the Blue Line we're seeing from the sky is actually sunlight that's been deflected and Scattered way off in the distance and bounced back towards Earth and because blue does that more than red that's why the whole sky looks like it's blue because all those molecules oxygen and nitrogen prefer just based on their shapes and how they interact with light they prefer they tend to uh to not anthropomorphize it too much they just tend to scatter blue light way more than red and then red sunsets occur I believe because it goes through so much more atmosphere that at uh oh do I remember why a red sunsets occur I think it has something to do with the angle of the sun being really low to the horizon so it has to go through way more atmosphere [Music] I believe there's maybe another effect at a really low angle that comes into play that allows more scattering of longer wavelengths like red but the quantum mechanics the nature of light the black bodies and the UV catastrophe that's all important because stars are modeled as black bodies and they make apparently they make really really good um very accurate very close approximations to black bodies when physics when all scientists make a decision about the assumptions for any particular model what they do is they usually make a reasonable trade-off between the acceptable model errors and the difficulty of calculation of the mathematical curve they're trying to fit to the phenomenon so if there's a curve that just roughly corresponds to it and then there's a curve that's a very close fit but you know infinitely more complex to calculate they're probably going to use the one that just is more of a rough fit because it's close enough it's good enough and will save them a lot of work maybe that's why our AI systems in the future will help modeling the real world way better but they've used for centuries for at least a century I guess they've used a black body curve to simulate approximate the sun's spectral emissions and there's what's called an HR diagram that is roughly a a relationship a very a very well-defined relationship between color of a star whether it's blue orange or white or yellow and the temperature of a star and that comes from the black body relationship of color of of temperature to the peak wavelength of that black Body Curve or now known as the plug curve and there's a another law that goes along with plancks called the ovine's displacement law that tells you exactly at what wavelength that black body will Peak for any given temperature regardless and this is cool because it's regardless of what that material is made up of so it could be if it has enough atoms essentially it could be all perfectly one element and they won't emit that one absorption line they'll emit a ton of a continuous Spectrum just because there's so many geometries going on and there's so many vibrations and rotations of molecules emitting different wavelengths and energies so even scientists are even able to estimate how hot lava is based on its color which is I thought pretty cool and there's tons of other examples of how useful black bodies really are I think I put this in here because the main point I wanted to make was that while I was studying why the web telescope was built specifically to be infrared I could understand that you know maybe well one of the big explanations was that when things were redshifted when things were far enough away of course the expansion of space causes the what was initially emitted as UV or visible light is now stretched into the infrared and so they're actually invisible galaxies it looks black to if Hubble hadn't been equipped with its infrared sensors it wouldn't be able to detect half the galaxies in its Deep Field but that doesn't explain why the light was mostly UV and white to begin with and that's why galaxies were mostly [Music] um emitting their most of their lights why they peak in the optical in UV light range it's why a lot of galaxies unless they're very very high energy collected cores quasars or supernovae don't emit a ton of X-ray radiations because of that ultraviolet catastrophe that drop off in the peak as it gets hotter and hotter um as the temperatures get hotter so turns out that most matter most stars Stellar matter of course makes up galaxies so most galaxies composed of stars in the universe emit almost all of their radiation which has a ton of the spectral line information in it that tells us the composition and the you know densities of the stars and the temperatures they will they emit at temperatures that peak in the visible and UV wavelengths so and I was always wondering why like why aren't we using optical telescopes to look for ancient really distant x-rays that's been shifted into the optical or why aren't you know infrared why aren't we using radio telescopes to look for stuff that's been shifted into the radio and it turns out you know we are to some extent doing that but the bulk of the galaxies that we're going to see in the first Stars we might see at the beginning of time after then the first 80 50 million years even possibly if we're gonna see that we're gonna need infrared light because then light emitted from them peaked indivisible exactly in accordance with the black body Planck curve so that's been shifted since then [Music] so what is cosmology it's the study of the origin in the evolution of the entire universe the biggest picture we have of our existence I think that's why it's so fascinating it's um this is actual an actual cosmology book here an introduction to cosmology there's a scary amount of math in here I actually wasn't expecting that cosmology tackles all the big questions what's space made of how long has the universe existed and how long will it continue to exist how was the early Universe one of the big ones Webb is asking different from the universe of today Aristotle's universe as we kind of alluded to was different way different than ours but it has some features earlier ideas were still transmitted the ones that stood the test of observation have informed our current understanding of the universe [Music] Aristotle's Universe had an edge of space and outermost fear upon which were fastened the Stars but the cosmos that he understood I had no beginning so it had infinite existence in time in on the heavens Aristotle wrote that the he wrote that the primary body of all the primary body of all is eternal suffering now their growth nor diminution but it's ageless unalterable and impassive and then the judeo-christian world view coming out of Eastern Mediterranean did away with the eternity but it maintained the idea of Cosmos of a cosmos with that was finite and without change so it didn't change but it was it did have a definite beginning and a definite end that would be the uh what's that called eschatology according to this in many other ancient Traditions the universe was created from nothing and has remained at the same ever since but then Copernicus in 1543 he demoted the Earth to a mere planet around the Sun like we talked about and that changed the way we looked at things this wasn't uh changing the Earth's Italian belief though that the Universe was built spatially finite and static in time so what Copernicus thought of still was like yes um things everything didn't revolve around the Earth but in fact the Earth spun and we revolved around the Sun but it was still a specially finite Universe there was an edge to it and over time it didn't evolve it was eternal it stayed the same and then maybe half a century after Copernicus Thomas Diggs became the first copernican to pry the Stars off their crystalline sphere that in that finitely static edge of space and with this effectively did was spread them throughout space it was the first time scientists people had consciously really thought that possibly the Stars might be at different distances and they might exist the way in a three-dimensional not uh Paradigm rather than just a two-dimensional you know stuck to the two-dimensional surface of this distant sphere but even then the universe was still viewed as unchanging with time Newton even argued the same view a century later he discovered the ideas to uh you know the the actual math behind the planets orbited but even then he couldn't bring himself to imaginary universe that had motion Beyond just the planets around the Sun and so this universe he assumed remained the same from one Eon to the next there's one Paradigm in in this book here I mean it's not from this book it's just a age-old Paradigm called or Paradox called obers Paradox it was a paradox that was meant to refute the argument that the Universe was infinite basically really just a way of saying that if it was infinite in space and time then why isn't the night sky perfectly bright as bright as the surface of a sun it says that if there's been infinite time for an infinite field of stars to exist then why hasn't the light from All Those Distant Stars come in our field of view basically so the guy in 1576 Thomas Diggs he mentioned how strange it was that the night sky is dark with only a fin few pinpoints of light to Mark the locations of the Stars and Ober came along a couple hundred years later and he uh he tried to formalize that and saying well we can rule out that the universe is infinitely large full of um you know in in uniform and matter and that it's infinitely old if it was all of those there would be the light from even the most distant Stars would have had time because you know at that time they um they were well by ober's time in the 1800s they knew that light had a finite speed he theorized that the uh infinite time of the universe would allowed it would have allowed infinite time for the light to travel and therefore it would have reached our eyes and if the universe wasn't just a few you know a few Stars a few thousand stars and then it just ends into Blackness if there was a continuing field of stars all those Stars would have contributed to filling up the entire night sky with light all the black voids anywhere would have at some point at some distant enough Point been occupied by a star on its apparent position relative to us our view from Earth and so we could tell from that Paradox at least logically the universe isn't old or at least there isn't a uniform field of stars Beyond a certain point they must end at a certain point which might mean there's a finite space to the universe too and so I thought that was a pretty cool idea it's one of the first instances where we start to view the universe is having potentially other systems and the Stars being other star systems like our own with planets you can add different varying distances with glowing Sons um that themselves might possibly move not be like stuck statically to this crystalline unchanging sphere [Music] and cosmology progressed starting with around Galileo and then about 75 years after Galileo Newton took Galileo's it wasn't Galileo's invention but he was one of the first to hear of a telescope you know a lens being ground so that you could look uh magnify distant objects and then Newton 60 to 70 years later perfected really designs that were used for the next couple hundred years after that he came with the first practical reflecting telescope which meant it didn't just come on come in straight to uh let's see if I got a picture of it here yeah it didn't come straight to your eye like galileos so you didn't just point it and look right behind where you were pointing it was actually came in through the lens and got reflected off this little mirror here in which focused it perfectly on your eye on the side of it so these eventually got crafted more and more to allow sharper and sharper images the lenses were Ground smoother their ground with more magnification then we had some modifications like this where you could actually you had the uh so you had light coming in here bouncing off their both not quite focusing on here but this was set up so that the focus would ultimately come right to your eye the light of the Gregorian telescope developed not too much longer after um Newton so these are all in the early you know 17 late 1600s even these designs have been around for 300 years or yeah even more than that um it's amazing that they're still mostly just kind of elaborated upon the design hasn't really changed that much and this one just has a the light comes in from the right if I can make it larger and bounces back off onto the mirror but then reflects right back to the Observer so it's not a direct it's built to look like Galileo's refracting telescope but it's actually a reflecting one what you're seeing isn't the light coming right in melting off two different lenses before it hits your eye and then this one is the same design except the lenses the mirror here is concave or con convex rather than concave the Casa Grande reflector actually invented in 1672 so even before Newton this is actually the uh so the optical path by folding back on itself allows it to have the same magnification as a hyper long reflector telescope wood so other than like some materials and tweaks on you know the types of metal they use for reflecting in glass Material Science it really didn't change that much for 350 years which is a phenomenal now here we could see the so I hope you guys could see that right there we see that the uh the angular resolution is strictly dependent it's one of the great you know features of math that we're able to see like a very precise relationship between the lens diameter the diameter of the primary lens that's collecting the light and how sharp the image looks and what we see here is that you know for Hubble it has to do with the wavelength too so it's a relationship between the angular resolution is the wavelength divided by the diameter of the lens which means for a smaller wavelength like visible light smaller than longer wavelength infrared light that web sees what you want is to have a smaller angular resolution small as possible so for any given diameter what that means is that for any larger wavelength you need a larger diameter mirror or else as you get a larger and larger wavelength going out of you know relative to visible light if you go to infrared light the resolution will decrease because the numerator is getting larger there so as you have infrared light you need a much larger mirror then for instance Hubble which is focused on primarily observing shorter wavelengths from the visible light so it needs a smaller mirror but it still needs a it does need those mirrors to be polished to within a fraction of Lambda the wavelength which is insane now how how smooth that has to be so for the last Century last 300 centuries we've been using reflectors of some sorts but um there's been a new type that the web actually is using and it's incredible because the Optics are such that it's able to have the the light fold back on itself so many times that it for web in particular creates the effect of having the same effect as having the Magna magnification of a four I believe a something like a 400 foot um long focal lens all within a design of about 20 feet because it's as the main primary mirror and then it has the secondary mirror suspended about 20 feet away which is giving it uh just amazing amazing resolution so a quick run through the astronomy and cosmology that is leading up to you know everything you're going to see in the headlines for web and the telescope defining uh galaxies as far back at end time as as it'll be going like I said in the intro every almost every month you should be expecting Webb to be making brand new discoveries and that's because it's seeing in the eye infrared it's and it has its massive mirror extremely polished it has high-tech state-of-the-art sensors and we're going to be seeing things that are are changing the way or or it really is they were trying to they made a point in multiple articles I read saying that and they're not trying to reinforce the status quo of cosmology they want to just get the best observations they can and see if the current cosmological model called the Lambda cold dark matter model Big Bang model to complete the whole phrase is um they want to see whether it stands or Falls with the amazingly high resolution observations that web will be performing and so I think it's important to understand the background behind our current understanding our current theories of of how the universe came to be I mean why we think it came from The Big Bang why don't we think it's just a steady state and it's always been that way um how we think galaxies evolve Stars how exoplanets are made how many other Earth-like planets there might be out there and of course how many how many alien species on different planets would that possibly mean there might be how much time how many other galaxies are similar to ours it turns out we're we're actually in a pretty unique Galaxy most of the galaxies in the universe lie within these massive superclusters and they have these these elliptical features that mean that star formation is fairly non-existent in them it's already they've already developed most of their Stars already and turns out the spiral structure we believe that we exist within that our Milky Way is is a transitory phenomenon in in galaxies that are able to still have starbirth uh ongoing the waves of the arms the rather the the arms of the spirals create waves and shock waves of uh energy that hit these fields of stars that create new stars to be birthed out of nebulae of course all happening over hundreds of millions of years but um it turns out that we actually lie on a Galaxy that's pretty far away from any core of these superclusters as we'll see it lies kind of on the edge and we have these huge voyance billions of light years or hundreds of millions of light years across within this foam-like structure and we're actually more on the outskirts of that than we are close to the center of any one of these huge these dominant super clustered nodes that we see and so we're outside from The Fray and then not only that our galaxy in particular is very habitable to life so it's not likely we're going to see aliens outside of our galaxy but within the billions of stars within our galaxy it's very interesting to know that we have a very hospitable Galaxy relative to many in the universe yeah it's just amazing all the all the discoveries we've been able to perform over the last few hundred years of scientific investigation I mean we've been able to detect helium and hydrogen in the Sun the masses of the Stars based on binary orbits and how they perturb each other's gravity how gravitational perturbations alertiness of the existence of a planet Beyond Uranus which ended up being Neptune then Herschel actually discovered the same guy who discovered infrared radiation and even in detecting the parallaxes every six months we orbit the Sun and you can see my Scale of the Universe video for a little demonstration on Parallax how amazing of a tool that really is to be able to see how some trigonometry can give you the distances and we have enough High Precision telescopes now Hubble was actually key in doing some Parallax research to let us know the true uh unequivocal distance to some of the most nearby Stars based on how it orbits around the Earth or rather how it orbits the earth along with the Earth and in its orbit around the Sun so every six months Hubble is able to look at the same star and see a slight shift in the background stars of this relative to this nearby star and so it's been able to vastly expand our knowledge of just how distant spaces between the stars in our local neighborhood [Music] but really for 300 years Einsteins or Newton's concept of gravity his theory of gravity dominated science and our understanding of astronomy it was extremely effective and it explained everything in the solar system except Mercury Mercury had an anomalous orbit and with that ended up being was uh an effect of relativity because Mercury is so close to the Sun that it's actually within the realm of observational relativistic effects from the Sun's gravity being so massive that it bends time and bends space around it in such a way that Newton's gravitational Theory had not accounted for so there's a small variation a kind of a wobble in the procession of a yeah I guess A procession of the elliptical orbit of mercury but that fit the model perfectly but it was still amazing that took 300 years to do and what's maybe even more amazing is how within that 300 years and even after it even after Einstein comes we have these we have these conceptions of the grandest scales of the universe and one was this steady state Theory many including Einstein believe it or not they held on to a steady state theory for a long time even after the expansion of the universe was discovered and the expansion of the velocity of galaxies traveling away from us was found out we believe that the Universe didn't come from anything you know it was just God religious text religious context that created the universe and so it was unchanging it was static the galaxies were wherever they were the stars remained where they were um only they you know the the solar system had dynamism to it so Einstein initially even believed that this cosmology this this steady state infinite you know infinitude of cosmology made the most sense but it was his own two revolutionary ideas the one of light as a fundamentally indivisible particle a photon and of matter as bending space-time of course causing light to bend with it that would reframe everything we know so Einstein's new physics coming out of deep thought experiments he as he pondered the consequences of traveling at the speed of light around 19 early 1900s he established this um this helped them establish a special relativity and then in 1915 10 years later roughly his generalization of the theory in general relativity in these revolutionized the whole paradigm of cosmology the nature of space and time now became intertwined by the way that matter actually distorts them he was inspired by the fact that all objects followed the same trajectories he had thought this I wondered why they all followed the same trajectories under the influence of gravity and realize that this would be a natural result if space-time is curved under the influence of matter so he wrote equations called the Einstein field equations describing how the distribution of matter on one side of his equation determines the curvature of space-time on the other side he then applied his equation to describe the global dynamics of the universe now when he did just like we talked about earlier scientists like to use the simplest mathematical model possible and you know there's billions trillions of objects in the universe so Einstein's being in the early 20th century without so much as a you know a calculator to help them get by into any of this math he got around this obstacle by considering the simplest possible model of the universe one that was homogeneous or homogeneous and isotropic that means just like a foam structure there's no there's no pull one way or another it's just one uniform that everything is a sphere it's not pointing in any particular direction like iron filaments under a magnetic field and it's not lumpy at the greatest orders of scale which is turns out like we talked about before that's how it actually is if it was skewed in in homogeneous at certain points if there was a you know a vast wall on one side of the universe and then we look over on the other side of the sky and that nothing gravitationally comparable existed then that would be a huge well it would be a huge uh letdown for any physicists that uh or cosmologists that really were invested in this current theory but so far that hasn't happened so far they haven't found any inclination yet other than maybe the potential ramifications of what Dark Energy might be that disprove this but nonetheless this for Einstein in the early days of trying to apply relativity general relativity to the cosmos this worked out just fine because um the uniform conditions everywhere of homogeneity and the same conditions in all directions from any vantage point of isotropy held true under observation and these simplifying assumptions are called something their extension of copernicus's principle that the universe is the physics and the underlying physical laws of the universe is the same at any point in the universe and this is called the cosmological principle saying that physics and gravity and particles they don't operate they don't have more mass in one area than the other gravity isn't stronger in any particular area for the same amount of given Mass you know one star of equal Mass 50 trillion light years away from here is not any crap more gravitationally pulling on anything then it is in this corner of the universe but his notion his his perception his Paradigm of the universe Einsteins was wrong because at the time it would be 10 more years actually until Hubble would come along and change this in the 1920s and before the stars that we see in the Milky Way and we got to remember the Milky Way is so vast that we can't even see stars much Beyond you know a couple light years away with our naked eye I guess that's that's true it's that's not true rather we can see a few thousand light years away I think but it's 100 150 000 light years across so even with telescopes were only seeing the nearest quadrant of stars in our galaxy and now they were seeing these nebulous swirly uh Whirlpool looking things but they thought at the time they didn't realize they were galaxies they thought they were maybe just Cloud structures uh in interstellar space Among the Stars so for all of eternity even after we had a couple hundred years in the 1800s and early 1900s of observing the cosmos and the Stars around us all the universe appeared to be was what we now know is the Milky Way but it was just for anybody back then the Einstein included all astronomers the entire universe the entirety of existence was only what we could see which seemed to be Stars it didn't seem like there were any other Islands or groups of stars anywhere else and so that's all Einstein had to go off of and because the universe didn't appear to be collapsing or expanding but this would be a one of those instances again just like the sun and moon appear to revolve around us where our senses get in the way of finding the truth for a static Universe Einstein tried to attempt to recreate this mathematically he noticed of course with all the matter and the stars that over time for uh inexperiod extended period of time there would have been a gradual collapsation of stars on themselves so he he figured there had to be some sort of repulsive Force like I mentioned that he called his cosmological constant that he used the letter Lambda he said that conceptually could be considered as anti-gravity really a a gravity that really you know repels rather than attracts so what he considered was that empty space itself had this was permeated by this negative gravity that would exactly counter matter and we'll see that this was actually really Prussian he really Came Upon something in this thought experiment in researching physics he Einstein truly deserves his reputation for being you know the archetypal genius figure he he was a just a remarkable remarkable thinker and this idea it turns out this idea will come back a hundred years later so as I mentioned earlier in the intro [Music] so the static Universe of Einstein's where you had perfect you know we didn't even know at the time we were part of a galaxy rotating around itself we thought it was just a field of stars static imposition and Einstein had to have this field penetrated the interstellar space in this field permeated by this negative repulsive gravitational force however less than a decade after Einstein had kind of theorized this and came out with his general relativity field equations that seem to perfectly explain all the light phenomenon that we're seeing Edwin Hubble then made a discovery that would prove the universe is far larger than just the Milky Way around 1900 probably 20 years earlier serfield variable Stars have been meticulously studied by a woman named a female astronomer named Henrietta leban of Harvard and she'd found a firm relationship between the actual brightness of how fast their actual brightness and how fast they pulsed because they were a periodic pulsing star they consistently pulsed every uh consistent amount of days over you know anywhere from a couple days to a couple weeks and or maybe a couple hours but they were exceptionally Bright Stars and what she found for instance that was that for any given period their magnitude that you could observe was always very consistent so even on different parts of the sky different Stars if they had roughly the same period they would have roughly the same magnitude and she studied thousands of these so she developed a scheme in a map of actually being able to use these as standard candles she compared their apparent luminosity to their intrinsic Luminosity to give their distance to Earth and that's for another video to go into more but it's really interesting how she deduced that and figured it out Hubble's first major Discovery decades later in the 20s was to identify cepheid variables and some of these larger spiral nebulae what you know was considered just nearby within the same you know Among the Stars that we are observing and most famously famously he looked at one in Andromeda and when he compared their Luminosity to the known standards he found that they were way too distant to be in the Milky Way and around the same time in the 20s it had begun to actually be seriously theorized and famously even debated and this famous debate here um whether some spiral clouds of these might actually be distant star clusters until 1924 the universe of course had been the entire or the Milky Way had been the entire universe but that changed with Hubble's findings the brightness and period of the selfie of saffigan observed and Andromeda meant that it was not just thousands or even tens of thousands even hundreds of thousands it was millions of light years away and that just blew the lid off the current Paradigm of cosmology even Einstein's theory you know he hadn't expected the universe to be that fast I remember we uh you know we know now it's billions almost 100 billion light years across that's almost ten thousand times larger than what Hubble Is Blown Away by cepheid variable was just because it was able to have the same period as a nearby variable with a similar period we saw how faint it was which meant it was a we could tell how distant it must be to be that faint and it wasn't just a one-off that was just the most prominent example he studied you know dozens and dozens of these to really hammer it down and make sure he had the numbers right so now here the universe blown up and said oh these nebulae these spiral nebulae are actually other Islands other swirling fields of stars and they're Way Beyond the Milky Way we must be in our own swirling field of stars and these other ones are the only hints at the more distant ones and so Einstein was pretty quick to grasp that if these field equations he had were true then the static Universe even one balanced with a cosmological constant couldn't possibly remain stable because local and homogeneities would ultimately lead to either a runaway expansion or even a contraction of the universe but in 1922 a Russian named Alexander Friedman derived what's famously known as the Friedman equations from the Einstein field equations just a specific set of parameters with Solutions showing that the universe based on observations and applying those two Einstein's equations might actually be expanding but the stars in nebulae in the universe weren't moving as fast either towards us or away from us as expansion would have made them but two years later Hubble would make his great redshift discoveries that would show just that Doppler the guy who came up with the concept of Doppler shifts his name was actually Christian Doppler Austrian physicist he described the phenomenon way back almost 80 years before in 1842. and he actually correctly predicted that this phenomena should apply to all waves because uh you know it has something to do with of course sound waves that's the most intelligible example to us but it applies to light waves too and um and he actually even predicted that the color shift would vary but because of stars that were you know moving far away they would shift to the red to a lower energy wavelength or if they were traveling towards us they would get compressed and shift blue back in the 1800s which was amazing because that was actually pretty right galaxies we don't see a lot of blue shifting galaxies because they don't only a couple are traveling towards us like Andromeda and triangulum but tons of galaxies from the expansion of the universe are traveling very fast way faster than the speed of light away from us making them redshifted but his idea was actually shot down because uh um actually because of black body radiation was taken root and and there was a understanding that temperature of course is correlated with color which is true but the Doppler effect was not taken into account so this um there was actually a long history of of looking at stars it was only a couple maybe a decade later a couple decades later that the astronomers first took doppler's ideas about shifts and waves and applied them to the optical fraunhofer lines and other absorption lines and stars and recognize that hey they must be they must be shifting you know if they based on their movement these lines should be you know the wavelength for the absorption line of hydrogen should be at 121 nanometers but instead it looks like it's at you know 200 nanometers what's going on with that and they kind of deduced that oh okay and maybe it is because they are traveling away and so it's stretching the light out a little bit and about 10 years before Hubble had made his famous uh cepheid Discovery and would go on to make some redshift measurements maybe closer to 20. pesto sliver discovered that a lot of the Spiral nebulae he performed some Spectra on them and he discovered that a lot of the Spiral nebulae had considerable redshifts he went on to record about 20 different galaxies that had mostly all red chips except for the few that were heading towards us he was able to calculate their velocities relative to Earth but unfortunately he didn't grasp the cosmological implications of this especially because at the time it was still you know controversial whether or not he was doing this in the 19 teens before general relativity was even out he was wondering maybe probably thinking about them as nebulae amongst the stars and wondering why they were traveling so fast away but in 1927 just a year or so after a few years after Hubble had discovered Andromeda was 2 million light years away blowing up the universe but still the galaxies seemed static at Belgian physicist a humble quaint Belgian physicist who was very interestingly also a Roman Catholic priest [Music] named George lamatre he came into the picture here and he'd preceded Hubble's next Discovery by a couple years but he wrote in some obscure journals and of course non-english language that didn't get acknowledged until afterwards but he proved independently of Friedman even the even more Fringe idea that the Universe wasn't only millions of light years across now but that it was also expanding using the equations he directly derives from general relativity on his own he'd found a precise relation between these vastly different distant galaxies how fast they were receding and then two years later the Hubble built upon sliver's work and he provided these detailed observations to prove these ideas he noticed that these newly discovered galaxies were in fact redshifted and this in fact mathematically meant that they were nearly all receding from the earth at speeds exactly proportional this is really cool here to their distances so that the further you went the further they appeared to be the further they were were the faster they were receding so the redshifts were it more and more exaggerated so this wasn't a um a case where all galaxies were just receding at equal velocities he was noticing that the further away ones were really going fast and this was kind of hard to believe and in fact a Hubble didn't even believe it until he uh as far as I know until as far as I read both him and lamatre both they didn't quite it's kind of like plonk and interestingly Einstein was the one who uh you know he he kind of latched on to it he realized he made a mistake trying to correct and make his Universe static with his cosmological constant balancing gravity um because he he removed the cosmological constant which allowed for the expansion of the universe but it was interesting that um bahubal and lamatre both they did the math and they even made the observations but they couldn't quite come to terms with the fact that this might physically mean or this might actually mean the galaxies were physically receding away from us like that just in all directions it's thought even from at the end he um he still considered them just apparent velocities he he thought there was as of yet a still undiscovered phenomenon like some some reason other than the actual galaxies running away from us that could explain why their lines were so redshifted like that and in 1941 the Hubble reported to the American Association for the advancement of science results from a six-year survey at the Mount Wilson telescope in fact his own results his own data did not support the expanding universe theory but meanwhile like I said Einstein grasps fairly quickly that he'd made what he even called his greatest blunder by simply not predicting the expansion as his equations showed him and predicted so they they either predicted it was basically like a static Universe would have been a ball sitting on a hill and it would have either had to inevitably it wasn't natural for that ball to just stay there it was a very um unstable situation and so he Einstein's equation said that it's either going to roll this way and everything would collapse or it would roll this way and everything would be naturally just expanding and so he felt like it was oh such a you know such a missed opportunity but um within a few years this 2000 year old belief in a static universe perfect and timeless was shattered and it was now accepted fact this equation combined with the well-fitting Friedman equations Hubble's equation was basically it was basically a linear relationship showing that velocity increased with distance cemented the theory of the expanding universe but what's interesting about Arthur key figure here lamatre was that he wasn't done Noble had shown that the distance to galaxies were way further than sitting nearby Our Stars and he whether he believed it or not he showed that the universe and those galaxies those distant galaxies were not only distant but they were continuing to expand away from us but lamatre was still at it he was a he was a Roman Catholic priest and I can't get this out of my head that he he would have been inspired from a religious perspective to keep pursuing these cosmological ideas and within two years of him and uh Hubble you know predicting and discovering the expansion of the universe or the expansion of the recession of these galaxies away from us in 1931 it was a breakthrough year for lamatre and along with Friedman who'd since died he'd finally received some recognition for pioneering a relativistic cosmology in which he explained the observed redshifts of an expanding universe but he pushed this idea even further he explained it as this this flow of energy this flow of space that would have been repelling the galaxies away from one another and he suggested that maybe this was evidence that if you ran the projector backwards in time this expansion of space repulsion would turn into a gravitational attractor meaning that there might be an initial creation like event things would have gotten closer the universe in aggregate would have heated up um and they ultimately all matter then ultimately all matter would have coalesced and superimposed at some singular what he called primeval point Point some Primeval Atom and this in the early 30s was the first speculation about the Big Bang we can tell by our track record by now with copernicism Newton and Einstein um Apple the community wasn't eager to embrace this and it took almost 30 years for them all to finally grasp the implications in the fact that okay there was evidence of this and we'll be talking about that in a minute here and it's harder to imagine that this wasn't because he was a priest he had some religious inclination and I think that's a beautiful thing because well I don't think it necessarily goes against a creation like event but you know regardless I I don't want to oversimplify it I don't think it is that simple and it doesn't even mean that the Big Bang was the only iteration of the universe it's nonetheless it's fascinating that the Universe isn't this you know kind of almost dull perfect infinitely static steady state thing it actually is very Dynamic it exploded from some point it was much hotter it evolved the things in it evolve and uh we're in the process of figuring out a whole lot more about it so then you know within about 10 years of that we had so it's crazy we have within like within just 20 years we have Einstein coming out with general relativity we have Hubble discovering the EXP the the that the universe is these galaxies are lying far outside these local stars of ours so the universe explodes in size and then just a couple years after that it starts literally exploding in space and the expansion of space propelling galaxies apart then we have the idea that maybe this expansion is the residual momentum of space from an initial explosion like creation event out of a of all matter and energy out of a single Primeval Atom [Music] and then within just a few years from this this Swiss scientist astronomer Fritz Wiki in 1937. I was looking at galaxies he's looking at Spectra and observing that they're rotating way faster than they ought to be well he's looking at clusters rather and he's looking at the movement among clusters you can see them blue shifting and redshifting or you know less red shifting and more red shifting as they uh swirl around each other and he's noticing that the movements are way way too much for The observed Mass yeah because Spectra of galaxies look similar to Stellar Spectra you know they are the combined light of billions of stars so you can roughly astronomers are able to they have some methods by which they can estimate the rough mass at least within a magnitude of the right magnitude of individual galaxies and these galaxies weren't obeying that law they were they were moving in such a way that looked like they had they needed at least 20 times more Galaxy Mass in them based on the gravitational interaction among them and so what zwiki hypothesized which I'm noticing all these things so many scientists and I think rightly so you shouldn't be eager to speculate without proper evidence and zwiki was one of them he said he was along with the bunch he went in in the same manner as the others you know being reticent to think that something exotic or a crazy anomaly is the norm he says that there might be just a great deal of non-luminous matter in the Galaxy clusters and would he initially meant I believe was just you know matter that we couldn't quite see and matter that was probably ordinary matter but just invisible in the sense that it wasn't lit up like stars so we couldn't quite detect them visibly but this became known as dark matter this non-luminous matter and within about 10 years observed Dynamics within galaxies everywhere astronomers looked could be explained only if there was way like 10 to 30 times more gravity in them than the galaxies light was showing 40 years later in the 70s scientists even calculated that um that rotating Galactic discs containing only stars and other material like gas and dust and planets should actually become unstable and swell into spheres and not be these flat rotating discs that they are now if they didn't have all this extra gravity in these Halos corralling them into flat discs so since his Discovery is Wiki in the 30s the theory of dark matter has actually been a pretty prominent aspect of all major cosmological models since then it's a thought that maybe most galaxies in most of the universe in fact is made up of dark matter although interestingly I found that I came across a 2003 study that said four galaxies and GC 821 3379 44 94 and 46 97. were found to have little to no Dark Matter influencing the motion of Their Stars within them and the reason behind this dark matter this lack of dark matter is unknown so there's actually a whole video I want to make on anomalies like this that either disprove or just don't go along with the current theory that I found it's a if you guys want to check it out just go to the Wikipedia page of I think it's unsolved problems in physics it's pretty uh it's pretty amazing to watch until I read through that so then just a couple years later what would happen out of La matra's theory of the Big Bang was that you know by the 20s and 30s particle physics quantum mechanics had become full-fledged and was making predictions and discoveries of new particles and so they were understanding they were starting to understand what happens at high energies and how particles matter break down in the forces like the electromagnetic Electro weak Force which was the combination of the weak Force nuclear force and electromagnetism that used to be unified at high enough energies that is Unified and later on it would be found out that the strong force holding protons and neutrons together in the nucleus actually is a third phase transition or I guess the second one you'd say creating the Unified Atomic Force forces altogether and this this understanding of quantum mechanics and particle physics allowed them to make predictions these people who were proponents of the Big Bang model La maltre's Theory they were saying that well the universe was hot enough and everything was condensed enough that we could I mean we should be able to have an idea of the rough um state of things if it gets hot enough at certain energies certain features will appear and certain things will be able to be observed in one of them was that receding wall of white light this this essential essentially continuous infinite as far as the universe was large field of black body radiation still fizzing white hot with the initial um Keat from the explosion of the Big Bang popping into existence gradually over hundreds of thousands of years cooling down and uh and it's not that this field should be cool enough now that it's far and Far Enough away that it's shifted into the far infrared and even microwave regions and that's exactly what happened in the 60s 64 it was discovered that the Cosmic microwave background is the most perfect black Body Curve found in nature that exactly 2.7 degrees Kelvin it peaks in the microwave region and and um I always thought it was just a something they found and they kind of just tried to come up with a theory but it's actually it was actually a prediction and they actually uh discovered that it matched perfectly with other predictions and the more they measure it they have the Penzance and Wilson description here we can see um or measurements it's real weak and then the Kobe satellite I mentioned in the 90s gave a much more precise measurement and then in the 2000s Planck or W map and then even further in the uh what's I believe it's still out there orbiting the Planck measurement the flock satellite measuring these these uh background anomalies from the early heat uh just the radiating environment of a steady glowing reverse I thought it was relevant here to take a brief detour in space telescopes and why is it that they're so important I mean this graph here we touched upon it before the atmosphere absorbs a ton of different wavelengths and this graph here perfectly illustrates that see here in the radio spectrum the essentially the background that touches the ground here means that it has a the atmosphere is fully transparent to this section of the electromagnetic bands so it's only partially transparent to visible it reflects a lot of it back about 50 percent and then a ton of infrared over here is um only sparsely again available like a little bit around the 20 micrometer band but then this huge chunk all the way through the microwave and far infrared is completely opaque meaning it does not allow light to pass this particular type of light here to pass and reach the ground so they have telescopes like the KHAK and and these and these ones in Chile and other mountain tops around the world of course are high up enough where they're not having to um they can pick up more infrared radiation because it's not going through as much atmosphere doesn't completely go extinct but you can see the the gamma ray and X-ray and UltraViolet range the infrared and then the far radio but that's not really that big a deal um because it's easy to make massive radio telescopes so it's really just the x-ray some of the visible that's why Hubble is able to see so much better than most telescopes at least as of recently and until recently rather in the new Advanced Electronica digital uh error correction called Adaptive Optics thank you script right there um yeah that's these telescopes in these ranges here x-ray through infrared are really important to send out in the space it's amazing to think that um well it's amazing of track ideas the first ideas in how they come into fruition because there's always these dreamers and thinkers that of course put things in in writing and put things in the air before they get made and the idea has to come from somewhere and oftentimes I found it's it's from ideas they've been floating around for a long time and then Newton was possibly one of the first to consider an artificial satellite he had a it first published mathematical study of the possibility of an artificial satellite as a cannonball just a thought experiment to explain the motion of natural satellites in his principia Mathematica 1687 stating that a cannibal within the velocity initial velocity would be able to shoot out you know have enough altitude that it completely relieves the Earth's atmosphere and as it falls it would be going so far it would never it would go and overshoot the Earth itself and what that translates to is in Orbit actually so it wouldn't it wouldn't lob up and hit the ground they would be going so far that by the time it came down it would follow the curvature it would still be under the influence of Earth's gravity but it would follow the curvature of the Earth itself going so far beyond it that it would fall into an orbit and therefore it would become a satellite and then a little bit under 200 years later another instance of probably the first [Music] true discussion of a telescope outside the Earth was by Wilhelm beer and Johann Heinrich madler discussing the advantages of of an observatory on the moon and then some fiction but I ever hail the brick moon in 1869 Jules Vern's Jules Vern's the Belgium or the begum fortune 10 years later depicted a satellite being launched into orbit and then in 1903 [Music] Constantine sokovsky published exploring space using jet propulsion devices and this was the first academic treatise on the use of rocketry to launch spacecraft and then much later approaching the actual date that we started launching rockets in to space in 1945 in an article English science fiction writer Arthur C Clarke described in detail the possible use of communication satellites for mass communications that's so amazing he explained it perfectly he has three geostationary comp satellites that were Within range of each other the whole time so anyways 1946 I thought that was just cool to track the you know quick trajectory of how long it's been in the air to make these then Lyman Spitzer he's one of the the predecessor to Webb as far as an infrared telescope goes was named after Spitzer because Spitzer was he played a major role in the birth of space telescopes in general in 1946 a year after Arthur C Clarke's article Spitzer published astronomical advantages of an extraterrestrial Observatory and then he discussed the two main advantages that it would have over ground-based telescopes you know the angular resolution first would be one you wouldn't have any atmospheric distortions and then the second would be that you wouldn't have any atmospheric blocking from ultraviolet lion in the third he made maybe mentioned but didn't think about would be if um would be basically not being bound to the Earth so you could always have constant observation of a particular object for way longer than just you know 10 hour 8 or 10 hours however long it might be visible on the surface as the Earth rotates so over the 50s and 60s we had the space race and tons of satellites starting to go up and gradually it became more and more apparent that non-optical telescopes were going to be extremely important for astronomy in the 60s we had the um space-based astronomy because it was initially just satellites and then of course manned satellites 60s and 50s and and then with James Webb instituting the prioritization of pure science experiments along with many other people but he was a huge factor in it um along with the Apollo missions we had these pure science initiatives launched by NASA this was the birth of the Explorer Program and a woman named or an astronomer I I say a woman because I saw her picture here Nancy Grace Roman um and she's called the mother of Hubble she's uh she was the chief NASA chief of astronomy of these early scientific missions she got to be seen here see a picture of her holding an early prototype of Hubble but she's considered the mother of Abu and Spitzer is considered the father because they both were proponents for getting a you know really putting some serious money into a telescope going far beyond these small little you know foot wide telescopes that they had sent in the space before then in about 30 years later we'd see the birth of Hubble in 1962 a report by the U.S National Academy of Sciences recommended the development of a more advanced Space Telescope as part of the new NASA Space Program to the Moon 1965 Spitzer was appointed as head of the committee and given the task of defining scientific objectives for what would become Hubble a large Space Telescope supposed to be 10 feet in diameter that got scaled back a little bit the launch slated for 1979 that got scaled back 11 years but that's for another time there's been about 100 space telescopes since the 60s that have been launched and we um we saw our first strictly infrared Telescope launched in 1983 and this inaugurated the space-based infrared astronomy which blew open the minds of scientists who realized oh yeah there's a ton of infrared radiation pouring in from space this was called IRAs the infrared astronomical satellite joint Mission by the US UK and the Netherlands too and this was a a really accelerated further future missions and we had the iso that would be launched about 10 years later and then 10 years after that we had the Spitzer Space Telescope this um detected about 30 350 000 infrared sources cataloged increase the catalog number by about 70 percent looked gave us the first look into the core of our galaxy and of course showed that you could penetrate gas clouds and Dusty circumstellar discs you know produce stars that we just couldn't see from Earth or in just visible light in general and this made it extremely important to get New Missions off the ground and these infrared telescope missions throughout the 80s and 90s really planted the seeds for the importance of a much larger much more sophisticated telescope that would ultimately become the James Webb it actually um so the first exoplanet wasn't discovered until the 90s officially but data from these because there's the way telescopes work I found out is that they just take tons of data and of course they make images but there's also a ton of data within the images and um for every image you see there's you know hours and maybe gigabytes of of uh data and other images that go along with it and over years these data get probed in mind and sometimes there's objects in the images that just weren't thought to be looked at until later another telescope more sophisticated looks at it and see something there and you want to have to go back and compare and so it's really important to have these massive archives of data and it turns out that in the 80s one of the exoplanets discovered in the late 90s was actually imaged but it was just a little too faint to be recognized as an exoplanet back then by our IRAs but um just makes you wonder what kind of you know what information were already aware of we're just not aware that we have it on record and then in the 90s of course we had the iso and that's the infrared space Observatory a strictly European Esa Mission and this was a thousand times better in sensitivity and a hundred times better in angular resolution then I rest and of course Jamie Webb is probably about a million times better this made uh some amazing discoveries though ISO detected the presence of water vapor and star-forming regions indicating that you know that's definitely a way we could have gotten water on our planet um it was able to locate several protoplanetary disks of material around Stars which are considered to be the first stages of star formation detected old dying Stars too it's um with uh with planets forming around them still so it completely contradicted theories that planet formation was only possible around young Stars and yeah there's so much other cool things but um I think maybe one is ARP 220 the most luminous object in the universe was discovered by ISO and revealed that the source for this enormous emission of infrared radiation is an outburst star formation [Music] so dark matter is um a huge part of the universe and we still don't know what it is we've been speculating it about it for almost 100 years now the current cosmological model of the universe is called the Lambda it's called the Lambda lcdm model the Lambda cold Dark Matter Big Bang model and the cold part of the dark matter is indicates that the matter the dark matter doesn't re-interact with regular normal matter or the radiation the light coming off of normal matter as well so it's um it's it's definitely a a dark foreign substance that we haven't detected yet and particle accelerators on Earth are really one of the huge hopes is that one of these days will be able to detect some signs of it in a lab [Music] and uh we're gonna see now we're going to talk about dark energy and how that's revolutionized cosmology Hubble only was looking through Optical you know old-fashioned telescopes we'd say and uh came up with his theory and turned out that that theory of constant expansion held true only up to a certain redshift at which the universe appeared to be expanding even faster than just a constant velocity it now appeared to have an acceleration to it so in the mid 90s Hubble started really making strides in astronomy and cosmology once it got its lens fixed but let's talk about where cosmology went once lamatre was Vindicated in the 60s from his 1930s hypothesis about the Primeval Atom the Big Bang his first being the first one to talk about the Big Bang since then um in the 60s when penzius and Wilson discovered the first evidence data of the cosmic microwave background we realized okay this was predicted from lamatre's theory about the Big Bang where if it did come from a uh a single point of origin then there would be this this state of the early hot and this is really important here I I never had really heard or maybe paid attention to it but this idea that what I find fascinating is the idea that space-time itself if it's expanding that means that further back in time it gets more and more condensed and that doesn't mean the space between matter is is just um it doesn't mean that particles are further apart or doesn't just mean that it means that the space the fabric the the whatever the the nature of space-time itself is the thing that bends and distorts light through heavy massive objects whatever the nature of that is that thing that metric itself condensed and it means essentially that the radiation emitted from galaxies of the earliest and furthest galaxies was emitted since then the space across and in which that light is traveling has expanded and so an interesting effect that cosmologists all agree upon right now as of now until James went breaks this whole theory is that the galaxies way in the past because space is accelerating an expansion they actually the radiation the light coming off those distant galaxies that are now you know 30 billion light years away from us appear larger than they otherwise would in a universe that has not been expanding even in Hubble's Universe of constant expansion those galaxies would look much physically smaller on the sky but because of the actual expansion of space they are magnified not even through gravitational lensing or anything like that that's additional magnification these galaxies are just magnified because of how far how old the light is and across how much expanding accelerating expansion of space they've been traveling and because the light another fascinating thing to think about is that the way we view the current Paradigm of the universe is that light is connected with space-time itself so it it expands as space-time itself itself expands so if you have a a wavelength with a frequency of a billion Hertz that frequency as it travels across billions of light years of space over billions of years that frequency is going to go and get shifted to a lower longer wavelength a lower frequency I think at the furthest distances it is a shift of a thousand is it 10 times more than a redshift of one it just corresponds to a different distance yeah I think so so yeah it could be shifted from a billion hurts it's my understanding in physicists I mean if you're watching this and you're a physicist you're definitely not watching it for my expertise so I guess that won't feel too bad about making some minor errors here hopefully it's not too egregious if we have a billion Hertz basically it might shift it might downshift to Red downshift redshift to maybe 100 million Hertz it's just astounding that that's the nature of our universe space-time itself expands and distorts not only distorts the size of but it slows down the light being transmitted across space-time so that light so those galaxies and things in those galaxies appear I think something like twice's slow as they actually happened to us across 13 billion years of cosmic history in 30 billion years billion light years of distance expansion expanding space the the the rate at which things happen appear to go about twice as slow it was really important to know that although we hear a lot about dark energy that wasn't even a theory because it because its effects weren't observed until Hubble perform some deep fields in the late 90s and until then throughout the 70s 60s 70s and 80s with all scientists had all cosmologists had were the theories of cosmic the cosmic microwave background or sorry the all the observations they had to go on were the the two biggest cosmological phenomenon were other than observing galaxies and their Dynamics was the the the cosmic microwave background which said told us a lot about the very very origin the very first light the furthest back we can go the the opaque wall it's Beyond which we'll never be able to see so it happened everywhere but as the universe evolved it evolved into stable atoms locally and then of course it takes the light time to travel from distant objects towards us so it appears like it the universe well it's basically we're seeing the universe as it was at earlier stages of its Evolution the further back we look until the earliest possible stage we can ever see is this sphere that was 40 million light years away 80 million light years in diameter and has now expanded to 93 billion light years in diameter about 46 billion light years away that's the boundary of the observable universe it's not the boundary we don't even know if there exists a boundary of the universe but that is the particle Horizon of our universe that we exist Within so until the discovery of dark energy in the late 90s all we had was the cosmic microwave background and this knowledge this this observation of galaxies that move faster that appear to move with more gravity and under the influence of more about 10 to 20 times more gravity than their luminous matter suggests so that's why we hypothesized this dark matter and that that influenced the cosmological models that have been created ever since we only thought hey the ordinary matter was about I think something like 20 in Dark Matter was like 80 percent nowadays well let's just put it there until we discover what Dark Energy really is and how it came to be known but um I think Harvard astronomy Professor I mentioned earlier Abby Loeb he has been on Lex Friedman's podcast I think once or twice and he's been on a couple other Dr Brian Keating he's been on that podcast a couple times he's a really interesting guy to listen to talk about aliens or the early cosmology I would highly recommend him he said it's tantalizing to contemplate in his book the first galaxies he said it's dental and tantalizing to contemplate the notion that galaxies which represent massive classical objects 10 on the order of 10 to 67 to the 67th power atoms that many atoms it was in unimaginable amount in today's universe might have originated in subatomic quantum mechanical fluctuations at these earliest seconds of the universe before inflation [Music] so we had in the 1980s before dark energy was known Sky Allen Guth was looking at expansion of the universe and wondering why why gravity in the universe hadn't contracted it so even though we had he he said that even though the early Big Bang because inflation wasn't a thing and the earliest models of The Big Bang Theory didn't incorporate the inflation that I mentioned in the beginning of the universe in the beginning of what seems like happens the length of the universe now what I mention the beginning were it swole swelled up from the size of a you know DNA to 10 light years across or the size of uh cell to was it 110 000 light years across that was originally not until the 1980s that was not a part of the Big Bang model the Big Bang model was a an expansion of the universe out of a single point but it didn't have that other additional component of inflated expansion over the you know over a millionth of a second that inflated the universe right after right around the origin first trillionths of a second and then the universe stopped inflating that that inflation stopped continuing it just expanded the universe began a trillionth of a second later or so it inflated at an even faster rate and exponentially just tremendous rate that we you know I tried my best to explain 10 to the 78th power that's literally a 10 with 77 zeros coming after it um that's that's an enormous unimaginably enormous scale of inflation and then from there the residual momentum of that inflation apparently kept the universe expanding that's that's the current theory but back in the 1980s before inflation was hypothesized we we just assumed the universe kind of expanded at a pretty constant rate and so this cosmologist Alan Guth was wondering why gravity hadn't at least slowed the expansion if not collapsed you know began a collapsation of it altogether the universe and so throughout the 90s the 80s and then the 90s when Hubble began looking uh began showing cosmologists and astronomers that oh we can look way further back than we realized the goal was actually to find deceleration of the universe at the largest scales it was to say okay if unless there's some other Force keeping the universe propelled apart there needs to be some sort of slowing down at the largest scales we should see galaxies start to appear less redshifted and you know the rate at which they redshift should start to decrease at a certain point and they look at supernovas distant supernovae that shine brighter than their entire Galaxies for a few days or weeks or hours to tell them how redshifted um well how far away certain galaxies are and then they can look at the redshift and say that okay these are an appropriately mounted appropriately red shifted Galaxies for how far they are away or their velocity is way way more or way less they're looking to see a deceleration they were looking for velocities much less than the local receding velocities of galaxies within you know a billion light years or so and what happened was the exact opposite in 1998 Hubble helped discover a new kind of energy a new feature of the universe that really completely overshadowed any energy contribution that matter and even dark matter which previously in previous theories had been up to 60 or 70 percent of the entire universe's energy density it overshadowed that by taking up now it took the 70 percent of the entire total universe density and what's another remarkable what's another remarkable uh a testament to just how sure of ourselves we get sometimes was that cosmologists really thought that they had almost figured everything out about how the universe evolved all the rough parameters once they it's this inflation um because so there was a lot of anomalies I don't even understand so I won't pretend to here about the a lot of unexplained gaps in their particle physicists and cosmologists understanding of the first few minutes of the universe based on what the you know based on what particle physics the known uh dynamics of particles at higher energies kind of set or predicted and this inflation concept by Alan Guth cosmologist guy and who came up with it in the 80s really solved a lot of these a huge gap in in just how the universe everything I've mentioned in the beginning just how possibly quantum mechanical perturbations could have um Scott sewn in to the the fabric of the universe at such an early time in how dark matter because it's cold and inert and it doesn't interact with regular matter in the radiation that was being spewed off it for hundreds of thousands of years in the beginning they it was kind of like a perfect seeming like a perfect Theory the inflation because they were wondering essentially what happened was they were wondering why matter had even had time to condense into galaxies even after billions of years according to their models matter would have been so hot that the radiation from matter and it does uh light does actually impart force on things that it hits It's a small Force but even spacecraft when they're um when scientists are calculating trajectories of spacecrafts and their orbits they have to take into account that the sun's energy hitting them the light just the the photons not even particles that it emits is actually putting a force on the side of the spacecraft that is facing the Sun and so there is an outward Force even though it's small but of course like we said I think it's something on the order of a thousand times more photons than all the stars in all the galaxies in the 14 billion years of the entire universe a thousand times more than that amount of photons was how much light was emitted by this Cosmic microwave background at the time of last scattering um so that tells you it's a lot those photons add up to quite the force on the original field of hydrogen in the universe that went on to make up the stars and you know matter the rest of the matter of the universe this radiation would have smoothed out the distribution of matter so much that even gravity itself even over 14 billion years wouldn't have had time to allow the Stars to condense and or the matter to condense into the first Stars so they're wondering how star formation and Galaxy formation got underway so quickly in the beginning and this idea of inflation helped explain that by saying that the universe explained expanded so rapidly in such a brief moment of time so soon after the big bang originated everything that it froze into place through quantum mechanical fluctuations that just naturally exist and in random fluctuations in vacuums in just the nature of in into the that are just a part of reality at small enough levels because the universe expanded so rapidly these fluctuations that rule in the realm of the small Quantum they got froze into place and dark matter the theory the reason they call it cold is because dark matter is not hypothesized to interact or be pushed by that Force imparted by the photons by that massive field of photons that was circulating around in the early universe so dark matter cold dark matter was actually able to be condensed into the pockets of higher density that the quantum fluctuations froze into space and then it was around that over a few you know over millions of years it was around that matter that that dark matter those dark matter Pockets nodes in the universe that the filaments that make up the cosmic web on the grandest of scales the filaments of matter that it began to form these superclusters of galaxies and so it's thought that um actually it's literally what this is right here it's just really interesting to me to understand that we thought we had it mostly figured out and there's been multiple times in history where we've thought we had it figured out I think I forget what it was I think in the 1800s it might have been Lord Calvin it was one of the famous famous uh scientists of European the enlightenment age thought that they basically just had a few small gaps in our scientific knowledge to fill in this is way before quantum mechanics in the UV catastrophe and um relativity was even a thing 100 100 or at least 50 years before there's been an arrogance in science and just it's almost understandable because of how much we know and how well our mathematics describes the Universe I mean think about that we one of the LaGrange points uh or sorry LaGrange whom the points are named after the famous French mathematician he found out about those he mathematically deduced those based on Newton's laws of gravity in the 1700s and we didn't we weren't able to experimentally confirm them by literally putting satellites there or observing Trojan and where they uh Hellenic I forget one of the other ones called groups of asteroids circling orbiting with Jupiter in front of and behind Jupiter in its orbit at those LaGrange points we weren't able to um test them out experimentally and we literally are sending satellites there nowadays and this mathematics is so powerful and physical experiments are so revealing about the nature of the universe we've had just a numerous instances where we thought we were really pretty much done figuring out the universe and now here we have another another instance of that almost being the case we just thought we had to kind of fine tune some parameters about how the universe is probably slowing at the largest scales and in 1998 Alex philippenko he's just such a he seems like such a cool easy going guy such a fun guy um him and this guy Rhys Adam Reese who actually won the Nobel Prize for this philippenko didn't it turns out in that him and Lex Friedman talked about that in the interview but I guess there was a team of like dozens of people so it's you know Philippines like yeah I get it you know I wasn't you only get only three people get awarded for any specific Discovery a maximum of three rather so philippenko wasn't in the top three people being important for the discovery but in the late 90s as they were looking for evidence of cosmological deceleration saying that gravity from dark matter and matter mostly dark matter makes up you know 70 at the time 30 percent dark matter or something like that should have should have slowed the expansion and as they're measuring the supernova they noticed it was redshifted not less but about 15 percent more than they expected and so this blue cosmology apart yet again so the universe went from being just a couple thousand light years across to two million to a few million in the galaxies were expanding away to billions of light years across but kind of at a constant expansion from an event that happened at the beginning of time to now acceleration of expansion at the furthest most extreme distances that indicated that there was an active element in the universe completely unknown and undetected before 1998. causing the space time to continue and even Quicken and its expansion this became dark energy it was an acceleration of space-time it's really fascinating I'll have to do another video about just all the other stuff I'm skipping over here about the how we know how we can use type 1 Supernova because there's different types but there's one in particular that a famous Indian scientist Chandra sakar derived from quantum mechanics in the atomic physics actually about the way Stars about limits of the mass of certain Stars before they can't handle their own pressure the gravitational pressure and they explode it uh tells scientists that a predictive amount of Luminosity will be given off by stars that explode in this specific way called type 1A supernovae once they pass what is now called the Chandra secar limit in 2003 observations of the cosmic microwave background and the redshift intrinsic to it confirmed this expansion this accelerated expansion then uh 2011 a Nobel Prize was given the Adam Reeves Brian Schmidt and Sal Perlmutter for the discovery of dark energy But Not only was and I think the point I'm trying to reiterate over and over again by saying that I'm trying to find the motivation the the the truly inspiring interesting insightful the the fascinating [Music] and exciting aspect of James Webb I'm trying to convey what I've found is that there's so much we do not know about the universe in our existence and there's so many more Mysteries that keep opening up with new discoveries that James webble will uncertain will most certainly push further so it's John Mather being the lead scientist for James Webb he's been interviewed quite a bit and in multiple articles and interviews he's given he stated that um even though there's all these expected things coming from James Webb based on its abilities and technological advancement of its instruments there's also the unknown aspect which is why I opened this video with the quote by t.h Huxley about the unknown John Mather says it's not just what we know web can do but it's the things that we haven't even yet thought to expect that it will most of the most undoubtedly discover just the way web or Hubble uh discovered the universe was lit up and redshift six through its first deep feeling and then a couple years just a couple years later we're used to things you know sometimes happening at least big breakthroughs not happening until you know every 20 years but it's like just three years after the first Deep Field we discovered that there's a an energy in the universe intrinsic to space-time so something that physics essentially missed on Earth in our experiments in particle accelerators here that makes up 70 percent of the entire energy of the universe and affects the way galaxies evolve and and so that wasn't expected with the Hubble you know these discoveries it was expected that we would find more about the universe out but these were unexpected discoveries and so it's natural now to expect Webb to make some observations that are kuna really Challenge and that's why they built it in actually to a lot of the reports web is let's see I have a one of Webb's primary goals is to either verify or challenge the current Benchmark model for the age of the universe the Lambda gold dark matter Big Bang Theory this is a so we measure Z the redshift but we it's it's depending on what model of the universe what mathematical equations and parameters what values of the variables we put in those parameters are that tell us how to interpret the redshift into distance and time and also more esoteric things like the curvature of space-time that we mentioned a little bit earlier so we're all of these things are expected to either be either confirm the current model which is 70 Dark Energy you know 30 Dark Matter roughly 25 5 regular matter but now we're getting wiser in our old age and a lot of people are outwardly saying yeah maybe Webb's goal isn't to confirm it but actually rattle it up and and you know shake the foundations of our current cosmological model and cause make a need for a new physics even so it's really uh it's really exciting to hear that happen and so just 20 years ago we had a new completely unexpected aspect of the universe called Dark Energy coming to play and what's even crazier is that like I said cosmology and physics have been going hand in hand trying to reinforce each other's theories and if one if there's huge discrepancies like between gravity and quantum mechanics um that's clearly an area we have to reconcile and one thing about dark energy is that uh and David Butler goes into it and explains why we have a fairly good grasp of maybe the origin of dark energy and it's it's essentially that their it's essentially that the the nature of space itself at the smaller scales has these forces these quantum mechanical field energies and other energies too always bubbling around and bubbling in and interacting with each other at different nodes and um occasionally they'll they'll create a spike in energy and this as the universe has expanded from residual inflationary expansion the momentum left over from that for about 10 billion years expansion it happened pretty consistently but at around the 10 billion year old Mark the universe became became expanded enough for enough extra space was added to it that these energies these vacuum energies in the quantum field fluctuations they began adding up over billions and billions of light years you know 40 50 60 billion light years at that point they added up to start accelerating the expansion that was already happening and he actually goes into I'll recommend that to um you know the actual equations behind it so it's not just speculation it's pretty um you know it's mathematically tight but one thing so they they think they have a general idea of it and they have mathematics to back it up except they're off by a scale of 120. uh no no sorry it's a little bit of a difference here off by a scale of 10 to the power of 120. so there's a huge discrepancy quantum mechanics tells us that the source of this vacuum energy might be tiny Elementary particles that flicker in and out of existence everywhere throughout the Universe and various attempts have been made to calculate just how big the effects of this vacuum energy should be but so far the order of magnitude of theoretical estimates and the value required to account for the acceleration observed by the Supernova measurements are off by 10 2 the Power of 120. so although there's compelling evidence that dark energy exists if we have no idea of the source of such a large magnitude of it another fact I learned from David Butler's video Dark Energy's density is very low it's much less than the density than the density of ordinary matter and dark matter but um an example is a it's it's negative gravity of course because it's an outward repulsive Force counteracting the attraction of gravity it can't be observed on human scales we can't observe it we're only observing the effects on cosmological scales of course of you know 40 billion light years and 14 billion years all that empty space in there is the compounded effect the The Accelerated expansion is the compounded effect of this energy taking effect over 40 billion you know 93 billion light years of empty space so this negative gravity can't be observed on our scales because it would take a million years for a meter three feet to expand just seven millionths of a meter so it would take a million years to expand just seven millionths of a meter for a meter to expand by that much more so of course that's not even measurable on anything approximating what our current technology and current human lifetimes exist Within but it's a it's a cool historical note that dark energy approved lamatra right because he did have on top of the theory that the big bang theory that the Universe might have actually been if it is expanding it might actually have been uh come from a single point out of which it expanded he also separately or not separately but as a a completely equal equally amazing feat of of contemplation and then theoretical work he predicted that the Universe was actually accelerating or at least that he outlined equations that predicted that whether or not he actually believed that that was a different story because apparently he didn't he was a couple and didn't really believe that that was a a tangible fact so much as just a way to interpret the data one extra little note I'll add about dark energy is that Alex philippenko was again in the Lex Friedman interview he actually said that maybe given that the inflaton field that caused inflation and then rapidly just dissipated and actually interacted with reality to actually be some sort of causation of matter in other particles after that fact maybe possibly after you what Dark Energy implies is that after a long enough time scales there are other fields other things or maybe the inflaton came is coming back into existence so in other words he's saying he's saying he doesn't know what it is but um that there may be a connection between inflation and the current acceleration that dark energy is causing so that's um that's the one of the main goals of James Webb to see how the cosmic microwave background radiation has evolved into galaxies a couple hundred million years after the period captured by these microwave background missions like wmap Kobe W map and plonk the block telescope [Music] okay so if you made it this far um I guess oh if I haven't put it in the description I'll clear you guys in to uh material I didn't use for the James Webb Space Telescope video I had written this huge well I've written this and a couple other real big background kind of contexts that the web telescope sits within and historically and there's a whole nother one where it's it's I'll probably have to redo it because it's just I don't think I did a very good job on it but uh this was kind of the science cosmology background and context of web and its purpose for existing being made and the other one was a historical um kind of a context of the the concept of light in ancient history and how you know our origins of fire I kind of touched upon it and I left a little segment of it in the actual Web video about our relationship with fire in our earliest philosophies about light and fire and warmth and and how they intertwine with mythology and deities Sun gods and um I mean it definitely wasn't anything uh extremely Illuminating I guess you might say uh in regards to mythology so I don't think it's really worth putting out but I'll definitely touch upon it and maybe if I could do some more research and flush it out some more um it uh it was very cool in in Webb I think I have a I might have ADHD or something but um as I was learning about web I wanted to understand its background and the physics and astronomy and and then I got into the history of astronomy which led me into the history of you know uh astronomy is just goes so far back in human history so that was a subject I started kind of dabbling in and um anyways it was uh it was fun but there was a lot in my final script that I wrote and this is part of that uh fruit I guess of the script that didn't quite make it into the web so I hope if you guys liked this I would love to do some more kind of histories and and Broad overviews of you know astronomy and science um there's a whole nother hour-long segment that I about electromagnetism and its separate specific development out apart from cosmology um just yeah the the train of thought from around Descartes a little bit after him Newton came along on the scene and he became the chief reason why his investigations into light chief reason that for 200 years after him all physicists most physicists thought that light was particulate that needs to be a separate video regardless Newton thought it was I think Newton thought it was corpuscular he thought he was particles so everybody thought it was possibly particles yeah and Descartes thought it was waves one of those two um but the whole after the 1800s the whole history of light is you know it's fascinating how from Maxwell and his equations and and Faraday's experiments before Max bow and then hurts in his lab confirming the existence of radio waves um that Maxwell had predicted and then on up to 1900 when you know Planck had figured out that light had to have had to have a Quantum a smallest amount of energy that it could exist Within uh that like could could deliver I guess exchange between matter particles atoms anyways that whole history is fascinating and I tried to do that obviously I don't retain much of it so I probably didn't that means I probably didn't do a very good job of uh well not only learning it but even what I wrote down wasn't enough wasn't good enough for me to really be able to explain it obviously so that's a whole nother video I'd like to do the whole history of flight but regardless this is my uh really long way of trying to wrap this video up in editing here realizing that it's a chunk of you know existing material that I just didn't get to use for web and so I wanted to say wrap it up by saying thanks for watching guys and uh for just showing yet again um so much gratitude for all of you who do watch who show love in the comments support the channel financially through all the Avenues um you guys it really means a lot and uh and thanks for the well wishes on baby number two we got coming um probably tomorrow as of recording this video so by the time you guys see it should probably be here we don't know whether it's a boy or girl at this moment but we're very happy and um yeah this is a really fun topic and obviously I'm constantly learning more and more about it as I uh make these videos and that's part of the reason why it's so much fun and and meaningful for me to do this and meaningful that you guys enjoy watching it thanks so much guys I'll see you in the next one take care good foreign [Music] foreign foreign foreign

Channel: Let's Find Out

Views: 320,555

Keywords: asmr, science, history, quiet, sleep, study, relax, educational, facts, informative, intellectual, math, documentary, teaching, professor, lecture

Id: U6M7_Pt0d14

Length: 194min 43sec (11683 seconds)

Published: Sun Apr 09 2023