The Entire History of the Universe in 20 Minutes!

this video is sponsored by one dream click the link in the description for a free trial to their great science content if you're like me you gazed out at the night sky and wondered how did all this come to be how did the Earth come to be the Sun the solar system the Galaxy and the rest of the universe you don't need a Physics degree to have this kind of curiosity but some brilliant physicists who are also curious asked the same questions and some came up with powerful and sometimes surprising answers this is the field of cosmology in this video I'm going to try to summarize all of cosmology and answer some of the most profound questions you've probably thought about at some point and I'll explain this visually in about 20 minutes that's coming up right now [Music] it's amazing to think that although human civilization has been around for over five thousand years our view of modern cosmology has largely been shaped by discoveries made over only about the last 100 years it was only in the 1920s that Edwin Hubble showed that there are galaxies outside our own Milky Way galaxy and then showed that those galaxies are moving away from us proportional to their distance this implied an expanding universe exactly is Einstein's theory of general relativity had implied over a decade earlier if the universe had expanded since the time it was formed this implied all the energy we could see including the energy of matter was tightly packed together in an extremely hot dense State at the beginning and had somehow expanded ever since this was jokingly named big bang by Fred Hoyle in 1949 but the big bang was a hotly debated topic until the 1960s when the debate was settled as penzius and Wilson two scientists working for Bell Labs accidentally discovered the cosmic microwave background or CMB which is what we would expect to see if the Big Bang actually happened it's a microwave radiation emanating from All Points in the universe when the universe had cooled to about 3000 Kelvin it's the leftover Embers of the Big Bang today the universe is much cooler about 2.7 Kelvin then in the 1970s the existence of dark matter which was originally theorized by Fred zwicki in the 1930s was confirmed by Vera Rubin she found that the rotation of stars in the outer rim of nearly all Galaxies have about the same speed as the inner Stars it was theorized that this happens because there's a mysterious Halo of matter surrounding galaxies that we can't see that's why it's called dark matter in the 1980s the theory of cosmic inflation was developed by Alan Guth which seemed to solve several Mysteries of the early universe and in the 1990s two International Teams of astronomers found that the expansion of the universe was not slowing down as would be expected due to gravity but was actually accelerating the energy that would cause this acceleration is referred to as dark energy and we've continued this progress into the 21st century for example we have been able to find more evidence supporting these earlier discoveries as well as make new ones such as the measurement of gravitational waves and we've seen a leap forward in the Precision of our measurements of fundamental constants so that is the historical perspective of the progress of cosmology what I didn't tell you is that the true start of modern cosmology happened even before Hubble's discovery of the vastness of the universe it began with Einstein's formulation of the theory of general relativity pretty much everything in cosmology has its roots in this Theory so what is it in a nutshell general relativity treats gravity not as a force which it had been thought to be since the time of Isaac Newton in the 1600s but rather as a result of the geometry of space and shockingly of time as well in fact it introduced the notion that time is intertwined with space and is equally important mathematically what made general relativity so earth-shattering was that it described how mass and energy could change the underlying space and time itself and this change is what manifests as gravity before this space and time were considered to be unmoving unchanging backgrounds on which massive objects were attracted to each other Einstein showed that it's the change or curvature in the geometry of space and time that causes objects to be attracted to each other so much of cosmology boils down to solving the famous Einstein field equation of general relativity without getting into the math let me just give you an intuitive feel for this equation the left side of the equation represents the curvature of space and time space time the right hand side contains all the matter and energy of the universe this is all the stuff that makes up you me the planets and everything around us this equation simply tells us that the makeup of all the mass and energy of the universe creates a curvature in space-time which we interpret as gravity and that gravity in turn influences the mass and energy physicist John Wheeler said it best space-time tells matter how to move and matter tell space-time how to curve all the complexity of general relativity can be summarized in those simple words so with this we can simply plug all the information about matter and curvature that we have spent centuries looking at into this equation solve it and obtain the equations that explain our universe and that's essentially modern cosmology in a nutshell and plugging everything into the equations gives us a model of our universe and we can then turn back the time to understand how the universe looked in the past we know our visible universe is expanding so this means that if we turn back time it will become smaller and smaller so at some point it should be infinitely small this is called The Singularity now many cosmologists don't think that the Universe was actually infinitesimally small at the beginning and that this is likely just a glitch in the limits of our model now you might say hold on why should I believe any of this if you're telling me that there is a glitch in the model that's a valid concern but since the model makes many predictions about this early time which we can test even today we have a ton of evidence that supports the idea that the model works perfectly fine if we ignore the point where the universe is infinitesimally small so what we can do is turn back time to just before this glitch at this point we can say that the Universe was incredibly dense and hot as all of What Becomes of the universe we see today was compressed to a very small size let's say the size of a swimming pool now here you might ask how can the entire universe fit into the size of a swimming pool well we tend to think that this is impossible because we're used to seeing objects which are composed of atoms and molecules and these have a distinct size but you have to remember that the early Universe was not composed of any of this it was composed of only energy at its core all matter is simply energy mass is equivalent to energy even the rest mass of fundamental particles is energy the early Universe was not even composed of fundamental particles as far as we know it was all energy and energy has no size limit in principle it could be contained in any volume you choose the temperature would just be higher at smaller and smaller volume so let's start from as far back as we can go and let the history of cosmology unfold the timeline of the universe can be divided into about six stages the first stage is when the universe started from what is theoretically a singularity 13.8 billion years ago the universe was very small here maybe the size of an atomic nucleus but there's no consensus on this everything we know starts here this is colloquially referred to as the Big Bang but you should know that the scientists the Big Bang is the entire process of how the early Universe evolved not just the beginning we also have no idea what came before the beginning or what triggered the universe stage two occurs at about 10 to the negative 36 seconds there's a sudden expansion from this unimaginably small volume in a process called Cosmic inflation this is when the universe went from the size of an atomic nucleus to perhaps the size of a swimming pool almost instantaneously ending at about 10 to the negative 32 seconds the temperature was on the order of 10 to the 32 Kelvin We Believe Cosmic inflation occurred because it explains some mysteries for example it explains why the universe is so homogeneous why it's flat and why we have a large-scale structures in the universe the quantum fluctuations at the Big Bang would have become fixed after inflation this pool would contain a lot of energy moving around in a kind of soup although all the building blocks of the universe that is about to come could be found here everything was massless at this point that's because the Higgs field had zero potential and had not become massive yet this changed as the universe continued to expand and get cooler this is the third stage or era of particles which occurred around 10 to the negative 11 seconds the temperature cooled to 10 to the 18 or 1 quadrillion Kelvin at this point the Higgs field also gained a non-zero potential and when fundamental particles interacted with this potential they gained rest Mass I have a video on this mechanism if you want to know more details and as temperatures continue to fall to about 1 trillion Kelvin the strong force began quarks combined into larger particles but all except protons and neutrons decayed neutrons also decayed unless they merged to bind with protons the fourth stage was the era of nuclei this happened when the universe was about three minutes old the temperatures dropped to about a billion Kelvin some protons and all remaining neutrons now combine to form helium nuclei by the end of this era the universe consisted of about 75 hydrogen nuclei and 25 percent helium nuclei with Trace Amounts of some other nuclei-like lithium but electrons and protons floated freely because their kinetic energy at these temperatures was too high to allow them to become bound together this abundance of free electrons prevented the free flow of photons so the universe remained opaque at this point this is why we can see no light from this era through our telescopes this changed in the next stage which is called recombination or the era of atoms but this did not happen until the universe was about 380 000 years old and the temperatures cool to about 3 000 Kelvin electrons could now combine with protons and helium nuclei to form neutral hydrogen and helium atoms the observable universe had grown to the size of about 83 million light years at this stage since the electrons were now able to be captured by nuclei they no longer interfered with the free flow of photons as a result the universe changed from being opaque to transparent and this was the first visible light of the universe that can be seen even today it's a form of radiation that emanates from All Points in space called The Cosmic microwave background or CMB this light was originally more energetic but the expansion of the universe has caused this light to stretch decreasing its energy to the microwave Spectrum at this point the universe was mainly composed of hydrogen helium and a little bit of lithium so now the question is how did we get from this to the solar system today this leads us to the sixth and final stage of cosmology the era of stars galaxies and larger structures while the universe is generally homogeneous and isotropic meaning the same everywhere we look it's not exactly the same there are minor differences so for example when you look at the CMB its overall temperature appears to be about 2.7 Kelvin everywhere but our instruments can pick up small temperature differences on the order of microcalvins this seemingly minor difference makes a huge impact on cosmological skills because these differences provide the seeds for the structure of the universe all the fluctuations seen on the CMB can be traced to the large-scale structures of the universe which consists of clusters and filaments consisting of thousands upon thousands of galaxies but in order to form galaxies the universe first needed to form Stars this happened initially when gas clouds consisting of hydrogen and helium combined and gravitational pressure increased over time eventually the pressure becomes so large that condensed balls of gas ignite forming a star and the dark ages of the universe is over because we have light from Stars inside a star hydrogen gases fuse to form helium releasing energy in the fusion process subsequently helium fuses into lithium lithium fuses to heavier elements and so on eventually within the cores of stars we also get the elements needed for life such as oxygen carbon and nitrogen these initial stars were much larger than our sun so they burned brighter and for a shorter time lasting only about a million years and they ended their life as spectacular supernovae explosions as the fusion process stopped after the formation of iron in their course Fusion stops with iron because atoms heavier than iron require more energy to fuse than the energy released so stars begin to die at this stage these Supernova explosions release life essential atoms into the space together with other elements of the periodic table these remnants combined with remnants from many other supernovae explosions eventually form second generations of stars and the supernovae of this generation can form a third generation of stars and so on our sun and solar system are made from the remnants of Prior Stars it was formed when a gravitational Clump formed somewhere with any cloud of gas or nebula consisting of Prior supernovae explosions our sun after it got heavy enough to fuse hydrogen in its core began to shine the leftover debris from the sun's birth consisting of heavier elements formed a protoplanetary disk which accreted over time to form the planets that's how the earth was formed galaxies are vast collections of such Stars they also contain significant amounts of gas and dust but these visible forms of matter do not appear to have enough Mass to keep most galaxies gravitationally bound together scientists believe there's up to five times more mass that cannot be seen because it does not emit absorb or reflect any light this is known as dark matter and scientists believe it played a critical role in the formation of galaxies they believe that dark matter formed gravitational centers in the early universe and these centers were gravitational sinks that attracted visible matter warm matter means more gravity and so these initial Dark Matter concentrations became the seeds for larger structures such as galaxies and Galaxy clusters when dark matter is inserted into the Big Bang model the model quite accurately explains the large-scale structures of the universe we see today 13.8 billion years after the big bang now you might ask why do galaxies spin these galaxies spin due to conservation of angular momentum this is similar to how a spinning ice skater spins faster as they pull their arms in in the case of galaxies gravity is what pulls everything closer together the rotation is also why galaxies are generally flat if you take any object and spin it it will flatten because of this the Earth is not completely spherical either it is flatter at the poles because it's rotating but it's so dense that it still keeps a mostly spherical shape unlike galaxies the exact details of why we have different galaxy types are not fully known now there is one more critical piece of the puzzle that needs to be mentioned it is in fact something that accounts for more than two-thirds of all the energy we observe in the universe remember the cosmological constant I mentioned briefly in Einstein general relativity equation that constant is what we can call Dark Energy it's like an anti-gravity force that pervades all of space-time it turns out that it is causing the galaxies and the large-scale objects to move away from each other at an accelerating rate thus everything that is not bound by a sufficiently strong gravitational pull will drift away over time and the further away it is the faster it will do so so one can say that in the early Universe when Dark Matter dominates and the attractive force of gravity Reigns Supreme things got together and formed structures but as the universe aged dark energy has become more dominant which does the the opposite and makes things move faster away from each other and there seems to be nothing that will stop the universe from expanding at an Ever accelerating Pace until someday we see nothing except the stars in our own Galaxy but this won't happen for at least another 150 billion years so there's no immediate existential crisis and if you want to learn more about the subjects I just talked about in a lot more detail there's a great course that you can check out for free right now on onedream.com today's sponsor because they're offering a free trial and you're already familiar with one dream because they were previously known as the Great Courses plus the course is called the Big Bang and Beyond exploring the early Universe it's a 12 lecture course taught by Professor Gary Felder of Smith college he covers the history of the universe starting from the Big Bang to the formation of the first stars and galaxies millions of years later and then what is the likely future fate of the universe what's quite interesting is Professor Felder also has some interesting speculation about what may have happened before the Big Bang you'll find this and many other wonderful courses on wondering taught by some of the best Educators carefully selected by Wondra that's why I've been a member of wondering for years and you'll see my testimonial at the bottom of their homepage they're offering a free trial right now so you can check out the Big Bang course for free and you can cancel at any time so you've got nothing to lose and a whole lot to gain and if any of your friends enjoy learning as much as you or I do one dream makes a great gift believe me they will thank you so be sure to take advantage of their free offer by clicking the link in the description that link is wonderm.com Arvin that's wondrm.com and you'll be supporting this channel when you sign up so I really appreciate that and if you like this video then smash the like button it really helps us out and if you have any questions please post them in the comment section I'll do my best to answer it I'll see you in the next video my friend [Music] thank you

Channel: Arvin Ash

Views: 112,449

Keywords: cosmology, the universe, history of the universe, summary of cosmology, all about cosmology, all of cosmology, how the universe formed, timeline of the universe, cosmic microwave background, dark matter, dark energy, how did the sun form, how did the solar system form, cosmic inflation, how did the galaxy form, galaxy clusters, general relativity

Id: OUnYkixy3ug

Length: 19min 45sec (1185 seconds)

Published: Thu Nov 10 2022