Dark Energy: The Void Filler

a quick shoutout to Squarespace for sponsoring this video in 1999 Saul Perlmutter was asking himself a question that many of us may have thought of before well the universe exists forever or will it have an end will the universe slowly expand for the rest of eternity or will gravity control the ultimate fate of the universe slowly pulling galaxies together until everything is condensed into one spot a Big Crunch at this time the way scientists observed the universe's expansion was through the study of exploding stars which we call supernovae when these stars died they exploded one of the brightest events in the known universe the Stars expand as they lived their last days and once a certain critical mass has reached these stars eject almost all of their mass resulting in some of the brightest light you'll ever observe there are many different types of supernovae but one particular type always explodes the same way type 1a supernovae they all live the same life explode at relatively the same size when the mass is about 1.4 times the mass of our Sun and they emit the same amount of light this is perfect for observing the far reaches of the universe it's like you can explode the same star but just put them at different distances with this knowledge you can determine how far away any particular supernova occurs as well as how long ago it occurred Saul Perlmutter and his team observed multiple of these explosions they watched these specific stars explode we observed their most important features down so that the smallest detail they eventually had enough data to try and explain the universe's expansion as well as the apparent end of the universe the Big Crunch however the data didn't exactly show what they were expecting the supernovae they observed were much fainter than they were expecting the further away the explosion the less bright it appeared in the sky time and time again they recalculated their results they triple checked all the numbers but every time they got the same results this isn't a fluke what's the big deal well the data showed that the universe was in fact not looking like it was slowing down but rather speeding up the universe is accelerating Saul Perlmutter had discovered something amazing he was even awarded a Nobel Prize for his work but this changed the entire view of not only physics and mathematics but the view of the entire universe we now had literal proof that the universe's expansion is speeding up the problem is we don't know why there's nothing we can see we can't perform experiments because we don't know what to experiment on we don't know what is made from we know it's there we observe its results but we don't know what it is or what it's going to do I'm of course talking about dark energy [Music] since this discovery about 20 years ago we've done at least one good thing and that's to give this catalyst a name dark energy and to be honest it's a pretty bad name for some reason in science whenever we find the existence of something that we don't know how to handle or have no idea how to explain we just say it's dark it isn't dark it's unknown when scientists and physicists the like mentioned dark energy they mean the unknown form of energy that permeates throughout the entire universe which also sequentially causes the universe to expand at an accelerated rate dark energy is literally everywhere to explain imagine a fish tank inside you have fish maybe some plants some logs a couple rocks you get the idea imagine that this fish tank is the universe all of the fish and other things inside the tank are ordinary matter which are things like you and I and everything else you see in life this includes buildings galaxies stars plants dogs planets so on it's all considered ordinary matter however the fish tank isn't only filled with just ordinary matter it's completely engulfed in water the water fills every nook and cranny inside the fish tank and yet all the ordinary matter inside still remains there's much more water than anything else in our fish tank universe the amount of water is similar to the amount of dark energy in the universe now of course the water in our fish tank isn't expanding the tank and the water itself is actual matter but it is a good way to visualize it it's everywhere at once and in relatively the same amount there's a theory about the way dark energy works and why it seemingly causes the universe to speed up to accelerate an idea is that dark energy could just be a property of space it's the idea that empty space isn't actually empty it has energy it's a very small almost infinitely small amount but it's not zero and that's very important and as we know all normal matter all elementary particles that make up everything you know it's already 99.9 9% empty space in itself everything we see is made up of almost nothing there's matter that interacts with the light in that we humans can interact with we can see it and touch it but even empty space something that we tend to ignore has properties that could explain dark energy at the smallest levels imaginable at the size of protons empty space isn't also empty it's full of quantum field fluctuations which represent the smallest amounts of energy changes that any specific point in space to keep things brief and basic they may be caused by virtual particles that come into existence in pairs of electrons and positrons with opposite charges because of this they immediately annihilate one another and they released small amounts of energy this isn't a joke physics Heisenberg's uncertainty principle actually allows for this the law of conservation of energy doesn't apply to an expanding universe on huge scales only in a static environment one that is relatively unchanging this visualization is kind of like an energy map the dark red spots indicate high energy densities this is most likely where these annihilating particles are conducting their business this helps to visualize the fluctuations but the speed is unmatched it actually isn't even close this is running at a septillion frames per second for example most movies you watch are at 24 frames per second and you're able to follow that very well these fluctuations you see are occurring at unbelievable speeds in the vacuum of space the nothingness of space this is happening right now everywhere the amount of dark energy and every cubic centimeter of space about the size of an earring is about 10 to the negative 1/3 the unit's don't really matter here but to compare dropping a penny from waist height hits the floor with an energy of about 300,000 ergs that's over a trillion times more energy this makes dark energy look puny however its most important feature is that it is literally everywhere this tiny amount of energy adds up very quick as the universe expands more space is created like the universe is an infinite plane continues to stretch and stretch dark energy doesn't dilute away over time it stays uniform like I said the easiest way to explain dark energy at this point is to just say that it's a feature of space-time itself it just exists dark energy is stretching the fabric of space-time imagine taking a bedsheet and continuously stretching it out for ever and ever without it tearing now normally this expansion doesn't make much of an effect on local matter like stars and planets and so on gravity is strong enough to hold all of this together however light itself is actually vulnerable to the stretching Edwin Hubble notice this in 1930 when observing the far reaches of our universe Hubble's law shows that when you're observing objects extremely far away in extra galactic space the light you receive is actually altered in a way because of the extreme distance the wavelengths of light are literally stretched out along with space itself the largest visible wavelength that we can see is a deep red and that's exactly what we saw when we look to the far corners of the universe you can still see that today actually remember on small scales gravity is strong enough to keep the solar system and planetary systems held together but on large galactic scales not a chance dark energy has a negative pressure which basically just means that energy is gained as the universe expands there's more of it every second there's more space so that means there is more room for these fluctuations that happen which means the universe will expand faster dark energy at least according to our current calculations will eventually push every galaxies so far away of us at such a high speed even faster than the speed of light the light emitting from these galaxies will travel towards us at light speed but even this won't be enough and the light will never reach us it will spread the universe so thin that when you look out to observe what's around you you won't see anything this is very possible and can actually happen although it goes against your intuition and education on the subject space itself can expand or contract at any rate but the things in space are subject to the cosmic speed limit of light we're incredibly lucky to live in a time where we can explore phenomenon such as dark energy we may have been born too early to travel the galaxy but we were born at the perfect time to explore something even larger the universe we inhabit and the rules that govern it according to physics the entire universe and everything in it us the earth the Sun the Milky Way it can all be described with a few set of equations nobody said they were easy equations but we have them nonetheless the most interesting part however are the so called constants in our equation numbers like pi e the golden ratio the gravitational constant why are these constant where do they come from the bigger question here is are these values truly constant or do they vary over time if they vary then their values over time would have to be determined by yet another equation and this will change everything we know about the universe at the moment if even one of the fundamental constants isn't actually constant it would open doors to entirely new subfields of physics but what if I told you that one of the most important constants one that explains the modern universe may not actually be so constant that when tested and measured in different ways it yields different results our Einstein published his theory of general relativity in 1915 and to this date his theory is still accurate and upheld however the interesting thing is at this time there was no evidence that the universe was expanding a theory that so eloquently describes the universe in our place in it is based off of a static universe one that's unchanging over time but when the theory is applied to a static universe one that Einstein believed we lived in the theory falls apart it won't allow for a universe that is unchanging so he introduced a term that would fix this a number that would counteract the effects of gravity but yet keep the same results this term is lambda or more commonly known as the cosmological constant but in 1930 Edwin Hubble observed galaxies far far away from Earth when observed these galaxies had a visible redshift in their appearance indicating that these galaxies were moving away from Earth and the further away they were the faster they were moving considering how far away these galaxies are the light that emits from them takes a long time to reach us on earth these light waves are literally stretched out and because the color red has a longer wavelength than all other colors it results in a visibly red hue just like we mentioned earlier this is direct proof that the universe is not static but is rather expanding this makes the cosmological constant basically useless this is Einsteins biggest blunder if he had just left this term out of the equation he would have literally predicted the universe's expansion but instead of trusting his original theory that was literally telling him the universe was expanding he introduced a term to stop it it wasn't for another 13 years that Einstein would learn that his cosmological constant was unnecessary and then removed from his theory imagine an extra 13 years on Einsteins life and what discoveries could have been made for 60 years after the discovery of the expanding universe the cosmological constant was set to zero we didn't need a number to counteract the force of gravity to keep the universe static so we got rid of it until Saul Perlmutter showed up and discovered that the universe was accelerating it was growing at a rate that wasn't constant this changed so much in our theory that lambda the cosmological constant is back in our equations today we can interpret the cosmological constant as a property of space itself of the empty space where nothing happens but this actually drives the universe dark energy is already dominating the expansion of our universe and has been for a while for over six billion years for over 80 years the cosmological constant was seen as a failure as a mistake in a useless part of an otherwise perfect theory but today it helps us explain the driving force behind our universe's expansion this blunder is what allows us to understand what nearly 75% of our universe is made of without us even being able to see it it describes something that is hiding before your eyes at this very moment 5% of the universe is the most that we could ever visually see with our eyes 27% is made up of dark matter which is an entire other beast that deserves a video of its own the remaining 68% is assumed to be dark energy whatever that may truly represent based on historical examples almost every theory we've had about the universe was wrong at the start not necessarily wrong but just incomplete as time goes on we get more and more accurate with our predictions and our theoretical models Einstein's biggest blunder is actually one of the biggest ideas in modern physics this kind of proves that science is about making mistakes because the biggest mistakes yield the biggest breakthroughs everything you've ever seen with your own eyes or ever will observe is made of ordinary matter every person you've ever met every planet you observe is made of ordinary regular matter 95% of the universe we inhabit is ruled by forces we cannot explain but each day each experiment each Theory inches us closer to the day where we're finally able to explain a mysterious force throughout our universe and when that day finally comes science and subsequently mankind will change forever I want to give a quick thanks to Squarespace for sponsoring this video Squarespace is a perfect tool for any aspiring entrepreneur creator artist anyone whether you're a seasoned veteran or brand new to the Internet Squarespace makes it easy for anyone anywhere to create a visually stunning website with a catalog of design templates are simple to follow user interface and 24/7 customer support Squarespace is your best bet when looking to build high-quality and efficient websites if this sounds interesting to you head over to squarespace.com slash aperture right now for your free trial and also 10% off your first purchase if you're looking to build your perfect brand online whether it be for yourself or your business look no further than Squarespace you'll be supporting yourself and my channel at the same time [Music]

Channel: Aperture

Views: 353,988

Rating: 4.9298429 out of 5

Keywords: aperture, Dark Energy: The Void Filler, dark energy, what is dark energy, why is the universe expanding, astrophysics, general relativity, albert einstein, quantum field theory, dark, energy, cosmological constant, saul perlmutter, redshift, galaxy, expanding universe, is the universe expanding, einsteins biggest blunder, is the universe static, sir roger penrose, fate of the universe, the big crunch, universe expansion, einstein equations, spacetime, a big crunch

Id: 1YqpyoWFazM

Length: 16min 7sec (967 seconds)

Published: Fri Mar 22 2019

Reddit Comments

[u/salmon10]

Isnt it because of the big bang it's still rapidly expanding? Something exploded and it expands, right?