Dark Matter, Dark Energy and Death Of The Universe - Space Discovery Documentary

it to shreds in a flash collapse in on itself or will it slowly freeze to death scientists are imagining the unimaginable and they're coming up with some wild ideas about how it's all going to end this is the end of the universe [Music] a battle is taking place in the farthest reaches of space no one can see it but scientists are certain that it's happening and that the outcome is grim the universe is going to end it won't happen for billions of years but there is no way out figuring out how it will end is the challenge of astrophysicists around the world they're pointing high-tech equipment out toward the heavens to unlock the secret of our fate the possibilities are frightening in one scenario gravity pulls the universe back into itself similar to air being let out of an inflated balloon the universe goes back to its original size this is the Big Crunch be the end of the universe and a big fireball is all the matter collapses onto itself would be pretty dramatic then there's the Big Chill the universe expands until the nuclear furnaces that power all the stars burn out the universe grows cold and dies a second possibility is actually kind of sad the universe will continue to expand forever and it will just grow into an increasingly cold and lonely place as the expansion removes our nearest neighbors from us and we just end up a single isolated community of stars and galaxies then again there could be a much more spectacular end in which everything is ripped to shreds down to the last atom think of it like a balloon that is filled with too much air it pops it's much more dramatic than the Big Chill and just as fateful as the Big Crunch the universe continues to expand but at an ever quickening pace and the fact the pace is so great that even the space-time fabric cannot hold the universe together however the end comes it will be a dramatic conclusion to understand how it all could end scientists turned to how it began the mystery starts to be solved here at the Mount Wilson Observatory overlooking Pasadena California in 1929 while looking through what was then the world's largest telescope Edwin Hubble makes a strange discovery the universe is expanding Hubble's discovery led to a whole new picture of the universe that it was a dynamic environment and that it evolved it changed in time and that's different from pictures that people had of cosmology previous to that before Hubble scientists said that the universe was static and unchanging Hubble's discovery that the universe is expanding meant it had a starting point a beginning that brought the idea forward that hey what if we ran the film backwards in time and found the point at which that began the Big Bang that fraction of a second when the universe and everything in it exploded into existence from a point smaller than an atom one common misconception about the Big Bang is that we can identify a point in space where the Big Bang occurred but in fact it's more appropriate to think of the Big Bang is a simultaneous creation everywhere of space which is then continuing to expand for the present day scientists theorized that at the moment of the Big Bang the first small particles of matter called quarks were produced they collided to form the building blocks of the universe these floated in a thick fog of hot plasma for about 400,000 years gravity also created at the Big Bang through the particles together eventually creating the first stars and lighting up the cosmos the theory of the Big Bang is a very solid theory what happened at the moment of the Big Bang is still something we're working on we don't really understand if the universe has been expanding since the Big Bang scientists must consider that it will stop expanding at some point the question is how the most obvious answer involves gravity what goes up must come down stars and galaxies and everything else might reverse direction the universe would collapse and what some scientists call a Big Crunch take the top and then see the other handle a model rocket offers clues to how the Big Crunch would work the rocket is like the universe expanding it to space out of the Big Bang an initial bang allows the rocket to overcome the pull of gravity eventually when the fuel is exhausted the rocket coasts a few feet higher stops and is pulled back to earth this is what would happen with a big crunch the entire universe is essentially pulled back to its launch pad the universe itself has its own momentum its own energy it's moving outward but eventually there's a point where possibly the universe will stop that moving outward just like the rocket that we saw and have to fall back in upon itself and collapse again under the force of its own gravity in this scenario the universe could return to its original state just before the Big Bang setting the stage for a perpetual seesaw of creation and destruction the Big Crunch Theory moved to a scientific backburner cosmologists figured out that there must be some form of energy that keeps the universe from collapsing the existence of such a force leads to new theories about what the universe is made of and how it might end and evidence about how this might play out is found in some of the most powerful and mysterious phenomena in the cosmos black holes [Music] predicting how the universe will end involve some of the most advanced technology known to man on a remote volcano on the island of Hawaii astronomers are monitoring a battle in space that is shaping the fate of the universe at an elevation of nearly 14,000 feet the Keck telescopes bring astronomers from all over the world nearer to space for a clearer view of the cosmos they come here because the telescope's work best far away from city lights and as high as possible above Earth's polluted air harsh conditions make it difficult to work here but for scientists in pursuit of the great mysteries above it's paradise this is a remarkable location but of course the air is very thin it's extremely hard to work here but these tasks opes are amazingly powerful but we're ambitious astronomers we don't just start looking at easy objects we try hard to look at the very faintest objects so we can understand the extremities of the universe here astronomers like Richard Ellis are working on a problem that has been all-consuming for cosmologists since Edwin Hubble they know the universe is expanding what they don't know is how fast it will be difficult to predict exactly how the universe will end until they solve this mystery the answers lie in the past now what we were looking what I did the focus on was the V equals 12 okay we get a better focus now that was worth doing an astronomer like myself uses a ground-based telescope as a time machine we're looking back in times to study distant galaxies seen as they were a long long time ago one of the distant galaxies that astronomers found revealed a powerful source of x-rays from something that they could not see it was in the constellation Cygnus and emitted no light but something was there whatever was emitting these x-rays had a mass about seven times that of Earth's Sun there wasn't a name for it so they called it a black hole black holes offer scientists an analogy to how the Big Crunch theory works when certain stars run out of fuel they collapse in on themselves into a smaller and far denser mass that attracts more and more matter just like the Big Crunch the gravitational pull is so powerful that anything that falls near a black hole will be forever trapped not even light can escape it's a mind-boggling concept that something invisible is detectable and offers a view to our ultimate fate this black tarp represents space and space is relatively flat but when you put a massive object into space it curves it this is a penny and notice how it comes into a really beautiful circular orbit basically the black hole tracked it into an orbit around itself and that orbit becomes very circular as it gets closer and now the penny will eventually disappear go inside a black hole Earth's Sun warps space similarly to a black hole only it's a cosmic wimp by comparison the gravitational pull of our Sun is much weaker earth and all its nearby planets are trapped by the sun's pull but it's so mild that it just stays in orbit without being sucked into the Sun the mass of a black hole can be a million times the mass of the Sun or more causing a huge warp in the space around it that consumes everything that comes near that black hole wrapped space around itself and so if material falls near it it falls inside and gets trapped forever black holes exist in isolated areas throughout the cosmos a black hole's gravitational pull is a scaled-down version of the force that could cause the universe to collapse that force is dark matter and dark matter is what scientists often call cosmic glue hi Matthew let's do some cosmology here dark matter attracts other objects where its gravitational attraction it's a positive force there's another force that opposes gravity and that is dark energy dark energy we don't really understand what it is but it's a negative repulsing effect that pushes galaxies away from each other the Whirlpool in Richard Ellis's demonstration represents the gravitational force of dark matter the green dye coming out of the syringe shows how this stuff of the universe collapses under the force of dark matter the presence of dark matter acts as the focus for the gas in the universe bringing structure together this is how the milky way developed as the universe expanded little things merging into big things the positive constructive force of gravity now if this was the only force in the universe the universe would stop expanding at some point in the future and eventually the universe would start collapsing gravity would eventually halt the expansion bring it back together in a Big Crunch yet the universe continues to expand and isn't showing any signs of collapsing this suggests the opposing force of dark energy could be stronger than dark matter but it will take scientific detective work to find out they look to one of the most violent forces in the universe for clues we're studying exploding stars to try to understand if they can tell us the rate at which the universe is expanding these are explosions at the end of our lives of stars not unlike our Sun fuel that these stars have in their centres is spent the star collapses the outer part expands and the star becomes something called a white dwarf white dwarf stars sometimes have other stars orbiting nearby a companion star a massive explosion could happen if the companion stars debris falls on to the white dwarf causing a spectacular fireworks display in the cosmos scientists consider exploding stars or supernovae like in these images captured by the Hubble telescope to be reliable tell tales of how fast the universe expands their brief and bright explosions allow scientists to track the universe's expansion and give them a way to measure its speed essentially they are white dwarfs stars that become nuclear bombs they explode with a certain brightness and a certain length of time it takes a certain amount of time for that brightness to dissipate they are essentially standard candles any one of these will look the same no matter where it is in the universe astronomers measure the distance and speed of these exploding stars by measuring the amount of red light they emit the faster the star moves away from us the redder its light appears the expansion rate of galaxies containing stars like supernovae can then be used to interpret how the rest of the universe is moving outward we know this because we can compare the velocities of galaxies with their distances these are the clues that lead astronomers to answer just how soon the universe will reverse direction and come back together in a Big Crunch or this information might lead to an entirely different conclusion dr. Ellis is looking at clues at the Keck Observatory in Hawaii while the telescope is on the top of a huge volcano he's in a viewing room on another part of the island hey emission lines you're on in the red in the red side at the same time Johan Ruhe char is at the California Institute of Technology in Pasadena California evaluating the light from a distant galaxy that the Keck telescope captured in Hawaii he's looking to see if any of the known elements coming from the galaxy are in the red spectrum and moving farther away we can interpret that as a velocity as how much the galaxy is moving away from us we can really interpret how the entire universe is behaving if expanding interpreting redshift is the cornerstone of the quest to pin down the fate of the universe clearer pictures of the universe that have only been possible in recent years have led cosmologists to conclude that the redshift of distant galaxies is greater than predicted this is startling not only is the universe expanding it's speeding up nothing in the observable cosmos could account for an accelerating universe and yet the data seem irrefutable this has to mean that an invisible force is working against gravity cosmologists have come up with a name dark energy so when the universe was young gravity was the most dominant force and so what we see here is galaxies as particles on the surface of the water bound together by gravity and the point about seven billion years ago dark energy and gravity are pretty well in balance but the universe continues to expand the density goes down and so dark energy starts to take over and lo and behold the universe starts to accelerate so dark energy is now the dominant property of space so the universe started out with a certain amount of energy and we know we're trying to understand how much energy there is and we know the universe is expanding as it as it moves outward with time we also know now that the universe is expansion is accelerating and we don't know is that acceleration going to slow down or not we're still trying to understand that so in understanding what's going to happen to the fate of the universe we have to know how much energy is there how much matter is there the history of the universe is really a battle between dark matter and dark energy these two forces are in opposition and so both the history of the universe and its ultimate fate is really the competition between these two forces the Big Crunch theory was a result of scientists interpreting that dark matter is the dominant force but astronomers now suspect that dark energy might be much stronger if so the end could be dramatic like the poles apart solar systems that pulls apart stars and eventually it grows so strong that it pulls apart matter itself breaks bonds pulls apart atoms and reduces everything to fundamental particles and that's the end of the universe the battle between Dark Matter the force that holds the universe together and dark energy the force seeking to tear it apart has set the universe on a path of destruction if dark matter is the victor the universe might collapse if dark energy rules the cosmos it could rip to shreds the expansion grows so strong that tears up the entire universe it'll be a strange twist of fate dark energy the force that propelled matter to form a magnificent universe continues to push it outward and drives it to its demise to find out if dark energy is in fact winning the battle scientists will first need to know how fast the universe is actually expanding the most remarkable feature of the universe is that it's expanding every galaxy is moving away from every other galaxy when you look out into the night sky you see distant stars galaxies clusters of galaxies they observe with telescopes and they're all moving away from us we can illustrate that with this balloon so we expand it we see that every dot drawn on this black balloon like the night sky is moving away from every other dot but there's something else that we know about the universe something else that we know about the expansion that is that the expansion is getting faster and the universe is accelerating the size of the universe is getting bigger at a faster and faster rate we don't know exactly how fast it's accelerating but if it's accelerating fast enough then something really dramatic could happen the universe could end up tearing itself apart in a big rip this is perfect this is great that you rigged this up so this is this is a giant version of the demo that I do in class dr. Robert Caldwell attempts an Earthbound experiment to show how dark energy affects the acceleration of the universe he uses a paintball gun mounted on a truck yeah and basically I mean we could adjust the angle in any way that you want it what do you think of yeah I think it's down it down a little bit more this is the best that we can mark he sends the truck coasting down an incline Earth's gravity pulls the vehicle downhill which is similar to how dark energy propels the universe outward causing it to expand gravity pulls the truck forward at an increasing speed the gun fires paint at the ground at regular one-second intervals Caldwell measures the distance between the paint dots to calculate just how fast the truck was accelerating he'll use the data from this experiment to see how gravity's force compares to dark Energy's force in the cosmos we started thinking about the big rip when it was discovered that the expansion the universe was accelerating the degree of acceleration is not known and it's the subject of a lot of effort by astronomers today to try and figure out exactly how fast the expansion is growing what is the past evolution of the universe in detail and if we can glean from that what is the future evolution of the universe it's not known exactly how fast its accelerating there's some evidence that the acceleration is beyond a certain threshold and beyond that threshold there's a runaway effect that could take place and it would rip apart the universe fantastic I think we've got some good data great give you that end I'll take this the point of the paintball experiment is to find parallels between the truck propelled by the invisible force of gravity and the accelerating universe I'm glad we got the long tape measure because it's really growing pretty fast the interval within a few measurements the distance between the paint spots increases by nearly seven times if the truck were in space at this rate it would travel faster than 100 miles per hour within a minute and over a thousand miles per hour within 10 minutes they're getting big now forty-two all right 0.5 the question for Robert Caldwell it's whether the same kind of expansion and acceleration are happening on a cosmic scale what's the like the capsule matter is a plastic or some gelatin uh-huh this right here is the data that I took with Eric the cumulative distance travelled by the car as a function of time and that's beautiful it's this nice parabolic shape that's exactly what you expect for an accelerating body now over here I've got another calculation going on where I'm working out the acceleration of the universe Robert Caldwell's calculation shows that forces on earth are similar to forces in space this demonstration then gives a sense of the dramatic rate of expansion that appears to be happening in the cosmos by eye it might be difficult to appreciate how good a fit it is but I can tell you that the weight of the statistics indicates that an accelerating universe is a very good fit to this data if like the truck the universe is continually accelerating then billions of years from now the universe might tear itself apart while the distant stars and galaxies would be pulled away from from each other they'll be pulled away from us but moreover we won't have time to grow cold and lonely it'll actually be pretty exciting and dramatic and violent stars are ripped apart planets are ripped apart even atoms are are torn apart before the universe ends wouldn't happen for at least 50 billion years but still it's an interesting fate for the universe what would Adams ripping apart look like things like coffee cups are solid atoms joined together to create something that will hold a cappuccino without leaking a single drop zoom in through the cup like sailing through the cosmos past the molecules and into the atoms the solid cup is nothing more than a fabric of atomic particles that formed a bond to become matter if these particles were to move apart the bonds that hold this cup together stop working the atoms no longer support molecules the connections between the minuscule particles dissolve matter in the form of this Cup ceases to exist it disintegrates gone from existence this is the dramatic end that Robert Caldwell foresees for the universe what you would see if you were standing on earth or standing on some other planet that happened to still be around at that time you would see something that looks like a wall of darkness approaching you and as the wall of darkness approaches stars would go out galaxies would go out and eventually that wall of darkness would surround the planet and then pretty soon atoms themselves are torn apart and that's it just the wall of darkness shrinks down to a point and that's the end of the universe according to Robert Caldwell that moment is still billions of years off leaving plenty of time to refine the research in a way this is like a detective story we're trying to figure out what is the culprit or who is the culprit responsible for the cosmic acceleration we think we know its name we call it dark energy but we don't know the modus operandi we don't know exactly how it works and what's needed is more information more information about the physics behind the dark energy we want to know exactly what it does and exactly what it's made out of and in answering those questions we'll be able to figure out exactly what is the fate of the universe the big rip is one theory cruising just above Earth's atmosphere and peering deep into space the Hubble telescope provides scientists with clues to a less violent but equally unavoidable end of the universe [Music] scientists now say the universe is expanding and that depending on how fast it is accelerating it might end in a big rip where everything tears apart it's also possible that it will continue to expand but at a slower rate the universe wouldn't rip apart but we become dark cold and lifeless if dark energy turns out to be constant a constant property of space and continues at the same rate that it is now the universe will keep expanding forever and it will be a very sad state I think in the end it just chills out everything cools down evidence for the Big Chill and all of the theories for the end of the universe in part come from the Hubble Space Telescope it has been orbiting earth since 1990 and has an unobstructed view of the cosmos the extraordinary images it beams back to earth are amazing in their clarity and detail and because of Hubble scientists can make better predictions about how the universe will end so here is an example of a very deep field that was taken by the Hubble Space Telescope which literally you point the Space Telescope at a single region in space and if you look at this from a typical ground-based image before Hubble was launched first of all it's a literally almost size of a postage stamp and so suddenly the first Hubble Deep Field that was ever taken had four thousand galaxies that look just like the galaxies here that were never visible before from the ground a tremendous power each of these smudges in their own right is another galaxy each one of these galaxies contains about a hundred billion stars [Music] Hubble sees more than just stars and galaxies it just might be onto one of the key ingredients of space an invisible ingredient that could put the brakes on dark Energy's effect and cause a Big Chill that's dark matter scientists talk about dark matter as the substance that holds the universe together and could prevent a big rip evidence that Dark Matter exists is seen in some of Hubble's images of nearby galaxies it sometimes appears as though other galaxies surround them the other galaxies are not really there at all rather they are reflections of more distant galaxies coming from behind astronomers suspect this optical illusion is dark matter causing a weird distortion of light called gravitational lensing the light from the more distant galaxies is literally bent by the curvature of space caused by stars and dark matter in its path the more dark matter there is between earth and the distant galaxies the more the light will be bent and the greater the force to cause a Big Chill the gravitational lensing is a tremendous tool for the astronomer because we can measure the distortion in background galaxies and use it to trace the distribution of dark matter on various scales we're looking at a distribution of idealized galaxies here on the sky and the light from these distant galaxies is passing through clumps of dark matter what you look at is not really what's happening it's a bit like wearing spectacles and not knowing that you're wearing them if you can tell how much that bending is occurring you can map the dark matter and you can also see well if there's dark matter there is the universe around that dark matter behaving the way it should given the gravity or not if it's slightly gravitating less then dark energy might be changing in those places identifying which energy force dominates dark matter or dark energy will give scientists more confidence about whether a Big Chill or a big rip will be our fate the best evidence shows dark energy as the driving force but by how much solving this mystery depends on astronomers finding ways to measure how fast the universe is moving on earth it's simple to determine how fast something moves an airplane for example is relatively close we can look at it and calculate its speed by estimating the distance it travels and timing how long it takes to get from one point to another but a star's light can travel for millions or billions of years before it can be seen on earth by the time it's light gets here the star will be long gone and it's too far away to gauge its speed or distance traveled with any certainty the universe is expanding only scientists cannot give precise answers about how fast the mystery moves closer to being solved by imaging the cosmos with greater precision [Music] clearer images from space make it easier to estimate the rate of expansion if the universe continues to expand with time then ultimately all of the energy sources the nuclear furnaces and stars would run out and die and the universe would actually get very cold and there'd be something called a Big Chill in the Big Chill scenario earth could become a lonely cold planet as the universe expands distances between stars grow so vast that they nearly disappear from view over time they burn out and eventually the entire universe ends in a frozen state this fear demonstrates the principles behind a Big Chill the marbles coming out of the sphere are like stars that were formed following the Big Bang dark energy propels the Stars outward Dark Matter slows them down in a Big Chill the expansion would continue but the nuclear fuel that causes the stars to burn will eventually run out from Earth's perspective the first thing to go would be sunlight the Sun dims as it exhausts its last bits of nuclear fuel earth would freeze and become lifeless and billions of years after humans are gone the cosmos expands out of view a few newer stars might remain but most would have long moved away the furnace powering the universe burns out the darkened universe continues to expand a frozen and lifeless remnant of its once vibrant existence eventually if this keeps going if nothing changes in the in the composition of this energy density the universe will continue to expand forever it's going to get colder and colder and eventually even the gower neighboring galaxies will be receding from us so fast that we won't be able to see them so the universe is going to get cold and dark and and it will be a very lonely place astronomers have much to learn about the influence of dark energy and dark matter and much of the newest information is coming from this probe in deep space it's sending back information that's helping scientists to interpret the history and the fate of the universe [Music] the night sky by all appearance is a quiet and peaceful place but in reality there are forces that are driving it to an end big science moves astronomers closer to deciphering the universe as great mysteries including its ultimate fate the solution to the universe's riddle may well be hidden in this multi-coloured image what's incredible is that it's a map of the early universe from the moment it was conceived and even more fantastic it reveals a great story that helps cosmologists predict how it will end the machine that captured this is called w map a NASA satellite that's working around the clock to chart the cosmos what we're looking at here is the edge of the visible universe it's the light that W map measured left it's the remnant heat from the Big Bang and this is literally the oldest light in the universe that we can see this fossil relic from the early universe tells us a great deal about what the composition of matter was like what the expansion rate was like and really what the conditions were at the birth of our universe w map is one of the great astronomical breakthroughs of the 21st century nothing before I could give us such a clear image of the energy left over from the Big Bang energy that scientists called a Cosmic Microwave Background w map is measuring temperature differences in the Cosmic Microwave Background which may finally make it possible to predict which force will dominate the universe and how that force will bring the cosmos to its end the blue spots are regions in the microwave light that was produced by the Big Bang that are slightly colder than the average temperature and the red spots are regions that are slightly hotter than the average temperature difference is revealed by W map tell scientists about the nature of the matter and energy that is contained within the universe they're able to analyze the light patterns and find clues not only about the substance but also the fate of the universe we only capture a tiny part of the electromagnetic spectrum with our eyes and we have to go to much longer wavelengths same wavelengths that are used to heat water in a microwave oven or W map is so precise that it can detect differences in temperatures as small as one one thousandth of a degree this sensitivity helps scientists to calculate the ratio of dark matter to dark energy forces that will determine how the universe ends we assembled all those difference measurements and make a map of the variations of like and by turning up the contrast we can can basically subtract off this uniform glow from the Big Bang and look for variation it doesn't look like much until Garry Henshaw just the contrast then the W map image comes to life looking at W map imagery is in essence taking a journey back through space and time so that we might get some new ideas on the fate of the universe pulling away from the probe and following the path of the light it is collecting we past Mars Jupiter and Saturn whose reflected light takes over an hour to reach Earth [Music] then leaving the Milky Way we pass Andromeda the next nearest galaxies whose light takes 2.3 million years to reach us which means we have travelled 2.3 million years back in time [Music] and finally we arrived back 13 billion years ago at the beginning of visible light before that superheated hydrogen gas is everywhere w map can see this far back in history it's confirming important facts about the universe and what's driving it to its demise [Music] the final act for the universe becomes more easily predicted thanks to W map its information combined with the work of astronomers has led to some astounding discoveries concerning a rapidly expanding universe rapid expansion supports the dark energy theory and the possibility of a Big Chill or big rip we now know from all the data we've had in the last 10 years of theirs by a factor of 2 to 1 more dark energy than dark matter so dark energy is the dominant constituent of the energy in the universe the evidence seems clear dark energy is taking over and is leading astronomers into new thoughts about the beginning and the end of the universe before the discovery of dark energy things were a lot simpler if we could determine the amount of matter in the universe then we could say something about its ultimate destiny those simple days are gone but the proof is adding up and supports the idea that the universe will continue to expand but will it do so to oblivion we've made huge strides over the last century and learning something about the evolution of the universe and its expansion but we've now raised more questions in some sense than we've been able to answer and so I think the next decade is going to be even more exciting astronomers have tons and tons of challenges that have been thrown our way by theorists and we are rapidly trying to figure out how to answer all of these questions and I think that's the exciting future because if you if you can go out and really observe something you're testing it and that's what science is all about the battle between dark matter and dark energy is expected to go on for billions of years and humans will be long gone from Earth when the final outcome occurs but no pursuit has been more significant to science than understanding how the universe arrived how it works and how it will end it's a never-ending quest it's driving astronomy what are the answers to these profound questions the constituents of the universe the nature of dark matter and perhaps the biggest mystery of all what is the ultimate fate of the universe [Music] [Music] [Applause] [Music] [Applause] [Music] you [Music] you [Music] [Music] you [Music] [Music] you [Music] you

Channel: How the Universe Works

Views: 137,666

Rating: 4.4679804 out of 5

Keywords: How the Universe Works, Space, Space Discovery Documentary, the universe, space documentary, national geographic, solar system, Big Bang, Black Hole, Dark Matter, Dark Energy

Id: cfIcQyhlBgY

Length: 48min 45sec (2925 seconds)

Published: Fri Jun 28 2019