cientists now realize it's not what hines in the life but what hides in the ark that holds the true secrets of our ky here is a mysterious Dark Matter than ine stars and galaxies together and trange particles like wimps Axion's and acho's might be to blame nd there is a dark repulsive energy is reating space in the universe but riving the galaxies further and further part to a dismal ombined dark matter and dark energy akeup ninety-six percent of the niverse and uncovering their secrets is ike making the one-in-a-million shot if ncovered the ultimate fate of the niverse might be revealed eally crash and burn in a horrific ollision of gravitational forces or real dark energy tear the universe part the betting is the universe will ie in ice nderstanding these two quantities dark atter and dark energy is really undamental to understanding the niverse his is a trip to the dark side of the niverse his is the hunt for dark matter and ark energy ark matter is unlike anything we have ver encountered on earth billions of hese strange particles pass through verything they encounter each second hey are so massive in weight they have he power to influence the galaxies how hey form and how fast they spin Dark atters invisible presence is everywhere r so it seems cience has not directly proven dark atter particles exist there are many uspects but no answers and observing omething you can't see sn't easy that doesn't admit light and t doesn't absorb light it doesn't nteract with light at all ot only does it not shine you can asily see it in obscuration but the vidence is there cience knows it every textbook on the lanet earth says that the universe is ade out of atoms and some subatomic articles well all those textbooks are rong and they are going underground to rove it when they hear about this nvisible matter called dark matter they ay bah humbug show me proof that Dark atter exists udan Minnesota 200 miles from any major ity lights a perfect place for hunting ark matter but not for obvious reasons ou think we'd want to look up in the ky for dark matter that's where dark atter is coming from after all but nstead we're going to Don our helmets nd we're gonna walk down into this mine 431 feet underground is the Sudan ational Laboratory an abandoned iron ine reconfigured into a research acility this is just one lab of many round the world going underground to hield experiments from cosmic rays ach are racing to detect dark matter an nvisible particle that has only been ndirectly observed but never captured e've been at this for now a decade and e have yet to see a dark matter article he hunt for dark matter started almost century ago astronomers finally had he tools to see deep into the night sky nd the questions began so it wasn't ntil the nineteen twenties that the echnology developed well enough so we ould take little fuzzy patches that eople have noticed their telescopes and esolve them and figure out what they re then and when Hubble shocked the orld and declared the universe was igger than just the Milky Way people ealize that some of these little fuzzy atches are separate galaxies just like ur Milky Way galaxy as astronomers iscover new galaxies Caltech professor ritz wiki looked up to the neighboring oma Cluster of galaxies and observed omething strange hen he measured what the motions were n the coma cluster galaxies he got an stimate for how much mass there was in hat custard that he compared it to how uch mass you could actually see by ooking at the galaxies something didn't dd up the galaxies were moving too fast ithin the cluster for the amount of lluminated stuff he could see y his calculations there should have een a hundred sixty times more lluminated mass to account for the andom speeds of galaxies in the cluster omething else was affecting their otions but what was it he analyzed heir motions and concluded that the luster could not be stable unless there as a large amount of dark matter resent in 1933 he was one of the first eople to really grasp the significance f the presence of dark matter he called t missing matter dark matter an nvisible mass it was gravitationally ttractive and was able to affect the peeds of entire galaxies in a cluster evolutionary thinking yes but the iscovery was largely ignored think that people took this wiki eriously but they didn't jump to any onclusions this is a time when the niverse was just beginning to be xplored it was the nineteen twenties hen we first realized there were alaxies outside our own but we didn't now back then was whether it was simply alaxies or stars or gas or dust that we ouldn't see where weather is something ruly different Ricky's observations ere based on measuring the mass in the tars and galaxies but how do you weigh tuff in space an't go and put the Sun on a scale ittle bit harder but what you can do is ou can measure how fast the planets are oving around the Sun and the more stuff here is in the Sun the faster those lanets have to move to stay in their rbits Newton and Einstein both said the ore mass or stuff you have an object he more gravitational pull it will have nd the further an object is from the enter the slower it should travel in rbit because the gravitational Paul is eaker according to Einstein's general heory of relativity or even according o Newtonian gravity all of the galaxies re pulling on each other it's like the un's influence on our solar system the ass of the Sun pulls mercury faster han Pluto because mercury is positioned loser to the Sun ikewise for galaxy expect that you got urther and further away hings are moving more and more slowly o stay in their orbits but Zwicky idn't observe that neither did a young cientist named Vera Rubin 50 years ater she was observing the rotational urves of galaxies similar to the Milky ay likes wiki her observations also eems strange but very Reuben actually easured with a to get further and urther away the velocity of the rbiting gas-industrial remained onstant what Rubin observed was as if a ity where galaxies and every car on the oad was a planet or star and despite he amount of traffic every car traveled round the city at the same speed this ame consistent rotational speed espite the amount of stuff or traffic as exactly what Rubin observed he outer parts of the galaxy were otating fast enough that there must be lot more mass otherwise the Galaxy ould have flown apart the only way to esolve this paradox of galaxies which pin 10 times too fast is to assume that here is a halo a halo of invisible atter surrounding the galaxy keeping he Galaxy whole dark matter was present n the galaxies and it had enough mass o keep the rotation speed constant magine that I'm the darknet this ball s a star orbiting me because my ravitational force is keeping it in lace but even if you couldn't see me ou would know that there must be omething here otherwise the star will esume off in a straight line there must e something causing that gravity and hat's how we know there must be dark atter move an estimated that there was 0 times more dark matter than ordinary lluminated stuff ince then we've analyzed hundreds of alaxies and they all have the same attern they all wrote a too fast for heir own good and they need dark matter o hold them together this time science aid attention and started to wonder hat is dark matter how do you find omething that is invisible in space hey needed to see just where dark atter was hiding out in the universe nd even if they couldn't see it cience realized that Dark Matter xposed itself by bending light that asses through it it's called gravitational lensing and it's a virtual spotlight that uncovers any invisible stuff in the universe what it does do is it does what all matters and that it can deflect the library so Ally right can be reflected in its path by da Matta by tracing the battered lights path gravitational lensing detected Dark Matter concentrated in the Halos of galaxies gravitational lensing proved to be infallible and Dark Matters presence was suddenly revealed this technique of gravitational lensing is the most precise because we can actually pinpoint not just how much dark matter there is but how its distributed in its position on the sky and that's because we can measure the distortion of the light rays passing through the dark matter how do you know that your glasses are there because it bends light in the same way by looking at Hubble Space pictures of the universe and looking at the distortion of light as it goes through galaxies we actually have maps of dark matter most of the mass of the galaxy is from the Dark Matter the ordinary matter accumulates in the gravitational field of the dark matter but once dark matter came on the scene scientists wondered if it was a new undetected particle or just invisible ordinary matter when people found don't matter everybody wanted to know what is it you know and of course the first answer is it's just the stuff that makes up you and me but it's not shining scientists started to investigate objects in the universe that didn't emit light black holes were considered they don't emit light can draw matter to themselves and are detected with gravitational lensing it could take the form of black holes or nachos massive compact halo objects which are basically dark small stars that don't give off a lot of light macho's hide out in the halo of the Milky Way and are detected by gravitational lensing but there weren't enough to account for the amount of dark matter needed failed stars like brown dwarfs were also suspected they are massive enough to make up Dark Matters presence whatever dark matter is there is way more of it than the ordinary matter of stars and planets 10 times more all the stuff that you can construct from ordinary atoms protons and neutrons and electrons cannot possibly be enough to account for the total amount of matter that you see in galaxies and clusters scientists continue to present new suspects as the search continued for dark matter previously discovered exotic particles like neutrinos were reconsidered like dark matter neutrinos are passing through the earth millions of particles at a time that they are too light to account for Dark Matters effect on gravity and scientists can recreate neutrinos in particle colliders they also come the Sun Axion's is also another possible Dark Matter candidate they were invented to explain a particular glitch in one of the particle physics theories they would be extremely light so you search for them in a completely different way than what we're doing but there would be there would also be very numerous and so they could possibly be the dark matter Axion's are very light and are believed to have been created at the moment of the Big Bang just like dark matter the theories suggest that they could change to protons while dark matter is stable after exhausting all the usual suspects many scientists believe dark matter is a new exotic particle unlike anything on earth and billions are passing through us every second up until the discovery of dark matter scientists believe the universe was made only of protons neutrons and electrons the stuff everything on earth is made of and we know it has some mass we left with something that we've not yet detective but to be a perfect Dark Matter candidate it must have certain physical properties and none of the usual suspects were fitting the crime so we know the dark matter is some ponderous substance you know that it's not moving too quickly and we know that we can't see it don't matter particles are not traveling at the speed of light and they don't interact with you and me or anything pretty well that's why it's been so difficult to track down these particles and it doesn't interact with ordinary matter except through gravity if I had some dark matter in my hand it would have weight but first it would dissolve right through my fingers there aren't any candidates for cold dark matter within will be called the Standard Model of particle physics like an invisible man passing through walls dark matter is passing through earth billions of particles at a time never colliding with ordinary matter so the most popular idea for what the dark matter could be something called a win wimps are weakly interacting massive particles they have not been detected but their characteristics match the perfect Dark Matter candidate at the Soudan laboratory the Fermilab team has gone underground braving thousands of bats to try and capture a wimp article this is called the cryogenic Dark Matter search CDMS is the acronym for this was a an iron ore mine until nineteen sixty-two when it shut down where half mile underground Fermilab has designed a machine that sub-zero temperatures can detect a dark matter particle passing through it and its sensor is made of germanium a dense metal jam-packed with atoms it's a very pure block of germanium it's got on the surface of it a pattern of tiny little thermometers basically that are able to detect when a particle passes through this hockey-puck sized chunk of germanium dark matter is streaming right through us right now without doing anything very occasionally it will bump into the nucleus of an atom and that's the signature that we're hoping to see to get a clean Dark Matter hit Fermilab needed to filter out junk from space we would get so many particles that it would it would be really trying to assist the needle in a haystack from a lab experiment picks up all matter that passes through this detector the less junk in the air the easier it will be to detect a dark matter particle because dark matter doesn't interact easily with regular protons and electrons from the lab has frozen the germanium pucks to near sub-zero temperatures if a dark matter particle comes through and hits a nucleus it will actually change the temperature of the crystal very slightly and so we're looking for that tiny change of temperature in the crystal to signal that a dark matter particle has passed by sixteen germanium pucks sit in a chamber inside a clean room so we're suited up we're about to go into the experimental room its class 10,000 clean room that's why we're all suited up so we don't carry any dust because that would cause background for the experiment so let's go inside so we have ventilation counters that are catching any cosmic ray particles to get all the way down underground here go right here is what keeps our experiment hold that tiny little bit above absolute zero this is a dilution refrigerator way inside here are you selected detectors so we're just waiting for well dark matter particle to get down to the step and get one of those thinkers told the very way Fermilab has been visiting the mine for nearly two years trying to capture dark matter this is far harder than it sounds although billions of particles are passing through earth at one time it's a one-in-a-million shot dark matter will interact with ordinary matter getting a dark matter particle to hit a germanium atom is like an archer trying to hit a bull's-eye the target is a mile away all these green lights indicate particles passing through the germanium and silicon detectors that we saw downstairs these are almost certainly all background particles but maybe it's buried in there someplace as a whim but we won't know until we analyze the data hunting dark matter is tedious each day the Fermilab team reports to the underground lab analyzes data and perfects their ping-pong game while waiting for the one hit that will prove Dark Matter exists but for all this effort and waiting around no dark matter has been detected by Fermilab or by anyone else unfortunately we've seen precisely zero dark matter particles so far any day now we may have the announcement that businesses have captured dark matter in a bottle we have a hypothesis it certainly seems to explain the universe we live in but the plain fact is we haven't yet detective this cold dark matter particle finding dark matter will not only give us proof of its existence but might also answer the other big questions of space detecting Dark Matter directly will give us a window and what was going on one-ten thousandth of a second after the Big Bend if scientists can discover what dark matter is they might also discover how the universe behaved in its life dark matter is not only a mysterious quality in the universe but also its fundamental to our you know why we're here in fact it will be difficult to form galaxies and hence you know the solar system and hands life on Earth the story of dark matter and dark energy can't be told without going back to the beginning of time to the moment of the Big Bang with space didn't exist there is no Center where you can point to and that's exactly the analogy for the Big Bang there is no direction in the sky from which all the galaxies are expanding from this moment of nothing to a violent explosion space was created and the universe began to grow from seed particles for in a nuclear fusion gas and energy ordinary matter was reacting with other ordinary matter the early universe was in fact a nuclear reactor when it was one minute all and 380,000 years later bits of particles began to cluster creating the seeds from which stars and galaxies would later form big lumps growth form yet bigger lumps and so gravity is slowly pulling force of the bringing objects together what scientists now realize was that at the moment of the Big Day dark matter was created and it played a critical role in helping ordinary matter clump together to form stars and planets like steel girders used on a building site Dark Matters slow-moving particles acted like scaffolding upon which ordinary matter could attach itself we believe that because it's cold and doesn't interact very much that dark matter was pulled together by gravity very slowly over time and actually formed the seeds around which normal matter coalesced into galaxies like a cosmic web like a spider's web where there are strands of da Matta and where these strands intersect like a scaffolding patent in a sense the dark matter is the framework it's providing the scaffolding for the shining galaxies that we can easily see you are really like the Christmas tree lights they're not the actual christmas things that are visible from very very far away but the reality of the galaxy is a big halo most of which you don't see you see the shiny bits that are stars and planets that have accumulated the center of that large halo which is mostly dark matter scientists have long wondered where galaxies formed in seemingly random patterns across space now scientists know it's because of Dark Matters gravitational pull the universe is not uniform at all but has voids it has clumps he seems to have bubble-like regions but we're not believe is due to dark matter in the last year astronomers have been able to take their theory one step further and create a detailed 3d map of dark matter in the universe using gravitational lensing an Einstein said the gravity effects everything just like gravity is caused by everything so one of the things that is affected by gravity is life itself because when light goes to dark matter it bends just the way light bends when it goes to class and light doesn't discriminate between ordinary matter and dark both types of matter matter lights path as it travels through galaxies like plotting a course on a map astronomers have traced thousands of light sources as they pass through dark matter it is given science the most accurate picture yet where dark matter hides in space we can compare that map of the dark matter with where the galaxies are and lo and behold we find that the dark matter is acting as the skeleton it is the backbone around which the visible material is clumping by napping the universe astronomers can also look back in time and predict how much matter was created at the big bag so if you know how lumpy the universe appears now and when it was half its current size when it's half its current size before that you've been inferred to stop the universe it gives us another very nice way of matching on to what we believe the total amount of dark matter it's estimated dark matter makes up twenty-three percent of the universe while ordinary matter makes up only four percent you need a lot of dark matter to account for the total amount of gravity that exists in these clusters and galaxies but what makes up the final seventy-three percent of the universe scientists were shocked to discover a new mysterious dark energy was dominating space and it's repulsive energy is driving the galaxies apart science always assumed that although the universe continues to grow in size it would eventually slow in its expansion or perhaps even collapse on itself gravity would overcome any momentum it had but while measuring the expansion history of the universe scientists were shocked to realize that the universe wasn't slowing down it was speeding up and a grim fate awaited any living thing the universe will disintegrate and temperatures will become so cold that any intelligent life will freeze to death from the moment the Big Bang created the universe space has been expanding and never stopping carrying galaxies along for the ride the space in between the galaxies is expanding the galaxies are not expanding the earth is not expanding the solar system is not expanding it would hobble first discovered galaxies were moving away from the Milky Way in 1929 by realizing the more distant galaxies move faster away from us than the nearby ones he realized he could measure their velocities by studying their wavelengths through a prism it's called measuring the redshift and is still used to measure distances in space and he found that in fact the greater the distance of a galaxy right now the greater the speed with which it's moving away from us that is the greater its redshift a few years ago astronomers decided to use redshift measurements to measure the expansion history of the universe but how do you measure the entire expansion history of the universe how do you travel back 12 billion years in time we have the capability of going back in time directly to observe the past so much in the same way as a geologist you know looks at layers in the Grand Canyon as it goes down in the lower and lower layers looking back in in history if you look at progressively more distant galaxies you're looking at them as they were progressively greater times in the past to measure expansion history scientists used type 1a supernovas as their standard candle one example of a standard candle might be a 100-watt light ball you could have a bunch of these things sitting around in your room at different distances from you then the more distant ones will appear fainter and more nearby ones will appear brighter type 1a supernovas are always consistently brilliant no matter where they occur in space a supernova is the colossal explosion of a star at the end of its life it just goes come back and it occurs when a dying star known as a white dwarf goes through a nuclear runaway and just literally blows itself to smithereens we find the type 1a supernovae in very distant galaxies so they look really faint and they then we compare them with type 1a supernovae in nearby galaxies whose distance work distances were measured using Cepheid variables or some other technique using these type 1a supernovas two different teams set out in the nineteen nineties to measure the deceleration rate of the universe but to capture supernovas as they occur astronomers had to put the universe on surveillance you can compare this a little bit too perhaps surveying a casino so all these cameras are on all the time and most the time they don't find much of anything interesting but occasionally they find what they're looking for you have to look at lots of galaxies so what we did is we took large telescopes with cameras that have wide fields of you about as wide to save with of the full moon and we took many snapshots of space using this widefield camera and each each snapshot contains tens of thousands of galaxies and by comparing the apparent brightness of the distant light one days with those of the nearby 51 days in nearby galaxies we can get the distance of the distant galaxies and hence the amount of time that we're looking back in the history of the universe after the two teams studied the results of 60 type 1a supernovas scientists were shocked at their results the universe wasn't slowing down its expansion was speeding up we all expected that expansion to be slowing down with time because after all all of the galaxies are pulling on one another we were so confident we were going to measure the rate at which the universe was slowing down and then we found of course a negative answer the universe is not slowing down it's speeding up and this was just a big mystery that is really really weird you know we expected to measure some amount of slow down and instead it's expanding more quickly that's like the wrong sign right we were really afraid that we had gotten completely the wrong answer we rechecked our measurements we checked the analysis a bunch of people on each of the two teams that the measurements and the analysis independently and kept getting getting the same result one of the greatest shocks in the world of cosmology just in the last few years has been the realization that our universe is accelerating this repulsive force driving the universe was called dark energy and invisible energy that was nothing anyone expected or understood it suggests that over the largest distances in the universe there's a repulsive effect that dominates over gravity and dark energy is creating space taking galaxies along for the ride this energy that appears to fill the universe and stretch the expansion of the universe faster and faster with time is now known as as dark energy so here I throw the Apple and initially its decelerating and then dark energy makes it accelerate away from me so you throw the Apple and it just zooms away faster and faster with time like the Apple forever traveling into space galaxies are being carried away as more space is created so if you could imagine you know a classroom populated by chairs and those chairs are slowly getting further apart from one another within a classroom because of all the chairs are being stretched apart like an expanding universe no matter which chair you sit up you'll find all chairs are moving away from you so the chairs are not really expanding about a chance of the same size really what's happening is that the room is getting bigger office space in between the chest is being stretched apart more space is being created in between the galaxies you have individual galaxies remaining of constant size in a universe where all of space is getting bigger and bigger dark energy is very different from dark matter it doesn't clump up like galaxies do in clusters are like stars do in galaxies instead it appears to be pretty uniform and we find the same amount of acceleration no matter which direction we look at its probably smooth although some people believe that maybe structure and its distribution and its influence dark energy is the energy of the vacuum the energy of nothing evening nothingness has energy and it's pushing the galaxies apart creating a runaway universe it appears dark energy and Dark Matter have been at war with one another since the beginning of time science believes dark energy was created along with dark matter at the moment of the Big Bang it has always existed in the universe the gravitational forces of dark matter kept in check slowing down the expansion of space during the first nine billion years of time this changed five billion years ago when the universe grew big enough so that dark matter was dispersed throughout the universe and dark energy wasn't so affected by Dark Matters pole as a result the universe began to expand at an accelerated rate dark energy is a constant tub that was probably very insignificant when the universe was hot and dense in the beginning so it doesn't really matter where the dark energies there or not it is there evidence that just plays no role at all and then as the universe gets cooler and less dense bigger so gravity lesson for and then dark energy takes over it's a property of space that we don't yet fully understand as the universe expanded astronomers realized dark energy won its struggle with dark matter and started the acceleration five billion years ago so there came a time about five billion years ago when the dark energy started dominating over the attractive matter in the universe in a sense if you plotted force versus time the gravitational attraction is declining with time the repulsion is increasing with time and about five billion years ago the two curves crossed and that's when the universe started accelerating in its expansion dark energy is fundamental to understand because it's houses where the universe is going what's the fate of the universe to expand forever and get cold and dark or is that you know some and insight dark energy now drives the expansion of the universe and it doesn't seem to be stopping the repulsive effect of the dark energy increased because the more space there is between galaxies the greater is the cumulative effect of the dark energy the repulsive effect an individual galaxies seem destined to alone the existence so it looks as if this is the end of everything surprisingly the theory of dark energy was proposed and discarded long ago from one of physics greatest minds he called it his biggest blunder his name was Einstein and he might have been onto the greatest discovery of the 21st century 80 years before anyone had a clue science now understands that dark energy is creating and expanding space but in the early 20th century astronomers believed the universe was only as big as the Milky Way and would never grow in size but Einstein had just formed his theory of relativity and decided to test it on the static universe but as hard as hein Stein tried he could not balance his equation to equal a static universe his calculations showed a universe that must either expand or contract you realize that if you had a universe that was smooth it was uniformly distributed with stuff his theory unambiguously predicted that it should either be expanding or contracting so Einstein proposed a repulsive vacuum energy that would hold the universe in balance with attractive gravity he called it his cosmological constant a constant energy it would hold the universe in balance introduced the cosmological constant or dark energy to hold the universe static when Hubble announced space was expanding suddenly Einsteins cosmological constant seemed irrelevant and he labeled it his biggest blunder now it turns out that dark energy the concept that he threw away back to the nineteen-twenties is in fact the dominant force blowing the universe apart Einstein's so-called blunder will eventually determine whether or not the universe guys and fire or ice and the betting is the universe will die in nice in trying to survey how the universe behaves Einstein had erroneously predicted dark energy and what is the total makeup of the universe the total amount of stuff in ordinary matter and dark matter is not enough to a talent for the curvature of space the winter like looking across the horizon on earth the size of the universe is so great the curvature of space appears flat to add ordinary matter dark matter and dark energy together that makes a prediction for the curvature of space that prediction comes spot-on you get the right answer our satellite data now has revealed the fact that seventy-three percent of the matter-energy content of the universe is dark energy and dark energy which was once Einsteins blunder is now known to be the dominant force in the universe his blunders are our great discovery scientists are at the very beginning of understanding what effect dark energy will have on the fate of the universe ideally we'd like to measure how dark energy is behaving as the universe ages eventually when the dark energy completely dominates over dark matter the universal interest stage known as exponential expansion for every given unit of time it'll double in size and unless the dark energy changes sign sunday and becomes gravitationally attractive the fate of the universe is to expand forever more and more quickly with time we don't understand if the vacuum energy is driving the acceleration of the universe why it has the amount of Dunn's that is one of the deepest puzzles remaining theoretical physics today trillions of years from now it's going to be a very lonely place will look up in the sky and the skies will be practically dark the oceans will freeze over and it looks as if this is the death of all intelligent life it looks as if dark energy and the laws of physics are a death warrant to all intelligent life in the universe in discovering dark matter and dark energy science is one step closer to defining the theory of everything one equation that will define the entire workings of the universe once we have the theory of everything will be able to answer some of the deepest questions ever since man and women first look at the heavens this could be the crowning achievement of 2,000 years of investigation into the laws of nature ever since the Greeks ask the question what are things made for now dark matter and dark energy continue to be the greatest cosmological questions of the 21st century it's really frustrating yes I mean it's humbling to to know that you know all we know about physics is restricted the normal matter and yet there's all this other dark matter and dark energy that we really understand very little about it's the beginning of a new era and the mysteries of the dark side of the universe it's the Wild West as far as particle astrophysics which is what we call this field it's a property of space that we don't get fully understand for thousands of years we have looked at the night sky and believed that the illuminated stuff was all that made up our universe scientists now realize it's not what shines in the life but what hides in the dark that holds the true secrets of our sky there is a mysterious dark matter that binds stars and galaxies together and strange particles like wimps Axion's and macho's might be to blame and there is a dark repulsive energy that is creating space in the universe but driving the galaxies further and further apart to a dismal fate combined dark matter and dark energy makeup ninety-six percent of the universe and uncovering their secrets is like making the one-in-a-million shot if uncovered the ultimate fate of the universe might be revealed really crash and burn in a horrific collision of gravitational forces for you know dark energy tear the universe apart the betting is the universe will die in ice understanding these two quantities dark matter and dark energy is really fundamental to understanding the universe this is a trip to the dark side of the universe this is the hunt for dark matter and dark energy dark matter is unlike anything we have ever encountered on earth billions of these strange particles pass through everything they encounter each second they are so massive in weight they have the power to influence the galaxies how they form and how fast they spin Dark Matters invisible presence is everywhere or so it seems science has not directly proven dark matter particles exist there are many suspects but no answers and observing something you can't see isn't easy that doesn't admit light and it doesn't absorb light it doesn't interact with light at all not only does it not shine you can easily see it in obscuration but the evidence is there science knows it every textbook on the planet earth says that the universe is made out of atoms and some subatomic particles well all those textbooks are wrong and they are going underground to prove it when they hear about this invisible matter called dark matter they say bah humbug show me proof that Dark Matter exists sudan Minnesota 200 miles from any major city lights a perfect place for hunting dark matter but not for obvious reasons so you think we'd want to look up in the sky for dark matter that's where dark matter is coming from after all but instead we're going to Don our helmets and we're gonna walk down into this mine 2431 feet underground is the Sudan National Laboratory an abandoned iron mine reconfigured into a research facility this is just one lab of many around the world going underground to shield experiments from cosmic rays each are racing to detect dark matter an invisible particle that has only been indirectly observed but never captured we've been at this for now a decade and we have yet to see a dark matter particle the hunt for dark matter started almost a century ago astronomers finally had the tools to see deep into the night sky and the questions began so was until the nineteen twenties that the technology developed well enough so we could take little fuzzy patches that people have noticed their telescopes and resolve them and figure out what they are then and when Hubble shocked the world and declared the universe was bigger than just the Milky Way people realize that some of these little fuzzy patches are separate galaxies just like our Milky Way galaxy as astronomers discover new galaxies Caltech professor Fritz wiki looked up to the neighboring Coma Cluster of galaxies and observed something strange when he measured what the motions were in the coma cluster of galaxies he got an estimate for how much mass there was in that customer that he compared it to how much mass you could actually see by looking at the galaxies something didn't add up the galaxies were moving too fast within the cluster for the amount of illuminated stuff he could see by his calculations there should have been a hundred sixty times more illuminated mass to account for the random speeds of galaxies in the cluster something else was affecting their motions but what was it he analyzed their motions and concluded that the cluster could not be stable unless there was a large amount of dark matter present in 1933 he was one of the first people to really grasp the significance of the presence of dark matter he called it missing matter an invisible mass that was gravitationally attractive and was able to affect the speeds of entire galaxies in a cluster revolutionary thinking yes but the discovery was largely ignored I think the people took this wiki seriously but they didn't jump to any conclusions this is a time when the universe was just beginning to be explored it was the nineteen twenties when we first realized there were galaxies outside our own but we didn't know back then was whether it was simply galaxies or stars or gas or dust that we couldn't see where weather is something truly different wiki's observations were based on measuring the mass in the stars and galaxies but how do you weigh stuff in space can't go and put the Sun on a scale it's a little bit hard but what you can do is you can measure how fast the planets are moving around the Sun and the more stuff there is in the Sun the faster those planets have to move to stay in their orbits Newton and Einstein both said the more mass or stuff you have an object the more gravitational pull it will have and the further an object is from the center the slower it should travel in orbit because the gravitational pull is weaker according to Einstein's general theory of relativity or even according to Newtonian gravity all of the galaxies are pulling on each other it's like the sun's influence on our solar system the mass of the Sun pulls mercury faster than Pluto because mercury is positioned closer to the Sun likewise for Galaxy would expect as you got further and further away things are moving more and more slowly to stay in their orbits but Ricky didn't observe that neither did a young scientist named Vera Rubin 50 years later she was observing the rotational curves of galaxies similar to the Milky Way likes wiki her observations also seem strange but very Reuben actually measured with a to get further and further away the velocity of the orbiting gas-industrial named constant what Rubin observed was as if a city where galaxies and every car on the road was a planet or star and despite the amount of traffic every car traveled around the city at the same speed this same consistent rotational speed despite the amount of stuff or traffic was exactly what Rubin observed the outer parts of the galaxy were rotating fast enough that there must be a lot more mass otherwise the Galaxy would have flown apart the only way to resolve this paradox of galaxies which spin 10 times too fast is to assume that there is a halo a halo of invisible matter surrounding the galaxy keeping the Galaxy whole dark matter was present in the galaxies and it had enough mass to keep the rotation speed constant imagine that I'm the dark matter this ball is a star orbiting me because my gravitational force is keeping it in place but even if you couldn't see me you would know that there must be something here otherwise the star will resume off in a straight line there must be something causing that gravity and that's how we know there must be dark matter move an estimated that there was 10 times more dark matter than ordinary illuminated stuff since then we've analyzed hundreds of galaxies and they all have the same pattern they all rotate too fast for their own good and they need dark matter to hold them together this time science paid attention and started to wonder what is dark matter how do you find something that is invisible in space they needed to see just where dark matter was hiding out in the universe and even if they couldn't see it science realized that Dark Matter exposed itself by bending light that passes through it it's called gravitational lensing and it's a virtual spotlight that uncovers any invisible stuff in the universe what it does do is it does what all matters and that it can deflect the light rain so Ally rate can be deflected in its path by dark matter by tracing the battered lights path gravitational lensing detected Dark Matter concentrated in the Halos of galaxies gravitational lensing proved to be infallible and Dark Matters presence was suddenly revealed this technique of gravitational lensing is the most precise because we can actually pinpoint not just how much dark matter there is but how its distributed in its position on the sky and that's because we can measure the distortion of the light rays passing through the dark matter how do you know that your glasses are there because it bends light in the same way by looking at Hubble Space pictures of the universe and looking at the distortion of light as it goes through galaxies we actually have maps of dark matter most of the mass of the galaxy is from the Dark Matter the ordinary matter accumulates in the gravitational field of the dark matter but once dark matter came on the scene scientists wondered if it was a new undetected particle or just invisible ordinary matter when people found don't matter everybody wanted to know what is it you know and of course the first answer is it's just the stuff that makes up you and me but it's not shining scientists started to investigate objects in the universe that didn't admit light black holes were considered they don't emit light can draw matter to themselves and are detected with gravitational lensing could take the form of black holes or nachos massive compact halo objects which are basically dark small stars that don't give off a lot of light macho's hide out in the halo of the Milky Way and are detected by gravitational lensing but there weren't enough to account for the amount of dark matter needed failed stars like brown dwarfs were also suspected they are massive enough to make up Dark Matters presence whatever dark matter is there is way more of it than the ordinary matter of stars and planets 10 times more all the stuff that you can construct from ordinary atoms protons and neutrons and electrons cannot possibly be enough to account for the total amount of matter that you see in galaxies and clusters scientists continue to present new suspects as the search continued for dark matter previously discovered exotic particles like neutrinos were reconsidered like dark matter neutrinos are passing through the earth millions of particles at a time but they are too light to account for Dark Matters effect on gravity and scientists can recreate neutrinos in particle colliders they also come the Sun Axion's is also another possible Dark Matter candidate that they were invented to explain a particular glitch in one of the particle physics theories they would be extremely light so you search for them in a completely different way than what we're doing but there would be there would also be very numerous and so they could possibly be the dark matter axion Tsar very light and are believed to have been created at the moment of the Big Bang just like dark matter but theories suggest that they could change to protons while dark matter is stable after exhausting all the usual suspects many scientists believe dark matter is a new exotic particle unlike anything on earth and billions are passing through us every second up until the discovery of dark matter scientists believe the universe was made only of protons neutrons and electrons the stuff everything on earth is made of and we know it has some mass and we left with something that we've not yet detected but to be a perfect Dark Matter candidate it must have certain physical properties and none of the usual suspects were fitting the crime so we know the dark matter is some ponderous substance you know that it's not moving too quickly and we know that we can't see it that matter particles are not traveling at the speed of light and they don't interact with you and me or anything pretty well that's why it's been so difficult to track down these particles and it doesn't interact with ordinary matter except through gravity if I had some dark matter in my hand it would have weight but first it would this all right through my fingers there aren't any candidates for cold dark matter with it will be called the Standard Model of particle physics like an invisible man passing through walls dark matter is passing through earth billions of particles at a time never colliding with ordinary matter so the most popular idea for what the dark matter could be something called a win wimps are weakly interacting massive particles they have not been detected but their characteristics match the perfect Dark Matter candidate at the Soudan laboratory the Fermilab team has gone underground braving thousands of bats to try and capture a wimp article this is called the cryogenic Dark Matter search CDMS is the acronym for this was a an iron ore mine until nineteen sixty-two when it shut down where half mile underground from a lab has designed a machine that sub-zero temperatures can detect a dark matter particle passing through it and its sensor is made of germanium a dense metal jam-packed with atoms it's a very pure block of germanium it's got on the surface of it a pattern of tiny little thermometers basically that are able to detect when a particle passes through this hockey-puck sized chunk of germanium dark matter is streaming right through us right now without doing anything very occasionally it will bump into the nucleus of an atom and that's the signature that we are hoping to see to get a clean Dark Matter hit Fermilab needed to filter out junk from space we would get so many particles that it would it would be really trying to assist the needle in a haystack from a lab experiment picks up all matter that passes through this detector the less junk in the air the easier it will be to detect a dark matter particle because dark matter doesn't interact easily with regular protons and electrons from a lab has frozen the germanium pucks to near sub-zero temperatures if the dark matter particle comes through and hits a nucleus it will actually change the temperature of the crystal very slightly and so we're looking for that tiny change of temperature in the crystal to signal that a dark matter particle has passed by sixteen germanium pucks sit in a chamber inside a clean room so we're suited up we're about to go into the experimental room its class 10,000 clean room that's why we're all suited up so we don't carry any dust because that would cause background for the experiment so let's go inside so we have scintillation counters that are catching any cosmic ray particles to get all the way down underground here so right here is what keeps our experiment hold that tiny little bit above absolute zero this is a dilution refrigerator way inside here are the remaining selected detectors so we're just waiting for wealth dark matter particle to get step one of those crystal fairy wait Fermilab has been visiting the mine for nearly two years trying to capture dark matter this is far harder than it sounds although billions of particles are passing through earth at one time it's a one-in-a-million shot dark matter will interact with ordinary matter getting a dark matter particle to hit a germanium atom is like an archer trying to hit a bull's-eye when the target is a mile away all these green lights indicate particles passing through the germanium and silicon detectors that we saw downstairs these are almost certainly all background particles but maybe it's buried in there someplace as a whim but we won't know until we analyze the data hunting dark matter is tedious each day the Fermilab team reports to the underground lab analyzes data and perfects their ping-pong game while waiting for the one hit that will prove Dark Matter exists but for all this effort and waiting around no dark matter has been detected by Fermilab or by anyone else unfortunately we've seen precisely zero dark matter particles so far any day now we may have the announcement that businesses have captured dark matter in a bottle we have a hypothesis it certainly seems to explain the universe we live in but the plain fact is we haven't yet detective this cold dark matter particle finding dark matter will not only give us proof of its existence but might also answer the other big questions of space detecting Dark Matter directly will give us a window onto what was going on one-ten thousandth of a second after the Big Bend if scientists can discover what dark matter is they might also discover how the universe behaved early in its life dark matter is not only a mysterious quality in the universe but also its fundamental to our you know why we're here in fact it will be difficult to form galaxies and hence you know the solar system and has life on Earth the story of dark matter and dark energy can't be told without going back to the beginning of time to the moment of the Big Bang when space didn't exist there is no Center where you can point to and that's exactly the analogy for the Big Bang there is no direction in the sky from which all the galaxies are expanding from this moment of nothing to a violent explosion space was created the universe began to grow from a seed particles for in a nuclear fusion of gas and energy ordinary matter was reacting with other ordinary matter the early universe was in fact a nuclear reactor when it was one minute old and 380,000 years later bits of particles began to cluster creating the seeds from which stars and galaxies would later form big lumps growth form yet bigger lumps and so gravity is slowly pulling force of the bringing objects together what scientists now realize was that at the moment of the Big Day dark matter was created it played a critical role in helping ordinary matter clump together to form stars and planets like steel girders used on a building site Dark Matters slow-moving particles acted like scaffolding upon which ordinary matter could attach itself we believe that because it's cold and doesn't interact very much that dark matter was pulled together by gravity very slowly over time and actually formed the seeds around which normal matter coalesced into galaxies like a cosmic web like a spider's web where there are strands of da Matta and where these strands into sacked like a scaffolding pattern in a sense the dark matter is the framework it's providing the scaffolding for the shining galaxies that we can easily see you are really like the Christmas tree lights they're not the actual christmas the things that are visible from very very far away but the reality of the galaxy is a big halo most of which you don't see you see the shiny bits that are stars and planets that have accumulated the center of that large halo which is mostly dark matter scientists have long wondered why galaxies formed in seemingly random patterns across space now scientists know it's because of Dark Matters gravitational pull the universe is not uniform at all but has voids it has clumps he seems to have bubble-like regions what we not believe is due to dark matter in the last year astronomers have been able to take their theory one step further and create a detailed 3d map of dark matter in the universe using gravitational lensing an Einstein said the gravity effects everything just like gravity is caused by everything so one of the things is affected by gravity is life itself because when light goes to dark matter it bends just the way light bends when it goes to class and light doesn't discriminate between ordinary matter and dark both types of matter matter lights path as it travels through galaxies like plotting a course on a map astronomers have traced thousands of light sources as they pass through dark matter it is given science the most accurate picture yet where dark matter hides in space we can compare that map of the dark matter with where the galaxies are i lo and behold we find that the dark matter is acting as the skeleton it is the backbone around which the visible material is clumping by mapping the universe astronomers can also look back in time and predict how much matter was created at the big bag if you know how lucky the universe appears now and when it was happens current size whether it's happens current size before that you've been inferred to stop the universe it gives us another very nice way of matching on to what we believe the total amount of dark matter it's estimated dark matter makes up twenty-three percent of the universe while ordinary matter makes up only four percent need a lot of dark matter to account for the total amount of brandy that exists in these clusters and galaxies but what makes up the final seventy-three percent of the universe scientists were shocked to discover a new mysterious dark energy was dominating space and it's repulsive energy is driving the galaxies apart science always assumed that although the universe continues to grow in size it would eventually slow in its expansion or perhaps even collapse on itself gravity would overcome any momentum it had but while measuring the expansion history of the universe scientists were shocked to realize that the universe wasn't slowing down it was speeding up and a grim fate awaited any living thing the universe will disintegrate and temperatures will become so cold that any intelligent life will freeze to death from the moment the Big Bang created the universe space has been expanding and never stopping carrying galaxies along for the ride the space in between the galaxies is expanding the galaxies are not expanding the earth is not expanding the solar system is not expanding it would hobble first discovered galaxies were moving away from the Milky Way in 1929 by realizing the more distant galaxies move faster away from us than the nearby ones realized he could measure their velocities by studying their wavelengths through a prism it's called measuring the redshift and is still used to measure distances in space and he found that in fact the greater the distance of a galaxy right now the greater the speed with which it's moving away from us that is the greater its redshift a few years ago astronomers decided to use redshift measurements to measure the expansion history of the universe but how do you measure the entire expansion history of the universe how do you travel back 12 billion years in time we have the capability of going back in time directly to observe the past so much in the same way as a geologist you know looks at layers in the Grand Canyon and as it goes down in the lower and lower layers looking back in in history if you look at progressively more distant galaxies you're looking at them as they were progressively greater times in the past to measure expansion history scientists used type 1a supernovas as their standard candle one example of a standard candle might be a 100-watt light bulb you could have a bunch of these things sitting around in your room at different distances from you then the more distant ones will appear fainter and more nearby ones will appear brighter type 1a supernovas are always consistently brilliant no matter where they occur in space a supernova is the colossal explosion of a star at the end of its life it just goes come back and it occurs when a dying star known as a white dwarf goes through a nuclear runaway and just literally blows itself to smithereens we find the type 1a supernovae in very distant galaxies so they look really faint and they then we compare them with type 1a supernovae in nearby galaxies whose distance work distances were measured using Cepheid variables or some other technique using these type 1a supernovas two different teams set out in the nineteen nineties to measure the deceleration rate of the universe but to capture supernovas as they occur astronomers had to put the universe on surveillance you can compare this a little bit too perhaps surveying a casino so all these cameras are on all the time and most of the time they don't find much of anything interesting but occasionally they find what they're looking for you have to look at lots of galaxies so what we did is we took large telescopes with cameras that have wide fields of view about is y to save with of the full moon and we took many snapshots of space using this widefield camera and each each snapshot contains tens of thousands of galaxies and by comparing the apparent brightness of the distant one days with those of the nearby like one is in nearby galaxies we can get the distance of the distant galaxies and hence the amount of time that we're looking back in the history of the universe after the two teams study the results of 60 type 1a supernovas scientists were shocked at their results the universe wasn't slowing down its expansion was speeding up we all expected that expansion to be slowing down with time because after all all of the galaxies are pulling on one another was how confident we are going to measure the rate at which the universe was slowing down and then we found of course a negative answer the universe is not slowing down it's speeding up this was just a big mystery that is really really weird you know we expected to measure some amount of slow down and instead it's expanding more quickly that's like the wrong sign right we were really afraid that we had gotten completely the wrong answer we rechecked our measurements we checked the analysis a bunch of people on each of the two teams that the measurements in the analysis independently and kept getting getting the same result one of the greatest shocks in the world of cosmology just in the last few years has been the realization that our universe is accelerating this repulsive force driving the universe was called dark energy an invisible energy that was nothing anyone expected or understood it suggests that over the largest distances in the universe there's a repulsive effect that dominates over gravity and dark energy is creating space taking galaxies along for the ride this energy that appears to fill the universe and stretch the expansion of the universe faster and faster with time is now known as as dark energy so here I throw the Apple and initially its decelerating and then dark energy makes it accelerate away from me you throw the Apple and it just zooms away faster and faster with time like the Apple forever traveling into space galaxies are being carried away as more space is created so if you could imagine you know a classroom populated by chairs and those chairs are slowly getting further apart from one another within a classroom because of all the chairs are being stretched apart like an expanding universe no matter which chair you sit on you will find all chairs are moving away from you so the chairs are not really expanding about the chairs of the same sides really what's happening is that the room is getting bigger this space in between the chairs is being stretched apart more space is being created in between the galaxies have individual galaxies remaining of constant size in a universe where all of space is getting bigger and bigger dark energy is very different from dark matter it doesn't clump up like galaxies do in clusters are like stars do in galaxies instead it appears to be pretty uniform and we find the same amount of acceleration no matter which direction we look at its probably smooth although some people believe that maybe structure and its distribution an essentialist dark energy is the energy of the vacuum the energy of nothing evening nothingness has energy and it's pushing the galaxies apart creating a runaway universe it appears dark energy and Dark Matter have been at war with one another since the beginning of time science believes dark energy was created along with for thousands of years we have looked at the night sky and believed that the illuminated stuff was all that made up our universe scientists now realize it's not what shines in the life but what hides in the dark that holds the true secrets of our sky there is mysterious dark matter that binds stars and galaxies together and strange particles like wimps Axion's and macho's might be to blame and there is a dark repulsive energy that is creating space in the universe but driving the galaxies further and further apart to a dismal fate combined dark matter and dark energy makeup ninety-six percent of the universe and uncovering their secrets is like making the one-in-a-million shot if uncovered the ultimate fate of the universe might be revealed really crash and burn in a horrific collision of gravitational forces for you know dark energy tear the universe apart the betting is the universe will die in ice understanding these two quantities stop matter and dark energy is really continental to understand the universe this is a trip to the dark side of the universe this is the hunt for dark matter and dark energy dark matter is unlike anything we have ever encountered on earth billions of these strange particles pass through everything they encounter each second they are so massive in weight they have the power to influence the galaxies how they form and how fast they spin Dark Matters invisible presence is everywhere or so it seems science has not directly proven dark matter particles exist there are many suspects but no answers and observing something you can't see isn't easy that doesn't emit light and it doesn't absorb light it doesn't interact with light at all not only does it not shine you can easily see it in obscuration but the evidence is there science knows it every textbook on the planet earth says that the universe is made out of atoms and some subatomic particles well all those textbooks are wrong and they are going underground to prove it when they hear about this invisible matter called dark matter they say bah humbug show me proof that Dark Matter exists sudan Minnesota 200 miles from any major city lights a perfect place for hunting dark matter but not for obvious reasons so you think we'd want to look up in the sky for dark matter that's where dark matter is coming from after all but instead we're going to Don our helmets and we're gonna walk down into this mine 2431 feet underground is the Sudan National Laboratory an abandoned iron mine reconfigured into a research facility this is just one lab of many around the world going underground to shield experiments from cosmic rays each are racing to detect dark matter an invisible particle that has only been indirectly observed but never captured we've been at this for now a decade and we have yet to see a dark matter particle the hunt for dark matter started almost a century ago astronomers finally had the tools to see deep into the night sky and the questions began so was until the nineteen twenties but the technology developed well enough so we could take little fuzzy patches that people notice in our telescopes and resolve them and figure out what they are then Edwin Hubble shocked the world and declared the universe was bigger than just the Milky Way people realize that some of these little fuzzy patches are separate galaxies just like our Milky Way galaxy as astronomers discover new galaxies Caltech professor Fritz wiki looked up to the neighboring Coma Cluster of galaxies and observed something strange when he measured what the motions were in the coma cluster of galaxies he got an estimate for how much mass there was in that custom that he compared it to how much mass you could actually see by looking at the galaxies something didn't add up the galaxies were moving too fast within the cluster for the amount of illuminated stuff he could see by his calculations there should have been a hundred sixty times more illuminated mass to account for the random speeds of galaxies in the cluster something else was affecting their motions but what was it he analyzed their motions and concluded that the cluster could not be stable unless there was a large amount of dark matter present in 1933 he was one of the first people to really grasp the significance of the presence of dark matter he called it missing matter an invisible mass that was gravitationally attractive and was able to affect the speeds of entire galaxies in a cluster revolutionary thinking yes but the discovery was largely ignored I think that people took this wiki seriously but they didn't jump to any conclusions this is a time when the universe was just beginning to be explored it was the nineteen twenties when we first realized there were galaxies outside our own but we didn't know back then was whether it was simply galaxies or stars or gas or dust that we couldn't see whether it's something truly different psyches observations were based on measuring the mass in the stars and galaxies but how do you weigh stuff in space can go and put the Sun on the scale little bit hard but what you can do is you can measure how fast the planets are moving around this and the more stuff there is in the Sun the faster those planets have to move