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	2022-10-12: The REAL Possibility of Mapping Alien Planets! 04:36: ... seen  through the gravitational field of a   giant galaxy cluster. If the alignment is close enough, we can see an Einstein Ring, like ... 10:07: ... that the scientists called this  a string of pearls. That first cluster of   craft was the first pearl. Even if that wave  ...
	2022-09-21: Science of the James Webb Telescope Explained! 09:11: This is the SMACS 0723 cluster. 09:24: For comparison, this is the Hubble image of the same cluster. 09:28: Those white blobby things are massive elliptical galaxies of the cluster, several billion light years away. 09:36: These arcs are much more distant galaxies whose light is warped by the gravitational field of the cluster.
	2022-06-01: What If Physics IS NOT Describing Reality? 15:25: ... believed that the oddly blue   stars at the cores of globular clusters may have  resulted from stellar mergers in these ...
	2022-05-25: The Evolution of the Modern Milky Way Galaxy 10:12: ... to pick out the little stripe  of stars, like GD-1: a globular cluster that’s in   the process of being pulled apart. On the ... 02:19: ... wayward stars and ancient,  dense mini-galaxies called globular clusters.   But mostly the halo is made of dark matter,  which also suffuses ... 06:57: ... not born in our galaxy.  We’ve also found a group of 13 globular clusters   with matching orbital properties and spectra  that were probably ...
	2022-05-18: What If the Galactic Habitable Zone LIMITS Intelligent Life? 08:01: ... gas cloud like pebbles in a   pond, forming a growing cluster that would become  the Milky Way’s bulge. As the galactic bulge ...
	2022-05-04: Space DOES NOT Expand Everywhere 01:24: ... of their galaxies, galaxies whirl and collide in local groups and clusters. But if you expand your view to large enough scales, that local motion or ...
	2022-01-19: How To Build The Universe in a Computer 05:14: For a modern one-million particle simulation of a star cluster, that’s a trillion computations per time step. 05:26: ... formation of individual galaxies, as well as the evolution of giant clusters of ... 09:43: ... available,   using parallelyzed code on  modern computing clusters, we can produce some pretty insane ... 05:26: ... formation of individual galaxies, as well as the evolution of giant clusters of ... 09:43: ... available,   using parallelyzed code on  modern computing clusters, we can produce some pretty insane ...
	2021-12-20: What Happens If A Black Hole Hits Earth? 15:30: ... galaxies? Given that the new MOND has trouble explaining the Bullet cluster, my guess is that it also fails to explain other anomalous galaxies. If ...
	2021-11-10: What If Our Understanding of Gravity Is Wrong? 00:42: ... the gravity of visible matter is also way too weak to hold galaxy clusters together, or to bend the path of light to the degree seen in ... 05:14: If you tune MOND to work for galaxies and then apply it to galaxy clusters, you do get rid of the need for some of the dark matter but not all of it. 05:22: You still need about 20% of the current dark matter requirement to explain all the gravity we see in clusters. 05:38: ... the fact that you still need some type of physical dark matter in clusters is seen as a strong point against MOND in its first incarnation at ... 11:56: It was able to clump in the right  way to kickstart cluster formation. 12:07: ... the newly-dubbled  RelMOND - relativistic MOND - works for galaxy clusters and keeps stars from exploding  - but the authors are ... 12:25: Modified gravity theories still can’t explain the Bullet Cluster - and I don’t have time to get into that and we’ve covered it before. 12:33: ... I’ll just say that when galaxy clusters collide and the dark matter gets ripped away from the light matter - it ... 12:45: ... are MOND proposals which claim  to address this, but the Bullet Cluster might be the most awkward result  for modified gravity ... 12:25: Modified gravity theories still can’t explain the Bullet Cluster - and I don’t have time to get into that and we’ve covered it before. 11:56: It was able to clump in the right  way to kickstart cluster formation. 00:42: ... the gravity of visible matter is also way too weak to hold galaxy clusters together, or to bend the path of light to the degree seen in ... 05:14: If you tune MOND to work for galaxies and then apply it to galaxy clusters, you do get rid of the need for some of the dark matter but not all of it. 05:22: You still need about 20% of the current dark matter requirement to explain all the gravity we see in clusters. 05:38: ... the fact that you still need some type of physical dark matter in clusters is seen as a strong point against MOND in its first incarnation at ... 12:07: ... the newly-dubbled  RelMOND - relativistic MOND - works for galaxy clusters and keeps stars from exploding  - but the authors are ... 12:33: ... I’ll just say that when galaxy clusters collide and the dark matter gets ripped away from the light matter - it ...
	2021-07-21: How Magnetism Shapes The Universe 00:56: And it governs the formation of every major structure in the universe, from the smallest moon to the largest cluster of galaxies.
	2021-04-13: What If Dark Matter Is Just Black Holes? 07:58: ... compact mass like a brown dwarf star, neutron star, Dyson sphere or a cluster of Reaper capital ships - as long as they’re massive, compact, and dwell ...
	2021-01-26: Is Dark Matter Made of Particles? 00:23: ... the orbits of stars and galaxies, in way light bends around galaxies and clusters, in the clumpiness of the cosmic background radiation, and ... 03:45: ... of galaxies, and how it drives the orbits of galaxies inside galaxy clusters, and by the way it bends light around galaxies and ... 00:23: ... the orbits of stars and galaxies, in way light bends around galaxies and clusters, in the clumpiness of the cosmic background radiation, and ... 03:45: ... of galaxies, and how it drives the orbits of galaxies inside galaxy clusters, and by the way it bends light around galaxies and ...
	2020-11-18: The Arrow of Time and How to Reverse It 05:10: ... by having a weird distribution of velocities, but you can also do it by clustering the particles in one spot in the available space. Let’s give those ... 05:43: ... the same actually. Random velocity directions will tend to spread this cluster apart in both time ... 07:17: ... racing away from each other, which means they were once more closely clustered. This is the expansion of the universe, and it’s the manifestation of the ... 05:10: ... by having a weird distribution of velocities, but you can also do it by clustering the particles in one spot in the available space. Let’s give those ...
	2020-07-28: What is a Theory of Everything: Livestream 00:00: ... at the largest possible scales the scales of galaxies and super clusters of galaxies and all and the largest things in the universe and that's ...
	2020-07-20: The Boundary Between Black Holes & Neutron Stars 12:03: We’re shipping it to you from a little star cluster in Sagittarius - made locally from humanely sourced o-giant star of course.
	2020-06-08: Can Viruses Travel Between Planets? 14:44: ... the cosmic microwave background speckles, and in things like the bullet cluster where it seems like that the dark matter is separated from the stars and ...
	2020-05-04: How We Know The Universe is Ancient 04:40: ... as they’re tugged by the gravitational fields of nearby galaxies and clusters. We can deal with these “peculiar velocities” just by averaging over many ... 09:39: ... some moments of confusion. For a while we thought we’d found globular clusters - ancient, dense groups of stars - that were 15 billion years old. As ... 11:07: ... be found by adding up the gravitational effect in galaxies and in galaxy clusters, and also by tracking the past expansion history of the universe to ... 04:40: ... as they’re tugged by the gravitational fields of nearby galaxies and clusters. We can deal with these “peculiar velocities” just by averaging over many ... 09:39: ... some moments of confusion. For a while we thought we’d found globular clusters - ancient, dense groups of stars - that were 15 billion years old. As ... 11:07: ... be found by adding up the gravitational effect in galaxies and in galaxy clusters, and also by tracking the past expansion history of the universe to ... 09:39: ... some moments of confusion. For a while we thought we’d found globular clusters - ancient, dense groups of stars - that were 15 billion years old. As bad ...
	2020-01-27: Hacking the Nature of Reality 12:13: ... that the largest structures in the universe today - galaxies and galaxy clusters - as collapsed from quantum fluctuations in the extremely early ...
	2019-12-09: The Doomsday Argument 16:21: ... that is that the baryon acoustic oscillation signatures seen in galaxy clusters are an independent measure of curvature, and these point to a much ...
	2019-12-02: Is The Universe Finite? 06:02: ... passes through a universe full of galaxies and galaxy clusters - all of which have enormous gravitational fields that act as lenses, ... 08:39: In short - lensing by a cluster of galaxies tends to draw rays of light from different blobs together. 08:46: A random distribution of blobs ends up with slight clusterings. 06:02: ... passes through a universe full of galaxies and galaxy clusters - all of which have enormous gravitational fields that act as lenses, ...
	2019-07-25: Deciphering The Vast Scale of the Universe 07:03: That’s the Virgo cluster – the nearest big city, of which our local group is an outlying suburb. 07:18: ... the Milky Way, and a hundred thousand more galaxies belong Laniakea, a cluster of superclusters some 500 million light years ...
	2019-06-17: How Black Holes Kill Galaxies 02:54: ... what we see when we look out into the Universe so galaxies first grew in clusters in the densest parts of the Universe Places where enormous worlds of ... 05:24: ... should've kept forming stars Giant reservoirs of gas flowed into those clusters from the outside Universe In our simulations of the Universe clustered ... 07:21: ... star formation shifted towards the outer regions further from the giant clusters for the past several Billion years the cosmic star formation rate has ... 05:24: ... clusters from the outside Universe In our simulations of the Universe clustered ellipticals end up much bigger and bluer Due to Billions of more years ... 02:54: ... what we see when we look out into the Universe so galaxies first grew in clusters in the densest parts of the Universe Places where enormous worlds of ... 05:24: ... should've kept forming stars Giant reservoirs of gas flowed into those clusters from the outside Universe In our simulations of the Universe clustered ... 07:21: ... star formation shifted towards the outer regions further from the giant clusters for the past several Billion years the cosmic star formation rate has ...
	2019-05-16: The Cosmic Dark Ages 03:52: ... tattered fragments of neutral gas drifting between the growing galaxy clusters. ...
	2019-04-24: No Dark Matter = Proof of Dark Matter? 00:03: ... Swiss astrophysicists Fritz Zwicky noticed that the galaxies in the Coma Cluster were moving too quickly to remain gravitationally bound within that ...
	2019-03-28: Could the Universe End by Tearing Apart Every Atom? 00:25: ... effect of dark energy it's in the vast tracts of space between galaxy clusters over countless trillions of cubic light-years of emptiness the dark ... 09:15: ... until near the end, around a billion years before the big rip, galaxy clusters are ripped apart. At 60 million years and counting, the Milky Way is ... 00:25: ... effect of dark energy it's in the vast tracts of space between galaxy clusters over countless trillions of cubic light-years of emptiness the dark ... 09:15: ... until near the end, around a billion years before the big rip, galaxy clusters are ripped apart. At 60 million years and counting, the Milky Way is ...
	2019-02-20: Secrets of the Cosmic Microwave Background 12:34: ... numbers when we look at the dark matter content in modern galaxies and clusters and the dark energy based on measuring the accelerating expansion rate ...
	2019-02-07: Sound Waves from the Beginning of Time 09:37: But you should also have a slight overabundance of galaxies at exactly 150 megaparsecs from those clusters. 10:10: That's the clustering from the giant dark matter density peaks. 09:37: But you should also have a slight overabundance of galaxies at exactly 150 megaparsecs from those clusters.
	2019-01-24: The Crisis in Cosmology 07:50: ...would go on to collapse into the vast clusters of galaxies of the modern universe.
	2018-11-14: Supersymmetric Particle Found? 06:31: ANITA is a cluster of radio antennae that hovers 37 kilometers above Antarctica.
	2018-08-23: How Will the Universe End? 07:30: Some have grown to masses of up to 100 trillion suns, having swallowed good-sized bites from entire galaxy clusters.
	2018-08-15: Quantum Theory's Most Incredible Prediction 10:28: Since 2008, all calculations are done on large, supercomputing clusters.
	2018-07-18: The Misunderstood Nature of Entropy 07:04: That's why these similarly-shaped distributions on the Go board correspond to the same macrostate, while the clustered spread does not. 07:57: So our smoothly spread out equilibrium Go board has a high entropy and our clustered board has low entropy. 07:04: That's why these similarly-shaped distributions on the Go board correspond to the same macrostate, while the clustered spread does not. 07:57: So our smoothly spread out equilibrium Go board has a high entropy and our clustered board has low entropy. 07:04: That's why these similarly-shaped distributions on the Go board correspond to the same macrostate, while the clustered spread does not.
	2018-05-09: How Gaia Changed Astronomy Forever 05:46: And mapping globular clusters and dwarf galaxy orbits also tells us about future interactions with the Milky Way. 07:11: These dynamically connected flows of stars, once bound together as a globular clusters or dwarf galaxies. 09:52: Super advanced civilizations clustered around black holes, in an utterly dark universe. 05:46: And mapping globular clusters and dwarf galaxy orbits also tells us about future interactions with the Milky Way. 07:11: These dynamically connected flows of stars, once bound together as a globular clusters or dwarf galaxies.
	2018-04-25: Black Hole Swarms 01:56: And the densest, stellar objects, like black holes, sink to the centers of galaxies or star clusters. 03:46: Our galaxy is surrounded by these things called globular clusters. 04:08: Because globular clusters are much more massive than a single black hole, they reach the galactic center a lot will quickly. 04:15: Over the life of the Milky Way, they have piled up in the galactic core, forming a giant nucleus star cluster. 04:22: Those globular clusters must have been full of ancient black holes, which would be carried to the core with their parent cluster. 01:56: And the densest, stellar objects, like black holes, sink to the centers of galaxies or star clusters. 03:46: Our galaxy is surrounded by these things called globular clusters. 04:08: Because globular clusters are much more massive than a single black hole, they reach the galactic center a lot will quickly. 04:22: Those globular clusters must have been full of ancient black holes, which would be carried to the core with their parent cluster.
	2018-04-18: Using Stars to See Gravitational Waves 01:36: ... are calculating whether these black holes may have grown inside globular clusters, where the stellar density is so high that we expect lots of black hole ...
	2018-03-28: The Andromeda-Milky Way Collision 09:49: ... those first stars were forming, presumably some sort of proto-galactic clusters. ... 10:25: ... consistency of the dark matter mass measurements of galaxies and galaxy clusters from gravitational lensing versus ... 10:33: ... but still comes together under gravity, for example, in the Bullet Cluster. ... 09:49: ... those first stars were forming, presumably some sort of proto-galactic clusters. ... 10:25: ... consistency of the dark matter mass measurements of galaxies and galaxy clusters from gravitational lensing versus ...
	2018-01-31: Kronos: Devourer Of Worlds 00:50: And they form in the many thousands before being ejected from their birth clusters to wander the galaxy. 01:02: However, if the gravitational connection between a pair of stars is strong enough, they might be ejected from the cluster as a binary pair. 04:47: ... each other's motion so closely unless they were ejected from their birth cluster as a binary ... 00:50: And they form in the many thousands before being ejected from their birth clusters to wander the galaxy.
	2017-11-02: The Vacuum Catastrophe 09:42: They're too hot to pull into the deep dark matter wells that we see in galaxy clusters. 10:36: That energy comes from shocks that develop as the material flows in the gravitational field of surrounding clusters. 09:42: They're too hot to pull into the deep dark matter wells that we see in galaxy clusters. 10:36: That energy comes from shocks that develop as the material flows in the gravitational field of surrounding clusters.
	2017-10-25: The Missing Mass Mystery 01:12: Yet, what if I told you that all of the stars and galaxies and galaxy clusters only comprise 10% of the light sector? 03:23: ... much hydrogen to start with than we actually see today in galaxies and clusters. ... 04:00: These speckles are fluctuations in density that would later collapse to become the galaxy clusters. 05:08: ... to do its work and collapse these faint fluctuations into gargantuan clusters of ... 06:15: We typically see that stuff inside galaxy clusters where the plasma is relatively dense and is energized by the light of the galaxies themselves. 06:39: Absorption features in the light of distant quasars reveal this gas lurking between clusters of galaxies. 07:12: ... giant filaments that form the cosmic web stretching in between galaxy clusters. ... 07:23: That material would be cooler than the clusters themselves, but should at least be hot enough to form a plasma. 10:22: ... space, still flowing with rivers of dark matter into the galaxy clusters. ... 01:12: Yet, what if I told you that all of the stars and galaxies and galaxy clusters only comprise 10% of the light sector? 03:23: ... much hydrogen to start with than we actually see today in galaxies and clusters. ... 04:00: These speckles are fluctuations in density that would later collapse to become the galaxy clusters. 05:08: ... to do its work and collapse these faint fluctuations into gargantuan clusters of ... 06:15: We typically see that stuff inside galaxy clusters where the plasma is relatively dense and is energized by the light of the galaxies themselves. 06:39: Absorption features in the light of distant quasars reveal this gas lurking between clusters of galaxies. 07:12: ... giant filaments that form the cosmic web stretching in between galaxy clusters. ... 07:23: That material would be cooler than the clusters themselves, but should at least be hot enough to form a plasma. 10:22: ... space, still flowing with rivers of dark matter into the galaxy clusters. ...
	2017-08-02: Dark Flow 00:30: Galaxies whirl within the gravitational fields of giant clusters. 01:05: ... of the cosmic microwave background suggest that galaxy clusters across the cosmos may be moving ever so slightly towards the same point ... 03:39: ... the most massive galaxy clusters in our universe are vast conglomerations of thousands of galaxies and ... 04:01: As a result, when we look at the cosmic microwave background through one of these clusters, we see that its energy is boosted just slightly. 04:11: This allows astronomers to find extremely distant galaxy clusters just by studying the CMB. 04:24: ... a galaxy cluster has some extra peculiar velocity in addition to the Hubble flow, then ... 04:36: It sort of resets the apparent velocity, the frame of reference of that patch of the CMB to the peculiar velocity of the cluster. 04:49: And that shift can tell us the peculiar velocity of the cluster. 05:02: A KSZ measurement from a single cluster isn't very useful. 05:07: But what if you could measure the effect from hundreds of clusters across the observable universe? 05:17: ... microwave background to build up a peculiar velocity map of around 700 clusters in all directions on the sky and out to billions of light ... 05:32: Once you factor out the Hubble flow, on average, those clusters seem to be drifting in the same direction. 06:44: Analyzing around 1,000 clusters using the new data, the Planck satellite team say that no dark flow is apparent. 07:36: ... now think that this might be the center of the Laniakea super cluster, which is a vast cluster of clusters that encompasses hundreds of ... 08:58: ... a different bubble of observable universe with more galaxies, more clusters, more dark ... 09:30: ... map of the cosmic microwave background so that we can measure more clusters to greater distances and high ... 05:02: A KSZ measurement from a single cluster isn't very useful. 00:30: Galaxies whirl within the gravitational fields of giant clusters. 01:05: ... of the cosmic microwave background suggest that galaxy clusters across the cosmos may be moving ever so slightly towards the same point ... 03:39: ... the most massive galaxy clusters in our universe are vast conglomerations of thousands of galaxies and ... 04:01: As a result, when we look at the cosmic microwave background through one of these clusters, we see that its energy is boosted just slightly. 04:11: This allows astronomers to find extremely distant galaxy clusters just by studying the CMB. 05:07: But what if you could measure the effect from hundreds of clusters across the observable universe? 05:17: ... microwave background to build up a peculiar velocity map of around 700 clusters in all directions on the sky and out to billions of light ... 05:32: Once you factor out the Hubble flow, on average, those clusters seem to be drifting in the same direction. 06:44: Analyzing around 1,000 clusters using the new data, the Planck satellite team say that no dark flow is apparent. 07:36: ... be the center of the Laniakea super cluster, which is a vast cluster of clusters that encompasses hundreds of millions of light years and several hundred ... 08:58: ... a different bubble of observable universe with more galaxies, more clusters, more dark ... 09:30: ... map of the cosmic microwave background so that we can measure more clusters to greater distances and high ...
	2017-06-07: Supervoids vs Colliding Universes! 04:05: A photon entering a matter-rich galaxy cluster gets an energy boost as it falls into the cluster's gravitational well. 04:13: But by the time the photon is on its way out, the expansion of the universe has actually stretched out the cluster, weakening its gravitational pull. 04:05: A photon entering a matter-rich galaxy cluster gets an energy boost as it falls into the cluster's gravitational well.
	2017-05-31: The Fate of the First Stars 02:18: Today, they're found in the galactic bulge or in globular clusters, which are ancient, dense islands of stars that orbit far out in the galactic halo. 09:04: ... Clusters of giant stars become clusters of giant black holes, which, in turn, ... 02:18: Today, they're found in the galactic bulge or in globular clusters, which are ancient, dense islands of stars that orbit far out in the galactic halo. 09:04: ... Clusters of giant stars become clusters of giant black holes, which, in turn, ...
	2017-04-19: The Oh My God Particle 08:09: We do see more than the average number coming from the direction of the Ursa Major cluster, but there's no obvious source there.
	2017-02-02: The Geometry of Causality 11:41: It's a beautiful barred spiral galaxy in the Fornax cluster.
	2016-10-12: Black Holes from the Dawn of Time 05:44: As the heavier ones buzz around the galaxy, they should pull apart loosely bound binary systems and have an effect on the structure of star clusters. 06:01: But we see loosely bound binaries, and normal star clusters, and plenty of neutron stars. 05:44: As the heavier ones buzz around the galaxy, they should pull apart loosely bound binary systems and have an effect on the structure of star clusters. 06:01: But we see loosely bound binaries, and normal star clusters, and plenty of neutron stars.
	2016-09-29: Life on Europa? 03:57: ... support all sorts of complex life-- forests of tube worms and clusters of clams and mussels that are crawling with crabs, snails, and ...
	2016-07-06: Juno to Reveal Jupiter's Violent Past 07:53: However, the Nice Model posits that the orbits of the four gas giants were much more tightly clustered back then.
	2016-06-15: The Strange Universe of Gravitational Lensing 03:30: ... through the deep gravitational wells of intervening galaxies and galaxy clusters, they are greatly magnified in brightness and stretched into arcs and ... 04:27: We've weighed many galaxies and galaxy clusters this way. 03:30: ... through the deep gravitational wells of intervening galaxies and galaxy clusters, they are greatly magnified in brightness and stretched into arcs and ... 04:27: We've weighed many galaxies and galaxy clusters this way.
	2016-04-27: What Does Dark Energy Really Do? 11:23: These surveys don't measure dark matter content of all of their galaxy clusters.
	2016-04-13: Will the Universe Expand Forever? 04:13: ... largest scales, billions of light years, all of the galaxies and galaxy clusters are very evenly dusted across all of ...
	2016-03-09: Cosmic Microwave Background Challenge 02:10: ... us, right now, the universe has expanded so that the galaxies and clusters that those blobs evolve into are now 1,100 times further away, giving us ...
	2016-03-02: What’s Wrong With the Big Bang Theory? 10:38: That works on the largest scales in which galaxies and galaxy clusters are a speckled foam on top of a much vaster space time.
	2016-02-24: Why the Big Bang Definitely Happened 05:16: Very, very tiny fluctuations that would let it collapse on themselves to form galaxies and clusters of galaxies. 05:23: ... from a smattering of tiny fluctuations to a network of giant galaxy clusters, is also evidence that the Big Bang picture is ... 06:21: The fancy name is baryon acoustic oscillations which cause ring-like clustering of the CMB fluctuations. 05:16: Very, very tiny fluctuations that would let it collapse on themselves to form galaxies and clusters of galaxies. 05:23: ... from a smattering of tiny fluctuations to a network of giant galaxy clusters, is also evidence that the Big Bang picture is ...
	2016-02-17: Planet X Discovered?? + Challenge Winners! 05:06: When the clock is approaching, its ticks are more clustered than when it's moving away.
	2015-09-30: What Happens At The Edge Of The Universe? 01:37: ... is currently 46 billion light years to whatever galaxy or galaxy clusters that blob evolved into, racing away from us with the expanding universe, ... 04:55: And presumably, a pretty similar distribution of galaxies and clusters all around you. 08:16: The same with galaxy clusters. 08:18: The galaxy orbits give us a mass for the dark matter in the clusters and the lensing gives us a mass consistent with this. 01:37: ... is currently 46 billion light years to whatever galaxy or galaxy clusters that blob evolved into, racing away from us with the expanding universe, ... 04:55: And presumably, a pretty similar distribution of galaxies and clusters all around you. 08:16: The same with galaxy clusters. 08:18: The galaxy orbits give us a mass for the dark matter in the clusters and the lensing gives us a mass consistent with this.
	2015-09-23: Does Dark Matter BREAK Physics? 01:09: And galaxy clusters do this all the time, turning the background universe into a funhouse mirror of stretched out and duplicated galaxies. 01:22: But again, we find the clusters appear to have way more mass than we see in the stars alone, that is if we understand gravity. 01:52: Gravity just behaves differently on the vast scales of galaxies and clusters. 04:49: Say hello to the Bullet Cluster. 04:51: It's actually two clusters that smashed right through each other. 04:54: The gas was ripped away from the stars and now lives between the clusters. 04:58: In the Bullet Cluster, most of the mass actually is in the gas. 05:02: So if dark matter really comes from weirdly behaving gravity, then the cluster's gravity should stay concentrated on the gas. 05:25: And we see that in the Bullet Cluster, the dark matter is with the stars. 05:45: It has to be pretty slow moving, or cold, because we know that dark matter clumps together gravitationally to build galaxies and clusters. 05:59: ... smooth ocean of orange plasma to today's highly structured universe of clusters and galaxies, something had to act with enough gravity to pull stuff ... 01:09: And galaxy clusters do this all the time, turning the background universe into a funhouse mirror of stretched out and duplicated galaxies. 01:22: But again, we find the clusters appear to have way more mass than we see in the stars alone, that is if we understand gravity. 01:52: Gravity just behaves differently on the vast scales of galaxies and clusters. 04:51: It's actually two clusters that smashed right through each other. 04:54: The gas was ripped away from the stars and now lives between the clusters. 05:02: So if dark matter really comes from weirdly behaving gravity, then the cluster's gravity should stay concentrated on the gas. 05:45: It has to be pretty slow moving, or cold, because we know that dark matter clumps together gravitationally to build galaxies and clusters. 05:59: ... smooth ocean of orange plasma to today's highly structured universe of clusters and galaxies, something had to act with enough gravity to pull stuff ... 05:02: So if dark matter really comes from weirdly behaving gravity, then the cluster's gravity should stay concentrated on the gas.
	2015-02-25: How Do You Measure the Size of the Universe? 01:47: Each raisin represents a cluster of galaxies in the dough space. 02:01: Galaxy clusters aren't expanding and neither are individual galaxies, or the Earth, or people, or trees. 02:05: It's just the relatively empty space between those large clusters of galaxies. 02:01: Galaxy clusters aren't expanding and neither are individual galaxies, or the Earth, or people, or trees. 02:05: It's just the relatively empty space between those large clusters of galaxies.

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