Space Time explores the outer reaches of space, the craziness of astrophysics, the possibilities of sci-fi, and anything else you can think of beyond Planet Earth with our astrophysicist host: Matthew O’Dowd.
Episodes released every Wednesday afternoon!
Matt O'Dowd spends his time studying the universe, especially really far-away things like quasars, super-massive black holes, and evolving galaxies. He uses telescopes in space to do it. Matt completed his Ph.D. at NASA's Space Telescope Science Institute, followed by work at the University of Melbourne and Columbia University. He's now a professor at the City University of New York's Lehman College and an Associate at the American Museum of Natural History's Hayden Planetarium.
Previous host Gabe Perez-Giz is an astrophysicist who studies black hole physics. He received his Ph.D. from Columbia University and also hosted PBS Infinite Series.

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  1. Jolez _

    So what is the average distance between me and me?

  2. Manus Artifex

    Anxious dark matter

  3. adrian tausheck

    Also my theory predicts 3 plus 1 dimensions but another set of dimensions pop in and out of existence depending on how fast something is traveling but it only happens at very high speeds .... Also my theory says that the speed of light is actually the idea of anything going slower than the speed of light is what makes up time.... The big bang is happening along a fuse and the universe is an infinite thing constantly being made and also constantly being in the end parts of entropy

  4. adrian tausheck

    I have a theory of everything but most people won't listen to me maybe you guys will? No one can follow the math my math teachers don't even know basic algebra apparently because that's all I'm using as my demonstration ... Anyways my theory of everything predicts gravity AND quantum mechanics .... Also some other things .... Matt please PM me so I can talk to you about it and maybe we can share the victory of the discovery... I need help with one part of my equation .. it suggests that dark matter are leftovers from angular momentum and dark energy is the angular momentum... Allow me to show you what I mean

  5. Sister of Gaia

    If you take the remove the first 5 00000 from the quantum vacuum number measurment of the Universe. It would explode 💥 and we would not be here 📌

  6. 211212112

    I see human extinction like the drunk mans walk. Eventually he will end up in the ditch

  7. Pronator Tendon

    We're trying to quantify an analog cosmos with digital math. We're amazingly fortunate to have figured out as much as we have.

  8. Alex Weddle

    The white hole and black holes *cough* racism

  9. Juggernaut

    I want to go on Saturn even if its gas

  10. DarthVader DaGreat

    So how many trees need to be planted to Raise that Oxygen Level in the Atmosphere??

  11. Totumfacky

    I watched a lot of videos with this guy and... I can't like him. I just hate the way he speaks, his manner... I wish PBS could record again this all those videos with someone else's.

  12. Stan Stockton

    "Coypurr belt"

  13. kermitefrog64

    This is not surprising. As science analyzes evidence there will be changes of understanding.

  14. kermitefrog64

    It makes one wonder if we will see a shift of the Aurora Borealis and see it pop up in areas that we have not seen in our life time.

  15. James Brunton

    I don't like the photon clock,it doesn't make sense and your just confusing everyone else by saying this. I'd rather believe there is a time particle that is slowed down by the Higgs field.

  16. Gaberal

    Dear operator , Please code my life better !

  17. James Brunton

    Sounds alot like gravity, hopefully you's are smart enough to put 2 and 2 together.

  18. Thomas Lucas

    How far can mans signals travel until the inverse square law weakens the signal too low to distinguish from the background noise? Why doesn't anyone mention this limitation? Is their a table of how far EM radiation can travel pr watt until it fades out?

  19. Rigel

    There is one thing I would've wanted to see here to be entirely honest, you were exclusively talking about fission concepts while I would've loved to see some fusion ones we might want to use in the future, the ITER in france for example.

  20. Dave Andrews

    Albert Einstein’s theory of relativity explains the effect of gravity but doesn’t explain what causes it. It actually seems very simple. Gravity is not a force, it’s an effect produced by the time velocity differential that matter produces from the displacement of space-time. More simply put the time velocity at the center of the earth is slower than at the surface of the earth. As such, the two time velocities cannot be reconciled without being equal. Gravity is the effect produced by the time velocity trying to equalize between the center of the earth and the surface of the earth or any other point in the universe for that matter. When matter exists it displaces space-time. The more matter in one location the more space-time that is displaced and the more the time velocity difference the more gravitational effect. This is why a black hole has a larger gravitational effect than the earth. As far as I can tell I’m the first to propose this theory so if it pans out as I believe it will I claim discovery with god’s help of course. This theory meshes very well with Einstein’s theory of relativity. Gravitational waves are actually time velocity ripples in space-time generated by a massive space time altering event. In the case of black holes the gravitational effect to time velocity relationship changes as soon as the black hole forms because spacetime is non-existent inside of the black hole. The gravitational effect is then controlled by the size of the surface area of the black hole because time velocity at the surface is zero. This could explain why the rotation of galaxies is different than expected. This would then in turn explain why we can’t find dark matter - because it doesn’t exist. One more small point, time velocity differential may also cause red shift by causing light to change from particle to wave and back by it’s angular influence as light passes by the time velocity anomalies. This may be mistaken for cosmological red shift dispelling the accelerating expanding universe theory. In other words the more time velocity influence light encounters the larger the red shift. This is probably a lot to take in all at once, but at any time velocity it’s certainly worth pondering.

  21. Whitney

    It was the best of times, it was the BLURTS of times? YOU IDIOT!!

  22. Danny

    Yes we can but after 200 years!!!

  23. nnneh1

    Re the bubble universe bit at the end, surely the bubbles don't actually exist except as a construct relative to the observer? In which case, isn't the idea of bubbles colliding bunk?

  24. diego martinez


  25. reuven1961

    I has not been mentioned in the video, but only if one looks separately at the patterns of C or D one gets interference patterns - and the patterns for C and D are shifted relative to each other. Can someone explain why the pattern of C and D together is not an interference ??

  26. weylguy

    Wow - explaining an undetectable form of matter with another undetectable form of matter. Turtles all the way down? But I love this PBS program!

  27. Max Lee

    space is the medium and the origin of possibility. Empty space, compared to anything else in the universe, has the MOST potential; something from nothing baby!

  28. Ken Doggett

    Rendezvous With Rama...another Arthur C. Clarke prediction come true...

  29. Ged Woods

    Are we just intelligent dust mites 🤔

  30. Ged Woods

    A particle fountain

  31. Ronald Sebastian

    there is no dark matter

  32. mettaur01

    Is this where all the perverted Globe Earthers hang out?

  33. TestY

    So does it mean we don't leave in a black hole?

  34. MarketOracleTV

    we should have stayed up those trees

  35. Scoring digits, son.

    Maj kohoni? Nahe!

  36. Hooch Smeeth

    diz guy sux 2 dix 4 free!!! LOOOOOOOOL!!!

  37. kevin ruiters

    @13:19 - "all life clearly descended from the ONE self-replicating molecule...". This is just a fact-free assertion of course since there is no documented observation or verification that life arose from non-living chemicals via random physical or chemical processes all by itself. And just to emphasize the absurdity of this idea: We know when someone/something dies it does not come back to life again all by itself. Never been observed. Plus that just-died someone/thing already has all the biological ingredients lined up in the right order yet it cannot kick-start itself into life. So how much more of an uphill for the random, non-living material to first organize itself into the biological order BEFORE it can do the impossible act of kick-starting itself into life? So far, the evidence for this most important of all issue is, well, .... just hot gas...! There's a simple logical alternative explanation to consider. Just as we know that when looking at a building that there must have been a builder ( whether it was 10 weeks ago or 1000 years ago) or if we look at a painting we KNOW there was a painter because buildings and paintings do not create themselves. In the exact same way when we look at creation we KNOW there was a creator since it couldn't have made itself. There is no way to get from pure material to the complex information filled biological life we see everywhere on earth via purely materialistic processes. How and where would one encounter a purely phyiscal process that gives rise to ABSTRACT information????? Think deeply about that.

  38. Lil Charlie

    'tis not the observer, 'tis the Watcher

  39. Harvey Jess Low

    If you believe in a big bang, then why not more than one?

  40. Robin Brimalm

    Hehe, 0,1c in 20 days is optimal. Steady 1,7g.

  41. Abdulraheem

    I love this works, but why there is no Arabic language? So i can share it with my people 👨‍👨‍👦

  42. PouncingAnt

    Excellent. Sounds like Axions are an elegant solution to at least two big physics problems. Which leaves the question, Why might they not be? Is there anything besides the lack of experimental evidence to justify the title of the video being a question rather than a statement? (Of course, experimental evidence is a requirement of the scientific method, but.. you know how when they hype a particle, then you go and see the particle, and it's not as good as you were expecting...) P.S. A lot of people thought that about the Higgs.... But I thought it was a massive success. P.P.S. Sorry

  43. Amari Reyne

    "The universe may be truly spatially infinite" Even though I already had that idea in my head, hearing the words out loud from someone else really melted my mind. There's so many things we will never even begin to understand before the heat death of our own part of the whole universe. I mean, we used to think the milky way was the whole universe. And we were calling Andromeda an "island universe" What's to make anyone think the universe we observe isn't just one of... Billions? Trillions? Infinite? Universes. Guess we will never know 🤷‍♂️ I havent slept in 27 hours, go easy on me if you reply 😅

    1. Zenothys

      Amari Reyne You have a healthy skepticism and an inspiring curiosity. No reason to worry about responses imo! To give my two cents, space is only as large as needed to contain all possibilities (which I believe isn't infinite, but does inflate fast enough to redefine infinity to some larger number the instant the previous number is defined), and once you hit the "edge" of space, space becomes _time_ and more or less travels back to the Big Bang via the "beloved" Bogoliubov transformation.

  44. xarmanhs h

    This i like

  45. Maaliik Ali

    I came to the comments to see if anyone thought this guy was talking way to fast and the consensus is in, this guy should have a mouth off with Arrow's Felicity Smoak! If you want to be more relatable slow down Partna! Info was great but ya mouth moves at an extreme rate!

  46. Pronator Tendon

    Thank you for doing this without riddling it with ads. That alone makes you worthy of becoming a patron

  47. Cheasy

    a nerd channel and no 60 fps xD yr tittle has been revoked

  48. Anthony Baransky

    What do you hope to learn? It a planet of rocks. Will you end world hunger??? Will you solve this world's energy or pollution problems??? Will you end diseases??? I sincerely doubt it. Your reaching for the stars when your children are staving to death. Fix the earth's problems first then... You have the right to dream!!!

  49. froschers

    there is a tiny mistake at 3:11, his name is ernst heinrich bruns. otherwise, this is a really helpful video :))

  50. Anthony Baransky

    MARS the journey: A continuous waste of money. Here's a list to do first before leaving earth. 1- end world hunger. 2- end homelessness. 3- Find pollution free energy. I could mention a lot more things that are very important but I think those 3 will keep the powers that be quite busy for the next century at least

  51. Mtf

    I used to watch these videos and then, frustrated for not being able to understand, go to the pub . Now I 've thought better and I go to the pub BEFORE watching the videos and suddenly they are crystal clear .

  52. xnonsuchx

    An exact copy of me would be the exact same atoms/particles behaving in the exact same manner, so would have to happen within a spacetime where those atoms/particles have some ability to recombine in the right configuration and where I don't already exist (unless you consider time travel).

  53. Tral Fazz

    Where is 5 million years worth of fuel stored on the sun without burning up?

  54. 1504MBR 1504MBR

    I have a Blazer that's as amazing as a Blazar! I were it with my jeans.

  55. David Brown

    "... a clue that our universe may actually be finite in size ..." Is Milgrom the Kepler of contemporary cosmology? Google "kroupa milgrom". Consider 3 hypotheses: (1) Milgrom's MOND has many empirical successes. (2) The empirical successes of MOND require a new paradigm for the foundations of physics. (3) The new paradigm must be either string theory with the infinite nature hypothesis or string theory with the finite nature hypothesis. Does string theory with the infinite nature hypothesis suggest that Heisenberg's uncertainty principle needs to be replaced by a new uncertainty principle which incorporates both Planck's constant and the string length? Does string theory with the finite nature hypothesis suggest that Heisenberg's uncertainty principle never fails, but the fundamental basis of nature is an Einstein-Riofrio duality principle in which quantum information reduces to Fredkin-Wolfram information? Consider hypotheses (A), (B), & (C): (A) Gravitational energy-density is bounded away from zero. (B) During each Planck-time interval, the gravitational energy of our universe decreases by precisely one unit of Fredkin-Wolfram energy. (C) The wavelength of a fundamental particle is always an integral multiple of one unit of Fredkin-Wolfram energy. Have the string theorists underestimated Milgrom? Have the string theorists underestimated Riofrio, Fredkin, and Wolfram? Is the problem that I fail to understand physics?

  56. Röda Pringles

    Maybe we are the first intelligent life to ever exist?

  57. Lamar Clintn

    NO !!!

  58. Doldol D

    Really interesting episode


    Very interesting, thanks! P. S I'm musician, doing some space electronic music. Have some interesting stuff on the channel 😌🖤 Thanks for the attention

  60. Miracetti

    "QLG is bs. Its nothing compared to that mighty phylosophical building that is string "theory". O'Dowd, Matt

  61. Anron Jatu

    This is the idea that liberals push. They can make a machine that uses less energy to create energy thsn it takes to create. Thats whynwe dont have solat powered airplanes

  62. frysebox1

    Me: Officer, why am I being detained? Officer: 2:18

  63. Laurisa718

    I'm too stupid for this, but I'll contribute anyway. I might learn something!!!

  64. Bradislav Gorlamski

    You think this guy is smart??? Babble babble babble babble babble babble babble babble babble. That's not even science. That's the stuppidest thing I've ever seen. And this is considered to be knowledge! Geeeeeeeeeesus!

  65. salg

    Is climate change separate issue or could the two be related?

  66. Anshul Tiwari

    Schrodinger's equation is actually 'so danger' equation

  67. Daniel Patjanan

    how do we even know its a rock the are no pictures made of it. They only could see that it reflects sunlight and how it shaped and that it tumbles

  68. Zanoth Verin

    I already assumed all of this.

  69. john nordqvist

    I hope there some really high person out there who watched this and now is trying to construct a gecko quantum reactor. Damn reptiles and their quantum secrets.

  70. superbura9

    You look like a nincompoop and sound like a muppet, you f*cking aussie. God, I hate your bloody aussie accent, you bearded muppet. I couldn't complete this silly video. 1 out of 10.

  71. Zshjohn Clark

    Hey Spacetime, where is the follow up to this video?

  72. Fubnin

    Seems like there's infinite variations on how to say 'i don't get it' too. That's great pal.

  73. John Wood

    Why the weird newagy music? Is it supposed to make it more... X-Files?

  74. xarmanhs h

    how does that work with infinite inflation?

  75. outlaw71

    What about voyager 1 and 2 they will travel through space for millions and millions of years faster than a bullet with only the initial inertia propelling them. That is close enough for me.

  76. Patrick Fitzpatrick

    I wonder if going forward in time they absord/(and/or) eminate different energies then when going backward....I imagine it innately adapts to traveling either way..or any direction.. in space it deposited evidence in 3 location along the same time.....they are in different locations...and then it move back in its direction...... There may be differentials in the location in the the direction changed.... I'd also imagine they are

  77. Calton Ramseur

    This makes me feel like Gucci mane in 2006

  78. CharlesDourdy

    Did he say that something with a half-life of 100 years is *safer* than one with 200 thousand years? If so, that's very backwards.

  79. Bluegrass Diggers

    The amount of carbon we emit is likely to offset an ice age

  80. David O'Banion

    However ferventy we may seek answers about the workings of space-time, there is no requirement that it reveal its secrets to us. In other words, we may be a product of nature, but we may never be allowed to learn all the facts about it. We should keep trying, though.

  81. zephiro l

    it's boring and god awful, kinda like the narrator here.

  82. jeeshadow

    "this is an unthinkably small probability, but not a 0 probability." So you're telling me there's a chance! :D It's so egocentric back when the going theory was that earth was the center of the universe. Current theory is there's millions and millions of versions of me. (silly humans)

  83. J.M .B

    I think we should terraform earth instead, forget about Mars.

  84. Lance Tschirhart

    Great apes _are_ monkeys. Jesus Christ, these cosmologists..

  85. adrienne gellman

    If you search USsel for Jim Al-Khalili The Double Slit Experiment you'll find a video where Jim Al-Khalili talks about a version of The Double Slit Experiment that scientists did where they left the detectors in the experiment,turned them off and then left the scene.When they returned they found an interference pattern on the screen at the back of the experiment.This proves that the presence of the detectors alone DIDN'T interact with the wave function,cause decoherence and cause the collapse of the wave function.Someone has to LOOK through the detectors or the wave function DOESN'T collapse.Also it proves that atoms KNOW when we're looking at them and when we're NOT looking at them.

  86. S


  87. Manu V

    Do I come here just to feel dumb!?

  88. James Flanagan

    No way the big bang created the universe.Energy never organizes itself.Energy without intellegience is chaos.No way it organized itself.Thats never been seen or observed ever!!!

    1. p v

      The big bang didn't create the universe. The big bang is the universe expending.

  89. S

    It can't break anything. It doesn't exist.

  90. niZSht561

    The lisp, is strong with this one!

  91. S

    Neutron stars are a mathemagical fantasy. Call me when you find something weighing 10 million tons a teaspoon. I'll give you 10 million dollars.

  92. ҉


  93. German Rojas

    Colonize univers cuuh.. we should me outside world restaurants...

  94. David Burton

    It wasn't long ago that I left a comment on the Big Bang theory, that it never happened and now suddenly my feed includes more concerning this idea which is totally bunk. It reminds me of the times I bothered to comment unfavorably about the Flat Earth theory which is of course total bunk. So anyway, why exactly is it so important to convince you or me about any of these theories? I guarantee you that there is some AI wizardry behind it. But none of that would exist if it weren't for somebody paying for it. You haven't already been convinced of anything that someone else didn't pay good money to make sure a plurality of society agreed with certain theories without bothering to subject claims, data, the works to proper, clean, bare logic. Also notice that you are constantly fed a bunch of stories that are never followed through by further positive action because that wasn't the point. The distraction was. Likewise with Big Bang, Flat Earth, hollow Earth, climate change and evolution. It's all intended to distract you from dealing with the basic facts of your own individual lives. They want you to blame yourselves for what they are responsible for and guilty of. But they have something you don't, ownership of and control over all the money. That's what THEY are distracting you from recognizing, otherwise you might just decide to do something unexpected by them, like owning and issuing your own money. So we need our own money : Please read the blog thoroughly and get back to me. Thanks and best

  95. Art

    Had to downvote after the first two seconds :(

  96. Raven_of_ZoSo

    Some people likes to watch cartoons when being high, me, I like watching stuff about space. If I became a full time stoner I could probably get me a degree in astrophysics.

  97. lasso atrain

    It's because they are multiply the speed of light squared . You can't square a circle.

  98. Jacob Forahee

    God will destroy the earth with fire. That's why we must repent and come to Jesus now.

  99. Jason Richardson

    What is the universe expanding into if not space.

  100. Yewbzee

    Sad to say that the only thing I actually understood in this video was the wingardium leviousa reference. Why am I so dumb?