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. Mark Bondurant

    Coal power accidents don't cut unusable holes in the map. (just sayin')

  2. exitolaboral

    Past and future seem to be just configurations of the available mass / energy. These configurations change according to the known physic laws. Each of the "slices" in time are just configurations of the available mass/ energy. And time is a local phenomena. Einstein says so. There is no "universal time" for the whole universe. The whole idea of "existing past" or "existing future" universes goes against all current know physical laws.

  3. Yannick Wolfe

    That video really didn't convinced me that Venus is a better option. But it seems I knew all that since high school.

  4. cz1mmt

    We create our own reality. I once dabbled in witchcraft. One exercise was to place a black dot in the middle of a blank sheet of paper and move it around at will. I quickly discovered I could do it. I also quickly realized I didn't really move the dot, but my reality of the dot. Never did it again.

  5. Zyzz

    I really like this channel but I don’t think I have the mental capacity to understand it completely.

  6. M Al

    Newtons law of gravity is ONLY 60%..on earth..40%is EARTHS SPINNING WICH CREATES.. A FORCE THAT want TO push US off THIS PLANET.. Bhot KEEPING US in BALANCE AROUND 1g....🙏🏽🙏🏽🙏🏽GR KARMA

  7. Wysent Pyrrhus

    What was that about the ruler behaving differently in zero g?

  8. exitolaboral

    Quantum mechanics seems to presupose mass / energy conservation. Having a multiverse goes against mass / energy conservation. If each event generates an infinite number of posible universes, there is no conservation. In fact we could use this phenomenom to generate electricity!!!!! Could be a cheap way yo get free energy!!! Climate Change solved for good!

  9. M Al

    ITS WEAK AGAINST small👈.. AND very STRONG AGAINST big... 👈🙏🏽

  10. M Al


  11. Ardulca Silvara

    Stop trying to sound British to get followers, it was cool 60 years ago when it was rare to hear in USA. Now knowing that you are acting, it gives me goose bumps. Normally I shouldn't get bothered but I guess because you are all faking an environment, it gets more of my judgmental side out, so 2 more evolutionary feedback for you to get more money ehm I meant "your beloved followers" 1) work on those shoulders and chest 20 mins a week, if u do 2 push ups a year you'd have a proper size of chest so you wouldn't look like you are coming from 2068 with a useless android body and a large thinking head. 2) loose that button on your shirt. On top of all this, it makes it way too clear that you are TRYING to be accepted by your donators to make that money by getting moooore viewers.

  12. Shazistic

    Impossible is just an opinion. -Shazistic

  13. Shazistic

    Sometimes you must hurt in order to know, fall in order to grow, lose in order to gain, because life's greatest lessons are learnt through Pain -Shazistic

  14. Shazistic

    Sometimes you must hurt in order to know, fall in order to grow, lose in order to gain, because life's greatest lessons are learnt through Pain -Shazistic

  15. Shazistic

    Sometimes you must hurt in order to know, fall in order to grow, lose in order to gain, because life's greatest lessons are learnt through pain -Shazistic

  16. Shazistic

    Sometimes you must hurt in order to know, fall in order to grow, lose in order to gain, because life's greatest lessons are learnt through Pain -Shazistic

  17. Shazistic

    Sometimes you must hurt in order to know, fall in order to grow, lose in order to gain, because life's greatest lessons are learnt through pain -Shazistic

  18. Shazistic

    Sometimes you must hurt in order to know, fall in order to grow, lose in order to gain, because life's greatest lessons are learnt through Pain -Shazistic

  19. Shazistic

    Sometimes you must hurt in order to know, fall in order to grow, lose in order to gain, because life's greatest lessons are learnt through Pain -Shazistic

  20. Shazistic

    Sometimes you must hurt in order to know, fall in order to grow, lose in order to gain, because life's greatest lessons are learnt through pain -Shazistic

  21. Mr Magooo

    I just wanna know how to win the lottery

  22. DaRkPhAnToM

    Dirac looks like Howard stark

  23. Marvin Edwards

    Stuff moves. Where it was earlier is the past. Where it is now is the present. Where it will be soon is the future. This is the case regardless of our observations. Time is not a block in empirical reality.

  24. Jim Doe


  25. Travel Services

    I've always thought that, once formed, black holes should grow at an increased rate because they can actually grow by absorption of dark matter (whatever that is), unless it can violate General Relativity, which seems unlikely. Dark matter may not interact with "ordinary" matter in any "ordinary" way, but it appears to interact gravitationally, so I can't see it (ha) escaping any event horizon. So black holes should all be bigger than one would expect if they were formed just from ordinary matter. But I've not yet heard or seen or read anything that deals with this specifically. I don't know whether that might influence the tight lockstep between supermassive black hole mass and the mass of their galaxies, since the galaxies' mass is, usually, dominated by dark matter (again, whatever that is).

  26. kayakutah

    The balloon doesn't move. It's at the end of this video... I had a helium balloon in the van and was driving home for my kid's birthday. As I made turn to the left, the balloon moved to the inside of the turn - to the left. Really surprising at first. The heavier air around it was pushed to the outside of the turn and the balloon "floated" to the inside of the turn.

  27. John Smith

    Since dt is really d(planck time), do I need to redo all my time dynamic quantum equations with that? WTF.

  28. De Nostrechat Jacques

    words added to words, if equation fail: you had something that make it work even if you cant prove it beside using the math you invented :) to resume: if giraffes where green, they will poop bananas.

  29. Douglas Smith

    Idea for future episode: What if the speed of light is variable over time? I would be interested in an overview of the various VSL theories, and if any of them can be taken seriously. See:

  30. Bruce on the Loose

    My brain hurts, maybe it’s decoherence.

  31. itzybitzyspyder tv

    *short answer:* Yes. *long answer:* Yeeeeeees.

  32. Jake Coasters

    Scientists: We believe there could be life on Venus *Holds up picture of a Waffle House on Venus* Government: My God

  33. Antonio Renteria

    Anything starting from a singularity has to be completely random. Because there are no variables to begin with to make any kind of determination.

  34. Horace Lastname

    When showing the Petit et al graph, why not plot them on the same axes? We could then see that temperature changes have always preceded CO2 changes, and temperature has many times fallen whilst CO2 was still elevated, ie CO2 does not drive temperature - rather the reverse, via change in solubility of CO2 in oceans, as you mentioned. I enjoyed the objectivity of this video up until: "Modelling climate is a huge challenge, but don't mistake that for a lack of certainty [What!]. Our influence is certainly enormous....... Venus." Why end on illogicality and mindless alarmism? Stick to science. Leave Greenpeace something to do.

  35. joshua abbott

    Aliens are already here

  36. Jean Corriveau

    Since there's an infinite number of universes, then there's a copy of me in at least some of them. Since consciousness is created by the brain, then it isn't me just like twins aren't the same person.

  37. Greg King

    The past should not be considered different to the future. Predicting the future or remembering the past are both dependent on "time". Quantum theory strangely focuses on time being only in the forward direction and that the past is somehow known thru experience. Is it not possible that a time slice in the block universe also creates the time slices behind it. Our past is manifest in the same way our present and future is. The terms "Quantum uncertainty", "timeless" and "remember", surely can't be associated together in a meaningful statement on this subject.

  38. The Blue Phoenix: Captain Gamer

    6v53 Found it! Without even trying lol

  39. Alexey Mightle

    Future is predetermined BUT there is a paradox - if someone finds out their Future or starts to think about their future predetermination then paradox of Choice kicks in. Whoever reads my comment and truly want to know text me and I will explain it in detail and examples!

  40. Rebecca S

    The penrose diagram is my favourite recurring character on space time. After seeing it on at least 3 episodes so far, I'm understanding it better each time :D

  41. 1337fraggzb00N

    There is no life on Venus, I looked twice.

  42. Jean Corriveau

    The Theory of relativity is based on light having the same velocity regardless of frames. So, this theory doesn't apply at the moment of the Big Bang since light, electromagnetic, didn't exist yet. Should physicists believe that time existed at the Big Bang or before that light emerged, then they have to change the definition of time. Time should be the time it takes for causality.

  43. Shawn Drumm

    A&E for 911 truth is challenging NIST at this time and winning. They are cowards

  44. jokerclownpince

    Man iv had dreams months of me going through a day . And then the day comes and its Daja Vu and u remember the dream and how real it was and then I wonder if I have control of what is going on. Then I look up at the stars and fall in love with everything

  45. john mark pampolina

    Does a blackhole have a rift . If it have a rift , how possible is that to happen ? . 🤔🤔🤔

  46. GodsPorter

    Many worlds is absurd . The wave function of reality is most definitely I not determined . God observes every version of you before you yourself makes a decision or “collapses the wave function” . Those other versions do cease to exist but they only seemed real in so much the fact that you “had” the “opportunity”/probability to become any one of those versions of you . The sovereign will our independent conscious, we inherit from God makes it so that version is undetermined . We ourselves choose . The thing that makes it seem determined is the fact that God knows what you will choose, as he is the multidimensional entity that sits outside of all spaces and times . He is the ultimate observer. We are tiny observers .

  47. carl gangl


  48. Balendula

    I wonder if these other universes are visible via the 5th dimension or higher.

  49. Andrey Lebedenko

    The children of light can see as "now" only what they can see now.

  50. Blake Thompson-Dodd

    'Wen considered the nature of time and understood that the universe is, instant by instant, recreated anew. Therefore, he understood, there is in truth no past, only a memory of the past. Blink your eyes, and the world you see next did not exist when you closed them. Therefore, he said, the only appropriate state of the mind is surprise. The only appropriate state of the heart is joy. The sky you see now, you have never seen before. The perfect moment is now. Be glad of it.' - Terry Pratchett

  51. Clap Trap

    So maybe the big bag wasn't a creation event. Everything already existed. The big bag just kicked off time.

  52. Steve

    You guys have a lot of imagination.. its not a hole.

  53. Garethaxz

    TLDR: Yes, but also not really or completely. But absolutely in a way which is both consequential and inconsequential and may or may not ever be measurable or observable/relevant except when it is (which is mostly at a smaller scale). At the smallest scales and experiments the outcomes are nearly 100% predictable and our ability to predict or anticipate the outcome of more and more complex interactions has been growing exponentially. Eventually, since the universe is of "constant Mass/Energy", it would feasibly be possible to predict all outcomes by simply understanding the outcomes of infinitely-many, infinitely-smaller, controlled and predictable reactions. This is essentially "Laplace's Demon" and whether or not it is accurate is near-universally met with a resounding "maybe, but it doesn't matter". At the end of the day, compatibilism is likely the best you can hope for and being aware of it may or may not change outcomes in your life, but it likely didn't matter because other pre-existing stimuli and environmental conditions meant you'd have been exposed to it and felt the same way about it, at about this time, provided all pre-existing events were the same.

  54. AI fan

    I can't think of a mechanism whereby a white hole could come into existence within our universe but if it did I would expect it to be at least as black as any black hole since everything within would be ejected very rapidly, and thereafter there would be nothing to eject and nothing can ever enter that region of space. Perhaps such a thing would still be subject to Hawking radiation though.

  55. Michel Engelen

    events influence time and time influences events. What is the speed of time? has it a max and minima ? would we be able to tell /measure if time stood still? The big bang was possibly an event in the equilibrium of Time Time Governs what we call Gravity, Gravity as such does not exist -> that's why we will never find it as Gravity but only in the weirdness of Time and it's relativistic character.

  56. Breaking Bald

    you're using too much QUOTE SINGS it's Distracting

  57. Chad Judd

    Why don't you ask Trumplican this question.....F=-F

  58. Alex Brain

    Relativity is wrong, quantum world is the base!!


    This bugger doesn't know what he is talking about. Deterministic future; past, present and future all contained in the very moment of existence? Drawing in Einstein's relativity and time dilation to expolate? Don't upload such rotten videos again.

  60. teapotdome

    Learn to swim.

  61. hcm9999

    The Fermi paradox is based on the assumption that advanced civilizations use vast amounts of energy, enough to be visible from Earth. But that assumption may not be true. An advanced civilization most certainly has not only low mortality rate, but also low birth rate, which results in a stable population and a sustainable society in a planet with finite resources. In such conditions there is no need to colonize other stars, or even other planets. With a small, stable population, sustainable society and plenty of resources, their only goal would be to make their lives better and more comfortable. No need for an interstellar or even an interplanetary colonization. At most they would just send robotic probes to other stars for scientific curiosity. And because their energy comsumption would be small, they would not be visible from Earth. The assumption that advanced civilizations inevitably develop into interplanetary or interstellar civilizations is most certainly false. Any civilization that grows exponentially is doomed to extinction since such a growth is not sustainable.

  62. DavidisGoliath

    HA CAve MEN! The Future is not predetermined by Quantum Mechanics its determined by our actions duh, what are theres hippi's smoking?

  63. ganerdene uurtsaih

    Okay when are we going to check it out?!

  64. The Way

    There's no time, man.

  65. Mevine Ven

    They haven't go far even to 3rd planet of our solar system yet talking about multiuniverse what a kind of dump science we have

  66. brightorb1

    everything was fine and clear until 2:44 when he introduced the laser and the monkey . I got completely lost

  67. Oliver van der Togt

    There is no 'now'. Everything is spread out between the past and the future. As when a group of people start walking and they spread out between the fast and the slow walkers. Where is the 'group'? They have evolved from a particle/group to a wave/line of walkers. What we observer as the wavefunction could be considered a further spreading out between past and future.

  68. Lee Mawdsley

    Spaceology is real

  69. Pinky

    I'm stuck on the idea that there could be other observers collapsing the wave function in my space before I do, where my present is their past. Doesn't that idea defy the locality of time? How could they be local enough to observe but in a time frame ahead of me at the same time? My understanding is that the present is the defined state of all the universe and time is a gradient effect of potential working to resolve the indeterminate future locally, at different rates. Add in quantum superpositions and observers collapsing the wave function shouldn't complicate that model... but adding local observers in another time frame just sounds like a spacetime paradox or just a misconception of spacetime to me. And how can the quantum wave function collapse to organize consciousness without being observed by an outside consciousness? Doesn't the entire concept suggest a universal consciousness or God? If quantum mechanics requires that an observer collapses the wave function to determine the form of the universe, the fact that we can observe the form of the universe and this quantum wave function means pretty conclusively that the future is at least partly determined by a God that observed us to be observers, and that we still have some opportunity to observe and determine for ourselves.

  70. Nuno Hipólito

    Got it

  71. husnain ali

    Lmao the intro is quintuplet swing Science channels use complex rhythmic devices This is ironic and funny pls laugh

  72. Andres Figari

    I so love this channel but I don't understand 90% of it...

  73. Brent Bay

    this is the first time i've felt genuinely confused, can't wait to sleep on this for a few months or years. Space built out of closed loops of varying shapes? seems to appeal to my senses though

  74. Expod

    Because of chaotic systems, my initial answer was no. But now I see "by quantum physics" and I'm interested.

  75. Pelorix

    Logic is still waiting for science to catch up.

  76. arrowsplit

    It's always the same with PBS Space Time videos. I understand the question. Not the answer.

  77. Mark Solis

    So all we got out of the LHC project was only one lousy little new particle?