Did Time Start at the Big Bang?

  • Published on Jul 18, 2019
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    Our universe started with the big bang. But only for the right definition of “our universe”. And of “started” for that matter. In fact, probably the Big Bang is nothing like what you were taught.
    A hundred years ago we discovered the beginning of the universe. Observations of the retreating galaxies by Edwin Hubble and Vesto Slipher, combined with Einstein’s then-brand-new general theory of relativity, revealed that our universe is expanding. And if we reverse that expansion far enough - mathematically, purely according to Einstein’s equations, it seems inevitable that all space and mass and energy should once have been compacted into an infinitesimally small point - a singularity. It’s often said that the universe started with this singularity, and the Big Bang is thought of as the explosive expansion that followed. And before the Big Bang singularity? Well, they say there was no “before”, because time and space simply didn’t exist. If you think you’ve managed to get your head around that bizarre notion then I have bad news. That picture is wrong. At least, according to pretty much every serious physicist who studies the subject. The good news is that the truth is way cooler, at least as far as we understand it.

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Comments • 4 570

  • George Jacob
    George Jacob 4 hours ago +1

    One day humanity will laugh at our concept of time

  • Brendon-Kayne Albertze
    Brendon-Kayne Albertze 16 hours ago

    "certain crowd"?

  • Dichtsau
    Dichtsau Day ago

    i believe since a long time that we're inside of a black hole, but i'm curious if any1 else ever thought that this also means we're existing reverse through time, because a big bang fed by an outerdimensional black hole would have to spit out everything the black hole swallows before it did do so - unless my idea which i based on ancient myths is true and the big bang is still ongoing! :)

  • Maulik Bagada
    Maulik Bagada Day ago

    Am I on lsd?

  • Marcelo Di Cocco

    Excellent, very didactic explanation. thanks!

  • Arthur Daily
    Arthur Daily Day ago

    You been working out that left arm? 💪. T shirt is hanging off you bro

    RAYEN G'T Day ago


  • Dolly Dupee
    Dolly Dupee 2 days ago

    If the Big Bang happened in 1 km in diameter. The only way space can continue to grow is by micro nutritions were there in space to feed and grow. To grow from nothing is not probable.
    Pre Big Bang time exist maybe not for us but for someone. Peri and post Big Bang time exist for us.

  • inox1ck
    inox1ck 2 days ago +1

    If time and the Universe starts at the Big Bang there is no notion of before the Big Bang. There is no universal clock according to relativity, otherwise you could go back anywhere in time in principle and time before BB would make sense. So that way infinities which cannot be explained are not necessary.
    This is not something from nothing because there is no moment in time where there was nothing

  • wood1155
    wood1155 2 days ago

    I can't watch this guy

  • T K
    T K 2 days ago

    Geodesic incompleteness is the most satisfying answer to the logical mindfuck that is the question of time having a beginning. And yet, you take it away from me.

    • inox1ck
      inox1ck 2 days ago

      T K it is the only way you don’t need infinities anymore, which can’t be explained. Relativity is against a master clock. The theory is not a complete theory but it doesn’t mean it gives an answer far from reality.

  • Stéphane Blouin
    Stéphane Blouin 3 days ago

    The problem is that they're assuming T=0 means where time starts. That is not where time starts, but the moment the expansion started. The T variable is not so much a measure of time for say, but of time during the expansion. T=0 being the moment a singularity occurred, the initial moment/time where expansion begins but space/time already existed.

  • Tomas Molina
    Tomas Molina 3 days ago

    Am I the only donkey that takes like 40mins to watch each video?

  • kn1102
    kn1102 3 days ago

    Did time start at the big bang..... I will say yes if you see time as AD or BC. Now if we are talking of a universe no.
    By the galactic term I would say it never started or has an end , but is a free flowing recycling event + -

    • kn1102
      kn1102 3 days ago

      Now if you could think of an hour glass at the center there is a small space where every thing is put in one spot it will all go one way in the other way like looking in a mirror. So this would apply bouncing from one verce to one more

  • Philippe durrer
    Philippe durrer 4 days ago

    cool explanation with the geodesics, learned something new :)

  • Topsy Turvy
    Topsy Turvy 4 days ago +1

    [: (0-0=∞) (∞-∞=0 :] it's all an eternal CAUSE-EFFECT cycle."WHY?", Why not, dearSocrates? Let's forget about the OBSOLETE logics of ENDOCTRINATION & ACADEMIZATION.

  • Antonio Carranza
    Antonio Carranza 4 days ago

    4:23 I'm tripping out!!!! This video has put me on an Acid Induced state and I have never taste that stuff.


    Is the expansion in space-time directly linked to the “forward” motion of time?
    Would time “revert” should space-time contract and is that why time runs “slower” near super-dense bodies?

  • The Whiz Kid
    The Whiz Kid 4 days ago

    That would be the Big Bang theory, but it is possible to think of negative time. In the early universe, there was a war of sorts between matter and antimatter.
    Matter won, so we live in an universe which is composed of matter.

  • Nudedragon
    Nudedragon 4 days ago

    I know you get a lot of comments saying people are lost, and for sure I'd have a lot of homework to fully understand, but you do a great job making this stuff accessible imo. It's really complex and it's still understandable enough for me to take some information out of each episode that makes sense

  • SomeGuy
    SomeGuy 4 days ago

    His uneven shirt ruined this video for me.

  • Adrian Flatley
    Adrian Flatley 4 days ago

    When did you start these ads??

  • Blue
    Blue 4 days ago

    Great channel and stuff, great topics... but your voice gets a little boring after some time watching you. IMO there can be a little improvement on that. I dont expect you talk like a twitch streamer, but some tricks and techniques can help you out with your view count (I think).

  • Ian Foote
    Ian Foote 4 days ago

    But, the universe ISN'T infinite. It has an edge. So, why do you keep talking about the "infinite universe" over and over when it's not?

  • Vindignatio
    Vindignatio 4 days ago

    what dat music at the end, i like

  • Man Jay
    Man Jay 4 days ago

    Q: Did Time Start at the Big Bang? A: No. Why? Because obviously, there was a "time" before Time. When was that? Well, it was the time before Time started.

  • Robert McMurry
    Robert McMurry 4 days ago

    What is the music playing at the end of this episode during the Last-pass sponsor announcement?

  • tabaks
    tabaks 5 days ago

    Question like this implies we know the nature of time, it even implies time exists. I don't think we're there yet!

    • tabaks
      tabaks 4 days ago

      Hmmm, that's just old thinking. Maybe time is just a theoretical derived measure of energy and wave propagation. "This wave took 20 oscillations of this other wave to propagate from here to there..."

    • Tony Mangaka
      Tony Mangaka 5 days ago

      Time clearly does exist, it takes X time to get from point A to B, that's why we refer to this dimension as 'SpaceTime'. You'd be teleporting everywhere at will otherwise, but implications are way worse, age, your existence, current state of everything as we know it just wouldn't be.

  • john hanrahan
    john hanrahan 6 days ago +1

    How can any action take place without time?
    Was the lack of time the constraint which kept the singularity intact?

  • Apaulo Thegreat
    Apaulo Thegreat 6 days ago +2

    Time began the time God created read my lips

  • patriotgregory
    patriotgregory 7 days ago +1

    Is it possible that math and the laws of physics that govern our known Universe become obsolete at both the Macro and the Micro levels?

  • Aadhitya Sriram
    Aadhitya Sriram 7 days ago +1

    Hey I have a doubt if there was only a infinitely small point what was around it

    • Abe Kane
      Abe Kane 2 days ago

      @Aadhitya Sriram No problem. It's a question I've thought about a lot and it always good to find people curious about the same things

    • Aadhitya Sriram
      Aadhitya Sriram 3 days ago +1

      @Abe Kane dude thanks for taking the time to explain, that I really appreciate. Thank you.

    • Abe Kane
      Abe Kane 3 days ago

      That's a question what can't (yet) know the answer to. Some people speculate there is other universes, but I like to imagine it is a anti-temperospatial negative energy void and our universe is it's opposite, a bubble of positive energy/mass with existing time-space, that the vacuum outside is trying to tear apart, causing our bubble to expand until it pops and returns to the void

  • mert gökgöz
    mert gökgöz 7 days ago +1

    5:28 mentioned singularity is different then what is inside a black hole? Or are they literally the same thing? I assume not but just curious

  • Keshava Reddy
    Keshava Reddy 8 days ago

    I was lost at 3:53

  • Kory Toombs
    Kory Toombs 8 days ago +1

    If time is relevant to the mass of an abject then time was irrelevant before the big bang.
    This means that time acted chaotically or didn't exist.
    Chaos Time is the best.

  • Sawyer West
    Sawyer West 11 days ago

    If time slows down when gravity increases, shouldn’t it be the case that no clock from any observer in the universe could be rewinded far enough to reach T = 0?

    • Sawyer West
      Sawyer West 11 days ago

      A follow up question: how would this adjusting ‘speed of time’ scale the time geodesic @7:24 as the graph shows earlier and earlier time periods?

  • Physics Ghost.
    Physics Ghost. 11 days ago

    Einstein's theory of Relativity says that time flows at different rates everywhere. Therefore the big bang theory where time is traced back to a single point in the past is a misconception.

  • JINXtheGamer
    JINXtheGamer 12 days ago

    It wouldn't surprise me if TBB didn't create time-space but instead expanded in preexisting time-space.

  • Worldwar2 Lucky
    Worldwar2 Lucky 13 days ago

    And did you know all electrons have the same and energy, all exactly identical, all the way up to the Google number

  • ajit thakali
    ajit thakali 14 days ago

    to big bang to happen time is required...time was there before nothingness as well

  • BumOn TheCorner
    BumOn TheCorner 14 days ago

    Living beings with an understanding of impermanence created time. Time is not a natural force there is no such thing as time. It is directly dictated by our sun. However there is timing and yes time and timing are different.

  • God Zilla
    God Zilla 15 days ago

    This deserves multiple viewings. I like the analogy of shrinking longitude lines!

  • Isaac Douglas
    Isaac Douglas 15 days ago

    No one: what if Feynman and hit German techno artist, Kraftwerk, made a collab?
    The creators of PBS Space Time: Say no more...

  • 5pecular
    5pecular 16 days ago +2

    What if there was no big bang. How do we know galaxies are not continually forming?

  • Jonathan Hall
    Jonathan Hall 16 days ago

    Yes. Matter, Space, and Time came into existence at the same time.

  • JJ Dwayne
    JJ Dwayne 16 days ago

    Parabola = observer ?

  • JJ Dwayne
    JJ Dwayne 16 days ago

    Time starts at 1st move. Something from nothing abstract / pre nature/pre- matter.
    Did God/creator take time to think about cubic space? dot Perpetual A to A x y + ?????????
    blueprint for Bang!????? Mind of Creator ??? im out.... my head hurts

  • Uday Kumar
    Uday Kumar 17 days ago

    If time depends on gravity. Then what is the time at the place where non-gravitational space?

  • Kyrlics
    Kyrlics 17 days ago

    Didn't watch the video but i don't believe time exist just because the big bang did. The universe was a singularity. It already existed. The big bang was simply the multi-dimensional expansion of it.
    There were things going on in that universe already. Quantum fluctuations and many other bizzare things that must be pretty hard to imagine, thats if we could even potentially imagine a small part of it.
    Time didn't exist because you, the egg and sperm popped into existence. Things were already happening way before you came in. Just like the big bang.

  • Lead slinger
    Lead slinger 17 days ago

    Brain candy lol. Fun thoughts all though with a large amount of unidentifiable matter and or forces It's hard to know exactly. More brain candy please😂😂👍.
    PS. Is it possible that dark matter is the medium that allows gravity waves to propagate through spacetime as well as explain the wave function in quantum mechanics?

  • Guy Lakeman
    Guy Lakeman 18 days ago

    photons do not perceive time ... when only photons exist time doesnt happen
    wen photons collide they create particles with mass, particles with mass experience time and wheer time begins

  • Robin Powell
    Robin Powell 19 days ago

    I don't understand, okay I get that general relativity does a poor job of explaining that time started at the big bang... but why should that mean it didn't? I mean, geocentricity does a poor job of explaining our day and night cycle, but that doesn't mean we don't have one!

  • dotdotgoal
    dotdotgoal 19 days ago

    I’m happy that I finally grasped some of what you said and I wasn’t entirely lost like in other videos. That being said it kind of makes me sad to wrap my head around the uncertainty of our existence. What are we? So meaningless to try to answer these questions it seems. I feel like I want to hear legends of old, maybe there’s already been answer to what we have been seeking for so long and it’s always been in front of us. That’s the narrative I want to hear

  • The 36 Lessons
    The 36 Lessons 19 days ago +2

    What if universes _reproduce_ similar to cellular mitosis, and each universe is a _cell_ comprising a metaversal _tissue_ or _brane_ ... and then what would they comprise? Infinitely similar, but infinitely different from _mother_ to _daughter_ verses. If fractal geometry is to be considered, it very well might be the case that the smallest structures within the universe may be repeated at the largest scales. A universe exising in an atom of a universe, infinitely repeating and expressed above and below.

  • DevInvest
    DevInvest 19 days ago

    Who’s time?

  • Tomek Kołodziejczuk
    Tomek Kołodziejczuk 20 days ago

    What is the song at the end?

  • Kev Gee
    Kev Gee 20 days ago

    Me at 2am after 10 beers... lets go on youtube and look at PBS.....

    Me at 5am after 15 more beers and loads of pbs videos and talking to my wife........

    2X2+3X3+Inifinity = my hangover tomorrow

  • bizo237
    bizo237 22 days ago

    A finite universe is not baby stuff, if it is a symmetric group. We can hope an exceedingly large universe is auxiliary to the formulation for an infinite one. Nonlinear finite structures may have tractable considerations, but physicists likes to assume modular forms, because they are exceedingly useful. Like most deep philosophical questions, it is best to let it come, let it be, let it go. A scarred drum may allow our linear considerations for how to map to a degree of freedom for translational invariance, but in truth, even string theory has interpretations, where symmetries are applied in a manner that is scaled to preserve the isotrometric of recursively enumerable geometry, on the cohomology interchange. We define operations, based on observable content, with priors of accident (those uninformative).
    Hooft tunneling can save some of these formulations, but the retort is cheeky, a sort of what information? Timeless the singularity would be for a determinism then. The big bang, one in the same with the p-branes, in which the universe is presently tunneling. A linear time. We do not need to decouple, when using a fermionic theory, but you could find yourself quite closed and needing shrinkage.
    We should leave GR to the masters. I would not say it is not a good description. I would say its interpretation, is more difficult. Emergent from QED, as gravity seems. Yet a monism of gravity, leaves us with many conundrums, when bringing a frame of reference, and requiring absolute clarity. Does gravity cause a state reduction, or could it bring completeness to special relativity, perhaps even making newton correct, not just as an approximation, from a decidably QM expression? The product space is interesting. Nature ever flirtatious with nothing.

    I would say for the purpose of this video you are correct. We can construct artifices, like retro causality, making an impact on the CMD, in some arrogant personal account, or we can have reverence for the ocean of ignorance, as we might have for a spin-tube middle-out formulation, residing beyond the visualization space. Physics ever the substrate conditional thesis. Memoryless the singularity would remain.
    And yet all manner of distortions are possible with a conifold transitions. Such a operation would be like using a spin network, as a bridge, to traverse distances impossible, a null geodesic, as stated by special relativity, still connected in a singular universe. Calabi-Yau once disconnected, and mirroring, as in Indra's Net, for the illusion of sameness, now leaning into gross distortions of configuration space, to once again express a sort of smoothness. Impossible preformed, via the seeding of completeness. Isotropic to the consistency of opacity. Phase of background, phase of the thermalization of time, or massless least action of a platonic nature? Complete, decided, consistent.

  • VITA kyo
    VITA kyo 22 days ago

    How can anything START ?

    • Hilmar Zonneveld
      Hilmar Zonneveld 21 day ago

      Not sure what you mean; you see things starting all the time.

  • Balsey Dean De Witt, Jr.

    No more singularity? I was always told it took 2 to Tango!

    • memberwhen
      memberwhen 21 day ago

      300 years ago people were taught that the sun revolves around the Earth, so that's not saying much tbh.