Dec 12 2011

Stray thoughts

This just popped into my head and I wasn’t quite sure what to do with it, so I decided to just post it as-is.

Q: Why does time only flow forwards and not backwards?

A: Some time does flow backwards, but since its point of origin is also the big bang, we can’t see it because it’s headed the other direction.

(I have no reason to believe this is true. Or false.)



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  1. 1

    it is actually a good question. check out cosmicvariance.com for related stuff. here is a link to start you out:


  2. 2
    Yellow Thursday

    Interesting question. Here’s a few more that may or may not have answers: What does it mean for time to flow backwards, and would we even recognize if it did?

  3. 3
    Daniel Schealler

    Q: Why does time only flow forwards and not backwards?

    A: Time is lazy. It only ever wants to go downhill.

    (yes, I am being facetious – but on the off chance this turns out to be a workable metaphor for an actual theory regarding the arrow of time I will slap a physicist somewhere)

  4. 4

    As mark Twain would have said, “It’s too many for me!” I just know the guy in the mirror doesn’t look like he used to.

  5. 5

    And what if they loop around and meet on the other side, and that’s what causes(d) the big bang?

  6. 6

    Think how we’d process our food if time flowed backwards!

  7. 7
    Tige Gibson

    Time does not flow. Time is static.

    In system theory, you can reverse causality using recorded data, but natural systems are unpredictable at a quantum level, which means if time could go backwards, it would not reverse the same way that led to the point where you turned time back, leading to nonsensical paradoxes.

    If you were to go back in time to 300BCE and immediately come back the entire world would be permanently altered in extreme ways, not due to butterfly effect, but simple randomness accumulated over the vast time period, even if you did absolutely nothing in the past.

    There are not multiple parallel timelines. People only assume that such timelines diverge at “choices” but neglect every possible instance in which something could have happened but didn’t. In other words, there would be new universe branches for every Planck time at every point in space. Such conjectures serve no purpose except to support some fantasy.

  8. 8


    If you were to go back in time to 300BCE and immediately come back the entire world would be permanently altered in extreme ways

    You sound pretty sure about that :)

  9. 9
    Irreverend Bastard

    Time does flow backwards, as well as forwards. But we can’t remember it. Our minds don’t work in reverse.

  10. 10
    Ray Moscow

    On the subatomic scale, time works in both directions.

    On the macro scale, it doesn’t seem to work the same way, perhaps because of entropy. Sean Carroll and other physicists have written on the topic: http://preposterousuniverse.com/eternitytohere/

  11. 11

    @3: I have seen physics summarised thus: “Relativity says matter is lazy and always follows the shortest path. Quantum theory says matter is stupid and tries all the other paths as well.”

    1. 11.1
      Daniel Schealler

      FSM damn it.

      Poe’s law applies to physics now.

  12. 12

    time flows which ever way Chuck Norris wants it to flow. ha!

  13. 13
    Tony Hoffman

    Sometimes I wonder about things like “the speed of gravity.” In other words, if you could introduce something with mass one light year away, would the effect of that object’s mass reach you before light emitted from the object at the same time?

    1. 13.1

      It has been known for some time now that gravity propagates at the speed of light. That is to say, using your example, the mass would be detectable one year from it’s appearance, relative to its own timeframe.

  14. 14

    The past and the future do exist right now – that’s the point of “spacetime”. Just as locations in space exist even though you aren’t in them, points in time exist even though you aren’t right now concious of being in them. Your question really has two parts. 1) why is there an arrow of time? As someone pointed out, that arrow doesn’t seem to be required on the quantum level, so why do we seem to perceive time as moving forward? The best answer seems to be that entropy requires the time arrow. 2) the second question is perhaps best described by Vonnegut’s wonderful speculation on time in Slaughterhouse-5, with the Tralfamadorians who “see” all of time simultaneously, & Billy Pilgrim, who becomes “unstuck in time” and jumps around in his own lifetime. Why can’t we do that? The best answer I can give you is that the 5-year old Deacon and the 25-year old Deacon are still there and still conscious of time, but we aren’t Tralfamodorians. We can’t perceive more than one instant. Late in life, Einstein referenced this very idea, saying as a good physicist that he preferred the continued existence of his life in that the past over the idea of an afterlife (that’s a very rough paraphrase).

    1. 14.1
      Daniel Schealler

      Another point to consider is that the inner sense of continuous identity we have is an illusion – so the 5 year old ‘Daniel Schealler’ and the 27 year old ‘Daniel Schealler’ are seperate entities that are only related by constructed memory and narrative. Not physics.

      So perhaps we’re all Tralfamadorians – but we each only exist for an instant, only to be replaced by a new Tralfamadorian in the next moment.

      Just a thought, see. ^_^

      1. jakc

        that explains the strategies of Mitt & Newt in the Republican primaries: “See, it was a different Mitt/Newt who did that. I’m not at all responsible for those actions/views”

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