Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The past IS real?

  1. May 29, 2005 #1

    Ivan Seeking

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    When pressed for a definition regarding "the past", and whether or not it "does" exist, Brian Greene


    made this comment in an interview tonight.

    ~ I don't know if we can get there, but "the past is as real as the present"

    Interesting, I thought.
  2. jcsd
  3. May 29, 2005 #2

    Hi Ivan Seeking, and hello all.

    I've lurked here often, and found this site very interesting. I'm not a sceintist, though I can claim an enquiring mind.

    Regarding your post, I heard a quote once, which I thought interesting ... "The present is the futures past"

    What prompted me to register however, were the several quotes in your sig. I found them most refreshing, though unfortunately, often rebuked by scientists, even on these boards.

  4. May 29, 2005 #3
    The past is in the future and the future is in the past
  5. May 29, 2005 #4

    Steven Hawkings once asked why can we remeber the past but not the future.
  6. May 29, 2005 #5

    Ivan Seeking

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    What? People actually read those??? :biggrin:
  7. May 29, 2005 #6
    And why is this?
  8. May 29, 2005 #7
    We do not rememebr the future as we only experience the flwo of time in one direction - it is the same reason why we do not see broken tea cups fixing themselves and leaping up back on to tables.
  9. May 29, 2005 #8
    But why do we only experience the flow of time in one direction?

    Is there something stopping it from going the other way around?
  10. May 29, 2005 #9
    its the arrow of time. entropy always increases. so things always go from ordered to disordered. if a broken tea cup suddenly jumped up onto the table and mended itself, that'd be a more ordered state. therefore we never see it happen.
  11. May 29, 2005 #10
    Look up and see the night sky .....its the past.
  12. May 29, 2005 #11
    To elaborate on Gale's reply, the conclusion Hawking came to was that we will always experience time in the same direction that entropy increases because our brains become more ordered by creating disorder in the universe. He gives the example of a computer because we know how they work much more than brains. In order for a computer to "remember" something it has to write it to its harddrive, which takes energy. The amount of order lost in the universe from the energy needed for a computer to add something to memory is greater than the amount of order gained within the local system of the computer (to get energy for the computer we have to burn fossil fuels, etc)--therefore anytime you want to "order" something you must increase the total "disorder" of the universe as a whole by more. So for us to order our brains with new information, we have to use up energy and decrease the order of the universe as a whole, so we will always experience time in the same direction in which entropy increases.

    Hawking goes on to say that if entropy decreased as time moved on, and somehow intelligent beings were here to witness it, although they would hypothetically "see" everything happening in reverse (broken cups jumping back up on tables), they would remember the future and not the past. So when the cup was broken on the floor they would remember when it was on the table, but after it assembled and jumped onto the table, they wouldn't remember it having been on the floor; thus they would still be "experiencing" time in the opposite direction from that in which entropy decreases (ie: they will experience time just like us, as entropy increases, they'll remember more).
  13. May 31, 2005 #12
    There is no direction for the flow of time. There is no past, nor is there a future. What you may think of as the past is actually a current event. Whatever you may dwell on as the future is actually a current event. Without a past or future - there can be no flow of time in a particular direction.

    In our universe there are only ones, one at a time, where time is the nothing ones are composed of.
  14. May 31, 2005 #13
    This is not true at all. It should be categorized as your current state.
  15. May 31, 2005 #14
    Time moves in every direction. It is non linear. Its more like a bowl of Jello (pig tallow). If you have your wits about you you can look ahead, to the side and behind you, in the bowl of time, simultaneously. But the enormous amount of information about the future and all other directions in the time-jello-bowl requires a substantial amount of processing. The brain tries not to confuse its host organism with the details of how to get to the fridge or to the bar.

    Nor does the brain dilly dally the host with the infinite probabilities and actualities that are taking place, will take place or took place...... eventuating their arrival at the pub.

    Chain reactions don't just go from link to link, one at a time, all events are linked to one another. These links are also readily observable in what is today called linear time. But even more obvious are the simultaneous chain-reactions seen in quantum studies.
  16. Jun 1, 2005 #15
    You people are crack heads. Atoms move around, particles decay. Thats what creates the passage of time. Your brain only processes the information it recieves through the senses. It can't "see" ahead into the future.
  17. Jun 1, 2005 #16
    Is it true that if you make an atom go faster than the speed of light, you will really be going back in time?
  18. Jun 1, 2005 #17


    User Avatar

    That pretty much summarises it with the exception of "totallyclueless" wanting to know about "you will really be going back in time?" opposed to "ahead in the future". Still you're right, it's simply hopeless since we're unable to see, whether if it's in the past or future.

    All in all this topic intersperses a lot of time knowledge and an elaborate theory understanding about manipulative atoms fitting a required time space to permit an individual to "travel back and forwards in time. This is really inexorable, whatever you guys do, don't mention John Titor, a complete and total waste of time.
  19. Jun 1, 2005 #18

    Ivan Seeking

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    I don't think Brian Green and John Titor go together very well. :rolleyes:
  20. Jun 1, 2005 #19
    The past is more real than the present. For beings who observe anyway. Every observable moment you live, your every thought is always in the past. We can only exist in the present and predict the possibilities of the future. Time to me is rather a way we define one moment from another without knowing the exact order of every particle in the universe.
  21. Jun 1, 2005 #20


    User Avatar
    Gold Member

    You should read more. It's a lot more complex than you think.

    For example:
    1] "Particles moving around" has no intrinsic direction through time.
    2] Particles mazy decay, but they also fuse.
    Both of your examples are not dependent on a direction of time.

    In fact, it is precious hard (though not impossible) to find a good example of a behaviour that is dependent on a single direction of time.

    I highly recommend https://www.amazon.com/exec/obidos/...103-3891424-6089440?v=glance&s=books&n=507846.
    Last edited by a moderator: May 2, 2017
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook