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

B Why do we assume the existence of time (flow)?

  1. Feb 19, 2017 #1
    As I understand it, there is no solid definition of time other than the entropy is an arrow of time flow. I believe that physics equation would work regardless of the direction of time flow. What would be the implications if we assume that past, present, and future events are part of the existing universe (i.e., stop thinking of time as something that is flowing from past to present to future)? Thank you for your responses.
  2. jcsd
  3. Feb 19, 2017 #2
    That time has a direction is a fact, it can't really be disputed, no matter how we think about it.
    People will always be born young, grow up, and eventually die.
    Thinking about it differently won't change that.
  4. Feb 19, 2017 #3


    User Avatar
    Staff Emeritus
    Science Advisor

    Time is already incorporated into General Relativity as part of spacetime, of which all events and objects are already present. That we consider time to "flow" from past to future is a requirement to make theory and observation match. Shattered vases don't reassemble themselves, despite the individual equations not caring a wit about whether we have a +t or a -t.

    As rootone said, changing the way we think about time isn't going to change our observations that time does indeed appear to flow from past to future. Any hypothetical gains we would get from modifying our thinking are exactly that. Hypothetical. (Does it make it ironic that we can't know what would happen because it's in the future??)

    Anyways, since threads on time usually attract personal opinions and speculation, and because you're asking about something which is inherently unanswerable, I'm going to lock this thread.

    Thread locked.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook