1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

What is time, and can it be changed?

  1. Oct 23, 2009 #1
    This question has surely been asked many times and it's not very scientific, well the level of the question asked is not scientific at all.

    Time is obviously directly related to movement, without any movement, there should be no time, but then again, everything seems to be moving on some level and i'm not sure if there can possibly be any absence of movement, however, if there was a space inside of which the 'construction' of every element was in a form that cannot change position relative to each other or any other space, would time exist?

    I was also wondering about time itself, does it exist as something more than just a measure of speed? Does it actually exist at all? Some like to call it the 4th dimension, even though the first three are related to space, and it seems to differ from them. The importance of this question is only when thinking about changing time and possible zones/universes/dimensions in which time does not apply at all or applies in a different way. Let's take a black hole for an example, most of actual information about it is still unknown, but it is possible that time has a different definition inside of it, if it is even in any way possible to find yourself, or well anything that is good enough to be used as a measure inside of it.

    So i assume that to globally change time flow is impossible, or not?

    However, as time is relative, changing time could have an infinite amount of meanings, for example, doing more things in a shorter amount of time would mean that for you, the time was faster than usual, but then again as you cannot go back in time and repeat the exactly same action twice, you have nothing to compare to but things that have happened under slightly different circumstances which is why you cannot say that the time went any faster or slower, just that it went different than it did another day, but that could be for many different reasons and not just your actions.

    The problem i see is that if time doesn't exist as a wave, or a particle, or anything that can be described as more of a measure, how could it possibly be changed? How could we possibly go to the future or the past, like for example people in the movies do.

    The question is basically about time, your time understanding, and the possibility of affecting time.
  2. jcsd
  3. Oct 23, 2009 #2


    Staff: Mentor

    Let me ask a related question back to you. If there were a space inside of which all lines were parallel would they be points instead of lines?
  4. Oct 23, 2009 #3
    Actualy you've asked a very deep and probing question and to properly answer it would take far more time and space to provide this detailed answer. :-) A short description is that mathematically it is a dimension similar to a spatial dimension from Einstein. However it is parameterized differently than a space dimension is ... by the speed of light (c) and the imaginary number (i).

    Probing your statement "Time is obviously directly related to movement, without any movement, there should be no time" slightly deeper, one could ask the following hypothetical question, if there was absolutely NO movement... everything was frozen would we still have 'time'. So here we can think of taking the entire universe down to absolute zero, and "stopping" all radiation (light, radio, etc.) waves as well. This introduces you to the thermodynamic properties of time...

    All fascinating subjects... one which we could debate for quite some... time. :-)
  5. Oct 23, 2009 #4
    Is there no length if there is no ruler there to measure it?
  6. Oct 24, 2009 #5
    They would be lines of the same or different length, however i'm not sure how it's related to movement, assuming that if they were parallel any movement they make would not be noticed by observing any of the lines individually, and if the lines are movement...once you stop them they should not be able to remain lines, but turn into points, actually i'm just not sure what you meant, most likely something different than this.

    I assume that this is a similar question, however, for example, if i was in a space where only one object existed(no other to compare it's length to, and being unable to compare it to the size of the space, somehow) and was able to see it, i wouldn't be able to say, "hey, this object is short" or "hey, this object is long" it wouldn't really have any essential meaning to me, and under these conditions the human kind would never name a measure length(even though it wouldn't be possible for people to exist if there were no other objects), does it exist? I really do not know, do things we will never be able to understand exist for us?
  7. Oct 24, 2009 #6


    Staff: Mentor

    Remember that you can plot the position of a particle as a function of time, this is called a worldline. A particle that is not accelerating has a straight worldline. Two particles that are not moving wrt each other have parallel worldlines. So, if it is possible to have a space that is filled with parallel lines then it is logically possible to have time without motion.
  8. Oct 24, 2009 #7
    If the laws of thermodynamics are correct and applies to all physics in this universe, you can't stop time and you can't go backwards in time. Absolutely Absolute zero has never been achieved, and heat doesn't go from cold to hot temperature.

    Of course, Einstein has proven that we are able to travel to the future, in relative terms. Yet these laws of physics may not apply at the quantum level.

    However, we can never be sure if something is possible or not.
    Last edited: Oct 25, 2009
  9. Oct 24, 2009 #8
    Reflecting on foundational logic and common sense I do agree with those who say you cannot bend time or space or mess with it in any way.

    Really we do exist in a time/space/event based reality that a 12 year old child can understand. Profound and complicated phenonema still has its foundation in an arbitrary simplicity. Some of the modern sciences and branches of maths/physics may well be proven to be based on imaginary and illusionary extrapolations.

    And just as in the magnitude dimension we have had to give acknowlegment to the infinity principle (using basic real mathmatics), so we have to admit to the existence of a superlative in the other dimensions. Time is eternal past and future. Space is never ending in all directions. Omniscience exists in the realm of understanding. Omnipotence exists in the realm of power.
  10. Oct 25, 2009 #9
    Why attach time solely to movement? My personal definition of time is that it is nothing more than a measurement of change. Now, I suppose someone will say there can be no change without movement, but when observing a leaf change from green to red to brown I don’t see movement, yet I can apply a measurement of time to the changing colors.

    For me it is simple. Time does not exist except as a measurement of change. No change….no time.

  11. Oct 25, 2009 #10
    Actually, you can only see color because light moves.
  12. Oct 25, 2009 #11
    I understand. However how would you be able to understand or measure time under such conditions? As existence is partially limited to our ability to understand, at least from our point of view.

    There are people that believe there was a beginning, which would make the past an expanding part of time, as we move from now to the future, which we constantly do. However what was before the beginning and if there was time or not would still be impossible to say, so what you have said is still correct in every way.

    Well there is also some micro based movement, if you take a look at the molecules of such a leaf in different times, you will see there has definitely been some movement.
  13. Oct 25, 2009 #12


    Staff: Mentor

    We (physical living beings, sentient observers) would not exist under conditions of no motion. You may not realize it, but you are asking a philosophical question, not a physical question. There is motion, so any question about what if there were no motion is non-physical.

    Logically and philosophically it is possible for there to be time without motion, physically there is motion.
  14. Oct 25, 2009 #13


    Staff: Mentor

    This post is non-scientific word salad.
  15. Oct 25, 2009 #14
    It's true, i do spend more time wondering what could be than what is, however, you never know when some great discovery might be made to break the boundaries making some things that currently seem impossible possible, and the whole thread is not only about motion stopping, but time changing(accelerating, decelerating, inverting, anything really), in any way possible, if there is any.
  16. Oct 25, 2009 #15
    Current knowledge of science doesn't deny the possibility of time travel, yet doesn't support it either. The most popular idea is by traveling through a wormhole, but without the discovery of an exotic matter such as antigravity, we would be crushed in the singularity.

    Yet the best evidence we have that time travel will not be possible is the non-existence of future tourists in our time. Of course they may deliberately blend in and we can ponder this question all day, which is thus more philosophical than scientific.

    Fundamentally we can already travel to the future by moving from one place to another.
  17. Oct 25, 2009 #16
    Just like temperature is what thermometer measures, time is what clocks measure.

    I try to keep things practical because if you start getting too abstract, you quickly end up with philosophical debates that miss the fact that truth in physics is ultimately settled by experiment and observations rather than through philosophical debate.

    The ultimate answer to a lot of "is X possible?" is "I dunno, can you think of an experiment that can be performed so that we can find out?" "Is time a wave?"

    The answer to this is "I don't know. Let's suppose time is a wave. What would be the consequence of that, and how can we get to an experiment that shows whether you can model time as a wave or not."

    Can we time back in time? "I don't know. I can say that we don't know of anyway of traveling back in time, and if we could it would cause major problems with our theories on how the world works."

    A lot of questions end up with the answers "I don't know, so how do we figure this out......"
  18. Oct 26, 2009 #17
  19. Oct 28, 2009 #18
    There are principalities and powers that could emulate this ( visitors from the past or future ) to deceive the masses. Example: In the occult world you can go to a seance (not recommended) and hold conversation with your past deceased friends or relatives. But are they really your late friends?? I say no. Many others would say no.
  20. Oct 28, 2009 #19


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    I would say it is the voice of the assistant of the charlatan, hidden in the closet, but that's just my opinion :tongue:

    Could we get back to a more "physical" discussion ? Or should we move this thread to the philosophy subforum ?
  21. Oct 28, 2009 #20
    I don't think we could return to the past, even in theory. By past mean historical events known to us. The best that you could do would be to enter a Past parallel to out Present but in a new dimension, possibly open up this new dimension, arriving at Event 0.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook