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Accelerating time

  1. Jul 24, 2006 #1
    Alright, so before I start off, I just want to say that I'm not very far into my physics career, but as I was reading on the forums here, I got to thinking about something...but, before I say my thoughts, I want to apologize if it's a stupid question. But here it goes:

    So, I was reading on the relativity forums today about how space and time are linked, which I think understand (or, understand as much as anyone can). I was wondering something; there is a force on something if it is accelerating (F=ma). Time is going forward at 1 sec/sec at a constant rate (far as I know?). If time were accelerating somehow...not exactly sure, but if it were, would that apply a force? I mean...if time had a constant positive acceleartion throughout the universe, would everything in the universe be pushed backwards in time (equal and opposite reaction, and all)? So I guess what I'm asking is can time be dealt with the same way as a spatial dimention?

    Sorry for maybe an odd question, but something that had been on my mind at work all day. Thank you!
  2. jcsd
  3. Jul 24, 2006 #2
    I too am not all that knowledgeable in physics (high school knowledge at best, plus a bit of thinking), but as far as i can tell:

    Time is just another dimension that can have various values. But since we are beings that base our existence on a certain continuity of time, it would be difficult to alter it (theory of relativity and all that).
    *stops to think further on the question at hand*
    Since i don't seem to be able to remember the exact theory on this, i'll have to goe with: any change in the value of time would only be recogniseable to us as a change in certain other aspects (probably the distortion in dimensions that were used to create the distortion in time).
    So yes, kinda. We just don't know how to manipulate it in a way that we can see yet. And i'm probably wrong on this as well.
  4. Jul 25, 2006 #3
    I think maybe I can simplify the picture a bit. Time never ever changes. And by that I mean specifically that your wristwatch never ever changes.

    Now, you may see other people's wristwatch slow down and even run backwards, but YOUR wristwatch will never change. Also you will never see anybody's wristwatch run faster than yours.
  5. Jul 25, 2006 #4
    Time dilation can be explained as the change in internal time of a stationary object (A) on a planet in relation to an object further out from the gravitational field (B) of the planet. In order to calculate the magnitude of change there must always be a reference point (A). If the magnitude of the dilation of time increases as the reference point grows further away (in a logarithmic progression, not a linear progression) then I would definitely have to agree with you and come to the conclusion that time is indeed a force. However, I believe this is more philosophy than physics because the mathematics to prove time dilation is not as influencing as actual experimentation. Theoretically, if we are to think of the progression of time as a force then we must think of the progression of space as a force as well.

    If we are to think of time and space as a force, then any fluctuation of time will influence a fluctuation of space. The fluctuation will occur simply for the two to remain at equilibrium. I do not agree with the concept that if time was a force then it would have the ability to push space backwards. The equal and opposite reaction of space would occur only to keep the relationship between time and space at physically viable.

    Not if you are to say that time is a force. If time was a force than the force of space would not be equal the force of time (if they were equal there would be no evidence of time dilation).
  6. Jul 25, 2006 #5


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    No, I think see what he's getting at. In the three spatial dimensions we can apply a force (any force) to push things around. If time is another dimension, is there possibly some sort of force that can push things around in the time dimension?
  7. Jul 25, 2006 #6
    Exactly what things would be pushed? The movement of matter is limited to the spacial dimensions. In this case, time can only be used to judge the progression of matter in space. The one known dimension of time follows separate rules than the three known dimensions of space. As I previously stated, if they obeyed the same rules then there would be no evidence of time dilation.
  8. Jul 25, 2006 #7
    A time dimension is not the same as spatial dimensions. Relativity states that it's wrong to consider it as completely separate and independent, but time is different than space.

    In regards to the wrist-watch remark, one will never see another persons watch moving backwards. Slower, or perhaps even stopped, but not backwards.

    One of the most important consequences of relativity is that time is relative. One can talk about the passage of time of an event as observed by people at different velocities; one cannot talk about any inherent "speed of time". Take your body for instance; what would accelerating through time mean? Would you age faster? Faster relative to what? The only (theoretical) way to observe anything relating to the "speed of time", be it speed, acceleration, or any other derivative or integral relation, is relative to a different body.

    In fact, this is what happens when a body is accelerated through space, or equivalently, under gravitational influnce. A stationary observer at infinity sees time slowing down for them.
  9. Jul 26, 2006 #8
    ok, but i don't see that so obvious. inside a train that is accelerating, you don't see the things in the same room going at different velocities than yours, but you can tell that you're accelerating by the inertia force. Is the original question something like this?
    actually, i can't imagine time accelerating, but if under some conditions, time was curved (stretched locally), yes, you should according to relativity experience some kind of " tidal force" reminding to inertia. Though i have difficulties imagining how it should feel :$
  10. Jul 26, 2006 #9
    Hi BoTemp,

    Thanks for reading my post - I was referring to antiparticles whose proper time does indeed move backward according to Feynman's theory of positrons, which I believe.
  11. Jul 26, 2006 #10
    Hi DaveC,

    Your post is interesting, but I am having difficulty with it. Spacetime consists of EVENTS. Spacetime is not a container in which objects "move".
  12. Jul 26, 2006 #11
    This thread needs to be in special relativity
  13. Jul 26, 2006 #12
    Hey everyone. Thanks for the posts, and maybe my question was a little too...out there for there to be a definate answer.

    I started thinking about this question when I was trying to understand time dilation. From what I understand, when an object is traveling at high speeds, it's length appears to be shortened (I think...right?) and it's time apparently slowed down. Since both is spatial and temporal dimensions were affected similarly by both being 'shortened' (I know, the time isn't really shorted, by slowed), I thought maybe there could be a force due to accelerating time the same as there would be a force due to something acclerating in the spatial dimensions.

    Again, sorry for the weird question, but I just like thinking about things like that. :)
  14. Jul 26, 2006 #13
    It is a good question. A lot of perplexity about relativity comes from people thinking about objects "moving" through time. Myself included.
  15. Jul 26, 2006 #14
    I think this a simple problem. Time is something relative to an observer: this observer defines what's a unit of time.

    Accelerated movement can be considered as the acceleration of time. Let's say we consider our time absolute. Let's then consider an area of the universe where relatively to our time, the time deccelerates. Now imagine an object moving at the speed 1 m/s. Say the object reaches the area in question. In one of our second it would travel 1 m. If "their" seconds in that interval has a value of 1/2 relatively to ours, they would have seen the object travel faster, at a speed of 2 m/s. The next second, "their" value of a second is 1/4 and thus the speed of the object increases to 4 m/s.

    As you can see, those "people" will see an acceleration of the object. When you talk about acceleration of time it has to be over another component. We could also consider "our own time" to accelerate relatively to an outside observer and realise how what he considers unaccelerated is accelerated to us.

    Same can be said about accelerated movements instead of linears ones. I just took that example to avoid going into calculus.
  16. Jul 26, 2006 #15
    You almost had me, but then I realized if time was REALLY slowing in the "room of decelerating time" then any object entering that room would slow down as well!
  17. Jul 26, 2006 #16
    I'm affraid I don't understand.. It all has to do with relative and absolute time. "Slowin down" wouldn't apply to an external observer. Time slowing down is just something that someone with an absolute time can define. Of course, the object itself would age less faster, but YOU will see it move at the same speed. The "area of slower time" is not relative to you anyway. It was just an example, instead of saying area you could just consider two persons, having different time flow.
    Last edited: Jul 26, 2006
  18. Jul 26, 2006 #17
    So let's say I'm sitting in my car, and I hit the gas, and start to accelerate in the X direction, with an accleration of Y m/s^2, there will be a force equal to mass*Y, and I will be pushed back into my seat with the same force (equal and opposite...I'm okay so far I hope. Been a while since school, haha).

    Now, let's say I'm sitting in my car, and I have a velocity of zero. And let's say, somehow, next to my blinker, is a knob that speeds and slows the passage of time within my car (and before I get yelled at, I know this can't work like that, but I'm pretending. And maybe it's too much to pretend and ask for a real answer). So I turn the knob, and my time begins to speed up, (second derivative of time with respect to...um....time....d^2t/dt^2...hehe...hm...maybe not). Anyways, would I experience any type of reactionary force? I'm trying to ask this question and have it not relate to relativity, because I'm thinking about a non-relativity situation. I think...

    I guess what I really want to know from my question is how much can we treat spatial dimensions and the time dimension the same? Can we look at it as just another spatial dimension, making four all together, along with X, Y, and Z, albeit a dimension that we (basically) only travely down one way at a (again, somewhat) constant velocity? Or do we have to distinguish that we have 3 spatial dimensions and 1 temporal dimension, because time is fundementally different from the others? Thanks again!
  19. Jul 26, 2006 #18
    Ok, I surely don't understand time dilation very well at all, but how can this statement be justified. In the twins paradox the twin that accelerates away from the other, then returns to find more time has passed for the twin that didn't travel. Surely at some point along the journey the travelling twin has to notice that the non-traveling twins wrist watch is moving faster than his own. Otherwise how do you account for the non-traveling twins watch showing more time passed?

    For this statement to be true, when the twins are reunited, they would have to show the exact same time passed on their watches.
  20. Jul 26, 2006 #19
    If what you mean is that someone outside the car will see a constant force and his time does not slow down, then as I was trying to explain, YOU will see it so that the force itself changes (meaning that the acceleration changes over time). You can't realise the slowing of your own time, because what is a second, is still a second for you. If what you mean is you see everything go slower, then the world's time and your brain's time are different. That is all.
  21. Jul 27, 2006 #20
    Maybe this makes sense and I am just too thick to understand. If Observer A (the one that leaves the earth and returns) shows 10 years passed. And observer b shows that 20 years have passed (and both observers can see each others watch the whole time). How is it that when they are reunited (and both watches show different times have passed) that observer A never noticed observer B's watch to run faster than his, even though observer B's watch shows 20 years have passed compared to A's 10 years.

    What it seems to me that you are saying (and I'm sure I'm wrong, but can't fathom why) is that the aging of each observer is independant of what their watch shows. But if both observers don't notice anything unusual in their aging compared to their own watch how can that be. I think it's agreed that when the two are reunited that one is physically older than the other, so if they both see each other the whole time, one sees the other aging faster. How else could there be a difference in their physical age if it wasn't so?
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