# Does time flow backwards of forwards?

1. May 8, 2012

### NWH

Does time flow backwards or forwards?

If we watch a ticking clock we would come to the conclusion that time flows forwards because we see time progressing one tick at a time. One, two, three, four, time must flow forward because things change and progress from one state to another. We know for us time only flows in one direction, it doesn't switch it up and change its mind, what is done is done and it's irreversable. However if time flowed backwards the same would be true, things would change and progress from one state to another, four, three, two, one.

Say for example, if we were standing in the street on a windy day we would find millions of particles of gas whooshing past. In relativistic terms both us and the gas are moving, in one frame of reference we are moving through the stationary gas, however in another frame of reference the moving gas is whooshing past our stationary bodies. Can we apply the same comparisons to the flow of time as we do the flow of the wind? On one hand we observe time to progress forwards, but we our selves don't move backwards in time, we move forwards in time, so if we were to examine time relative to our frame of reference, wouldn't we conclude that time actually flows backwards instead of forwards? We and time couldn't be moving in the same direction because then time would be standing still, everything would be at rest, but we know that isn't the case. We have to flow through time just as time has to flow passed us in order for the universe to exist, otherwise we'd never get from A to B.

Us >>>>> Time
Time <<<<< Us

Last edited: May 8, 2012
2. May 8, 2012

### PAllen

If you really want to ponder the 'nature of time' in an informed way, a really good place is the following essays by leading physicists espousing every point of view imaginable - but with real physical insight and mathematics as a foundation:

http://fqxi.org/community/essay/winners/2008.1

3. May 8, 2012

### NWH

We already know Relativity and Quantum Mechanics don't fit together, so surely a QM look at time is irrelevant here? Thanks for the link though, looks a good read!!!

4. May 8, 2012

### Staff: Mentor

Personally I just view time the same way I do distance. A measurement.

5. May 8, 2012

### NWH

But a measurement of distance has a direction in one of or all three dimensions of space, if you view them the same you must agree that a measurement of time has a direction also, surely not? The difference is we can move backwards and forwards across dimensions of space, we can not move backwards and forwards across the dimension of time.

6. May 8, 2012

### Staff: Mentor

Of course. But being simply a measurement, I don't see time as "flowing" or anything like that. At least not anymore than I see distance as flowing or whatever. FYI, we had a thread kind of like this one that was locked recently, so lets be careful on any speculation on what time "really" is or why we can or can't go backwards.

7. May 8, 2012

### NWH

Well, this thread is not to discuss about the nature of time, whether it exists or not, or whether we can go backwards or forwards, but whether time can be viewed in frames of reference like space can. We can say that one object is stationary in a system and that another object is in a state of motion, we can then use frames of reference to describe observations of events. Instead of using dimensions of space to describe an event, can we use dimensions of time to describe a moment? I hope you understand what I mean, I don't intend to turn this into a philisophical debate, I'm here solely to learn about Relativity, what it's able to describe and what its limits are, because I apply my own ideas to Relativity, I use it to think about thing you might not ordinarally think about, such as the direction of time. Whether those are scientifically backed I don't know, that's what I'm here to find out and I'm here to get people's opinions based on the facts that WE DO KNOW, not speculation.

Last edited: May 8, 2012
8. May 8, 2012

### Staff: Mentor

A proper description of anything REQUIRES both spatial and time coordinates. Relativity allows us to calculate how far we are traveling in both space and time. Traveling very fast causes us to travel through time at a reduced rate, hence our clocks run slower at high velocities. (That's the short version anyways) And by travel I mean the difference in position in each dimension after multiple measurements. Usually we reduce the spatial movement to a single axis, which is relatively easy, just make your direction of travel your one spatial dimension you are actually moving in. This lets us graph spacetime on a 2d graph.

9. May 8, 2012

### NWH

Thanks. Something I think about is this. If I was to stand absolutely perfectly still, even though I'm not moving across dimensions of space, I'm still moving across the dimension of time, correct? Can I say that I moved across the dimension of time in one direction from moment A to moment B? Is this sort of concept backed by Relativity? Is this a question one might ask?

10. May 8, 2012

### ghwellsjr

In Special Relativity, events already have a time dimension--and three space dimensions. If the time co-ordinate is constant for a set of events, then they define different places at the same time. If the three co-ordinates of space are constant for a set of events, then they define different moments in time at the same place. Your wish has already been granted.

11. May 8, 2012

### NWH

So does SR agree that time has one fixed direction that we must obey, despite the varying measurements of time we experience?

Can I use a dimension of space to describe the dimension of time to get new answers to questions?

12. May 9, 2012

### ghwellsjr

I suppose that since Einstein said time is what a clock measures and clocks run forward then SR agrees that time has one fixed direction. SR also affirms that time cannot stop which it would have to do before it could go backwards.
Yes, if you mean some graphical method but you would have to test those answers to see if they comport with reality. And I don't believe that those questions couldn't also be answered by other purely mathematical means.

13. May 9, 2012

### NWH

When I think of time I think of it like a river. I think of time as having a flow or a current to it which pushes against things that stand in its way.

So, if we were to imagine time as a spacial dimension, time would be a dimension in which I was in a constant state of motion, something that can speed up or slow down relative to other observers but something that can not stop. If we were to look at this from different frames of reference there are two observations we could make, A) I am in a state of motion or B) I am in a stationary state. Both answers are simultaneously correct, it just depends on whether we observe that I'm pushing against the river of time or that the river of time is pushing against me. Do you get what I'm saying?

Now, if SR says there is only one direction of time and that time can not stop, then can't we use this sort of thinking to determine the actual direction of travel relative to our passage through time?

I'm sorry if this goes beyond the realm of SR, but you never know with out asking questions! If you could approach this with an open mind and imagine it from my point of view that would be great!

14. May 9, 2012

### ghwellsjr

No one has any awareness that time is "flowing" any differently depending on their state of motion or acceleration or gravity or anything else. So I don't know why you would bother to make a statement regarding whether you are pushing against the river of time or the other way around. If anything, time just flows all the time identically for everyone. I don't think we need any additional conclusions from SR to affirm what we already knew about time, it just flows all the time identically for everyone.

15. May 9, 2012

### NWH

I thought it was light that was constant, not time. :/ We do have an awareness of time flowing differently because we can communicate with each other to confirm those differences.

16. May 9, 2012

### ghwellsjr

I was talking about your idea of pushing against time or time pushing against you. It never changes for you. Even when we communicate with each other and measure the other guy's clock and time as running slow, we don't perceive any difference in the "flow" of time for ourselves. It's only for the other guy. And he can't perceive any difference either, he's saying we are the ones that are affected.

Last edited: May 10, 2012
17. May 10, 2012

### NWH

Well I think all my questions have been answered, thanks! But before I finish I want to (and can) elaborate on this analogy of the flowing river of time to explain time dilation.

Imagine we have a flow of water down a stream that flows from north to south at a constant and uniform rate, and in that water we have two sticks with detectors on which tick a hand of a clock each time a particle of water brushes past the detector. Since both sticks are stationary an equal amount of water particles brush past the detectors and the hands of the clocks tick at the exact same rate. Now let's imagine one of the sticks starts to slowly move south in the direction of the current, suddenly the stick which is in motion is stimulated at a slightly slower rate than the other stick since the detector is moving in the same direction as the particles of water, suddenly the hand of the moving clock ticks slightly slower than that of the stationary clock, this is because the flow of water (time) interacts differently with the stick in motion than it does with the stick that is stationary.

To me time is like a river that flows and pushes against us, and how we move in that river changes our measurements and determines our passage through time.

18. May 10, 2012

### ghwellsjr

The problem with your analogy is that it would imply that time dilation is linear with the speed of the stick, correct? So if the stick were moving at 1% of the speed of the river, the time dilation would cause a clock to run at 99% of normal, correct? But the relationship of tick rate to the speed of light is not linear. For the same 1% of the speed of light, a clock will run at 99.995% of normal

19. May 10, 2012

### NWH

Indeed, although the faster we travel the greater the effects of time dilation right? If we could travel 100% the speed of light the ticking of the clocks would be 0%, that would be the equivalent of the stick breaking free and just floating on the surface of the water, because there would be no more resistance and time would cease to exist... I know this doesn't have much mathamatical value and I guess that expresses the limits of my capabilities, but it paints a nice picture. I can't help but view time in this way, I can accept the notion that time is just a measurement, but changes in measurements that are verified by experiments must be part of some strange quantum phenomenon and I look forward to the day we understand it better.

20. May 10, 2012

### yuiop

Why would it have to be a linear relationship? For example the force on a stationary object when air is flowing past it is proportional to the square of the wind speed.

21. May 10, 2012

### ghwellsjr

But since no massive object, including all clocks, can travel at the speed of light, there is no conclusion that you can say applies, such as the ticking of clocks would be 0%. It's not that time ceases to exist at lightspeed, rather you should think of time as being what a clock measures and since no clock can travel at the speed of light, there is no meaning to the concept of time at the speed of light. It would be like having an understanding of color being the wavelength of light and then asking what color is darkness. If someone said, well if darkness had a wavelength what would it be, you wouldn't try to answer the question, would you? Wouldn't you rather point out that the question doesn't mean anything? The concept doesn't apply. That's why I object to your statement, "If we could travel 100% the speed of light the ticking of the clocks would be 0%".

22. May 10, 2012

### ghwellsjr

Well, apparently NWH thinks it is something like a linear relationship because when you get "close" to the speed of light, it's just one more small step to reach it, instead of realizing that no matter how fast you are flowing in the river, the speed of light remains just as far away, it's just like you haven't changed at all from your starting point.

23. May 10, 2012

### NWH

Of course this is just an analogy to explain a concept, not an experiment devised to prove the existence of time as an actual force.

24. May 10, 2012

### ghwellsjr

In nature and in Special Relativity, time dilation is reciprocal between two observers. That is fundamentally important. How does your analogy explain that?

25. May 10, 2012

### Whovian

We've actually formulated a quite decent set of theories that puts Quantum Mechanics and Special Relativity together.