# Time dilation

1. Apr 27, 2013

### lakshminarayan

what is the exact mechanism by which time dilates for a fast moving object.
Can the time dilation be explained by any other theory other than relativity.

2. Apr 27, 2013

### tiny-tim

welcome to pf!

hi lakshminarayan! welcome to pf!
there is no mechanism for time dilation

there's only the geometry, of space-time
Nope!

3. Apr 27, 2013

### phinds

It is an observational effect, not a local one. The moving object does not experience time dilation. Right now, as you are reading this, you are MASSIVELY time dilated from the frame of reference of a particle in the LHC because relative to it, you are traveling at very close to the speed of light.. Do you feel any different?

4. Apr 27, 2013

### lakshminarayan

How can there be geometry to space time, if space time is infinite?

5. Apr 27, 2013

### Staff: Mentor

Geometry is about the distances and directions between points. Whether the points are in an infinite space or not doesn't matter.

6. Apr 27, 2013

### lakshminarayan

But time dilation is a real phenomenon which has been tested. I might not experience time dilation, but I know time dilates for the moving object if I test it. How can it be relative when I know the result way before the relation is established between me and the moving object.

7. Apr 27, 2013

### HallsofIvy

You can't possibly know what time dilation is if you do not know how fast the object is moving relative to you.

8. Apr 27, 2013

### phinds

You misunderstand completely. Reread post #3

9. Apr 27, 2013

### Staff: Mentor

If some observer is moving relative to you, will be able to calculate that observer's clock dilation - his clock will run slow relative to your clock.

However, we could equally well say that the other observer is at rest and that you are moving relative to him - and then we will calculate that your clock is running slow relative to his clock.

Both calculations are equally correct. This is a real phenomenon that has been observed and tested. (And before you ask which clock is "really" the slow one, google for "relativity of simultaneity").

However, you'll notice that in both cases we are calculating the time dilation between a clock that is at rest relative to an observer and a clock that is moving relative to that observer. The entire calculation of time dilation depends on relative motion.

10. Apr 27, 2013

### ghwellsjr

The best way I know to understand Time Dilation is to look at the geometry of the spacetime diagrams for a couple of Inertial Reference Frames (IRFs) depicting the same situation and using the Lorentz Transformation process to get from one IRF to the other. The situation we will consider is a clock that is stationary in the first IRF. The spacetime diagram is simply a plot of the position (or distance from the spatial origin) of the clock along the horizontal axis versus time along the vertical axis. Here is the first diagram:

Pretty boring, isn't it? It shows that as time progresses from 0 seconds to 10 seconds, the clock stays at the spatial origin with the coordinate at 0. I also show each second of time as a blue dot.

Now we use the Lorentz Transformation to see how an IRF moving to the left at 60% of the speed of light would depict this same situation:

In this IRF, the clock is moving to the right at 0.6c. You can see that because at the Coordinate Time of 10 seconds, the blue line is at the Coordinate Distance of 6 light-seconds. You can also see that what took 10 seconds in the first IRF takes 12.5 seconds in this IRF.

Things take longer when they are moving in an IRF. And this is the simplest explanation of Time Dilation that I know of based on Special Relativity. Does it seem simple to you? If not, please let me know where you need some more explanation.

11. Apr 28, 2013

### Staff: Mentor

"relative" does not mean unknown or unpredictable.

12. Apr 29, 2013

### h_cat

Time dilation can be explained outside of the framework of relativity. There is even a mechanical explanation. If you assume that all matter is made of some form of electro-magnetic fields which can only propagate at c than you see that any circular process would come to a standstill if the corresponding system moves with c. Better said its clocks freeze.

ob_cat

13. Apr 29, 2013

### Mentz114

Matter is not 'made of some form of electro-magnetic fields', so that balloon won't fly.

14. Apr 29, 2013

### Forcer

Impulse is force by time. It's normal, if you give impulse to a particle also you give it time. Moreover, when a particle receives impulse, mass and time are increased in the same proportion.

15. Apr 29, 2013

### Forcer

No, but if it is possible to improve the understanding of relativity and what it describes.

16. Apr 29, 2013

### h_cat

There are theories which explain matter this way. And that was the questions right? Those who have brains to think for them self can look into them and take their conclusions. I know of course that the standard model doesn't explain the structure of matter that way. In fact it doesn't explain it at all. So any theory which does should be welcomed to enriched our understanding of our particles structure. That doesn't mean that they are complete or without contradictions. But they exist and that is a truthful answer to the posters question, right?

vb_cat

Last edited: Apr 29, 2013
17. Apr 29, 2013

### Mentz114

Where ? Can you give a reference ?

18. Apr 29, 2013

### krash661

interesting.

19. Apr 29, 2013

### h_cat

This is one of them, not very complete but interesting nevertheless. That said one has to look for themself there are a lot of weird theories out there some have a few good ideas. These are not my theories I only point out that there are theories which of course do not fit well into the standard model.
<<link deleted>> - the only one I can remember the link you need to google for more.

lc_cat

Last edited by a moderator: Apr 29, 2013
20. Apr 29, 2013

### phinds

La-la-land blogs do not count as valid references on this forum.

Last edited by a moderator: Apr 29, 2013
21. Apr 29, 2013

### h_cat

Somebody wanted some reference so that's the best I can do. But I got more and more the feeling I landed on the Spanish inquisition's forum. So I understand you right it is better to be quiet than two mention that there are theories out there which try two give answers.

ml_cat

22. Apr 29, 2013

### Staff: Mentor

To quote the mission statement on the main physics forum landing page (emphasis mine):

Our mission is to provide a place for people (whether students, professional scientists, or others interested in science) to learn and discuss science as it is currently generally understood and practiced by the professional scientific community.

23. Apr 29, 2013

### phinds

You agreed to the rules when you signed up and the rules include not posting unsupported speculation and not using unqualified references.

It is unfortunate that you feel that way, but this is a serious physics forum and if/when you make posts that do not follow the rules, you are likely to be called on it.

There ARE forums out there where you can post whatever you want, but this is not one of them because allowing that always ends up generating more heat than light.

24. Apr 29, 2013

### Mentz114

It's not unreasonable to ask for references. The one you gave is a collection of incorrect outdated theories or proto-theories. The last line of the article is

"The result is that all things in nature must experience a distortion of space and time that is relative to their absolute motion through space."
Absolute motion through space is a deprecated concept.

The correct answer regarding time dilation was given by Tiny-Tim in an early post.

25. Apr 29, 2013

oh my...