# Can somebody explain time dilation to me please?

Discussion in 'Physics & Math' started by maxjojo, Mar 13, 2017.

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1. ### originTrump is the best argument against a democracy.Valued Senior Member

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Newton assumed that time was absolute and he had no reason to believe it was not.
Around 1900 it was found that the speed of light in a vacuum was constant, independent of the motion of the observer or the source.
That led to relativity and the concept of time dilation.

In Newtons time the speed of light was not known, it was not even known if light traveled instantaneously from source to observer.

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5. ### maxjojoRegistered Member

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I am at loss to how you have answered my question or how the speed of light constant has anything to do with time passing by?

7. ### The GodValued Senior Member

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Back to Rpenner, but I think he has deplaned.

8. ### hansdaValued Senior Member

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My understanding is that:

Time Dilation is not slowing down of time but it is the slowing down of a clock. As the gravity becomes stronger, movement of clock becomes slower. Here time is as indicated by a clock.

So, as the clock slows down; we call it, time is slowing down.

9. ### maxjojoRegistered Member

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That sounds like a reasonable explanation, thank you.

10. ### The GodValued Senior Member

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So when the clocks slow down, what actually slows down? Try all the types of clocks please...like wrist watch, Casio digital, pendulam type, and of course atomic one.

11. ### gmilamValued Senior Member

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You do realize that speed has two components to it, right? Distance & time. (Miles per hour, feet per second, furlongs per fortnight, etc...) If everyone measures light at the same speed, independent of the motion of the observer or the source, then something funny must be going on with distance and/or time.

origin and exchemist like this.
12. ### exchemistValued Senior Member

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This is where I CAN comment.

The root of relativity is the observation that the measured speed of light does not depend on the motion of the emitting source relative to the detecting observer. This was totally counterintuitive and unlike any "normal" wave, which propagates at a fixed speed in a medium (e.g. water waves, sound waves), so that if the emitter or receiver moves in the medium the apparent speed of the waves, as seen from each viewpoint, alters. However, in fact, James Clerk Maxwell's mathematical description of light had already predicted that light waves did not need a medium. So physicists knew there was trouble brewing. The classic experiment was this one: https://en.wikipedia.org/wiki/Michelson–Morley_experiment

Various people, of whom Einstein was one, tried to work out how this could be and what the implications were. One of them was that, if light speed was measured the same by both emitter and receiver, irrespective of their motion, then length and time could not be fixed, since the only way to get speed (=distance/time) constant would be if both length and time themselves altered (yikes!), depending on the relative motion between the emitter and receiver.

All the rest then followed.

But, as I said before, if you are a normal person you will need to read about this several times, slowly and carefully, with a wet towel wrapped round your head, before you get it. It is very very counterintuitive indeed. But it seems to be true, since many, many observations have confirmed it.

Last edited: Mar 15, 2017
13. ### The GodValued Senior Member

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This is the greatest answer actually, this directly leads to length contraction and time dilation. Qualitatively constancy can be satisfied with length elongation and time contraction, but length cannot elongate.

14. ### maxjojoRegistered Member

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You could of just put d/t.

15. ### originTrump is the best argument against a democracy.Valued Senior Member

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Your understanding is wrong. Time dilation is about the rate of time changing not the slowing of a clock. You can disagree if you like, but you cannot change the definition of time dilation.

16. ### originTrump is the best argument against a democracy.Valued Senior Member

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Unfortunately it is an incorrect explanation.

17. ### maxjojoRegistered Member

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You are seemingly going off the topic of time and keep mentioning the speed of light , which is defined by d/t, time and distance being independent of a photon.

18. ### maxjojoRegistered Member

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What is the rate of time?

19. ### sweetpeaRegistered Senior Member

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Maxjojo. For clarification, is this the question or that of the opening post(OP) ?

20. ### originTrump is the best argument against a democracy.Valued Senior Member

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I don't feel like playing your silly game.

21. ### maxjojoRegistered Member

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The question was I could not understand time dilation or how time can slow down, the question above is just a question about what I assume Newton meant by absolute time.

22. ### maxjojoRegistered Member

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Asking the science community a question is a silly game?

23. ### originTrump is the best argument against a democracy.Valued Senior Member

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Trolling is a silly game.