According to general relativity, the faster an object moves, the slower time flows in relation to that object (time dilation).
This is because an object has a total velocity at any instant, and for all particles of matter this velocity is equal to the speed of light. This shows that as spatial velocity increases, temporal velocity will decrease to maintain the overall velocity.
So, when someone is sitting still, on a couch perhaps, and I get up and walk around (or get in my car and drive around) why is it that we both experience the same time flow? Because if I am moving at a faster velocity and my friend is sitting idle, shouldn't he have poofed into a future time in relation to me (even if this difference in time is incredibly small)?
Why doesn't my hand vanish into the future when I wave it and I remain standing still?
Because to feel the effects of time dilation you have to go very, very fast. Even going at a million miles an hour you wouldn't notice any difference in the time that passed for you and the tome that passed when you get home.
[quote="facool"]According to general relativity, the faster an object moves, the slower time flows in relation to that object (time dilation).
No...
Firstly it is Special Relativity that is concerned with time - General Relativity brings Gravity into it.
Secondly any object experiences time normally, regardless of speed. The difference is between objects travelling at different speeds - each will perceive time normally but there will be a difference. | Quote: |
| This is because an object has a total velocity at any instant, and for all particles of matter this velocity is equal to the speed of light. This shows that as spatial velocity increases, temporal velocity will decrease to maintain the overall velocity. |
This strikes me as gibberish....where did you get this from? If this is from a website we need to slap a health warning on it....
No particles of matter travel at the speed of light...nothing with mass can. Photons are essentially massless which is how they manage it...
| Quote: |
So, when someone is sitting still, on a couch perhaps, and I get up and walk around (or get in my car and drive around) why is it that we both experience the same time flow? Because if I am moving at a faster velocity and my friend is sitting idle, shouldn't he have poofed into a future time in relation to me (even if this difference in time is incredibly small)?
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No....I'm currently writing the second part of a three paper posting on Relativity which covers this in depth so if you can be patient for a few hours I'll try and post it up. In the meantime think along these lines :
you and your friend move at different speeds for a while. Relativity DOES say that your times will be different. Neither of you will notice anything since it is a 'relative' effect - your time will be different to his and his to yours but your time will be fine to you and his to him. There are numerous other problems - it only works when you are not accelerating/decellerating with respect to your friend or him to you...once you accelerate, decelerate or even turn a bend then you are in a different frame of reference completely and the effect is different.
Finally, as Conspirator points out, the effect is only noticable when the relative speeds are very high - a good proportion of the speed of light.
If you drive in a straight line away from your friend at (say) 100km/h for 1 hour then the effect will be that your time is 99.999999999999957% of his. Whilst this is calculable it is not measurable and your watch would certainly not show it.. | Quote: |
Why doesn't my hand vanish into the future when I wave it and I remain standing still? |
Why should it ? Just because local time passes at a different rate does not mean you will suddenly jump into the future. In the example above you would simply find that you were a tiny fraction of a second 'slow' compared to your friend | facool wrote: |
| Why doesn't my hand vanish into the future when I wave it and I remain standing still? |
Like Bikerman says, there's no reason to expect anything to "jump" into the future (or the past).
Special relativity simply says that from where you stand watching your hand as it waves, you will observe your hand as slower than you would if you were holding your hand still. That is, your watch would run slower, your fingernails would grow slower - everything would slow down. (Similarly, an observation device on your hand pointed back at you would observe you moving faster.)
How much slower will your hand move? Pretty much imperceptably. If you want to calculate it, here's the formula: t(hand) = t(head) * γ, where γ is:
When you actually go to crunch the numbers, i think you're going to find that γ is indistinguishable from 1 on pretty much any standard calculator. For example, estimate the speed of your hand waving to be 1 m/s, then v²/c² is ≅ 0.000000000000000011126500560536.... If you've got a calculator that can distinguish between √1 and √1.000000000000000011126500560536... (and then invert that), go for it.
There are approximations you can use, like this one: γ ≈ 1 + ½(v/c)². It should have only a tiny fraction of a percentage error at these speeds, and it gives γ ≈ 1.00000000000000000556325. Or in other words, time at your hand your hand slows down by a few attoseconds for each second, or about 1 second around every 5 ½ billion years. That's longer than the lifetime of the Earth so far.
It's always helpful to get a feel for the physics of things by doing calculations and then comparing the numbers to real things you can understand.Actually, you are all wrong. I tried this 'waving' experiment myself, only using a reverse method of waving secretly known to certain Tibetan tribes, and my hand actually went back in time, became the King of Austria and discovered the secrets of alchemy. When it returned back to me, however, it could not disclose the secret. It's only a hand.
Are you trying to disprove the theory of relativity? Well...nice try is all I will say.
| Indi wrote: |
| It's always helpful to get a feel for the physics of things by doing calculations and then comparing the numbers to real things you can understand. |
Nicely put!
