Rather than you staying young forever, from your perspective the places you left become older at remarkable apparent speed.
However from their perspective – which does you no good – you stayed young a remarkably long time.
Re a previous post asking for experimental evidence: For example muons, and other elementary particles, have a known half life of decay. But when accelerated close to the speed of light, from our perspective their rate of decay is slower by the amount predicted by the special theory of relativity. This applies not only to cyclotron and other accelerators, but also to natural muons from collisions of cosmic rays into our atmosphere.
[quote]Bill Roberts wrote:
I’d be interested in a further reply on that from someone well versed in general relativity, in the sense of being able to perform the necessary computations to actually solve for the given questions (not that I am implying that you may not be: I don’t know.)[/quote]
I did do general relativity and cosmology (particularly inflation theory and expansion), but if there are any physicists here they will no doubt provide more substantial answers than I can.
[quote]Bill Roberts wrote:
I don’t know for a fact but I had thought that the contraction was also of space, not merely the matter and radiation contained within it.[/quote]
You’re right actually, I worded that post poorly. What I should’ve said is something along the lines of “it’s the gravitational force collapsing everything back in.” What I was trying to say was that it wasn’t the universe shrinking that causes contraction.
Would you be able to oblige on the ending question from a previous post? It truly has me stumped:
[quote]To the perception (if it has perception) of matter moving outwards at exceedingly close to the speed of light, is it still moving “outwards” at the same speed, or does it perceive Hey dammit we’ve somehow gone into reverse?
My expectation is that the perception is that energy and momentum are conserved, and there is no loss of measurable velocity or change in direction.
If so then in what sense – to what observer – is the universe becoming smaller when it contracts? Assuming a universe that has a contracting phase.
Only to a transcendent observer? But we never allow those in physics. In the sense of physical constants? (postscript: but these are generally thought not to change in expansion)[/quote]
That was probably a stupid question. The answer could be as simple as in fact being slowed and then reversed in direction by gravity, similarly to how a projectile launched from Earth at less than escape velocity would slow and then reverse.
However in this case observations might perhaps be of ongoing forward motion due to matter further out contracting inwards even faster.
But I’d still appreciate your explanation, thanks.
[quote]stockzy wrote:
Rational Gaze wrote:
It works like this: one twin goes up in a rocket going at high-speed, and returns home. He will have aged less than the other twin who stayed on earth.
Special relativity basically says that a moving clock ticks more slowly than a clock at rest. But the reason for the twin paradox is hard to explain if you don’t have a background in physics.
This is really interesting stuff, and is still confusing me so i got this from
A point of clarification, don�¢??t be mistaken to think that if you traveled at the speed of light you would have stayed forever young.
In your reference system, the system that travels at the speed of light, you would grow old the same way as if you were at rest because your biological clock will pace the same. In that sense a photon is not comparable to a living creature. So what’s the story? Well in other reference systems that are much slower than yours, things will occur at much faster rate. So it’s better to think about it as if in slower systems times moves “faster”. It is only when you will stop or slow down to meet other people at other systems you will notice the RELATIVE time difference. This is why it is called the Theory of Relativity and the time difference (dilation) is noticeable only when you compare different reference systems. If Earth had moved at the speed of light, from our perspective in our reference system everything would stay the same.
So, even if you travel at the speed of light, you do grow old.
[/quote]
For all intents and purposes, we could be traveling at the speed of light or close to it right now. At least in reference to another system on the other side of the universe. So it’s not like we are aging slower or faster than that other system. Also, If I move away from a point of reference, Who is to say I’m not actually slowing down and that person of reference is remaining at the same speed? I mean if you look at the center of the universe as a direction and I take a spaceship and fly towards the center of the universe at the speed of light, Wouldn’t I really just be standing still and the person I left on earth would be still expanding away from me? So who is traveling and who does time dilation effect?
[quote]TomRocco wrote:
i dont know how complex the answer to this question is, but if it doesnt require much time to answer it i’d really appreciate it.
how would you prove that the moving clock slows time? How did scientists even come to that conclusion? we havent gotten to light speed yet (correct?)[/quote]
Not would. They did.(Read: Atom clocks, two planes) No one ever said you would need to travel near the speed of light.
Time dilation happens at every posible velocity, of course the magnitude of the effect depends on the speed.