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LAN_403

Bored Chemist

Thu Jul 06 2006, 04:58PM

Registered Member #193 Joined: Fri Feb 17 2006, 07:04AM
Location: sheffield
Posts: 1022

With the same acceleration he would follow the same trajectory; acceleration is a vector quantity
The same magnitude of acceleration would be an interesting question and I guess that's what you mean.
It's an interesting question to which I don't know the answer but I guess that since the acceleration averages to zero (if he's accelerating South now then in half a revoultion's time he will be accelerating North) the time dilation will also average to zero.

Ben

Thu Jul 06 2006, 06:28PM

Vigilatny
Registered Member #17 Joined: Thu Feb 02 2006, 02:47PM
Location: NL
Posts: 158

Bored Chemist wrote ...

With the same acceleration he would follow the same trajectory; acceleration is a vector quantity
The same magnitude of acceleration would be an interesting question and I guess that's what you mean.
It's an interesting question to which I don't know the answer but I guess that since the acceleration averages to zero (if he's accelerating South now then in half a revoultion's time he will be accelerating North) the time dilation will also average to zero.

The time dilation does not depend on the direction, only the magnitude.

Bored Chemist

Thu Jul 06 2006, 08:06PM

Registered Member #193 Joined: Fri Feb 17 2006, 07:04AM
Location: sheffield
Posts: 1022

Interesting, does time slow down on a centrifuge?
Could this be a measurable effect for unstable particles decaying in a cyclotron?

Bjørn

Thu Jul 06 2006, 09:28PM

Registered Member #27 Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058

There is a clock postulate that says that the time is unaffected by acceleration and it is supported by particle experiments. That would mean that time is affected by the relative speed change that may be a result of acceleration(s) but not affected by acceleration itself.

As I understand it the clock postulate can't be proved or disproved by special or general relativity.

cbfull

Thu Jul 06 2006, 09:36PM

Registered Member #187 Joined: Thu Feb 16 2006, 02:54PM
Location: Central Ohio
Posts: 140

This is my personal opinion only, so please don't flame me.

I don't believe in the twin paradox. Something tells me that we are trying to interpret reality based on visual observation, which goes completely out the window when you start talking about travelling at the speed of light.

You cannot use visual observation to determine what is really happening. You must treat the matter as though you are blind, otherwise what is observed visually will drastically complicate and confuse the matter. Who cares what things look like at these speeds, what matters is what happens when your eyes are closed. If you want to discuss bizarre visual phenomena, then that is another matter altogether, and should be treated as a visual phenomenon ONLY.

Sorry, bit of a rant.

Chris Russell

Thu Jul 06 2006, 10:14PM

... not Russel!
Registered Member #1 Joined: Thu Jan 26 2006, 12:18AM
Location: Tempe, Arizona
Posts: 1052

So what you're really saying is that we can't use direct observation, or "too much mathematics" to understand the universe?

Carbon_Rod

Fri Jul 07 2006, 01:49AM

Registered Member #65 Joined: Thu Feb 09 2006, 06:43AM
Location:
Posts: 1155

Numerical abstraction aside, mixing Newton and Einstein is not a good idea. You may end up overcomplicating something simple or oversimplifying something complex.

If you were alluding to the popular theoretical loophole that allows time-travel buy using a black hole? Although mathematically plausible it has nothing to do with centrifuges and does not necessarily have to be related to Kerr hole like structures (science fiction fans always like this one.)

Not to mention this thread may disappear into a black hole even if the subject was tactfully approached.

""too much mathematics" to understand the universe?"

Bah ha ha ha lol -- Thatâ€™s the funniest thing I heard today... Descarte

cursed many generations with the notion that a few lines on a page can plot all vector spaces. He was wrong about many things, but made numerous contributions to mathematics.

"Just because you canâ€™t see it does not mean it isnâ€™t there."

Simon

Fri Jul 07 2006, 05:44AM

Registered Member #32 Joined: Sat Feb 04 2006, 08:58AM
Location: Australia
Posts: 549

Bored Chemist wrote ...

"Remember that velocity is relative and there is no absolute reference point in space. So how can you say that it is twin 1 who nears the speed of light and not twin 2?"
Because he is the one who gets pushed back in his seat by the rocket's acceleration. The 2 twins undergo different experiences and these different experiences have different outcomes. Where's the paradox?

BC, read my post more carefully and you'll see that that question was rhetorical and I gave it more or less the same answer as you did. I finished it off by saying that since acceleration is significant, special relativity isn't valid.

wrote ...

Given that all motion is relative you can't say which twin stayed still. from that point of view a skeptic might say "How come it's the correct twin that ages; you can't say which one moved?" With no acceleration that would be a true paradox. On the other hand only one of them actually gets in the rocket and gets accelerated- that's why his time "slows down" compared to the other.

As I said, it's an almost true answer, since it takes general relativity to see what happens to the twin who accelerates.

This is closely related to something that confused me before I studied relativity in physics. If motion is relative, how can you ever say whose time slows down in normal situations without acceleration?

Say I travel from near Earth to Jupiter at relativistic speed and Eve is watching me. We're both timing. Who measures the longer time? The key is to think about it in terms of time between events. The first event is being near Earth, the second is being at Jupiter. From my point of view, both happened at the same place (I'm still sitting in my spaceship). For Eve, one was near and one far. That's the difference.

What's the answer? Eve measures the longer time.

Bored Chemist

Fri Jul 07 2006, 05:56AM

Registered Member #193 Joined: Fri Feb 17 2006, 07:04AM
Location: sheffield
Posts: 1022

"I don't believe in the twin paradox. "
If you are prepared to think of 2 atomic clocks as twins then the"paradox" has been demonstrated.
One clock really does run slow.

WaveRider

Fri Jul 07 2006, 08:58AM

Registered Member #29 Joined: Fri Feb 03 2006, 09:00AM
Location: Hasselt, Belgium
Posts: 500

Clocks also run ever-so-slightly faster on the surface of the earth than in space. For example, GPS signals must take this into account, as well as the motion of its satellites, if errors are not to accumulate over time in the timing of its signals.

The resolution of the twin paradox lies indeed in who "feels" the acceleration (i.e. jumps from one inertial frame to another).. See the "adventure of Terence and Stella."

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