Re: The concept of time contractrion in special relativity
From: Androcles (androc1es_at_nospamblueyonder.co.uk)
Date: 06/12/04
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Date: Sat, 12 Jun 2004 00:21:08 GMT
"sal" <believer@nospam.org> wrote in message
news:59822191fef340f54f5d16cd28094e49@news.teranews.com...
| On Fri, 11 Jun 2004 10:45:18 +0000, Androcles wrote:
|
| >
| > "sal" <believer@nospam.org> wrote in message
| > news:7cc8b97534d5a72f3fddf1e6a51bd375@news.teranews.com...
| > | On Thu, 10 Jun 2004 23:52:19 +0000, Androcles wrote:
| > |
| > |
| > | > "Paul B. Andersen" <paul.b.andersen@hia.no> wrote in message
| > | > news:ca9ggu$rqb$1@dolly.uninett.no...
| > | > |
| > | > | "Androcles" <androc1es@nospamblueyonder.co.uk> skrev i melding
| > | > news:P5xxc.1752$rY2.15869039@news-text.cableinet.net...
| > | >
| > | [ snip random quantity of summer-rerun text ]
| > | > |
| > | > | Androcles wrote:
| > | > | | The Androclean transform is called wrong by Paul's assertion,
but
| > | > | | it isn't wrong at all. It is every bit as valid mathematically
as
| > | > | | Einstein's. Paul cannot prove it wrong at all. Paul cannot be
| > bothered
| > | > to do
| > | > | | the math, Paul guesses, Paul has been proven wrong. Paul isn't a
| > | > | | mathematician, or even a good student that does his own
homework.
| > | > Instead,
| > | > | | he simply insists he is right, and wears a blinker over one eye,
| > only
| > | > seeing
| > | > | | to the right and never to the left. Paul hasn't lost his mind,
he
| > | > | | cannot lose what he never had to begin with.
| > | > |
| > | > | I can but bow my head in humble admiration of the mathemagician
| > | > | Androcles.
| > | > |
| > | > | > I think it has something to do with the faster you go, the later
| > | > | > you
| > | > arrive.
| > | > |
| > | > | Quite.
| > | > | Time runs backwards
| > | > |
http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/AreYouSure.html
| > | > | and contracts
| > | > |
http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/Contract.html
| > | > |
| > | > | Paul
| > | > Does time run backwards, nTaul?
| > |
| > | Yes, of course it runs backwards. Everybody knows that. Simple,
| > | elementary result, they should mention it in freshman physics classes
| > | but for some reason they don't. I guess it's like time contraction,
| > | huh?
| > |
| > | Anyway, here's the ad you surely expected:
| > |
| > | http://physicsinsights.org/revolving_astronaut.html
| > |
| > | Of course it's one of those disappointing "you can't really see it"
| > | effects, but it's still kind of cool, IMHO.
| >
| > sal: Imagine a spaceship in orbit around a distant planet. Imagine that
| > the Earth lies in the plane of the orbit.
| >
| > At one point in the orbit, the ship will be traveling directly toward
the
| > Earth. At that moment, in the momentarily comoving reference frame of
the
| > ship, the Earth lies far ahead of the ship. Since the ship is moving
| > toward Earth, that means that time on the Earth must appear far ahead of
| > "local" time on the planet below.
| >
| > Androcles: Why?
|
| The L-word, of course: The Lorentz transform. tau(Earth) =
| gamma*(t(Earth) - x(Earth)*v), and x is several lightyears, so the x*v
| term is really large, and Earth time is offset by a large amount from time
| on the nearby planet. It appears in the future. (Unless I got the sign
| wrong, in which case it appears to be in the past, but I didn't in this
| case. Here's a little mnemonic: The moving observer moves toward _future_
| times in the stationary frame. So, when the ship is moving toward the
| Earth, Earth-time appears to be pushed forward. In fact that's another
| way to look at time dilation, but then we're in danger of getting back
| on-topic so I'd better drop that line of reasoning...)
:-)
| > If the captain has his feet up watching England play
| > soccer in Portugal he might notice some dopplershift,
|
| Oh, but here you're just talking about what the Captain actually _sees_.
| This is reality here you're discussing, not the MCRF view. And in this
| case SR predicts exactly what you would expect it to predict, which is
| what you're describing.
|
| It must predict this, of course. Proof: If it didn't predict that things
| would look pretty much like they obviously do look, then it would
| have been rejected years ago, and it wasn't. QED.
Huh? You mean France won?
Impossible!
English fans have been granted Portuguese permission to smoke dope to keep
them calm!
|
| > the players may
| > appear to be running too fast and the commentary a little high pitched,
| > but at the velocity you are talking about I'm sure his receiver will
still
| > remain in synch and he'll enjoy the game. If not, he can always watch a
| > taped cooking show instead. Or maybe snooker.
|
| I've read that snooker is really boring to watch, because the pockets are
| really small and the tables are really huge, and so none of the fancy
| moves pool players in America use are practical.
You have see a 147 score, live, man!
So everything's just
| straight shots, which isn't very visually interesting. Is that really
| true?
Good grief! Placement of the cue ball is EVERYTHING!
Have you no soul?
|
| > I still think it will some
| > years late, though, if he's more that few light years distant.
| >
| > Sal: Looking at the Lorentz transform, if ship's time is zero,
| >
| > Androcles: Why would ship time be zero?
|
| Because zero's easier to compute with. There's a lot of multiplication
| involved in computing the transforms, and if we set the time to zero, then
| half of it is almost guaranteed to be error-free (almost nobody ever makes
| a mistake multiplying by zero).
You mean ksi * sqrt(1-v^2/c^2) - x' = 0?
I like e^(i*pi) + 1 = 0, myself.
Wow! How about that?
e^(i*pi) + 1 = ksi * sqrt(1-v^2/c^2)
|
|
| > Jeez, if he kept on setting his
| > clock back to zero, he's bound to miss the game. Probably he'd sleep
right
| > through it. I will, too, I expect.
|
| Yeah, well, snooker's like that, as I said.
|
| Or did you mean the soccer game?
Good grief (again).
The England - France game in Portugal hasn't already happened yet, unless
you are orbitting Alpha Centauri! Who won? I want to place bet.
|
|
| > sal: and velocity is positive, then Earth's velocity relative to the
| > spaceship is negative, and current time on Earth will be given by
| > v*gamma*distance. Again, the clocks on Earth seem to the astronauts to
be
| > set far in the future.
| >
| >
| > | By the way, why do you call Paul "nTaul", anyway? Is it supposed to
be
| > | derogatory?
| > Oh, that's an easy one. nTaul thinks the period of an orbit, which the
| > rest of the astronomy world calls "P", is nT, n an integer. This is
| > because T is an interval of time called a "period". He manages to derive
| > dtau/dt = 0 < 1 from it. No, it isn't derogatory, it is polite. I'm
using
| > his term. Although nTaul has a Ph.D. in Confusion, calling him "Doctor"
| > seems a little too formal.
| > From 20 Jan 2004:
| >> Logic isn't your strong side, eh?
| >>
| >> Consider the following mathematical contra example: dtau/dt = 1 -
| >> cos(2*pi*t/T), where T is the period that make you fart so: dtau/dt =
| >> 0 < 1 when t = nT, n integer.
| >
| > See how time stops once per orbit ?
|
| Yes, of course ... or rather, no, not at all:
|
| It stops twice per orbit.
Ahh...yep, I have to confess I had missed that.
|
| But you can't tell if time stops for you, of course, because you can only
| experience things while it's moving.
|
| This is one of the reasons it's silly to argue about whether the rate at
| which time passes is "constant" -- I mean, really, constant relative to
| _what_?
|
|
| > The reference to flatulence comes
| > from ...
|
| Yes, yes, I was actually around during at least one of those episodes...
|
| Personally I find beans do it to me worse than the newsgroup, but then,
| we're vegans here, so we eat a lot of the things.
|
| --
| To email me directly, take out nospam and put back physicsinsights.
Wasn't Spock a vegan?
I thought Vulca was part of the summer triangle...
Androcles.
- Next message: John Schoenfeld: "Re: Schoenfeld-Einstein Relativistic Force"
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- In reply to: sal: "Re: The concept of time contractrion in special relativity"
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