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Things close to the speed of light


This discussion originated in a statement by C.J. Cherryh herself

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>From: hposo@fltxa.helsinki.fi (Heikki Poso)
>Subject: Cherryhlist
>Date: Thu, 16 Sep 1993 22:28:22 +0300 (EET DST)
(...)
> Sublight, we all exist by Einstein's rules.... That's the law.   If we 
> stand imprudently EVA on the bow of a starship at .9999 cee and fire a 
> pistol, we notice a disturbing phenomenon:  the bullet will reach its 
> relatavistic limit instantly and hang there time-stopped just in front of 
> us, infinitely massive because of its velocity (as we are) and traveling 
> within our little packet of reality - because nothing in Einsteinian space 
> can exceed cee.  It and we go on together in the same moment.  Explosive 
> missiles or lasers fired just ahead of your bow will reach your target less 
> than .0001 split second before you do.  You might as well ram the opposing 
> ship as fire on their tail....
Whoops. This is simply not correct. Because the time the near-c ship perceives flows at slower rate, from their point of view the bullet behaves completely normally. For example, if you are moving at .9999c relative to another ship, for each second you perceive that ship perceives 100 seconds. (This supposes that you have done the accelerating. If it had been the other ship, it'd be slowed down.)

Another point - to reach infinite mass, you have to move exactly at c. This is impossible for all particles with mass, unless someone manages to disprove the General Theory of Relativity...

Thankfully these has never been of issue in Cherryh's books.

Disclaimer: it has been a couple of years when I last read a book about this. I can dig it up and even post some formulae, but I rather doubt there'd be much interest... :-)

(...)
Heikki
hposo@fltxa.helsinki.fi


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>From: David Zink <zink@panix.com>
>Subject: cherryhlist
>Date: Sat, 25 Sep 1993 04:29:57 -0400 (EDT)
(...)
> ibid, pp. 22-23.

> Sublight, we all exist by Einstein's rules....
> (...)
Could you get a date of publication on this? If this is the depth of her understanding of the phenomena, we may be wasting our time trying to figure out the physics behind her material...

The correct (Einsteinian, that is;) view is that standing EVA on the bow of your starship at .9999 cee, you will feel like you are standing still, watching the universe rush past you at .9999 cee. When you fire that pistol at the ship, also traveling at .9999 cee, hanging motionless in space ahead of you, the bullet will fly away in usual bullet fashion, and smack into the hull of the other ship, in usual bullet fashion, doing about as much damage to a meteor-safed hull as you would expect. The bullet will actually be travelling at .99990001 cee, but it won't make much difference to you.

In fact, anytime anyone starts to talk about the effects of traveling near the speed of light (you will notice that while I just did so, all I said was that there weren't any), you can assume that they are walking near the thin edge of inanity. .9999 cee must be specified in relationship to something. For instance, if you see a ship approaching you at .9999 cee, it will look brighter, most of the infrared radiation bouncing off of it will be reflected back to you as hard X-Rays, it will look shallower, if you naively attempt to calculate its mass starting from the trajectories of the dust and old shoes surrounding it, you will calculate a mass that is near infinite, and if you watch the giant clock displayed on the nose of the ship, you will notice that your own watch will show hours passing for every twitch of the giant clock's second hand.

At least that's the theory.
> Whoops. This is simply not correct. Because the time the near-c ship 
> perceives flows at slower rate, from their point of view the bullet 
> behaves completely normally. For example, if you are moving at .9999c
> relative to another ship, for each second you perceive that ship
> perceives 100 seconds. (This supposes that you have done
> the accelerating. If it had been the other ship, it'd be slowed down.)
The parenthetical is wrong: For every second of theirs *you* perceive the 100 seconds (of your own). For every second of *yours*, *they* perceive 100 seconds. All this follows from the basic tenet of relativity, which is that neither one of you will ever figure out who is standing still and who is moving...everything must be symmetrical.

CJ again:
> Whatever you've fired off insystem, incidentally, does not "fall" or go 
> away; it keeps traveling at the same speed.  Forever.  You might 
> conceivably run into your own fire; and certainly you can run into friendly 
> fire by accident, not to mention what the enemy lets off.  Space battle 
> will mean keeping track of every beam and projectile fired, no matter by 
> whom or how long ago, because if you meet it at a great speed (yours or 
> its) - just remember the way a .9 cee rock hits a planet.  Big crater.  No 
> ship.
This on the other hand is all accurate. With the caveat that without FTL, one needn't worry about running into one's own laser fire. (one's allies, however ...)

Actually I take it back--she's kind of ignoring the effect of gravity. Lot's of the stuff you fire will fall into the sun. You're falling too, however, so it will look like it is standing still.

(...)
	-- David
(...)


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>Date: Mon, 27 Sep 93 14:16:01 -0400
>From: "Nancy Silberstein" <silbersteinn@a1.mscf.upenn.edu>
>Subject: Cherryhlist/Everything but the Kitchen Zink
Wow! 26 September's List was full of great stuff for a non-techie. I am developing a morbid fascination with .9999 C (having already inquired of a technologically oriented friend (rna, Beth) what C was. I offered to quote him text as an aid in defining it but he very kindly explained that C was not a recondite designation. Such a nice man.)

(...)
njs  27-SEP-1993 09:31 


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>Date: Mon, 27 Sep 93 14:42:01 -0400
>From: "Nancy Silberstein" <silbersteinn@a1.mscf.upenn.edu>
>Subject: Cherryhlist/Publication Date
Dave, INSIDE OUTER SPACE was published in 1985 which probably means that C.J. wrote her submission early in 1985, at the latest.
njs  27-SEP-1993 09:43 


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>From: Jo Jaquinta <jaymin@maths.tcd.ie>
>Subject: Cherryhlist/99.9% of C
>Date: Fri, 1 Oct 93 8:51:45 BST
Didn't Suzanne Vega have a song about this. I think it went something like:

Ninety nine point nine percent of C
Mass increases towards infinity
It feels like normal but it isn't quite
Could make you afraid to take a space flight
You seem to me like a man on the verge of shrinking

Ninety nine point nine percent of C
Length decreases exponentially
Time dilates likewase as you converge on C
Two point nine eight by ten thousand KPS
Ninety nine point nine percent of C

...
:-)
 Jo Grant (...)

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