In article <E0xwmA9-0007nK-00@>, Nick Waterman <nick@> wrote:
Dalli L said:
I was just wondering, when they send the probe through the gate how do
they track it to "the other side of the universe"?. If the probe sent a
transmission through the gate itself surely it wouldn't give its
position? And unless they have instantaneous FTL communications, which
is unlikely, they wouldn't have recieved a radio message for billions of
years.
I'll admit that one worried me a bit too.
Right. It's science fiction, and therefore doesn't NEED to be
explained. I appreciate that, before I get flamed for it... But...
The only POSSIBLE explaination I could think of was that the probe
performed a quick survey of the sky and calculated it's position based
on a few "fixed" points like the center of the galaxy and a few other
reference points, and then having worked out it's position, it
transmitted this back through the gate.
And yes, I know it couldn't "see" the sky when it arrived inside a
pyramid, but there are other ways of surveying the sky than VISUAL
teloscopy, you know!
That's the only explaination that I'm happy about at the moment
anyway.
I believe (pending correction by our friendly neighbourhood astrophysicists)
that the correct method for identifying your position in the galaxy is by
a type of star known as a Cepheid Variable. These are stars which blink on
and off - slowly, over hours or days - and whose blinking rate is related to
their brightness. So if you can see one, and count how fast it blinks, you
can work out how far away it is. The positions of Cepheid Variables are
well known, as they are used as astrophysical surveying points, and a
reasonable sky survey could find them and guess position. The only problem
is that the survey would take a few days, not a few seconds. And I don't
know if Cepheid Variables are sensible as radio stars, so I suspect the
probe needs to see some sky.
But, as someone else said, that's not bad for Hollywood.
The plates on the Voyager probes gave position relative to known pulsars in
terms of number of wavelengths of hydrogen spectrum, if my memory serves me
right. Such an identification method could be done pretty quickly, but I
don't think we know many pulsars outside our local area. Certainly we don't
have all the pulsars in the Galaxy mapped. Pulsars do have the advantage
that they are radio stars, and that their rotation speed can be measured in
seconds, not hours. But then the Stargate system would need to be local to
us - still, stellar scales were always an SF minefield: even Babylon 5
suffers stellar scale problems.
Simon
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