Speed of sight, not light

Originally posted by runetang
the matter which exploded outward during the Big Bang would've needed to travel *faster* than the speed of light for the first *7* seconds after the Big Bang occured, to be its present size.. the universe.

Actually I think the time scale may be infinitesimally smaller than that. Also, I believe the description of this event is about the universe itself, not just the matter in the universe, because nothing that we consider 'matter' had actually coalesced yet.

Ultimately, I think the 'out' in this explanation is that for this incomprehensibly brief time span....the universe, with its rules, laws, and physics, didn't actually exist. Conveniently violating Newtonian and Einsteinian physics.

Originally posted by Inannamute
To the poster asking how you figure out how far away a star is - much of it is done based on movement with regard to other stars or to the sun. - just as when you're traveling in a car, nearer objects seem to move fast while more distant ones move slower, the same is true for stars. If you can measure the position of a star in the sky at one equinox, and then at the other, you can use what you know about the earth's distance from itself at those points in the year, to figure out the size of the triangle those angles make.

Doppler shift also can be used to figure out things like binary star pairs, how they rotate, etc.

INANNAMUTE,
Thankyou for taking the time to explain this. Since we can't bounce a
radio wave or light beam off of a distant star to ascertain its distance, I
always wondered how the distance from earth was calculated. You have
taught me something new and I thank you for sharing your knowledge!
-C.W.M.