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What is the universe?
Posted: Mon Jul 18, 2005 5:22 am
by Frank
8) Does the term "Universe" include everything that exists regardless of whether man can photograph it or not?
Does the universe have a distinctive three-dimensional shape that can be visualized?
Are the most sophisticated telescopes in the world today limited to any particular distance?. Including radio and other specialized detectors?
Is the pinpoint of light we see as a star coming toward us in a straight line or is it a curved line?
Re: What is the universe?
Posted: Mon Jul 18, 2005 7:09 am
by makc
Frank wrote:
Are the most sophisticated telescopes in the world today limited to any particular distance?. Including radio and other specialized detectors?
We have discussed this one
here. Big guys said "
yes, telescopes are limited, because someone told us so, but we can't really reproduce the proof, so you're on your own here".
Posted: Tue Jul 19, 2005 10:15 am
by Kid
I don't think astronomers have any answers about that...
Posted: Wed Jul 20, 2005 3:57 pm
by Empeda
The distance we can see is limited because of the big bang:
According to current theory, up to 300,000 years after the big bang, the universe was opaque - that is, a photon of light could not travel very far without being scatter, so therefore the universe wasn't 'see-through'.
A process called recombination then occurred (which on a basic level involved the formation of atoms and molecules) which made the universe transparent, meaning that the average distance that a photon of light would travel before being scatterred was greater than the 'diameter' of the universe.
The consequence of this is if the universe is about 13 billion years old - we can only see a far back as 13billion-300,000 light years, and before that the universe was opaque. We do see the 'echo' of this early stage though in the form of the Comic Microwave Background.
I'll see if I can find a link to someone who can explain this 1000 times better than I can......
Posted: Thu Jul 21, 2005 7:25 am
by makc
Unlike that thread, "opaque" universe makes more sense to me. Looking forward for some links :p
Posted: Thu Jul 21, 2005 11:28 am
by Empeda
OKay - found some links on the Big Bang theory as a whole - this ones pretty good:
http://spiff.rit.edu/classes/phys240/le ... bb/bb.html
This one contains somes figures for those who like them:
http://cassfos02.ucsd.edu/public/tutorial/BB.html
Basically what I was trying to explain before was that we can only look back as far as to when the universe was opaque. This link might explain why a bit better!
Posted: Tue Jul 26, 2005 12:23 pm
by S. Bilderback
Here are some simplified answers to your questions, if you require greater detail just ask.
Q. Does the term "Universe" include everything that exists regardless of whether man can photograph it or not?
A. Yes, the universe is all energy, matter, and the spaces between
Q. Does the universe have a distinctive three-dimensional shape that can be visualized?
A. I will say no but that is based on opinion and not proof. The way in which gravity warps space/time may cause it to fold over on its self at the outer most reaches of the Big Bang. When ever values approach infinity, mathematical representations fail.
Q. Are the most sophisticated telescopes in the world today limited to any particular distance? Including radio and other specialized detectors?
A. Telescopes are limited to seeing back to about 100,000 years after the Big Bang prior to that the universe was completely opaque.
Q. Is the pinpoint of light we see as a star coming toward us in a straight line or is it a curved line?
A. Trick question. The photons of light travel in a straight line, it’s like tossing a ball from a merry-go-round, it travels in a straight line but does can look like it curves depending on the viewpoint. Gravity also can bend light a star on the other side of the universe may not be truly be in the position where it appears.