2006-08-15 11:50:08 · 18 answers · asked by Anonymous in Science & Mathematics ➔ Physics
28B LY's is only the part that is visible. According to GR, the universe can be arbitrarily large at any time. In an expanding universe, two points can have their separation distance increase at a rate greater than the speed of light c due to the expansion of space without violating relativity. Relativity implies only that light leaving one would never reach the other. They are refered to as "causally decoupled". It is *communication* that is limited to c. The common picture of the BB as a big explosion in space is entirely a misconception. The BB entails the expansion of unbounded space itself and requires a rudimentary understanding of noneuclidian geometry to comprehend.
2006-08-16 15:56:02 · answer #1 · answered by Dr. R 7 · 0⤊ 2⤋
(1) You assume that the Universe has a center. It does NOT.
(2) You assume that the expansion rate is at the speed of light. It is NOT.
The Universe has no center. Imagine that the Universe is the surface of a sphere (like a balloon). If we were to represent every galaxy as a dot on the surface, you can see that as the sphere expands, all the dots or galaxies moves away from each other, aka no center. Also, when you measure the size of the Universe, you would measure the circumference of the sphere (not the diameter). So if the Universe has been expanding at the speed of light from the Big Bang to until now, then the Universe is 14 billion light years across, not 28.
The expansion rate of the Universe has been measured, and it has been confirmed that the rate of expansion is accelerating. Also, understand that this rate is a function of the distance from our galaxy. So the further out we look, the faster the rate of expansion (you can check this yourself by looking at an expanding spherical ballon with dots placed on its surface equidistant to each other). So we know that there are places in the Universe that are expanding at speeds greater than the speed of light*. Hence, the Universe can not be just 14 billion light year across, but much bigger. How big? That I think is still being debated.
* - there is NO violation of Einstein's Special Relativity, because the expansion is due to space itself moving apart or growing, not due to anything actually moving.
2006-08-15 12:34:18 · answer #2 · answered by PhysicsDude 7 · 1⤊ 1⤋
Also the universe is not 28 billion lightyears in diameter, it is closer to 13.7 billion light years in diameter. And that is only the "known" universe, or what we can see right now.
Ok people, you guys are reading way too much into this. The universe has no center, and we do not know how big the actual universe is. However, the "known" universe's diameter is known, as that is how far we can see. Anything outside the known universe is spectulation and irrelavant, as we are uncapable of knowing at this time. The "known" universe is ~13.7 billion light years in diameter, using earth as the center.
2006-08-15 11:57:31 · answer #3 · answered by johngrobmyer 5 · 0⤊ 1⤋
14 Billion years old is not an assumtion. It isa proven fact. The universe is about 160 billion light years wide. Also proven by some calculation from measured data which scientist agree. For both being correct the universe must have formed at various points. Not at one point. or there is no limit of speed at which the object can travel. Only one could be right.
2006-08-15 12:23:13 · answer #4 · answered by Dr M 5 · 1⤊ 0⤋
I guess that I am the only one that knows this. (Laugh if you want...but this is the truth.) First of all, the figure of 13.7 Billion was the latest estimate, until the very recent data which now suggests it to be actually about 15 billion. This puts the diameter at 45 billion light years. (3X) The specific details are too complected to briefly discuss here but anyone who doubts me can research this and find out that it is true. I assume you already know this by the way you asked the question. If you are aware of this, make sure you pick me as the winner for being the FIRST one to answer correctly. Thank you.
2006-08-15 12:49:33 · answer #5 · answered by Smart Dude 6 · 0⤊ 2⤋
Nothing is wrong with that statement. If it's 14 billion light years old, it should definetaly be 28bill light years in diameter. After all, if light travels in one direction for 14bill years, and in the opposite for 14bill years, then the distance from point to point is 14+14 = 28bill. Just like diameter = 2R.
2006-08-15 12:17:37 · answer #6 · answered by Sara R 1 · 0⤊ 1⤋
It doesn't account for the inflaton that occurred a fraction of a second after the big bang... The universe expanded at speeds faster than light.
2006-08-15 12:30:59 · answer #7 · answered by hyperhealer3 4 · 1⤊ 0⤋
I would think that matter is not supposed to approach the speed of light without warping time. Even if it is 13 billion light years across, that implies a speed of near the speed of light for the outside galaxies (assuming some slow down in time). It is way beyond my comprehension though and I think it is also probably beyond modern physisists comprehension.
2006-08-15 12:05:07 · answer #8 · answered by JimZ 7 · 0⤊ 1⤋
What is wrong is that, like others have said, one you are assuming that the universe is a sphere, and second you are assuming that the universe expands at the speed of light which cannot be proved.
2006-08-15 12:25:30 · answer #9 · answered by dinizle26 2 · 0⤊ 1⤋
Well, first of all (maybe I am missing something here) but what does the age of the universe have to do with its diameter? How can you even assume a correlation between them.
2006-08-15 11:57:26 · answer #10 · answered by The Prince 6 · 0⤊ 1⤋