Suppose it was immediately after the Big Bang and the Universe was the size of, lets say, a football field. Would it take the same amount of time for a light beam to travel from one side to the other as it would now, with the Universe at it's current size? Basically, would it take hundreds of billions of years for a light beam to cross 100 yards in a football field sized Universe?
2007-02-27 04:18:40 · 4 answers · asked by Cpt_Zero 2 in Science & Mathematics ➔ Astronomy & Space
The speed of light in a vacuum is a constant. It has never, will never, and cannot change.
That being said, in the early universe (t<300,000 years), then it might have taken light longer to go the same distance, because it wasn't in a vacuum - the light had to move past, through, or around the huge field of debris that was the early universe.
My guess is (though I don't know and I'm too lazy to look it up) that the early universe was pretty bright, but that light from one side wasn't making it to the other because it couldn't penetrate the clouds of dust, gas, and free atoms that made up the early Universe at the time. Most light came from sources pretty close to the observer, by virtue of heat energy.
2007-02-27 04:24:04 · answer #1 · answered by Brian L 7 · 0⤊ 0⤋
First the speed of light never changes. It is always the same. For your question of taking as much time to cross the universe now as it would have back then you have to first stop and think the size of the distance you are crossing. We know that light travels as 186,000 miles a second. Lets say the we are going to put your question to the test. If we had a distance of 186,000 miles it would take light 1 second to cross this distance. If we were crossing a distance of 372,000 miles then it would take light 2 seconds to reach each end. It would take light more time now to travel the universe because there is more space to cross.
2007-02-27 13:17:57 · answer #2 · answered by Lighting Bolt 7 2 · 0⤊ 0⤋
Some people here claim that the speed of light cannot ever change. I agree in principle, but not in the same context as stated here. The speed of light is considered to be constant in space-time. There is no incontrovertible evidence that it must be constant in space, as claimed by others here. I consider that this is pre-relativity thinking, which ignores the concept of space-time. The speed of light through space may well change over time.
That being said, it seems to me to be most reasonable to consider that as the size of the universe increases, the time taken by light to traverse the breadth of the universe must increase as well.
2007-02-27 13:51:26 · answer #3 · answered by Fred 7 · 0⤊ 0⤋
That is a possibility that has been (and still is being) considered. Unfortunately nobody has been able to come up with any experiment or measurement to prove or disprove it.
2007-02-27 12:26:57 · answer #4 · answered by campbelp2002 7 · 0⤊ 0⤋