In our current best model, the Universe is infinite and ever expanding. In this model, it is thought that every line of sight eventually ends at the photosphere (outermost visible layer) of a star. If so, it may be argued that the night sky should be brilliant - as bright as a typical star. The fact that the night is dark is known as Olbers' Paradox.
Here are some explanations:
1) Light dilutes in strength as distance^2.
2) The dust between the stars blocks the light.
3) The expanding Universe "reddens" the starlight to longer wavelengths, since space expands as the light waves pass through it.
Why are all of these wrong or incomplete? E.g., for number 3, why then is the night sky not brilliant at long wavelengths?
What is the most complete explanation, and what poet found the answer?
Each one of the 3 are technically correct but do not offer the complete picture so to speak. I believe two key points are missing.
4) The fact that there was an initial period where space was expanding at a rate faster than light, thus while the universe may be infinite, there is a point beyond which the light is not able to reach us, this is considered the observable universe. Within the observable universe there is a finite number of stars and thus not enough to fully brighten the night sky.
5) The atmosphere create a barrier which blocks out the light from the more distant stars (due to point 1 and/or 2). This can be illustrated by the pictures from space which show a significant increase in the number of visible stars.
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Posted by Daniel
on 2018-07-24 07:48:04 |
my attempt
