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?

"The cosmological principle is usually stated formally as 'Viewed on a sufficiently large scale, the properties of the universe are the same for all observers.' This amounts to the strongly philosophical statement that the part of the universe which we can see is a fair sample, and that the same physical laws apply throughout. In essence, this in a sense says that the universe is knowable and is playing fair with scientists." (wikipedia)

This is a belief rather than a fact. If what is observed is at variance with theory, then the theory is wrong.

Posted by broll on 2018-07-24 22:36:34