With all the light emanating from all the stars in the universe why is it dark on earth at night?

Answer 1

This is an old question; it's usually known as "Olber's Paradox." Follow the link for a complete explanation.

Answer 2

If the universe is finite, as claimed by BigBangers, no explanation is needed, but I believe the universe is infinite.

If you assume Hubble’s “constant” is constant (just to simplify the problem), you can easily calculate a distance at which objects are moving away from us at the speed of light; I think that is similar to how BigBangers get the number 13.7 billion light years. The closer you get to that distance, the greater the red shift and the less energy is contained in the light (in the observer’s frame). At even greater distances, objects recede faster than light. So even if the universe is infinite, only a finite portion of it can ever be seen. (Note: Faster than light velocities do not violate relativity. The 4D space-time of general relativity covertly redefines velocity. The instant the pilot puts the pedal to the metal, the destination may become light years closer than it was the instant before, but the velocity of the destination remains zero. This permits a space ship to reach its destination in less time than it takes for light to get there—without ever moving faster than light. In a 3D version of general relativity, c is the speed limit for two objects passing one another, but there is no speed limit for distant galaxies ahead or behind an accelerating observer.)

Perhaps another clue to keeping the universe cool may be found in the conversion of dark energy to new space. The expansion of space is an infinite heat sink.

Furthermore, Stephen Hawking’s insane ramblings not withstanding, we have no way of knowing what the universe was like 13.7 billion years ago. Shouldn’t we understand gravity before extrapolating Newton’s equations that far into the past? Maybe there were no light sources then in existence whose light could now be reaching us from such a distance.

Answer 3

A. The atmosphere blocks out a lot of it.
B. The stars are too far away to shine like the sun does.

The farther away the star is, and the smaller it is, the dimmer its light appears to us.

Answer 4

intensity of light decreases by the square of the distance from the souce of light. the stars you see, that is true stars and not planets reflecting our sun's light are far more distant that our own sun. were we to be the same distance from each of the stars you see as we are from the sun, then earth would not experience night.

Answer 5

It's the number of photons landing on the Earth's surface - at night, the photon density is much reduced.

Answer 6

"Dark matter" absorbs the light.