Why is the universe black? 20

The universe is average on a large scale, which can be understood as having stars ** in any straight line from the earth (seen as a point), so it is too narrow to say that stars are too small

In fact, because stars (almost the only luminous matter in the universe) are generally far away from Earth, light energy is dissipated during propagation. What's more, there are still a large number of interstellar materials in the vast desert space: all kinds of gases, dust, etc., so most of the light of the stars is blocked by them, and the human eye can see very little light.

The universe is not infinite.

15 billion light years.

This is an Olbers paradox.

Because there is no light in the universe.

You should know about the Hubble telescope, of course, it's almost out of work.

The Hubble telescope can see farther than any other telescope, observing galaxies 12 billion light-years away. This not only expands the space, but also the time. Because it took 12 billion years for the light of these galaxies to reach us, it allows us to understand what it was like when the universe was first born.

With the violent flash, the huge pressure caused the gas to condense, and then the first stars were formed, and 1 billion years later, it was the peak of star birth, and since then, the speed of star production has gradually weakened. Astronomers have already guessed that there are not only stars in the universe, but also 90%-99% of dark matter, which are stars that are close to death, black holes, asteroids, interstellar gases and large amounts of cosmic dust, which are hidden in the distant deep space.

It is because there is a large amount of dark matter in the universe that the universe appears black.

Why is it black without light?

The distorted space of the universe blocks out the light.

Sometimes the stars we see are hundreds of thousands of years or hundreds of millions of years ago, and optically speaking, people see objects by the reflection of light (the answers of the two upstairs are OK).

Because the eyes respond to the brain when we don't receive light, it's black as we call it, and the universe is too big for too little light to reach our little eyes.

Because the universe is mostly vacuum, the light from the stars is not reflected and thus cannot enter the human eye, so the universe we see is black!!

The universe is not actually dark, but there is so little light that can reach the human eye that we can't feel it.

Your question is similar to the "Olbers paradox", but there are no infinite stars.

Just search for the "Olbers paradox". The big ** theory may explain this phenomenon.

Because the age of the universe is finite, light has not yet had time to travel to every corner of the universe.

Look closely: The universe is black mainly because it is a space without light. Although there are many objects such as stars, planets, nebulae, and galaxies in the universe, the light they emit does not have enough energy to penetrate the entire universe, so only a small amount of light reaches our eyes or telescopes.

In addition, the expansion of the universe has also led to a redshift of light, which makes the light emitted by objects far away from us become more reddish, and even turn into microwave radiation, which further reduces the visibility of the cosmic mountain elder repentance. So, although there are many objects in the universe, they don't emit enough light in the entire universe to make the universe appear bright, so that we see a black space.

Because the universe is a very vast and vast world, when people stand on a planet and look at the universe, it will appear black.

This is because not every galaxy in the universe has a glowing planet, so the universe looks black.

Mainly because there are not so many luminous bodies in the universe, so there is no light, and it looks black.