[The last renewal of this page: April 18, 1999]

Please do not say "What a silly question!". Please think it again. Let us suppose that the space is the infinite, and perspectively, it's filled with stars uniformly. I draw your attention to two rules important.

1.The brightness of the light is in inverse proportion to the second power of the distance. (As the distance get twice, the brightness of the light get decreased to 1/4.)

2.The visible range is is directly proportional to the second power of the distance. (As the distance get twice, the visible range get four times.)

These two rules mean that however the distance is far away from the earth, as many times of stars as the ratio of the decrease in the bright- ness are visible, and thus, as long as the space is the infinite and it's filled with stars uniformly perspectively, the sky should be completely occupied with numbers of stars like in mosaic, and a whole sky should be shining in white. How is it? Isn't that interesting?

This is so-called "Paradox of Alverse", and is a question asked by german atronomer Dr.Alverse(1758-1840), and he couldn't give it an answer before he passed away.

This paradox is resolved about 100 years later, by the big discovery made by astronomer Dr.Hubble in 1929. Hubble discovered that "The space is expanding, getting separated each other, and as the distance get more, greater in speed, and finaly, it reaches to the light speed."

There is no way to see the light which is emitted from the object leaving from us at light speed. It is absolutely the same as that you never get downstairs even if you try to descend down at the same speed on the escalator to go upsatirs. Infinite numbers of stars in the sapce are leaving from the earth, getting more speed as it gets far, and finally, the speed reaches to the light speed, resulting the energy of the light to be zero. Before the rule, "The brightness of the light is in inverse proportion to the second power of the distance" works, the energy of the light itself toward the earthe has been weakened, as it gets far.
Why it's dark at night? That's because the space is expanding!


How large is it the Space?

Actually, it is unknown. However, I dear say it's 15 billion light years. (Please refer to the "A Structure and a scale of the space") The reason why is that it's been 15 billion light years since the space was born, and the farest object that we can see is at that distance. (The light emitted 15 billion light years ago is now visible.)

There is one problem here. That is the fact that the space is expanding as I described above. As it gets far, it gains more speed, and finally it reaches to the light speed, and then it is impossile to reach to the earth forever. This means that even if a star exists at 15 billion light years, it is possible to be unvisible, and further more, even if a star exist at 50 billion light years, it would be impossible to see it forever.


Why there is a star without twinkling in the night sky?

Generally, stars(fixed star) twinkle however bright they are, however, the planets normally don't twinkle. The bright Venus at evening sky, a red Mars, a yellow Jupiter, and the Saturn stay in the night sky without twinkling, and it's easy to tell the difference from many fixed stars.

Twikling stars(fixed stars) do not actually twinkle themselves varying the strength of the light. The stars being observed from the Space Shuttle do not twinkle. When the light from the fixed stars pass through the atmosphere of the earth, due to the turbulance or stream of the air, (sintilation)light gets refracted and twinkled.

A planet looks just a dot just the same as a fixed star with the naked eyes, however, with a simple telescope, the planet has a shape of a circle obviously, not a dot, while a fixed star stays in a dot however high the magnifying power is, and never be in a circle shape. (They are so far! Even the nearest fixed star, Alpha-Kentauri is located at 4.3 light years away.) Light getting into the atmosphere as a dot like fixed stars is able to be affected by the movement of the air and twinkles, but the light getting into the atmosphere as a bundle of the light like the planets is not affected, and does not twinkle like fixed star.



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