[ previous ]
[ next ]
Why night is dark? 3

I'm sorry to have kept you waiting. Now let me work out an answer to the question 'why night is dark?'

When I presented a question [why night is dark?' I gave you notice that an answer was judged 'to be 'correct' based on the knowledge or theories of 'astronomy' and 'cosmology' at the time of the opening of the 20th century when the question was firstly presented or at the time of the early 20th century when the answer was recognized to be 'tentatively correct', hence nobody knows whether this 'correct answer' would correct for ever. Such situation is something like a 'circadian rhythm of living beings/ which natural science has had from its birth, it may be 'fate' or a 'chronic disease' OR 'freshness' or 'wonder'.

However, the 'answer' has been accepted as a persuasive 'synopsis' by 'astronomy' or 'cosmology' in 2005, I dare say.


Repeating the question, it was that 'Provided that numerous stars equally exist in the cosmos, even though the sun exists near the earth, by collecting light of numerous stars, the total would be equal or brighter than light of one sun, hence the light when the sun hides itself behind the dark side of the earth, i.e. the 'nighttime', should be the same as that when the sun exists on the light side of the earth, i.e. the 'daytime', shouldn't it? Theoretically it should be so though, actually the 'nighttime' is dark and it only becomes faintly lighter by 'moonlight' or 'starlight'. Why is it so?'

The answer which was guaranteed as 'correct' by then most authorized scientists among numerous answers from around the world, thanks to the extraordinary prized money, was 'the cosmos has been expanding' that seemed too much simple, or contemptuous uninteresting one even the one we wanted to involuntarily throw a question back to somebody 'isn't that right?' Because everybody else expected a most unexpected answer. Of course it is difficult for us to quickly imagine 'the cosmos has been expanding', even after being lost in thought of it, that is an extraordinary idea, so dare say I.

Even though the belief, almost near the religion, that the cosmos has never been and will never be changed from the earliest times to the eternal future has occupied 99.9% of the human history, however not a few observatory findings which gave an impetus to asking 'By some chance the cosmos is expanding?' began coming out one after another in those days already. The 'red shift phenomenon' that clarifies why more distant stars go away from the earth more quickly is one of the typical samples, we can find the similar phenomenon in the change of a steam whistle from a distant train.

I think that the biggest key in this question is in this 'leap of idea' which connected the question 'the cosmos may be expanding' with the answer 'because the cosmos is expanding night is dark'.

Everybody thinks that if the cosmos is expanding what was the origin before expanding, reached the theory of the 'big bang' I described in the 'rise and fall of the cosmos', and further asked whether the cosmos will continue expanding or begin shrinking. Asking such a question leads to an interesting story of 'interstellar materials' or 'black matters', however I recommend you to read some appropriate guide books answering those questions.

Let's review the above story once more. I the cosmos is expanding, in particular more distant stars are going away from the earth more quickly, even though light of numerous stars is accumulated, brightness of light of the sun nearby the earth, i.e. the sun goes away from the earth most slowly, overwhelms the star light, doesn't it? That was an answer to the question 'Why night is dark?'

The attached photograph is the 'Hubble Telescope' named after Edwin Hubble, astronomer, who discovered the 'red shift' which is said to be evidence of the expansion of the cosmos. The telescope has been sending us, one after another, excellent images of the cosmos observed from the outside of the earth's atmosphere.

[ previous ]
[ next ]

top page