So why does it get dark at night? Is it as simple as the Sun being on the other side of the Earth? No. The real question is: how old is the universe? Is it infinitely old, as some assume? Since the sky is dark at night, it can't be.
The sky is dark at night because the universe has a finite age. It has a finite age because there are a finite number of stars, and the light from these stars is only just reaching us. If the universe was infinite and infinitely old, there would be an infinite number of stars in the sky, and there would have been an infinite amount of time for the light from all of them to reach us; the sky would never go dark. There would always be enough light.
Embarrassingly, this was the first question I've asked of the wondir community, and I forgot to correctly set its category - it now resides in the Beauty and Fashion section, so perhaps I should not have been surprised by the answers I got. It was great to see such a rapid response though - four replies in as many minutes.
1 comment:
Allen, thanks for the comment. I don't use an IM at work, but I did receive notification of the answers by email, which is fine for me. Thanks also for the tip about the atom feed; for anyone interested, there is a feed for the site, though how well it works is hard to say as I don't have a reader yet. Also, my posts tend to be long and involved, which will probably count against me in terms of casual readership, though I don't know how long blogs are regarded in the rss community.
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