Do you or have you ever use thought experiments to some practical end?

  • qjkxbmwvz@startrek.website
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    2 days ago

    https://en.m.wikipedia.org/wiki/Olbers's_paradox

    Olbers’s paradox, also known as the dark night paradox or Olbers and Cheseaux’s paradox, is an argument in astrophysics and physical cosmology that says the darkness of the night sky conflicts with the assumption of an infinite and eternal static universe.

    The night sky being dark has some profound cosmological implications.

    • TerranFenrir@lemmy.ca
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      2 days ago

      The answer is very simple. Our universe is very likely not static. We already know that it is expanding (as of today). The further you look in space, the faster that space is moving from us. This causes more and more redshift of light the further you look away (the wavelength of light becomes longer and longer).

      Beyond a certain point, space moves faster than the speed of light. Thus, we get no light.

    • Opinionhaver@feddit.uk
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      2 days ago

      With the Hubble Deep Field, they pointed the telescope at a seemingly empty patch of night sky - and it turned out to be filled with distant galaxies. Also, light traveling from far enough away gets redshifted into the infrared range, which means it can no longer be seen by the human eye.

      • qjkxbmwvz@startrek.website
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        2 days ago

        Yes. But why is there an absence of light?

        If there are infinite stars, then every direction you look would encounter a star. (Things stay the same brightness per subtended angle as they get far away. Space dust doesn’t matter, as it would thermalize and radiate.)

        So, the universe can’t have infinite luminous matter, be static and ageless, because if it were then the night sky would look like the surface of a sun.

        This may all seem obvious, but it’s neat that you can figure that out with the naked eye.

        • Sludgeyy@lemmy.world
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          2 days ago

          Can’t we see stars that do not show up in the night sky? Like that spot looks dark to the naked eye, with a hobby telescope it looks dark, but with a space probe telescope you can see a distant star is there?

          You discounted space dust. But there has to be a near infinite amount of asteroids out there. If I wanted to see 1m lightyears into a specific spot, like the odds of not hitting an astroid would be pretty hard.

          Like if you had a Lite Brite globe with each Lite Brite peg representing a sun. In the middle of the globe it would be completely lit up. However, if you started throwing around astroids around inside the globe, you’d start blocking pegs. Suns, pegs, are still behind the astroid. It’s just blocking the light. A tiny astroid could cast a huge shadow. Even tiny space dust.

          • qjkxbmwvz@startrek.website
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            1 day ago

            You discounted space dust.

            No I didn’t — it would thermalize and radiate.

            This is not my paradox, and it’s not really a paradox at all, as the big bang model explains it nicely. There are many nice articles on the topic of you’d like to read more about it.

            • Sludgeyy@lemmy.world
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              1 day ago

              I’m not trying to disprove you or anything, I know it’s not your paradox. Apologies that it came off that way.

              But like a tiny flake of space dust is enough to eclipse a sun for us a near infinite distance away. Matter is not going to let light through it. Even if some space dust thermalizes and radiates. The chances something like an asteroid, planet, moon, etc. Is high. Space seems mostly void, but an infinite amount of mostly void is still a lot of stuff.

              I’ll check then out!