31–40 of 55 posts
Earlier quoted context omitted.
> The redshift hypothesised in the Big Bang model [...] Doesn't sound to me like it's more than a hypothesis, but I could be wrong.
Well redshift alone explains the paradox. You don't even need to accept the big bang theory. You can just say "stars that are further away are more redshifted" and that alone explains this. Which we know is true. That's not a hypothesis, redshift can be observed directly. And that fact alone explains the apparent paradox. The most distant stars are redshifted away. To quote the above article >The redshift hypothesise…
So basically, we don't exactly know why the night sky is mostly dark? (At least, that's what I got out of this)
What we know is that an infinitly old and large universe is not possible given our understanding of physics and the sky being dark at night. That's all.
Is there a good explanation as to why this paradox isn't explained by universal expansion? From wikipedia: "To any observer in the universe, it appears that all of space is expanding, and that all but the nearest galaxies (which are bound by gravity) recede at speeds that are proportional to their distance from the observer."; Wouldn't this imply that, there was probably a time in the distant past when the night sky…
I don't know how all of the factors you bring up interact, but as far as the last point: the universe is indeed uniform and isotropic at a large enough scale (~300 million ly), called, nicely enough, the End of Greatness ( https://en.wikipedia.org/wiki/Observable_universe#End_of_Gre... ).
Obviously, supervoids are a part of universal uniformity, at a large enough scale, but I'm having a hard time rectifying that the scale we're talking about is ~300M ly, and not significantly larger, with the fact that there are, trivially, a large number of "300M ly windows" one could pick, anywhere in the universe, and see extremely different things. In some cases, an extreme density of billions of galaxies, and in others a number that is dwarfed by even the number of large bodies in our own solar system. Is this a situation where we just didn't know about these 300M+ ly superstructures when that scale was calculated, and it needs to be revised? Or we knew about them, the math would naturally allow for a level of deviation, and to this day they're still rare and small enough that the deviation is low? Or is there something about the math I'm missing whereby discovering any number of these, into the future, still allows that ~300Mly number to work?
More to read, I do believe.
So basically, we don't exactly know why the night sky is mostly dark? (At least, that's what I got out of this)
The paradox itself is that if the universe is both infinite and eternal then we shouldn't have a dark sky. This is 'trivially' solved by demonstrating that either of those conditions aren't true. The article opts to use the explanation given by Edgar Allan Poe to demonstrate this, which is that the universe has a finite age and the speed of light is finite so there's only a finite amount of observable universe, which…
I've never really felt like I understood the paradox, since the way people explain it, it sounds to me like they're just denying the idea that an infinite sum can have a finite value.
Like, why couldn't the brightness of the sky in an infinite universe be any value at all, depending on the density?
The argument against an infinite universe that makes sense to me is that it would collapse on itself. But as a thought experiment, the stars could be massless and/or fixed in place.
Earlier quoted context omitted.
What we know is that an infinitly old and large universe is not possible given our understanding of physics and the sky being dark at night. That's all.
An infinitely large observable universe is not possible, however an infinitely large and infinitely old universe is still possible with dark sky at night.
If the universe is infinitely large and old, and light works as well believe it does, then light should come from all directions. That's the entire point of this paradox.
Light as we know it moves without limit. If anything is blocked by it, the blocking object would heat up until it glowed just as brightly.
Earlier quoted context omitted.
An infinitely large observable universe is not possible, however an infinitely large and infinitely old universe is still possible with dark sky at night.
Howso? If the universe is infinitely large and old, and light works as well believe it does, then light should come from all directions. That's the entire point of this paradox. Light as we know it moves without limit. If anything is blocked by it, the blocking object would heat up until it glowed just as brightly.
Black holes say no.
Earlier quoted context omitted.
An infinitely large observable universe is not possible, however an infinitely large and infinitely old universe is still possible with dark sky at night.
Howso? If the universe is infinitely large and old, and light works as well believe it does, then light should come from all directions. That's the entire point of this paradox. Light as we know it moves without limit. If anything is blocked by it, the blocking object would heat up until it glowed just as brightly.
Or, more precisely, an infinite number of stars spread out rather uniformly.
Assuming an infinite amount of anything seems to be a good way to end up with a paradox.
Earlier quoted context omitted.
I don't know how all of the factors you bring up interact, but as far as the last point: the universe is indeed uniform and isotropic at a large enough scale (~300 million ly), called, nicely enough, the End of Greatness ( https://en.wikipedia.org/wiki/Observable_universe#End_of_Gre... ).
Its confusing to me that this would be the case, when the Bootes Void alone is ~330M ly in diameter; and that's small. The Canes Venatici Supervoid is upward of 1300M ly in diameter; the LOWZ North 13788 void is potentially as large as 3000M ly; the list goes on. We've detected over 100 of these supervoids larger than the "End of Greatness"; and that's just what we've seen so far. Obviously, supervoids are a part of…
I think you might be overestimating how dense a galaxy is, in the grand scheme of things. You may think it's a long way down the road to the chemist's, but it's still almost entirely empty space.