I thought this as well. The answers seems very obvious, so I began to wonder if I’m missing something and it’s actually not obvious.
Yet even if the dust was mostly local, it would still block out light from infinity. Assuming it’s thick enough. But presumably the dust wouldn’t only be local; it could even be worse in other parts of the universe. Essentially we just don’t live in a perfect vacuum. There’s a bunch of crap blocking the light.
I suppose at some point in the history of the universe, there was probably less dust and it actually was much brighter.
The problem with dust is that in an infinite universe, the dust would have to absorb so much light that it would become so hot that it would glow, eventually just as bright as the stars.
Oh, so my guess actually is naive then. But is it true that it would have to glow? Could it not depend on the ratio of light to dust, so to speak? Or is it inevitable that the dust would always eventually increase in heat until it glowed?
Sorry for the belated answer - but yes, it is inevitable. Black body radiation means everything in the universe glows.
This whole thing is just a problem with an universe both infinite and old, though. In a young universe, the dust might still be cold enough (yet still hotter than it is in reality), and in a finite universe, there could be a steady state as you described.
Better still, in a young expanding universe (that still may yet some day contract) the visible horizon includes less than it once did as the mean distance between matter has increased.
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Because of stellar dust? I'm not sure what makes this a paradox. There's a well-known explanation.
I thought this as well. The answers seems very obvious, so I began to wonder if I’m missing something and it’s actually not obvious.
Yet even if the dust was mostly local, it would still block out light from infinity. Assuming it’s thick enough. But presumably the dust wouldn’t only be local; it could even be worse in other parts of the universe. Essentially we just don’t live in a perfect vacuum. There’s a bunch of crap blocking the light.
I suppose at some point in the history of the universe, there was probably less dust and it actually was much brighter.
The problem with dust is that in an infinite universe, the dust would have to absorb so much light that it would become so hot that it would glow, eventually just as bright as the stars.
Oh, so my guess actually is naive then. But is it true that it would have to glow? Could it not depend on the ratio of light to dust, so to speak? Or is it inevitable that the dust would always eventually increase in heat until it glowed?
Sorry for the belated answer - but yes, it is inevitable. Black body radiation means everything in the universe glows.
This whole thing is just a problem with an universe both infinite and old, though. In a young universe, the dust might still be cold enough (yet still hotter than it is in reality), and in a finite universe, there could be a steady state as you described.
Better still, in a young expanding universe (that still may yet some day contract) the visible horizon includes less than it once did as the mean distance between matter has increased.
I think it's because the expansion of the universe is happening faster than the speed of light. So the light from the far regions can never reach us.
The universe could well be infinite, but the Hubble volume is pretty much finite...
If it was only dust, it alone would not explain the darkness due to re-emission of light (as other commenters pointed out).