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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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.