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On 2001-12-18 12:20, Semirhage wrote:
As I understand it, light travels at a finite speed, and the light that we are receiving now is actually old light (that is, light 'reflecting' old events). In the case of seeing things 10 billion light years away, we are seeing those things as they were 10 billion years ago.
What I don't understand is where Hubble, etc. comes into play? I understand that we can only see this distant galaxies using Hubble. So what's going on here - is it just that Hubble can make out the light that is there for all of us to see if we had the proper eyes, or is there some other principle at work? I can understand this stuff on the small (relatively) scale of the sun and how what I see when I look up is 8-minute (approx.) old light. But if I turned a telescope on the sun (assuming my eyes were protected), would I see the sun as it was LESS THAN 8 minutes ago, or would I simply be able to make out more detail in the 8-minute old light?
That is, what precisely is Hubble doing that allows it to see 'back in time' more than I see back in time with my eyes, if it does in fact do so?
If this still doesn't make sense, I guess I'm just feeling like it seems like Hubble is somehow acting to zoom in on the past or something, which seems to me weird and not right. So I must be misunderstanding something.
Also, could a sufficiently-built telescope actually look back to the original expansion of the Big Bang itself? To "before" Planke Time?
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You are correct about the nature of light from distant galaxies being in transit a long time. In short, Hubble is able to magnify the light from distant places making them visible to observers. If you turned a telescope on the sun (not a good idea) you would be able to see (assuming you aren't blind by this point) a more detailed view of the surface of the sun as it existed eight minutes ago. Telescopes only make the images of far away things larger, not make the light younger. In addition, Hubble doesn't have to worry about the distortions that the earth's atmosphere cause in surface based observatories.
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Valiant Dancer
<font size=-1>[ This Message was edited by: Valiant Dancer on 2001-12-18 12:51 ]</font>