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Originally posted by fourthmeal
reply to post by NewAgeMan
imagine.gsfc.nasa.gov...
cosmology.berkeley.edu...
Because visible light output drops by a factor of 4 for every doubling of distance. And we are a LOOONG way away from any of those stars.
And the atmosphere blocks a bit of light too.
Originally posted by Arbitrageur
Actually Olber's paradox assumes an infinite number of stars.
Originally posted by elfie
Olber's paradox
A technical explanation.
The inverse square law, as stated above, is also a good explanation.
A simpler solution to Olber's paradox is that the number of stars is huge, but finite.
I have never seen this as much of a paradox with a finite number of stars. Some galaxies are so distant that one photon arrives at your eye every few seconds. The light is hitting your eye but that's not intense enough for your eye to detect it.
Simple.
Originally posted by NewAgeMan
However, if you took the Hubble Space Telescope and created a wrap around image enveloping the earth at every point of the sky, and at variying magnifications, what would be seen would not be a black sky dotted with stars, and a hazy river-like Milky Way in one section, or even a nebula here and a galaxy there, with black space in between - but a dome of nothing BUT stars and galaxies without any black in between whatsoever!
Thus, even though we cannot see it with our eyes, seeing "only" the local stars in a very very small sphere of space within the Milky Way Galaxy, what's mind-numbingly AWESOME is that in truth, the whole sky IS "bejeweled" every single point of it, all around the whole earth - think of that next time you look at the sky either during the day (imagining what's behind the blue) or during the night (what's in between the stars that are visible).
The Hubble Deep Field image suggests to me that this is NOT the case.
Originally posted by NewAgeMan
If anything the "point" I'd like to highlight is that every point in the sky encircling our world, is filled with stars and galaxies - is it bejeweled the entire sphere or dome surrounding the earth.
It's a DARK patch of sky. If you look there with your eye you see almost nothing. Even with Hubble's super-huge light gathering capability compared yo your eye, and even with a super-long time exposure, it's still mostly black. I think the idea that it's full of light is a mental construct in your mind that's not supported by photographic evidence in reality, and what light exists is so faint we can't see it.
Originally posted by NewAgeMan
The Hubble image is of a dot of sky the size of a square milimeter held at arm's length.. take that point and add the other 10 or 100 million such points which encircle the globe and you'll start to get the picture in terms of what I mean by "bejeweled".
Originally posted by ErosA433
Well theory goes, if you believe in the hot big bang (personally i think its the best and most supportive of observational data that we have,, but yep please explain any others to me, I have a masters in Physics and Astronomy and a PhD in physics, and unlike alot of people would say of an academic, i do find theories very very interesting) that as the universe expanded (remember it is an expansion of space, not an expansion in space) the environment was at ultra high energy and what existed was a soup of exotic particles... quark sea people have postulated.
As the universe expanded the energy density reduced until eventually stable matter 'condensed' out of high energy gamma rays. Now there is an issue about how this happens, it would produce equal amounts of matter and anti-matter. However the theoretical fix for this is CP violation in the quark and lepton sectors... it has been observed in the quark and there have been hints in the leptons...
So when this condensation happened, it represents the point at which the universe switched from being photon dominated, and matter dominated. Photons do remain from this process... these are redshifted down from being high energy gamma rays to a couple of kelvin energy microwaves. If you look at the night sky in microwave, you do indeed see a constant glow everywhere, it is in fact extremely uniform as you expect.
On objects that are far away at the edge of what you see... well these objects are probably made up of super massive stars, the early galaxies that formed would probably have contained very dense gases compared to what we see now. Stars that are big, are very short lived also... so the early universe would have been a mix of supermassive stars forming and going nova, along with smaller red stars that probably still exist today, slowly burning away their fuel.
The sun is a second or maybe third generation star, and is actually quite unusual as is one of the heaviest 5% of all stars in the galaxy.
Furthermore, you cannot look in all directions in the optical, we are blocked off by dust when we look towards the galactic centre, we have no idea what is behind it really.
Originally posted by fourthmeal
reply to post by NewAgeMan
imagine.gsfc.nasa.gov...
cosmology.berkeley.edu...
Because visible light output drops by a factor of 4 for every doubling of distance. And we are a LOOONG way away from any of those stars.
And the atmosphere blocks a bit of light too.