Olbers' paradox: why is the night sky dark?

Started Nov 12, 2012 | Discussions thread
Jonny Boyd
Forum MemberPosts: 89
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Re: Olbers' paradox: why is the night sky dark?
In reply to trisd, Dec 2, 2012

trisd wrote:

Jonny Boyd wrote:

I have a physics degree from Oxford...
...isn't it in your interest to expose the flaw in my mathematics?

If you put it that way, then yes.

You are contradicting yourself here:

4.) each pixel will have one of these stars
5.) these stars will only occupy half a pixel

That's not a contradiction. Each pixel that does not have its line of sight blocked by a star from the 1r shell will see one star star from the 1.41r shell. This star will occupy half of each pixel, leaving half a pixel for stars from the 2r shell. There is no contradiction there.

...and you don't seem to realize how your math actually looks like.

In first row there is your close shell, middle shell, and both of them combined. In second row there is your middle shell, far shell, and both of them combined. In third row there is your close shell, combined middle and far shell, and finally at the bottom-right is all of them combined.

Your picture is wrong. The images in the topright and bottom right are wrong. You've increased the brightness of the stars from the 1r shell. Remember that the 1r stars are large enough to occupy one pixel, so those pixels will not get brighter.

I'm especially surprised to see you making that mistake when you've been so insiatent about the effect of stars blocking others. Light can'trravel through stars. What it can do it heat stars up so that they glow brighter, but the effect of one shell would be incredibly small and if you're taking that into account then you need to model the effect of an infinite number of shells.

Basically, if you're going with the simple model of stars blocking light and not heating up as a result, then your picture is wrong because you've made the 1r stars brighter. If you were intending to model that edfect then your picture is wrong again because you haven't modelled the impact of infinite shells. eirher way, it's wrong.

My calculations were based on the simple model, Incidentally and result in all three squares in the right column being the same as the square in the middle of that column. If you think I'm wrong then show me the flaw in the mathematics. You should probably stop drawing pictures though because they tend to be wrong, largely because you haven't done the necessary maths beforehand.

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