Olbers' paradox: why is the night sky dark?

Started Nov 12, 2012 | Discussions thread
Jonny Boyd Forum Member • Posts: 89
Re: Olbers' paradox: why is the night sky dark?

I seeyou still havent found any flaws in my mathematics. I assume then that you agree that the calculations are flawless and the inverse square law does indeed result in seeing a bright sky in Olbers' Paradox. So glad to see that you now agree with me, which we clearly do since you can't find anything wrong with my maths.

trisd wrote:

Jonny Boyd wrote:

As i've repeatedly said, the shells have equal luminance and flux.

Stop hallucinating already. The paradox is about BRIGHTNESS.

Brightness is anambiguous term. To cover all the bases I gave answers for various ways of measuring brightness. 'They' are referring to luminance And flux. this can be seen at webpages like this: http://www.h2g2.com/approved_entry/A765029 And as I said, each shell does indeed have the same luminance and flux.

They say:

- "...if you look at a shell twice as far, each star is only a quarter as bright, but there are four times as many stars, so each shell is equally bright."

Here are two such shells as they describe, and both of the two images did receive the same total amount of light from each shell, but that does not mean they would appear equally bright to human eyes. What part do you still not understand?

No one has ever claimed that individual shells would look identical (though when you consider shells sufficiently far away, they would indeed look identical). Olbers' paradox concerns the appearance of the sky, which is made up of infinite shells combined, not just two considered individually.

The distribution of light in individual shells varies, but that is somewhat irrelevant.

Stop hallucinating. Human eyes do not see total amount amount of light summed up in a single value, but they see distribution of that light, and thus that is not only relevant, it is all that matters. The paradox is about BRIGHTNESS. Do you understand?

You appear to be the one hallucinating as you are arguing against a point I've not made. As I've said before, my calculations provide brightness values for every point in the sky and they are all the same value. Do you understand the mathematics or are you simply mindlessly repeating phrases?


Federal Standard 1037C, the Federal Glossary of Telecommunication Terms - brightness:
- An attribute of visual perception in which a source appears to emit a given amount of light

Whoopdeedoo. If every photoreceptor in your eye or your camera records the same luminance then you will perceive uniform brightness. That is what all the calculations show will happen. I've given you the calculations on many occassions And you can find the gist of it on this page that the Wikipedia article links to: http://math.ucr.edu/home/baez/physics/Relativity/GR/olbers.html

Olbers' paradox doesn't say that each shell will have a uniform distribution of light, but that the light of the night sky i.e. when you view all the shells together, will be uniformly distributed.

Wrong. They say: - "...if you look at a shell twice as far, each star is only a quarter as bright, but there are four times as many stars, so each shell is equally bright."

That doesn't contradict anything I said. Equally bright means equal luminance or flux, not same distribution of light.


Well duh. I've said that myself plenty of times. Each shell has the same luminance and flux. Who exactly is disputing that?

Read, stop hallucinating. The conclusion was obviously reached when considering only two shells individually, and has nothing to do with their combination or any other shells. Do you understand?

Two shells are used to show that brightness is independent of diatance. The result for two is then extrapolated for infinite shells. a basic understanding of English would make that clear:

'However, the second shell is twice as far away, so each star in it would appear four times dimmer than the first shell. Thus the total light received from the second shell is the same as the total light received from the first shell.

Thus each shell of a given thickness will produce the same net amount of light regardless of how far away it is. That is, the light of each shell adds to the total amount. Thus the more shells, the more light. And with infinitely many shells there would be a bright night sky.'

The above is from the Wikipedia article you love so much. It as abundantly clear that is says that with infinitely many shells, the sky would be bright and that the conclusion is reached by assuming that each of those infinite shells behaves like the two example shells in so far as they have equal luminance.

It's also obvious that they're talking about more than two shells because they refer to what the eye sees and the eye sees all the shells together, not individually.

Another way of calculating what those shells look like together has been given to you many times but you refuse to look at it. If you're still convinced that I'm wrong and you're some genius physicist then you would very quickly shut me up by finding a flaw in those calculations. The longer you go without doing that though, the more obvious it becomes that you don't understand either the mathematics or the physics.

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