# Olbers' paradox: why is the night sky dark?

Started 6 months ago | Discussion thread
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 Re: Olbers' paradox: why is the night sky dark? In reply to trisd, 5 months ago

trisd wrote:

Jonny Boyd wrote:

As I've told you plenty of times, you need to define what you mean by 'BRIGHTNESS.' That's what we did in the last couple of posts, yet here you are reverting to a word without a clear definition. How is anyone supposed to communicate with you if you won't define words?

Oh, so you don't understand what Olbers' paradox is talking about when it muses how dark or bright the night sky would look like.

And you also don't understand what it means when they say stars at double the distance are four times less bright, that is four times dimmer.

As a physicist, I understand far better than you do and have tried to explain things for your benefit. I've done it lots of different ways.

I've shown you pictures: http://forums.dpreview.com/forums/post/50337374

I've given you equations: http://forums.dpreview.com/forums/post/50317948

I've done step-by-step calculations for you: http://forums.dpreview.com/forums/post/50349143

I've given you numeric examples to illustrate what this looks like: http://forums.dpreview.com/forums/post/50397931

But you ignore the pictures, decried the equations as irrelevant, had no answer to the calculations and haven't even acknowledged the example. When I have answered your questions so many different ways and got no response except 'do you see two equally-bright shells,' then really what reason is there for me to talk to you? Whatever I say, whatever attempt I make to help you udnerstand, you just ignore. Perhaps all I should do then is ignore you?

Well, if you do understand then you should know what NASA meant when 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 same "brightness" is what I am asking you about. So, again:

- Do you see two equally bright star-shells on these two images bellow? YES/NO

As i've said on numerous occasions, YES. I agree with NASA and all the universities and all the physicists who say that the shells have the same brightness and that the inverse square law by itself does not explain Olbers' paradox.

Or as I've put it in another post:

'If you're asking about the total brightness of the two images, then yes, they are the same. If you're asking about the average brightness of a unit area, then yes they are the same because the total amount of light and the area are bith the same. If you're asking if the distribution of light is the same, then no, obviously not. But if you add all the shells together then you end up with a unifrom distribution. Olber's paradox says nothing about whether the individual shells have uniform distribution of light.'

Why do you keep asking a question I have answered for you many, many, many times, while simultaneously ignore everything I say? My patience is finally wearing out and unless you actually interact with what is being said rather than parroting the same question over and over, it seems that the best advice I can give you is to get your parents to take you to see an educational psychologist and have yourself assessed. You could probably do with quite a bit of help in school if the problems you have here are in any way representative of how you're getting on in the real world.

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