Your favourite Paradox

Olbers Paradox, it's an argument which refutes the notion that the Universe is infinite and thus must be finite instead. The paradox goes as follows: if the universe is infinite then there should be infinite stars and therefore you should see light from any possible angle. Question: If we should see light at all times, why is it dark at nights?

Let's all try to share abit of knowledge so that we can all grow. What is your favourite paradox? it can be anything from maths to physics to philosophy itself.

Also please try to give a very brief explanation of the paradox if you understand it.

I start;




Video: http://youtu.be/aH2fpmxMV4Q

Correct me or any other user if the explanation of the paradox is wrong.

none of the stars except the sun is close enough...maybe?

it doesn't matter how close an object is, light still travels from far distances.

it doesn't matter how close an object is, light still travels from far distances.

Seems like an incorrect paradox. Just because the universe is infinite it doesn't mean the space must be infinitely filled. Also; there are things in the way of stars (gas etc.), and missing that we can see stars right now; but that doesn't mean it's bright (intensity decreases when the light source is further).

Basically that's not a paradox and more a person who doesn't know anything about physics (unless I'm missing something obvious).

I always liked .99 recurring =1 was good, basic but good. I mean, it isn't but it is.

That's not really a paradox, it's just a mathematical convention. The best way to think about it is looking at how the difference between .99.... and 1 varies as you keep adding more 9s. The difference keeps getting smaller and smaller, and so if you tend the amount of 9s to infinity (which is what recurring means) then the difference tends to zero (i.e. they are equal)

Yes, it does travel from far distances, but the measured intensity is inversely proportional to the distance between the source and the observer squared (assuming uniform radiation in a vacuum)

Seems like an incorrect paradox. Just because the universe is infinite it doesn't mean the space must be infinitely filled. Also; there are things in the way of stars (gas etc.), and missing that we can see stars right now; but that doesn't mean it's bright (intensity decreases when the light source is further).

Basically that's not a paradox and more a person who doesn't know anything about physics (unless I'm missing something obvious).

In addition, the light from stars further away takes longer to reach us, so if they're infinitely further away they'll take an infinitely long time to reach us.

Yeah. Not keen on that paradox.

I do understand it. I look at it like folding paper in half again and again and so on till there's nothing left. But in theory, there must always be somthing no matter how small, right? (or not?)

By the way, hassi, Olber was an astronomer I think he knew much more about physics than you do...

I wouldn't shouldn't have stated that infinite stars must exist, finite stars would do. Have any of you even watched the video explaining it? It answers all of the you guys have raised.
By the way, hassi, Olber was an astronomer I think he knew much more about physics than you do...

Well that's not entirely true, Olber was a 19th century astronomer, which means he was around long before special reletivity (which gives a limit to the radius of the observable universe) plus I'm sure there'll have been a few more discoveries since his time that explain away his paradox

That's the problem with trying to find real world analogues to mathematical problems involving infinities. In real life, eventually you wouldn't be able to fold it anymore due to the paper having a finite thickness (in fact, you can't fold that many times, due to the thickness increasing exponentially with the number of folds) and if you used cutting instead of folding eventually you'd reach the size of it's elementary particules and again wouldn't be able to continue.
Unfortunately it's very very difficult to imagine infinities, which is a shame.

Fair enough, maybe the real life analogy was not such a good idea. Still though, no matter how many 9's you have past the decimal point, there will be one more 01 if subtracted from 1. . .I think

Just seems quite poorly written at least; I doubt those were Olber's exact words and justification.

But if we're talking about stars infinitely far away then the light intensity provided tends to zero (1/r^2). Depends how many stars there are in comparison to the distance (i.e. which infinity is 'bigger').

Also what I said about blocking out light due to gas etc. is actually the solution to the 'paradox' given that current physics understanding is correct.

"An alternative explanation is that the universe is not transparent, and the light from distant stars is blocked by intermediate dark stars or absorbed by dust or gas, so that there is a bound on the distance from which light can reach the observer.
This would resolve the paradox given the following argument: According to the second law of thermodynamics, there can be no material hotter than its surroundings that does not give off radiation and at the same time be uniformly distributed through space, however there is no mathematical formula proving that light energy is absorbed infinitely and not radiated, especially by already highly heated particles of gas in a near vacuum. Energy must be conserved, per the first law of thermodynamics and it can be transformed. Therefore, the intermediate matter would not necessarily heat up or glow and the energy (possibly at different wavelengths) would dissipate in infrared radiation and various diffracted light shifted towards red. This would not result in a paradox if current physics understanding is approaching the truth."


So yes Olber may have been an amazing astronomer but I am using justification from more recent science that is believed to be more correct.

Well now because it's impossible to have 0.0000000 infinitely then a 1. That implies there is an end, but there is not.