[OT] How many dimensions? (WAS: Power over radio)

[Dotan Cohen]

2009/8/24 Oleg Goldshmidt <pub at goldshmidt.org>:
> I'll bite - it's OT, but too much fun to skip... ;-)
>
> 2009/8/24 Shachar Shemesh <shachar at shemesh.biz>:
>
>> As a side note - does that prove that our universe only has three
>> dimensions?
>
> Technically, no, though many philosophers (as opposed to physicists or
> mathematicians) will say it does. The number of dimensions does not
> follow from R^-2, but if you live in a 3D world then R^-2 follows...
> ;-)
>
> I have not checked every statement on
> http://en.wikipedia.org/wiki/Spacetime#Privileged_character_of_3.2B1_spacetime,
> but it does have useful pointers that I'd myself recommend.
> [disclosure: I *am* a physicist].
>
> The R^-2 character of gravity is arguably even more important than
> radiation, but the mathematical reason is the same.
>
> If you are interested in proving that our world is 3D then probably
> the most important set of physical/anthropic arguments that "derive"
> N=3 from the observable universe was proposed by Ehrenfest (and Weyl:
> Ehrenfest concentrated on gravity and Weyl on electromagnetism) in the
> early 20ies - a reference is in the Wikipedia article above.
>
> For those interested in an in-depth discussion of why the Universe is
> what it is I recommend "The Anthropic Cosmological Principle" by
> Barrow & Tipler (see the reference in the Wikipedia link) - it's big,
> but real fun to read, IMHO. Unfortunately, I don't have a copy and I
> can't recall from memory how much background it assumes.
>

Oleg, I understood that the universe has 11 or so dimensions, and that
5 or six can even be measured. But the wikipedia article that you link
to claims only 3+1. I have googled a bit but found only very technical
explanations, or baby facts with no explanations. Can you sum it up
for someone who is familiar with relativity, but is not a physicist?
Thanks.



-- 
Dotan Cohen

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