[OT] Power over radio is it a true thing or just a myth ?

[Oleg Goldshmidt]

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 Goldshmidt | oleg at goldshmidt.org