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marcus

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## Main Question or Discussion Point

This is an intriguing suggestion from John Baez in the Usenet

archive at cornell

http://www.lns.cornell.edu/spr/1999-12/msg0020466.html

I've been fascinated by this idea and have never been sure how to take it. Is it serious or just a passing fancy? what do you think? Have you heard other people besides Baez propose that area might be more fundamental in some sense?

Exerpt from Baez post:

[[...To understand why, note first that

in the usual Planck units, the Planck length is sqrt(G hbar / c^3)

When you see a square root, it's often a hint that some simpler

idea without a square root is lurking around the corner! This

suggests that perhaps more fundamental than the Planck length is

the "Planck area" G hbar / c^3

And, lo and behold: in loop quantum gravity, area turns out to be

more fundamental than length! Spin network edges give area to

surfaces they poke through, and area is quantized. A spin network

edge labelled by the spin j gives an area equal to sqrt(j(j+1)) times

8 pi G hbar / c^3 to any surface it pokes through...]]

He seems to be suggesting that a certain area could be considered a fundamental constant, namely the area

Ghbar/c^3

or else the area which is 8pi times that, hardly matters which

I should think.

Has anyone come across this area in coursework or research and formed any impression of it? Apparently it is prevalent in loopquantumgravity. But that is only one context and it would be nice to know of it surfacing in others.

There is one nice thing that impresses me about it. It is an algebraically simple combination of those 3 constants G, hbar, c.

Other Planck quantities tend to be comparatively more complicated to write----involving square root or else higher powers. Like the force unit involves the fourth power and the time unit involves the square root and the fifth power. So G hbar/c^3 is really pretty simple and easy to remember by comparison, if you care about conceptual ease and stuff like that.

archive at cornell

http://www.lns.cornell.edu/spr/1999-12/msg0020466.html

I've been fascinated by this idea and have never been sure how to take it. Is it serious or just a passing fancy? what do you think? Have you heard other people besides Baez propose that area might be more fundamental in some sense?

Exerpt from Baez post:

[[...To understand why, note first that

in the usual Planck units, the Planck length is sqrt(G hbar / c^3)

When you see a square root, it's often a hint that some simpler

idea without a square root is lurking around the corner! This

suggests that perhaps more fundamental than the Planck length is

the "Planck area" G hbar / c^3

And, lo and behold: in loop quantum gravity, area turns out to be

more fundamental than length! Spin network edges give area to

surfaces they poke through, and area is quantized. A spin network

edge labelled by the spin j gives an area equal to sqrt(j(j+1)) times

8 pi G hbar / c^3 to any surface it pokes through...]]

He seems to be suggesting that a certain area could be considered a fundamental constant, namely the area

Ghbar/c^3

or else the area which is 8pi times that, hardly matters which

I should think.

Has anyone come across this area in coursework or research and formed any impression of it? Apparently it is prevalent in loopquantumgravity. But that is only one context and it would be nice to know of it surfacing in others.

There is one nice thing that impresses me about it. It is an algebraically simple combination of those 3 constants G, hbar, c.

Other Planck quantities tend to be comparatively more complicated to write----involving square root or else higher powers. Like the force unit involves the fourth power and the time unit involves the square root and the fifth power. So G hbar/c^3 is really pretty simple and easy to remember by comparison, if you care about conceptual ease and stuff like that.