The Planck length and string theory

[john t]

String theorists frame much of their studies in the context of Planck length. The theories are meant to fold together QM and general relativity. The equation for Planck length includes the gravitational constant, G. It seems to me the theorists are assuming the gravitational laws extend to the sub-Planck length and are trying to force the conclusions along those lines. Is this considered justifiable by physicists/mathematicians?

John Thompson

<< Mentor Note: personal e-mail address deleted >>

 

[Vanadium 50]

. It seems to me the theorists are assuming the gravitational laws extend to the sub-Planck length and are trying to force the conclusions along those lines.

Why do you think this is what they are doing?

 

[john t]

Why do you think this is what they are doing?

Brian Greene, in his book "The Elegant Universe" couches all the arguments around the Planck Length. He is a physicist/mathematician at Columbia U.

 

[weirdoguy]

And this book is not a textbook, so you can't draw any conclusion from that. Pop-sci books are made for entertainment, if you want to really learn something you have to use textbooks.

 

[cosmik debris]

The Planck length defines a length scale, this in turn, because of the units used, defines an energy scale. At these very short distances new physics is thought to come into play and the gravitational effect becomes comparable to the other forces. I know this is waffling but you haven't received much of an answer so far, so this will give people something to argue about. :-)

Cheers

 

[PeterDonis]

Brian Greene, in his book "The Elegant Universe"

Which, as has been noted, is a pop science book, not a textbook or peer-reviewed paper. So it's not a valid source for discussion here at PF.

If you want to support your claim about string theory you will have to find a valid source. In the meantime, this thread is closed.