Re: How can the Planck length be claimed to be the smallest length?

On May 15, 5:51 pm, donjstev...@xxxxxxx wrote:
On May 7, 11:07am, Igor Khavkine <igor...@xxxxxxxxx> wrote:



On May 7, 9:20 am, JohnMS <john_m_stan...@xxxxxxxxxxx> wrote:

String theory is often claimed to have a minimum length
(the Planck length or near it), so does loop quantum gravity,
so do many other approaches. The theory-independent approaches
argue convincingly that lengths below the Planck length
cannot be measured by any known procedure or device.

Unfortunately, neither string theory nor loop quantum gravity enjoys
the status of an experimentally verified theory. The theory-
independent approaches are precisely the ones that use dimensional
analysis, as discussed previously by J. J. Lodder and myself.

The electron mass is also well known, and
R=2GM/c^2 is not in doubt, as electrons
have gravitational effects. It seems difficult to say
that R=2GM/c^2 is wrong
for electrons.

What would it mean for the above paragraph to be wrong? You've defined
a length scale R. You can write down any length you want and call it
R, no-one will argue with you solely on that basis.

So in practice there IS a paradox, because
electrons are known experimentally to
have a gravitational length smaller than the
Planck length.

I see. And what is this experiment that has measured the gravitational
length of the electron? None of the modern particle physics
experiments have probed lengths that are even withing a few orders of
magnitude from the Planck length, not to mention beyond it.

Hope this helps.

Igor

Hi Igor; Some photon wavelength equations relate the Planck length to
the electron mass.

L1/L2 = L2/L3

L1 = (L2)^2 (1/L3) = 2pi (3/2)^1/2 (Planck length)

Where L2 is the photon wavelength with energy equal to the mass energy
of one electron plus one positron
and the wavelength L3 is (2pi)^2 (c)(one second).

so, if human beings decided to use a different unit of time than a
second, L3 (and then L1) would come out to be a different physical
value?

i have trouble imagining that physical reality gives a rat's ass what
unit of time we humans happen to use. or the aliens on the planet
Zog.

r b-j

.

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