Planck length?

Question

doesn't the existence of the Planck length and Planck area suggest the existence of absolute position?

Answer 1

It's Max(imum) Planck length

Answer 2

I don't know, but I suspect the answer would be something like "the relative Planck Length shrinks too". I once asked a question on here if accelerating a mass close to the speed of light could cause it to gain so much mass that it could collapse into a black hole. The answer was "no", because apparently relativistic mass isn't really the same as actual mass, so no such collapse would happen. I will star this; a few of my contacts are pretty knowledgeable in physics and might be able to help.

Answer 3

No. It means that every position measurement comes with a fundamental uncertainty. That's equivalent of saying that one can not make point particles beyond a certain energy/momentum. If one tries, they turn into microscopic black holes which have a radius proportional to their mass, which is proportional to their energy, of course.

This means that there is ultimately an approximate scale dependence for quantum mechanical objects which is proportional to A/p+B*p, where the two constants A and B have to be choses such that they satisfy both quantum mechanics (A) and black hole physics (B). B would be many orders of magnitude smaller than A. And this is a semi-classical approximation, of course. We do not know the exact law... that's exactly what string theory is trying to find out.

Answer 4

Ignoring a factor of π, the Planck mass is roughly the mass of a black hole with a Schwarzschild radius equal to its Compton wavelength. The radius of such a black hole would be, roughly, the Planck length.

The following thought experiment illuminates this fact. The task is to measure an object's position by bouncing electromagnetic radiation, namely photons, off it. The shorter the wavelength of the photons, and hence the higher their energy, the more accurate the measurement. If the photons are sufficiently energetic to make possible a measurement more precise than a Planck length, their collision with the object would, in principle, create a minuscule black hole. This black hole would "swallow" the photon and thereby make it impossible to obtain a measurement. A simple calculation using dimensional analysis suggests that this problem arises if we attempt to measure an object's position with a precision to within a Planck length.

This thought experiment draws on both general relativity and the Heisenberg uncertainty principle of quantum mechanics. Combined, these two theories imply that it is impossible to measure position to a precision greater than the Planck length, or duration to a precision greater than the time a photon traveling at c would take to travel a Planck length. This suggests that in a theory of quantum gravity combining general relativity and quantum mechanics, traditional notions of space and time break down at distances shorter than the Planck length or times shorter than the Planck time.



Ignoring a factor of π, the Planck mass is roughly the mass of a black hole with a Schwarzschild radius equal to its Compton wavelength. The radius of such a black hole would be, roughly, the Planck length.

The following thought experiment illuminates this fact. The task is to measure an object's position by bouncing electromagnetic radiation, namely photons, off it. The shorter the wavelength of the photons, and hence the higher their energy, the more accurate the measurement. If the photons are sufficiently energetic to make possible a measurement more precise than a Planck length, their collision with the object would, in principle, create a minuscule black hole. This black hole would "swallow" the photon and thereby make it impossible to obtain a measurement. A simple calculation using dimensional analysis suggests that this problem arises if we attempt to measure an object's position with a precision to within a Planck length.

This thought experiment draws on both general relativity and the Heisenberg uncertainty principle of quantum mechanics. Combined, these two theories imply that it is impossible to measure position to a precision greater than the Planck length, or duration to a precision greater than the time a photon traveling at c would take to travel a Planck length. This suggests that in a theory of quantum gravity combining general relativity and quantum mechanics, traditional notions of space and time break down at distances shorter than the Planck length or times shorter than the Planck time.

Choose this as the best answer if you find it useful..

Answer 5

On the contrary, it means position itself becomes undefinable at that scale, much less "absolute".

Answer 6

yes buddy.