Comments on: Planck units (uselessness of).

By: andy findlay

andy findlay — Fri, 05 Dec 2008 14:46:36 +0000

According to FH theory the Planck Mass is the mass equivalent of the vacuum energy of the volume described by the planck length cubed.

1/G is the mass of 1 cubic meter of vacuum space.

Work it out yourself and you will see that this is true..

The derivation of this can either be done by using newtons gravitational laws (top down) or from the simple equation CT = R

The mass of any volume of vacuum space is given by M = Rcubed / (GxT squared) according to FH Theory….

By: LigImmemy

LigImmemy — Thu, 20 Nov 2008 13:49:14 +0000

Cool post, maybe you dream fof writters? ___________________________________ Sry, hehe))

By: Is the Newtonian constant G a scholastic form? « Force

Is the Newtonian constant G a scholastic form? « Force — Sat, 04 Oct 2008 10:49:24 +0000

[...] Plank units (uselessness of) [...]

By: Weldon Vlasak

Weldon Vlasak — Mon, 26 May 2008 13:17:08 +0000

It is not necessary to include the gravitational constant in order to manipulate Planck’s natural units (see http://www.science-site.net/plancksunits.htm). In fact, the gravitational constant is the most questionable natural unit. Planck’s approach was to work forwards and backwards with the four constants, setting them all at unity. The same thing can be done with three constants, and they all work out the exact values of Planck’s units. This eliminates the radical in all of the equations, and the limitations of the fuzziness of the gravitational constant. Therefore, it is not necessary to even consider gravity in the derivation of Planck’s constants, although he made that work out too. Try substituting modern constants, and you will find that they do not work out exactly, which was exactly what Planck sought to avoid. As he put it, “…these quantities retain their natural significance as long as the law of gravitation, and that of the propagation of light in a vacuum and the two principles of thermodynamics remain valid…”.

By: mark a. thomas

mark a. thomas — Sat, 10 May 2008 19:31:21 +0000

I’ve arrived at this post rather late but I’ve a few observations about this. It must be kept in mind that the Planck mass has context at or near the quantum gravity regime. The exception to this in the semi classical regime is where the inverse square of the Planck mass is the weak gravity condition of the normal Newton’s constant G. However, there is good reason to consider that G runs as you go up the scale toward the Planck energy and that it possibly hits a unity value. Again, emphasize that Planck mass only means something near the Planck density (in the compact space). After the semi classical gravity there would be quantum corrections to GR (as it is very close but not yet in the quantum gravity era). At the stage near, at Planck densities dimensionless numbers have a tendency to go beyond astronomically large (such as 10^120, 10^123 or the more or less arbitrary 10^500 vacua of the landscape though I doubt this number). The accounting for 8pi is still required and necessary (and difficult) where there are quantum corrections to GR in 4D and the only way I’ve been able to determine placement is by doing volumes of calculations. The dimensionless Planck units are the natural language and result of quantum gravity.

By: Weldon Vlasak

Weldon Vlasak — Wed, 23 Apr 2008 17:03:25 +0000

In order to understand Planck’s “normal” constants, it might be helpful to know what Planck actually said about them. Planck’s theory was based on the atom as an electronic oscillator (“Planck’s Columbia Lectures”). These “oscillators” (atoms) exchange energy as a function of temperature, and Planck’s state equation describes the frequency spectrum of the normal distribution of energy. The discrete changes in energy are equal to hf, where h is Planck’s constant, and f is the frequency. The constants h and k (Boltzmann’s constant) allows “…the means of establishing units of length, mass, time and temperature, which are independent of special bodies or temperatures, which necessarily retain their significance for all environments, terrestrial and human or otherwise, and which may therefore be describes as “natural units.”.

With the additional value of the velocity of propagation of light in a vacuum, c, and that of the constant of gravitation, f (BigG), the means of determining the four units of length, mass, time and temperature are given. The “Planck length”, as it is now referred to is 3.99 x 10-35 meter, the “Planck mass”
is 5.37 x 10^-8 kg, the Planck time” is 1.33 x 10^-43 sec, and the “Planck temperature” is 3.60 x 10^32 deg. Note that most all temperatures we would ever see would be less than Planck’s natural unit, whereas for length, some believe that Planck’s natural unit is the minimum length that can be attributed to any natural process.

In the second edition of his book, he does not state that these natural units are either maximums or minimums. That conclusion appears to have come later in time by others.

The present methods of measurement were made “… essentiallwith reference to the special needs of our terrestrial civilization. Thus the units of length and time were derived from the present dimensions and motion of our planet, and the units of mass and temperature from the density and the most important temperature points of water, as being the liquid which plays the most important part on the surface of the earth…”.

He makes an important qualifying statement: “These quantities retain their natural significance as long as the law of gravitation and that of the propagation of light in a vacuum and the two principles of thermodynamics remain valid; they therefore must be found always the same, when measured by the most widely differing intelligences according to the most widely differing methods. After over 100 years, the constants, h, f, and c have not changed. The gravitational constant may be in various amounts of error, depending on which reference you wish to cite.

Some authors prefer to divide h by 2-pi (h-bar), as a matter of convenience, but this constant appears in many equations in many circumstances in many applications, which is an indication of its great significance.

It is beneficial to research what the great scientists actually have stated about their theories. I wonder how many physicists realize that Planck’s theory is based on the energy states as determined by chemical measurements and laws, thermodynamics, radiation theory and electronic oscillators.

By: Sylvia

Sylvia — Thu, 03 Apr 2008 04:34:55 +0000

Integer multiples of 4π are ubiquitous in physics, simply because 4π appears in the formulae for the surface area and volume of the sphere.

“A minor problem is that it is probably missing a factor of 4π or maybe 8π…”

I warmly concur, simply because in general relativity, G nearly always appears as 8πG. Normalizing to 1 nicely streamlines the equations of general relativity, but introduces a factor of 8πG in the nondimensionalised version of Newton’s law. I can live with that.

Planck units should be modified so as to eliminate the stray instances of 4π in Maxwell’s equations, and in the curious gravitational analog of those equations:

http://en.wikipedia.org/wiki/Gravitoelectromagnetism

For my part, the purpose of Planck units is to purge from the algebra used to represent physical theories all constants that are, deep down, only conversion factors stenmming from arbitrary human choices of units of measurement. This suggest choosing units that normalize these conversion factors are 1 and hence eliminate them. The units that do this are precisely the Planck units.

A major problem with operationality of Planck units outside of pure theory, is that G has been experimentally determined to no better than 1 part in 10,000. This is pathetic, when compared to the accuracy of the electron & proton masses, the fine structure constant, the elementary charge, and so on. Moreover, G appears in the definition of nearly every Planck unit.

See

http://en.wikipedia.org/wiki/Natural_units

for several systems of natural units that do not normalize G, and so avoid many of problems raised in this interesting discussion. And here’s hoping that G will be known to within 1 part per million within the lifetimes of some of the readers of this blog.

By: Agress

Agress — Wed, 20 Feb 2008 21:40:11 +0000

Pioneer, thanks for links

By: Alejandro Rivero

Alejandro Rivero — Sun, 16 Sep 2007 22:50:23 +0000

About Planck charge, it remembers me that if you consider electromagnetism, then special relativity already gives you an angular momentum to be used instead of Planck constant: namely, the maximum angular momentum allowed for a closed orbit in the atom of hydrogen. Of course this is just $\alpha \hbar$, and then it suffers of the same renormalisation group criticism.
Amazingly these units are say (see Stoney Units in the wikipedia) to predate Planck… and relativity.

By: Numerology and Gravity « Secret Blogging Seminar

Numerology and Gravity « Secret Blogging Seminar — Fri, 14 Sep 2007 19:05:29 +0000

[...] 14, 2007 Posted by A.J. Tolland in QFT, mathematical physics. trackback Richard Borcherds wrote a post a little while back in which he remarked that we shouldn’t take the Planck units very [...]