Talk:Compton wavelength

Compton length for one Planck mass

"The Compton length for one Planck mass is equal to the Planck length times 2 pi, and is also equal to the Schwarzschild radius times pi."

m = mC / lC

m is the mass

mC is the constant of proportionality

lC is the compton wavelength

Mass is inversely proportional to the Compton wavelength. The constant of proportionality, mC, is about 2.2102188e-42 kg.m

Compton wavelength of the electron

This page says the Compton wavelength of the electron is .39 times 10^-12 meters. Everyone else says it's about 2.42 times 10^-13 meters. So, I'm going to change this, to keep people from getting a wrong figure. But, as the above comment suggests, more careful thought needs to be put into this page. John Baez 22:11, 23 December 2005 (UTC)

If one computes the Compton wavelength via the formula quoted in this very article (or any textbook), one finds that h/mc is equal to about 2.4 x 10^(-12) m, not 2.4 x 10^(-13) m. Sigh. I fixed the value in this article. Michael Richmond, 12 January 2006

If one looks at the fact that Planck's constant has the dimensions of angular momentum and writes down an angular momentum expression of the form m x r x v = h (Planck's constant) and then evaluates this at v=c. One obtains an expression m x r = h/c . It can be seen that "r" the radius of the implied rotor, is identical to the Compton Wavelength associated with the given mass. Taking this a bit farther one may note that in this way of looking at the situation, Mass is a force at a distance from the center of a rotor and h/c can be considered as perhaps a constant of nature, some sort of universal torque. Additionally, mass and radius would be interchangeble values such that at a value of (h/c)^1/2 , they would have identical absolute values of approximately 4.7 x 10^-19 (cgs system) which could be considered as possibly being the radius of a fundamental particle of nature, which has been previously unsuspected.

It is also possible that "mass" then may well be a force, perhaps that component of the angular momentum of the given body which is so directed as to oppose motion in any direction. there seems alsi to be a possible implication that all fundamental particles may be rotating at the speed of light. Dean L. Sinclair October 16, 2007 —Preceding unsigned comment added by 24.220.20.182 (talk) 21:33, 16 October 2007 (UTC) This article needs a section on Compton scattering, the Compton scattering formula, and a diagram of the scattering event, since this is the origin of the Compton wavelength concept. — Preceding unsigned comment added by 75.164.84.5 (talk) 00:14, 7 December 2013 (UTC)

Rest mass vs. rest energy

"The Compton wavelength can be thought of as a fundamental limitation on measuring the position of a particle, taking quantum mechanics and special relativity into account. This depends on the mass m of the particle."

I disagree. It depends on the rest energy of the particle, not the mass.

$\lambda _{C}={hc \over E_{rest}}$

and

${\lambda _{C} \over 2\pi }={\hbar c \over E_{rest}}$

GoldenBoar 18:27, 4 January 2006 (UTC)

You are aware that rest mass and rest energy are equivalent, right? --Christopher Thomas 00:44, 8 January 2006 (UTC)

The concept of rest mass is wrong, a particle has mass not rest mass. — Preceding unsigned comment added by 98.219.64.187 (talk) 11:26, 12 January 2014 (UTC)

Looking at the situation with Planck's constant equated to its definition gives the equation m x r x v = h, and evaluating this at "c" to give the equation, m x r = h/c, one sees that this defines an oscillator set of constant torque, h/c. Since this is an oscillator there will be an instant at which m=r=(h/c)^0.5. A central, average unit for the rotationg objects upon which this equation operates. Testing the electron in this equation one finds that it fits into m x r = h/c with the rest mass equal to m, and the Compton wavelength equal to r, the radius. Since, in an oscillator the absolute values can be enterchanged to determine the othe3r limit of the oscillation, it can be shown that the "rest mass" is a minimal value associated with a maximum radius, which would be balanced at the other limit by a reciprocally lager mass and smaller radius, which can be determined by reversing the absolute values. This mathematically noted reversal--which implies an unexplored "counter existence" below (h/c)^0.5 in size--does not seem to have been examined. Dean L. Sinclair 5 March 2009 —Preceding unsigned comment added by Deanlsinclair (talk • contribs) 01:29, 6 March 2009 (UTC)

Hijacked by crackpots?

What is the image suppose to add to this article?

It seems like it just explores different relations between the various constants. It tries to assign some meaning to this and there is no reference. Also the image contains 6 different quantities, but the text below mentions only 5.

If this image should remain there should be at least one reference to confirm its claims. — Preceding unsigned comment added by 130.79.154.17 (talk) 11:16, 6 March 2013 (UTC)

Formula for photon scattering WRONG

The article contains an error in Relationship to Other Constants, when it claims the non-reduced Compton wavelength applies in the Thomson scattering cross section. Actually it is the reduced Compton wavelength, as shown in this article: http://en.wikipedia.org/wiki/Thomson_scattering Also, I have a physics textbook source: Nuclear and Particle Physics, Second Edition, B.R. Martin, pg 30. Fastman99 (talk) 23:15, 7 August 2013 (UTC)

Reduced versus non-reduced paragraph seems to be rather soft

I find the following paragraph rather questionable.

Relationship between the reduced and non-reduced Compton wavelength

The reduced Compton wavelength is a natural representation for mass on the quantum scale. Equations that pertain to mass in the form of mass, like Klein-Gordon and Schrödinger's, use the reduced Compton wavelength. The non-reduced Compton wavelength is a natural representation for mass that has been converted into energy. Equations that pertain to the conversion of mass into energy, or to the wavelengths of photons interacting with mass, use the non-reduced Compton wavelength.

This appears to be a rule of thumb for handling or remembering formulas, or a remark about conventions that are observed in formulas. As such, it is a student's remark, rather than a fundamental physical interpretation.

I would prefer to express it this way: the relationship is a factor of 2π.

If there is a more fundamental meaning to the "relationship", it should be noted, otherwise this paragraph should be omitted. 84.226.185.221 (talk) 09:08, 12 October 2015 (UTC)

Inconsistency in the section "Limitation on measurement"

There's a basic lack of flow, or incoherence, in the section entitled "Limitation on measurement".

The goal is to find a fundamental lower bound for the uncertainty Δx in the position of the particle. There are two slightly disparate explanations given.

In the beginning of the section, the position is measured by hitting the particle with a photon. The photon must have a small wavelength in order to measure the position accurately. But then the photon has a high energy, and risks producing a new particle of the same type, which renders the position measurement meaningless. So this gives a fundamental lower bound on Δx.

In the second half of the second, there is not longer any photon. Instead, we work directly with the Heisenberg uncertainty principle Δp Δx ≥ ħ/2 for the particle is invoked. It is combined with an inequality Δp ≤ mc, because we don't want so much energy uncertainty ΔE as to risk producing a new particle. So again we get a lower bound on Δx.

I realize that these two ways of discussing position-uncertainty are related (it is a very time-honored relationship). But they are not the same argument.

What is confusing is that the two discussions are not clearly distinguished. They kind of merge into one another, as if the second one were a continuation of the first one. One consequence of this is that the first discussion (with the measuring photon) is not brought to its quantitative conclusion. On the other hand, the second discussion (with Δp Δx) seems to have developed amnesia for the photon in the first discussion.

If I "YouRang" contributed any of this, feel free to delete it; it's mostly wrong-headed in a way that I sometimes do. — Preceding unsigned comment added by YouRang? (talk • contribs) 20:56, 1 September 2016 (UTC)

84.226.185.221 (talk) 10:08, 12 October 2015 (UTC)

Assessment comment

The comment(s) below were originally left at Talk:Compton wavelength/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.

The talk about uncertainty in the article is highly misleading. For one thing, it perpetuates a very simple-minded notion of where the uncertainty relation comes from, a notion that has confused many a student into thinking that quantum uncertainty is all about the practicalities of the measurement process. But more importantly, it concludes something that's basically incorrect--that it's impossible to localize a particle to a size scale smaller than its compton wavelength. One look at the formula for the wave function for the 1s orbital in a gold atom would dispel this myth. It also completely misses the basic importance of the Compton wavelength in the history of science. The Compton wavelength notion came about from the realization that light scattering from a free electron could be thought of as the interaction of two particles.

Last edited at 15:34, 7 May 2008 (UTC). Substituted at 12:08, 29 April 2016 (UTC)

A list of Compton wavelength for all known particles

Can we have a list of Compton wavelength for all known particles? Jackzhp (talk) 03:42, 24 November 2020 (UTC)

Compton and de Broglie wavelength

The following statement about the Compton wavelength in the introductory part of the current version bothered me.

"It is equivalent to the de Broglie wavelength with v = c."

The formula for the de Broglie wavelength is h/p. In the non-relativistic case this is h/(mv) and of course v=c can formally be set and the Compton wavelength is obtained. But that doesn't make any sense to me. Since the special theory of relativity applies for v->c, the formula in

https://en.m.wikipedia.org/wiki/Matter_wave#Special_relativity

has to be used. Then, de Broglie wavelength -> 0 for v -> c (and v=c for electrons is not physically possible here).

I'm not really an expert in the field. Could someone check? There is also a reference to de Brogli in the text.

Lojypeityr (talk) 19:56, 17 July 2022 (UTC)

Yes, the real speed at which de Broglie and Compton wavelengths are the same is at $v={\frac {c}{\sqrt {2}}}$. I also saw the error and fixed it before seeing this, same error was on the page for matter waves. Strange-attractor (talk) 18:25, 14 August 2022 (UTC)