# Does electron have real physical mass?

1. Aug 22, 2004

### kichigai

I read that the electron may not have a real physical mass at its center. Is that possible? Does the electron have real physical mass at its center?

2. Aug 22, 2004

### HallsofIvy

Staff Emeritus
An electron certainly has mass. I'm not sure that's what you mean by "real physical mass". When you are at the size of an electron, the distinction between wave and particle (which is what I suspect you mean) is not clear.

3. Aug 22, 2004

### kichigai

Mass is normally considered to be a form of potential energy or binding energy if I understand correctly. But "physical mass" or maybe it's called "mechanical mass" means something like a thing that has no electric or magnetic properties. Just a lump of something. I read about this in a book called: The Enigmatic Electron.

4. Aug 23, 2004

### zefram_c

Mass is a physical property expressed through either inertia (resistance to movement) or gravity. Inertial mass is definitely a property of an electron. While electrons are affected by gravitational fields much like everything else, its own field is far too weak to measure directly.

Who authored that book, and what are the author's credentials?

5. Aug 23, 2004

$$M_e = 9.11*10^{-27} kg$$

6. Aug 23, 2004

### Hilbert Space

That's not correct. The mass of the electron is 9.1 E -31 kg, not -27.

7. Aug 23, 2004

### marlon

In QFT, electrons have a mass after interacting with the Higgs-field. Mass can thus be seen as a sort of coupling constant for the "Higgs-interaction"

Once this mass is acquired, we have to take into account renormalization. The physical mass that we measure is not really the QFT-mass after Higgs-interaction. The mass acquired after this interaction is called the naked mass, but the particle is surrounded by an infinite amount of virtual particles that lead to an infinite mass-value. So the naked mass value is also infinite but in a socalled negative way so that the two contributions (naked mass + virtual particles) give a finite positive mass value. This is the real physical mass.

These virtual clouds that surround a "naked" particle are things that come from the QED of Feynmann in order to describe the interactions between fermions for example.

regards
marlon

8. Aug 23, 2004

my mistake, soo many constants and masses on my mind.

9. Aug 23, 2004

### what_are_electrons

Malcolm H. MacGregor, UC Berkeley / Lawrence Livermore National Labs now retired.

10. Aug 23, 2004

### what_are_electrons

With respect to the gravity of the earth, this is the mass in its weight form. But I believe that particle physicists tend to use energy values such as: 0.511 MeV for the electron which is why it is easy to understand that mass is said to be potential energy or binding energy. (My use of the terms: potential energy and binding energy, are out of context.)

I find it easier to understand the energy based nature of mass when I think of some object in outer space where there are no obvious gravitational effects and yet the object still has the same form as it did on the surface of the earth. Then I think of the energy that exists within and between the protons, electrons and neutrons within that form.

11. Aug 23, 2004

### what_are_electrons

In this case, are you describing energy based mass or mechanical mass (aka real physical mass)?

We speak of mass as being an energy value (often called potential or binding energy) and I asked about a "mechanical mass" which can also be called a "real physical mass" and so it seems we are describing the same object, but I want to be sure.

I think I understand that "real physical mass" is the interaction of "naked mass" and "virtual particles" where the virtual particles are within some distance of the naked mass, but I'm not quite understanding the other terms.
I need a bit more help with the terms:
a) infinite mass
b) naked mass
c) positive mass

12. Aug 24, 2004

### marlon

a) i mean that the mass value has to be infinite because of the contributions of the virtual particles. You can think of these particles as having the same role of the index k (from 0 to infinity) when using the sommation sigma-operator. What are you summing up ? Well, All the different interactions in perturbationtheory.

b) this is the mass of the particle without taking into account the virtual particles.

c) euuh, I just mean a finite positive value...

regards
marlon