Can Point Particles Have Infinite Energy in Fields?

In summary, when finding the amount of energy stored in the electric field of a point particle, it is found to be infinite due to the r = 0 limit in the integral of the energy density. This is a recognized problem in classical electromagnetism and was not solved until the completion of Quantum Electrodynamics. One explanation for this infinite energy is that as the energy density increases for small r, more and more virtual e+/e- pairs are created, effectively shielding the charge at the center. However, this argument is not completely satisfactory as it assumes that even point particles have a finite size and that classical physics is not applicable at a certain scale. Additionally, the Standard Model includes point particles, which could be misleading in this context.
  • #1
urnchurl
8
0
When finding the amount of energy stored in the electric field of a point particle, one finds that it is infinite (due to the r = 0 limit in the integral of the energy density). Does this mean then that the field will never "run out" of energy?

How can the electric field of a point charge, or the gravitational field of a point mass contain an infinite amount of energy without resulting in a space-time singularity (if one considers a finite volume containing the point mass or charge)?

Thanks.
 
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  • #2
It would mean that the field contained an infinite amount of energy. This was a recognized problem in classical E&M and was not really solved until Quantum Electrodynamics was completed.

One way to think of the answer is that as the energy density increases for small r, you get more and more virtual e+/e- pairs, and they "shield" the charge at the center. At least, I think the argument goes something like that.
 
  • #3
The 1/r potential is valid as long as you are outside the charged body.
It is reasonable to assume that even an electron has a finite size.
Below a certain scale, classical physics is not applicable anyway.
 
  • #4
lalbatros said:
The 1/r potential is valid as long as you are outside the charged body.
It is reasonable to assume that even an electron has a finite size.
Below a certain scale, classical physics is not applicable anyway.

Doesn't the Standard Model comprehend point particles? That would seem to be particularly misleading.
 

Related to Can Point Particles Have Infinite Energy in Fields?

1. What does it mean when a field runs out of energy?

When a field runs out of energy, it means that there is no more usable energy left within the field. This can happen when the energy sources that sustain the field, such as a battery or power source, are depleted.

2. How can fields run out of energy?

Fields can run out of energy due to a variety of reasons. For example, in the case of electromagnetic fields, energy can be depleted by using up the energy source, such as a battery. In the case of gravitational fields, energy can be depleted when objects move away from each other and the gravitational potential energy decreases.

3. Can fields ever fully run out of energy?

No, according to the law of conservation of energy, energy cannot be created or destroyed, only transformed from one form to another. This means that while a field may run out of usable energy, the energy itself is not lost and can potentially be replenished.

4. What happens when a field runs out of energy?

When a field runs out of energy, it can no longer exert its force or influence on objects within its range. For example, an electromagnetic field that powers a light bulb will no longer be able to provide electricity to the bulb once its energy source is depleted. In the case of gravitational fields, objects within the field will no longer experience a gravitational force once the energy is depleted.

5. How can we replenish the energy in a field?

The energy in a field can be replenished by providing a new energy source. For example, in the case of electromagnetic fields, a new battery can be inserted to provide energy. In the case of gravitational fields, objects can be moved closer together to increase the potential energy of the field. Additionally, renewable energy sources such as solar or wind power can be used to replenish energy in various types of fields.

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