Strong Electron Force

Factual Questions
1

Because every object with a mass has gravity, wouldn’t it stand to reason that the strong electron force is simply gravity between the parts of an atom? What is the deal?

2

According to the chart at the American Institute of Physics website, the attractive gravitational force in a nucleus has only 10^-36 the magnitude of the repulsive electromagnetic force. Something much stronger than gravity must be present to hold the nucleus together in spite of the electromagnetic repulsion.

Or are you referring to the force that attracts electrons to a nucleus?

3

I’m sure that JS Princeton will be along to explain in much better depth than I. But here’s my understanding of it:

None of the other forces (electromagnetic, strong and weak nuclear forces) act like gravity. Gravity attracts solely dependent on the masses of the objects involved, with an essentially infinite range, falling off with the square of distance. Electromagnetism attracts, repels, or deflects particles depening on their charge. The strong and weak nuclear forces have a lot of force, but only over a very limited range.

If gravity was what held atomic nuclei together, we would expect atoms to become more stable the larger they are. We find the opposite - very large atoms become more and more unstable, and above a certian size it is impossible for an atomic nuclei to hold together at all. From what I’ve heard this is due to the limited maximum range of the nuclear forces.

4

Not only do we know that gravity attracts things to one another, we know which things and how much.

  1. Gravity works on everything with mass, and always attracts them. The force is proportional to the mass, so everything in a given [strength of] gravitational field has the same acceleration. Gravity follows and inverse square law for distance, so it works fairly well at long ranges.

  2. The electromagnetic force works only on things that have an electrical charge. Some [pairs of] things it repels and others it attracts. The force is proportional to the charge, so things with different charge-to-mass ratios accelerate at different rates in the same [strength of] field. The electrostatic force itself follows an inverse square law for distance, but the magnetic aspect of the force (which is a relativistic residue, but we won’t go into that) follows and inverse cube law, so it is much shorter-range. Can you see that the electromagnetic force is different from gravity?

  3. Well, we know how strong the gravitational force between particles in a nucleus would be. The force that holds protons and neutrons together in a nucleus (and prevents the electromagnet force from pushing them apart) has to be about 1,000,000,000,000,000,000,000,000,000,000,000,000 times as strong as the gravity between those particles. Also, the strong force between atoms in a crystal lattice is too small to detect: so the strong force must fall off with distance much faster than inverse square. In fact, it isn’t even possible to detect its effect on the electrons of the very same atom (it would shift the emission lines of the elements from the positions we calculate using quantum electrodynamics if it had an appreciable effect), which means that it doesn’t effect electrons.

So: gravity affects electrons, the strong force doesn’t; gravity follows an inverse square law, the strong force doesn’t; given the masses and distances between of the hadrons in a nucleus, the strong force is much much stronger at close ranges than gravity.

Those are three reasons that it stands to reason that the strong force is not simply gravity.

Regards,
Agback