The Nature Of Binding Energy

The nucleus of an atom has a positive electric charge, being composed of a combination of positively-charged protons, and neutrons with no net electric charge. Logic tells us that, since like charges repel each other, the nucleus should not be able to hold together. However, as nuclei are crushed together in the centers of stars to form larger atoms from smaller ones, a certain "binding energy" takes over and holds the positively-charged protons together.

The force that holds nuclei together, against the supposed mutual repulsion that should take place, is also known as the strong nuclear force. But what exactly is this binding energy that takes over when nuclei are forced together?

In science books and illustrations an atomic nucleus is usually illustrated as a mass of spheres together, resembling a bunch of grapes. Protons might be blue, while neutrons are red.

But this simple illustration was developed before the quark model of nucleons was developed in the 1960s. A nucleon is simply a member of the atomic nucleus, a proton or neutron. Quarks are now a part of the so-called "Standard Model" of atomic and quantum physics.

In my view, water molecules are not neat spheres because they are composed of one relatively large oxygen atom and two smaller hydrogen atoms. This causes the water molecule to be polar, one side being more negatively-charged and the other more positive, so that the molecules can link to one another by hydrogen bonding.

So, why should either protons or neutrons be considered as forming neat little spheres when each are composed of three quarks. Up quarks have a +2/3 charge, and down quarks have a -1/3 charge. Two up quarks and one down quark give us the +1 charge on a proton, and two down quarks and one up quark balance out to the neutral charge on a neutron.

All matter, as we know it, is composed of up and down quarks and electrons. There are many other particles that are known to exist, but it is believed that if all the particles, other than these three suddenly disappeared, only particle physicists would notice.

In the posting "The Unification Of Forces", on this blog, I speculated that the three basic forces of nature; gravity, electromagnetism and, the strong nuclear force, are different manifestations of the same thing. It caught my attention that the weaker the force is, the greater the distance over which it can operate. This suggested to me that it was like a lever in which distance can be traded for strength. The real force behind all of these three is electromagnetism.

Suppose that the protons and neutrons in a nucleus, each of which is composed of three quarks, are not exactly the neat and simple spheres that they are usually illustrated as. What if there was some twisting and bending that was possible in the structure of the three quarks held together? Remember that there are both positive and negative charges within each proton and each neutron. Those in the proton balance out to +1, and those in the neutron balance out to zero.

When two nuclei are forced together by the tremendous pressure in the center of a star, the quarks within each proton and neutron twist and bend relative to each other so that positive and negative charges end up facing each other. This is what makes it possible for the positively-charged nucleus to hold together against the force of mutual like-charge repulsion. Notice that as atoms get larger, with more protons, a higher proportion of neutrons is required to hold the nucleus together.

This means that the force holding atomic nuclei together is actually electromagnetic. The "binding energy" is actually held in the twisting and bending of the quark structure in each proton and neutron, so that it acts like a spring. The true "binding energy" is in the bonds which hold quarks together, these must be stronger than the bonds which hold the protons and neutrons together in the nucleus.