Negative Energy

Tom Bearden writes:

For openers, here’s a late 1990s page by a professor for a standard physics course I quickly googled off the web, from http://www.shef.ac.uk/physics/teaching/phy303/phy303-8.html

When reading the various discussions of nuclear binding energy by different authors, it is easy to get confused because of an understood convention. Binding energy is always negative. When they talk about its magnitude, they mean its absolute value, so they just state the positive number.

You see, the nuclear physicists (like many parts of physics) have been very sloppy in definitions. E.g., here’s one definition advanced for nuclear binding energy:

Binding Energy: The binding energy of a nucleus is the minimum energy required to disassociate it into its component neutrons and protons. Neutron and proton binding energies are those required to remove a neutron or a proton, respectively, from a nucleus. Electron binding energy is that energy required to remove an electron from an atom or a molecule.

From a sheer logic standpoint, all three of those “definitions” are wrong. Restating them correctly:

The absolute values of the negative binding energy of a nucleus and the minimum positive energy required to dissociate the nucleus into its component neutrons and protons are equal.

The absolute values of the negative neutron and proton binding energies and the positive energies to remove a neutron or a proton, respectively, from a nucleus are equal.

The absolute values of the negative electron binding energy and the positive energy required to remove an electron from an atom or molecule are equal.

Hope that helps. Probably about half the physics students etc. are confused over the sloppiness.