MadSci Network: Physics

Re: see descriptive comments box

Area: Physics
Posted By: Georg Hager, Grad student Theorie III
Date: Tue Mar 18 16:52:49 1997
Message ID: 858120828.Ph

Dear Andrew!

The first thing you have to realize is that the `spinning motion' of electrons in the atom is just a convenient model which is good in some respects (e.g. in calculating the energy levels in the atom), but inaccurate in others (you just have to feel uneasy with the Bohr postulate!). Quantum mechanics has better ways to describe the atom, but they are admittedly more complicated (basically, the electron does not `spin' --- it has certain probabilities to be here or there, and these probabilities can be calculated by solving a certain partial differential equation, the Schrödinger Equation).

But even if we assume that electrons do spin around the nucleus, how could this be responsible for inertia? Bare electrons which are not bound to any nucleus also have mass and thus inertia, and they do not have to `spin' at all. The real reason why massive bodies show inertia at all is still somehow mystical.

There is another misconception in your question: The assumption that the `movement' of electrons inside the atom has something to do with finite temperature. This is not the case. All you can say is that the higher the temperature is the more energy levels get `populated', i.e. electrons get `pushed' to higher energy levels (or even get kicked out of the atom, a process which is called ionization). In other words, at zero temperature, all electrons in an atom are in a configuration which ensures minimal energy for the whole atom, which means that they inhabit the lowest energy levels permitted by the laws of physics. But the mass of the particles which constitute the atom is still there, and so is inertia, even at absolute zero!


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