|San José State University|
& Tornado Alley
The Notion of Nuclear Rotations|
and Estimates of Rates
What a profound notion is nuclear rotation. It is in contradiction to the Copenhagen Interpretation of quantum physics which holds that subatomic particles do not generally have a physical reality. Instead, according to that interpretation, they exist only as probability density distributions unless they are subjected to an observation that collapses their probability distribution to a point. Particles existing only as probability distributions cannot display structures and their rotation.
Nuclear rotation is also in contradiction to several of the standard models of nuclear structure such as the Independent Particle Model.
Nuclear rotation implies some sort of structure composed of nucleons. The structure may not be for the entire nucleus but it could be for a nuclear shell. The question is then what sort of structure can exist among the nucleons in a shell. One possibility and perhaps the only possibility is spin pairing. For more on this see What holds a nucleus together?.
One of the first studies of nuclear rotation was undertaken by Aage (pronounced oh-weh) Bohr and Ben Mottleson and published in Volume 2 of their Nuclear Structure. Bohr and Mottleson found that nuclear rotations obey the I(I+1) rule; i.e., have energy levels EI such that
where I is an integer, J is the moment of inertia of the rotating nuclear shell and
Planck's constant divided by 2π. Bohr and Mottleson cautiously stated that nuclei appear to rotate
and satisfy the I(I+1) rule because AAge Bohr's father, Niels Bohr, was a major founder of the
Copenhagen Interpretation that maintains that such rotations cannot exist.
Note what the Bohr-Mottleson I(I+1) rule implies about the quantification of angular momentum. If ω is the rate of rotation in radians per second then
Thus angular momentum L is given by
where ω is the rotation rate in radians per second.
This is in contrast to the Old Quantum Physics of Niels Bohr in
which L would be
and thus the smaller the moment of inertia the faster a structure rotates.
However the angular momentum is always
Most structures have a number of different modes of rotation, each with its own moment
of inertia. Regardless of the differences in moments of inertia each mode of rotation
will have the same angular momentum.
Thus there is an equipartition of angular momenta among the various modes of rotation.
A deuteron consists of a proton and a neutron. The neutron has slightly more mass than the proton. For purposes of this order of magnitude estimate the differences between the neutron and the proton will be ignored. It is thus the computation for a pseudo-deuteron.
The diameter of the deuteron is approximately 4.2 fermi. The charge radius of a proton is 0.877 fermi. Deducting two proton radii from the diameter of the deuteron gives a separation distance of the particle centers of 2.446 fermi and thus an orbit radius of 1.223 fermi.
The mass of a proton is 1.673×10-27 kg. Thus the moment of inertia of a deuteron for rotation about an axis perpendicular to its longitudinal axis is
The minimum rate of rotation is thus
The number of complete rotations per second is 4.74×1021. This is about 5 billion trillion times per second, an almost unbelievably fast rate of rotation.
This figure is so large that I looked for confirmation in the literature on nuclear physics. One possible source for confirmation is the book by Zdzislaw Szymanski of the University of Warsaw entitled Fast Nuclear Rotation. Incredibly in the 220 pages of text there is not one figure given for a rate of rotation in rotations per second. Rates of rotation are only given in terms of quantum numbers.
In the Guide to the Nuclear Science Wall Chart there is this statement
[…] scientists can create nuclei which have very high angular momentum. Nuclei respond to this rotation, which can be as fast as a hundred billion billion revolutions per second[…]
This is an order of magnitude smaller than the computed rotation rate for a deuteron but it is an equally almost unbelievably fast rate.
A similar computation for an alpha particle gives a rate of rotation of 4.194×1021 per second, the same order of magnitude as for a deuteron.
The question arises as to what such rates of rotation imply about the velocity of the subparticles of a structure in relation to the speed of light. That velocity is v=ωr, where r is the orbit radius for the particle. For the deuteron that is
The factor 1/(1−(v/c)²)½ is then 1.007455, not a lot of correction needed.
Thus the computed rates of rotation are compatible with the Special Theory of Relativity.
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