THEME - I
CHARPAK et al.
JANSEN, FK - a
JANSEN, FK -b
IS THE UNIVERSE BASED ON HAZARDS ?
KRÖGER, Helmut Professor of Theoretical Physics
Professional literature at: http://xxx.uni-augsburg.de/find/hep-lat/
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TEXT received on 9.12. 2005
ON THE LENGHT SCALE OF ATOMIC
AND SUBATOMIC PHYSICS: YES
The subject is of great physical importance. It is not! a philosophical question, because the difference of a deterministic theory and a probabilistic theory can be verified experimentally.
(1) On the length scale of atomic and subatomic physics yes.
Quantum mechanics, the generally accepted theory of atomic physics, is expressed using deterministic laws, to describe random events.
Example: the Schrödinger equation. It is a deterministic equation describing a wave function, which can be seen in analogy to a probability density P(xsi) of a random variable xsi. P is a deterministic function, but it describes the distribution of a random variable xsi.
Likewise in physics the events are of random character.
Example: decay of Uranium atom, tunneling in Josephson junctions etc.
I want to go even a step further and ask:
“Why is quantum physics of probabilistic character? “
I offer two arguments/reasons:
First, if on the contrary, it were based on deterministic laws, nature could not be so simple. Possibly it would be so complicated putting its very existence into question.
Example: If the decay of a Uranium atom would be based on a deterministic law, a deterministic clock would be needed. Such clock would be terribly complicated compared to the simplicity of the Uranium atom.
Second, as is well known, the hydrogen atom would not be stable classically, because of energy loss due to synchrotron radiation. I go a step further and suggest that probability is the ground for the existence of stable energy levels in atoms, molecules, proteins, required for organic life.
Heisenberg's uncertainty principle says that the product of variances of the eigenvalues of position and momentum have a lower non-zero bound, related to a fundamental constant of nature. This is the fundamental law of quantum physics, showing its probabilistic character. This law is mathematically equivalent to the non-zero commutator relation between the position and momentum operator. Likewise, one can show that a Hamiltonian H=T+V gives stable states only if the operators of kinetic energy T and potential energy V have a non-zero commutator, equivalent to the existence of a lower bound on the product of variances of the eigenvalues of T and V, again related to the probabilistic character of quantum physics.
(2) At the scale of macroscopic physics, this is another story, which I suppose is not the topic of discussion here.