Question 15.S&C.7: 1. Is Heisenberg’s uncertainty principle applicable to the p...

1. No. Although we probably subject the temperature of water to a change by the act of probing it with a thermometer, especially one appreciably colder or hotter than the water, the uncertainties that relate to the precision of the thermometer
are quite within the domain of classical physics. The role of uncertainties at the subatomic level is inapplicable here.

2. Not at all, because the interaction involved is between the Geiger counter and the particles, not between the Geiger counter and the radium. It’s the behavior of the high-energy particles that is altered by measurement, not the behavior of the radium from which they emanate. See how this ties into the next question.

3. No. Here we must be careful in defining what we mean by observing. If our observation involves probing (giving or extracting energy), we indeed change to some degree that which we observe. For example, if we shine a light source onto the person’s back, our observation consists of probing, which, however slight, physically alters the configuration of atoms on his back. If he senses this, he may turn around. But simply staring intently at his back is observing in the passive sense. The light you receive (or block by blinking, for example) has already left his back. So whether you stare, squint, or close your eyes completely, you in no physical way alter the atomic configuration on his back. Shining a light or otherwise probing something is not the same thing as passively looking at something. A failure to make the simple distinction between probing and passive observation is at the root of much nonsense that is claimed by some to be supported by quantum physics. Better support for the above claim would be positive results from a simple and practical test, rather than on the assertion that it rides on the hard-earned reputation of quantum theory.