A Geiger counter measures redioactive decay by registering the electrical pulsed produced in a gas tube when high-energy particles pass through it. The particles emanate from a redioactive source-say, radium. In accord with Heisengerg's Uncertainty Principle, does the act of measuring the decay rate of radium in any way alter the radium? yes or no ?

Question

A Geiger counter measures redioactive decay by registering the electrical pulsed produced in a gas tube when high-energy particles pass through it. The particles emanate from a redioactive source-say, radium. In accord with Heisengerg's Uncertainty Principle, does the act of measuring the decay rate of radium in any way alter the radium? yes or no ?

I think no. Is that right?

Answer 1

This is related to the classic thought experiment "Schroedinger's cat". Your answer seems intuitively correct, but in quantum mechanics, until a decay measurement is actually made, the radioactive source exists in a mixed quantum state, with nonzero probability that each radioactive atom has decayed or not. The measurement does alter the quantum mechanical state.

There is still a minority of theoretical physicists who are trying reformulate quantum mechanical postulates so that the Schroedinger cat paradox goes away.

See
http://en.wikipedia.org/wiki/Schrödinger's_cat
for an detailed and objective discussion of this question.

Answer 2

Yes, you are correct. According to Heisenberg's Uncertainty Principle, the act of measuring the decay rate of radium using a Geiger counter does not alter the radium itself. The Uncertainty Principle states that there is a fundamental limit to the precision with which certain pairs of physical properties, such as position and momentum, can be known simultaneously.

In the case of measuring the decay rate of radium, the Geiger counter is designed to detect the high-energy particles emitted by the radium as it undergoes radioactive decay. The particles interact with the gas tube in the Geiger counter, causing electrical pulses to be registered. This detection process does not directly affect the radium or alter its decay rate.

However, it is important to note that the act of measuring any physical system, including radioactive decay, introduces an element of interaction and disturbance to the system being measured. While the measurement itself does not directly alter the radium, it does introduce potential uncertainties in determining the exact properties of the radium or its decay rate.

So, to sum up, the act of measuring the decay rate of radium using a Geiger counter does not alter the radium itself, but it may introduce uncertainties in the measurement due to the inherent limitations imposed by the Uncertainty Principle.