23 minutes ago, swansont said:

L has a different value for each unstable nucleus. There are models that give answers, though I couldn't tell you how precise they are. Alpha decay, for example, can be modeled as an alpha particle tunneling out of a potential well.  And there are trends one can apply — for a given type of decay, a larger release of energy typically correlates to a shorter half-life.

Thanks. Does the concept of half lives also apply to particle decay in general or just to radioactive decay of the nucleus?

Does the wave property of particles  have any bearing in the phenomenon of half lives?

 

Can/could  particle decay be used  to measure time?

https://en.wikipedia.org/wiki/Particle_decay  (just to specify what I am hopefully referring to)

 

1 hour ago, studiot said:

As ever I come in to say that Nature is never that simple.

 

Suppose I my watch is displaying 1200 noon and I check my watch against the national time signal every 12 hours for a week and each reading show 1200.

 

Should I conclude that

 

1) The watch is keeping correct time and that the hands are moving?

or

2) That the watch has stopped and the hands are not moving?

You should conclude that the concepts of 'change' and 'motion' on one side, are not the same as the methods to investigate them on the other.

Edited April 9, 20187 yr by Eise

1 hour ago, studiot said:

As ever I come in to say that Nature is never that simple.

 

Suppose I my watch is displaying 1200 noon and I check my watch against the national time signal every 12 hours for a week and each reading show 1200.

 

Should I conclude that

 

1) The watch is keeping correct time and that the hands are moving?

or

2) That the watch has stopped and the hands are not moving?

2 since the former alignment   degrades with time.  (if your clock shows exactly 1200)

1 hour ago, geordief said:

Thanks. Does the concept of half lives also apply to particle decay in general or just to radioactive decay of the nucleus?

Excited state lifetimes follow the same principle.

1 hour ago, geordief said:

Does the wave property of particles  have any bearing in the phenomenon of half lives?

Not in any obvious way, as far as I aware. 

1 hour ago, geordief said:

Can/could  particle decay be used  to measure time?

https://en.wikipedia.org/wiki/Particle_decay  (just to specify what I am hopefully referring to)

Yes. There are various ways of using decay to measure elapsed time. C-14 dating is used for terrestrial things in the recent past, that were once alive. K-Ar dating is one method used for dating certain types of rocks.

2 hours ago, geordief said:

Have you an example of a physical change which  does not involve a motion?

Changes in quantum states need not involve motion.

43 minutes ago, swansont said:

 

Changes in quantum states need not involve motion.

Can you give a specific example?

(If electrons jump to a different level  in an atom can that  be considered as "discontinuous motion"?)

42 minutes ago, geordief said:

Can you give a specific example?

A spin-flip of an electron. It goes from e.g. the |m=-1/2> state to the |m=+1/2> state 

Quote

(If electrons jump to a different level  in an atom can that  be considered as "discontinuous motion"?)

An electron jump does not involve motion, as such. There is no trajectory for the electron, so referring to it as motion doesn't really make sense. The probability distribution will change.