What is the underlying mechanism of nuclear decay?

[csmcmillion]

I think I understand the basics of the SM and know that the W and Z bosons are the mediators of the Weak Force. I also understand from chem the basics about nuclear stability (ratio of protons to neutrons, valley of stability/nuclear binding energy, etc.). What I'd like to know is what the specific mechanism of decay is. In very simplistic terms, how does one of the neutrons in a C-14 atom "know" the nucleus would be in a lower energy state of it were to decay?

 

[Drakkith]

I'd personally say that it doesn't "know". It's just that when you add all the forces and mass and everything up together and do the math the neutron simply has a probability of decaying in C-14. I see it kind of like asking how a hockey puck "knows" that it has been hit by the stick. It doesn't know anything, it simply reacts to various forces. I guess this really depends on what you mean by "know".

Hopefully that makes sense and isn't blatantly incorrect.

 

[csmcmillion]

I'd personally say that it doesn't "know". It's just that when you add all the forces and mass and everything up together and do the math the neutron simply has a probability of decaying in C-14. I see it kind of like asking how a hockey puck "knows" that it has been hit by the stick. It doesn't know anything, it simply reacts to various forces. I guess this really depends on what you mean by "know".

Hopefully that makes sense and isn't blatantly incorrect.

Yeah - I know it doesn't really know (I have enough physics background for that) - that's why I used quotes. There must be some mechanism - some physical influence that increases the probability.

 

[Drakkith]

Yeah - I know it doesn't really know (I have enough physics background for that) - that's why I used quotes. There must be some mechanism - some physical influence that increases the probability.

Of course. It is a direct result of the different influences by forces and how they interact with various particles that make up the nucleus. Add in another proton and the probability vanishes and it's now the very stable nitrogen-15!

Edit: Sorry if that doesn't help much, I know what I'm saying in my head, but I have no idea how to get it across very well lol.

 

[csmcmillion]

Of course. It is a direct result of the different influences by forces and how they interact with various particles that make up the nucleus. Add in another proton and the probability vanishes and it's now the very stable nitrogen-15!

Right. But since the strong force is mediated (between nucleons) by mesons, there must be some interactions b/t mesons and the W/Z bosons that triggers the decay. This may be overly simplistic, but you get the idea of what I'm asking.

 

[Vanadium 50]

In very simplistic terms, how does one of the neutrons in a C-14 atom "know" the nucleus would be in a lower energy state of it were to decay?

How does a rock at the top of a hill "know" it would be in a lower energy state if it were to roll down?

 

[csmcmillion]

How does a rock at the top of a hill "know" it would be in a lower energy state if it were to roll down?

Come on guys, I know the rock doesn't know. Space pushes it into the lowest possible energy state. All I'm asking is what pushes a nucleon into decaying.

 

[Drakkith]

Come on guys, I know the rock doesn't know. Space pushes it into the lowest possible energy state. All I'm asking is what pushes a nucleon into decaying.

I don't know how to answer you. All I can say is that it is more favorable for the neutron to decay than for it to stay a neutron. It sounds like your asking something similar to "Why do heavier things decay into lighter things instead of being stable?". I'm not sure that we know or can know.

 

[Bill_K]

This question has come up multiple times in various guises, regarding any reaction: A + B → C + D. Why does it happen? Not because 'energy is decreasing'. Energy is not decreasing, it's exactly the same before and after. But it's partitioned differently.

The reaction is always taking place virtually. Usually there is no net effect because the inverse reaction C + D → A + B is also taking place virtually at the same rate. This is analogous to chemical equilibrium. But when the reaction is 'favorable', i.e. when the rest mass of the products C + D is less than that of the reactants A + B, the kinetic energy of the products is positive and they can leave the scene, making the reaction go predominantly one way.