What causes radioactive decay?

[JDude13]

So... I know that decay occurs when the nucleus of an atom has an unstable proton-neutron configuration.
My question is, at the instant that decay occurs, what triggers it? Is it quantum mechanical in nature? If so, why are half lives so consistent?

 

[jtbell]

at the instant that decay occurs, what triggers it?

We don't know.

Is it quantum mechanical in nature?

Yes.

If so, why are half lives so consistent?

For a particular decay process in a particular isotope, the probability of a decay occurring in the next time interval is a constant. For example, say a nucleus of a particular isotope has a 10% probability of decaying in the next minute via beta decay. If it survives for one minute, it now has a probability of 10% of surviving for the next minute. And so on. No matter how long it survives, the probability of it decaying in the next minute is still 10%. We can use this property to derive the exponential decay law and the half-life.

 

[Fewmet]

jtbell:

I think I heard somewhere (which makes me very uncomfortable with placing any value in it) that the uncertainty principle has a role in this. Is it that there is a finite possibility that the emitted particle be far enough from the nucleus that the net forces acting on it propel it away?

Thanks for considering what might be an uninformed question. I take some consolation in Eleanor Ducksworth defining learning as a process of making increasingly subtle mistakes.

 

[tom.stoer]

The quantum field theoretical explanation for the radioactive decay of nuclei are the strong and electro-weak forces which are responsible for alpha decay and beta-decay, respectively.

In all cases there is no reason why THIS nucleus decays NOW.

Look at qm tunneling through a potential barrier: you can only talk about the tunneling amplitude or probability, not about the time WHEN a certain particle will tunnel through the barrier.

 

[A. Neumaier]

So... I know that decay occurs when the nucleus of an atom has an unstable proton-neutron configuration.
My question is, at the instant that decay occurs, what triggers it? Is it quantum mechanical in nature? If so, why are half lives so consistent?

We call decay spontaneous because it is not triggered by anything we know of.

The reliability of measurements of the half-life comes from the law of large numbers.

 

[smith345]

I know what causes radioactive decay. And I REALLY understand quantum actions.

 

[monsteryash12]

Actually an unstable nucleus is constantly rearranging itself.since we cannot observe what goes on in the nucleus,decay is a random process.To answer your question more exactly,the cause of decay at that instant depends on the type of decay.in alpha decay the nucleons get arranged in such a way that the repulsion is high on particular protons.
its is of course quantum mechanical in nature.half lives are consistent because of the law of large numbers.Consider a single die.u roll it many times and the average will approach (1+2+3+4+5+6).the same case applies to the calculation and consistency of half lives.