I Decoherence and Quantum tunnelling

[DesertFox]

TL;DR Summary

Why doesn't environmental decoherence completely prevent from happening the quantum tunneling of macroscopic objects?

A macroscopic object has the order of Avogadro’s number of particles. That’s over 10^23. So the probability of all of them tunneling, at the same time, is on the order of that original small probability, to the 10^23 power. And then on top of that, you have to factor in the chances of it happening in a place you can see it - as opposed to the enormous number of places in the universe you can’t. We can’t even imagine how small that is - we can’t even come close to imagining it. I’m perfectly comfortable dropping the nit-picking and calling something with that probability “impossible.”

If you think the point I’m trying to make is that this isn’t even worth talking about, you’re right. It’s not. It’s entertaining as a thought experiment, but these possibilities are utterly irrelevant to any aspect of real life.

On the other hand, whenever I saw discussion of such probabilities, the assumption has always been that decoherence is neglected (in fact, it's not even introduced yet as a concept at this point in texts).

Anyway, why does not environmental decoherence completely prevent from happening the quantum tunneling at macroscopic level?

 

[PeterDonis]

whenever I saw discussion of such probabilities, the assumption has always been that decoherence is neglected

Can you give specific references?

 

[PeterDonis]

why does not environmental decoherence completely prevent from happening the quantum tunneling at macroscopic level?

Why should it? The reasoning you give for why such tunnelling events are so drastically, super-astronomically improbable that we should never expect to observe one, looks correct to me, and doesn't mention decoherence at all. What more do you want?

 

[DesertFox]

Why should it?

It is actually the other way around: why should not?

Any substantial reasoning?

For, as a result of the loss of quantum coherence, quantum behaviour is apparently lost.

 

[PeterDonis]

It is actually the other way around

No, it isn't, because, as I pointed out, there is a perfectly valid reason (you give it yourself) why we don't observe such events that doesn't involve decoherence at all. So if you think decoherence should be involved, you need to explain why. You can't just assume it should be.

 

[DesertFox]

there is a perfectly valid reason (you give it yourself)

The reason I gave throws light upon the non-zero probability that quantum tunneling of macroscopic objects could happen. However, that is merely a logical (theoretical) possibility in the framework of quantum mechanics.

Another perfectly valid theoretical possibility is that there is a natural phenomenon (e.g. decoherence) which completely rules out the non-zero probability. As previously mentioned: as a result of the loss of quantum coherence, quantum behaviour is apparently lost.

It should be noted that shifting the burden of argument (between the two theoretical possibilities) is a hopelessly pointless and fruitless enterprise. So, please, if you have something on-topic and substantial to say (and not just quibbles evading the core of the question) - share it and that's it.

 

[Motore]

Another perfectly valid theoretical possibility is that there is a natural phenomenon (e.g. decoherence) which completely rules out the non-zero probability.

Is it? Can you show a reference supporting this?

 

[DesertFox]

Is it? Can you show a reference supporting this?

Basic logic: is it enough for a reference?

 

[weirdoguy]

Basic logic: is it enough for a reference?

A lot of people say that according to "basic logic" whole quantum physics is wrong, so no, it's not enough.

 

[DesertFox]

whole quantum physics is wrong

Nobody claims that.

Furthermore, scientific theories (quantum mechanics is no exception) do use logic. As a matter of fact, the non-zero probability that quantum tunneling of macroscopic objects could happen is merely a logical possibility within the framework of quantum mechanics; it is a theoretical prediction.

 

[Motore]

Basic logic: is it enough for a reference?

No, of course not.

Your question is the same as:

Anyway, why does not me sitting on the chair right now completely prevent from happening the quantum tunneling at macroscopic level?

Another perfectly valid theoretical possibility is that there is a natural phenomenon (e.g. me sitting on the chair right now) which completely rules out the non-zero probability.

(bold is my edited part of your quotes)

Which doesn't make sense.

Again, if you have references where quantum tunneling of macroscopic objects is prevented by decoherence, please provide them.

 

[DesertFox]

No, of course not.

To start with: the eluding from basic logic in your line of thought doesn't look very promising.

Again, if you have references where quantum tunneling of macroscopic objects is prevented by decoherence, please provide them.

Could you read post #4 and post #6? Or, may be you have to provide references where quantum tunneling of macroscopic objects cannot be prevented by decoherence?

As already stated, shifting the burden of argument (between two opposite logical possibilities) is useless activity.

So,

please, if you have something on-topic and substantial to say (and not just quibbles evading the core of the question) - share it and that's it.

And once again:

as a result of the loss of quantum coherence, quantum behaviour is apparently lost.

 

[Motore]

Or, may be you have to provide references where quantum tunneling of macroscopic objects cannot be prevented by decoherence?

The burden to prove that [insert random thing] could be the cause for the prevention of macroscopic objects to quantum tunnel lies with the one making such claims or connections. That is you, the OP, nobody else.

 

[DesertFox]

The burden to prove that [insert random thing] could be the cause for the prevention of macroscopic objects to quantum tunnel lies with the one making such claims or connections. That is you, the OP, nobody else.

That being the case, the burden to prove that the thing is "random" lies with the one making such conclusion.

Playing around with the burden of argument (between the two theoretical possibilities) is a hopelessly pointless and fruitless enterprise (see post #6).

Apart from, think about that: as a result of the loss of quantum coherence, quantum behaviour is apparently lost.

Something on-topic and substantial on your part?

 

[berkeman]

Thread closed for Moderation...

Update -- for a number of reasons, the OP is no longer with us. Thread will remain closed.