Classic question regarding the nature of quantum tunneling

[DanteKennedy]

TL;DR

I'm curious if there's any way to suppress tunneling probability to absolute zero; is it even possible? Theoretically, is there a non zero chance (no matter how small) for large object (ex. cat, cars) to quantum tunnel in uncontrolled, everyday environment?

Read the TL;DR (^ w ^)

 

[PeroK]

If you've lost your cat, don't blame Quantum Mechanics.

 

[DaveC426913]

TL;DR: I'm curious if there's any way to suppress tunneling probability to absolute zero; is it even possible? Theoretically, is there a non zero chance (no matter how small) for large object (ex. cat, cars) to quantum tunnel in uncontrolled, everyday environment?

Read the TL;DR (^ w ^)

This is not endemic to QM.

Classically, there is a non-zero chance that all the air molecules in your room end up on the left side of the room, and you find yourself in hard vacuum (briefly).

No, you cannot suppress the tendency of air's heterogeny to absolute zero.

Likewise you could drop a box of jigsaw puzzle pieces on the floor and have them land in a perfecrtly completed puzzle.

But in each case, you might wait till the death of the universe for it to happen.



I lie. You wouldn't be waiting, you'd be observing over and over again, and getting partial results.

For each scenario, once in a^b seconds, two cat atoms would tunnel simultaneously, two air molecules would hug the left side of the room and two jigsaw pieces would stick together.

For every c times that happened, you might see three cat atoms, three air molecules and three puzzle pieces do something unexpected. etc, etc.


Sometime, in the next zillion^^yikes years, some cat will have an entire red blood cell collectively find itself elsewhere. And that will happen trillions of times over aeons, before the even more unlikely event where some cat has an entire toenail find itself elsewhere. On that time scale, toenail tunnelling events will effectively be "commonplace" - compared to whole legs tunnelling. etc.



Another way to think of it:

Statistically, before a million monkeys mashing at a million typewriters produced a single perfect copy of Shakespeare's works, they would first produce millions of false copies of the works with a single typo.

And for each of those but-for-one-letter copies, they would produce millions of false copies of the works that were perfect but for two typos. And for each of those, they would produce millions of three typo copies.

 

[AlexB23]

If you've lost your cat, don't blame Quantum Mechanics.

Wait, that is where the missing socks go. They tunnel into the floor.

 

[pines-demon]

Maybe with the right potential geometry and the right energy you can make the transmission be 0 for specific point in space.

 

[PeroK]

Just to add that electron tunnelling is a specific phenomenon that is useful in microelectronics. But, everything about the macroscopic world is essentially determined by the probabilities of large numbers. Everything we learn about macroscopic processes is not strictly speaking fully determined by some law of physics or chemistry or biology, but is also determined by a probability that is as close to certain as makes no difference.

That's everything from basic chemistry (chemical reactions are probabilistic), cell biology, organ function, life, growth, everything.

There is no more reason to expect a cat to tunnel through a wall than for any other statistically impossible event to occur.

The law of large numbers is what it is. There is no need to override it with some absolute certainty. It does its job by making the macroscopic world look deterministic and predictable (in certain respects). In particular that a cat is a functioning animal subject to the laws of chemistry, biology and classical physics.

 

[DanteKennedy]

Just to add that electron tunnelling is a specific phenomenon that is useful in microelectronics. But, everything about the macroscopic world is essentially determined by the probabilities of large numbers. Everything we learn about macroscopic processes is not strictly speaking fully determined by some law of physics or chemistry or biology, but is also determined by a probability that is as close to certain as makes no difference.

That's everything from basic chemistry (chemical reactions are probabilistic), cell biology, organ function, life, growth, everything.

There is no more reason to expect a cat to tunnel through a wall than for any other statistically impossible event to occur.

The law of large numbers is what it is. There is no need to override it with some absolute certainty. It does its job by making the macroscopic world look deterministic and predictable (in certain respects). In particular that a cat is a functioning animal subject to the laws of chemistry, biology and classical physics.

Interesting, but do you personally think that there's a way to suppress quantum tunneling probability to be absolute zero? I've heard about quantum zeno effect, but i didn't quite grasp it, because there's also anti zeno effect; It's a recent knowledge for me

 

[DanteKennedy]

Another way to think of it:

Statistically, before a million monkeys mashing at a million typewriters produced a single perfect copy of Shakespeare's typo.

And for each of those but-for-one-letter copies, they would produce millions of false copies of the works that were perfect but for two typos. And for each of those, they would produce millions of three typo copies.

Are statistically unlikely quantum or thermodynamic events caused by true randomness (each "step" has independent probability from previous condition) or "pseudo" randomness?

 

[FactChecker]

You are asking about something that is so unlikely that any theories will/have remained unverified for a very long time (billions of years). So the best you can expect now are speculations and assumptions.

 

[DaveC426913]

Interesting, but do you personally think that there's a way to suppress quantum tunneling probability to be absolute zero? I've heard about quantum zeno effect, but i didn't quite grasp it, because there's also anti zeno effect; It's a recent knowledge for me

Any chance this is research for a sci-fi story? We have a forum for that.

 

[PeroK]

Interesting, but do you personally think that there's a way to suppress quantum tunneling probability to be absolute zero? I've heard about quantum zeno effect, but i didn't quite grasp it, because there's also anti zeno effect; It's a recent knowledge for me

Theories can only be tested so far. It's an open question whether a cat could tunnel through a wall by sheer randomness. The probability is so low, that we can't hope to test it. The question is generally irrelevant to understanding QM.

For example, you could become undefeated world chess champion by playing moves at random. There is a much greater likelihood of that than of the phenomena you want to talk about. And, if you meet Magnus Carlsen and explain that you could beat him 100 games in a row , just by playing moves at random and relying on finding the best move every time, then I imagine he would be unperturbed. That unlikely eventuality is irrelevant to chess theory.

The quantum zeno effect applies to systems that admit to testing in ways a cat does not.

In general, it doesn't help to try to think of an object like a cat in pure QM terms. Basic QM principles can't be seen by studying a cat. The number of paws a cat has is independent of whether you count them. Too much time is wasted trying to find QM analogies in macroscopic objects.

 

[PeterDonis]

Are statistically unlikely quantum or thermodynamic events caused by true randomness (each "step" has independent probability from previous condition) or "pseudo" randomness?

We don't know. Different interpretations of QM say different things about this.

 

[FactChecker]

Too much time is wasted trying to find QM analogies in macroscopic objects.

Very true. But it should be added that some work is going on in quantum computing/error correction, and quantum communication with larger entangled objects. These are still infinitesimal compared to a cat.