If we wait infinitely long, will macroscopic objects undergo quantum tunneling?

[Kinker]

TL;DR Summary

If time in the universe is infinite, or if there are infinite universes with the same physical laws as our universe, is it inevitable that macroscopic objects visible to the naked eye will inevitably experience quantum tunneling at some point?

If time in the universe is infinite, or if there are infinite universes with the same physical laws as our universe, is it inevitable that macroscopic objects visible to the naked eye will inevitably experience quantum tunneling at some point?
Or is it an absolutely impossible event because the probability is too low or due to other factors? It can happen at the microscopic level, but is it absolutely impossible at the macroscopic level due to various factors such as quantum decoherence and emergent properties?

 

[PeroK]

TL;DR Summary: If time in the universe is infinite, or if there are infinite universes with the same physical laws as our universe, is it inevitable that macroscopic objects visible to the naked eye will inevitably experience quantum tunneling at some point?

If time in the universe is infinite, or if there are infinite universes with the same physical laws as our universe, is it inevitable that macroscopic objects visible to the naked eye will inevitably experience quantum tunneling at some point?
Or is it an absolutely impossible event because the probability is too low or due to other factors? It can happen at the microscopic level, but is it absolutely impossible at the macroscopic level due to various factors such as quantum decoherence and emergent properties?

Why is this question of any importance?

 

[Nugatory]

Or is it an absolutely impossible event because the probability is too low or due to other factors? It can happen at the microscopic level, but is it absolutely impossible at the macroscopic level due to various factors such as quantum decoherence and emergent properties?

We can calculate the probability of such a thing happening, and we will come up with a small non-zero number. You may, if you choose, attach the words "not absolutely impossible" to this statement - but this tells us more about how you are defining "absolutely impossible" than about how macroscopic objects behave.

Similar questions can be asked even in classical physics. The air pressure underneath my kitchen table is largely balanced by the air pressure above (and both are much greater than the weight of the table) so it stays put. However, the air molecules on both sides are in random thermal motion and there is a non-zero probability (maybe something like $2^{-(10^{25})}$) that they will all just happen to be moving upwards at the same time - the table would blast through the ceiling and roof like an artillery shell. Is there any value in saying that that is not "absolutely" impossible?

As an aside, the quantum mechanical probability of the table tunnelling through the floor is unimaginably smaller than that, maybe $(10^{100})^{-(10^{25})}$.

 

[Vanadium 50]

If I put a chair in a box, the time it takes to be expected to tunnel out exceeds the time it takes for the chair to evaporate.

 

[Kinker]

Why is this question of any importance?

I asked a question because I didn't feel it was accepted intuitively.

 

[DaveC426913]

There's a lot of qualifiers that have to be met before this can be said to be true - one example - as Vanadium points out, is that real objects don't live infinitely long.

Especially when you consider that, long before an entire chair could undergo quantum tunnelling, it is much more likely that small parts of it will undergo tunnelling, leaving a semi-chair, so what is left? (i.e. How many times will an infinite supply of chairs each partially tunnel before you get just one that happens to tunnel in its entirety?)

If you systematically address and eliminate each of these qualifiers, one by one, you may eventually reach the answer that - in principle, given sufficient time and these qualifiers - some macroscopic object could undergo tunnelling, and end up elsewhere in its same configuration.

I think.

It's a similar thought experiment - though not the same - as the idea of random interstellar atoms in the void happening to come together into the shape of a chair (which is classical physics).

If you're interested in extremely unlikely things happening, I think reading up on Boltzmann Brains might yield some fruit.

 

[hutchphd]

TL;DR Summary: If time in the universe is infinite, or if there are infinite universes with the same physical laws as our universe, is it inevitable that macroscopic objects visible to the naked eye will inevitably experience quantum tunneling at some point?

It can happen at the microscopic level, but is it absolutely impossible at the macroscopic level due to various factors such as quantum decoherence and emergent properties

This statement is nonesense (as pointed out previously). Is absolutely impossible more impossible than impossible?? Where is this line between micro and macro? How many angels......

 

[GarberMoisha]

No. Classical objects do not undergo quantum tunneling as they are not known to be in a state of superpositions. It is simply impossible to isolate them from the environment and prevent decoherence and measurement. If you could cool them down and isolate perfectly, they might be able to in a trillion years or more. Theoretically at least. This is a tricky question that is lying in a grey zone of maybe's and shouldbe's.
Choose a smaller object like a virus and it will make sense even with today's capabilities to make a prediction.

 

[romsofia]

It would do you good to see just how little tunneling occurs in macroscopic objects like the Sun. See if you can set up the problem of how much of the core is tunneling at a given instance, and you will quickly see how absurd it would be for a macroscopic object to ever tunnel.

The sun NEEDS quantum tunneling to work, and even then it's ABSURDLY rare for it to happen!

 

[PeterDonis]

The sun NEEDS quantum tunneling to work

How so?

 

[DaveC426913]

they might be able to in a trillion years or more. Theoretically at least

 

[vanhees71]

In fusion the Coulomb barrier is overcome via the tunnel effect.

 

[hutchphd]

simply impossible

So we have impossible, absolutely impossible, and simply impossible? I know I am quibbling but unlikely and impossible mean different things. All things are quantum mechanical (IMHO), often that seems a complication but sometimes it is not salient.

 

[romsofia]

How so?

Sun isn’t massive enough to have nuclear fusion without quantum tunneling. So, our sun would have a different composition and would be dimmer if tunneling couldn’t occur. It would just be some other astrophysical object.

Thus, one must conclude that our sun needs the phenomenon of quantum tunneling in order to be “The Sun” and not “random white dwarf 548”.

 

[PeterDonis]

Sun isn’t massive enough to have nuclear fusion without quantum tunneling.

Again, how so? A reference for the claims you are making would help.

 

[GarberMoisha]

So we have impossible, absolutely impossible, and simply impossible? I know I am quibbling but unlikely and impossible mean different things.

It's hard to say from today's perspective what will be possible in 200 years - i can't think of good reason why a perfectly isolated IKEA chair will not produce an excellent interference pattern.

All things are quantum mechanical (IMHO), often that seems a complication but sometimes it is not salient.

Yes, It's weird to me, I already noticed it raises many an eyebrow here talking to quantum physicists about the existence of.... classical objects. They will quantize everything and then go on to use their classical apparati to probe.... the quantum. Because everything is quantum except the very tools... which are also supposed to be quantum but thank God they are not. So they can be used accordingly.

 

[PeterDonis]

I already noticed it raises many an eyebrow here talking to quantum physicists about the existence of.... classical objects.

No, it doesn't. Quantum physicists have no problem at all with classical objects--as limiting cases under particular conditions.

They will quantize everything and then go on to use their classical apparati to probe.... the quantum. Because everything is quantum except the very tools... which are also supposed to be quantum but thank God they are not.

No, we do not know that measuring tools are not quantum. The usual position taken by quantum physicists is that measuring tools are approximated well enough by the classical limit of QM that we can treat them as classical objects for practical purposes. But that is not the same as them being classical objects if "classical" means "not quantum" in some fundamental sense.

 

[PeroK]

It occurs to me that the wall is irrelevant. If you put a chair in an otherwise empty room, then remove the ceiling and knock down all four walls, it still doesn't go anywhere of its own accord. It's not the walls that keep the chair where it is.

If you take the floor away, that's a different matter.

 

[Quantum Waver]

Why is this question of any importance?

It's a potential issue for probability in MWI and infinite universes, since it suggests there will be observers who observe incredibly improbable events, thus messing up their understanding of probability. Sean Carrol has mentioned this as a criticism of MWI. His retort is so much the worse for those observers, but we don't have to worry about them, since it's incredibly unlikely we would end up being them.

I realize this isn't the Interpretation forum, but I replied since it was asked here.

 

[PeterDonis]

I realize this isn't the Interpretation forum, but I replied since it was asked here.

The question wasn't asked of you, it was asked of the OP of this thread, which is not you.

 

[Quantum Waver]

We can calculate the probability of such a thing happening, and we will come up with a small non-zero number. You may, if you choose, attach the words "not absolutely impossible" to this statement - but this tells us more about how you are defining "absolutely impossible" than about how macroscopic objects behave.

Similar questions can be asked even in classical physics. The air pressure underneath my kitchen table is largely balanced by the air pressure above (and both are much greater than the weight of the table) so it stays put. However, the air molecules on both sides are in random thermal motion and there is a non-zero probability (maybe something like $2^{-(10^{25})}$) that they will all just happen to be moving upwards at the same time - the table would blast through the ceiling and roof like an artillery shell. Is there any value in saying that that is not "absolutely" impossible?

Yes, because there is nothing preventing it from happening in the next ten minutes. It's just incredibly unlikely. And in a vast enough universe, it would happen somewhere. That's different from something like perpetual motion. And it's potentially relevant for the cosmos over the long term, since eventually, extremely low probability quantum fluctuations would happen. Thus the Boltzmann brain concern.

 

[Quantum Waver]

The question wasn't asked of you, it was asked of the OP of this thread, which is not you.

Just explaining why I commented in this sub.

 

[romsofia]

Again, how so? A reference for the claims you are making would help.

I guess theoretically it can occur (https://sites.uni.edu/morgans/astro/course/Notes/section2/fusion.html) However, for this level of this thread, I would think this article explains it pretty well: https://bigthink.com/starts-with-a-bang/quantum-reason-sun-shines/

And then for more thought on it (if tunneling didn’t exist): https://astronomy.stackexchange.com...ar-reactions-could-not-proceed-via-quantum-tu

 

[Nugatory]

And in a vast enough universe, it would happen somewhere.

We have to be a bit careful with this claim. The probability of the almost-impossible thing happening is a very small non-zero number, which implies that the probability of it not happening is one minus that very small number - and that number is less than unity for any finite time interval. Thus, there is no certainty that it will happen no matter how long we wait.

 

[Quantum Waver]

We have to be a bit careful with this claim. The probability of the almost-impossible thing happening is a very small non-zero number, which implies that the probability of it not happening is one minus that very small number - and that number is less than unity for any finite time interval. Thus, there is no certainty that it will happen no matter how long we wait.

In MWI it would have to happen in some branch, as the universal wave equation is deterministic, assuming the calculation of non-zero probability is correct. In an infinite universe, everything physically possible also happens. I was assuming a vast enough universe to contain all those low probability events would also do the trick. One where the topology appears flat because it's so big.

 

[PeroK]

And it's potentially relevant for the cosmos over the long term, since eventually, extremely low probability quantum fluctuations would happen. Thus the Boltzmann brain concern.

These are not concerns. The Sun will inevitably die; not with some infinitesimal probablity, but with certainty. It will not burn as a life-supporting star for ever. Even that's hardly a concern, given that climate change (whether human-induced or otherwise), nuclear war, asteroid impact, or deadly global virus are all very likely (if not inevitable) at some stage in human history.

You can't have an international conference on whether the Earth is actually just an instantaneous existence of a Bolzmann brain. It's an irrelevant question, of no consequence. There's nothing you can do with a question like that.

You also seem to labour under the illusion that if an unlikely event happens, then that sets the tone for the future. Even if a chair tunnelled out into the back yard, we'd just assume someone took it out there for some unknown reason and we'd bring it back into the house and carry on with our lives. It's not like we'd have to rewrite the laws of physics. Even if someone saw it, no one would believe them.

Also, it's not what science is about. The medical profession doesn't ponder the question of what happens if - by pure coincidence - every adult on Earth breaks a leg on the same day. That has a likelihood that is at least calculable. Why are you not concerned about that? What would happen to human society if everyone had a near fatal accident on the same day? Without any help from QM, that's inevitably going to happen some day, to some unlucky intelligent species in the Cosmos. But, it's still a total irrelevance. Unlike the almost inevitable asteroid strike.

 

[DaveC426913]

It's a potential issue for probability in MWI and infinite universes, since it suggests there will be observers who observe incredibly improbable events, thus messing up their understanding of probability. Sean Carrol has mentioned this as a criticism of MWI.

This argument makes no sense. It's somewhat analogous to saying because it is incredibly unlikely for a given player to win the lottery, a given player who does win would have his understanding of probability messed up.

 

[Quantum Waver]

This argument makes no sense. It's somewhat analogous to saying because it is incredibly unlikely for a given player to win the lottery, a given player who does win would have his understanding of probability messed up.

It's more like there would be parts of the cosmos where the incredibly improbably happens on a regular basis. So coins turn up heads a thousand times in a row, dice roll sixes a million times, people walk through walls some of the time, etc. Assuming life can survive in such conditions, the observers would not find such events ot be low probability. DeWitt mentions this in his paper on MWI.

 

[PeroK]

It's more like there would be parts of the cosmos where the incredibly improbably happens on a regular basis. So coins turn up heads a thousand times in a row, dice roll sixes a million times, people walk through walls some of the time, etc. Assuming life can survive in such conditions, the observers would not find such events ot be low probability. DeWitt mentions this in his paper on MWI.

This is not what physics is about. There's no evidence for any of this stuff. It's chasing a hypothetical fantasy.

 

[Quantum Waver]

This is not what physics is about. There's no evidence for any of this stuff. It's chasing a hypothetical fantasy.

Then take that up with the physicists who worry about that stuff in cosmology and foundations. Physics is about what physicists study.

 

[PeterDonis]

I guess theoretically it can occur (https://sites.uni.edu/morgans/astro/course/Notes/section2/fusion.html)

This site just says the minimum stellar mass for hydrogen fusion is 0.08 solar masses. It says nothing at all about quantum tunnelling or lack thereof in calculating that threshold.

However, for this level of this thread, I would think this article explains it pretty well: https://bigthink.com/starts-with-a-bang/quantum-reason-sun-shines/

This is a pop science article and I cannot find any references in it to actual textbooks or peer-reviewed papers. The article describes calculations, but doesn't actually do them or point to references where they are done.

And then for more thought on it (if tunneling didn’t exist): https://astronomy.stackexchange.com...ar-reactions-could-not-proceed-via-quantum-tu

This is a Stack Exchange thread with, again, no reference to any textbook or peer-reviewed paper that I can find.

 

[PeroK]

Then take that up with the physicists who worry about that stuff in cosmology and foundations.

All we have is your interpretation of they say and think. We had an interview with David Griffiths, and he made this very point:

"I think there are two villains here: (1) Physicists, who are (rightly) desperate to explain to the world the extraordinary, fascinating, and profound implications of quantum mechanics. But they are afraid of intimidating an audience that gags at the sight of an equation; they want to convey the excitement without the substance. So they resort to forced similes and grossly misleading metaphors (quantum tunneling means you can walk through walls

https://www.physicsforums.com/insights/interview-physicist-david-j-griffiths/

I'm with Griffiths on this one.

 

[DaveC426913]

It's more like there would be parts of the cosmos where the incredibly improbably happens on a regular basis. So coins turn up heads a thousand times in a row, dice roll sixes a million times, people walk through walls some of the time, etc.

No, that does not follow.

In some given part of the cosmos, some incredibly improbable event (singular, not plural) occurs.
In some other incredibly distant part of the cosmos, some other incredibly improbable event occurs.

True, for every incalculable number of improbable events that individually occur in incalculably distant regions of the cosmos, once in a blue moon, two improbable things might occur near each other.

Kind of like a two-time lottery winner. Do two-time lottery winners think they're broken physics?

In a thousand years of lotteries, we will look back and see that two-time lottery winners are, by-and-large not unheard of, so a three-time winner will not be shocking.

On an Earth that has a trillion year history of flipping coins, it should surprise no one when heads has come up a thousand times in a row sometime in their trillion year history.

 

[Quantum Waver]

All we have is your interpretation of they say and think. We had an interview with David Griffiths, and he made this very point:

Then I'll go find papers in which physicists do discuss unlikely probabilities with both QM and thermodynamics, and why they think it matters. Maybe it doesn't for David Griffiths, but you won't have only my interpretation if you would like the actual sources.

 

[Quantum Waver]

No, that does not follow.

In some given part of the cosmos, some incredibly improbable event (singular, not plural) occurs.
In some other incredibly distant part of the cosmos, some other incredibly improbable event occurs.

True, for every incalculable number of improbable events that individually occur in incalculably distant regions of the cosmos, once in a blue moon, two improbable things might occur near each other.

Kind of like a two-time lottery winner. Do two-time lottery winners think they're broken physics?

In a thousand years of lotteries, we will look back and see that two-time lottery winners are, by-and-large not unheard of, so a three-time winner will not be shocking.

On an Earth that has a trillion year history of flipping coins, it should surprise no one when heads has come up a thousand times in a row sometime in their trillion year history.

It does follow, because there's nothing stopping many events happening on a regular basis in some incredibly small part of the cosmos, whether it's branches/worlds or very, very far away. But since posters seem to think I'm misinterpreting what some physicists actually mean when they're not misleading the public, I will go find a paper to be sure.