Seemingly odd quantum tunneling

[DanteKennedy]

Question:
Large objects (say, a sofa) are made of individual atoms, and those atoms are made of subatomic particles. From what I know, smaller particles in principle have higher chance for quantum tunneling than large object and the probability gets exponentially smaller as mass increases. So why don't most object "decay" slowly because the individual particles that made it got tunneled one by one?

Note:
I don't have any advanced knowledge about quantum physics, so it would be good if someone can correct my knowledge if there's any mistakes
(And sorry for bad English)

 

[PeterDonis]

why don't most object "decay" slowly because the individual particles that made it got tunneled one by one?

Because if the particles are bound inside a large object, they're not free particles, and all the stuff you refer to about tunneling and the probability of it assumes free particles. More precisely, it assumes particles that, while they might be "bound" inside a potential barrier (and have some nonzero probability to tunnel through the barrier), they're not bound to other particles of the same type that are also inside the same barrier.

All this is heuristic, btw, because to really discuss all the reasons behind this would mean going well beyond High School level.

 

[DanteKennedy]

while they might be "bound" inside a potential barrier (and have some nonzero probability to tunnel through the barrier), they're not bound to other particles of the same type that are also inside the same barrier.

Does this mean that it can also be applied to molecules (which made of small amounts of atoms) where the bond prevents the molecule to broke up from quantum tunneling?

 

[PeterDonis]

Does this mean that it can also be applied to molecules (which made of small amounts of atoms) where the bond prevents the molecule to broke up from quantum tunneling?

If the scenario is such that you can consider the molecule as a "particle", it has some nonzero probability to tunnel through a barrier, though the probability will be smaller than for, say, a single electron.

 

[Paul Colby]

Tunneling doesn’t (can’t) violate energy conservation. A stable molecule (bound group of atoms) has a lower net energy than the same particles separated into two or more free groups. If this were not the case, the molecule would be unstable and could decay or break apart via tunneling.

 

[DanteKennedy]

A stable molecule (bound group of atoms) has a lower net energy than the same particles separated into two or more free groups. If this were not the case, the molecule would be unstable and could decay or break apart via tunneling.

But what happens during spontaneous molecule breaking? And why particles have lower net energy by forming molecules rather than being separated? Is it always the case?

 

[DanteKennedy]

If the scenario is such that you can consider the molecule as a "particle", it has some nonzero probability to tunnel through a barrier, though the probability will be smaller than for, say, a single electron.

Interesting. So partial tunneling doesn't exist? (Only a fraction/several particles from a larger object initiated tunneling while the rest of the object are intact)