If a particle can decay into a lighter set of particles and still obey all of the conservation principles, they will. The heavier they are, the more they're going to decay and the more "options" they have to decay. An electron isn't going to do anything because there is nothing lighter than an electron that still carries charge, etc. Something much heavier, like a free neutron, will fall apart into a proton, an electron, and an anti-electron neutrino.
These particles have options galore as to what they can fall apart into being, and so they do, and with great haste.
I know nothing about physics as it is not my domain. So I don't know if what you're saying is true or not. But if it is, I find that notion somewhat poetic.
For the sake of my own edification, I'd like to follow this up with a few somewhat seemingly dumb questions if you dont mind:
Is it the case that a given particle is trying to settle into a "lowest energy state" possible? I am not using physics terms here. More like conceptually, are these particles, due to the number of options available to them, decaying into the lightest stable variant allowed by the laws of physics? if that is the case, then could we perhaps find ways to engineer structures within which these particles last for a whole lot longer than they should (on a human timescale)? And what is stopping us from doing that? is it the energy cost associated with such a structure/device or is there a more fundamental reason we cant do that?
> Is it the case that a given particle is trying to settle into a "lowest energy state" possible?
Not exactly. Energy is conserved during these decays. In fact, energy is conserved during all physical processes, so the "lowest energy state possible" is a little bit of a white lie. What makes it a white lie is that it is a very good approximation to the truth for thermodynamic systems, i.e. systems consisting of large numbers of particles. But for quantum systems, it is no longer a good approximation. In quantum systems, what happens is that you have a wave function that describes all of the possible states a system can be in. The more mass the system contains, the more possible states there are in its wave function, and so the more likely it is to end up in some state other than the one it started out in.
It is even possible for the process of decay to reverse itself, and for the constituent particles to come back together and reconstruct the original, but for that to happen all the constituents have to be brought back together, so as a practical matter this never happens spontaneously in nature. In fact, that is the whole reason for building the LHC -- to make particles (protons) come together and make high-mass systems which then decay in interesting ways.
> are these particles, due to the number of options available to them, decaying into the lightest stable variant allowed by the laws of physics?
Not the lightest stable variant, just to one of the possibilities described by that particle's wave function. These will always be subject to the constraints of conservation laws, so the decay products will always be lighter than the original. But which particular set of possible decay products is actually produced in any given decay event is fundamentally random.
> if that is the case, then could we perhaps find ways to engineer structures within which these particles last for a whole lot longer than they should (on a human timescale)?
No. The wave functions for particles are fixed by nature. They are what give particles their identities. They cannot be engineered. The only thing that we can engineer is the arrangement of particles. Particles are like Lego bricks. You can stick them together in lots of different ways, but you can't change the shape of a given brick. Sometimes quantum Lego bricks fall apart spontaneously, but there is no way to control that.
I thought in q field theory there is on a fundamentally level no particle. They are artificial excite state in a field. Hence the all possible state possibly as it is not the particle as this is already in a state, but a wave. The interaction of fields … wonder if we reframe the q as CSB we have or find new operators to …
Neutrons don't decay while being part of a stable atom, because the atom has actually less energy than the sum of the constituents -- the difference is the binding energy. Look at deuterium, for example. It has a mass of 2.0141 u. A proton alone is 1.0073 u, and a neutron is 1.0087 u. Deuterium is lighter than the mass of proton + neutron. It's also slightly lighter than two protons, so the neutron cannot decay without external energy input.
This actually brings me to a physics question I've had for a while and if it is unrelated, please feel free to ignore it as I might be mixing concepts.
Both fusion and fission release energy when they occur. Which seems somewhat weird to me. Is it the cases that the reason a stable atom has less energy than the sum of its parts (as you pointed out) is because it gave off some energy during the fusion process?
Pretty much. To simplify a bit: the most stable atom is iron-56 anything lighter can be fused and anything heavier can be split to release energy. Essentially after iron the forces that bind atoms together start to lose out to the repulsion between it's constituents, which makes heavier atoms more and more unstable.
This is also why stars that start to fuse iron together will start to cool down.
Edit:
If neutron is likely to decay into. Why *neutrons* dont decay while being part of an atom?
(Wouldn’t this be example of a structure that prevents decaying?)
As another not-physicist who is interested in physics, I've found the articles/explainers at Of Particular Significance very helpful. There are a few on particle decay, and I think that these two provide a longer answer to your questions:
> Is it the case that a given particle is trying to settle into a "lowest energy state" possible?
It's more accurate to think of the energy "spreading out" (remember that mass is a form of energy too, since E=mc^2). The energy can rearrange (subject to conservation laws), between being one massive particle, or several lighter ones (in fact there's a superposition of possibilities, because quantum).
In principle the probability of switching back-and-forth is equal, e.g. the probability of particle A decaying into a B+C pair, is identical to the probability of a B+C collision producing an A. However, most of the directions those light particles can take will result in them flying apart rather than colliding; that spreads out the energy, so it can no longer switch back into the massive particle configuration.
Note that this is essentially the first and second laws of thermodynamics (energy is conserved, and concentrations tend to "spread out" over time)
Sometimes they will have intermediates, which then decay, and then those products decay, and so on. That's quite common. Eventually they just ... fall apart. The more options, the faster. The greater the energy stepdown, the faster, by which I mean "can it release a gamma? Or fall apart into some much smaller things?"
However, it is independent of "nearby" structure, where nearby is any distance larger than the nucleus. So, no, we cannot contain these particles within anything to prevent their decay, it is like trying to build a bouncy castle around a hand grenade in hopes that it won't go off.
Note that there is an apparent delay in decay, from our perspective, when particles are moving very fast, like a relativistic muon lasting longer (although still a very brief period of time by our standards) than expected, simply due to special relativity. But here this also would not help.
Things fall apart, the center cannot hold, and so on.
It is the case that particles always try to settle into the lowest energy, and the more options they have the faster. We may be able to engineer places where they're stable, like in the example from my grandparent of a neutron. They are unstable since their mass is greater than the mass of a proton and an electron combined, but they're stable in all common elements we're used to. So much so that we think of radioactive elements as the exception, but (mostly) all that's happening there (in beta decay) is a neutron decaying.
I'm not an expert, but I'd imagine making a stable situation for a heavier particle much harder than just making an atom, and the fine grained control is even hard still.
>>trying to settle into a "lowest energy state" possible?
What if its actually the reverse: Its attempting and succeeding to be the most it can be given the eddy of forces around it - the particle is "becoming" - not "falling apart"
an interesting analog is if you have a house of cards on a table, it's in a way "trying to settle" into the lowest energy state possible which is post collapse all the cards on the table! But it's also not "trying" to do anything, it's just vibing / vibrating and what ever happens to it happens to it :)
Depends entirely on the particle. A free neutron might have a half life of around twenty minutes. These pentaquark particles, well, nanoseconds are too long to describe, by about ten orders of magnitude.
Some of the heavy elements assembled in colliders are described as decaying so quickly that one side of the nucleus is coming together even as the other side is disintegrating, a sort of brief wave of existence traveling at nearly the speed of light across this thing that has been forced together and wants to fly apart.
An example of something considered to be "slow" is the muon. You could kind of thinking of it as a heavy electron (though that hand waves away a lot). It has a mean lifetime of 2.2 μs - which is fairly slow.
Also note that they're not rare and there's a fair bit of neat science behind that too.
> About 10,000 muons reach every square meter of the earth's surface a minute
There's also neat stuff with time dilation and muons ( http://hyperphysics.phy-astr.gsu.edu/hbase/Relativ/muon.html ) - there should be far fewer observed muons at the surface if muons didn't experience time dilation from their relativistic speeds.
> The historical experiment upon which the model muon experiment is based was performed by Rossi and Hall in 1941. They measured the flux of muons at a location on Mt Washington in New Hampshire at about 2000 m altitude and also at the base of the mountain. They found the ratio of the muon flux was 1.4, whereas the ratio should have been about 22 even if the muons were traveling at the speed of light, using the muon half-life of 1.56 microseconds. When the time dilation relationship was applied, the result could be explained if the muons were traveling at 0.994 c.
(note: mean lifetime and half-life are different numbers)
The thing here is that 2.2 μs is slow, but even with something that is that fast (on a human scale), there's a lot of neat science that can be done with them. They've even made muonic atoms (where the electron is replaced by a muon) https://en.wikipedia.org/wiki/Exotic_atom ... and that leads to possibilities on lowering fusion temperature ( https://en.wikipedia.org/wiki/Muon-catalyzed_fusion ) because the muon is much closer to the nucleus in its ground state.
If a particle can decay into a lighter set of particles and still obey all of the conservation principles, they will. The heavier they are, the more they're going to decay and the more "options" they have to decay. An electron isn't going to do anything because there is nothing lighter than an electron that still carries charge, etc. Something much heavier, like a free neutron, will fall apart into a proton, an electron, and an anti-electron neutrino.
These particles have options galore as to what they can fall apart into being, and so they do, and with great haste.