The Naked Scientists

The Naked Scientists Forum

Author Topic: What is reason why some particles are stable and most unstable  (Read 2514 times)

Offline dhjdhj

  • Full Member
  • ***
  • Posts: 78
  • Thanked: 1 times
    • View Profile
If as it seems energy can create many different types of sub-atomic particles. Why do some, when outside of the sanctity of an atom immediately decay?and others such as electrons, protons, and neutrinos remain stable virtually for ever. Could it be that the stable particles provide evidence that there is a much smaller particle creating them into their stable structure, a bit like a mini atom, and that they can also combine to form unstable structures?


 

Offline puppypower

  • Hero Member
  • *****
  • Posts: 553
  • Thanked: 42 times
    • View Profile
One theory, I proposed in the past, are the sub particles, when part of the proton, for example, are highly time dilated. They formed at the beginning of the universe when space-time was highly time contracted and retained the time dilation. This gives the proton a very long life in our reference; billions of years.

When these sub particles are released in particle colliders, their new short life is a reflection of their original time dilation being disrupted, due to the relativistic speeds and collisions.


 

Offline evan_au

  • Neilep Level Member
  • ******
  • Posts: 4091
  • Thanked: 243 times
    • View Profile
It is said that, in Physics, an event must happen if it is not forbidden by a law (provided that you wait long enough).

The laws governing quantum interactions are given by quantum numbers.

One of these laws is conservation of energy - a particle can't only decay into a set of particles with lower (rest) energy.

But this decay must also obey laws around conservation of charge, conservation of spin, etc. The weak nuclear force plays by a looser set of rules than the strong nuclear force.

And for low energy decays governed by the weak nuclear force, you sometimes need to wait a long time - perhaps billions of years!

It is still unknown whether the proton is completely stable, if you are prepared to wait 1050 years!

See: http://en.wikipedia.org/wiki/Quantum_number
 

Offline Atomic-S

  • Hero Member
  • *****
  • Posts: 928
  • Thanked: 18 times
    • View Profile
Science  now believes that protons, mesons, and neutrons are in fact composed of smaller particles, namely quarks and gluons, a fact which in itself does not much illuminate the question of stability.  I am not sure there is a simple answer to the why of stability. Reduced to simplest terms, an unstable system requires that there be at least two different options for the distribution energy that comprises the system, and that the stable state be substantially more probable than the unstable state. (I was going to say, that the nonkinetic energy of the stable state be less than that of the unstable, but that does not take into account the fact that the stable state could concievably revert to the unstable state due to the time-reversability of the equations, such as two photons spontaneously turning themselves into an electron and positron, so that we might on this basis consider the photon to be an unstable particle; however the operative principle here would be that such events are rarely seen not because they are impossible, but because they are highly inprobable under most circumstances of observation.) So, with that view, for the possibility of an unstable particle, there must exist an alternative mode of the existence of its energy that is consistent with the conservation of everything than needs to be conserved, and the probability of transitioning to that state must be significant in comparison with the reverse transition. Now how do we apply that to the list of specific particles and their specific half-lives? That is where things get difficult, undoubtedly requiring a detailed analysis of possible quantum states that the universe can support, and I don't know that anyone has been successfully able to do this. It would appear to be on the cutting edge of research right now, involving understanding things such as the Higgs field, string theory, etc.
 

Offline Atomic-S

  • Hero Member
  • *****
  • Posts: 928
  • Thanked: 18 times
    • View Profile
Undoubtedly, very simple particles are stable because there exists no simpler state in which they could exist.  On the basis of that, we might expect that more complex particles would eventually all disintegrate into the simplest possible particles; but we find that that is not necessarily the case, and as to why, that may well require a detailed analysis on a casse-by-case basis.
 

Offline dhjdhj

  • Full Member
  • ***
  • Posts: 78
  • Thanked: 1 times
    • View Profile
Thanks for the replies. I am not sure about time dilated particles and it would surely be impossible to prove experimentally. The reference to the answer on quantum numbers. I did go to the web site suggested and others and it did not really answer the question. It did show how the mathematics of the standard model could predict decay and stability, but not why they were stable or not. I was asking about the causality of stability. I do like atomic s's reply and wonder whether it is possible for there to be a single very very small fundamental particle to be the building block for all other particles. Would that necessarily violate the mathematics of the standard model? It would of course be unstable and even smaller than an electron nuetrino . I would exclude massless particles like a photon.
 

Offline evan_au

  • Neilep Level Member
  • ******
  • Posts: 4091
  • Thanked: 243 times
    • View Profile
Quote from: dhjdhj
I am not sure about time dilated particles
Particle accelerators like the LHC often produce particles with very high velocity (close to the speed of light in a vacuum). This results in a time dilation, as seen by observers on the surface of the Earth. These particles are observed to decay as they would "at rest", but it just takes longer.

Quote
smaller than an electron neutrino
It is now known that the electron neutrino "oscillates" between three states, the electron, muon and tau.
I would not call this a "decay", as it is a "superposition" of three states; you always have some probability of finding all 3 neutrino types.
This discovery won the 2015 Nobel Prize for Physics.
See: https://en.wikipedia.org/wiki/Neutrino_oscillation

Quote
I wonder whether it is possible for there to be a single very very small fundamental particle to be the building block for all other particles
This was the logical basis of the concept of an atom, as deduced by Democritus.
https://en.wikipedia.org/wiki/Democritus#Atomic_hypothesis

Quote
a single very very small fundamental particle...Would that necessarily violate the mathematics of the standard model?
To construct particles with electric charge, this fundamental particle must have non-zero electric charge.
To construct bosons, this fundamental particle must have non-zero boson number.
etc

This does not sound like a very very small particle.

Note that we are describing particles in the universe as we see it today. It is thought that at the very high energies thought to exist in the early stages of the Big Bang, the different forces we see today may have been a single, unified force. In this environment, the set of stable particles is thought to be very different from what we see today, and may have been very massive compared to the stable particles we see today.
 

Offline dhjdhj

  • Full Member
  • ***
  • Posts: 78
  • Thanked: 1 times
    • View Profile
Thanks I know particles are subject to time dilation. I was referring to the hypothesis put forward. I am also aware of Democritus and his atomon theory, which sounds pretty logical to me just not small enough. I was only using the electron neutrino as an example of how small the particle would need to be, but I did find the article you highlighted very interesting. Now charge is an interesting one. You state that the particle would need to have a charge, but what exactly is a charge? Could it be caused by rotation, clockwise being say positive and anti-clockwise being negative when related to the prominent gravitational or electro-magnetic field? It seems to me to be pretty small when compared to the other forces within the atom so is it impossible for it to originate with a tiny fundamental particle and for composites to have an odd number for a negative charge, a contra-rotating odd number for a positive charge and an even number for a neutral charge. Could a positron be an upside down electron for instance turned the right way up as it hits the earth's gravitational field? 
 

Offline evan_au

  • Neilep Level Member
  • ******
  • Posts: 4091
  • Thanked: 243 times
    • View Profile
Quote from: dhjdhj
What is reason why some (subatomic) particles are stable and most unstable
The same reason that some chemicals are stable and most unstable: In nature, objects tend to find the state of lowest energy.

If they have excess energy, they tend to fly apart (disintegrate).
 

Offline PatrickPowers

  • First timers
  • *
  • Posts: 3
    • View Profile
One theory, I proposed in the past, are the sub particles, when part of the proton, for example, are highly time dilated. They formed at the beginning of the universe when space-time was highly time contracted and retained the time dilation. This gives the proton a very long life in our reference; billions of years.

When these sub particles are released in particle colliders, their new short life is a reflection of their original time dilation being disrupted, due to the relativistic speeds and collisions.

This is crackpot hogwashery. 

Some particles such as the electron and neutrino do not decay because there are no simpler particles to decay into.  The proton is made of simpler particles, but seems not to decay.

Neutrons decay when outside the nucleus.  I don't know why they don't decay inside the nucleus.

There is an uncertainty relationship with particle rest mass and lifetime.  The more certain the rest mass, the more uncertain the lifetime, and vice versa.  So electrons and protons have very certain masses and very uncertain lifetime, so uncertain that we can't even assign a number to their half-life and instead say "infinity."

The shortlived (like nanosecond) particles have uncertain rest masses, and hence certain lifetimes.  It is virtually certain that the lifetime will be less than a second. Such particles are very useful for communication between the more stable particles.
 

Offline A Davis

  • Sr. Member
  • ****
  • Posts: 106
    • View Profile
I don,t know really, the only example I can think of in nature is hot stars they change their solution and blow up quicker than colder ones they keep on trying to form a lower energy solution. particles do the same. One could say temperature does play a part with particles but I am not sure this is true, higher frequency solution inside the patricle should have higher tempetatures just like planets and the surface solution being at ambient temperatue . Difficult to prove if any one can do it good luck to you.
 

Offline dhjdhj

  • Full Member
  • ***
  • Posts: 78
  • Thanked: 1 times
    • View Profile
The fact that neutrinos can oscillate between its three flavours would seem to me to suggest that they might be composed of something smaller. Atoms also have a kind of three flavours in their solid, liquid and gaseous states which must be caused by some kind of rearrangement of their constituent particles. As it also seems that origin of the neutrinos mass is outside the explanations of the standard model my idea of a neutrino being a kind of mini atom doesn't appear too stupid. It seems logical to me that fundamental particles should be unstable, but able to form together to create either stable or unstable composites. Also given how difficult it is to break open an atom, it would be pretty impossible to break open any other stable particle and yet flavour oscillation in neutrinos occurs quite readily. Is there any evidence of other flavour oscillation?
 

The Naked Scientists Forum


 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums