Standard Model

[Amr Morsi]

More than 99.9% of the elementry particles are unstable of less than 10^-6 s life time. Is there any scientific theoretical justification?

[timo]

Is there a justification for your claim? I wouldn't even know of 1000 elementary particles being known in the first place.

[Marqq]

http://www.cassiopeiaproject.com/vid_courses3.php?Tape_Name=Standard

 

It's worth a look (and I'm pretty sure this one has the part about elementary particles). As to their instability, pay attention at the beginning of the series (if this is the right one).

 

(Sorry, my sound doesn't work, so I can't view the videos to make sure it's the right one)

[Amr Morsi]

I am saying elementry, not fundamental.

[mathematic]

What is the distinction you are making between "elementary" ad "fundamental"?

[Amr Morsi]

The funds are the 12 and the antiparticles.

[mathematic]

The funds are the 12 and the antiparticles.

 

What are the elementary that makes them any different?

[Ophiolite]

Amr, you appear to be using elementary in a non-standard way. In my (limited) experience the terms elementary and fundamental are equivalent. Could you give specific examples of individual, or groups, of elementary particles so we might better understand your intent. For example do you consider any nucleus to be an elementary particle? If not, do you consider an alpha particle to be elementary? ..... and I imagine you can see the difficulty there.

[Amr Morsi]

What a pion is considered to be?!

[imatfaal]

pions are bosons made up of a quark and antiquark (one up and one down for charged and two up or two down for uncharged). the quarks are fundamental or elementary (take your pick I think it is the same) - but the pi mesons are neither elementary nor fundamental

[Ophiolite]

What a pion is considered to be?!

It would be more helpful to quality discussion if you did not answer a question with a question. I shall repeat mine.

 

Could you give specific examples of individual, or groups, of elementary particles so we might better understand your intent. For example do you consider any nucleus to be an elementary particle? If not, do you consider an alpha particle to be elementary?

 

I am not trying to trip you up: I am trying to understand what you mean and to bring clarity to your assertions.

[Amr Morsi]

Thanks. That's enough.

[Ophiolite]

May I make two observations here? If you ask a question, indeed start a thread with a question, and then ignore a significant number of points made and questioned asked, that is rude. When you then break off half way through that discussion declaring you have had enough, leaving questions unanswered and points not addressed, then that is very rude. You should be aware that such behvaiour may discourage people from engaging in discussion with you in future. I'm sure this was not your intent, which is why I am taking the time to make you aware of the issue.

[Amr Morsi]

As per your regard, Sir, the discussion is not logical, from my point of viewing, if you would excuse me.

 

The thread is open, if you want to add. I am not to contribute in what I am not convinced of nor what is not ordered 'in my point of view'.

 

Sorry Man, if I was rude. Indeed, I didn't intend to hurt anyone.

 

Best Regards.

[csmyth3025]

More than 99.9% of the elementary particles are unstable of less than 10^-6 s life time. Is there any scientific theoretical justification?

In view of the ensuing discussion I'm guessing that you just pulled the "99.9%" figure out of your ear.

 

That said, you've sparked a question in my mind - which is: How many of the known elementary particles are considered stable?

 

As far as I know, protons and electrons are thought to be stable. Are all three types of neutrinos stable (in aggregate)? Free neutrons are not stable but are neutrons combined with protons (as in deuterium or helium) stable?

NOTE: From my reading of the Wikipedia article on Stable Isotopes, I'm thinking that neutrons are as stable as protons in at least 90 nuclides.

(ref. http://en.wikipedia..../Stable_nuclide )

 

And then, of course, there is also the question of whether quarks are stable.

 

In short, are there always going to be about the same number of protons, electrons and neutrinos as there were just after the big bang?

 

Chris

 

Edited to add NOTE and reference.

Edited July 23, 2011 by csmyth3025

[Amr Morsi]

Thanks Chris. I really appreciate this.

 

According to my knowledge that there are more than 350 elementry/primitive (nuclear/subatomic) particles, and they are being called as Particle-Zoo.

 

All of them have less than micro-sec decaying time (life-time) except protons/anti-protons [!], which are under debate [but mostly they do decay after 150s, or near].

 

Neutrinos are stable, I haven't heard rather than this. Quarks, not get isolated theoretically, or at least experimentally/physically, constitute hadrons (mesons/baryons) which decay mostly as mentioned before.

 

With respect to nucleons, as totally believed now, they exchange electrons (/neutrinos); protons and neutrons are, and that is why there is no problem of stability.

 

Electrons, positrons, neutrons and anti-neutrinos are the only known stable fundamental particles (may be protons/anti-protons). Thanks to not that even tau and muon (leptons) are unstable.

[csmyth3025]

Thanks Chris. I really appreciate this.

 

According to my knowledge that there are more than 350 elementary/primitive (nuclear/subatomic) particles, and they are being called as Particle-Zoo.

 

All of them have less than micro-sec decaying time (life-time) except protons/anti-protons [!], which are under debate [but mostly they do decay after 150s, or near].

 

Neutrinos are stable, I haven't heard rather than this. Quarks, not get isolated theoretically, or at least experimentally/physically, constitute hadrons (mesons/baryons) which decay mostly as mentioned before.

 

With respect to nucleons, as totally believed now, they exchange electrons (/neutrinos); protons and neutrons are, and that is why there is no problem of stability.

 

Electrons, positrons, neutrons and anti-neutrinos are the only known stable fundamental particles (may be protons/anti-protons). Thanks to not that even tau and muon (leptons) are unstable.

I can see now where you draw your pool of "elementary" particles. The lists of baryons and mesons are, indeed, long lists:

 

http://en.wikipedia....List_of_baryons

 

 

http://en.wikipedia..../List_of_mesons

 

Although these lists seemed to include hundreds of elementary particles in the 60's, they are now thought to be composite particles of more fundamental particles - quarks. Almost all of these composite particles were created briefly in high energy environments such as the particle colliders where they were first discovered:

 

The situation was particularly confusing in the late 1960s, before the discovery of quarks, when hundreds of strongly interacting particles (hadrons) were known. It turned out later that they were not elementary but rather composites of the quarks. The set of particles believed today to be elementary is known as the Standard Model

(ref. http://en.wikipedia....ki/Particle_zoo )

 

Chris

[Amr Morsi]

Great!!

[csmyth3025]

...Electrons, positrons, neutrons and anti-neutrinos are the only known stable fundamental particles (may be protons/anti-protons). Thanks to not that even tau and muon (leptons) are unstable.

(bold added by me)

 

I think you might mean neutrinos and anti-neutrinos. Free neutrons have a half life of about 885.7 seconds (~14.75 minutes).

(ref. http://en.wikipedia....ki/Free_neutron )

 

As far as protons and anti-protons are concerned, there is no observational evidence that they decay as far as I know. There are experiments that indicate a lower limit on the half-life of protons of nearly 10³⁴ years:

 

Recent experiments at the Super-Kamiokande water Cherenkov radiation detector in Japan gave lower limits for proton half-life, at 90% confidence level, of 6.6×10³³ years via antimuon decay and 8.2×10³³ years via positron decay.^[3] Newer, preliminary results estimate a half-life of no less than 1.01×10³⁴ years via positron decay.^[4]

(ref. http://en.wikipedia....mental_evidence )

 

Chris

[Amr Morsi]

For sure, I mean neutrinos.

 

O.K. Neutrons: 886s and Protons: 10³⁴s. I will bear this in mind, I promise.

 

Any way, they are proven to be consisting of Quarks and that they decay by weak force when interacting with other particles.

 

Thanks Chris. This is enough for me. I really APPRECIATED your contribution.

 

Regards / Amr morsi.

Edited July 24, 2011 by Amr Morsi

[csmyth3025]

For sure, I mean neutrinos.

 

O.K. Neutrons: 886s and Protons: 10³⁴s. I will bear this in mind, I promise.

 

Any way, they are proven to be consisting of Quarks and that they decay by weak force when interacting with other particles.

 

Thanks Chris. This is enough for me. I really APPRECIATED your contribution.

 

Regards / Amr morsi.

For those who are still following this thread, please note that although a proton half-life of 10³⁴ seconds is a very long time (~2.3 x 10¹⁶ x the present age of the universe), the lower limit given for the half-life of the proton in my previous post is ~10³⁴ years (~7.3 x 10²³ x the present age of the universe).

 

Out of curiosity, I'm wondering: Suppose one ignores effects such as protons being splattered by cosmic rays (or particle accelerators), smashed into neutronium in neutron stars or gobbled up by black holes. If one assumes that the fate of all the protons left over after the big bang is that they will decay with a half life of ~10³⁴ years, what percentage of those primordial protons are left today?

 

I tried to figure this out using the Wikipedia information on exponential decay ( http://en.wikipedia....ponential_decay ), but the math is beyond my limited comprehension.

 

My instinct is that if 1/2 of the original protons will have decayed in 10³⁴ years, then 0.5/(7.3×10²³) will have decayed by the present time and this would result in about 0.9999999999999999999999993150684 of all the original protons still being around today.

 

Can anyone give me a correct way of calculating this?

 

Chris

[Amr Morsi]

Strong force is also a contribute in some/all decays? Or, just a change of color/flavor?

[Amr Morsi]

Confirmation Declared. Notes are sufficient and indicative.

 

Amr Morsi.