Why do more big or small particles not exist in the Universe?

[alpha2cen]

After inflation there has only existed five particles in the Universe, i.e., electron, proton, neutron, neutrino, photon. I am wondering about why there is not existence more small or big particles. Are more small or big particles unstable to exist? Do we have any theory?

Edited July 14, 2011 by alpha2cen

[pantheory]

After inflation there has only existed five particles in the Universe, i.e., electron, proton, neutron, neutrino, photon. I am wondering about why there is not existence more small or big particles. Are more small or big particles unstable to exist? Do we have any theory?

As free massive particles there are only two major players, electrons and protons. Neutrons only last about 11 minutes in free space and neutrinos are only questionably massive and aren't known to be able to combine with anything. Positrons are known to exist in vast quantities surrounding the galactic core of the Milky Way and maybe similarly surround the centers of other galaxies maybe extending out radially from the center about 35 thousand light years.

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Edited July 14, 2011 by pantheory

[granpa]

http://en.wikipedia.org/wiki/Neutrinos#Mass\

 

The Standard Model of particle physics assumed that neutrinos are massless, although adding massive neutrinos to the basic framework is not difficult. Indeed, the experimentally established phenomenon of neutrino oscillation requires neutrinos to have nonzero masses

 

there exists at least one neutrino mass eigenstate with a mass of at least 0.04 eV

 

In July 2010 the 3-D MegaZ experiment reported that they had measured the upper limit of the combined mass of the three neutrino varieties to be less than 0.28 eV.

[alpha2cen]

Present theory.

 

Inflation ----> matter + anti matter -------> matter ( electron, proton, neutron, photon, neutrino), anti matter disappearing.

 

Can we see same phenomena at the LHC?

 

collision ------> matter + antimatter ------> -------> electron, proton , neutron, photon, neutrino

[ajb]

After inflation there has only existed five particles in the Universe, i.e., electron, proton, neutron, neutrino, photon. I am wondering about why there is not existence more small or big particles. Are more small or big particles unstable to exist? Do we have any theory?

 

 

There may well have been more types of particles in the early Universe than we currently can detect using colliders. For example we have supersymmetry that predicts that every particle has another particle partner . There is also the possibility of X and Y bosons associated with GUTs.

Edited July 14, 2011 by ajb

[Pageone03]

h I'm larry,,, I love this Forum. thanks for creating it,,,

[alpha2cen]

Do we have certain size or mass limitations to be an elementary particle ?

[ajb]

Do we have certain size or mass limitations to be an elementary particle ?

 

When the Compton wave-length is comparable to the particle's Schwarzschild radius then the particle would form a black hole. So it is believed that this would put a limit on the mass of particles.

 

If you do this (I suggest you have a go) then you will get the Planck mass (up to some [math]\pi[/math]s) as the limiting mass.

Edited July 15, 2011 by ajb

[granpa]

and the size is around teh planck length

Significance of the Planck Length / Rest mass / Gravitational field energy

Edited July 15, 2011 by granpa

[bombus]

Particles might not exist at all. It's just that the phenomena we are examining sometimes behave as if they are particles. They can also behave as if they are waves. They are neither, of course. Scientific examination of reality is ultimately all analogy. If it wasn't we wouldn't be able to conceptualize it - and still can't sometimes!

Edited July 17, 2011 by bombus

[ajb]

Particles might not exist at all. It's just that the phenomena we are examining sometimes behave as if they are particles. They can also behave as if they are waves. They are neither, of course. Scientific examination of reality is ultimately all analogy. If it wasn't we wouldn't be able to conceptualize it - and still can't sometimes!

 

 

Sure, really a particle is a mathematical abstraction, a useful way to describe the classical motion of "small" objects (small being defined by the scale of the physics). Again, waves are really a mathematical abstraction also.

 

By particle I assumed that alpha2cen's question was about elementary particles, not that the proton and neutron are elementary. This my be a source of confusion.

[alpha2cen]

By particle I assumed that alpha2cen's question was about elementary particles, not that the proton and neutron are elementary. This my be a source of confusion.

 

Protons and neutrons are not elementary particles.

Mathematically we can handle quark and gluon easily.

But at the experiment we could not have separated a quark or a gluon alone yet.

Edited July 17, 2011 by alpha2cen

[ajb]

Mathematically we can handle quark and gluon easily.

 

Well quantum chromodynamics is very difficult to work with outside of perturbation theory, which is where the interesting phenomenology lies. But anyway...

 

 

But at the experiment we could not have separated a quark or a gluon alone yet.

 

CERN and Brookhaven National Laboratory claimed to have created quark-gluon plasmas. I have not followed this closely (I should try to follow experimental physics better), anyone else know what the current thinking is on this?