Particle physics

Particle physics

 

Particle Physics is the branch of that describes the properties and interactions of subatomic particles. The generally accepted model in particle physics is known as the Standard Model. While the Standard Model has been quit successful it does not quite describe everything.

 

 



 

The Standard Model was developed by scientists from all over the world in the mid 20th century. The model has a total of 30 fundamental particles including 17 particles and 13 anti-particles for. These particles make up all of the observable matter of the universe but only 3 of them make up most of that matter. All fundamental particles are one of two types: fermions and bosons and the Fermions are further subdivided into quarks and leptons. This the basic concept in particle physics.

 

All particles except some Bosons have a corresponding ant-particle that usually has the opposite charge and spin of the other particle. The anti-particles of the particles that make up ordinary matter are known collectively as anti-matter because. Anti-atoms and anti-molecules are made of antiprotons, antineutrons, and positrons (ant-electrons).  When antimatter and ordinary matter meat they annihilate each other with 100% mass to energy conversion.

Particle physics does not tells  us about the conditions that would have existed in the early stages of the Big Bang if it did occur. Because of this particle physics actually causes a major problem for the Big Bang cosmology. It turns out that all of the observable Universe is made of ordinary matter, with antimatter being nearly totally absent however the Big Bang should have produced equal amounts of matter and antimatter but we see no evidence of the antimatter.

In particle physics the production of a particle of matter from vacuum energy it also produces the equivalent particle of antimatter. This is what would have occurred in the Big Bang since all that would have exited is vacuum energy.

 The first proposed explanation id based on the fact that an object made of antimatter would look the same as one made of matter it has been proposed that distant parts of the universe could be composed of antimatter and it would look the same. However there are two major problems with this idea.

When matter and anti-matter meet they annihilate each other in a burst of radiation. Since such annihilation would be continually occurring where regions of matter and antimatter meet and the resulting radiation should be detectable but it has never been observed. In addition because the fundamental particles of ordinary matter are charged and the equivalent antimatter particles have the opposite charge once produced matter – antimatter particle pairs would be attracted to each other where they would be annihilated. Preventing this from happening requires an unknown field that would pull mater and antimatter apart, other wise they would form a homogeneous mixture of matter and antimatter.

Immediately after the Big Bang there would be a massive amount of production and annihilation of matter and antimatter. Once the expanding universe cooled below the point where production would stop but the annihilation would continue. This process would continue until there was nothing left or that which was left was too thinly spread out to interact and such conditions could not produce the universe we live in.

Proponents of the Big Bang cosmology understand the problem and have proposed three possible ways around the problem.

1. That antimatter particles decay faster the their matter counterparts.
2. Some how there was an over production of matter over antimatter.
3. Some antimatter particles turned into matter particles.

The claim that antimatter particles decay faster than their matter counterparts is contrary to evidence since in all known cases particles and their anti particles have the same mean lifetime. Furthermore even if the particles that make up normal matter like protons and electrons decay at all their mean lifetime is so long that this idea could probably never be tested.

The claim that some how there was an over production of matter over antimatter is also contrary to evidence since in all known cases matter and antimatter particles are produced together.

The claim that some antimatter particles turned into matter particles is totally contrary to evidence. The closest to this that has been observed are neutrinos becoming different types of neutrinos but not anti neutrinos.

All of the proposed solutions to this problem with the Big Bang are totally speculative and not one is based on observable fact. Perhaps the best solution is that the Big Bang is not how the Universe really began.



Video on Faster Than Light Neutrinos

There’s a common mistake that this is a problem for relativity but it is not. Relativity forbids is accelerating up to and past the speed of light but does not for bid particles that naturally travel faster than the speed of light. Such particles have been speculated about for decades under name tachyons.

The only real difficulty is that neutrinos have a small but real rest mass and so should not be traveling faster than the speed of light. In that case the issue is most likely with our understanding of neutrinos and relativity.

Quantum Mechanics allows particles to skip part of space instantly and so could be clocked at faster than the speed of light while going sub-light through the space it actually goes through. This is the most likely explanation of this observation given calculations from India.  See Flaw Found in Claim of Faster Than Light Neutrinos

Still no Higgs Boson

 Scientists at CERN’s large Hadron Collider have yet find the Higgs Boson after yet another try this week. They did however narrow the mass range where it may be found to between 115 billion electron volts and 127 billion electron volts. One team got a hint pointing to 125 billion electron volts and the other team got a hint pointing to 126 billion electron volts. They expect to get a final answer some time in 2012.

Among the possible answers is that the Higgs boson is not there to find. If the Higgs boson is shown not exist it will force a rethink of some aspects of particle physics theory. The Higgs boson is supposed to be what gives all other particle their mass but if the Higgs Boson is shown not to exist it will require a new theory. This is not an uncommon part of science in fact it is critical to the process. It’s just nicer as a scientist when you get it right.

How Neutrinos Going Faster than Light Posses no Problem for the Theory of Relativity.

The recent report by CERN that they measured neutrinos going faster than the speed of light by about 20 parts per million has made quite a stir. Given that the speed of light is 299,792,458 m/s these neutrinos were going 6 km/s faster than light which could easily be an experimental error.

It would not be a problem for Special Relativity since not traveling at or faster than the light only applies to particles with a real non zero rest mass. A particle like a photon that has a zero rest mass travels at the speed of light. Particles that travel faster than light have been speculated for years under the name tachyons. Tachyons would have a negative imaginary rest mass giving it a real non zero mass at speeds above the speed of light. It would however be incapable of being decelerated to the speed of light below it.

Also quantum effects like quantum tunneling provided another way around the light barrier by allowing particles to instantly skip over an area of space without actually going through it while traveling sub light through the space it does go through thus not violating Special Relativity.