I have 2 Physics question.

[nec209]

1. What is energy conditions known has Casimir effect.

 

2.The Higgs boson why do some say it is force not a particle ?

 

Why it's important: For decades, physicists have used a theory known as the Standard Model to explain the interactions of subatomic particles, and the theory works beautifully. It's guided our way through the world of nuclear power, television, microwave ovens and lasers. One problem: The theory needed something extra to explain why some particles have mass and some don't. Back in the 1960s, physicist Peter Higgs and his colleagues proposed the existence of a mysterious energy field that interacts with some particles more than others. That field is known as the Higgs field, associated with a particle called the Higgs boson.

 

http://cosmiclog.msnbc.msn.com/_news/2011/12/13/9402473-higgs-vs-hype-a-mini-guide

[ajb]

1. What is energy conditions known has Casimir effect.

 

The Casimir effect can create local negative energy densities.

 

In classical general relativity we have what are known as energy conditions. There are several different versions, but the basic idea is that classically energy and mass is always positive. One can use these conditions to decide if some matter content is physical or not.

 

However, as soon as quantum effects are added the situation becomes less clear. It is just about impossible to have a quantum theory that does not violate the energy conditions.

 

To describe all this more carefully requires come knowledge of general relativity as well as classical and quantum field theory.

 

 

2.The Higgs boson why do some say it is force not a particle ?

 

This has been discussed by me in another thread.

 

The basic point is that the Higgs is a boson and fundamental bosons are usually associated with forces. But the Higgs is not a "vector boson" and so does not come from some deep mathematical principle, namely gauge symmetry. Thus it looks more like matter, but fundamental matter is usually fermionic.

 

A little more technically, the coupling of the Higgs to the (massless) quarks and leptons is a Yukawa coupling. This looks more like an effective force, but it is very ad hoc.

 

In reality, I don't think it matters too much if you think of it as a force or as matter. You know how to deal with it in the theory and this is probably enough.

[swansont]

1. What is energy conditions known has Casimir effect.

 

If you solve the particle-in-a-box problem, you find that the solutions have the form of [math]E_m = (n + \frac{1}{2})\hbar\omega[/math] for each standing-wave mode (m) of oscillation.

 

This means that even when n=0 (no particle of that energy), there is still energy there. But of you use conducting surfaces, because of the boundary conditions on the electric fields means that some of those modes can't exist. That is, the energy of the system with the walls is less than the zero-point of free space. There is an energy gradient, so there is a force on the conductors.