# Homework Help: Question about photons

1. Apr 7, 2005

### Raparicio

Hello All,

I have a question about photons. In A. Einstein ecuation (about Lorenzt transformation), there's a square root of c^2-v^2. My question is about what is the v represented: a vector? Only one direction vector? Only his module?

best reggards.

R.apaparioscios.

2. Apr 7, 2005

### Nylex

Do you mean (1 - β^2)^1/2, where β = v/c? It's just the size of the velocity, so the modulus.

3. Apr 7, 2005

### Raparicio

Ok

It's right. Is the modulus, but: could be a paravector???

4. Apr 8, 2005

### Nylex

What's a paravector?

5. Apr 8, 2005

### Raparicio

Paravector

Hello now,

A paravector is a generalization of a vector, with a non-vectorial part and a vectorial part (like complex numbers have Real + Complex number). There are more generenalizations of vectors, like hypercomplex of hamilton, and the most general interesting now is Clifford Algebras and Geometric Algebra.

Could say that a vector is a paravector without escalar part in this example.

my best reggards.

6. Apr 8, 2005

### dextercioby

You'd need a new theory for that.For the Theory of Relativity developed over the last exactly 100 years,that "v" from $\beta$ or $\gamma$ is a scalar,namely $\left|\vec{v}\right|$...That "v" has nothing to do with photons,of course...

Daniel.

7. Apr 8, 2005

### marlon

the v is just an ordinary velocity-vector. It has three dimensions or equivalently it has three components, just like in the case of Lorentz transformations. That's all. The v² is the magnitude of this vector which is determined by calculating the scalar product of this vector with itself.

The v is the velocity of one frame of reference to another...
marlon

8. Apr 9, 2005

### Raparicio

Paravector

Could be the velocity, a paravector or multivector, and this 'v' its module???

9. Apr 9, 2005

### dextercioby

It could iff u changed the whole theory.It could be pseudovector,the trace of a rank 658 tensor,etc...

Daniel.

10. Apr 9, 2005

### Raparicio

Whole theory???

Daniel,

What whole theory?

11. Apr 9, 2005

### Nylex

Maybe he means SR, I dunno.

12. Apr 9, 2005

### dextercioby

Yeah,change SR,you'll need to change GR as well.For the time being,they are successful theories and these theories address the velocity in the "gamma-factor" as the modulus of an ordinary 3-vector...

Daniel.

13. Apr 9, 2005

### Raparicio

14. Apr 15, 2005

### Raparicio

Meaning of SR and GR

I'm sorry for my ignorance. What means SR and GR?

15. Apr 15, 2005

### dextercioby

Special Relativity and General Relativity.

Daniel.

16. Apr 15, 2005

### Raparicio

Ok

Dear Daniel,

What I say is, what to unify SR an GR, we need to think the same way in both, and Geometrical Algebra provides a new tools to face it. If we take a multivector and apply a generalization of the Bertrand Russell circle, there are very interesting insights.

But this is very confusing to me.

Thanks another time.