# A photon with spin 2?

1. May 11, 2010

### afcarval

Dear all,

How can you tell if it is spin 1 or 2 ?

Thanks,
Alex

2. May 11, 2010

### ansgar

1 since it transforms as a vector under lorentz transformations (or rather the four potential transforms as a vector)

3. May 11, 2010

### afcarval

Dear ansgar,

Can you explain the detection and nature of the four potential?

"it" is the "four potential" that transforms as vector under Lorentz transformations?

The spin is 1 because the vector is a tensor of order 1?

Thanks,
Alex

4. May 11, 2010

### ansgar

yes vector = tensor rank 1

http://en.wikipedia.org/wiki/Electromagnetic_four-potential

5. May 11, 2010

### afcarval

Dear ansgar,

What kind of tensor of rank 2 can you expect after a Lorentz transformation?

Is the "four-potential" enough to describe the signals detected?

cheers mate,
Alex

6. May 11, 2010

### sheaf

Assuming by "the signals" you mean the electric and magnetic fields, then it's more than enough (gauge freedom).

7. May 11, 2010

### afcarval

Dear sheaf,

So the "four-potential" detects electric and magnetic fields.
The matrix consider the electric and magnetic fields has independent signals?
Is the magnetic field independent of the magnetic field?

Cheers,
Alex

8. May 11, 2010

### ansgar

you mean

Is the ELECTRIC field independent of the magnetic field?

no you can see that from the very definition of E and B ...

9. May 11, 2010

### afcarval

Dear ansgar,

yes, I meant: Is the electric field independent of the magnetic field?
thank you!

cheers mate,
Alex

10. May 11, 2010

Staff Emeritus
Afcarval, what's your background in physics. I get the impression that these answers aren't pitched at the level you're expecting.

11. May 11, 2010

### afcarval

In my degree I had some physics, in my master too and in my PhD also... but not specific in physics. Only a course in Quantum Monte Carlo...

My basic question: can you detect one photon with spin 2? Why?

Thanks!
Alex

12. May 11, 2010

### ansgar

there is no such thing so how can you detect it?

13. May 11, 2010

### afcarval

Dear ansgar,

So you are telling me that by definition is not a photon?

But can you model the response in order to have a photon with spin 2?

Another way to put the question. Can you have a particule with spin 2 without electromagnetic perturbation?

Why?

Thanks,
Alex

14. May 11, 2010

### ansgar

you can detect photons with a combined angular momentum and spin and parity as you want, that is just the multipole expansion..

15. May 11, 2010

### afcarval

Dear ansgar,

Can you explain better?

You are telling me that: if you want, you can detect a spin 2 for photons?

Thanks,
Alex

16. May 11, 2010

### ansgar

you have not defined properly what you mean with all of this. photons can have angular momentum J which is the sum of L and S

I can not explain better since what you really need is to define what and why you are asking this for and a couple of textbooks

17. May 11, 2010

### afcarval

Dear ansgar,

One last question.
In the detector and in the signal analysis can you tell the difference between a photon with spin 2 and a graviton?

Cheers mate,
Alex

18. May 11, 2010

### ansgar

I kknow that there was some mumbo jumob behind all of this

gravitions does not interact electromagnetically

19. May 11, 2010

### afcarval

Dear ansgar,

Mumbo jumob? They are simple questions...

The question:
Can you really have a particule with spin 2 without electromagnetic perturbation?
Can you explain why?

Or are they dogmas?

cheers mate,
Alex

20. May 11, 2010

### twofish-quant

It seems that at some level you can model gravitons seem to be modeled by spin 2 particles.

Not really.

Observations. Some particles we see existing. Some particles we don't.