# Redshift and Zeeman effect .

1. Jul 6, 2010

### cragar

Lets say we emit a photon from the ground out towards the sky , and as the photon travels away from earth it gets red-shifted . In stead of canceling the shift by using the Doppler effect like they did in the pound-rebka experiment , we use the zeeman effect to alter the
discrete energy levels of the electron orbiting the atom so that the atom will absorb the photon after the red-shift , and we assume the original photon at ground level was emitted from an atom that had a difference in energy from n=2 to n=1 , and then we cancel the shift with the zeeman effect so that the photon will excite the atom after the shift from n=1 to n=2 .
Would this imply that clocks tick at different rates in different B fields . Excluding the gravitational effect from the B field . Or am i missing something here .

2. Jul 6, 2010

### Eynstone

It depends on where the second atom is located . Two different phenomena may cause
red shift.

3. Jul 7, 2010

### Ich

And pendulum clocks tick at different rates in different g-fields, and quartz clocks in different temperatures. That's not the point.
The point is: if you have controlled experimental conditions (same B/E field, same gravitational acceleration, same temperature and everything the same to sufficient accuracy), and you still get different rates, then that's time dilation. Time dilation is different from broken clocks in that it independent of local physical circumstances, and affects all clocks exactly the same way.

4. Jul 7, 2010

### cragar

good point , but clocks would tick at different rates in different B fields because they have energy , and this energy would cause space to bend .

5. Jul 7, 2010

### Ich

You sure that's what you wanted to say? Clocks have energy, bend space, and thus tick at different rates in different B fields? Doesn't make much sense.

6. Jul 7, 2010

### cragar

the B field has energy is what i meant to say , i worded it poorly .

7. Jul 7, 2010

### Ich

Ok. Energy curves spacetime, therefore time dilation.
But, I repeat, the important point is: It doesn't make a difference whether or not there is a B-field at the location of the clocks. You could have EM fields some 1000 km away and still have time dilation.

So all this does not imply that clocks tick at different rates in different B fields.

8. Jul 7, 2010

### cragar

but the B field will create a gravitational field , and we will at least have gravitational time dilation. And i thought i understood the pound-rebka experiment but from what you said above , why does the test verify gravitational time-dilation .

9. Jul 8, 2010

### Ich

Yes.
I don't know what you want to ask here. The experiment was intended to measure gravitational redshift. Redshift between static observers is equivalent to time dilation. Time dilation has nothing to do with clock malfunction due to magnetic fields.

10. Jul 8, 2010

### Staff: Mentor

I'd expect that the gravitational effects of the magnetic field used in a Zeeman effect setup are much weaker than the earth's gravitational field, which the Pound-Rebka experiment uses. Try calculating the energy stored in, say, a 1-tesla field that occupies a volume of 1 m^3, and compare it to the energy equivalent of the earth's mass.

11. Jul 8, 2010

### cragar

ok i understand that time-dilation has nothing to do with B fields now , magnetic fields would have to interact with photons for that to happen and they do not , Thanks for you responses .

12. Jul 8, 2010

### Ich

That's irrelevant. Example:
Code (Text):

BBBB
BBBB    1 ------- 2
BBBB

See the fat B-field to the left? It is responsible for time dilation (redshift) between clocks 1 and 2. The '-' depict photons going between 1 and 2.
There is no B-field at 1,2, or -. Therefore it is irrelevant how B-fields interact with 1,2, or -.
And it doesn't matter if there's a B-field to the left or any other form of mass or energy in suitable amounts. The effect is the same.

13. Jul 8, 2010

### cragar

even if a B field would cause a photon to be red-shifted , and red-shifted from the magnetic interaction , which does not happen obviously , there would be no time dilation.