[CraigD]

Originally Posted by Little Bang

Is there any proof that light is totally unaffected by a magnetic field?

Yes.

Rather, we should say, there’s no credible experimental data showing a magnetic field having any affect on light, with the exception of light of high enough frequency to be subject to pair production.

It’s easy to confirm this with equipment available to nearly anyone, such as a strong permanent magnet and a laser pointer. It’s very easy to confirmed via many textbooks and science education outreach websites, such as this one.

Though much of modern physics requires equipment not available to most people, this is not such a case. Rather than speculating about light being affected by magnetic fields, but the affect either being overlooked, ignored, or suppressed, any of us can design and conduct simple experiments to reveal the effect, if it exists.

[Little Bang]

I would hardly consider a laser beam on a wall and a magnet as a test. I would consider the moon laser and a magnetic field as test.

[Little Bang]

Sorry Will I didn't put the site for you see in post 160.

Electric Gravity in an Electric Universe

[Erasmus00]

Originally Posted by Little Bang

Rather interesting don't you think Will.

Electric Gravity in an Electric Universe

A few problems I can think of- if gravity is caused by electric dipoles in objects, there should be measurable electric dipoles all over the place, and there aren't.

The claim that all nucleons have aligned magnetic dipoles is demonstrably false- if this were the case NMR would be much better than it is. As it stands, experimentalists go to great lengths to get their samples very cold so that the spins do begin to align.

Also, gravity does not need to be instantaneous for the solar system to be stable- in fact some of the decaying orbits of binary stars that we have observed require gravity to have a finite propagation speed.

The idea that neutrinos have electric dipoles is also broken, they'd move about in electric fields.
-Will

[CraigD]

Originally Posted by Little Bang

I would hardly consider a laser beam on a wall and a magnet as a test. I would consider the moon laser and a magnetic field as test.

Why would you not consider the beam of an inexpensive laser passed throught the magnetic field of an inexpensive permanent magnet a test of the effect on a magnetic field on light?

Lasers emit light. Permanent magnets produce magnetic fields. If light is deflected by a magnetic field, it would be possible to detect it by the change in position of the visible dot made by the laser on a screen.

The powerful lasers used in Lunar Laser Ranging Experiments differ from the inexpensive lasers used as pointers (and cat toys ) only is the quantity of photons they produce (the reflection of an ordinary laser pointer, from a lunar retroreflector is much too faint – too few photons per unit time – to be detected against the light noise of the many frequencies of photons in moonlight) and the precision with which they can be switched on and off (typical human reaction time in pressing and releasing a button – about 0.1 seconds – would allow ranging of the moon to a precision of only about , while the very short switching time of lasers like the MLRS’s - about 0.000000003 to 0.0000000002 seconds – combined with a lot of statistical averaging, give a precision of about 0.03 m.

Permanent magnets are very strong (around 1 T for a good-quality rare earth one), compared to magnetic fields found around the bodies found in our solar system (a sunspot has about 0.15 T, the Earth a max of around 0.00,005 T, the solar system on average around 0.00,000,000,001 T). So, except for exotic objects like neutron stars (1,000,000 to 100,000,000,000 T), The deflection of a particle with charge and momentum by a magnetic field of strength over a length is

. So even though the of outer-space magnetic fields are much larger than ones made with permanent magnets, their much lower means that they don’t result in much larger deflections () of charged particles. Intuitively, the of electrons in a small CRT monitor is not much different than that of a solar wind electron by the Earth’s magnetosphere.

(Sources: wikipedia article “Orders of magnitude (magnetic flux density)”; Magnetic Deflection of Electrons)

[Little Bang]

A laser propagates at C and you expect a magnet to deflect it over short distances. Like I said why not pick a test vehicle that has a chance such as the moon laser. Are you afraid of what they might discover?

[Erasmus00]

Originally Posted by Little Bang

A laser propagates at C and you expect a magnet to deflect it over short distances. Like I said why not pick a test vehicle that has a chance such as the moon laser. Are you afraid of what they might discover?

The Earth has a magnetic field of its own, which would already effect the lasers aimed at the moon if magnetic fields could defect light.
-Will

[Moontanman]

Originally Posted by Little Bang

A laser propagates at C and you expect a magnet to deflect it over short distances. Like I said why not pick a test vehicle that has a chance such as the moon laser. Are you afraid of what they might discover?

Lasers are routinely bounced off the moon via reflectors that were placed there by the astronauts. No magnetic effects have been reported.

[Little Bang]

I guess your right Will. Why run a cheap test only to verify what you already know. There is no sense in running a test that would destroy the elegant standard model.

[freeztar]

Originally Posted by Little Bang

I guess your right Will. Why run a cheap test only to verify what you already know. There is no sense in running a test that would destroy the elegant standard model.

I think you misunderstood. Every time they fire the laser at the moon and retrieve the photons bounced back, it is an experiment. If the Earth's magnetic field influenced the path of the photons, then the reciever would not detect their return and people would have known long ago that something was awry.