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Can a light be bent by a magnetic field?

Could gravitational lensing be the refraction of hydrogen, helium, gases and cosmic dust?

Refraction is the change in direction of propagation of a wave due to a change in its transmission medium.

“Medium” refers to an intervening substance, such as hydrogen atoms, through which a force acts or an effect is produced.

Refraction of light is a commonly observed phenomenon.

Space isn't empty. As the Earth makes its annual journey around the sun, it collects about 40,000 tons of dust.

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No, because we've seen it happen between galaxies, where there's not enough intergalactic material to account for this.

Here's an example: the galaxy cluster Abell 2744:

Then there's Einstein's cross:

You need something extremely massive to account for the lensing shown here. Gravitational lensing can accurately predict these images, and the deflection formula gives an accurate measure of the mass of the galaxy doing the bending.

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  • $\begingroup$ Magnetic fields can’t bend light. Particles that are influenced by a magnetic field do bend light. Faraday rotation a magneto-optical phenomenon is an interaction between light and a magnetic field in a medium. The medium refers to an intervening substance, solid or gas magnetized particle in space, through which a force acts or an effect is produced. Could magnetized particles cause Gravitational Lensing? $\endgroup$
    – Symmetry
    Commented Apr 3, 2015 at 19:55
  • $\begingroup$ @Symmetry I have no idea, but I highly doubt that this could happen on such a large scale. $\endgroup$
    – HDE 226868
    Commented Apr 3, 2015 at 20:24
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    $\begingroup$ @Symmetry The point is that space is pretty much entirely empty. There is nothing like a "medium" out there in space. $\endgroup$
    – Danu
    Commented Apr 3, 2015 at 22:24
  • $\begingroup$ @Danu Well, technically, no. Densities in some spots can be pretty high relative to "ordinary" space inside a galaxy. But for all intents and purposes (I think), yes, it's empty. $\endgroup$
    – HDE 226868
    Commented Apr 3, 2015 at 22:26
  • $\begingroup$ @HDE226868 Interesting point. However, note the word "sparse" in the first sentence of your link. Just like you already said, I don't think this is a significant effect. $\endgroup$
    – Danu
    Commented Apr 3, 2015 at 22:28
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Could gravitational lensing be the refraction of hydrogen, helium, gases and cosmic dust?

You can add up the total density required. You can then look for the spectroscopic effect that this density would imply. We don't see them.

So, no, it couldn't.

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  • $\begingroup$ I didn't say that. I said that refraction in the interstellar medium is not responsible. Of course nebulae gravitate, but that is not what you asked about. $\endgroup$
    – dmckee --- ex-moderator kitten
    Commented Apr 4, 2015 at 7:01
  • $\begingroup$ Does a Nebula align with a galactic magnetic field and cause the scattered light to be slightly polarized. $\endgroup$
    – Symmetry
    Commented Apr 8, 2015 at 2:33

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