Hi, thank you for bringing your question to Google Answers.
Can light be bent by electromagnetic (EM) fields? The short answer is
no, ?but? with an explanation.
EM fields bend the path of moving particles such as in the Solar Wind,
or simply in a TV tube which uses EM fields to deflect (bend) electron
Since light is both a wave and a particle at the same time, you might
think that this would cause light to be bent if only you had a strong
After all, light is bent by gravity, so what?s the difference?
The reason EM fields can bend the path of many particles is because
those particles are carrying an electrical charge ? the EM field is
actually affecting the charge associated with the particle.
Photons (light) have spin (1) but do not have an electrical charge so
they aren?t affected by even very strong magnetic fields.
One simple demonstration I?ve heard, and which makes complete sense,
is that since radio and TV transmitters produce very powerful EM
fields at the antenna, if light were bent by an EM field you would
expect there to be some visual blurring, but there is none which isn?t
accounted for by heat on hot days.
That, of course, isn?t proof in any real sense, but it does agree with
all the major accepted theoretical explanations so it makes practical
Now for the ?but? in the explanation.
At the quantum level, an effect known as Delbruck scattering can occur
where it is thought that an extremely powerful EM wave can break a
photon down into an electron and a positron, both of which do carry a
charge and can therefore have their paths altered by an EM field.
This effect is extremely difficult to observe and probably too small
to measure given the nature of such things and the Heisenberg
Uncertainty Principal, but there can be a scattering effect where the
particle and anti-particle annihilate each other and form two
lower-energy photons which then travel in different directions.
Technically in most instances this would produce a splitting rather
than a bending, but it does describe one way that EM fields can
interact with a light beam even though the photon technically is not a
photon during the only time interaction can occur (between the
splitting into electron and positron and the rejoining - i.e.
annihilation.) The field only effects the electron and positron.
And, here is a good lay explanation of light bending by gravity:
There is an excellent description of light, including an animation of
an EM field, at
Maxwell?s equations, which I can?t reproduce here due to graphics
limitations, are the governing laws for any electromagnetic field
(including light) at anything larger than quantum dimensions, except
for gravitational effects which you must turn to Einstein for (don?t
blame Maxwell, as with many advances in science, Maxwell didn?t
address any gravitational effects, leaving that for Einstein.)
In fact, Maxwell?s field theory of EM stands up very well until you
get to very short distances where String Theory attempts to explain
things. Unfortunately, String Theory describes things so small that it
doesn?t appear to be possible to make any testable predictions based
on String Theory which is why many scientists reject that it is really
a ?theory? in the tradition of scientific method. You have to be able
to predict and test the predictions to have a valid "theory".
Magnetic Fields and Light
Google Search Term:
can an electromagnetic field bend light
Einstein?s 1911 paper, ?On the influence of gravitation on the
Propagation of Light,? and more technical information on bending light
beams is available at:
A quick intro to String Theory:
I hope this provided the answer you were seeking along with lots of
reference links to follow. The bottom line is that while gravity (on
the order of magnitude of that near a star?s surface) can be shown to
bend light, there has never been an experiment which demonstrated
bending a beam of light using any combination of EM fields and/or
There are some theories which may, if proven true, leave open some
possibility of bending light but there has never been any evidence of
this except for the side issue of scattering due to some rare quantum
effects I described, effects which are virtually too small to measure
in most instances.
While quantum mechanics says that photons are constantly splitting up
into positron and electron pairs, then quickly recombining, you can
affect the path of individual photons by scattering some, but this
isn?t something you can control to bend a stream of photons (beam of
EM still doesn't affect individual photons when they are photons and
you won?t be able shine a pointer LASER beam past an electromagnet of
any arbitrary strength and see it bend.
One reason we feel that we understand EM well enough to say it can?t
bend light is because taking EM theory as it now stands, it neatly
explains all of chemistry and biology as well as power generation, TV,
radio, and such.
Clarification of Answer by
09 Jan 2006 04:52 PST
Join scientists (GRIN), who are often confused ? Einstein, for
example, never really came to grips with quantum mechanics.
If your question regards kottekoe?s comments, please address your
questions to that individual, I?m not at all clear what parts of that
comment means myself, especially when it talks about polarizing a
vacuum or that ?Thus, light can be bent.?
Although people are free to add comments, I think those particular
comments only serve to confuse you.
The light particle (remember that light sometimes acts like a wave and
sometimes like a particle) can?t be affected by any electromagnetic
field, or an electron which has an electrical charge.
In wave form light also can?t be affected.
The extremely rare and tiny variations I described only occur because
the photon turns into something else. As I explained in detail, what
happens at the quantum mechanical level is that the photon actually
breaks up into an electron and a positron, both of which do carry an
electrical charge and can therefore be affected by a magnetic field.
Those ARE ?bent? or are at least affected by an EM field, but they
aren?t light (photons) during the extremely brief period when they are
interacting with the EM field, they are an electron and a positron
pair which usually recombine (although possibly not the same ones
since the EM field moves them in different directions) and become a
photon (light) again and, because they were diverted from their
original path by the EM field while they were charged particles, the
final photon (which isn?t actually identical with the original one
anyway) will probably be moving in a different path.
(My point about electrons not interacting with light doesn?t count the
quantum reaction where light quanta are absorbed and raise an electron
to a higher orbit or where an orbit decays and emits a photon ? that
has nothing to do with bending anything any more than using a piece of
black paper to block a light beam.)
I know this can be confusing (I used to have long discussions about
things such as QM and magnetic monopoles with a friend, Dr. Van Vleck,
who helped develop quantum mechanics and it really isn?t easy to
understand such abstract mathematical concepts in language even if you
are a relatively advanced physics student) but just bear in mind that,
under all currently accepted and seriously proposed theories, light
itself, which is made up of a stream of photons/an EM field, has no
charge and therefore can?t be directly affected by a magnetic field of
any sort while it is still light.
As for kottekoe?s statement, they may make sense in some context but
you really need to address a comment to that person to learn what they
are talking about since that would be a different question.
I hope that clears things up, if not, please follow some of the links
I provided for detailed explanations of various concepts raised by my
Thank you for bringing your question to Google Answers.