Saturday is Sexy… Sunday is Movies Night
Hello, dear readers.
This is part three (3) of the Gravity & Magnetism Qs & As series. Let us jump right in.
Q: Within the last few years, physicists proved the existence of a particle that governs gravity, called a graviton. My question is this; are or could gravitons be affected by magnetism, and would supermassive magnets (like planets or stars) affecting clouds of gravitons by way of magnetic attraction be how gravity exists as we know it? And if this is all theoretically possible, what would the ramifications be for science (such as giving a possibly viable unified field theory?)
Sean Brown (age 24) Salt Lake City, UT, United States of America
A: The existence of the graviton is almost certain on theoretical grounds, but there is no experimental evidence for its existence. Nothing much has happened recently to change that. [Now in 2014, there is a change. The BICEP2 experiment has observed large-scale polarization fluctuations in the cosmic microwave background. These are believed to come from quantum mechanical fluctuations in gravitational waves, amplified by inflation. If that is confirmed, it’s experimental evidence of gravitons.]
Meanwhile, the energy in magnetic fields, like the energy in any other sort of field, is a source of gravity. (Remember that energy and mass are just two words for the same thing.) However, there is no special connection between magnetism and gravity.
Since absolutely nothing in physics itself suggests a special connection between magnetism and gravity, it’s interesting to speculate about why so many people have the impression that there must be such a connection. I guess it’s because these are the two forces which we often notice acting between objects that aren’t in contact. Static electricity does as well, as you can see by charging up balloons on strings etc, but I guess that isn’t as familiar.
Mike W. (published on 04/04/10)
Q: With virtual particles that are spin one bosons causing warping of extremely small chunks of spacetime with their mass or effective mass, it would seem like their is a connection between the energy density of a magnetic field and gravity. Is part of the issue that there is a symmetry breaking that keeps these two long range forces from being synonymous? I know we have an electroweak model, but why not an Electrogravitational model as einstein proposed? Due to the orders of magnitude difference in their strength (not referring to Higgs and range). Why are they so different in energy?
A: This is very much the same question that has also come in in more classical form.
The forces are both long-range because their carriers (photons and gravitons) have no rest-mass.
The next stage of force unification will presumably unify the electroweak and strong forces as remnants of a more symmetrical fundamental law, just as electromagnetism and the weak force were unified.
Including gravity in the unification is trickier because the quantum mechanics of spin-two massless particles leads to all sorts of infinities in a standard treatment. String theory is an attempt to construct a consistent quantum theory that includes gravity, but it requires an extra six spatial dimensions.
The question about the enormous range of strengths of the different forces is profound. It’s an active area of research, part of the whole unification issue, but over my head.
Mike W. (published on 04/07/10)
Source: University of Illinois
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