Light may arise from tiny relativity violations, according to a new
theory. Speaking most recently at last month's American Physical
Society meeting of the Division of Atomic, Molecular, and Optical
Physics in Nebraska, Alan Kostelecky of Indiana University (812
855-1485, KOSTELEC@INDIANA.EDU) described how light might exist as a
result of breaking an assumption of relativity theory known as
Lorentz symmetry. In Lorentz symmetry, the laws of physics stay the
same even when you change the orientation of a physical system (such
as a barbell-shaped molecule) or alter its velocity.
special relativity, the speed of light is the same in every
direction, a notion that current experiments verify to a few parts
in 10^16. However, if physicists find variations in the speed of
light with direction, this would provide evidence for broken Lorentz
symmetry, which would radically revise notions of the universe.
Broken Lorentz symmetry would give spacetime a preferred direction.
In its simplest form, broken Lorentz symmetry could be visualized as
a field of vectors (arrows) existing everywhere in the universe.
In such a picture, objects might behave slightly differently depending
upon their orientation with respect to the vectors. In a recent paper,
published in Physical Review D (Bluhm and Kostelecky, Physical Review
D, 71, 065008, published 22 March 2005; text at www.aip.org/physnews/select),
the authors propose that the very existence of light is made possible
through a vector field arising from broken Lorentz symmetry. In this
picture, light is a shimmering of the vector field analogous to a wave
blowing through a field of grain (see animation at http://www.physics.indiana.edu/~kostelec/faq.html).
have shown that this picture would hold in empty space as well as in
the presence of gravity (curved spacetime) which is often ignored in
conventional theories of light. This theory is in contrast to the
conventional view of light, which arises in a space without a
preferred direction and as a result of underlying symmetries in
particles and force fields. Kostelecky says that the new theory can
be tested by looking for minute changes in the way light interacts
with matter as the earth rotates (and changes its orientation with
respect to the putative vector field).
In addition, Kostelecky says
that neutrino oscillations might arise from interactions between
neutrinos and the background vector field, as opposed to the
conventional explanation, which invokes neutrino mass as the
explanation for the oscillations. Experimentalist Ron Walsworth of
Harvard-Smithsonian comments that the nice thing about Kostelecky's
work is that he proposes detailed experiments to test his theories;
and that the results of such experiments, no matter how they turn
out, promise to deepen our understanding of physics. (For more
information, see article by Kostelecky in the Scientific American,
September 2004; as well as Indiana University Press Release, March