Variations in fine-structure constant suggest laws of physics not the same everywhere

One of the most controversial questions in
cosmology is why the fundamental constants of nature seem fine-tuned
...for life. One of these fundamental constants is the fine-structure
constant, or alpha, which is the coupling constant for the
electromagnetic force and equal to about 1/137.0359. If alpha were just
4% bigger or smaller than it is, stars wouldn't be able to make carbon
and oxygen, which would have made it impossible for life as we know it
to exist. Now, results from a new study show that alpha seems to have
varied a tiny bit in different directions of the universe billions of
years ago, being slightly smaller in the northern hemisphere and
slightly larger in the southern hemisphere. One intriguing possible
implication is that the fine-structure constant is continuously varying
in space, and seems fine-tuned for life in our neighborhood of the
universe.

The physicists, John Webb from the University of New South
Wales and his coauthors, used data from two telescopes to uncover the
spatial dependence of the fine-structure constant. Using the
north-facing Keck telescope in Mauna Kea, Hawaii, and the south-facing
Very Large Telescope (VLT) in Paranal, Chile, the researchers observed
more than 100 quasars, which are extremely luminous and distant galaxies
that are powered by massive black holes at their centers.
By measuring the quasar spectra, the researchers could gather data on the frequency of the electromagnetic radiation
emitted by quasars at high redshifts, corresponding to a time about 10
billion years ago. During the time the light traveled through space to
reach the telescopes, some of it was absorbed at specific wavelengths by
very old gas clouds that today can reveal the chemical composition of the clouds.

The cloud compositions could help the scientists determine the
fine-structure constant in those areas of the universe at that time,
since alpha
is a measure of the strength of the electromagnetic force between
electrically charged particles. As the coupling constant for the
electromagnetic force, it is similar to the constants for the other
three known fundamental forces of nature: the strong nuclear force, the
weak nuclear force, and gravitational force. Among its important
implications, alpha determines how strongly atoms hold on to their
electrons.
By combining the data from the two telescopes that look in opposite
directions, the researchers found that, 10 billion years ago, alpha
seems to have been larger by about one part in 100,000 in the southern
direction and smaller by one part in 100,000 in the northern direction.
The data for this “dipole” model of alpha has a statistical significance
of about 4.1 sigma, meaning that that there is only a one in 15,000
chance that it is a random event. 

 

At first, the data surprised Webb and his colleagues, since it seemed
to contradict previous results that the scientists had published in
1999. At that time, the scientists had used the north-facing Keck
telescope to find that alpha became slightly smaller the further away
(and older) the quasars were. So when the scientists first looked at
equally distant quasars from the southern hemisphere
using the VLT, they were surprised to find the slight increase in
alpha. After eliminating any possible bias, though, they realized that
they were looking at hemispherical differences of alpha.
While the data from just one telescope seemed to suggest that alpha
varies in time, data from the two telescopes show that alpha also seems
to vary in space. Such a discovery could have major implications,
starting with shattering the basic assumption that physical laws are the
same everywhere in the universe. The results also violate the Einstein
Equivalence Principle, and suggest that the universe may be much larger
than currently thought - or even infinite in size. Right now, the
scientists want to confirm the results with other experimental methods,
and see if the fine-structure constant could truly lead scientists to a
very different understanding of our universe.