Einstein's Theory 'Improved'? (Forwarded)
Andrew Yee
University of St Andrews
Fife, U.K.
Contact:
Gayle Cook, Press Officer
01334 467227 / 462529
13 Feb 2006
Einstein's Theory 'Improved'?
Research from the University of St Andrews has revealed that a 'simple'
fine-tuning in Einstein's theory of gravity could solve a dark mystery in
galaxies that has baffled astrophysicists for three- quarters of a
century.
By refining the law of gravity, Chinese astronomer Dr HongSheng Zhao and
his Belgian collaborator Dr Benoit Famaey of the Free University of
Brussels (ULB), aim to improve Einstein's theory and prove whether the
mysterious Dark Matter actually exists in galaxies.
Theories of the physics of gravity were first developed by Isaac Newton in
1687 and refined by Albert Einstein's general theory of relativity in 1905
so that the speed of gravity is equal to the speed of light. While it is
the earliest-known force, gravity is still very much a mystery with
theories still unconfirmed by astronomical observations in space.
The 'problem' with the golden laws of Newton and Einstein is that they do
not explain the accelerations of stars in galaxies where there is more
gravity observed than predicted.
Legend has it that Newton began thinking about gravity when an apple fell
on his head, but according to Dr Zhao: "It is not obvious how an apple
would fall in a galaxy. Mr Newton's theory would be off by a large margin;
his apple would fly out of the galaxy."
Astronomers believe that these stars move so fast they would fly apart if
they were not being held together by the gravitational attraction of a
huge amount of unseen material, first noted by Fritz Zwicky in 1933 and
now commonly referred to as Dark Matter (or DM).
Though astronomers cannot detect Dark Matter directly because it emits no
light or radiation, it is thought to account for up to 90% of the
Universe. Not all scientists believe in the DM theory however, with some
preferring to believe the theory proposed by Moti Milgrom in 1983 (and
backed up by Jacob Bekenstein in 2004) that a boost in the gravity of
ordinary matter is the cause of this acceleration.
Dr Zhao, a lecturer at the School of Physics and Astronomy at St Andrews
and member of the Scottish Universities Physics Alliance (SUPA),
continued: "Efforts to restore the apple on a nice orbit around the galaxy
has over the years led to two schools of thoughts: Dark Matter versus
non-Newtonian gravity. There has always been a fair chance that
astronomers might rewrite the law of gravity. We have tested a new formula
for gravity, which allows gravity to be boosted gradually from the
Einstein/Newtonian prediction further away from the solar system.
"Our 'simple formula', which is actually a refinement of Bekenstein's, is
consistent with galaxy data so far, and if further verified for solar
system and cosmology, it could solve the Dark Matter mystery. We may be
able to answer common questions such as whether Einstein's theory of
gravity is right and whether the so-called Dark Matter actually exists in
galaxies.
"A non-Newtonian gravity formula is now fully specified on all scales by a
smooth continuous function; it is ready for fellow scientists to falsify.
It is time to keep an open mind while we continue our search for Dark
Matter."
The new formula will be presented to an international audience of experts
at Edinburgh's Royal Observatory in April, which will be given the
opportunity to test and debate the reworked theory. Drs Zhao and Famaey
will demonstrate their new formula to an audience of Dark Matter and
gravity experts from ten different countries.
Dr Famaey commented: "It is possible that neither the modified gravity
theory, nor the DM theory, as they are formulated today, will solve all
the problems of galactic dynamics or cosmology.
"The truth could in principle lie in between, but it is very plausible
that we are missing something fundamental about gravity, and that a
radically new theoretical approach will be needed to solve all these
problems.
"Nevertheless, our formula is so attractively simple that it is tempting
to see it as part of a yet unknown fundamental theory. All galaxy data
seem to be explained effortlessly."
The results are published in the US-based Astrophysical Journal Letters.
ENDS
NOTE TO EDITORS:
THE RESEARCHERS ARE AVAILABLE FOR INTERVIEW:
UK HongSheng Zhao, University of St Andrews
01334 463135
Belgium - Benoit Famaey , Université Libre de Bruxelles (ULB)
+32-2-6502833
Dr Zhao is a PPARC (Particle Physics and Astronomy Research Council)
Advanced Fellow. For further info contact: Julia Maddock, Tel 01793 442094
Dr. Zhao also holds a NSF Overseas Outstanding Young Scholarship from
National Astronomical Observatory of China (contact Dr. B. Qin at Beijing
Observatory, qinbo @ bao.ac.cn)
The paper is available on line at:
http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2006ApJ...638L...9Z
IMAGE CAPTION:
[http://calvin.st-andrews.ac.uk/external_relations/down_loads/gravity%5Fhongsheng1%5Fsmall%2Ejpg
(8KB)]
HongSheng Zhao and the 'simple formula'. CREDIT: Tim Fitzpatrick.