Theory of Relativity was unequivocal -- the fastest objects in the universe
could move was the speed of light in a vacuum, which works out to
around 299,792,458 meters per second (approximately 7e8 miles an hour).
To travel faster than the speed of light would allow fast travel to other
worlds and even the possibility of travelling back in time. But
Einstein's 1905 theory was firm -- objects cannot travel faster than the speed
I. The Erosion of Relativity?
Over the last several decades, exceptions to the Theory of Relativity have
cropped up in experiments. For example physicists have discovered that
photons can pass through certain mediums at a faster than light pace via quantum tunneling, and another study
revealed pulses of sound can also outpace
photons in a medium.
Now, for the first time, subatomic particles have been witnessed as travelling
faster than the speed of light. CERN, the European physics
organization known for maintaining the Large
Hadron Collider, has been playing with neutrinos in its OPERA experiment. As they don't
interact with normal particles it's been sending them through the Earth, hurtling
from CERN in Geneva, Switzerland to INFN Gran Sasso Laboratory in Italy. The
journey is 454-miles (730-kilometers) long.
But the CERN researchers noticed something intriguing. The neutrino
traversed the distance 60±10 nanoseconds faster than light would have according
to advanced analysis using GPS systems and atomic clocks to measure the time it
took the roughly 15,000 neutrinos produced to complete their journey.
Those results indicate that the neutrinos were travelling
two-parts-per-million faster than the speed of light.
CERN has published the results [press release] and
presented a live webcast late last week on the discovery.
Robert Plunkett of the Fermilab laboratory in Batavia, Ill.
in an interview with LiveScience states,
"The consequences [of faster than light travel] would be absolutely
revolutionary and very profound. That's why such a claim should be treated very
carefully and validated as many ways as you can."
"According to relativity, it takes an infinite amount of energy to make
anything go faster than light. If these things are going faster than light,
then these rules would have to be rewritten."
Michael Peskin, a theoretical physicist
at SLAC National Accelerator Laboratory in Menlo Park,
Calif., concurs, adding, "It's really thought to be an absolute speed
limit. Quantum field theory, the mathematical theory on which basically all
results in particle physics are based, has the property that signals cannot
travel faster than the speed of light through a vacuum. It’s really an absolute
II. Physics Gets More Complicated
Absolute prohibition? Maybe not. The rules of physics seem on the
verge of getting a bit weirder. After all, to the best knowledge of most
physics professionals, the CERN results look accurate. But they seem in
direct contradiction to the Japanese Kamiokande II experiment, which measured
neutrinos emitted from a Large Magellanic Cloud supernova SN1987A, which sits
168,000 light years from Earth. Measurements from that exploded star
indicate that neutrinos travel within 1 part per 100,000,000 of the speed of
That's drastically different than the new results -- 2,000 times different, to
be precise. But both results could prove correct. Derek Fox of Pennsylvania State University suggests that a quirk of string theory or other advanced
physics theory could reconcile the measurements.
CERN isn't shying away from criticism. It is publishing all its data in
hopes that other theoretical physicists will help to verify it -- or disprove
the stunning conclusion.
One indication the results may be correct, though, comes from Fermilab, a
physics lab located just outside Batavia, Illinois. In its MINOS experiment, Femilab researchers have been sending
neutrinos in a similar experiment to a detector at the bottom of the Soudan
mine in Minnesota.
In 2007 they also seemed to observe faster-than-light travel of neutrinos, but
unfortunately their lesser experimental equipment made it impossible to
determine whether the measurement was legitimate or merely an artifact of the
high level of statistical deviation in the measurements.
Professor Plunkett, who also serves as co-spokesperson for the MINOS
experiment, is excited to find out if the results were authentic. He
states, "There was something that could have been a fluctuation in the
direction of things arriving early, but it didn't have enough significance for
us to make such a claim. Obviously, the hunt is on and we'll be upgrading that
previous measurement and also implementing something we already had in the
works, which is a plan to make improvements so we can reduce our errors. One of
our next objectives is going to be trying to verify or disprove this result as
hard as we can."
III. Just How Weird is Physics?
One thing that's important to bear in mind is that while this appears to be
macroscopic and substantial violation of the Theory of Relativity, it only applies
in a special scenario. By and large most objects in the universe still
appear to be behaving as expected.
In other words, basic physics education is unlikely to change much or get much
harder based on all these radical discoveries. However, for graduate
researchers in the field of physics, they better prepare themselves to deal
with a lot more weird.
The possibility of harnessing faster than light travel would seemingly be
wealth worth the headache, though. Many researchers are already dreaming up
faster than light spaceship engines. With such engines the vast time it would
take to travel to the stars could be drastically reduced.
Some quick background for the physics layperson, a neutrino is somewhat akin to
an uncharged electron, though it can come in several flavors -- electron
neutrinos, muon neutrinos and tau neutrinos. Neutrinos are typically
produced in nuclear reactions (including those inside stars) and when
high-energy cosmic rays collide with matter.
Neutrinos are hardly rare -- 6.5e10 (65 billion) pass through every square
centimeter perpendicular to the direction of the Sun in the region of the Earth
each second, courtesy of solar
generation. For that reason, researchers typically emit their
neutrinos in a direction roughly perpendicular to the solar neutrons, so they
can be easily distinguished and rely on careful calibration to filter out
remaining inaccuracies in the detector.
Like other particles, as per the Symmetry Theory, neutrinos have an
antiparticle, known as antineutrinos. However, some believe that
antineutrinos and neutrinos are actually the same particle type
(it's hard to determine as they lack distinguishing charge). If this is
true, it would make neutrinos/antineutrinos the only known (fermion) example of a
"Majorna" particle -- a particle that is it's own antiparticle.
If neutrinos and antineutrinos are not identical, it should be interesting
going ahead to see if antineutrinos -- produced from nuclear decay and fission,
among other things -- can also travel faster than light. One might expect
this to be the case, given that they only interact with matter gravitationally
and through the weak force, as with neutrinos.