My
September 26 newsletter discussed a recent experiment at the Italian
“OPERA” neutrino detector. Physicists there claimed to have observed
neutrinos traveling faster than light speed, arriving 61 billionths of
a second before Einstein said was possible.
While there are many possible technical problems with the measurement,
an October 17th paper by Dutch physicist Ronald van Elburg raises a
more profound issue. I thank my dear friend Dr. Jerry Clifford for
referring me to this insightful paper.
Elburg says the analysis was simply done in the wrong reference frame,
and if done properly, the experiment proves Einstein was right, once
again.
Einstein said space and time are relative, meaning there is no single
right answer to “how long is this distance?” or “how much time did that
take?” These answers depend on the observer, and in particular on how
fast the observer is moving relative to what is being measured. If two
observers moving at different speeds measure the speed of a photon, a
particle of light, they will measure different values for the path
length traveled by the photon and different values for its transit
time. But when each observer computes the photon’s speed they’ll get
the same result — the speed of light. If one observer measures the path
length being 10% more then he will necessarily measure the transit time
also being 10% more, thus measuring the same speed (speed = distance /
time).
Clearly this doesn’t work if we divide one observer’s distance by a
different observer’s time, which is what Elburg said the OPERA
physicists inadvertently did.
The clocks measuring neutrino arrival times at OPERA (80 miles from
Rome) and the clocks used to infer neutrino departure times at CERN
(near Geneva) were all synchronized to clocks on GPS satellites. Thus
the time measurements were really being made in the satellite reference
frame, the frame in which the satellites are stationary and Earth is
moving. To be consistent, the CERN-to-OPERA distance must also be
measured in the satellite frame. (The GPS satellites are 12,000 miles
above Earth and moving more than 8400 miles per hour.)
As seen in the satellites’ frame, Elburg states, while the neutrinos
move toward OPERA at almost the speed of light, the OPERA detector
moves toward CERN at 8400 mph. This reduces their effective path length
so they arrive earlier than the physicists expected. The distance
traveled looks shorter in the GPS frame than it looks to observers on
Earth. Elburg estimates this effect could reduce the neutrinos’ transit
time by 64 billionths of a second, making the experimental result
consistent with Einstein’s theory that nothing travels faster than
light.
The exact value of Elburg’s correction depends on precisely where the
GPS satellites are during the neutrino transit and how the
synchronization is accomplished. Only the physicists at OPERA have
access to these details. It’s now up to them to apply Elburg’s
equations to precisely determine the correction.
My money’s still on Einstein.
Best Regards,
Robert
November 9, 2011
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Never too young or
too old
to wonder: Why?
Dr Robert
Piccioni,
Author of "Everyone's
Guide to Atoms, Einstein, and the Universe"
and " Can Life Be
Merely An Accident?"
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