Dave
2015-11-28 03:44:57 UTC
http://www.americanthinker.com/articles/2015/11/einstein_your_gps_and_me.html
Einstein, Your GPS (and Me)
November 27, 2015
By S. Fred Singer
Just 100 years ago, Einstein announced his General Theory of
Relativity. Four decades later, I used it to calculate the
rate of a clock orbiting the Earth. It has turned out to be
of importance for the GPS system, which depends on accurate
clocks in navigation satellites.
Einstein and the General Theory of Relativity (GR)
In a Wall Street Journal op-ed (Without Albert Einstein, We
d All Be Lost), Robbert Dijkgraaf (director of Princetons
Institute for Advanced Study) reminds us that on Nov. 4,
1915, Albert Einstein, working alone in wartime [World
War-I, 1914-18] Berlin, submitted the first of four
scientific papers that would change the course of physics
and our view of the Cosmos: His general theory of
relativity (GR) is perhaps the greatest achievement of a
single human mind. Although it made Einstein the most
famous scientist in history, he did not live to see the full
impact of his ideas. He did not foresee earth satellites,
lunar landings, or the application of GR to GPS, the Global
Positioning System of navigation satellites.
As Dijkgraaf writes:
"Only now, a century later, are we gathering
apples from the tree he planted: black holes
that tear stars apart & ; cosmic gravitational
lenses that distort images of faraway galaxies,
as if seen through a funhouse mirror. And
perhaps the biggest wonder of all: a
comprehensive and detailed understanding of
the evolution of the universe. Amazingly, in just
100 years, humankind has uncovered 13.8
billion years of cosmic history.
"Only after Einstein's death in 1955 did his
theory become an active and respected
scientific field. Fifty years ago the first
physical evidence of the "big bang" was
observed. The past decade has brought a
new cascade of discoveries. The most
important is that we now know precisely what
we don't know. Einstein's theory allows us to
measure the weight of the universe and thereby
its energy content. This has been a shocker.
"All known forms of matter and energy--that is,
all the particles and radiation that make up us,
the Earth, the sun, all planets, stars and
intergalactic clouds--comprise just 4% of the
grand total. The remaining 96% is made of
unknown forms of "dark matter" and an even
more mysterious "dark energy," which
permeates all of space and drives the universe
to expand faster and faster. These days there
is a lot of talk about the 1% of society, but from
a cosmic point of view, we are all part of just
4% of the Cosmos."
Dijkgraaf continues:
"Many of the effects Einstein predicted were
too small or too distant to observe in his
lifetime. We had to wait for new technologies
to magnify these minuscule effects. For
example, without the theory of relativity the
GPS devices that we all use every day to find
our way would not function. The effects of time
delays in the rapid communication with satellites
of a few billionths of a second, as predicted by
Einstein's theory, translate into a drift of GPS
positions of 7 miles a day. Without relativity we
would all be lost."
MIT science historian David Kaiser tells us in the New York
Times how:
"right-wing political opportunists in war-ravaged
Germany began to organize raucous anti-Einstein
rallies. Only an effete Jew, they argued, could
remove 'force' from modern physics; those of true
Aryan spirit, they went on, shared an intuitive
sense of 'force' from generations of working the
land. Soon after the Nazis seized power in 1933,
they banned the teaching of Einsteins work within
the Reich. Einstein settled in Princeton for the last
22 years of his life; the German relativity community
was decimated."
The US certainly gained from the influx of European refugee
scientists, like Einstein, Bethe, Fermi, or Teller. Just
think what might have happened if Germany had developed
nuclear weapons during World-War-II.
GR and Me
About sixty years ago, I was a physics professor at the
University of Maryland and got into a friendly argument with
my colleague James L. Anderson, who was then teaching
general relativity and has written a widely praised textbook
since. The question was: What will be the rate of a clock
orbiting the earth? Would it slow down, or would it speed
up? We finally settled the argument with a bet. I would
write up my conclusion and send it to the prestigious
Physical Review; if they published it, I would win my bet.
If they turned it down, I would concede defeat.
To pass my PhD exams, I had of course studied relativity as
a graduate student but had never used it. I actually met
the great Einstein just once; but we never talked about
relativity. I remember him as very kind and patient; he
asked me to describe my PhD thesis research.
My thesis advisor, Professor John Archibald Wheeler, was an
expert in GR; but my thesis topic dealt with cosmic-ray
particle- showers produced in the upper atmosphere by
extremely high-energy cosmic-ray primaries from outer space.
Of course, I made great use of the Special Theory of
Relativity published by Einstein in 1905 -- especially the
well-known formula E=mc2.
To solve the clock problem, I used a rather standard
approach called Schwarzschild equation, which is based on
Einsteins GR theory. All I really added to the problem was
a method of overcoming the inadequacy of atomic clocks at
the time. I suggested that by counting ticks and by using
a number of clocks in orbit instead of just one, one might
achieve the necessary accuracy. I have to confess that at
the time I did not regard my paper as a big deal; its
preparation was mainly in response to a bet. In retrospect,
however, I am glad I wrote up my calculations.
My published result was actually quite interesting. I found
that the clock rate would depend on the altitude of the
orbiting satellite. If the orbit altitude was one-half
earth radius (about 3200km), the clock rate will be the same
as on the earths surface. At a lower altitude, a clock
would run slower; at a higher altitude, it would run faster
than on the surface. In a separate publication, in Nature,
I addressed the famous twin paradox that claims that the
space-traveler twin would age less quickly than his
earth-bound brother.
There is still much unexplored territory for research in
relativity. I became interested in a topic that Einstein
called frame dragging (FD). Does the Earths rotation
affect the clock rate -- and to what extent? A prize awaits
the enterprising researcher; but the experimental
requirements, I have concluded, are too demanding. What a
pity.
The most ambitious attempt to-date to measure the FD effect
was Project Gravity-B, a satellite experiment by Stanford
physicists. The multi-billion dollar effort was a marvel of
technology but the hoped-for effect was too small to
surmount inherent noisiness of the measurement. In recent
weeks, the European Space Agency announced a plan to use
atomic clocks in their Galileo satellites for detecting FD.
However, I have great doubt about the success of their
project.
GPS and Me
In 1987, some 30 years later, I found myself in the
Department of Transportation and learned that the global
positioning system (GPS) made use of exactly the results
that I had published in the Physical Review. But by then
the whole matter had been re-discovered by the designers of
GPS. Still, it was a very satisfactory conclusion of a
small chapter in my research experience.
My main task as DOTs chief scientist was to look after the
FAAs revision of the Air Traffic Control system. An
additional responsibility was to keep track of and promote
civilian applications of the GPS -- then a new military
system. Making the Federal Aviation Administration aware of
the potential of GPS took a lot of effort; in fact,
conservative FAAers still harbor deep suspicions about
using satellites. But civilian GPS applications have grown
explosively since then; every day brings new applications
for this remarkable technology.
I still remember a meeting of our senior DOT staff with the
Secretary. I held up an early rather bulky GPS receiver and
announced: Just turn on this gadget when you wake up some
morning, and you dont know where you are or where you are
going. They all thought I was kidding.
S. Fred Singer is professor emeritus at the University of
Virginia and a founding director of the Science &
Environmental Policy Project; in 2014, after 25 years, he
stepped down as president of SEPP. His specialty is
atmospheric and space physics. An expert in remote sensing
and satellites, he served as the founding director of the US
Weather Satellite Service and, more recently, as vice chair
of the US National Advisory Committee on Oceans &
Atmosphere. He is an elected Fellow of several scientific
societies and a Senior Fellow of the Heartland Institute and
the Independent Institute. He co-authored the NY Times
best-seller Unstoppable Global Warming: Every 1500 years.
In 2007, he founded and has chaired the NIPCC
(Nongovernmental International Panel on Climate Change),
which has released several scientific reports [See
NIPCCreport.org]. For recent writings see
http://www.americanthinker.com/s_fred_singer/ and also
Google Scholar.
Einstein, Your GPS (and Me)
November 27, 2015
By S. Fred Singer
Just 100 years ago, Einstein announced his General Theory of
Relativity. Four decades later, I used it to calculate the
rate of a clock orbiting the Earth. It has turned out to be
of importance for the GPS system, which depends on accurate
clocks in navigation satellites.
Einstein and the General Theory of Relativity (GR)
In a Wall Street Journal op-ed (Without Albert Einstein, We
d All Be Lost), Robbert Dijkgraaf (director of Princetons
Institute for Advanced Study) reminds us that on Nov. 4,
1915, Albert Einstein, working alone in wartime [World
War-I, 1914-18] Berlin, submitted the first of four
scientific papers that would change the course of physics
and our view of the Cosmos: His general theory of
relativity (GR) is perhaps the greatest achievement of a
single human mind. Although it made Einstein the most
famous scientist in history, he did not live to see the full
impact of his ideas. He did not foresee earth satellites,
lunar landings, or the application of GR to GPS, the Global
Positioning System of navigation satellites.
As Dijkgraaf writes:
"Only now, a century later, are we gathering
apples from the tree he planted: black holes
that tear stars apart & ; cosmic gravitational
lenses that distort images of faraway galaxies,
as if seen through a funhouse mirror. And
perhaps the biggest wonder of all: a
comprehensive and detailed understanding of
the evolution of the universe. Amazingly, in just
100 years, humankind has uncovered 13.8
billion years of cosmic history.
"Only after Einstein's death in 1955 did his
theory become an active and respected
scientific field. Fifty years ago the first
physical evidence of the "big bang" was
observed. The past decade has brought a
new cascade of discoveries. The most
important is that we now know precisely what
we don't know. Einstein's theory allows us to
measure the weight of the universe and thereby
its energy content. This has been a shocker.
"All known forms of matter and energy--that is,
all the particles and radiation that make up us,
the Earth, the sun, all planets, stars and
intergalactic clouds--comprise just 4% of the
grand total. The remaining 96% is made of
unknown forms of "dark matter" and an even
more mysterious "dark energy," which
permeates all of space and drives the universe
to expand faster and faster. These days there
is a lot of talk about the 1% of society, but from
a cosmic point of view, we are all part of just
4% of the Cosmos."
Dijkgraaf continues:
"Many of the effects Einstein predicted were
too small or too distant to observe in his
lifetime. We had to wait for new technologies
to magnify these minuscule effects. For
example, without the theory of relativity the
GPS devices that we all use every day to find
our way would not function. The effects of time
delays in the rapid communication with satellites
of a few billionths of a second, as predicted by
Einstein's theory, translate into a drift of GPS
positions of 7 miles a day. Without relativity we
would all be lost."
MIT science historian David Kaiser tells us in the New York
Times how:
"right-wing political opportunists in war-ravaged
Germany began to organize raucous anti-Einstein
rallies. Only an effete Jew, they argued, could
remove 'force' from modern physics; those of true
Aryan spirit, they went on, shared an intuitive
sense of 'force' from generations of working the
land. Soon after the Nazis seized power in 1933,
they banned the teaching of Einsteins work within
the Reich. Einstein settled in Princeton for the last
22 years of his life; the German relativity community
was decimated."
The US certainly gained from the influx of European refugee
scientists, like Einstein, Bethe, Fermi, or Teller. Just
think what might have happened if Germany had developed
nuclear weapons during World-War-II.
GR and Me
About sixty years ago, I was a physics professor at the
University of Maryland and got into a friendly argument with
my colleague James L. Anderson, who was then teaching
general relativity and has written a widely praised textbook
since. The question was: What will be the rate of a clock
orbiting the earth? Would it slow down, or would it speed
up? We finally settled the argument with a bet. I would
write up my conclusion and send it to the prestigious
Physical Review; if they published it, I would win my bet.
If they turned it down, I would concede defeat.
To pass my PhD exams, I had of course studied relativity as
a graduate student but had never used it. I actually met
the great Einstein just once; but we never talked about
relativity. I remember him as very kind and patient; he
asked me to describe my PhD thesis research.
My thesis advisor, Professor John Archibald Wheeler, was an
expert in GR; but my thesis topic dealt with cosmic-ray
particle- showers produced in the upper atmosphere by
extremely high-energy cosmic-ray primaries from outer space.
Of course, I made great use of the Special Theory of
Relativity published by Einstein in 1905 -- especially the
well-known formula E=mc2.
To solve the clock problem, I used a rather standard
approach called Schwarzschild equation, which is based on
Einsteins GR theory. All I really added to the problem was
a method of overcoming the inadequacy of atomic clocks at
the time. I suggested that by counting ticks and by using
a number of clocks in orbit instead of just one, one might
achieve the necessary accuracy. I have to confess that at
the time I did not regard my paper as a big deal; its
preparation was mainly in response to a bet. In retrospect,
however, I am glad I wrote up my calculations.
My published result was actually quite interesting. I found
that the clock rate would depend on the altitude of the
orbiting satellite. If the orbit altitude was one-half
earth radius (about 3200km), the clock rate will be the same
as on the earths surface. At a lower altitude, a clock
would run slower; at a higher altitude, it would run faster
than on the surface. In a separate publication, in Nature,
I addressed the famous twin paradox that claims that the
space-traveler twin would age less quickly than his
earth-bound brother.
There is still much unexplored territory for research in
relativity. I became interested in a topic that Einstein
called frame dragging (FD). Does the Earths rotation
affect the clock rate -- and to what extent? A prize awaits
the enterprising researcher; but the experimental
requirements, I have concluded, are too demanding. What a
pity.
The most ambitious attempt to-date to measure the FD effect
was Project Gravity-B, a satellite experiment by Stanford
physicists. The multi-billion dollar effort was a marvel of
technology but the hoped-for effect was too small to
surmount inherent noisiness of the measurement. In recent
weeks, the European Space Agency announced a plan to use
atomic clocks in their Galileo satellites for detecting FD.
However, I have great doubt about the success of their
project.
GPS and Me
In 1987, some 30 years later, I found myself in the
Department of Transportation and learned that the global
positioning system (GPS) made use of exactly the results
that I had published in the Physical Review. But by then
the whole matter had been re-discovered by the designers of
GPS. Still, it was a very satisfactory conclusion of a
small chapter in my research experience.
My main task as DOTs chief scientist was to look after the
FAAs revision of the Air Traffic Control system. An
additional responsibility was to keep track of and promote
civilian applications of the GPS -- then a new military
system. Making the Federal Aviation Administration aware of
the potential of GPS took a lot of effort; in fact,
conservative FAAers still harbor deep suspicions about
using satellites. But civilian GPS applications have grown
explosively since then; every day brings new applications
for this remarkable technology.
I still remember a meeting of our senior DOT staff with the
Secretary. I held up an early rather bulky GPS receiver and
announced: Just turn on this gadget when you wake up some
morning, and you dont know where you are or where you are
going. They all thought I was kidding.
S. Fred Singer is professor emeritus at the University of
Virginia and a founding director of the Science &
Environmental Policy Project; in 2014, after 25 years, he
stepped down as president of SEPP. His specialty is
atmospheric and space physics. An expert in remote sensing
and satellites, he served as the founding director of the US
Weather Satellite Service and, more recently, as vice chair
of the US National Advisory Committee on Oceans &
Atmosphere. He is an elected Fellow of several scientific
societies and a Senior Fellow of the Heartland Institute and
the Independent Institute. He co-authored the NY Times
best-seller Unstoppable Global Warming: Every 1500 years.
In 2007, he founded and has chaired the NIPCC
(Nongovernmental International Panel on Climate Change),
which has released several scientific reports [See
NIPCCreport.org]. For recent writings see
http://www.americanthinker.com/s_fred_singer/ and also
Google Scholar.