Re: Science faces 'dangerous times'
- From: alan@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx (Alan)
- Date: Mon, 5 Dec 2005 18:48 +0000 (GMT Standard Time)
In article <1133801204.812377.5320@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
geraldkelleher@xxxxxxxxx (oriel36) wrote:
> It was only a matter of time before your breed showed up in
> geology,after all there is nothing left to destroy in astronomy so
> where else would you go.
http://www.spacedaily.com/news/gravity-05q.html
Einstein's Relativity Theory Proven With The 'Lead' Of A Pencil
Manchester, UK (SPX) Nov 10, 2005
Scientists at The University of Manchester have discovered a new way to test
Einstein's theory of relativity using the 'lead' of a pencil.
Until now it was only possible to test the theory by building expensive
machinery or by studying stars in distant galaxies, but a team of British,
Russian and Dutch scientists has now proven it can be done in the lab using an
ultra-thin material called Graphene.
The group, led by Professor Andre Geim of the School of Physics and Astronomy,
discovered the one atom thick material last year. Graphene is created by
extracting one atom thick slivers of graphite via a process similar to that of
tracing with a pencil.
Professor Geim, said: "To understand implications of the relativity theory,
researchers often have to go considerable lengths, but our work shows that it is
possible to set up direct experiments to test relativistic ideas. In theory,
this will speed up possible discoveries and probably save billions of pounds now
that tests can be set up using Graphene and relatively inexpensive laboratory
equipment."
In a paper published in Nature (November 10, 2005), the team describes how
electric charges in Graphene appear to behave like relativistic particles with
no mass (zero rest mass). The new particles are called massless Dirac fermions
and are described by Einstein's relativity theory (so-called the Dirac
equation).
The team also reports several new relativistic effects. They have shown that
massless Dirac fermions are pulled by magnetic fields in such a manner that they
gain a dynamic (motion) mass described by the famous Einstein's equation E=mc2.
This is similar to the case of photons (particles of light) that also have no
mass but can still feel the gravitational pull of the Sun due their dynamic mass
described by the same equation.
Dr Kostya Novoselov, a key investigator in this research, added: "The integer
and fractional quantum Hall effects are two of the most remarkable discoveries
of the late 20th century. It is not easy to explain their significance but both
discoveries led to Nobel prizes. One can probably appreciate the importance of
our present work in terms of fundamental physics, if I mention that one of the
phenomena we report is a new, relativistic type of the quantum Hall effect."
http://www.spacedaily.com/news/gravity-05p.html
Gravity Probe-B Data Collection Ends: Was Einstein Correct?
by Bob Kahn
Stanford CA (SPX) Oct 13, 2005
Almost 90 years after Einstein postulated his general theory of relativity?our
current theory of gravity?scientists have finally finished collecting the data
that will put this theory to an experimental test.
For the past 17 months, NASA's Gravity Probe-B (GP-B) satellite has been
orbiting the Earth using four ultra-precise gyroscopes, about a million times
better than the finest navigational gyroscopes, to generate the data required
for this unprecedented test.
As planned, the helium that cooled the experiment and powered its
micro-thrusters has run out, ending the data-collection and final instrument
calibration phase of the experiment.
All the data?50 weeks' worth?has been downloaded from the spacecraft and relayed
to computers in the GP-B Mission Operations Center at Stanford University, where
GP-B scientists have begun the final painstaking task of data analysis and
validation.
Was Einstein correct? They won't know for another 15 months, when the analysis
has been completed, but physicists around the world are eagerly awaiting the
results.
"This has been a tremendous mission for all of us," said Stanford's Francis
Everitt, GP-B's principal investigator. "Gravity Probe B presented many
challenges along the way and the team rose magnificently to every occasion. With
all the data now gathered, we are now proceeding very deliberately over the next
15 months to make sure that everything is checked and re-checked in as many ways
as possible. NASA and Stanford can be proud of what has been achieved so far."
This year, physicists celebrate the 100th anniversary of Einstein's "miraculous
year," in which he received his doctorate in physics from the University of
Zurich and published four seminal papers, including the special theory of
relativity and a paper on light that garnered him the Nobel Prize in 1921.
But Einstein's crowning achievement came in 1916, with his publication of the
general theory of relativity, in which he expanded the special theory of
relativity to include the elusive concept of gravity.
With general relativity, Einstein forever changed our Newtonian view of gravity
as a force, postulating rather that space and time are inextricably woven into a
four-dimensional fabric called spacetime, and that gravity is simply the warping
and twisting of the fabric of spacetime by massive celestial bodies.
Even though it has become one of the cornerstones of modern physics, general
relativity has remained the least tested of Einstein's theories. The reason is,
as Caltech physicist Kip Thorne once put it: "In the realm of black holes and
the universe, the language of general relativity is spoken, and it is spoken
loudly. But in our tiny solar system, the effects of general relativity are but
whispers."
And so, any measurements of the relativistic effects of gravity around Earth
must be carried out with utmost precision. Over the past 90 years, various tests
of the theory suggest that Einstein was on the right track. But, in most
previous tests, the relativity signals had to be extracted from a significant
level of background noise. The purpose of GP-B is to test Einstein's theory by
carrying out the experiment in a pristine orbiting laboratory, thereby reducing
background noise to insignificant levels and enabling the probe to examine
general relativity in new ways.
Deceptively simple
Launched on April 20, 2004, from Vandenberg Air Force Base on the California
coast, GP-B has been using four spherical gyroscopes to measure precisely two
extraordinary effects predicted by Einstein's theory. One is the geodetic
effect?the amount by which the Earth warps the local spacetime in which it
resides. The other effect, called frame-dragging, is the amount by which the
rotating Earth drags local spacetime around with it.
How does GP-B measure these effects? Conceptually, the experiment is simple:
Place a gyroscope and a telescope in a satellite orbiting the Earth. (GP-B uses
four gyroscopes for redundancy.) At the start of the experiment, align both the
telescope and the spin axis of the gyroscope with a distant reference point?a
guide star.
Keep the telescope aligned with the guide star for a year as the spacecraft
orbits the Earth more than 5,000 times. According to Einstein's theory, over the
course of a year, the geodetic warping of Earth's local spacetime should cause
the spin axis of the gyroscope to drift away from its initial guide star
alignment by a minuscule angle of 6.6 arcseconds (0.0018 degrees).
Likewise, the twisting of Earth's local spacetime should cause the spin axis to
drift in a perpendicular direction by an even smaller angle of 0.041 arcseconds
(0.000011 degrees), about the width of a human hair viewed from 10 miles away.
As the late Stanford physicist and GP-B co-founder William Fairbank once put it:
"No mission could be simpler than Gravity Probe B. It's just a star, a telescope
and a spinning sphere." However, it took the exceptional collaboration of
Stanford, NASA, Lockheed Martin and a host of other physicists, engineers and
space scientists almost 44 years to develop the ultra-precise gyroscopes and the
other cutting-edge technology necessary to carry out this deceptively "simple"
experiment.
The ping-pong-ball-sized gyroscope rotors, for example, had to be so perfectly
spherical and homogeneous that it took more than 10 years and a whole new set of
manufacturing techniques to produce them. They're now listed in the Guinness
Database of Records as the world's roundest objects. Similarly, it took two
years to make the flawless roof prisms in the GP-B science telescope that tracks
the guide star. Some scientists have mused about how Einstein, himself once a
patent clerk, would have enjoyed reviewing these extraordinary technologies.
Stanford's Bradford Parkinson, GP-B's co-principal investigator and winner of
the 2003 Draper Prize in Engineering, said: "Optimism was rampant [in 1960, when
GP-B began]. We didn't have any idea how hard this was, and I would contend it
was probably not until 30 years later that we brought [into existence] the
technology to make perfect spheres, the coating technology, the readout
technology, the cryogenic technology, the [telescope] pointing technology. A?
None of this was possible in 1960."
Running on empty
At launch, the Dewar, a giant Thermos bottle that comprises most of the body of
the spacecraft, contained approximately 650 gallons of helium, cooled to a
superfluid state just above absolute zero. The helium in the Dewar served two
vital functions: First, it was the superfluid bath that kept the four gyroscopes
at a superconductive temperature, required for the readout of their spin axes.
Second, helium gas that constantly evaporated from the bath was reused as the
propellant for the spacecraft's micro-thrusters to maintain both its proper
orientation and roll rate in orbit and to keep it pointed at the guide star.
When designing the Dewar, the team carefully calculated that 650 gallons of
helium would be adequate to sustain the GP-B mission for at least 16 months, and
that a Dewar large enough to hold that amount would just barely fit in the nose
of the Boeing Delta II rocket that would launch the experiment. When the helium
in the Dewar was depleted on Sept. 29, it had outlived the team's initial
calculations by more than three weeks.
Mac Keiser, GP-B chief scientist who heads the data analysis team at Stanford,
said: "Getting 50 weeks of data from the satellite has been particularly
important?not only because it will allow us to reduce our statistical errors but
also because the Earth has made almost a complete revolution around the sun.
This complete cycle will allow us to take full advantage of one of our
calibrating signals and eliminate potential sources of systematic error."
Next-to-last milestone
The completion of data collection marks the last milestone prior to announcing
and publishing the results of this historic 44-year program. It is a time of
both triumph and emotion for the GP-B team. Some team members have been working
together on the program for more than 15 years.
As the focus of the mission shifts from spacecraft operations to data analysis,
it is time for many of the team's engineers and mission operations specialists
to move on, and this naturally brings a note of sadness into the otherwise
joyful spirit of accomplishment.
"It's a bit like sending your kid off to college," said GP-B Program Manager
Gaylord Green. "Our operations team became a family accomplishing this mission,
and after a good job the members will be departing to the next phase of their
lives."
Added Tony Lyons, NASA's GP-B program manager from Marshall Space Flight Center
in Huntsville, Ala.: "The completion of the GP-B mission is the culmination of
years of hard work, training and preparation by the GP-B team. Every team member
should feel proud of this accomplishment."
It will take the GP-B science team more than a year to complete the data
analysis, followed by up to six months of preparing and submitting papers to
major scientific journals detailing the experimental results. Following NASA
protocols used for other missions with precise quantitative measurements, there
will be no preliminary announcements of results nor any speculation about the
data before a formal announcement and publication of results, expected early in
2007.
Bob Kahn is the public affairs coordinator for Gravity Probe B at Stanford.
Alan
http://www.veloceraptor.free-online.co.uk/enigma.html
http://veloceraptor.blogspot.com/
.
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