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  • LIGO Hanford Observatory News
    so has another large optic As the photographs below reveal there is high drama in this work In Figure 1 at left the trial installation later repeated finally of the Mode Matching Telescope 3 mirror is a gripping sight Clad in clean room bunny suits our crew sweating in white the author Doug Cook and Dennis Coyne is intent on sliding the suspension and optic into place on the gleaming optics table in the HAM7 Horizontal Access Module chamber The cylinders visible near the assembly are counterweights placed to control the loading on the spring borne optics table as the payload is increased Next in Figure 2 is MIT s own David Shoemaker highlighted elsewhere in this issue David is carefully adjusting an orientation magnet on the recycling mirror newly placed in HAM9 Another milestone in glass In a somewhat different vein Figure 3 at right shows the large seismic isolation downtube being placed through the roof of the clean room into BSC8 Beam Splitter Chamber This chamber is the first of its type to receive the isolation system Next month after installation of the springs and leg elements this chamber will become the home of the folding mirror and

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/9902news/9902han.html (2015-06-02)
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  • LIGO Livingston Observatory News
    will continue in its state of rest or uniform motion unless acted on by an outside force which is the crucial concept of inertia which dates back to John Buridan in the Middle Ages One can recast this qualitative outline in more mathematical terms The equations of motion and the definition of momentum comes from the formalism can be obtained by Hamilton s principle Hamilton s principle requires the difference between the kinetic energy and the potential energy averaged over a period of time be minimized or in rare cases possibly maximized The averaged difference is called the action In detail Hamilton s principle requires in an abstract calculus known as calculus of variations that the first derivative of the action be zero Setting this derivative to zero gives the equations of motion F m a in the Newtonian case Recall that Newtonian physics with no forces is obtained when one has no potential energy so one is extremizing the kinetic energy only i e T V 1 2 m v 2 Note that the underlying Euclidean space is hidden in what mathematical entities are defined and how for example the dot product between two velocity vectors which gives the square of the magnitude of velocity v 2 implicitly utilizes the Euclidean space metric In Hamilton s formalism the conservation of linear momentum results from the action having translational symmetry i e not changing mathematical form when changing origin Now we are ready to address the two major issues in general relativity First in general relativity one does not in general have translational symmetry as discussed above because the underlying space is curved in an unrestrained fashion Second gravity takes on a different status in general relativity it is no longer treated like any other force The notion of inertial frames is completely reassessed The change in status of the gravitational field implies that momentum associated with the gravitational field must be treated differently from that of other fields To see how this comes about we must understand inertial frames more completely This takes us back to Newtonian physics In Newtonian physics one introduces the concept of global inertial frames in which time flows uniformly independent of space Given one inertial frame one can transfer to another frame by moving at a uniform speed with respect to the first frame and the laws of physics will remain unchanged Newton s way of looking at mechanics is obviously consistent and powerful but it contains an oddity associated with the concept of mass When an object is pulled by the gravity of a planet or any other object the mass that enters the equation for the planet s pull on the object the object s gravitational mass and the object s resistance to pull its inertial mass are exactly the same this is the weak equivalence principle In simple terms it means that given a certain experimental accuracy a man in free fall will see an inertial frame with that accuracy as

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/9902news/9902liv.html (2015-06-02)
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  • LIGO Caltech News
    7000 miles on that journey and my adventures included buying a recut tire somewhere near Mobile Alabama after one of the fronts came right off the rim on a very busy freeway If you drive across the USA once only I strongly recommend the middle route through the eroded sandstone plateau of Arizona Utah and New Mexico I am surprised when from time to time I meet Americans who have not visited that extraordinary part of the world After 1976 my attention was distracted by Uri Geller and I did a study on the scientists who were studying spoon bending children We ourselves did a participatory experiment putting the children in a psychology lab with a one way mirror There were dummy cameras and dummy observers in the lab and real cameras and real observers behind the mirror Most of our kids cheated and the experiment became quite famous for a while I thought the experiment pretty trivial and inconclusive and I was astonished by the amount of publicity it received merely because it told everyone what they wanted to hear I made a few enemies by pointing out how badly the exercise had been conducted immense pressure on the kids in the lab the numbers far too small to be generalisable and so forth Our lab became for a while the place in Britain to test spoon benders On the other hand I was quite pleased with a couple of simple innovations before each run we coated the bowls of the spoons in lamp black from a candle to detect if a stray thumb had used illegitimate force We also kept a flickering candle always in frame so that if anything interesting did happen no one could claim we had edited the film The theory was that while it would be easy to reset a clock in a film and most experimenters put clocks in their films it would be impossible to reset something uncontrollable like a candle flame We never found any convincing evidence of paranormal phenomena but we did discover a lot about human psychology as well as the sociology of science As a side note I have to mention that the most untrustworthy people I met during the course of that study were the stage magicians who made themselves the allies of orthodoxy they were always ready to bend the truth for the sake of science We never found however any stage magician willing to try to break our laboratory protocol For example James Randi would not do it though he visited our lab several times After that I became interested in expert systems I could not believe the early hype on this subject because I was certain that human knowledge could not be encapsulated in a set of rules I eventually built an expert system for telling people how to grow experimental semi conductor crystals having been apprenticed in the art by our physics lab technician I used this experience to explore the limits of

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/9902news/9902cit.html (2015-06-02)
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  • LIGO MIT News
    will be repeated with mind crushing constancy Eventually the newsletter will become a fully independent self perpetuating hands off automaton endlessly reiterating itself At last this will free up some slack time and allow me to sneak down to the Super Sub Post Sub Basement Annex where the boys from Bio Hazard wage their 24 hour 7day poker fest Deuces wild So slip on your bifocals settle back in your swivel chair and get ready to participate in our very first Best of LIGO MIT column Because a tale this good deserves to be repeated again And again And again Dr David Shoemaker The Compleat Physicist Contributed by David Shoemaker with a foreword by Syd Meshkov David Shoemaker is a Senior Research Scientist at the Center for Space Research at MIT He is additionally the Deputy Detector Group Leader for LIGO Recently it was suggested to David that we would enjoy publishing a biographical article about him and we asked for some helpful comments and data His reply a short first person narrative is an engaging story that we couldn t hope to improve upon It is presented in full after the following introductory paragraph Born in Boulder Colorado in 1953 David has also lived in Falls Church Virginia the comically named Walla Walla Washington Eugene Oregon Scotch Plains New Jersey Boston Massachusetts Munich Germany Paris France and now once again resides in Boston The photo at left is a recent snapshot of David in a characteristically good humored temper David Shoemaker Personal Notes My father was an experimental psychologist which used to mean mice mazes lights and trap doors and it was he who gave me my desire to understand how things fit together as well as come apart I was often in trouble when the typewriter clock or sewing machine was discovered dismantled into a hundred tiny pieces My education took a meandering path since playing guitar in rock bands seemed more important to me than schooling So it was a jazz bassist at Tufts University who was also secondarily in my opinion a Physics professor who convinced me to write an undergraduate thesis on the physics of the guitar This clicked as I discovered that a carefully guided intuition for experiment is as necessary as analysis to a successful measurement As I was finishing my undergraduate work at Tufts Prof Rainer Weiss of the Massachusetts Institute of Technology was searching for someone to help manage a teaching lab for Juniors at MIT and he engaged me as a technical assistant I was immediately drawn to Rai s approach to physics and became his graduate student in 1977 finishing my Masters Degree at MIT in 1980 My thesis was the construction and test of the far infrared spectrometer prototype for the Cosmic Background Explorer satellite and which made the definitive measurement of the Planck Spectrum of the Big Bang microwave background Afterwards when I stopped to weigh all things considered I had to admit that I didn t

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/9902news/9902mit.html (2015-06-02)
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  • LIGO Hanford Observatory News
    to support tubes that hold it at the correct height inside the vacuum chamber This entire assembly is a carefully designed ultrahigh vacuum component Atomic vibrations can start the downtube vibrating at its resonant frequencies so it has been designed to be as stiff as possible This means building it stiff and light like an airplane Although it looks solid it is actually built like an egg crate hollow with lots of cross bracing on the inside Then Figure 2 at right shows assembly of the vibration isolation stacks on top of the support structure which is now locked in place in the large BSC chamber The worker standing on the scaffolding is preparing the constrained layer damped coil springs used to absorb vibrations of the ground A mass element sitting on a layer of these springs is clearly visible When the ground shakes at frequencies above the resonances of these mass spring layers a few Hz the springs take up the shaking allowing the masses to float relatively freely The small amount of shaking that does get through one layer is further reduced by the springs in the next layer The springs have special shock absorbing material and structures inside the coils themselves to damp the resonant frequencies of the stack Next Figure 3 at left below shows the completed stacks The cabling which looks like brownish straps carries control signals for mirrors and optics that will be mounted on the optical table This cabling needs to be carefully designed not only for electrical and vacuum quality but also for its mechanical properties so it does not allow vibrations to end run around the stacks Then Figure 4 at right shows the view through the bottom of the BSC chamber The optical table floats at the top of the

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/9904news/9904han.html (2015-06-02)
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  • LIGO Livingston Observatory News
    Geophysics and Planetary Physics and by the Los Alamos National Laboratory at 40 geomagnetic latitude At present there are three operating magnetic stations in this chain San Gabriel CA Los Alamos NM and Livingston LA See the map in Figure 2 at right The LIGO site was chosen as the venue for this magnetometer because it provides both Internet access and a location away from traffic The magnetometer is a sensitive metal detector if the metal object is in motion Therefore the magnetometer requires a radius of exclusion from bicycles cars trucks trains etc and the larger the vehicle the larger the radius of exclusion necessary The heavily trafficked SLU campus was thus unsuitable for the instrument Installation of the magnetometer occurred in January this year Special thanks are due to several members of the LIGO staff Mark Coles provided his support and supervision Gerry Stapfer helped to determine where to situate the magnetometer which had to be buried underground where to place the personal computer that operates the magnetometer and that had to housed inside and how to run cables to connect these two Allen Sibley provided the exact coordinates of the magnetometer and answered various other questions Finally Tom Evans helped with the Internet connection Operations began on January 22 1999 Data from the first 30 days of operations already show many of the phenomena to be studied The data are shown in three graphs Figures 3 4 and 5 below of the X magnetic northward Y magnetic eastward and Z downward components of the magnetic field superimposed according to local time i e CST starting at local dawn 06 00 The data are displayed in this way since many atmospheric and magnetospheric phenomena occur in a fixed location relative to the sun The four vertical lines therefore separate the data into four sectors in a coordinate system fixed with respect to the sun these are referred to as morning afternoon premidnight and postmidnight The average magnetic field measured by the magnetometer is 18160 nT horizontally and 33630 nT vertically downward 181 6 mG 336 3 mG The average Y of 200 nT indicates a misalignment of the X axis from magnetic north of 0 63 A value less than 1 is considered acceptable Most of the traces follow a characteristic diurnal variation referred to as the quiet day variation which shows the effects of the solar driven ionospheric dynamo current system See Figure 6 at right The ionospheric dynamo is driven by solar heating and the shape of the dynamo represents a balance of thermal pressure Coriolis Lorentz and tidal forces on the ionosphere The ionospheric dynamo drives two current cells that are eastward at the equator and westward at higher latitudes In northern hemisphere winter the focus of the upper cell passes south of Livingston therefore the overhead current is southwesterly in the morning sector westerly at noon and northwesterly in the afternoon sector The ionospheric current produces a magnetic perturbation that is rotated 90 to

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/9904news/9904liv.html (2015-06-02)
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  • LIGO Caltech News
    and pictures used LIGO LISA Caltech Archives Joseph Taylor Louisiana State University Most who have seen these posters have agreed that they are magnificent spectacular impressive well done insert any superlative of your choice Viewing the Posters These three posters can be viewed in Adobe Acrobat Reader R by clicking on the respective links below Gravitational Waves Ripples in Spacetime PDF 623KB Astrophysical Sources of Gravitational Radiation PDF 430KB Gravitational Wave Detectors PDF 664KB Adobe Acrobat Reader R can be downloaded for free by clicking here Patrick Brady and Jolien Creighton also provided a video with cartoons showing the inspiralling binary neutron stars and an audio track of the gravitational wave signal Table Top Interferometer Fred Raab provided a working table top model of a Michelson interferometer using an inexpensive laser pointer as a source yes one set of triple A batteries provided power through all three days that proved invaluable for attracting people to the exhibit and providing a nifty hands on mechanism for explaining LIGO and other interferometer based detectors We had an enormous number of visitors a continuous stream to the exhibit over the three days These included a number of members of the Topical Group on Gravitation including Kip Thorne Bob Wald Rai Weiss and Barry Barish The most notable recognized visitor was the Nobel Prize winner himself Russell Hulse We also had the opportunity to talk to a number of high school students and teachers One additional factoid over 8 700 oral and poster presentations were given during the six day meeting By the end of my three day stint the voice was gone Night of the Stars Contributed by Gary Sanders Now LIGO is a science project That much is perfectly clear So it was with a bit of a surprise that I learned that LIGO had been selected for an engineering award The award carries the inscription Distinguished Engineering and Science Project Achievement of the Year Award 1999 and is bestowed by the Engineers Council of Woodland Hills California After collecting my thoughts I reminded myself that engineering is always done for a reason and science is as good a reason as any other And when it comes down to it LIGO truly is an impressive engineering achievement Perhaps it even is distinguished Our industrial partner Parsons Infrastructure and Technology of Pasadena felt that LIGO stood out as an engineering effort They nominated LIGO for this award and were seated in the audience at the presentation to join in the celebration It is the Parsons team that took our requirements and designed those great buildings and concrete slabs for the arms that we have been writing about all these months They managed the construction contractors who poured the concrete and assembled the framing and laid the plumbing and wiring in and all of the other activities that provided the conventional construction house for our laboratory and interferometers And when it was all completed they thought the whole project with its vacuum system and

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/9904news/9904cit.html (2015-06-02)
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  • LIGO MIT News
    The main business of the technical development groups was to develop a plan for the first upgrade of the LIGO detectors The steps outlined in the LSC White Paper October 1998 are still considered the baseline plan A design summit will be held by the development group on isolation systems and suspensions in May 1999 to establish an implementation plan and a schedule The plan will form the basis for

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/9904news/9904mit.html (2015-06-02)
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