LIGO- Laser Interferometer Gravitational Wave Observatory
Gravitational Wave detection
Astrophysical Phenomenon
Theory of relativity
2017 Nobel prize in physics
3. INTRODUCTION
LIGO
3
First phenomenon in the world of physics that was
predicted exactly a hundred years prior to its
detection.
One of the most intelligent man’s life’s work.
A discovery which confirmed one the most mind
boggling, famous and seemingly impossible to
understand theories at the time of its making.
A new insight to see at our physical universe, a
new telescope that we point at the continuum of
spacetime.
4. LIGO
4
GRAVITATIONAL WAVES ARE 'RIPPLES' IN SPACE-TIME CAUSED BY SOME OF THE MOST
VIOLENT AND ENERGETIC PROCESSES IN THE UNIVERSE. GRAVITATIONAL WAVES
TRAVEL AT THE SPEED OF LIGHT (186,000 MILES PER SECOND). THESE WAVES
SQUEEZE AND STRETCH ANYTHING IN THEIR PATH AS THEY PASS BY. IT’S IMPORTANT
TO DETECT THEM BECAUSE GRAVITATIONAL WAVES CARRY INFORMATION ABOUT
THEIR INCEPTION AND ABOUT THE FUNDAMENTAL PROPERTIES OF GRAVITY THAT
CAN’T BE SEEN THROUGH OBSERVATIONS OF THE ELECTROMAGNETIC SPECTRUM.
THE STRONGEST GRAVITATIONAL WAVES ARE PRODUCED BY CATACLYSMIC EVENTS
SUCH AS COLLIDING BLACK HOLES, SUPERNOVAE (MASSIVE STARS EXPLODING AT THE
END OF THEIR LIFETIMES), AND COLLIDING NEUTRON STARS.
GRAVITATIONAL WAVES
5.
6. 1. THALES OF MILETUS (7TH AND 6TH CENTURIES BCE) IS CONSIDERED THE
FATHER OF SCIENCE. SCIENCE WAS BORN WHEN WE FIRST STRUCT TWO STONES
TO MAKE SHAPE EDGES AND MADE WEAPONS OUT OF STONES AND WOOD, LATER
OUR CURIOUS MINDS STARTED TO PONDER ABOUT THE REASON BEHIND THE
ATTRACTION BY MAGNETS AND RUBBED AMBER.
2. MY CIVILIZATIONS SUCH AS BABYLONIANS, GREEKS, INDIANS, EGYPTIANS,
CHINESE, MAYA, AND MANY ANCIENT INDIGENOUS PEOPLES OF THE AMERICAS
DID A BIT STUDY ABOUT THE ASTRONOMY.
3. AROUND THE SAME TIME GREEK, CHINESE AND INDIANS STARTED TO DEVELOP
THEIR TECHNOLOGIES AND RATIONAL THINKING AND STARTED STUDIES WHICH WE
CALL CHEMISTRY, BIOLOGY AND PHYSICS TODAY
LIGO
6
STARTING WITH OUR
STORY
7. 4. MESOPOTAMIA AND EGYPT – PLIMPTON 322 (BABYLONIAN C. 2000 – 1900 BC),
THE RHIND MATHEMATICAL PAPYRUS (EGYPTIAN C. 1800 BC) AND THE MOSCOW
MATHEMATICAL PAPYRUS (EGYPTIAN C. 1890 BC) AND MANY CIVILIZATIONS LIKE
INDIAN, GREEK, ROMANS, CHINESE AND ARABS STARTED THEIR WORK IN
MATHEMATICS FOR TRADE, ETC.
5. NICOLAUS COPERNICUS IS CONSIDERED FATHER OF MODERN ASTRONOMY.
6. GALILEO GALILEI IS CONSIDERED THE FATHER OF MODERN PHYSICS.
7. ARCHIMEDES IS CONSIDERED THE FATHER OF MATHEMATICS.
LIGO
7
STARTING WITH OUR
STORY
8. STORY
LIGO
8
1503, 1605
AND 1687
Nicolaus
Copernicus, Galileo
Galilei and Issac
Newton our ancient
founding fathers for
today’s concepts to
happen.
1905 AND
1915
Einstein proposing
his theories of
special and general
relativity which
changed our
understanding about
the Universe.
1893 AND
1905
First time someone,
i.e; Oliver Heaviside
and Henri Poincaré
proposing the
concept of
Gravitational waves.
1989
First time someone,
i.e; three scientists
proposing to build
LIGO and a start of
collaboration of
three firms to make
it an reality.
2015
First ever detection
of Gravitational
waves using LIGO
within the first few
hours of it being
operational.
9. NICOLAUS COPERNICUS
LIGO
9
COPERNICUS’S MAJOR WORK WAS HIS HELIOCENTRIC THEORY
WHICH HE MADE USING THREE OBSERVATIONS OF MERCURY, WITH
ERRORS OF −3, −15 AND −1 MINUTES OF ARC. HE MADE ONE OF
VENUS, WITH AN ERROR OF −24 MINUTES. FOUR WERE MADE OF
MARS, WITH ERRORS OF 2, 20, 77, AND 137 MINUTES. FOUR
OBSERVATIONS WERE MADE OF JUPITER, WITH ERRORS OF 32, 51,
−11 AND 25 MINUTES. HE MADE FOUR OF SATURN, WITH ERRORS OF
31, 20, 23 AND −4 MINUTES. THIS LEAD TO THE START OF COPERNICUS
REVOLUTION WHICH CHANGED THE WAY OUR UNIVERSE WAS VIEWED
AND STUDIED. THIS CHANGED THE DIRECTION OF ASTRONOMY.
10. GALILEO STUDIED SPEED AND VELOCITY, GRAVITY AND FREE FALL, THE
PRINCIPLE OF RELATIVITY, INERTIA, PROJECTILE MOTION AND ALSO WORKED
IN APPLIED SCIENCE AND TECHNOLOGY, DESCRIBING THE PROPERTIES OF
PENDULUMS AND "HYDROSTATIC BALANCES". HE INVENTED THE
THERMOSCOPE AND VARIOUS MILITARY COMPASSES, AND USED THE
TELESCOPE FOR SCIENTIFIC OBSERVATIONS OF CELESTIAL OBJECTS. HIS
CONTRIBUTIONS TO OBSERVATIONAL ASTRONOMY INCLUDE TELESCOPIC
CONFIRMATION OF THE PHASES OF VENUS, OBSERVATION OF THE FOUR
LARGEST SATELLITES OF JUPITER, OBSERVATION OF SATURN'S RINGS, AND
ANALYSIS OF LUNAR CRATERS AND SUNSPOTS.
GALILEO DI VINCENZO BONAIUTI DE' GALILEI
LIGO
1 0
11. THE LAWS OF MOTION ARE SAME IN ALL INERTIAL FRAMES OF REFERENCE.
GALILEO GALILEI FIRST DESCRIBED THIS PRINCIPLE IN 1632 IN HIS DIALOGUE
CONCERNING THE TWO CHIEF WORLD SYSTEMS USING THE EXAMPLE OF A SHIP
TRAVELLING AT CONSTANT VELOCITY, WITHOUT ROCKING, ON A SMOOTH SEA; ANY
OBSERVER BELOW THE DECK WOULD NOT BE ABLE TO TELL WHETHER THE SHIP
WAS MOVING OR STATIONARY. THE YOUNG ALBERT EINSTEIN "WAS ENGROSSED IN
ANALYZING GALILEO'S PRINCIPLE OF INERTIA (GALILEAN RELATIVITY)".
SPECIFICALLY, THE TERM GALILEAN INVARIANCE TODAY USUALLY REFERS TO THIS
PRINCIPLE AS APPLIED TO NEWTONIAN MECHANICS, THAT IS, NEWTON'S LAWS OF
MOTION HOLD IN ALL FRAMES RELATED TO ONE ANOTHER BY A
GALILEAN TRANSFORMATION.
GALILEO DI VINCENZO BONAIUTI DE' GALILEI
LIGO
11
12. AND UNIVERSAL GRAVITATION [THE GUY WHO DISCOVERED
GRAVITY] THAT FORMED THE DOMINANT SCIENTIFIC VIEWPOINT
FOR CENTURIES UNTIL IT WAS SUPERSEDED BY THE THEORY OF
RELATIVITY. NEWTON USED HIS MATHEMATICAL DESCRIPTION OF
GRAVITY TO DERIVE KEPLER'S LAWS OF PLANETARY MOTION,
ACCOUNT FOR TIDES, THE TRAJECTORIES OF COMETS, THE
PRECESSION OF THE EQUINOXES AND OTHER PHENOMENA,
ERADICATING DOUBT ABOUT THE SOLAR SYSTEM'S
HELIOCENTRICITY. HE DEMONSTRATED THAT THE MOTION OF
OBJECTS ON EARTH AND CELESTIAL BODIES COULD BE
ACCOUNTED FOR BY THE SAME PRINCIPLES.
SIR ISAAC NEWTON
1 2
LIGO
13. INVENTED A NEW TECHNIQUE FOR SOLVING DIFFERENTIAL
EQUATIONS (EQUIVALENT TO THE LAPLACE TRANSFORM),
INDEPENDENTLY DEVELOPED VECTOR CALCULUS, AND
REWROTE MAXWELL'S EQUATIONS IN THE FORM COMMONLY
USED TODAY. FORMED TELEGRAPHER'S EQUATION CHANGING
THE FIELD OF TELECOMMUNICATION FOREVER. HEAVISIDE
CHANGED THE FACE OF TELECOMMUNICATIONS,
MATHEMATICS, AND SCIENCE. HE WAS THE FIRST PERSON TO
DISCUSS ABOUT THE POSSIBILITY OF GRAVITATIONAL WAVES
USING THE ANALOGY BETWEEN THE INVERSE-SQUARE LAW
IN GRAVITATION AND ELECTRICITY.
OLIVER HEAVISIDE AND HENRI POINCARÉ
1 3
LIGO
14. OLIVER HEAVISIDE AND HENRI POINCARÉ
1 4
LIGO
ELECTRICITY, TELEGRAPHY, CAPILLARITY, ELASTICITY,
THERMODYNAMICS, POTENTIAL THEORY, QUANTUM
THEORY, THEORY OF RELATIVITY AND PHYSICAL
COSMOLOGY. IN 1905 POINCARÉ FIRST PROPOSED
GRAVITATIONAL WAVES (ONDES GRAVIFIQUES)
EMANATING FROM A BODY AND PROPAGATING AT THE
SPEED OF LIGHT. EINSTEIN RELIED ON THE PRINCIPLE OF
RELATIVITY PROPOSED BY POICORE TO DERIVE THE
LORENTZ TRANSFORMATIONS AND USED A SIMILAR
CLOCK SYNCHRONISATION PROCEDURE (EINSTEIN
SYNCHRONISATION) TO THE ONE THAT POINCARÉ
(1900) HAD DESCRIBED.
15. HE WAS THE ONE WHO LAID THE FUNDAMENTALS TO
MODERN ASTRONOMY AND SPACE SCIENCES
THROUGH HIS THEORIES OF SPECIAL AND GENERAL
RELATIVITY AND PREDICTED THE EXISTENCE AND
DETECTION OF GRAVITATIONAL WAVES RIPPLES IN
THE CURVATURE OF SPACETIME WHICH PROPAGATE
AS WAVES, TRAVELING OUTWARD FROM THE SOURCE,
TRANSPORTING ENERGY AS
GRAVITATIONAL RADIATION.
HANS ALBERT EINTEIN
1 5
LIGO
17. THORNE FOR DECISIVE CONTRIBUTIONS TO THE LIGO
DETECTOR AND THE OBSERVATION OF
GRAVITATIONAL WAVES. IN FEBRUARY 2016 WEISS,
BARISH, THORNE AND COLLEAGUES WORKING ON THE
LASER INTERFEROMETER GRAVITATIONAL-WAVE
OBSERVATORY (LIGO) IN THE US ANNOUNCED THAT THEY
HAD MADE THE FIRST DIRECT DETECTION OF
GRAVITATIONAL WAVES. THE OBSERVATION WAS MADE IN
SEPTEMBER 2015 AND THE GRAVITATIONAL WAVES HAD
BEEN CREATED BY THE MERGER OF TWO
DISTANT BLACK HOLES.
RAINER WEISS, KIP THORNE, AND BARRY
BARISH
1 7
LIGO
18. WEISS BROUGHT TWO
FIELDS OF FUNDAMENTAL
PHYSICS RESEARCH FROM
BIRTH TO MATURITY:
CHARACTERIZATION OF THE
COSMIC BACKGROUND
RADIATION, AND
INTERFEROMETRIC
GRAVITATIONAL
WAVE OBSERVATION.
RAINER WEISS, KIP THORNE, AND BARRY
BARISH
1 8
LIGO
GRAVITATION PHYSICS, WITH
EMPHASIS ON RELATIVISTIC
STARS, BLACK HOLES AND
ESPECIALLY GRAVITATIONAL
WAVES. HE IS PERHAPS BEST
KNOWN TO THE PUBLIC FOR HIS
CONTROVERSIAL THEORY THAT
WORMHOLES CAN CONCEIVABLY
BE USED FOR TIME TRAVEL.
HOWEVER, THORNE'S SCIENTIFIC
CONTRIBUTIONS, WHICH CENTER
ON THE GENERAL NATURE OF
SPACE, TIME, AND GRAVITY, SPAN
THE FULL RANGE OF TOPICS IN
GENERAL RELATIVITY.
QUARK SUBSTRUCTURE OF THE
NUCLEON. HE SEARCHED FOR
EXOTIC PARTICLES CALLED
MAGNETIC MONOPOLES AND
ALSO STUDIED PENETRATING
COSMIC RAYS, INCLUDING
NEUTRINO MEASUREMENTS THAT
PROVIDED IMPORTANT
CONFIRMATORY EVIDENCE THAT
NEUTRINOS HAVE MASS AND
OSCILLATE. BARISH BECAME THE
PRINCIPAL INVESTIGATOR OF THE
LASER INTERFEROMETER
GRAVITATIONAL-WAVE
OBSERVATORY (LIGO) IN 1994 AND
DIRECTOR IN 1997.
20. STUDENTS (ACCEPTANCE RATE OF 5.7%), IT IS ONE OF THE WORLD'S MOST SELECTIVE
UNIVERSITIES. AS OF OCTOBER 2022, THERE ARE 79 NOBEL LAUREATES WHO HAVE BEEN AFFILIATED
WITH CALTECH, MAKING IT THE INSTITUTION WITH THE HIGHEST NUMBER OF NOBELISTS PER
CAPITA IN AMERICA.
THE MASSACHUSETTS INSTITUTE OF TECHNOLOGY (MIT) IS A PRIVATE LAND-GRANT RESEARCH
UNIVERSITY IN CAMBRIDGE, MASSACHUSETTS. AS OF DECEMBER 2021, 98 NOBEL LAUREATES, 26
TURING AWARD WINNERS, AND 8 FIELDS MEDALISTS HAVE BEEN AFFILIATED WITH MIT AS ALUMNI,
FACULTY MEMBERS, OR RESEARCHERS.
THE NATIONAL SCIENCE FOUNDATION (NSF) IS AN INDEPENDENT AGENCY OF THE UNITED STATES
GOVERNMENT THAT SUPPORTS FUNDAMENTAL RESEARCH AND EDUCATION IN ALL THE NON-
MEDICAL FIELDS OF SCIENCE AND ENGINEERING. ITS MEDICAL COUNTERPART IS THE NATIONAL
INSTITUTES OF HEALTH. THE NSF'S DIRECTOR AND DEPUTY DIRECTOR ARE APPOINTED BY THE
PRESIDENT OF THE UNITED STATES AND CONFIRMED BY THE UNITED STATES SENATE, WHEREAS
THE 24 PRESIDENT-APPOINTED MEMBERS OF THE NATIONAL SCIENCE BOARD (NSB) DO NOT
REQUIRE SENATE CONFIRMATION.
CALTECH, MIT AND NATIONAL SCIENCE FOUNDATION
2 0
LIGO
21. LIGO STANDS FOR "LASER INTERFEROMETER GRAVITATIONAL-WAVE OBSERVATORY". AN
INSTRUMENT IN WHICH THE INTERFERENCE OF TWO BEAMS OF LIGHT IS EMPLOYED TO MAKE
PRECISE MEASUREMENTS. IT IS THE WORLD'S LARGEST GRAVITATIONAL WAVE OBSERVATORY AND A
MARVEL OF PRECISION ENGINEERING. DESIGNING INSTRUMENTS LIKE LIGO'S INTERFEROMETERS,
CAPABLE OF MEASURING A DISTANCE ON THE ORDER OF 10-19 METERS REQUIRED INVENTING AND
REFINING INNOVATIVE TECHNOLOGY. MOST OF LIGO’S MOST IMPRESSIVE TECHNOLOGY RESIDES IN
ITS SEISMIC ISOLATION SYSTEMS (WHICH REMOVE UNWANTED VIBRATIONS), VACUUM SYSTEMS (TO
MAKE SURE THE LASER LIGHT IS KEPT PURE), OPTICS COMPONENTS (TO PRESERVE LASER LIGHT
AND LASER POWER), AND COMPUTING INFRASTRUCTURE (TO HANDLE THE MINDBOGGLING AMOUNT
OF DATA THAT LIGO COLLECTS). THESE SYSTEMS ARE LIKE LIGO'S INTERNAL ORGANS. IF ANY ONE
FAILS, THE WHOLE INSTRUMENT SUFFERS.
LASER INTERFEROMETER GRAVITATIONAL WAVE OBSERVATORY
2 1
LIGO
22. INTERFEROMETERS LOCATED 3000 KILOMETERS
APART, LIGO EXPLOITS THE PHYSICAL PROPERTIES OF
LIGHT AND OF SPACE ITSELF TO DETECT AND
UNDERSTAND THE ORIGINS OF GRAVITATIONAL WAVES
(GW). EACH LIGO DETECTOR CONSISTS OF TWO ARMS,
EACH 4KM (2.5 MI.) LONG, COMPRISING 1.2M-WIDE
STEEL VACUUM TUBES ARRANGED IN AN "L" SHAPE,
AND COVERED BY A 10-FOOT WIDE, 12-FOOT TALL
CONCRETE SHELTER THAT PROTECTS THE TUBES
FROM THE ENVIRONMENT. LIGO CAN ALSO DETECT
GRAVITATIONAL WAVES COMING FROM ANY DIRECTION
(EVEN BELOW)! A SINGLE LIGO DETECTOR COULD NOT
INITIALLY CONFIRM GRAVITATIONAL WAVES ON ITS
OWN.
BASIC CONSTRUCTION AND WORKING
2 2
LIGO
23. THE CHANGE IN DISTANCE BETWEEN LIGO'S MIRRORS (TEST MASSES) WHEN A
GRAVITATIONAL WAVE PASSES IS ON THE ORDER OF 10-19 M. IT IS ALSO EXTREMELY
SENSITIVE TO ALL VIBRATIONS NEAR (SUCH AS TRUCKS DRIVING ON NEARBY ROADS),
FAR (EARTHQUAKES ON THE OTHER SIDE OF THE WORLD), WEATHER PATTERNS,
MOVEMENTS OF TECTONIC PLATES, ETC. WITHOUT TAKING EXTRAORDINARY
MEASURES, ANY NUMBER OF EARTHLY VIBRATIONS COULD MOVE LIGO’S PRIMARY
MIRRORS (LIGO SCIENTISTS CALL THEM “TEST MASSES”) ENOUGH TO HIDE A
GRAVITATIONAL WAVE SIGNAL. ISOLATING LIGO FROM AS MUCH ENVIRONMENTAL
VIBRATION AS POSSIBLE IS THE LINCHPIN IN LIGO’S QUEST TO FEEL GRAVITATIONAL
WAVES. TO THAT END, LIGO USES MULTIPLE MEANS OF ELIMINATING VIBRATION
FALLING INTO TWO BROAD CATEGORIES: “ACTIVE” AND “PASSIVE” DAMPING SYSTEMS.
SEISMIC ISOLATION
2 3
LIGO
24. COUNTER MOVEMENTS TO ELIMINATE THEM, KEEPING THE
INSTRUMENT MOTION-FREE. IN THESE SYSTEMS, INTERNAL
SEISMIC ISOLATION PLATFORMS (ISIS) UTILIZE POSITION- AND
VIBRATION-SENSORS (LIKE SEISMOMETERS) TUNED TO
DIFFERENT FREQUENCIES OF ENVIRONMENTAL VIBRATIONS,
ALONG WITH PERMANENT-MAGNET ACTUATORS. TOGETHER,
THESE FEEDBACK SYSTEMS COUNTERACT GROUND
MOVEMENTS, KEEPING THE INTERNAL COMPONENTS OF THE
INTERFEROMETER VIRTUALLY MOTION-FREE. THIS ACTIVE
LEVEL OF ISOLATION CAN REDUCE THE MAGNITUDE OF
VIBRATIONS INTRODUCED TO THE SUSPENSIONS (AT THE
POINT OF THEIR ATTACHMENT TO THE ISI) TO A LEVEL OF AT
MOST 2X10-13 M. THE FEEDBACK AND CONTROL SYSTEM THAT
KEEPS JUST LIGO’S ARMS IN PERFECT ALIGNMENT REPORTS
CHANGES 16,384 TIMES PER SECOND, OR 16 KILOHERTZ (KHZ)!
SEISMIC ISOLATION- ACTIVE DAMPING
2 4
LIGO
25. EFFECTIVELY, THE LENGTHS OF LIGO'S ARM CAVITIES (I.E., THE
DISTANCE BETWEEN THE TEST MASSES AT THE ENDS OF EACH
ARM) MUST NOT VARY BY MORE THAN A FRACTION OF A
PICOMETER (ONE-TRILLIONTH OF A METER). TO HOLD THE MASSES
STEADY AND IN PLACE, WE NEED TO PUSH ON THEM (EXTREMELY
CAREFULLY!) THIS IS THE ROLE OF THE REACTION CHAIN. THE
UPPER TWO MASSES ARE CONTROLLED BY SIMPLE MOTORS MADE
OF PERMANENT MAGNETS AND ELECTRICAL COILS THAT PUSH ON
THE MASSES. THESE 'VOICE COILS' WORK LIKE AUDIO
LOUDSPEAKERS, WITH THE COIL PRODUCING A MAGNETIC FIELD
WHICH ATTRACTS OR REPELS THE MAGNETS, WHICH IN TURN
GENTLY MOVES THE MASSES TO COUNTERACT VIBRATIONS. ON
THE TEST MASSES THEMSELVES, WE USE MORE GENTLE
ELECTROSTATIC FORCES, LIKE THOSE THAT ATTRACT BALLOONS
RUBBED ON A SWEATER TO A WALL (OR HAIR TO A COMB ON A DRY
DAY). THE GOAL IS TO KEEP THE MASSES PERFECTLY STILL
WITHOUT PHYSICALLY TOUCHING THEM.
SEISMIC ISOLATION- PASSIVE DAMPING
2 5
LIGO
26. MOLECULES.
TURBO-PUMP VACUUMS (LIKE LITTLE JET ENGINES THAT CREATE SUCTION INSTEAD OF THRUST)
SUCKED OUT THE BULK OF THE AIR CONTAINED IN THE TUBES.
ION PUMPS THEN EXTRACT INDIVIDUAL REMAINING GAS MOLECULES BY ELECTRICALLY CHARGING
THEM AND THEN ATTRACTING THEM AWAY WITH OPPOSITE CHARGE, LIKE A MAGNET. SINCE THE METAL
INSIDE THE VACUUM CHAMBER IS ALWAYS EMITTING SOME GASEOUS MOLECULES ("OUTGASSING"),
THESE PUMPS OPERATE CONTINUOUSLY IN ORDER TO MAINTAIN THE PRISTINE VACUUM INSIDE THE
TUBES.
STRAY WATER MOLECULES ARE ALSO REMOVED BY CONTINUOUSLY OPERATING LIQUID NITROGEN
CRYOPUMPS; THE WATER MOLECULES STICK TO THEM.
IT TOOK 40 DAYS (1100 HOURS) TO REMOVE ALL 10,000 M3 (353,000 FT3) OF AIR AND OTHER RESIDUAL
GASES FROM EACH OF LIGO’S VACUUM TUBES TO REACH AN AIR PRESSURE ONE-TRILLIONTH OF AN
ATMOSPHERE..
BEAM TUBE INSTALLATION- EARTH’S CURVATURE- THE 1.2 M DIAMETER BEAM TUBES WERE CREATED
IN 20-METER SEGMENTS. EACH ONE WAS MADE OF A CONTINUOUS RIBBON OF FLAT STEEL A MERE 3
MM THICK.
VACUUM
2 6
LIGO
27. FINGERNAIL-SIZED CRYSTAL OF MAN-MADE GARNET, WITHIN WHICH IT CIRCULATES
AND STIMULATES THE EMISSION OF A 2 WATT BEAM WITH A WAVELENGTH OF 1064
NANOMETERS (NM). THIS CRYSTAL LASING DEVICE IS CALLED A NON-PLANAR RING
OSCILLATOR (NPRO) AND THE RESULTING 2 W BEAM IS CALLED A “SEED” BEAM. THE
SEED BEAM PASSES THROUGH A DEVICE CALLED A MASTER OSCILLATOR-POWER
AMPLIFIER (MOPA). THE MOPA CONTAINS FOUR THIN LASER AMPLIFIER RODS THAT
BEGIN THE POWER-BOOSTING PROCESS. THESE RODS, COMPOSED OF A GLASS-
LIKE MATERIAL MADE OF NEODYMIUM, YTTRIUM, LITHIUM, AND FLUORIDE, ARE
ABOUT THE SIZE OF THE GRAPHITE INSIDE A PENCIL: JUST 3 MM IN DIAMETER AND
5 CM LONG. TO AMPLIFY THE SEED BEAM, THE MOLECULES IN EACH ROD ARE
FIRST ENERGIZED BY SHINING A SEPARATE 808 NM LASER INTO EACH ONE. WHEN
THE SEED BEAM TRAVELS THROUGH THE FIRST ROD, THE ROD'S MOLECULES
RESPOND BY EMITTING 1064 NM PHOTONS WITH THE SAME PROPERTIES (PHASE,
WAVELENGTH) AS THE INCOMING SEED BEAM. THESE NEW 1064 NM PHOTONS JOIN
THOSE FROM THE SEED BEAM TRAVELING IN THE SAME DIRECTION, AND THE
POWER BOOSTING BEGINS.
LASER
2 7
LIGO
28. (HPO). THE HPO USES FOUR MORE AMPLIFIER RODS, ABOUT THE SAME SIZE AS THE
MOPA'S RODS BUT MADE OF A DIFFERENT MATERIAL. AS THE BEAM PASSES
THROUGH THESE RODS, JUST LIKE IN THE MOPA, IT GETS AN ADDITIONAL POWER
BOOST FROM LASER LIGHT FUNNELED THROUGH BUNDLES OF FIBER-OPTIC
CABLES ARRANGED LIKE A FLOWER SOME 3 MM ACROSS. EACH FIBER CARRIES 45
WATTS OF LASER POWER, SO EACH BUNDLE DELIVERS 315 W (7 FIBERS X 45 W
EACH) INTO EACH HPO ROD TO PRIME IT TO EMIT MORE AND MORE LASER LIGHT.
BY THE TIME THE BEAM EXITS THE HPO IT HAS FINALLY ACHIEVED ITS DESIRED
POWER OF 200 W. THE BEAM’S NATURAL FREQUENCY VARIATIONS (CAUSED BY ITS
INABILITY TO CONTINUALLY RADIATE A SINGLE, DISCRETE COLOR OF LIGHT) AND
POWER FLUCTUATIONS ARE MECHANICALLY REDUCED BY ABOUT A FACTOR OF 100-
MILLION THROUGH A SERIES OF FEEDBACK MECHANISMS BEFORE THE LASER IS
USED IN THE INTERFEROMETER. POWER FLUCTUATIONS ARE ALSO REDUCED
THROUGH FEEDBACK CONTROL LOOPS, WHICH USE PHOTODETECTOR DATA TO
SENSE POWER FLUCTUATIONS.
LASER
2 8
LIGO
30. IS AN IR LASER, ITS OPTICS MUST NOT ABSORB IR RADIATION. DOING SO WOULD RESULT IN
HEATING AND IN SIGNIFICANT CHANGES TO THE SHAPE OF THE MIRRORS, THUS CRITICALLY
AFFECTING LIGO’S ABILITY TO MAKE THE PRECISE MEASUREMENTS IT NEEDS TO MAKE. LIGO’S
MAIN MIRRORS ONLY ABSORB ONE OUT OF EVERY 3.3 MILLION PHOTONS, THE REST BEING
REFLECTED (OR TRANSMITTED). SOME HEATING DOES OCCUR, BUT AN AUXILIARY SYSTEM
USING A CO2 LASER HEATS THE MIRRORS PRECISELY ENOUGH TO COUNTERACT THE SHAPE-
CHANGES THAT OCCUR AS A RESULT OF HEATING FROM LIGO’S MAIN LASER. THE TEST-
MASSES ARE COATED WITH DOZENS OF LAYERS OF OPTICAL COATINGS AND POLISHED TO
NANOMETER SMOOTHNESS. AS THE LASER MAKES 280 REFLECTIONS [TRAVELLING 1120 KMS]
BEFORE MERGING AND HITTING PHOTODIODES.
MIRROR
3 0
LIGO
31. CUSTOMIZED ITS YAG-444AH SILICON PIN PHOTODIODE TO WORK INSIDE THE LIGO
INTERFEROMETER’S EXTREMELY SENSITIVE AND ULTRA-LOW VACUUM CHAMBER. TO ALLOW
THEM TO BE USED WITHIN THE CHAMBERS, EXCELITAS MODIFIED THE SILICON PHOTODIODE BY
ELIMINATING A WINDOW CAP AND USING ONLY MATERIALS THAT WERE CERTIFIED FOR
OPERATION WITHIN THE INTERFEROMETER’S EXACTING ENVIRONMENTAL REQUIREMENTS.
ADDITIONALLY, EXCELITAS PROJECT TEAM MEMBERS CONSULTED AND ASSISTED CLOSELY
WITH LIGO STAFF TO ENSURE THE PROPER CLEANING AND HANDLING OF THESE CUSTOM
PARTS THROUGH INSTALLATION. THIS DETECTOR HELPED MONITOR THE QUALITY OF LASER
BEAMS TRAVELING WITHIN THE VACUUM AT THE TWO LIGO SITES IN HANFORD, WASHINGTON
AND LIVINGSTON, LOUISIANA. IN ADDITION, LIGO USED OFF-THE-SHELF EXCELITAS C30665GH
INGAAS PIN PHOTODIODES TO MEASURE THE RECOMBINED YAG LASER BEAMS AFTER THEY
CAME OUT OF THE INTERFEROMETER'S ARMS. IT MEASURED THE OPTICAL BEAM DISRUPTION
CAUSED BY THE GRAVITATIONAL WAVES, AND GENERATED THE PHOTOCURRENT WHICH WAS
THEN CONVERTED INTO THE AUDIBLE "CHIRP".
SENSORS
3 1
LIGO
32. THE AMOUNT OF DATA LIGO COLLECTS IS AS INCOMPREHENSIVELY LARGE ALL OF THIS
INFORMATION MUST BE TRANSFERRED TO A NETWORK OF SUPERCOMPUTERS FOR
STORAGE AND ARCHIVING. SUCH SUPERCOMPUTERS ARE LOCATED AT EACH OF THE
OBSERVATORIES, AT CALTECH, AT MIT, AND AT VARIOUS OTHER INSTITUTIONS. THE DATA
ARCHIVE AT CALTECH HOLDS OVER 4.5 PETABYTES (PB) OF DATA, AND WILL GROW AT A
RATE OF ABOUT 0.8 PB (800 TERABYTES) PER YEAR. ONCE THE DATA IS SECURED,
SCIENTISTS CAN USE CUSTOMIZED COMPUTER PROGRAMS TO SCOUR THE DATA FOR
GRAVITATIONAL WAVES. FOR LIGO'S FIRST OBSERVING RUN IN 2015, THE LIGO LAB
PROVIDED 35 MSU (MILLION SERVICE UNITS) WORTH OF COMPUTING CYCLES/TIME. THIS
IS EQUIVALENT TO RUNNING A MODERN 4-CORE LAPTOP COMPUTER FOR 1,000 YEARS!
COMPUTATION AND DATA COLLECTION
3 2
LIGO
33. THE
DISCOVERY
3 3
The first direct observation of gravitational waves was made on 14 September 2015 and
was announced by the LIGO and Virgo collaborations on 11 February 2016. The signal
was named GW150914. The waves given off by the cataclysmic merger of GW150914
reached Earth as a ripple in spacetime that changed the length of a 4 km LIGO arm by a
thousandth of the width of a proton, proportionally equivalent to changing the distance to
the nearest star outside the Solar System by one hair's width. The energy released by
the binary as it spiralled together and merged was immense, with the energy of 3.0+0.5
−0.5 c2 solar masses (5.3+0.9 −0.8×1047 joules or 5300+900 −800 foes) in total
radiated as gravitational waves, reaching a peak emission rate in its final few
milliseconds of about 3.6+0.5 −0.4×1049 watts – a level greater than the combined
power of all light radiated by all the stars in the observable universe.
34. RESULTS FROM
OBSERVATIONS
3 4
B2B MARKET
SCENARIOS
Develop winning strategies to keep ahead of the
competition
Capitalize on low hanging fruit to identify a
ballpark value
Visualize customer directed convergence
CLOUD-BASED
OPPORTUNITIES
Iterative approaches to corporate strategy
Establish a management framework from the
inside
LIGO
36. SUMMARY
3 6
As we can all see now every new discovery and every
new answer that we find to our questions about this
mysterious universe is a journey where we always need
to start from scratch till testing and confirming our
hypothesis, involving efforts and brains of many few of
whom we remember and forget the rest who had also
played a significant role in the process, so I guess
today here we should remember all the countless
physicists, mathematicians and 1000s of engineers that
helped us make this astonishing discovery.
