Download LewisClark - LIGO | Hanford

Tuning into Einstein’s Unfinished Symphony:
The Search for Gravitational Waves
"Colliding Black Holes"
Credit:
National Center for Supercomputing
Applications (NCSA)
Fred Raab,
LIGO Hanford Observatory
LIGO-G050093-00-W
Einstein’s Legacy in Science

Annus mirabilis, 1905
»
»
»
»



Special Relativity: 1st installment on a theory of space and time
Theory of Brownian Motion: ends debate on the existence of atoms
Quantum Theory of Light: cornerstone of quantum mechanics
Equivalence of matter and energy: E=mc2
Opus Magnus: The General Theory of Relativity, 1916
A new form of matter: Bose-Einstein Particles
Questioning the reality of Quantum Mechanics
» Einstein-Podalsky-Rosen Paradox & hidden variables

Unfinished work:
» Search for a unified “Theory of Everything”
» Detection of Gravitational Waves
LIGO-G050093-00-W
Tuning into Einstein's Unfinished Symphony
2
The Essence of General Relativity

Space and time are things, not concepts
» 1905 – Relativity refers to the “relative” interpretations of space and
time by moving observers; only the speed of light is not relative
» Energy and matter are equivalent and transformable into each
other (E=mc2)
» 1916 – General Theory of Relativity - Space and time affect the
motion of objects and objects warp space and time; gravity is the
natural movement of stuff flowing through warped space and time.
» 1919 – Space warp caused by the sun is detected
» 1950’s and onward– Atomic timekeeping devices reveal time
warps
Gravity and the speed of light are physical properties of
empty space!
LIGO-G050093-00-W
Tuning into Einstein's Unfinished Symphony
3
General Relativity: A Picture Worth
a Thousand Words
LIGO-G050093-00-W
Tuning into Einstein's Unfinished Symphony
4
Mass Warps Space, Affecting
Paths of Objects and Light


Presence of mass gives space the
appearance of lumpy glass as
evidenced by the bending of light
First observed during the solar eclipse
of 1919 by Sir Arthur Eddington, when
the Sun was silhouetted against the
Hyades star cluster
A massive object shifts
apparent position of a star
Einstein Cross
Photo credit: NASA and ESA
LIGO-G050093-00-W
Tuning into Einstein's Unfinished Symphony
5
The Frontier of Relativity:
Gravitational Waves
Gravitational waves
are ripples in space
when it is stirred up
by rapid motions of
large concentrations
of matter or energy
LIGO-G050093-00-W
Rendering of space stirred by
two orbiting black holes:
Tuning into Einstein's Unfinished Symphony
6
Einstein Died Believing Gravitational
Waves Would Never Be Detected
Never say never…
LIGO-G050093-00-W
Spacetime is Stiff!
=> Wave can carry huge energy with miniscule amplitude!
h ~ (G/c4) (ENS/r)
LIGO-G050093-00-W
Tuning into Einstein's Unfinished Symphony
8
Gravitational Collapse and Its
Outcomes Present Opportunities
fGW > few Hz
accessible from
earth
fGW < several kHz
interesting for
compact objects
LIGO-G050093-00-W
Tuning into Einstein's Unfinished Symphony
9
Supernova: Death of a Massive
Star
•Spacequake should preceed optical
display by ½ day
•Leaves behind compact stellar
core, e.g., neutron star, black hole
•Strength of waves depends on
asymmetry in collapse
Credit: Dana Berry, NASA
•Observed neutron star motions
indicate some asymmetry present
•Simulations do not succeed from
initiation to explosions
LIGO-G050093-00-W
Tuning into Einstein's Unfinished Symphony
10
Gravitational Waves From
Orbiting Black Holes and Neutron Stars
Sketches courtesy
of Kip Thorne
LIGO-G050093-00-W
Tuning into Einstein's Unfinished Symphony
11
Emission of Energy by Gravitational
Waves Has Been Observed
Emission of gravitational waves
Neutron Binary System – Hulse &
Taylor
PSR 1913 + 16 -- Timing of pulsars

17 / sec

~ 8 hr
Neutron Binary System
• separated by 106 miles
• m1 = 1.4m; m2 = 1.36m; e = 0.617
Prediction from general relativity
• spiral in by 3 mm/orbit
Hulse, Taylor
receive Nobel Prize
• rate LIGO-G050093-00-W
of change orbital period
Tuning into Einstein's Unfinished
Symphony
12
Why go beyond light? Because of
where light cannot go.
First light from the universe
Images of light from Big Bang imply
95% of the universe is composed of
dark matter and dark energy. What is
this stuff?
WMAP Image of Relic
Light from Big Bang
What was it like at the birth of space
and time?
LIGO-G050093-00-W
Tuning into Einstein's Unfinished Symphony
13
How can we detect spacetime
vibrations?
Leonardo da Vinci’s Vitruvian man
LIGO-G050093-00-W
Basic Signature of Gravitational
Waves
LIGO-G050093-00-W
Tuning into Einstein's Unfinished Symphony
15
Sketch of a Michelson
Interferometer
End Mirror
End Mirror
Beam Splitter
Laser
LIGO-G050093-00-W
Viewing
Screen
Tuning into Einstein's Unfinished Symphony
16
New Generation of “FreeMass” Detectors Now Online
suspended mirrors mark
inertial frames
antisymmetric port
carries GW signal
Symmetric port carries
common-mode info
Intrinsically broad band and size-limited by speed of light.
LIGO-G050093-00-W
Tuning into Einstein's Unfinished Symphony
17
The Laser Interferometer
Gravitational-Wave Observatory
LIGO (Washington)
LIGO (Louisiana)
Brought to you by the National Science Foundation; operated by Caltech and MIT; the
research focus for more than 500 LIGO Scientific Collaboration members worldwide.
LIGO-G050093-00-W
Tuning into Einstein's Unfinished Symphony
18
The LIGO Observatories
LIGO Hanford Observatory (LHO)
H1 : 4 km arms
H2 : 2 km arms
LIGO Livingston Observatory (LLO)
L1 : 4 km arms
Adapted
NASA
from “The Blue Marble: Land Surface, Ocean Color and Sea Ice” at visibleearth.nasa.gov
Goddard Space Flight Center Image by Reto Stöckli (land surface, shallow water, clouds). Enhancements by Robert Simmon (ocean
color, compositing, 3D globes, animation). Data and technical support: MODIS Land Group; MODIS Science Data Support Team; MODIS
Atmosphere Group; MODIS Ocean Group Additional data: USGS EROS Data Center (topography); USGS Terrestrial Remote Sensing Flagstaff
Field Center (Antarctica); Defense Meteorological Satellite Program (city lights).
The International Interferometer
Network
Simultaneously detect signal (within msec)
LIGO
GEO
Virgo
TAMA
detection
confidence
locate the
sources
AIGO
LIGO-G050093-00-W
Tuning into Einstein's Unfinished Symphony
decompose the
polarization of
gravitational
waves
20
How Much Will the 4-km Mirror
Separation Change?
One meter, about 40 inches
 10,000
100
Human hair, about 100 microns
Wavelength of light, about 1 micron
 10,000
Atomic diameter, 10-10 meter
 100,000
Nuclear diameter, 10-15 meter
 1,000
LIGO-G050093-00-W
LIGO sensitivity, 10-18 meter
Tuning into Einstein's Unfinished Symphony
21
Core Optics Suspension and
Control
Optics
suspended
as simple
pendulums
Local sensors/actuators provide
damping and control forces
Mirror is balanced on 1/100th inch
diameter wire to 1/100th degree of arc
LIGO-G050093-00-W
Tuning into Einstein's Unfinished Symphony
22
Vacuum Chambers Provide Quiet
Homes for Mirrors
View inside Corner Station
Standing at vertex
beam splitter
LIGO-G050093-00-W
Tuning into Einstein's Unfinished Symphony
23
Vibration Isolation Systems
»
»
»
»
Reduce in-band seismic motion by 4 - 6 orders of magnitude
Little or no attenuation below 10Hz
Large range actuation for initial alignment and drift compensation
Quiet actuation to correct for Earth tides and microseism at 0.15 Hz during
observation
HAM Chamber
LIGO-G050093-00-W
Tuning into Einstein's Unfinished Symphony
BSC Chamber
24
Seismic Isolation – Springs and
Masses
damped spring
cross section
LIGO-G050093-00-W
Tuning into Einstein's Unfinished Symphony
25
Seismic System Performance
HAM stack
in air
BSC stack
in vacuum
102
100
102
10-
10-6
Horizontal
4
106
108
LIGO-G050093-00-W
Tuning into Einstein's Unfinished Symphony
10-10
Vertical
26
Evacuated Beam Tubes Provide
Clear Path for Light
LIGO-G050093-00-W
Tuning into Einstein's Unfinished Symphony
27
All-Solid-State Nd:YAG Laser
Custom-built
10 W Nd:YAG Laser,
joint development with
Lightwave Electronics
(now commercial product)
Cavity for
defining beam geometry,
joint development with
Stanford
Frequency reference
cavity (inside oven)
LIGO-G050093-00-W
Tuning into Einstein's Unfinished Symphony
28
Core Optics

Substrates: SiO2
» 25 cm Diameter, 10 cm thick
» Homogeneity < 5 x 10-7
» Internal mode Q’s > 2 x 106

Polishing
» Surface uniformity < 1 nm rms
» Radii of curvature matched < 3%

Coating
» Scatter < 50 ppm
» Absorption < 2 ppm
» Uniformity <10-3

Production involved 6 companies, NIST, and LIGO
LIGO-G050093-00-W
Tuning into Einstein's Unfinished Symphony
29
And despite a few difficulties,
science runs started in 2002…
LIGO-G050093-00-W
Tuning into Einstein's Unfinished Symphony
30
LIGO-G050093-00-W
Tuning into Einstein's Unfinished Symphony
31
Binary Neutron Stars:
S1 Range
LIGO-G050093-00-W
Tuning into Einstein's Unfinished Symphony
32
Image: R. Powell
Binary Neutron Stars:
Initial LIGO Target Range
S2 Range
LIGO-G050093-00-W
Tuning into Einstein's Unfinished Symphony
33
Image: R. Powell
What’s next? Advanced LIGO…
Major technological differences between LIGO and Advanced LIGO
40kg
Quadruple pendulum
Sapphire optics
Silica suspension fibers
Initial Interferometers
Active vibration
isolation systems
Open up wider band
Reshape
Noise
Advanced Interferometers
High power laser
(180W)
LIGO-G050093-00-W
Tuning into Einstein's Unfinished Symphony
Advanced interferometry
34
Signal recycling
Binary Neutron Stars:
AdLIGO Range
LIGO Range
LIGO-G050093-00-W
Tuning into Einstein's Unfinished Symphony
Image: R. Powell
35
…and opening a new channel with
a detector in space.
Planning underway for space-based detector, LISA, to open up a
lower frequency band ~ next decade
LIGO-G050093-00-W
Tuning into Einstein's Unfinished Symphony
36
Closing remark
The age of discovery has not ended…
LIGO-G050093-00-W
Tuning into Einstein's Unfinished Symphony
37
Recommended Reading



“Was Einstein Right”, by Clifford Will. A bit ancient
(more than 10 years old) accounting of progress in
verifying Einstein’s theory.
“Black Holes and Time Warps: Einstein’s Outrageous
Legacy”, by Kip Thorne. From basics to time travel in
a long, but rewarding read.
“Einstein’s Unfinished Symphony”, by Marcia
Bartusiak. A highly readable account of the search for
gravitational waves.
LIGO-G050093-00-W
Tuning into Einstein's Unfinished Symphony
38