Download - Einsteins Ballerina
Einsteins Ballerina– the discovery of gravitational waves –
Gerco Onderwater
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The plan ...
Before we had gravity
Newton's universal gravity
Einstein's dynamical gravity
LIGOs result
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Recording patterns
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Astronomy & telescopes
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Moon
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Sun
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Planets & Stars
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Tycho Brahe
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Keplers model
Johannes Kepler (1571-1630)Mysterium Cosmographicum (1596)planets move in elliptical orbits, not circles. Why?
Nicolaus Copernicus (1473-1543)De revolutionibus orbium coelestium (1543)sun at the center of the universe?
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Galileo Galilei (1564-1642)Dialogo sopra i due massimi sistemi del mondo (1632)some force keeps planet in orbit
Enter Newton
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Isaac Newton (1642-1727)Philosophiæ Naturalis Principia Mathematica (1687)laws of motion, universal gravition, mathematics
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Gerco Onderwater, 16 February 2016
What about light?
James Clerk Maxwell (1831-1879)A Dynamical Theory of the Electromagnetic Field (1865)unifies electricity, magnetism, and light; introduces c
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Interferometer
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Albert Einstein
Questions
Is gravity instantaneous?
What does light move in?
Why does Mercury not move as expected?
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Galileian relativity
Postulate:
Laws of motion are thesame in all inertialframes
Result:
Absolute space &universal time
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1905 : Einstein's annus mirabilis
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Special relativity
First postulate : the laws of physics have the sameform in all inertial reference frames
Second postulate : light moves through empty spacewith a definite speed c independent of the speed of thesource or the observers
OK!
Weird ...
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Some consequences of SR
time dilation : moving clocks run slower as seen by astationary observer, time slows down
length contraction : length along the direction ofmotion is measure to be slower, space contracts
c : nothing can travel faster than light
E = mc² : mass is a form of energy
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Gerco Onderwater, 16 February 2016
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1915 : General relativity
Postulate : accelerated motion and being at rest ingravitational field equivalent
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Consequences of GR
Free fall = inertial motion (no forces felt)
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Consequences of GR
Space-time dynamically affected by mass
Light bends in gravitational field
Black holes
Expanding universe
Gravitational waves
Eddington 1919
Cygnus X-1 ~1990
Lemaître 1927
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Universe born in “Big Bang” 14 billion years ago
1929 : Hubble observes redshift
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1965 : Big Bang afterglow detected
Radio signal created as light
380,000 years after Big Bang
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Cosmic Microwave Background
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Binary Stars
First detected by Giovanni Battista Riccioli (1650)
GR prediction
Indirect proof of gravitational waves
Hulse & Taylor
PSR B1913+16
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Pirouette
PSR B1913+16Wait for 300M years
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LIGO
Light Interferometer Gravitational wave Observatory
Cofounded in 1992 by Kip Thorne, Ronald Drever, Rainer Weiss
Collaboration : ±1000 scientists / 90+ institutes / 15 countries
Mission : directly observe gravitational waves of cosmic origin
Started in 2002, upgraded in 2015
Two stations : Livingston (LA) & Hanford (WA), 3000km apart
Sensitive to colliding/coalescing binary systems (neutron stars,black holes), supernovae, rotating neutron starts, …, Big Bang
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LIGO principle
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LIGO optics
Seismic noise reduced by 10,000,000,000
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LIGO Hanford (WA)
4km
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LIGO Livingston (LA)
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GW150914 / 14.09.2015 @ 09:50:45 UTC
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GW150914 / 14.09.2015 @ 09:50:45 UTC
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Signal & Interpretation
Peak strain of 1.0 × 10−21 → 1/1,000 of rp / 4km
Black-hole merger, ~30 solar masses each, ~150km diameter
3 solar masses radiated → 3.6×1049 W (= 50x light in universe)
Distance = 1.3Gly (1.26x1025 m)
(= 27l on earth volume; 1ml / Atlantic ocean; 1 grain / IJsselmeer)
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Fake rate : 1 in 203,000 years
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Reach
Increase sensitivity → cubedincrease in #candidates
Study strong gravity → new!
Study star formation → new options
New tool!Study very early universe →otherwise inaccessible
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LIGO & Beyond
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Gerco Onderwater, 16 February 2016