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Gravitational Waves Earth expands and contracts by the diameter of an atomic  nucleus: Gravitational Waves Earth expands and contracts by the diameter of an atomic  nucleus:

Gravitational Waves Earth expands and contracts by the diameter of an atomic nucleus: - PowerPoint Presentation

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Gravitational Waves Earth expands and contracts by the diameter of an atomic nucleus: - PPT Presentation

12 cm A worldshaking discovery James Clerk Maxwell Professor at Kings College London 1860 1865 Unified theory of electricity and magnetism Predicted electromagnetic waves Identified light as due to these waves ID: 811296

masses ligo black gravitational ligo masses gravitational black amp arxiv waves solar einstein experiment laser space agreement interferometer measured

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Presentation Transcript

Slide1

Gravitational Waves

Earth expands and contracts by the diameter of an atomic nucleus: 10

-12

cm

A world-shaking discovery

Slide2

James Clerk Maxwell

Professor at King’s College

London: 1860 – 1865Unified theory of electricity and

magnetismPredicted electromagnetic wavesIdentified light as due to these wavesCalculated the velocity of light…One scientific epoch ended and another began with James Clerk Maxwell - Albert Einstein

Slide3

Electromagnetic Waves

Proposed by Maxwell

Discovered by Hertz

A lot to answer for ….Nobody knows where fundamental physics may lead

Slide4

Gravitational Waves

General relativity proposed by Einstein 1915

He predicted gravitational waves in 1916

Slide5

Gravitational Wave Spectrum

A new type of astronomy

Slide6

First Attempts at Detection

1970s: Metal bars

(Joseph Weber)Also Explorer experiment at CERN

Slide7

Indirect Detection

Binary pulsar discovered 1974 (

Hulse & Taylor)Emits gravitational wavesChange in orbit measured

for years Perfect agreement with Einstein Nobel Prize 1993

Slide8

Discovery of Gravitational Waves

Measured by the LIGO experiment in 2 locations

State of Washington

State of Louisiana

Slide9

LIGO experiment

Inteference

between 2 laser beams measures the expansion and contraction of space

Slide10

Principle of Laser Interferometer

Inteference

between 2 laser beams measures the expansion and contraction of space

ReinforceCancel outMirrorMirror

Laser

Mirror

Slide11

Installing LIGO Experiment

Slide12

LIGO Experimental Apparatus

Slide13

LIGO Layout & Sensitivity

Earth’s diameter changes by

<< size of atomic nucleus

Slide14

Fusion of two massive black holes

Masses ~ 36, 29 solar masses

Radiated energy ~ 3 solar masses

Slide15

What was observed

Very similar signals in the 2 detectors

In agreement with gravitational-wave predictions

Slide16

Fusion of two massive black holes

Einstein was right

A new way to study the Universe

Slide17

The Gravitational Chirp …

… heard around the world

Frequency increases with time during

inspiralFollowed by ringdown of combined black holeGraviton mass < 10-27 × mass of electronWaves of different frequencies have same speedJE, Mavromatos & Nanopoulos, arXiv:1602.04764LIGO

Slide18

GW150914, GW131226 & LVT151012

LIGO & Virgo, arXiv:1606.04764

Slide19

Inferred Black-Hole Masses

LIGO & Virgo, arXiv:1606.04764

GW150914

GW151226

Slide20

Solar masses

X-Ray Studies

First LIGO

event70605040302010 0Other LIGOevents

Measured Black Hole Masses

Recent

LIGO

event

Slide21

The Chirp from GW170401

Frequency increases with time (

inspiral)Similar signals in both detectors ~ GW model

Combined limit on graviton mass< 1.5 × 10-28 melectronLIGO, arXiv:1706.01812In agreement with gravitational-wave predictions

Slide22

GW170104 Black Hole Masses

Before

After

~ 31.2, 19.4 solar masses

~ 48.7 solar masses

LIGO, arXiv:1706.01812

Slide23

Ground-Based GW Detectors

Slide24

Future Step: Interferometer in Space

Slide25

Future Step: Interferometer in Space

Slide26

Was that you I heard just now, or was it two black holes colliding?

Slide27

LIGO GW detections

Excellent video explanation:

http

://motls.blogspot.ch/2016/02/brian-greenes-ligo-colbert-lecture-was.html