3GR

The Search for Black Holes and Gravitational Waves:The Ultimate Tests of Einstein’s Relativity: 

Edmund Bertschinger MIT Department of Physics and Kavli Institute for Astrophysics and Space Research The Search for Black Holes and Gravitational Waves: The Ultimate Tests of Einstein’s Relativity

What is a black hole?: 

What is a black hole? A massive spacetime curvature singularity, Surrounded by an event horizon (a point or ring of infinite density and tidal acceleration) (a spacetime boundary between causally disconnected regions of the universe)

Einstein’s Strangest Theory:Curved Space, Warped Time: 

Einstein’s Strangest Theory: Curved Space, Warped Time The gravity of massive objects can make space non-Euclidean: Cosmology: Black hole:

Are Black Holes Giant Spacetime Trampolines?: 

Are Black Holes Giant Spacetime Trampolines? Figure from NASA/GSFC Imagine What does Stephen Hawking say?

Einsteinian time warps: 

Einsteinian time warps Minkowski diagram without a black hole My worldline (trajectory) If you pass inside this cone, I can communicate with you!

Slide6: 

i was considering how within night's loose sack a star's nibbling in- fin -i- tes- i -mal- ly devours darkness the hungry star which will e . -ven tu- al -ly jiggle the bait of dawn and be jerked into eternity. when over my head a shooting star Burs (t into a stale shriek like an alarm-clock) -- e.e. cummings Collapse through the horizon: N. Rumiano, http://nrumiano.free.fr/Eindex.html

What happens at the event horizon?: 

What happens at the event horizon? Classically, nothing — it’s just a dangerous border crossing. Quantum mechanically, Hawking radiation Particle vacuum state fluctuates with creation/annihilation of virtual pairs of particles Negative energy particles fall in, positive energy ones escape, black hole loses mass as blackbody radiation Completely negligible for astrophysical black holes

How can matter escape from a BH?: 

How can matter escape from a BH? Quantum tunneling produces a Particle-Antiparticle pair from the vacuum! http://superstringtheory.com/blackh/blackh3.html Hawking radiation is extremely weak and may never be observed. Yet it raises profound questions of quantum gravity that perhaps only Superstring Theory will be able to answer!

Black holes in Nature: 

Black holes in Nature The afterlife of giant stars Black hole masses 3-15 solar masses Giant sinkholes in galaxy centers Black hole masses million to billion solar masses

How we find black holes (and neutron stars): X-rays!: 

How we find black holes (and neutron stars): X-rays! MIT-led Rossi X-Ray Timing Explorer satellite, launched 1995

How do black holes emit X-rays?: 

How do black holes emit X-rays? They get indigestion from eating a companion star, which gets compressed and heated in an accretion disk! Artistic conception 1 Artistic conception 2

How can we prove these are the BH of Einstein’s theory?: 

How can we prove these are the BH of Einstein’s theory? Measure the gravitational waves emitted as two black holes merge.

Gravitational Radiation: 

Gravitational Radiation Newtonian gravity is action at a distance, in clear violation of the principle of relativity. How does general relativity fix this? By adding WAVES that travel at the speed of light How are they produced and how are scientists preparing to detect them? Produced by accelerating masses: for example, two black holes merging Detected by their TINY effect on test masses, using LASERS bouncing back and forth between moving mirrors

Gravitational waves — the Evidence: 

Neutron Binary System – Hulse & Taylor (Nobel Prize) PSR 1913 + 16 -- Timing of pulsars · · 17 / sec 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 rate of change orbital period ~ 8 hr Gravitational waves — the Evidence

Slide15: 

Left: Artist’s conception of gravitational waves produced by a binary system Bottom: LIGO design http://www.ligo.caltech.edu/

Effect of a GW on matter: 

Effect of a GW on matter

Global network of detectors: 

Global network of detectors LIGO LIGO LISA VIRGO TAMA GEO Detection confidence Source polarization Sky location AIGO

LIGO: Laser Interferometer Gravitational-wave Observatory: 

LIGO: Laser Interferometer Gravitational-wave Observatory LA WA 4 km 2 km 4 km

Science Runs and Sensitivity: 

Science Runs and Sensitivity DL = strain x 4000 m 10-18 m rms

H1 strain sensitivity – S1 to S4+: 

H1 strain sensitivity – S1 to S4+

What’s the latest? S5 (goals): 

What’s the latest? S5 (goals) Sensitivity (in terms of inspiral reach) H1 11 Mpc (10 to 14 Mpc) H2 5 Mpc (6 to 9 Mpc) L1 11 Mpc (10 to 14 Mpc) Stability and duty cycle 70% individual 40% triple coincidence Schedule Started in November, 2005 Get 1 year of data at design sensitivity Enhancements over next 3 years Advanced LIGO: 2008, 15 times more sensitive than initial LIGO

Laser Interferometer Space Antenna (LISA, 2013+): 

Laser Interferometer Space Antenna (LISA, 2013+) 1 AU = 1.5x108 km Three spacecraft triangular formation separated by 5 million km Formation trails Earth by 20° Approx. constant arm-lengths Constant solar illumination

LISA and LIGO: 

LISA and LIGO

Ultimate success…New Instruments, New Field, the Unexpected…: 

Ultimate success… New Instruments, New Field, the Unexpected…

Special Thanks to: 

Special Thanks to Prof. Nergis Mavalvala and the LIGO Scientific Collaboration YOU can get involved in LIGO data analysis: “Einstein at Home” http://einstein.phys.uwm.edu/

Additional Credits and Information: 

Additional Credits and Information Credits: Black hole animated gif courtesy Andrew J.S. Hamilton Rossi X-Ray Timing Explorer figure courtesy NASA/Goddard Space Flight Center LIGO and other gravitational wave images courtesy Nergis Mavalvala Stephen Hawking’s voice was simulated and used without permission. Books: The Elegant Universe: Superstrings, Hidden Dimensions, and the Quest for the Ultimate Theory, Brian Greene (more advanced than The Fabric of the Cosmos) Black Holes and Time Warps: Einstein’s Outrageous Legacy, Kip S. Thorne (more advanced)