1. The 2017 Nobel Prize in Physics "for decisive contributions to the LIGO detector and the observation of gravitational waves"
Peter Berg
Department of Science
University of Alberta
Source:

2. Gravitational waves: Three ingredients
Clocks can tick at different rates (time is relative)
Gravitational fields can warp space (space is relative)
Accelerating masses keep changing space-time
How?

3. We observe time dilation!
Time is relative
The speed of light, c, is constant.
It has the same value in all reference frames.
We observe time dilation!

4. https://physics.aps.org/articles/v9/17
Warping space
Gedankenexperiment #1: Equivalence Principle
The accelerated observer, or equivalently an observer in a gravitational field, observes bent light trajectories!

5. Time in a gravitational field
Gedankenexperiment #2: Free fall in a gravitational field
We observe different time dilation in a gravitational field!

6. Einstein’s field equations of general relativity
“Simple” concept: mass-momentum distribution determines space-time:
Equations have “just” the right (relativistic) form!
Everything moves according to a minimization principle
⇒ new distribution of matter ⇒ new space-time metric
And so forth…
Above equations allow for gravitational waves, moving at speed of light & produced by accelerated masses, similar to electro-magnetic waves, moving at c & produced by accelerating charges.
Causing minuscule changes in distance of objects (𝟏 in 𝟏𝟎 𝟐𝟐 )
Einstein: “This can never be measured!”

7. Physics Nobel Prize Winners 2017
Reiner Weiss (*1932, Berlin, Germany) PhD from MIT LIGO/VIRGO Collaboration, MIT interferometer, noise reduction, data collection (1/2)
Barry Barish (*1936, Omaha, USA) PhD from University of California, Berkeley LIGO/VIRGO Collaboration, Caltech PI & Director, LIGO (Hanford, WA; Livingston, LA); LIGO collaboration (1/4)
Kip Thorne (*1940, Logan, USA) PhD from Princeton University LIGO/VIRGO Collaboration, Caltech prediction of signature; wormholes & time travel; Interstellar (1/4)

8. LIGO: Observing gravitational waves
Tiny effect
amidst a lot
of noise
⇒ gigantic
interferometer!
Laser
Interferometer
Gravitational-
wave
Observatory

9. What was observed first?
14 Sep 2015: (5x by now)
Two black holes merging (predicted theoretically) 1.3 billion years ago.
Happens very quickly (0.1s).
Correlation between several interferometers.

10. What was observed first?.

11. What is so special about this?
Gravitational waves pass through all matter, electro-magnetic waves do not.
⇒ Looking deeper into space, i.e. further back in time (closer to Big Bang), then currently possible (Cosmic Microwave Background Radiation; 𝑡=380,000 years)
Proof of existence of black holes
Study new dynamics

12. What is so special about this?.

13. Observing gravitational waves: The future
Besides several current interferometers (2x USA, x Germany, 1x Italy), there is space: LISA
And then there is the Warp Drive…