Gravitational waves are disturbances in spacetime generated by accelerated masses that propagate outward from their source at the speed of light. Measuring gravitational waves provides a new way to observe the universe, as gravitational waves can travel to us from regions of spacetime that light cannot reach. The first direct detection of gravitational waves in 2015 using the LIGO detectors confirmed predictions of Einstein's theory of general relativity and detected the merger of two black holes over 1 billion light years away.

1. Gravitational Waves
A n e w e r a i n a s t r o n o m y
• D r. I . B u d i n c e v i c & D r. V. Ya z i c i

2. Agenda
● Motivation
● Why should you care?
● Why does gravitational waves matter?
● Gravitational waves
● What is space-time?
● What is gravity?
● What are gravitational waves?
● Measuring Gravitational waves
● F.A.Q.

3. Why should you care?

4. 0
2750 BC
1761 AD
Time
Ancient Egyptian texts
referring to shocks
of electric fish.
600 BC
Observations made by
Thales using feathers,
cat’s fur, rods of amber, etc.
2150 years!
1600 AD
William Gilbert coined the New Latin word
electricus ("of amber" or "like amber",
from elektron, the Greek word for "amber")
to refer to the property of attracting
small objects after being rubbed.
Ebenezer Kinnersley
demonstrated heating a
wire to incandescence.

5. Kijk Amsterdam 1700-1800
Hey! Now I will
heat this wire
and it will start
shining!
Goed
verhaal…

6. Why do gravitational waves matter?

8. The observable universe is a spherical region of the universe comprising all
matter that can be observed from Earth at the present time, because
electromagnetic radiation from these objects has had time to reach Earth
since the beginning of the cosmological expansion.
“Observable universe”, Wikipedia

9. The observable universe is a spherical region of the universe comprising all
matter that can be observed from Earth at the present time,
because electromagnetic radiation from these objects
has had time to reach Earth since the beginning of the cosmological
expansion.
“Observable universe”, Wikipedia

10. In physics, radiation is the emission or transmission of energyin
the form of waves or particles through space or through a material medium.
● acoustic radiation, such as ultrasound, sound, and seismic waves (dependent on a physical
transmission medium)
● electromagnetic radiation, such as radio waves, microwaves, visible light, x-rays, and
gamma radiation (γ)
● particle radiation, such as alpha radiation (α), beta radiation (β), and neutron radiation
(particles of non-zero rest energy)
● gravitational radiation, radiation that takes the form of gravitational waves, or ripples in
the curvature of spacetime. NEW!

12. Things we have covered:
1. Why you should care?
2. Why do gravitational waves matter?
Things you actually need:
1. What is gravity?
2. What are gravitational waves?

13. What is gravity?

14. What is gravity?What is gravity?

15. What is gravity?What is gravity?

16. How do we explain gravity?
“Time, space and gravitation have no separate existence from matter”.
Albert Einstein

17. What is space-time?

18. Gravity = mass bends space-time

20. Extreme bending -> black holes

21. What is a gravitational wave?

22. Gravitational waves are the disturbances in the fabric ("curvature") of
spacetime generated by accelerated masses and propagate as waves
outward from their source at the speed of light.
“Gravitational wave”, Wikipedia

23. Gravitational waves are the disturbance in the
fabric ("curvature") of spacetime generated by accelerated
masses and propagate as waves outward from their source at the
speed of light.
“Gravitational wave”, Wikipedia

24. What are gravitational waves?

27. 3,000
km
LIVINGSTON
U S A
HANFORD
The Hanford facility is on the steppes
of the northwest USA, outside Hanford.
The Livingston facility is in Livingston in
the southern swampland of Louisiana.
FIG 4. LIGO consists of two gigantic identical interferometers. The
gravitational wave first hit the interferometer in Livingston and then
passed its twin in Hanford, just over 3,000 km away, 7 milliseconds
later. The signals were almost identical, and were a good match
with the predicted signal for a gravitational wave. Using the signals,
an area in the southern skies could also be identified as the area
the waves came from.
Courtesy Caltech MIT/Ligo Laboratory
Courtesy Caltech MIT/Ligo Laboratory

29. HANFORD LIGO
BLACK HOLES
SOLAR MASSES SOLAR MASSES SOLAR MASSES
Energy equivalent to
three solar masses was
emitted over a few
tenths of a second.
29
GRAVITATIONAL WAVES FROM
COLLIDING BLACK HOLES
36
COSMIC CHIRPS
62
Illustration: ©Johan Jarnestad/The Royal Swedish Academy of Sciences

31. Extreme bending -> black holes

32. F.A.Q.
● Can we travel (or observe) faster than the speed of light?
● Does this enable teleportation?
● Can we beat gravity?
● Can I experience this myself?
● Do you still recommend to watch Interstellar?

33. Thanks, any questions?

35. Extra slides