Gravitational waves are ripples in spacetime that travel at the speed of light and are generated by massive accelerating objects like black holes and neutron stars. They have long wavelengths compared to the size of the objects that produce them. LIGO detects gravitational waves by measuring tiny changes in the lengths of its arms caused by passing gravitational waves. The first direct observation of gravitational waves in 2015 confirmed their existence and provided insights into black holes and the universe.

2. Ripples or Oscillations in space time
Travel at the speed of light
Comes from very massive objects
Strength of waves ∝ 1 / distance from the source
It can penetrate regions of space that electromagnetic waves
cannot

3. SUPERNOVAE AND STARS COLLAPSE INTO NEUTRON
STAR
TWO BLACK HOLES COLLIDING OR ORBITING EACH
OTHER
NEUTRON STAR ORBITING A BLACK HOLE
A ROTATING NEUTRON STAR
COLLIDING GALAXIES

4. Astronomical event that occurs during the last
stellar evolutionary stages of a massive star's life

5. Interacting galaxies (colliding galaxies) are galaxies whose gravitational fields result
in a disturbance of one another

6. BLACK HOLE
A region of space-time exhibiting such strong gravitational effects.
Sufficiently compact mass can deform space-time to form a black hole.

7. Neutron stars are created when giant stars die in supernovas and their cores collapse,
with the protons and electrons essentially melting into each other to form neutrons.

8. How will we detect gravitational
waves?

9. Follow the beam: schematic showing a LIGO
interferometer

11. • prove the existence of the gravitational waves by
direct measurements
• Confirm that Gravitational waves travel at the speed of
light
• Verify that gravitational waves cause disturbances of
predicted amounts in the matter they pass through
• Learn more about black holes
• Expand knowledge about universe

12. CHANGE IN LENGTH OF LIGO’S ARM

13. Detected on September 14, 2015 at 09:50:45 UTC
−
B. P. Abbott et al
PHYSICALREVIEW LETTERS
116, 061102 (2016)

14. WHY STUDY GRAVITATIONAL WAVES
Can accurately determine cosmological distances.
Instrument made for gravitational wave detection is the most
precise measuring system ever.
Gravitational-wave astronomy is an emerging branch of
observational astronomy which aims to use gravitational waves to
collect observational data Such as neutron stars and black holes

15. COMPARISON
GRAVITATIONAL WAVES
• weak force
• generated by the bulk motion of
large masses, and will have
wavelengths much longer than
the objects themselves
• Gravitational charge is
equivalent to inertia.
• difficult to detect
• they can travel unhindered
through intervening matter of
any density or composition
ELECTROMAGNETIC WAVES
• Stronger force
• typically generated by small
movements of charge pairs within
objects, and have wavelengths
much smaller than the objects
themselves.
• charge is unrelated to inertia.
• easy to detect
• readily absorbed or scattered by
intervening matter.

16. • To prove the existence of the gravitational waves by
direct measurements
• Confirm that Gravitational waves travel at the speed of
light
• Verify that gravitational waves cause disturbances of
predicted amounts in the matter they pass through
• Learn more about black holes
• Expand knowledge about universe

17. 1. Observation of Gravitational Waves from a Binary Black Hole Merger
PHYSICAL REVIEW LETTERS
B. P. Abbott et al.*
(LIGO Scientific Collaboration and Virgo Collaboration)
https://physics.aps.org/featured-article-pdf/10.1103/PhysRevLett.116.061102
2.LIGO lab Caltech MIThttps://www.ligo.caltech.edu/
3. Gravitational waves-wikipedia
https://en.wikipedia.org/wiki/Gravitational_wave
4. J. Abadie et al. (LIGO Scientific Collaboration, Virgo Collaboration)
Phys. Rev. D 85, 082002 – Published 19 April 2012
http://journals.aps.org/prd/abstract/10.1103/PhysRevD.85.082002

18. GRAVITATIONAL WAVES ELECTROMAGNETIC WAVES
• Stronger force
• typically generated by small
movements of charge pairs within
objects, and have wavelengths much
smaller than the objects themselves.
• charge is unrelated to inertia.
• easy to detect
• readily absorbed or scattered by
intervening matter.