How Do You Detect a Black Hole? LIGO and the Measurement of Gravitational Waves

Until 2015, scientists could only infer the existence of theoretical black holes. But everything changed when the LIGO experiment detected gravitational waves from the collision of two binary black holes 1.3 billion light-years from Earth. In this program, Brain Greene talks to Vicky Kalogera, a leading member of the LIGO Collaboration, about the inner workings of the LIGO detector—the most accurate measuring device humans have ever built—and what we've learned about black holes and the fabric of the universe since this monumental discovery.

PARTICIPANT: Vicky Kalogera

MODERATOR: Brian Greene

This program is part of the BIG IDEAS SERIES, made possible with support from the JOHN TEMPLETON FOUNDATION.

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TOPICS:

0:07 - Einstein’s theory on gravitational waves
3:18 - Vicky Kalogera intro
3:57 - What is LIGO?
5:57 - How did LIGO detect gravitational waves?
7:40 - What causes gravitational waves?
10:25 - What was the signal like when the waves were generated?
12:56 - Converting the gravitational wave signal into sound
18:40 - Calculating and simulating gravitational waves
20:21 - Detecting neutron star collisions
25:38 - What did we learn from the neutron star collision discovery?
28:26 - How are these discoveries testing Einstein’s theory of general relativity?

PROGRAM CREDITS:

- Produced by John Plummer
- Associate Produced by Laura Dattaro
- Animation/Editing by Josh Zimmerman
- Music provided by APM
- Additional images and footage provided by: Getty Images, Shutterstock, Videoblocks

This program was recorded live at the 2018 World Science Festival and has been edited and condensed for YouTube.

[quahntasy]

Guys its a reupload.


Just in case you were wondering.

[teashea]

These one on one sessions are even better than the panel discussions

[TeunLos]

It's a reupload if you wondering.

[ericsalles]

How awesome (if you dont look at the screen) to have Zsa Zsa Gabor explain gravitational waves

[Lightning_Lance]

Me reading the description:

Until 2015, scientists could only infer the existence of theoretical black holes. But everything changed when the fire nation attacked...

[jmcistntable]

A man who was only concerned about being right. Not for the sake of pride but for the benefits of his predecessors. A brilliant man

[Doodlebud]

So not only did we confirm an idea that one of the greatest minds in humanity has ever hypothesized by making the most difficult and precise measurement EVER....it also as a biproduct confirmed how gold is formed. Oh yeah, and now that we can measure & study gravitational waves to gain a better understanding of them, the long term outcome of that is through that understanding we may one day be able to produce gravitational waves. Thus, potentially allowing us to create gravitational based motion systems to explore the universe. All that, and this video only has 35K view. Meanwhile, a video entitled "me at the zoo" has 237M views! My brain hurts 🤔😣😫

[ajit_edu]

15.34 I suppose she meant Sound waves are longitudinal wave (not transverse)

[HardRockMiner]

I just use my fingers. It gets easier and easier the more you do it. The are all pretty much in the same locations anyway. Glad I could help.

[allroundersmedicine]

5:57
Oh! I was just about ask the same question.

[ndclasscanadian]

Is the black hole our best evidence so far of interactions with the Higgs field?

[markdamen]

did this in my first year, if a collapse through space /time happens there would be a bend in gravity and light, hmmm lensing?

[thoughtexperimentsbybk]

Is there a change density of the earth during this disturbance

[aurelienyonrac]

28:54 we always try to test enstin. He made, i mean his theory must break down because it involves the singularity. Deviding by 0 doesn't make sense"
Could it be that here understanding is about to break down and she will have a break through.
One devided by 0 equal all and any number.
In other words, any number is one/a number.

[PaulHigginbothamSr]

If the dark matter surrounding galaxies is primordial black holes by the millions, there is no possible way to tell that if they may be less than a solar mass. Or even 1/10th that. If 1/100th that then by statistical probability some should be evaporating, and since they are not they would seem slightly larger.

[devikab.s.]

How it was ensured that gold was formed in neutron star collisions?

[techsinc]

The thing that bothers me is that for us to be so lucky to detect this coming from a billion light years away, means unless we are one in a billion lucky, there are on average of order billion or millions of such things going on somewhere in the universe at any moment?

[charlesashurst]

Don't get me wrong. What they did was real good. But, if they could just take a 3D photo of a black hole, that'd be good.

[Jason-gtkx]

With all the new evidence of GR and how spacetime reacts, I have a hypothesis that Dark Matter is not a WIMP, but maybe is a deformation of space-time by which the curvature of space-time ALONE is the cause of the gravitational effect. Gravity is the consequence of the curvature of space-time. It may be possible that the structure of space-time itself could be warped without the presence of mass. Space-time has been shown to react like a fabric by warping, twisting, and propagating independent of mass. These properties have been proven with observations of gravitational lensing, frame dragging, and now gravitational waves. Fabrics can be stretched, pressured, and/or heated to the point of deformation. Such extreme conditions were all present during inflation, so it is plausible that space-time’s elastic nature could have hit its yield point and permanently deformed. Therefore, if gravity is the consequence of the warping of space-time, and fabrics can be permanently deformed, then a deformation could create a gravitational effect independent of mass. DM could be a microscopic imprints or stretch marks like black holes with no mass at the center, but they wouldn't lose their strength via Hawking Radiation because the warped geodesics/fabric is fixed.

Prediction: Spacetime's elastic property hits a yield point, so only that part of geodesic's "stretch marks" would remain after inflation stopped. These steep gravitational wells would not follow the inverse square law.
They would be steep tiny gravity wells that produce gravitational effects with nothing in them to detect.

[ndclasscanadian]

Can a black hole displace space and time like a person getting into a bathtub?