LIGO team member Joshua Smith explains gravitational waves discovery with Tomorrow Daily
Some huge science news this week, some of Einstein's oldest.
Unproven theories have been proven true, but it's pretty dense stuff, so we got an awesome guest to come help us unpack this news today.
We do, from Cal State University Fullerton, we have the director of Gravitational Wave Physics and Astronomy Center, Joshua Smith, hello.
Can we call you Josh, [UNKNOWN] for Josh?
Please, Call me Josh.
Josh, this is as Jeff said, very dense stuff, but again proving some theories that Einstein had about ripples in space time that are over 100 years old.
Yeah, this is the Theory of Relativity.
The theory we know of general relativity and That's right So, a hundred years ago-
A hundred years ago, Einstein told us that gravity works differently than Newton said.
So, Newton said that you would have a force between two objects based on their masses.
And Einstein said gravity works by curving space and time.
But with a curved space-time, he said that if you had masses that accelerated, kind of moved around like this, they should also make ripples
In space and time that would carry the information out as you travel.
Yeah, but we've never seen them before.
He said theoretically it should happen.
We've never seen them before, and the reason we've never seen them before is because they're so small, right?
Absolutely, so in Einstein's original paper, he said if you put in the equation and you calculate what the amplitude is, it's practically vanishing for any numbers that you put in.
But at the time 100 years ago Einstein didn't think about two black holes going around each other in space.
He was, 100 years ago that wasn't a known system.
So basically the idea is that there is stuff that has mass in the universe.
That mass causes ripples in gravity.
And because black holes have so much mass
We're actually able to measure their waves, their gravitational waves.
And it made very tiny, tiny movements.
So, actually, the black holes have so much mass and they're going around each other so fast, so they're going around each other so fast it's a fraction of the speed of light.
The black holes that we saw were a billion light-years away.
So if you were there the waves would be really, really strong.
We could surf them.
Yeah, get on a surfboard which answers one of our viewer questions.
They said can you in fact.
Surf on gravitational waves?
If you were there a billion years ago?
I think being, a billion years ago being close enough to surf on the gravitational waves from the black holes would be very bad for your health.
You could do it though, but you could do it and then die.
Kinda like actual surfing here with the sharks-
Yeah, that's true.
So gravitational waves is actually space time changing, so things are actually moving closer to you or further away from you?
The space and time between objects changes as the gravitation waves passes and that's how we measure it, so we built a giant.
It's called interferometer, gravitation wave observatory.
That looks at the difference between distances and mirrors, with laser beams.
So it makes a very accurate measurement of that distance, and the distance changes as a wave passes by.
But the change is so tiny on Earth, that it took a hundred years to develop the technology to be able to make that measurement.
To detect that, okay.
We're talking like the size of what?
Like a molecule.
It's like the diameter of a hydrogen atom, right?
Like is it
A thousandth of the diameter of a proton more like it, so.
So we're talking about 10 to the minus 19 meters, which seems like an impossible number.
But we've worked on lots of areas of technology to make that possible and it is possible.
How do we measure that small of a distance a billion light years away.
So using the lasers and the mirrors we make that accurate measurement
And there are a lot of things you have to overcome.
One of them is, just the mirrors themselves have atoms in them that jiggle around, atoms and molecules.
It turns out, if you try to make a measurement, with a very small amount of laser light in a very small area, the atoms will jiggle too much.
So you have to make a measurement with a big laser spot, to average over the statistical jiggling of them so they average to zero So you can measure the true-
I have atoms that jiggle too.
Try to relate, I understand.
We all do.
So one of the things that I thought was really interesting was one of the videos online, they sort of talked about how they actually attempted to measure for this back in the 60s and 70s and did not have the technology, and also built small.
Like you were saying, it didn't quite work.
So Ligo now is
Two different locations.
And the actual length of each, cuz it's a perpendicular series of tunnels, right.
And so these perpendicular series of tunnels are five kilometers, two and a half miles.
Two and a half miles long.
So we're looking at a two and a half mile long tube for each of these lasers, two lasers per lego.
Per observatory, to-
And that's for redundancy, right?
To check, yeah.
Well so, the two observatories is for redundancy to check each other, because you wouldn't want a local disturbance to be measured at one, and then not have a way to tell that it was local.
So by having two widely separated detectors, and by the way, we wanna build more.
We want to build one in India.
There's one coming online in Italy, and there's one in Germany.
Detection on widely separated fronts, you can tell that it wasn't a local disturbance.
Right, that it wasn't an anomaly or something, you can confirm that this actually is a definable measurement that happened in two different places.
Okay, go ahead.
And another thing we can do is we can match what we measure.
To the predictions using Einstein's equations.
So you can use Einstein's equations to solve what you think the system should look like, in this case 2 black holes that are 30 times the mass of the Sun going around each other.
And that gives a waveform prediction for what you should expect.
And you can match that against what you really see to gain confidence that what you really saw came in fact from that kind of system.
I see, okay.
What does this mean?
This means that Einstein was right, and this is sort of the last bit of his theory that hadn't been observationally proven, right?
So it is challenging to test different aspects
[UNKNOWN] Mind science theory and I'm not sure that you can say that this is the last bit that's been proven because what we'll do is we'll continue to test the theory with more and more accuracy and look for any small deviations that we see between his theory of gravity of what we actually observe.
For scientists it's exciting if you can see the oceans.
Because that means something is wrong.
And maybe we can get a deeper understanding.
By figuring that out.
Everybody wants Einstein to be wrong.
I know but you know what?
That guy is always right.
A 100 years, he is right.
Yeah it's very.
It's so unbelievable.
It is an amazing thing.
Does this have practical application going
Before for scientists?
So one thing that I think is pretty interesting is that this opens up a new way to observe the universe.
Everything that we've seen about the universe so far, the majority of it has been through light.
And light has different forms.
So you can have radio and x-rays and visible light and gamma rays.
This is an entirely different spectrum than that.
This is measuring gravity from gravity.
Not from electrons jiggling around but from masses moving.
So this opens up a totally new way to look at the universe and we expect to see not only Poles, but things like neutron stars or exploding stars or possibly some remnants of The Big Bang.
So that's one thing that it gives us but another is technology.
So in order to solve a lot of the problems, like quantum mechanics and things like that that we needed to overcome, we had to build technology that's gonna to push forward in areas of technology That aren't related to gravitational waves.
And that's a give and take because we also use the technology that's developed in other areas to refine our instruments.
You compensate for my jiggling adams.
Well, that's really the goal here.
[UNKNOWN] Jiggling adams.
So, on of the, we have a couple questions from viewers, and also, I just really quickly want to thank John Strickland from Forward Thinking.
He sent us a really nice primer on gravitational waves he's working on a two part episode about gravitational waves, I highly recommend you check that out when it's released
And thank you again John for helping us learn a little bit more before we got to talk to Josh.
Ok so Stefan asked, what unit of measurement (or medium) do we measure gravitational wave with?
Gravitational waves have an amplitude.
The amplitude of the wave is something that's called strain.
And strain is the amount of stretch that you get for a given length.
So the reason that the arms of [UNKNOWN] are so long is because that means the longer you make the arm, the longer the motion happens because of the strain.
It's a fractional change, so if you make the arms really long you get a bigger change.
So the amplitude of gravitational waves is in strain and then I guess you can say we measure it in dimensions of meters in our instrument.
10 to the negative 11.
10 to the minus 19.
You can also say we measure it as light because the instrument
Is set up so it's kinda a trap for gravitational waves.
They come in and if they move the arms back and forth it causes a little bit of light to come out of what we call the dark port that's normally dark, and that little bit of light encodes the [UNKNOWN] signal as photons.
And that's what we measure.
The admiral Akbar of gravitation waves.
It's a trap [UNKNOWN] as they come in
Here Arnold also asked us, one of viewers, is it possible to harness the waves for energy?
FTL propulsion or time travel-esque applications?
So let's talk a little bit with that being asked, Let's talk a little bit about the fact that, as I understand it.
And correct me if I'm wrong.
This is sort of like getting a new sense.
So let's say we have these five senses, and all of a sudden, we get a new sense.
And we say, okay.
I don't really necessarily know exactly what this is going to be used before.
But I know that I'll never be the same again.
That sort of, kind of the
You put that so beautifully I don't know how to improve on it.
Okay, well good.
Okay, I'm glad.
Time travel, can we do it?
That's the question.
So that being said there was no specific application that you were looking for just specifically to confirm gravitational waves and from here
Go forward to find potential uses for the knowledge of gravitational wave.
Yeah, so I think-
Jeff just really wants a time machine.
I mean can you blame me?
No, I can't.
I think the initial application is just that we can see the universe in this new way and we can do astronomy.
There is the technological benefits for building something like this, but I think having opened up a new sense For humanity, is a nice application on its own.
So, I don't know about time travel, Jeff.
No, not that much?
Not sure if we're gonna get you there from this.
But I do think as Kip Thorne said, this allows us to understand Eisenstein's Theory a little bit better.
And Eisenstein Theory is probably a good place to start in your garage as you build your time machine.
Well, the reason that I know that this
Isn't going to be the thing that gets us there is because future me just didn't show up to give me a high five.
Or did he?
Maybe you are future you, and you're just putting up a front.
I don't know.
I gotta say if so I've aged well.
You have aged quite well.
Let me see if we have any other.
We had a lot of questions come in.
Well, it's a very dense topic.
You know I was all excited.
Fan of science.
You read the articles that come out.
You see the big headlines.
we did it we discovered them, and you go okay well but, what does mean.
And how does is that accomplished.
So John asked specifically how is the difference from the data we first though the bicep two telescope uncovered back in 2014 and could gravitational
Astronomy tells more about he origins of the universe, which you did mention.
You said potentially maybe.
Yeah, I said he's a smart guy.
He helped us out.
That's a great question.
So the original bicep two results, we're looking at We're looking at twisting that was imparted in spacetime from the birth of the universe in the Big Bang.
And so the idea was that there were gravitational waves at the Big Bang, and they imparted some twisting on spacetime.
And as that spacetime grew it stretched out, and we could look for that with our telescopes at the South Pole.
I'm not involved in that project but that's my understanding.
Our project measured directly gravitational waves coming from a source of two black holes, and we expect that we're gonna measure other things like exploding stars, or neutron stars, so I think the difference is that.
For one thing, we're in a different frequency range.
So we're in a frequency range where things are moving around quite fast, and what we hope that we've done is opened up a field of gravitational wave astronomy where other projects will join.
Including ones like something called pulsar timing where they look at spinning pulsars, a type of star, they look at those and they use those as the timing to measure the gravitational waves that pass between them.
And that's a much lower frequency.
And so all of those frequencies together bicep to In related projects, impulse our timing and enter parameters in space for example called LISA and LIGO will span the whole spectrum like we do with light.
So we can see a lot
You could really see a lot of different things.
How do you know where to look?
How did you guys know where to find the two black holes?
So our instruments
Act a little bit more like a microphone than they do a telescope.
They're arranged on the earth and the waves kind of bathe them.
The earth doesn't block waves so they come through both instruments and from the timing and a little bit more information we can tell roughly where they came from.
So this came from the southern sky, but we didn't have to point at it We can tell by reconstructing the waves as they hit them.
So it's a little bit like a
That's what's so different about gravitational waves right?
Is that they don't impact things.
They just move through things, right?
Well there's a duality.
There's this wave particle duality as well.
So We measure them clearly as a wave, but there is an associated particle we think called the graviton.
So we don't know.
Similar to light.
Also the name of my super awesome band that I'm starting today.
Graviton rocks by the way.
That's the name of my new band.
Let's lastly talk a little bit about Cal State Fullerton's role in this.
You guys did some very interesting things to be able to help everybody visualize exactly what this discovery is.
So I'm really proud of Cal State Fullerton's role.
We have undergraduate students who are learning relativity at the same time that they're doing some of this work.
And we have graduate students and three professors And we, yeah, so our student's created visualization simulations of the two black poles.
We were among the first, actually the first to look at the exact parameters of the black holes that we detected on super computers at Cal state Fullerton ran simulations to see the black holes merge and then created visualizations along with collaborators in simulating extreme space time collaborations, another cool thing.
That sounds awesome, another cool thing, yeah, anything that I can be a part of that I would be into.
And we had the privilege also to be very closely involved with writing the paper that announced the discovery.
You were one of the lead editors on it, one of the six editors on the paper, right?
And so that was a great privilege.
Because 1,000 people were authors on the paper.
And there was a lot of input.
And a lot of the words and the thoughts and the measurements came from people across the collaboration.
And we tried to work to make a you know a legible, compelling, cohesive story out of that.
Hell of an email change.
You're absolutely right there.
This is awesome.
Thank you so much.
I think it shed some light.
You know in any form the light wants to take.
It shed light and waves on this very dense topic.
It's so big and so
important that it's hard for us sometimes I think as
As people just kind of reading the news sorta wrap our brains around.
It's sorta that thing where you really start thinking about the universe.
And then your head hurts after a while.
I really love that you came down here and talked to us a little bit about it.
Thank you so much.
If anybody wanted to learn more about the project, what would they search for on Google?
Well, gravitational waves will get you a lot of the way.
You can go to ligo.org where a lot of our scientific-
L I G O.
L I G O.org.
And Ligo was it's name o.
And a lot of our scientific results are posted there, and we work hard to make science summaries of all of our scientific papers.
So that people can access them, the public can access them, and if people still have questions after that, we work really hard to answer any emails that we get about them, and we have kind of a whole troop of people answering emails right now.
Man it was awesome.
Awesome yeah, Joshua Smith
Thank you so much for being here.
We've got more Tomorrow Daily coming at you.
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