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Scichat: Gravitational Waves, Black Holes, and Time Travel: A Cosmic Conversation with Dr. Isobel Ramero-Shaw

• Jason Zackowski

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Ever wondered about the intriguing world of gravitational waves, black holes, and time travel? Get ready to stretch your mind as we chat with the spirited Dr. Isobel Ramero-Shaw, an accomplished physicist whose tenacity led her to the far reaches of gravitational wave astrophysics. From her path from literature to mathematics to astrophysics, to the rippling effect of gravitational waves, embark with us on this illuminating journey.

The episode unfolds as we venture into the mysterious realm of black holes. What if you were to fall into a black hole? The Doc brings the science behind the film Interstellar under the microscope, analyzing its depiction of black holes and their impact on time and space. She also delves into the tantalizing concept of time travel via black holes and wormholes, and the challenging study of these celestial bodies.

But that's not all! We take an unexpected detour to discover the charming world of giant African land snails, each with their unique personalities. We also explore a riveting science fiction narrative involving conversations with aliens on a neutron star and ponder the possibility of a black hole lurking within our solar system.

Dr. Isobel on Twitter:
https://twitter.com/astrobel_rs

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Speaker 1:

Hello science enthusiasts. My name is Jason Zikowski. I'm the dog dad of Bunsen Beaker the science dogs on social media.

Speaker 2:

My co-host is Hi there, I'm Chris Zikowski and I am the dog mum to Bunsen Beaker and the cat mum to Ginger.

Speaker 1:

Every week we bring an amazing expert to enthrall you with their area of knowledge, and we are thrilled to welcome to SciChat Dr Isabel Ramiro Shah. How are you doing tonight, doc?

Speaker 3:

Hi, yes, I'm doing really well, thank you, Hope you're all well as well.

Speaker 1:

We are good. We are good. Now, folks, you could help us out by tweeting out the space. It's a busy, doc. It looks like there's lots of people having audio shows tonight. We'll get some more ears in here listening. We'll pick up people as we go. One of the first questions we ask our guests just to quickly share is a little bit about their training in science. Doc, would you be able to do that?

Speaker 3:

Yes, of course. So I studied physics at the University of Birmingham in the UK and my undergraduate degree also included like an integrated master's year. So I graduated from that degree with an undergraduate master's and I then flew to literally the other side of the world to do my PhD in gravitational wave astrophysics in Melbourne, australia, and Monash University, which is where I was until early 2022 when I graduated, and I stayed working at Monash for a little bit, for a few months, before moving back here to the UK, where I am now, and to take up my current position as a Herschel Smith research fellow at the University of Cambridge.

Speaker 1:

When you were young, were you all into math and physics. Like was that something? You were calculating how far and fast things were falling.

Speaker 3:

As a small child, oh no, I wish, I wish I. Actually I really was not a mathy child. That was something that I really had to kind of encourage my brain to be wanting to do. I was much more into reading, I did like science and I was very curious about lots of things, but I definitely was much more of a words person than a numbers person as a child.

Speaker 1:

So how did you get into like the math and physics that you're doing right now, like what changed for you? That's fascinating.

Speaker 3:

Yeah Well, so when I was growing up, I was as I was saying, I was really into reading. I was also really into kind of exploring and arts and lots of different things, and this kind of continued as I was going through school and I chose to do my A levels in fine arts, english literature and physics, which it turns out are not a very good combination of things to do if you want to do any of those things further at university. And basically in the end it just happened that the worst result of all of my exams was physics and I kind of that. That annoys me. I wanted to prove that I actually could do physics, so I ended up going and doing before my undergraduate masters, I did a foundation year in science which included a lot of training in maths for physics, basically Okay, and I just had to convince myself that that was something that I was good at in order to actually go ahead and study physics further.

Speaker 1:

So your life trajectory was because you were stubborn.

Speaker 3:

Yeah, pretty much that's. That's how I would describe it, my goodness. That's that is wild doc Now, that is a big hill to die on.

Speaker 1:

Well, I don't know the things I was not good at. I did not pursue in post-secondary at all. I was like you know, I'm not so good at that and people are telling me so I'm going to do some other stuff. That sounds sensible, yeah.

Speaker 3:

So that's, resistance.

Speaker 1:

Well, well, get a bit, a bit, yeah, and one of the wild things is like I introduced you. As you know, you have a doctorate and we'll get right to it, because you study gravitational waves now and I swear, every week there's something new coming out about gravitational waves. We spoke actually, for spoiler alert, the doc is a guest on the science podcast, so you'll get more in depth into this Maybe if you'll listen to that episode. It's kind of not out yet, but I was wondering if you could tell us a little bit about, like, what are gravitational waves? What are they?

Speaker 3:

Yeah, sure. So gravitational waves are rippling modulations in a gravitational field. So you know that gravity pulls us to the surface of the earth, right, and the earth is kept in its orbit around the sun by gravity as well. So if you imagine the universe as a big sheet of stretchy plastic and imagine that you're putting a bowling ball on that sheet so that it stretches and pulls the sheet into a dent around the bowling ball, this is kind of similar to how the fabric of space time responds to a large mass like the sun, except that in this example the plastic sheet is two dimensional, whereas the fabric of space time is four dimensional.

Speaker 3:

But if you just forget about those extra dimensions for a second we can go back to the bowling ball making a dent in the plastic sheet. And then if you take a ping pong ball and roll it around the bowling ball, that's a bit like the earth on its orbit around the sun. And if you zoom in on the ping pong ball, that's also making a much shallower dent in the plastic sheet around itself and grains of dust on that plastic sheet are falling towards it as a result and that's like us being pulled towards the earth. So Einstein summed this up by saying that matter tells space time how to bend and space time tells matter how to move. But instead of the bowling ball and the ping pong ball.

Speaker 3:

Now if we imagine taking two very, very heavy and dense lead balls and then making them roll around each other on the plastic sheet, so they will both deform the plastic sheet significantly as they roll around, and this will also cause ripples in that sheet that propagate away from the two orbiting bodies, if you will. So if you took another two light bodies, for example two grains of dust, and put them on the sheet further away from the orbiting dense lead balls, then the distance between those two grains of dust will change as the ripples in the plastic sheet pass through that region of the plastic sheet that's underneath them. So this is essentially how gravitational waves happen, except instead of lead balls we have black holes, and instead of a two dimensional plastic sheet we have the four dimensional fabric of space time. And so gravitational waves were predicted by Einstein in 1995. But it took about 100 years for the technology for detection to catch up with those predictions, and the first gravitational wave detection was not made until 2015,. So 100 years later.

Speaker 1:

So he predicted them in the 1800s.

Speaker 3:

No, in the 1900s oh 1900s.

Speaker 1:

I'm sorry, emma spoke yeah.

Speaker 3:

Oh sorry, yeah, yeah, in 1915. Yeah 1915. Yeah, yeah, that's what I said, that's what I meant to say.

Speaker 1:

And he was just doing like a thought experiment, like in his brain, like was this based on calculations? Like how?

Speaker 3:

Yes, yeah, oh, okay, he was thinking about gravity and how gravity should be working. So this is when he was coming up with his theory of general relativity.

Speaker 1:

So I've seen that demonstration before, that things that have a lot of gravity, like a star. I think one I show my students is a professor. He has like a big sheet of lycra and it's over over top of like I don't know some kind of thing. So when you put something on it it bends down. I don't know, like it's stretched over a drum or something like that.

Speaker 3:

Yeah, yeah, that's the common example.

Speaker 1:

Yeah, is that literally what gravity is doing? It's like creating this well in the stuff that is all around us, like space time.

Speaker 3:

Is that a good analogy, but it's just in four dimensions rather than two dimensions. So actually sometimes I like to imagine, instead of putting a ball on a sheet. I imagine like a spider at the center of a really dense web, like pulling all the strands towards itself.

Speaker 1:

Okay.

Speaker 3:

But obviously that doesn't. That also doesn't work because the spider itself is also affected by gravity. So it's not 100% accurate and also that would only be in three dimensions, but it kind of gives you an idea of how it would look in higher dimensional space, I think.

Speaker 1:

Doc, I feel like I'm Marty McFly and you're like, you're just not thinking fourth dimensionally, marty, every time you say that.

Speaker 3:

Yeah, it is very difficult to get your head wrapped around four dimensions. So it's it is much easier to think about the plastic sheet.

Speaker 1:

Okay, so gravitational waves are made like are they made from everything? Or they made from like really, really wicked dense stuff going around each other?

Speaker 3:

Yeah, so they are kind of made from all asymmetric accelerations of mass, but we don't really expect to be able to detect them from anything unless it is very, very dense and very, very massive. So the ones that we are actually detecting at the moment are typically coming from black holes that are spiraling around each other, or sometimes other very compact objects like neutron stars.

Speaker 2:

And how do we detect them then? So we detect them?

Speaker 3:

Yes, we detect them using enormous interferometers. So there are two in the US, in Hanford and in Livingston, which are the LIGO detectors. Then there is a third one in Italy, near Pisa, called Virgo, and there's another one in Japan called Kagura, and they are essentially big L shapes. And the L shapes have two arms and inside the arms are vacuums and at the kind of vertex of the L is a mirror that splits a beam of light, of laser light, and at the ends of the two arms are test masses or mirrors that reflect back that laser light. And the interferometers work such that if that light beam is split down those two arms and then reflected off the test masses at the end and comes back together at the vertex of the L and recombines, if the distance is between the mirror that's splitting the lights and the mirror at the end of each arm, if that distance changes due to the passage of a gravitational wave, then the interference pattern of the light that's recombined will also change and we can measure the passing gravitational wave via that interference pattern.

Speaker 4:

Wow.

Speaker 1:

So the gravitational wave comes along and it gibles up the distance.

Speaker 3:

Yeah, it stretches the distance between. It stretches and squeezes the distance between the beam splitting mirror and the test mass mirror at the end of the tube.

Speaker 1:

And we don't feel this like when a gravitational wave hits Earth. We don't go like like we're felt. You know how, when you're going, when an elevator drops to and you're like, whoa, that was a gravitational wave.

Speaker 3:

No, we don't feel it, because the amplitude of the oscillation is so very small, so that the first gravitational wave that was detected when it passed through this region of the universe and it was changing distances and stuff, it only changed the distance between the Earth and the Sun by the same width as a human hair. So this isn't the kind of change that we can actually feel ourselves. We need these incredibly sensitive instruments to be able to do this.

Speaker 2:

Okay, and are they coming in? I guess waves like in the ocean, where it's periodic, where the waves just keep coming in, or are they few and far between?

Speaker 3:

That is a very good question. It depends on the source. So for these black holes I'm talking about, where they spiral around each other, they eventually fall together and they merge and this causes a kind of transient signal. So this is just something that happens once. So you'll only detect one gravitational wave or one gravitational wave signal from a merger event like that. But then you might also have something called the background of gravitational waves, which would be more like a kind of continually rolling sea of gravitational waves, and that would be something that would be arising from lots and lots of different merger events so ones that we can't resolve individually, that are all going on all around us all the time, or from other events that are not black holes spiraling around each other. For example, if you have a neutral star that is rotating and has a mountain on it, then that can also cause gravitational waves and that would cause a continuous gravitational wave. That would be more like this kind of continually rolling sea.

Speaker 1:

So if we make an analogy, like somebody has, like, hooked a rock in the middle of a lake, the teeny tiny ripples at the shoreline. That's what you're measuring. They're very, very, very, very small, but they did come from something relatively large.

Speaker 3:

Yes, yeah, exactly. It turns out that space time is very stiff, so it's difficult to make it oscillate a lot.

Speaker 1:

Okay, I have another question. Do these gravitational waves just go on forever, like if you shot a bullet in outer space and it never hit anything and it never slowed down. It would go forever, like it would just go, go, go.

Speaker 3:

Yeah, you're right about that. So gravitational waves don't interact very strongly with anything at all, actually, so they will just kind of keep going. They're not impeded very much by anything, and this actually means that. So we had an event in 2017, which was the collision of two neutral stars and that released electromagnetic radiation as well as gravitational radiation, and the gravitational radiation reached us earlier than the electromagnetic radiation, even though gravitational waves and lights travel at the same speed, because lights is impeded by things in between us and the event that's happening and it has to follow. You know, it has to. It has to go towards us, but then it goes around other objects and it goes through gas and stuff, so it ends up being a bit slower than the gravitational waves. That's not to say that they move faster than light. They don't move faster than light.

Speaker 1:

Right, okay, I was, I was, I was all excited. The light can be blocked. I was all excited for a second that they move faster than light, and then now we've okay.

Speaker 3:

No, no, only if something gets in the way of the light.

Speaker 1:

Yeah, Okay, so just like a honey badger, gravitational waves, just don't care, they just go.

Speaker 3:

Pretty much, yeah, that's. That's exactly right yeah.

Speaker 1:

Okay, so I have an awkward question, but I'm sure it's one that you've answered millions of times why? Why is this a thing we should care about, like I hear about it all the time? It is incredible that we're detecting like neutron stars or black holes colliding. How does that, how does it help you as a space scientist?

Speaker 3:

Yeah.

Speaker 3:

So I like to motivate this by saying, like if you were going out into into a forest or something and you only had a torch and you had earmuffs on, detecting gravitational waves is like taking those earmuffs off. So you're going into the forest and now you have an extra sense to help you make sense of your surroundings. And I think this is important because, as humans, we've always been going out and exploring. We've always been going out and looking over the horizon and wondering what's next and what's out there and trying to understand things about our surroundings and about our universe in general. And being able to detect gravitational waves gives us a whole new way to discover things about the universe.

Speaker 3:

And this is really important for understanding our place in the universe. And, yeah, just for making sense of what's going on around us, what's going on with the systems that we see around us. So we see all of these stars in space and we look up at night. A lot of those stars are going to end up becoming black coals or neutral stars. So understanding this extra step of their evolution is very important for understanding in general what's going on in the universe around us.

Speaker 1:

I love it. If you're just tuning in, we have Dr Isabel Ramiro Shaw, who is an expert in gravitational waves, so very, very cool. I love that answer. Chris gave you a little 100. Chris, what spoke to you the most about that?

Speaker 2:

Just that, as humans are curious and we always want to find out more about what's around the corner, and I love that, and so this is just one way to expand our understanding into what has not been known, and as our instruments get better and more precise, we're able to detect more things, which is fantastic.

Speaker 1:

Like aliens Like aliens. Do you? Before we move to my next kind of like section of the questions here, Doc, what do you have? Do you have some bets on what they're going to help us discover, or is it? Or is it just so new? It's not something that we know Like, what we don't know is what we don't know right now.

Speaker 3:

Well, yeah, there's an element of both of those things.

Speaker 3:

I think what's exciting is that with every single observing run of the detectors, we're detecting new things.

Speaker 3:

So the first observing run which yielded detections in 2015, ended up revealing to us that the pairs of black holes the black holes that we were seeing in these gravitational wave events had quite different masses than we were expecting. We were expecting to see mostly black holes that were around 10 times the mass of the sun, and it turns out that most of the things we're detecting are around 30 times the mass of the sun, which is surprising and interesting and means that some of our understanding or some of our assumptions about the universe were slightly off. Then, with the next observing run, we ended up seeing this pair of neutral stars prashing together, which had the electromagnetic count part, which also enabled us to do a lot of other studies of interesting physics and things, and with the observing run after that, we saw pairs of black holes that were paired up with a neutron star. So we saw neutron stars and black holes crashing into each other as well, and this also revealed more things about our physical assumptions and about our models of stellar evolution and various things like that.

Speaker 3:

So there are lots and lots of things that we are discovering with every single new observing run, and I think it's just really exciting because, as you say, this is an incredibly new field, so lots of the things that we're detecting are completely surprises to us. So there are lots of other things that we can hope to detect in kind of the near future, like gravitational waves from supernovae, because supernovae should also produce gravitational waves because they're an asymmetric acceleration of mass. Yeah, so that would be a really cool thing to be able to detect, because that would also tell us more about the physics of supernovae and things like that.

Speaker 1:

You know, those stars that go supernova, they're just, they're drama queens. Yeah, I they just, they just want let everybody know how upset they are. I tell you, yeah.

Speaker 3:

Well, wouldn't you, if you, if you were exploding, would you not want to tell everyone?

Speaker 1:

I guess, I guess. Oh, my goodness, I love your analogy of going into the forest with earmuffs on and a flashlight because, like you could be in the forest and you, it's dark and you shine your flashlight on like a creature and your brain just has to make up like oh, I wonder what sound it makes, right?

Speaker 2:

And you're like.

Speaker 1:

I think, I think you look, this little creature goes and you're like, that's the sound and all the other scientists are like, yeah, I think that little creature goes, and then you take the earmuffs off and the creature goes.

Speaker 4:

Right.

Speaker 1:

Like it's just so completely off what you thought, and that's that's the cool thing about having extra ways to detect science. I love it, yeah, yeah, I agree.

Speaker 3:

I would say that the the actual predictions for what these gravitational waves would look like, which come from Einstein's predictions, from Einstein's kind of mathematical description of gravitational waves, have so far turned out to be exactly accurate. What so the way we thought that these gravitational waves would sound? They might have been, you know, a bit louder than we thought that they would be, but they are otherwise exactly consistent with his description of general relativity so far. So no deviations from general relativity have been detected at this point.

Speaker 1:

How did he get so much stuff right back then?

Speaker 3:

Yeah, it's amazing how Like every we're just still doing this guy's homework.

Speaker 1:

Like he's like yeah, guess what, guys, in a hundred years you're going to have a whole bunch of homework for another century. Yeah Well.

Speaker 3:

I actually never thought that we would be able to detect gravitational waves, because he worked out that the magnitude of them, that the amplitude, would be so small which is what I was saying earlier about about space time being really stiff so he just thought that they were kind of like a fun mathematical thing that would never actually be observed, which is, yeah, it's pretty cool how the reality of science changes like that.

Speaker 1:

Did one of the LIGO scientists like after it was detected? Lego like ha ha, suck it, einstein. We detected it. Like how You're wrong.

Speaker 3:

Yeah, that's it. We're all just out to spy Einstein, okay.

Speaker 1:

I was wondering, doc, if we could talk about black holes, because I love black holes and just the more I know, learn about them. They just blow my mind and I know, like you, have to know a bit about them, obviously for gravitational waves. Are there some things that are taught or are told about black holes that are just wrong and we just keep getting it wrong, like could you set the record straight about maybe some myths?

Speaker 3:

Yeah.

Speaker 3:

So the first thing that I wanted to talk about is spaghettification, which is a real thing, it's a real word and it's a real danger if you get too close to a black hole. But actually it's worse for smaller black holes, it's not worse for more massive black holes, which is possibly against the kind of common assumption. So spaghettification is what happens when there's a big difference in the gravity that you feel at one end of your body versus the other, which means that you stretch out until you're really really long and thin because your feet are being accelerated towards the black hole while your head is not being so much accelerated towards the black hole. But the reason it's going to be a lot worse for smaller black holes than for bigger ones is because the gravitational gradient at the event horizon of a smaller black hole or a less massive black hole is steeper and kind of more locally varied than for a more massive black hole. So the point of no return for a black hole is just short child radius or the event horizon.

Speaker 3:

And if you know about the recent amazing photos from the event horizon telescope of the black hole M87 and also Sagittarius, a star, the second of which is the black hole at the center of our galaxy. So if you see in these photos, you will see that they look like kind of rings of light, and this is caused by extremely fast moving matter orbiting the black hole at the event horizon. Just before crossing the event horizon, and because it's orbiting so fast it heats up and releases electromagnetic radiation. So these rings and these photos mark out where the event horizon is and beyond that nothing can escape, not even light, which is the fastest moving thing in the universe. It sucks, yes, yeah, exactly.

Speaker 3:

The event horizon, as I was saying, is larger for a more massive black hole and the gravitational gradient sloping down towards the singularity at the center is shallower. So if you were crossing the event horizon of a really massive black hole, you'd probably not feel much physically. Obviously, emotionally you would feel an impending sense of doom and fear, but physically you wouldn't feel much, whereas with a less massive black hole with a smaller event horizon, if you were going towards it, the gravitational gradient between your head and your feet would be steeper, so that would mean that you would get a spaghettified. So that's myth number one. Be more wary of smaller black holes than massive black holes.

Speaker 1:

All right, we'll make sure pro tip everybody when approaching a black hole. Watch out for the little guys.

Speaker 3:

Yes, exactly. Ok. I also have another misconception, which is that if the sun turned into a black hole right now, what do you think would happen? If the sun turned into a black hole right now, do you think we would go accelerating towards it?

Speaker 1:

If the sun turned into a black hole, yeah Well, I don't know. Wouldn't it just go pitch black instantly, like seven minutes later?

Speaker 3:

Yes, Around seven to eight minutes later we would go pitch black. That would be very bad. Obviously, if the sun turned into a black hole, we would be in trouble, but our orbit would stay exactly the same.

Speaker 1:

Oh, I was going to say Tesla shares would just go right to the toilet. Ok, never mind.

Speaker 3:

Yeah, we should all hope that this doesn't happen for Elon's sake, but yeah, but so our orbit would stay exactly the same. We wouldn't go accelerating towards the sun, because of the distance that we're at from the sun, the effect of gravity would still be exactly the same. So we would obviously get very cold and it would be really dark and we would have a lot of problems, but we wouldn't be getting spaghettified. So that's at least something.

Speaker 1:

At least we're not spaghettified. We're just freezing and have no sun ever again.

Speaker 3:

It's not so bad, ok, ok.

Speaker 1:

And black holes don't suck. Right Like that's a joke I made. They don't suck because that's a myth too. Right Like they don't, not like they have a tractor beam on you.

Speaker 3:

Yeah, they're not malicious, they're just existing and gravity is just really really strong around them. So, yeah, as long as you don't get too close, I guess they're kind of like dangerous animals Like, as long as you don't go messing with them, they're not going to come and get you.

Speaker 1:

They're like a moose. You cross that event horizon. That's it for you.

Speaker 3:

I don't know. I've never interacted with a moose.

Speaker 1:

Oh, that's good, because you'd be dead, all right. Oh, okay, sarah, go ahead.

Speaker 4:

Hi, thank you. This is such a good conversation. You know there's a lot of myths about black holes and a lot of you know every space movie. I'm sure you've watched some of them. Have you ever seen anyone, any one of these movies, that was even remotely accurate?

Speaker 3:

Yeah, so the movie Interstellar is actually very scientifically accurate. Yeah, yeah. So the reason that that one was really scientifically accurate is because the science advisor on that movie was Professor Kip Thorne, who was actually one of the three winners of the 2017 Nobel Prize in Physics for the first detection of gravitational waves oh, wow, yeah. And apparently he was very, very strict with Christopher Nolan about what could and couldn't go into that movie. So I watched an interview between them where Christopher Nolan was saying that he really wanted at some point, for the characters to be travelling faster than the speed of light and Kip Thorne was like absolutely not, can't happen, won't happen. We cannot have this in the movie. So Kip Thorne has written a book about the science of Interstellar and everything and, yeah, it is actually very scientifically accurate. So, for example, the view of the black hole which is called Gargantua, I think.

Speaker 1:

I love that name.

Speaker 3:

Yeah, it's pretty cool, but it was pretty. So. They predicted an image of that, like what it would look like from the outside was predicted before the event. Horizon Telescope had taken photographs of M87 and Sagittarius A star, but it's actually pretty similar in appearance. If you kind of compare the two, obviously the one in Interstellar is much more detailed, but yeah, they have pretty similar appearances and that's because the view of that black hole in Interstellar was predicted using Einstein's equations and just kind of doing light tracing around black hole of that size. So that's pretty cool.

Speaker 3:

Also, time, as it's depicted in that movie, definitely slows down as space-time is stretched by mass. So in that movie the characters go to a planet that's orbiting around a black hole and while they're on that planet their passage of time is like one hour or something, and then the passage of time back on Earth is like seven years. And this is because they're in the really, really strong gravity. And this also happens in more mundane settings as well as for black holes. So, for example, when the clocks on satellites that are used for GPS are programmed, they have to take into account that the gravitational field on the surface of the Earth is different than the gravitational field at the location of the satellite. So time on Earth actually slows by one second every 100 years due to the effect of the Earth's gravity, and this has to be accounted for when you're programming those satellites.

Speaker 3:

Like thinking about other bits of Interstellar, there are bits that push the boundaries of science. So I don't want to do too many spoilers. But there are some points when the main character is like moving through time and manipulating gravity himself and things, and this is kind of taking a liberty with the science. But we actually don't know what a human would experience if they fell into a black hole. So there is a fair amount of room for artistic license at this point. And Kip Thorne said like some of the science in the movie is truth and some of it is speculation, and it kind of all works within the boundaries of what we currently know. But because we actually know so little about how physics works at the singularity or potentially whether there are like multiple singularities or how quantum gravity works and stuff, there is a lot of room for creativity there.

Speaker 1:

Sarah, back to you, go ahead.

Speaker 4:

You said well, first about the movie. If somebody were to get a person, were to get that close or go into a black hole, you're saying that time for them would almost stand still. But time on earth would pass much faster than a person in a black hole.

Speaker 3:

Yeah, so well. So if you are on a planet that's orbiting the black hole because the gravity is very strong there, you would still be able to leave. Well, at least in the movie they can still leave that planet. The gravity is not strong enough that they are pulled towards the black hole forever, but it is strong enough that their perception of time is different. So the passage of time for them means that they spend like an hour on this planet that's orbiting the black hole, while the time in a less strong gravitational field further away is moving faster.

Speaker 1:

It's kind of bananas to think that time works that way.

Speaker 4:

It is bananas, yeah.

Speaker 3:

Yeah, it is, but it's because you know space time is this four dimensional fabric that we exist in. So space is just like another dimension with time, kind of as this fourth dimension, tactile, which does behave differently to the three space dimensions. As you know, if you're a human existing because you have control over where you move in space. We don't have any control over where you move in time, but because they're all tangled together in this fabric of space time, if the black hole is deforming space, as I was saying earlier, if you put this, this bowling ball, on the fabric and it stretches, it's also deforming time.

Speaker 1:

Doc, you said something on the podcast that blew my mind. If you fall into a black hole, you said that time and space potentially reverse. Can you explain that? Because I actually had to go sit on a hill and think about that for a while.

Speaker 3:

Yeah, it's a very kind of weird concept, but the effects on it. So, as I was saying just now, you have freedom as a human to move around in three dimensions, in the three dimensional space, but you don't have any control on how you move in time. But when you fall into a black hole, this, this flips over, so you no longer have any control over where you're moving in space and this means that you just accelerate towards the black hole. The black hole just becomes what you are going to, like you will just reach that black hole. There is no control over over that and, conversely, you do have some freedom over how you're moving in time. And I can't tell you how that works or what that would be like, but yeah, it's wild.

Speaker 1:

That is so. But then there's the liberties in interstellar, because there is some manipulation of time inside.

Speaker 3:

Yeah, so, in like, there's so many theories about what happens inside a black hole that there is quite a lot of room for creativity there, because we I mean, we don't understand quantum gravity at all.

Speaker 3:

And and yeah, so there's a lot of freedom once you go to the singularity, because, like so, when Einstein predicted general relativity and black holes or this kind of black hole, he just invented these while not invented. But he discovered that there were these singularities that could exist in the fabric of space time, and this is essentially where space time is infinitely stretched. But we know that infinities don't really exist in nature. So we know that there is some difference between Einstein's prediction and and what is happening in reality, these astrophysical black holes that we're actually observing in gravitational waves and at the center of our galaxy and things, and we don't know what these, these differences are. So there is, there is just a lot of room for speculation once you're inside a black hole. It's kind of like an artist's dream, really, when Christopher Nolan is creating this film, because once you go past the event horizon, like you've got so much artistic license.

Speaker 1:

I love it, sarah, back to you.

Speaker 4:

Thank you so much, jason. I could, I could talk about this forever. I think that it's. It's what we don't know, and your imagination can sort of run wild. Do you think that time travel would be possible through a black hole and theoretically?

Speaker 3:

so not not time travel, but I think well. So wormholes are a thing that is predicted, that people have tried to to disprove and haven't been able to disprove yet. Obviously, we've never observed a wormhole, but if a wormhole does exist, this would be like a kind of shortcut between two different regions of space, which would possibly look a bit like time travel, because it would look like you were traveling faster than the speed of light. If you went between one side of the universe to the other side of the universe through this kind of this tube that connects them both. That means that you can get there without going the longer route. But I think time travel itself is probably not possible, because that would mean traveling faster than the speed of light and we can't do that.

Speaker 4:

And one more quick thing you said that Earth is. If the sun turned into a black hole, the Earth is too far away. We wouldn't lose our orbit. But would Mercury and Venus? Would they be sucked in?

Speaker 3:

No, I don't think that they would. So the sun, if it became a black hole, it would only be about six kilometers across, so it would be very small, and I don't think that. Um, well, I actually don't know what the radius of Mercury's orbit is. If it's, yeah, no, I don't think that it would be sucked in.

Speaker 1:

Black holes. Like this sounds. It sounds like the genie from Aladdin, you know. Phenomenal cosmic power, itty bitty living space, you know.

Speaker 3:

Yeah, no, exactly, I think you've cracked it. That's where all of the genies are living.

Speaker 4:

They live in wormholes, jason. That's how the aliens got here, gosh.

Speaker 1:

Um, doc, are you okay if we invite more speakers up to maybe a pepper you with you, some pepper you, some pepper you with some questions. There we go, yeah.

Speaker 4:

Yeah, yeah Go ahead.

Speaker 1:

All right, so we have. We have our guests for another little bit here. If you have a question about gravitational waves or black holes or, I guess, wormholes, now too, you could request a speaker and then come up to ask a question. So we'll, we'll get you up here. Chris, did you have any questions?

Speaker 2:

No, I've just been enjoying the chat. I did want to add if you don't want to come up to speak, you can definitely add your question in the chat and we will address, or hope to address, it there.

Speaker 4:

Can I ask one more thing?

Speaker 1:

Go for it.

Speaker 4:

Are? Are we trying to put something into a black hole so that we can see what's inside, or is that just never going to be possible?

Speaker 3:

The reason that it's not possible is because we wouldn't be. It wouldn't be useful for us because nothing can escape from the back hole. So if we put anything into the back hole, we would no longer be able to receive any signals from it. So if that was, if we put like a probe or something into a black hole and it was sending out messages to us like via radio or some other kind of electromagnetic frequency, there is no way that we could ever detect those signals. So it would be kind of a yeah, it would be like a useless experiment.

Speaker 3:

We could potentially put something into orbit like around a black hole, but even then the the, as we were saying before, the gravity is so strong that that would cause significant problems in reading out any data or anything. So it's just an incredibly difficult environment to study. Actually, gravitational waves are, you know, one of the best ways to study this extreme gravity regime, because they are coming exactly from this, this point where the gravity is so strong and so extreme that we're really looking at general relativity being pushed to to its absolute limit. So this is yeah, this is one of the best ways to study black holes themselves.

Speaker 1:

Would you have a problem too with a probe rate beside a big black hole Like wouldn't time for it slow so like the data from it would be all messed up Like you could be. You could be waiting like 10 years for it to like say hello back to you.

Speaker 3:

Exactly yeah, it would be a very, a very long drawn out experiment.

Speaker 1:

That's awful, that is so, that is. It's quite annoying. It's so annoying. It's like the closer you get to the black hole, the less you can actually test it Aside from like looking at it maybe.

Speaker 3:

Yeah, it's like they're designed to be hard to study. Einstein described them, as I think he said, like black holes are where God divided by zero, or something which is obviously not allowed.

Speaker 1:

Has anything ever come out of a black hole Like? Has it ever like one weirdo black hole? Like threw up something and you guys are like, whoa, that's weird.

Speaker 3:

So so there are there's this thing that's predicted, which is called Hawking radiation, which I don't profess to understand. But essentially Hawking predicted that over time, over a really long period of time, black holes will evaporate. I think this has to do with like particles near the event horizon, like if you have like a quantum fluctuation and two particles are produced and one like their opposites to each other, so one of them is matter and one of them is antimatter. For example, one of them will be able to fall into the black hole and the other one will be ejected away and this will remove energy from the black hole and eventually they will evaporate. We've never observed this radiation, but this is something that is predicted. Often you have things like, for example, electromagnetic emission from the region around the black hole, but this isn't coming from inside the black hole. It's coming from the effect of the strong gravity on the matter that is spiraling around, like orbiting the black hole.

Speaker 1:

Okay, well, we don't have any other speakers coming up, we'll go to Sarah, and then I have another question for you. Go ahead, sarah.

Speaker 4:

Well, if you ever had an opportunity to go into space and be the first human team to be shot into a black hole, would you do it?

Speaker 3:

That's a good question. Oh, I don't know. Are you offering me the opportunity?

Speaker 4:

Well, yes, because I'm sitting beside you holding your hands, screaming we're all going to die. But yes, I would do it.

Speaker 3:

I think that I probably would do it. I think my curiosity would get the better of me.

Speaker 1:

It'd be a one-way trip though, wouldn't it?

Speaker 3:

It would be a one-way trip. Yeah, that would be the thing that you would have to battle with, but it would be pretty amazing to find out what happens, even if you can never share it with anyone.

Speaker 4:

Maybe at the other end is like puppy planet or something you know.

Speaker 3:

Oh yeah.

Speaker 4:

So puppies and ruled by like one mean cat.

Speaker 3:

Well, this is a hypothesis that I think needs testing.

Speaker 4:

And my other question is if you could travel in space to any planet in our system, what planet would it be?

Speaker 3:

Oh, that's also a really good question. So a lot of them would be extremely unfriendly to be on. So I wouldn't want to go to Venus because that would be an incredibly painful experience, I think. I think I would like to go to Jupiter not to Jupiter itself, but I would like to visit some of its moons, because a lot of its moons seem to be quite interesting from the perspective of potentially being like a human habitable place in the future if we're able to terraform them. So I'd probably go to Jupiter and then hop around on the moons for a bit.

Speaker 1:

Go ice fishing on Europa doc.

Speaker 3:

Yes, yeah, exactly that's what I'm thinking.

Speaker 1:

Let's see if you catch some alien fish under that ice. So I do have a serious question and it does have to do with this whole space time, timey-wimey stuff. I read that so gravity makes time go slower, but I also read that the faster you move, time goes slower Like is that true?

Speaker 3:

Yes, yeah, that's like a kind of equivalent. It comes from the same place in general relativity. So if something's moving really really fast, so if you're on a spaceship that's moving really fast, your experience of time will be different than somebody who is not on that spaceship moving really fast. So if you're moving really fast, you're accelerating, and gravity is also an acceleration. So it's all to do with how time behaves under acceleration.

Speaker 1:

So if you get on a ship that's going really, really, really fast and it would take, I don't know, let's say 20 light years, 20 light years and you're traveling a certain percentage of that. So, let's say the trip would normally take 100 years. But would you experience 100 years, because to us on Earth the distance is 100 years, or would you experience less time than that? Do you know what I'm getting at?

Speaker 3:

Yeah, so you said it 20 light years.

Speaker 1:

Yeah, okay.

Speaker 3:

So that tells you that it would take 20 years for lights to travel that distance. So if you were traveling at a certain fraction of the speed of light, it would take you that fraction of 20 or that fraction more than 20 years to get there.

Speaker 3:

So if it was going to say if it was going to take 100 years for you to get there, moving at some like human accessible speed, but it was going to take 20 light years to get there, if you're traveling at the speed of light, if you're traveling at just less than the speed of light, then it's going to take you just more than 20 years to get there.

Speaker 1:

But would you experience that as that time, though? That's the thing that blows my mind, like would time be slower for you because you're moving so quickly.

Speaker 3:

That's a good question. You would experience less time than the people on Earth would observe you to take, so you would experience less than 100 years.

Speaker 1:

That's wild, yeah. So like technically, you could be immortal if you just like. Flew very quickly through space like Han Solo, if he's always doing hyper jumps, right.

Speaker 3:

Yeah, I mean it depends on the eventual destiny of the universe. I suppose I guess, If the universe is closed and you manage to make yourself exist for long enough, that you're around when the universe crashes back in on itself and they're still not going to survive forever. Okay, Touche the universe will always get you. It'll always get you Touche.

Speaker 2:

Dr Isabel, can you share a pet story with us? Do you have any pets?

Speaker 3:

I don't have any pets right now. I used to have some giant African land snails. That's my pet of choice. They're the best for like a low maintenance and also very interesting to look at pet. So I used to have a giant African land snail. So I've had two. Both of them are slightly no longer with us. The first one was called Juan, the second one was called Herschel, and they're both great. They're both really interesting to hang out with.

Speaker 3:

I did talk about some pet stories on the podcast recording that we did before, but I'll also share another one, which is that when I first went to university I was missing my family and I was missing my snail, which was Juan at that point, and I would have Skype calls with them because Zoom at that point wasn't such a big thing. So we were all using Skype and one of my parents picked up my snail so that I could see him on the screen and because snails they can't really see very well but they are sensitive to light. So when they lifted him up to the screen, his little face, his little antenna swung towards me and it was like he was looking at me and I hadn't cried seeing my family on Skype, but I did cry seeing my snail looking at me on the Skype screen.

Speaker 1:

Oh, If you have the ability to Google, you can Google giant land snails. They're huge, they're the size of your hand. They're very, very big.

Speaker 3:

Yeah, that's super cool.

Speaker 4:

Do they have personalities? Are they like fun pets? Yeah.

Speaker 3:

I would say they're probably not as energetic or as fun or as individual as a dog or a cat, but they do definitely have different characteristics. Like the two different snails that I had, juan was definitely more curious and more inquisitive and a bit more energetic, and then Herschel was a little bit slower. There's not even because they were slightly different breeds, because Herschel was a jade giant African land snail which has like a white body and a brown shell, and they typically tend to be a bit more timid, I think.

Speaker 2:

Like to be eat.

Speaker 3:

Oh, all kinds of things. So they eat all kinds of vegetables. You can also give them a little bit of toast if you want to, but not too much toast.

Speaker 1:

I love this. I love this. They eat toast.

Speaker 3:

Just a little bit of toast, mostly like cucumber and tomatoes and mushrooms and stuff, but you do have to make sure that you're giving them enough calcium. So usually people put a little bit of cuttlefish shell into their tanks. That's really good. You can also grind up egg shells and feed them that, because they have to build their own shell. You can actually watch them like building their own shell, which is pretty amazing, and they need a lot of calcium to do that. So you need to feed them lots of calcium to enable that, and also it means that they can repair their shells if they get damaged at all.

Speaker 2:

That's cool.

Speaker 3:

My turn was to do that too.

Speaker 2:

Oh, that's cool.

Speaker 1:

You guys could talk about shelled pets, Chris.

Speaker 2:

Yes, let's celebrate.

Speaker 1:

Oh my God, I walked right into that one. Why do I do this to myself every time with the puns? I don't know if anybody has any other questions, but I think we can probably move towards wrapping it up, if we don't, because it is super late for the doc. She is awake at like two o'clock in the morning right now.

Speaker 2:

No, it's three o'clock now, jim. Okay, yes, yeah, moment.

Speaker 1:

Yeah, Okay, looks like there's no. Looks like there's no more questions. There were some good comments in the chat. Kevin Reader said there's a science fiction story about talking to aliens on a neutron star and gravity time is different. And the other thing is that he did mention I believe this is true that black holes are really really far away, so we don't have the technology to even get close to them anyways.

Speaker 3:

Yes, that is. The ones that we know about are far away the ones that we know about. Yeah, well, there's this theory that there's an extra planet in the solar system, planet nine, and there's a theory that that's the black hole, because we haven't seen any evidence of it.

Speaker 2:

We've only seen its gravitational effects.

Speaker 3:

Oh my God what. It's a very astrophysical motivation that I know of for it to be a black hole. It's more just saying like we see the gravitational effect of something else but we can't see what it is yet. But there was a really great paper proposing that it was a black hole, where they had a to scale diagram of the black hole itself, because this would be quite a light black hole, like not very massive, so the black hole itself, the diameter of the black hole, would fit onto an A4 piece of paper. There's this big black circle on this page in this paper which was saying like this is what the black hole would look like, like exactly this size.

Speaker 1:

Okay, could you fall into something that small, like would like it would suck you into it. If it was like a human falling into something the size that little like you would just yeah.

Speaker 3:

What? Yeah, if it has a gravitational attraction, then you would definitely this. This would be a real danger for spaghettification. If that has like a planet mass and you're near it, that's going to, that's going to be painful.

Speaker 1:

Oh my God, this is. I love this conversation so much.

Speaker 3:

So, on the point about the book, was that book called dragons egg?

Speaker 1:

I don't know, kevin, just put it in chat.

Speaker 3:

Okay, I think I've read that book as well.

Speaker 4:

Oh, wow.

Speaker 3:

It's about like an alien civilization evolves on the surface of a neutral star. It's a very cool, very cool concept, very cool book. It's all about like how it's like a hard sci-fi book about how like evolving on the surface of a neutral star would be, you know, very different because of different chemistry and the influence of the really strong magnetic fields and the much stronger gravity and so on. It's very, yeah, very interesting, but I really love like hard sci-fi books.

Speaker 1:

Cool. Well, I think we'll do our wrap up, Chris.

Speaker 2:

Yes, did you see in chat? Canadians, we can't have snails.

Speaker 1:

We can't have snails.

Speaker 2:

Oh, can you? No, it's, they're on the prohibited list.

Speaker 1:

What are they going to do? What are they going to do? Escape into the Canadian wilds and replicate themselves? I don't think so.

Speaker 2:

No, it's just regulated. The importer handling of the listed snails for commercial or personal use is prohibited, and snails commonly known as giant African land snails or giant African snails are included within that list.

Speaker 1:

Are they worried? It will like escape and grow to giant sizes in, like the Canadian tundra.

Speaker 2:

Like they'll be car-sized snails All.

Speaker 1:

I have is the information Ride them around like.

Speaker 2:

No no.

Speaker 1:

All I have is the information that you have to feed them a lot of.

Speaker 4:

Jason, you should be more worried that she Googled it because she wanted to get a whole herd of large African snails, and that's where your concern should be.

Speaker 1:

I never thought that way. That's going to be a lot of toast. I'll tell you that we're going to have to like stock up on toast.

Speaker 2:

I do not want any government organization coming to us and checking out our stuff. Remember, remember the zebra mussels.

Speaker 1:

Yes, I also think I'm on Cesis's watch list with what I've Google for being a science teacher. Just FYI, chris. So Cesis is like the Canadian FBI or something I don't know.

Speaker 3:

Okay.

Speaker 1:

Anyways, there's very polite.

Speaker 3:

I'm sorry that you can't have land snails, giant African land snails. They're also prohibited in Australia, I think because they, because Australia has a lot of like, very, very important native flora and fauna that can't be thrown out of whack by the introduction of any kind of foreign influences and the snail would. A snail of this magnitude would be too much.

Speaker 1:

That seems unpar for Australia.

Speaker 2:

It's well, and plus they won't kill you, which most things in Australia will. So that's probably why they're also.

Speaker 1:

You just wait, it'll like mate with some kind of like creepy snake and then you've got like a deadly poisonous land snail down there, oh gosh, yeah.

Speaker 3:

They do have a very poisonous snail in Australia which is like a it lives on. I think it lives underwater and it like has this horrible poison.

Speaker 1:

It's got a harpoon right, the deadly harpoon that shoots out yeah.

Speaker 3:

I guess that's what that snail is called, like a conch Conch.

Speaker 1:

No, it's probably purple, yeah, probably. I mean, I'm Googling deadly Australian snail and probably it's a sea snail. It's a cone snail. It's one of the cone snails.

Speaker 3:

Cone snail. That's it yeah.

Speaker 1:

There we go.

Speaker 4:

You're both going to have to move after this Google search Okay.

Speaker 1:

What we're going to do. A little wrap up. Everybody, thank you for coming to side chat tonight. A big special thanks for our guest, dr Isabelle Ramirez Shah, who stayed up super late to talk to us about gravitational waves and black holes. Thank you so much, doc. We really appreciate your knowledge here tonight.

Speaker 3:

Thank you very much for having me. This has been fun Okay.

Speaker 1:

Take care, if you missed part of this, it'll be recording on the science podcast and if you want more, we have a full interview with, like our standard questions on the science podcast as well, which will be coming up in two to three weeks. So this one will come out first, and thank you to everybody who well, I guess it was just Sarah. Sarah, thank you for asking some questions tonight. I appreciate that. So, on the information docket, chris, are you excited about Comic Con? Bunsen and Beaker, our guests at the Comic Con. I am.

Speaker 2:

I just want to say, if you're not following Dr Isabelle, please give Dr Isabelle a follow. I'm sure there's excellent information. You posted something about a virtual test with Barbie, the Barbie movie. It was at a virtual test. What's the test called?

Speaker 3:

Sorry, I managed to meet myself.