Planet artsci Episode 10: Magnets, aliens and why your dog poops in circles Transcript
Planet Artsci podcast with Professor Bryan Gaensler
PLANET ARTSCI: Magnets, aliens, and why my dog poops in circles on this episode of Planet ArtSci.
PA: Let’s talk about magnets. It’s been a long time since I studied magnets in elementary school or maybe in a junior high science class. I didn’t really understand how they worked back then, and I have to admit I still don’t really understand how they work. They might as well be magical – forged in the fires of Mount Doom or powered by midichlorians. But magnets surround us every day. They’re in our cell phones and credit cards, our cars and computers and on our fridge doors. Earth’s magnetism protects our atmosphere from harmful cosmic radiation. There are species of birds that tap into the earth’s magnetic field to aid in their navigation. There are stories about magnetic cows and fish, even my dog seems to have a magnetic connection in the way he circles and circles trying to find just the right spot to do his business. We’ll get into all things magnetic with today’s guest Bryan Gaensler who is a bit of a magnet freak.
Professor Gaensler is yet another Australian export alongside Cate Blanchett, AC/DC, and The Wiggles, and he’s the director of the Dunlap institute for astronomy and astrophysics at U of T. Professor Gaensler’s also the Canadian Science Director for the Square Kilometre Array – an enormous radio telescope being developed through the combined efforts of scientists from a dozen countries. When it’s finally online in just a few years, the Square Kilometre Array will be 50 times more sensitive than any other radio instrument and be able to survey the sky ten thousand times faster than ever before. So we’ll chat a bit about magnets, we’ll chat about the Square Kilometre Array, whether there’s intelligent life in the universe beyond our planet, and again, why my dog poops in circles. This is Planet ArtSci.
BRYAN GAENSLER: I like to think of myself as the unofficial international spokesperson for magnets. Magnets really are the source of so much in our modern electronic lives and no one ever gives them a second thought. One of the amazing things about magnets is that we actually understand how they work. There’s so many things in physics around us that we don’t really understand in detail how it actually works, but magnets we really do. We understand down to a detailed atomic level what a magnet is and how they work the way they do. So you might think, why would anyone work on magnets; we understand them. So we understand how they work but we don’t know where they come from. To make a magnet, there are a few ways you could do it. You could stroke a piece of metal with an existing magnet, you could run an electrical current through something and that makes a magnetic field. So that sounds simple but it’s a chicken and egg issue. Because if you make a magnet by stroking it with another magnet, where did that magnet come from? If you make a magnet by running an electrical current through something, where did that electrical current come from? It came from a power station. How was that electrical current made? It was probably made using magnets. Every time you have a magnet, you need another magnet to make it. So you very quickly ask a cosmological question, which is where do all the magnets come from? And you have to then face the question, where did magnetism begin? Where did the first magnet come into being and how did it happen?
PA: How close are we to having an answer to that question?
BG: One of the reasons I like working on magnets is ‘cause we are barely into the first chapter. This is a really hard problem. It’s going to take decades. I think when we get the answer it’s not going to be the answer is “x,” but it’s going to be some sort of subtle palette of different forces interplaying so we are a long way from getting the answer to that, which is great because it means I’m not going to run out of things to do and we’re going to find all sorts of other amazing discoveries by accident along the way.
PA: Two questions. What do galactic magnets look like and where did all the magnets come from? You kind of touched a little bit on the second part. Let’s talk about the first part. What do they look like?
BG: We know that our own Milky Way galaxy is a giant spiral or pinwheel – quite a beautiful glowing yellowy-pinkish-bluish beautiful giant pinwheel. We think that the magnetism actually follows the spiral arms. So instead of a bar magnet where you have a north pole at one end and a south pole at the other end, you can think of a galaxy of having north poles at the ends of the spiral arms and the south poles at the centre. Now we don’t know if every single arm of a galaxy they’re all at the north at the end and south at the centre or whether they alternate. We don’t really know, but the magnetism seems to beautifully follow the spiral arms, which suggests it’s got something to do with the gentle gradual rotation of the galaxy. This magnetism has a massive impact. The actual strength of the magnetism is quite weak. It’s about one millionth the strength of the magnetic field on the surface of the earth. So if you were to fly through interstellar space with a compass and weight, well the needle will take a very long time to gradually swing north or south. But because galaxies are so big, that weak magnetism integrated up over the massive volume of the galaxy, ends up being a huge amount of energy and has a real impact. For example, the earth and everything else in the universe are being constantly bombarded with these incredibly high energetic atomic particles called cosmic rays. This are a bit like the particles that are accelerated at the Large Hadron Collider but the energies these particles reach is billions of times higher than the Large Hadron Collider. So there’s something natural in the universe – we’re not sure what it is – that is, without any technology or conscious thought, accelerating particles up to energies unimaginable, much higher than we can make. And while we don’t know what it is, we do know from various arguments that accelerator has magnetism in it. It’s the magnetism which is acting as the accelerator. So this magnetism throughout the universe is acting as a natural particle accelerator shooting these particles up to almost the speed of light and it’s these particles constantly crashing into the earth, which creates the radioactive carbon that allows carbon dating. It’s thought to create the charge particles, which result in lightning and it also potentially a big factor in driving evolution. We know that evolution is random mutations and then the environment selects for the organisms that mutate in a way that allows them to have more offspring. Well why are there random mutations? They don’t just happen; DNA is designed to perfectly replicate itself. You get random mutations ‘cauSe there’s an error, and one the reasons why you get errors in DNA replication is ‘cause right at the wrong moment a particle, created by some magnetic field on the other side of the universe, comes smashing into the atmosphere and hits a DNA molecule and breaks it or changes it. The whole fact that species evolve and that humans have somehow grown out of single-cell organisms is due to intergalactic magnetic fields slingshotting these high energy particles across the universe.
PA: Can you talk a little bit about the weirder side of magnetism?
BG: Every scientist has a secret; they have another scientific topic they would like to moonlight in if they could do it all again. And for me, if I could do it all again, I would work on this field called magnetoreception, which is the study of how living organisms actually sense magnetic fields. So the standard thing is that we know that various species of birds can sense magnetism and that’s how they migrate from one side of the world to the other. But much more interesting is the recent realizations that all sorts of other animals have some sort of sixth sense where they can somehow sense magnetic fields. So people have looked at images of cows on Google Earth and shown when cows aren’t doing anything in particular they tend to sort of line up north-south. They’ve looked at fish in buckets at fish markets, and the fish as they’re thrashing around the bucket tend to line up north-south. As you mentioned one of the most bizarre ones is there was this 0study where they actually tracked about 50 dogs for like a month measuring which direction they poop in and discovered there’s a statistical excess of poops that line up north-south. So as you say dogs always seem to spend a lot of time trying to get in the right position and they obviously feel a bit more comfortable when they’re lined up with the earth’s magnetic field.
PA: And now I’m going to take a compass with me whenever I walk my dog just to check this out. Is there any indication that humans can perceive magnetism in the same way or in a similar way?
BG: There does seem to be evidence that humans have some vestigial and probably not very useful residual magnetic sense left over from some early phase of evolution. People have shown that your vision, done eye tests when you’re standing along a magnetic field line versus across it and shown that your vision depends on that. The most unusual study that’s been done has suggested that your levels of melatonin that generate while you’re asleep depend on the strength and orientation of the earths field and so those shown that depending on the local magnetic field you either have bizarre dreams or normal dreams depending on what the magnetic field is doing. People have also shown that you have a better night sleep when you’re sort of aligned with the field versus across the field. There’s this expression about getting up on the wrong side of the bed; I would say you should look at whether your beds pointed north-south or east-west. So I think this is all sort of very preliminary, but there are these hosts of very different studies that all show in different ways there are things in our brain that are every slightly affected by the strength and direction of magnetism.
PA: You are also the Canadian Science Director for the Square Kilometre Array, a radio telescope. What exactly is the SKA?
BG: So the SKA, the Square Kilometre Array, is a project and a plan to build the most powerful radio telescope ever constructed. Normally when people think of a telescope they either think of a tube with an eye piece in it that you might have in your backyard or they think of something like the Hubble Space Telescope. What those two types of telescopes have in common is that they focus and magnify normal visual light. But light is only a tiny part of the electromagnetic spectrum, so it turns out the universe isn’t just shining in the light we can see with our eyes but it’s also shining in all other different types of light. You might not think of them as light but you heard of them: x-rays, ultraviolet, infrared, and radio signals. So a radio telescope simply is another way of looking at the sky but in the light of radio waves, and it normally looks like a big satellite dish. The bigger the dish, the more you can see. The biggest dishes in the world are hundreds of metres across but they’re still not big enough to see the things we’re looking for. So you can either build a dish kilometres across which would not be very practical, would probably fall down as soon as you tried to steer it, but you can also use the magic of electronics and modern computing to build a very large radio telescope by having lots and lots of small dishes spread apart almost as far as you want, linking them up with optical fibres and connections and through computers simulating a giant telescope. So, as the name suggests, the Square Kilometre Array will be an array of thousands of dishes spread across an entire continent that when you add up the area of all the dishes combined, you have the equivalent of a dish that is one square kilometre in size. So this will be 100 times bigger than any radio telescope that’s ever been constructed before and it will be able to answer fundamental questions about how the universe actually works.
PA: And where will this SKA be?
BG: It turns out that the radio spectrum is very broad. We want to cover a huge range of frequencies from frequencies much much higher than radio right down to the middle of the FM band. And you can’t do that just with one design, so we’re building two Square Kilometre Arrays: a traditional set of dishes that will steer and point and that will be in the desert of South Africa, and we’re also building what look like a bunch of fancy coat hangers and those will be targeted at very low frequencies and those will be in Outback Australia. Trying to measure a very faint signal with a radio telescope is a bit like being at a party and everyone is yelling but there’s someone you really want to talk to one the other side of the room and they’re whispering. You can’t hear them because you don’t have good enough ears. That’s what it’s like using a radio telescope in most places on earth because there are FM radio, there are mobile phones, there are microwave ovens, there are people starting their cars – the spark from the spark plug creates a big radio pulse – there’s aircrafts flying overhead, there’s radar, there’s GPS. Whatever radio frequency you pick, the whole sky is just full of yelling and shouting and ruckus. So if you want to actually hear the signals from the universe, which are millions and billions of times weaker than that, then you have to somehow find a place on earth where radio signals are not being generated. Two unique places that give us what we need are Outback Australia and the equivalent in South Africa. In both cases, there’s almost nothing there and so you can actually get rid of all that shouting and yelling and listen to what the universe is trying to tell us.
PA: What do you expect or hope to hear once that array is turned on?
BG: We have some very specific things we want to see. We want to see the echoes of signals from the very first stars being formed. We want to understand where the magnetism in the universe comes from. We want to make precisions measurements to test whether Einstein’s theory of gravity is correct or not. There’s a whole bunch of very well defined goals where we know exactly what to do; we just need the telescope to do it. But what’s really exciting is that if you look at previous telescopes, every telescope has had a hit list of very specific experiments it was designed for. But then if you then say, what did that telescope end up being famous for, it’s always something completely different. So a classic example is the Hubble space telescope, one of the most successful telescopes ever built and still going strong after 25 years, it was built to measure the distances to galaxies. We didn’t know how far away a lot of galaxies were, and it was able, successfully, to very precisely measure the distances. It did what it was designed to do. But what is Hubble most famous for? Well for some Nobel Prize winning work where they discovered dark energy – this mysterious force that is pushing the universe apart and making it accelerate. No one guessed when they were designing Hubble that it would discover dark energy and yet that’s probably its most important discovery. So in the same way while we’ll certainly do all these things that we planned with the Square Kilometre Array, the most exciting things it will do are things we couldn’t possibly even guess at but will finally be revealed with the incredible sensitivity and power of this brand new facility.
PA: How much of the universe are you going to be able to tune in to?
BG: So if you’re trying to test gravity, then we will be able to study objects in our own galaxy and see how they behave under gravitation. So in that sense the percent of the universe you’d be studying for that experiment is absolutely tiny. When you are trying to understand where the first stars come from, you are looking for a very faint signal that’s coming from the entire sky, so there you’re sampling a huge fraction of the universe. Some experiments will sort of look at the whole universe, others will look at specific objects in our own galaxy. The area that Hubble can cover when it takes one snapshot of the sky is miniscule. It’s smaller than your fingernail with an outstretched arm, so there’s no way, even after 25 years, that Hubble could map the entire sky. You have to pick a very tiny object and then point it at it. If your object is big then forget. For example, if you say can we make a nice picture of the moon with Hubble, the answer is actually no you can’t. It’s because the moon is just too big, even though the moon is not that big on the sky. So the revolution like the Square Kilometre Array is leading is essentially replacing the traditional approach with sort of a fish-eye lens or a wide angle camera. The Square Kilometre Array will be able to look at the whole sky – every part of it in detail – in a matter of hours. With previous telescopes this would have taken years and years and years and now you can just do it in a matter of hours. And that’s really exciting because once you’ve done it once, you can do it again and you can say, what has changed. And if something has changed, then you can then steer other telescopes towards it and study that explosion or that flare or that collision between two objects. So the big challenge for us is to have to deal with this tsunami of data. One of the things which we’re going to have to do, which is very emotional and challenging problem for astronomers, is that we’re used to going away with the data and playing with it later and fiddling with it and trying different things. We won’t be able to do that anymore. We’re going to have to make decisions in real time and we won’t even be able to make them as humans, we’re going to have to have algorithms or computers making the call for us as the data race past them saying no, no, no, oh that’s interesting, no, no, no, no, no. And we will look at it later at a vastly watered down, diluted version of the raw data stream.
PA: Outside of your own research and your own interests, what areas of astronomy and astrophysics are exciting you that you’re looking forward to see where that research goes?
BG: One area that the University of Toronto is very strong in and I think got a big head start on a lot of other places is this field of exoplanets – the idea that there are planets around other stars. When I was growing up, there were the planets in our solar system and that was it. And now we have literally thousands of planets around other stars and some of them are a lot like earth and others are like how did the universe come up with that; we don’t have any planets in our solar systems like them at all. We’re realizing that there’s lots of different ways that planets form. We don’t really understand how that happens. We’re now not just finding planets but people here at the University of Toronto and elsewhere are working on exoplanet meteorology, like actually forecasting weather and atmosphere and cloud coverage on other planets. And of course then the inevitable question is, are we alone? We do know of planets around other stars now that almost certainly have liquid water, perhaps have oxygen in their atmospheres, so does that mean there’s life there? We don’t know, but we will start to answer those questions in the coming decades. The idea that we don’t just have to look at Mars or Jupiter but that we can start to make maps and ask detailed questions of planets are on other stars, to me that’s science fiction and the fact that science fiction is real and that there are conferences on this every month, just shows you the power of human thought and ingenuity that we can talk about these things even though we never go there. All we do is sit here and collect gentle light that’s coming in from thousands of lightyears away but we can talk in detail about planet compositions and magnetic fields and atmospheres and weather – just spectacular science.
PA: DO you expect us to discover intelligent life in the universe beyond this planet?
BG: The universe is a very big place. There are billions and billions and billions of galaxies, each with hundreds of billions of planets in it, so I think just based on the numbers that there is other life out there. I think the big question then is, is all the other life in the universe just moss or bacteria or plants or is there anything intelligent? There are so many things that have had to have happened to have got intelligent life. One analogy I heard is that to get intelligent life out of the primordial soup it’s a bit like having a junkyard and having a tornado sweep through it and somehow the wind of the tornado puts together a brand new Boeing 747. Theoretically it could happen, but you know it’s just never going to take place. Somehow it did happen here. Has it happened anywhere else in the universe ever? No one knows. My own gut is I actually think that in terms of intelligent life that we are unique. I think there is probably lots of other life in the universe, but I think it’s probably all very simple or uninteresting by our standards, even that would be a spectacular discovery. Intelligent life, I don’t know. I’d be happy to be proven wrong but I think that we’re either alone or that it’s very very very rare. So actually finding intelligent life, having a conversation with it, we absolutely should look. I have no reason to think to justify my beliefs. We should look and I’m glad people are looking, but I think unfortunately it’s probably we’re alone in the universe.
PA: This episode has been brought to you by the letters A and S at the University of Toronto. I’m Barrett Hooper. Thanks for listening.