Dr. Brooke Simmons is an astrophysicist researching galaxies and black holes, specifically the co-evolution of supermassive black holes and their host galaxies. When she isn’t spending her time figuring out the mysteries of the universe, she is also on the Zooniverse and Galaxy Zoo teams, which allow regular people to contribute to scientific research, such as the study of why so many people effortlessly break the Prime Directive in Star Trek (I think).
We caught up with Dr. Simmons below and got her to give up the juiciest details about supermassive black holes and the mysteries of universe (hint: it definitely sounds like she’s close to discovering alien life):
We totally understand pretty much everything there is to know about supermassive black holes and their host galaxies, but for our readers who don’t, could you describe just what a supermassive black hole is?
Black holes are an extreme of gravity, which we all experience every day. As far back as the 18th century scientists were speculating about what would happen if there were an object in space that was so dense, its escape speed was higher than the speed of light. Nothing moves faster than light, so anything that got close enough to it couldn’t escape: it would look like a lightless (black) hole in space.
The confirmation that black holes actually exist is more recent, and they can have a huge range of masses. Black holes are the natural endpoints of the evolution of stars much more massive than our Sun. Any galaxy with lots of stars will end up having some stellar-mass black holes scattered about, and new ones are created all the time as massive stars die. Those are really cool objects, but they’re only maybe ten times the mass of the Sun.
Supermassive black holes were formed, we think, in the very early universe. We haven’t directly observed their formation yet (hopefully we will with some of the next generation of telescopes), but theoretical work tells us it was possible. Conditions had to be just right, and those conditions were pretty common way back then (and are very uncommon now).
So, very massive black holes formed very early. And black holes don’t get less massive, because nothing can escape from them. They only ever stay the same (if nothing is falling in) or grow (if something is falling in). So those big black holes had billions of years to get bigger and bigger. Today we talk about supermassive black holes as generally being anywhere from a million to around ten billion times the mass of the Sun. Most galaxies have a supermassive black hole at the center.
What is the importance of supermassive black holes? What effects do they have on the universe?
Supermassive black holes are typically less than 1% of the total mass of the stars in the galaxy they live in, and they’re very compact for their mass, whereas galaxies are very, very spread out. So supermassive black holes are just one tiny piece of the whole by those standards. However, they really pack a punch. When stuff is falling onto a black hole, the matter tends to heat up, and it radiates away some of its energy before it falls in. The immediate surroundings of “active” black holes are complex systems, and the energy they output can make them the most luminous objects in the Universe. The brightest of these, called quasars, can outshine their whole galaxy.
That matters because light is energy, and that’s a lot of energy that gets pumped back into the galaxy. It’s enough to potentially dramatically affect the evolution of the galaxy. Also, some active supermassive black holes (which we call active galactic nuclei, or AGN) unleash much of this energy via a jet of light and particles. Jets are extremely focused and powerful and can extend well beyond the galaxy itself, so AGN can also impact the large-scale environments around galaxies. Overall, these compact engines turn out to play a really big role in the long-term evolution of galaxies in the Universe. Part of my work is trying to figure out the details of that role.
What drew you to this type of specialty? What is the most interesting/rewarding aspect of your research?
Fundamentally, I’m drawn to astrophysics because I think it’s amazing that we can know any of this stuff. As an observational astrophysicist, I don’t get to run my own experiments in a controlled lab. I have one experiment and it’s called the Universe and I can’t control any of what happens in it and I can’t even see all of it in the same way at the same time. My challenge is to figure out how to make sense of it. It’s a bit like if aliens* did a rapid fly-by of Earth and only had time for one picture, and had to try to piece together how human civilization works from that one picture. Getting it right requires both logical and creative thinking, an ability to ask the right questions, and careful attention to detail. Over time we’ve been able to take better and better pictures, but by the Universe’s standards almost no time has passed between them, so it’s still mostly like having one picture to work with.
Scientific research pays off in multiple stages. First, there’s that moment when all your careful planning and analysis comes together and you get a result that pops up on your computer screen, and for a little while you’re the only person in the world who knows this particular thing about the way the Universe works. That’s pretty great. But it’s even better to share it with your colleagues, the wider scientific community, and the public. I love contributing to the sum of human knowledge, even in a small way.
* I have no idea if there are aliens, and if I did know I probably wouldn’t tell y—-no wait, I would totally tell you and everyone else in the world. I’d publish that data so hard.
Are astrophysicists pretty tired of “supermassive b-hole” jokes by now or do they still have legs?
You’re the first to make that one to me! Seriously – I’ve heard lots of puns and jokes on black holes, but never that specific abbreviation. I like it. As for “supermassive b-holes with legs,” how do you know my ex?
What exactly is the Zooniverse, and Galaxy Zoo in particular?
The Zooniverse is a website where anyone can make a contribution to real research, in just a few minutes. That sounds like a fitness
infomercial or something, but it’s real, and free, and our volunteers (over 1.5 million at this point) have helped with research questions from astronomy to zoology.
Galaxy Zoo was the first project in the Zooniverse. One of the most important things (physics-wise) we can measure about a galaxy is its shape and appearance: does it have spiral arms? is it merging with another galaxy? does it have clumpy areas in it, or is the distribution of stars smooth? All these questions involve patterns that are easy for people to detect, but difficult for computers to reliably spot. So when you visit galaxyzoo.org, we will show you an image of a galaxy and ask you questions (in plain English, or a variety of other languages too), and you click on your answers, and when you’re done, you’ve contributed to science. The science team (myself included) collect multiple classifications for each galaxy, and we combine them to produce a consensus answer. Those answers are very reliable, even though sometimes people aren’t sure of their answers, that all averages out. Galaxy Zoo has used classifications from volunteers to do a huge variety of galaxy science, which is published in over 50 scientific papers.
This need for people-powered research spans many fields of research, and that’s why the Zooniverse has launched over 80 projects to date. We’ve got several astronomy projects, multiple ecology projects (one of my favorites involves identifying animals in the Serengeti), and we’ve now got projects where people are digitizing and transcribing collections like Shakespeare’s archives and artist’s notebooks from the Tate gallery. There’s something for everyone, and everyone who contributes gets credit for their work whenever we publish anything.
Here are some questions I grapple with all the time: Where does the universe end? And assuming it does, what is beyond that? Who created the universe, and who created that? With a much deeper understanding of the universe, how do you reconcile some of these things? Does the thought of what lies beyond the universe itself and what created it just consume you? With that in mind, how do you think this interview is going?
Ooh, a multi-question question. Here goes:
1) As far as we know, it doesn’t end, it just keeps expanding forever, getting colder and blacker, until all the stars have gone out and all the matter everywhere has fallen into black holes and then the black holes slowly evaporate and it’s all just a sea of elementary particles, forever. Maybe. Or possibly not, but either way it’ll be a long time from now so don’t stop contributing to your pension.
2) Oh, for that first question you meant more like a physical end-of-the-road with a boundary or an edge, that kind of end, not the gradual heat death of the Universe. Oops. In that case, it could be finite but not have a boundary, analogous to how an ant crawling on the surface of a basketball could walk forever and never face an obstacle but also not be in an infinite space. It could also be just one universe of many, each of them “bubbles” in some kind of larger space. That’s an active area of research but it’s purely theoretical for now, almost more science fiction than the kind of science we can test with experiments. For now.
3) Some years ago I went to a really interesting conference called “Why Is There Anything?” that brought together cosmologists, philosophers and theologians. By the end of the conference I’d decided we probably need at least two of those three categories to answer any question in this area starting with “who.”
4) Scientists get pretty used to not knowing things. Because it’s our job to try to find answers and there are way more questions than we have time to answer given that we also need to do things like sleep, eat, and socially interact with others, we generally feel comfortable living with uncertainty. So I’m okay with not having reconciled everything. Yet.
5) It’s a good thing that human beings are adaptable, such that if you spend most of your day thinking and talking about black holes billions of times the mass of the Sun, or the gradual evolution of the Universe from a nearly uniform sea of hydrogen gas into a cosmic web of dark matter and galaxies and stars and planets, it doesn’t take long before you learn to suppress the awe factor. If we couldn’t do that, we’d be paralyzed with wonder and wouldn’t get any work done. Sometimes I let it wash over me, because astrophysics is awesome, but mostly I’m more like “oh, that galaxy is only 100 million light-years away from us? Cool, it’s basically next door!”
6) As you can see, I get a little wordy when I talk about space. I’d say our status depends on whether you have a page limit.
You travel through a black hole and are transported back in time. What snack would you eat when you went to see Interstellar for the first time again?
I like to have a bit of something sweet while watching a film, so maybe some chocolate. Then of course you’d want something a bit salty to balance it out, like popcorn, or the tears of all the physicists everywhere who bought the hype that Interstellar was going to get the physics right.
(The black hole simulation and visual was brilliant, though.)
What happens if quarks get separated at the edge of a black hole?
I saw a film about that once, and I just ended up angry because there was definitely enough room on that floating door for two quarks. They didn’t have to be ripped apart!
(Sorry.)
Actual answer: the edge of a black hole isn’t like the boundary between air and water. If you crossed over it, you might not even notice at first (until you tried to leave). It’s not like there’s an edge where nuclear physics is all good on one side and then immediately breaks down on the other side. While there is theoretically a region where the tidal forces pulling stuff apart would be stronger than the strong force that binds quarks together, it’s well inside the black hole.
“You jump, I jump, right?” – quarks on the edge of a black hole
You’ve created your own method to determine bolometric luminosities of obscured central active galactic nuclei, but what’s your method for the perfect cup of coffee?
First, create the Universe…
My perfect cup is actually a cup of tea. Yorkshire Gold if you’ve got it, on the strong side but not oversteeped, milk, no sugar. I enjoy coffee, but I love a “cuppa.”
A lot of people think humans should focus on what’s wrong on Earth before going to space. Why do you think it’s so important to spend time and resources on the universe?
We can do both! It’s not really an either/or choice; it’s more like a neither/both choice. Some of the most revolutionary advances and
innovations in the world have come from research that had no direct practical application. Even research that is intended to lead to a practical advance is generally based on the results of earlier research that had no practical application.
The computer I’m using to write this message couldn’t have been invented if there hadn’t first been research to develop and test the theory of quantum mechanics. The website this will be published on exists on a framework developed largely by particle physicists who needed a better way to keep in touch about what happens when you slam protons together (which you do just because you want to know what happens). The WiFi I’m using to connect to the web owes some of its technology to advances made by radio astronomers. Some of the research tools we’ve developed for dealing with scientific data in the Zooniverse turn out to also be useful in analyzing data from natural disasters (we give our results to first responders on the ground), so even on a smaller scale there are serendipitous practicalities.
The idea that we should only fund research that directly applies to a practical problem rests on the assumption that humans are good at making rational predictions about what’s going to be the Most Useful Thing at some future date. And, frankly, we kind of suck at that. I mean, Twitter was developed originally as a way for small groups to chat about inconsequential things, and now it’s hugely influential and has played a substantial part in political revolutions and artistic expression and the erosion of basic human decency. Its creators were just trying to combine texting with IMing and see if maybe they could sell it. We. are. the. worst. at trying to decide in advance what’s going to be a big deal.
In fact, the best predictor of how useful research will be to the world is the curiosity of experts. That was a key finding of a report from the Congressional Budget Office (they’re a non-partisan group of non-scientists, so pretty objective about government spending on scientists) when they studied federal support for research and development. They found that the type of research that had the highest return on investment was peer-reviewed “basic research,” aka research-for-the-sake-of-it-
I know that’s a hard sell, in part because by its nature it is unpredictable, but over time it’s also very reliable. Going to space and spending time and resources on the Universe isn’t the same as sending a rocket full of cash up to dissipate into nothingness. That money gets invested on Earth, and it pays off for people on Earth.
Also, space is awesome and we should learn more about it, full stop.
Aside from alien lifeforms, what interstellar discovery could happen tomorrow that would really capture the attention of the entire world?
I can think of several candidates for this. Until recently gravitational waves would have been at the top of the list, but we detected those for the first time last year!
There have been some papers published in the last year or so that analyzed the orbits of rocky, icy bodies far out in the solar system and realized that their distribution is really hard to explain unless there’s an unknown planet out there. People are calling it Planet 9, and there are now some predictions for areas in the sky that we might find it. It’s really very far out, near the edge of the solar system, but our current telescopes could detect it. There’s even a Zooniverse project (backyardworlds.org) asking the public’s help to sift through the images. It’s been a very, very long time since we discovered a new planet in our own backyard!
Also, if we figured out what dark matter is, that would be pretty amazing. There are many candidates and some groups claim to have maybe detected it, but once we have a confirmed detection that will be very, very exciting.
So when a supermassive black hole is on the move, like when it is ejected from its home galaxy, what exactly are the effects on everything around it? What is it altering or potentially damaging? Is there any chance of that happening in the Milky Way?
Because of the way gravity works in complex systems like galaxies, supermassive black holes tend to “sink” very quickly to the center of the galaxy (“quickly” = it might only take a few million years), and then they tend to stay there. Kicking them out is hard, but it could happen via an interaction with another supermassive black hole. That should happen when two galaxies collide: they each have a supermassive black hole, each sinks to the center of the merged galaxy, and usually the black holes will themselves merge to make a bigger black hole. But occasionally, one of them gets kicked out instead.
When I said above that black holes aren’t as exotic as most people think, this is an example of what I mean. There’s a supermassive black hole at the center of the Milky Way, but it makes very little difference to us. We’re far enough away that it doesn’t matter at all that it’s a black hole; it just matters that it’s got mass, and it’s part of the overall mass that affects our orbit in the galaxy. So a supermassive black hole moving through a galaxy would pull on things around it, but it would only strongly disrupt the stuff it got quite close to. And since this would likely only happen as a result of a merger with another galaxy, it would just be one more disruption amid the overall destruction caused by the merger itself.
We’re going to merge with the Andromeda galaxy in a couple billion years, which will be quite a show. Galaxies are mostly empty space, so in all likelihood no stars will collide with other stars, but the tidal forces are going to eff both of us up. All the stellar orbits will rearrange; we’ll end up combined into a new galaxy of a completely different shape. That might also cause the black hole(s) to become active, in which case forget what I’ve just said and brace yourself, because active black holes can impact galaxies over long distances.
Is there any chance something cool would happen if you fell into a black hole, or would it just be another hum-drum form of being crushed to death?
Define “cool.” I mean, I don’t think you’d end up in an infinite library where you can communicate in the past with your progeny by spilling books off shelves using the power of love (#NOPE), but also you wouldn’t be crushed to death.
What would happen would be both fascinating and deeply unpleasant. You’d experience a tidal force, the same force that causes tides on Earth, just a lot stronger. Let’s say you fell in feet-first. Your feet would be closer to the center of the black hole, so they’d feel a higher gravitational force, and accelerate faster toward the black hole than your head. So you’d stretch a little, and as you fell you’d stretch further and further. That would be more and more unpleasant, until the moment when you ripped in half, at which point you’d presumably die and thus wouldn’t feel any further pain, which would be for the best, really. You’d continue to stretch, so each of the halves would be stretched into two, and so on and so on, until what used to be your body was just a stream of single particles falling toward the center. That’s called spaghettification. Does that count as cool?
