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Brian Schmidt: in conversation

For Brian Schmidt, and the rest of us, the universe is expanding. Enzo Amato

Brian Schmidt: in conversation

Professor Brian Schmidt was part of the team that won the 2011 Nobel Prize in Physics “for the discovery of the accelerating expansion of the universe through observations of distant supernovae”. The consequences of the research were, and will continue to be, profound. It marked a major moment in scientific discovery.

The effects of the Nobel Prize win on Schmidt have also been profound. His views on science education – discussed below – now make national news. People who don’t know him look at him differently, “like I’m some movie star”, and the requests on his time have multiplied greatly.

He has gone from “someone who’s a pretty normal person, happy to provide comment and thoughts on almost anything, to suddenly having to take a deep breath, because now whenever I say anything it can end up in the media”.

In a wide-ranging interview, philosopher and science journalist Tim Dean asks Brian Schmidt what it’s like to walk in his shoes.

The universe, as it was

It’s a great pleasure to be chatting to you. I think for the people who are reading this, it might be a bit odd to have an astrophysicist in conversation with a philosopher.

They go hand in hand as near as I can tell.

Well, I do think there was a time, in the maybe more distant past, when the two professions did overlap to a considerable degree. I’m thinking about the Ancient Greeks, who were the first to really attempt to measure the size of the world, the size of the universe.

I’m thinking of Aristarchus and thinking of Eratosthenes, who measured the distance to the moon with surprising accuracy; and the grand endeavour of trying to figure out exactly how big the universe is that we’re in, which is a philosophical question as well as physics question.

Do you see yourself as being part of that tradition – of adding more information to help solve that question in the same way the Greeks were, that Copernicus was, and other astronomers along the way?

Certainly, astronomy is one of the oldest things humanity has done, and I think it’s universal, it crosses culture. Our work of understanding the ultimate fate of the universe or what the past universe is, how the universe works, what’s in it - those are fundamental questions that the Greeks would understand, the Aborigines would understand, everyone understands.

The way we go about answering it, well, that’s maybe different across cultures, but it is one of the big questions - and that’s one of the reasons it’s interesting to me. What’s our place in the universe?

Our conception of the universe has changed radically over the centuries, and it’s even changed dramatically over the last century. Only 100 years ago, the Milky Way was the extent of the known universe. Around about the first part of the 20th century we were starting to get a hint that it was a bit bigger than that.

When you were doing your PhD and moving into your post-doc, in the early 1990s, what did the universe look like back then?

We certainly assumed it was simple, we assumed it had stuff in it which gravity worked more or less by Newton’s laws, but with modifications by general relativity. It was a universe that was expanding, and slowing down.

From a philosophical point of view, it had a horizon, and a horizon is how far we can get information from, because of the speed of light, over the age of the universe.

It had a horizon that was increasing. Forever. The older the universe got, the more and more of the universe we could see. Which is conceptually quite nice.

It was a universe which may or may not have an end, but it really had one of two stories: it was going to exist forever, or it was going to be finite; it was infinite or finite.

That was the universe I went out to embark to measure. Was it story A or was it story B?

When you finished your PhD and started on your research after that, what motivated you? What were the questions that you wanted to answer at that point?

I wasn’t really sure. Right when I finished my PhD, I had measured the expansion rate of the universe, the Hubble Constant as it was known. I got an answer that was reasonable, and couldn’t see how I could improve that any more than I’d done, given the method I had.

So I was searching around. I was very interested in the physics of these exploding stars, but there’s interest and there’s opportunity. It was really a year after I finished - six or seven months after I finished my PhD – that suddenly the opportunity came that I could see that I could measure the past history of the universe.

I never saw that opportunity right after my PhD, because of the technology - it was a futile thing to do. We didn’t have the tools, we didn’t have these Type Ia supernovae, which meant we didn’t have the technology to reliably measure things in the way we needed to.

And those two things appeared to me about a month apart, in February and March of 1994. And I remember first seeing this team in Chile had figured out that these supernovae could be used to measure distances very accurately.

And it was way in excess of anything I conceived - I was very sceptical of these before - because quite frankly they had a reputation that was built on thin air.

The universe, as it might be

All the evidence that we were seeing was that Type Ia supernovae weren’t going to be any good. We had been finding all these weird ones, they weren’t working, and then suddenly they found this key that showed, oh, actually there is a way to make them work.

And when I saw how well they worked - I knew these guys pretty well, I’d used their data for my thesis, it was good stuff - I remember thinking, wow, this was amazing. But I really hadn’t thought about doing the distant universe thing yet because Type Ia supernovae were still not easy to find.

When you’re going to not just ponder, but embark on a fairly lengthy and expensive experiment involving a lot of people, what comes first there? The questions, or the tools? Do the tools inspire the questions, or the other way around?

Well, in this case they were decoupled. The tools that we needed were evolving for other reasons. The question really goes back to the 1930s. The question we were asking - what’s the past fate of the universe - had been known since the 1930s, but it just was not feasible to do it.

So in this case, it was something we’re all taught. I mean I was taught it just like I taught it today in the lecture I gave, and you suddenly have these tools that emerged due to technology, that allow you to ask the questions.

Sometimes there’s a question which you go through if you have enough money, if you are for example looking for the Higgs boson, you spend $10 billion to build the tool. But I had $8,000 - I couldn’t build a purpose-built telescope, I couldn’t do anything.

It was a matter of having the opportunity to do the experiment, rather than the means to spend billions of dollars to develop the experiment. There’s fundamental difference between fundamental discovery, where you really do find something you just didn’t know about, and you’re using tools that are available; and going after a big problem, which is the big science aspect.

Often big science enables the little things, because of course although I had $8,000 I did have access to these $200 million telescopes that had just been built. And they’d been built for other purposes, they’d not been built for my project. But our project has ended up being the most successful biggest thing they’ve done, thus far, but that’s the way science works.

So tell me about that particular project that you embarked on in the mid-90s that eventually led to your Nobel Prize.

We had the means to discover supernovae six or seven billion years in the universe’s past. And we knew, from the theory, that if you could look back that far, the difference between a universe which was infinite and one which was finite could be very large, could be a factor of 30% or 40% in our measurements.

And so then we had presented to us this tool, Type Ia supernovae, that could measure distances to 6% accuracy, so you naturally had an experiment that could be done. We had the new generation of telescopes, and new generation of digital detectors.

The digital detectors allowed us to scan enough of the sky to reliably find these things. We had new computers which were fast enough that we could actually digitally process the data to find the things, and then we had these big telescopes that allowed us to make the measurements we needed to of the objects once we found them.

So that all sort of came together in the middle of 1994. I was down in Chile meeting my colleagues there who had found out how to use these things accurately, and I was a young post-doc, and I said: “We’ve talked to the team that’s figured out how to discover them, I’ve told them all about your work, they’re not listening to us.

"We need to do this experiment ourselves, so it’s done the way we think it should be done. If those guys can find it, I know I can write software to do it. Let’s do it together.”

And they said: “Yes, that’s a great project.” They were planning to eventually do it, but they were in the middle of another project, and so we embarked on this project together.

We recruited a bunch of people because we needed a lot of telescope time and we needed a lot of people to help do the work. So we ended up with a group of 12. A proposal went in at the end of 1994.

I knew during this time I was moving to Australia, I knew I had a job here in Australia that allowed me to do any research I wanted.

They were very supportive. They thought it was an interesting project. So once we got going, it was a matter of writing all that software, and doing all the pieces that needed to be done for such a large experiment. Once I had this idea that this was what I wanted to do, everything else got thrown to the side and this was what I concentrated on – 100% of my efforts.

Standard candles

Going back to talking about measuring the universe, the standard candle is a crucially important concept in that task. The Cepheid Variables were one of the first standard candles that we used for our local area, and the Type Ia supernovae is the standard candle for the very distant universe. What’s so special about a Type Ia supernova?

The reason they’re special is because we can figure out how many watts they emit. And if you’re going to measure a distance, you need to see how bright something is, but you also need to know how bright it is intrinsically, you know how many watts it emits.

So the Type Ia supernovae provided nature’s gift: something that is amazingly bright - five billion times brighter than our sun - yet we could figure out intrinsically how many watts it’s producing to an accuracy of 12%. And that allows us to measure distances to 6%. So they were special because they were both bright, and we could use them as accurately as Cepheids.

So we’re really lucky that nature provided these?

If nature didn’t provide us, we’d have had to scrounge around and find something else, and we are finding things out, turns out we have something even better than a supernova now, something they call a Baryon Acoustic Oscillation, which is a soundwave rippling through space.

In the early universe that soundwave is imprinted in the galaxies. So you can actually see the ripples of sound, left over from the Big Bang, in the galaxies of today, and that provides a way of measuring distances very accurately.

But we only found out about those in the last seven or eight years. So the supernovae were the thing we could use to measure distances.

And they still are a best way to measure distances from about zero to five billion years in the past. These other things are better further away.

The universe, as it is

When it comes to the research that eventually rewarded you with a Nobel Prize, it was the discovery that these very distant Type Ia supernovae were dimmer than we expected them to be. Why did we expect them to be brighter, and what did it mean when we found that they were actually dimmer?

When you measure the expansion rate of the universe, you’re comparing distance to redshift. Redshift tells you how much the universe has stretched, distance tells you how far away you are.

So it’s sort of telling you, if you pull a rubber band, how much stuff has stretched versus the distance. So when you’re looking back over time and the universe is slowing down over time, because of gravity, that means that the distances - things at a given redshift - are closer to each other.

Because the universe was expanding faster in the past, it was actually stretching further - more - in the past. There was more stretch compared to distance.

And so when we looked back and we saw that the objects were fainter at a given redshift, that meant that there was a lot more distance per amount of stretching of the universe.

That meant the universe was expanding slower in the past and it actually had to speed up more recently. So essentially what you’re doing is you’re measuring how fast the universe is expanding now, comparing it to how fast it was expanding in the past.

Effectively we’re able to measure how fast the universe is expanding by measuring distance and redshift.

If we do that nearby, we get Hubble’s Law. That tells us how fast the universe is expanding. We did it a long ways ago by looking at very very distant objects, and it turns out that these objects were further away than we expected, compared to the redshift.

That told us the expansion rate of the universe back in the past, and told us the universe was expanding slower in the past and had sped up over time. And speeding the universe up, making it expand more quickly, well, that requires gravity to push rather than to pull.

So what makes gravity push? In 1998, the answer was: “nothing sensible.” So we had to invent something, and it turns out Einstein had already invented it – the cosmological constant, as he called it, or dark energy as we call it now. So that stuff he invented can make gravity push.

If energy is fundamentally part of the fabric of space, that energy pushes on itself through gravity and makes the universe speed up. So that’s why we were excited by our discovery in 1998.

Changing the game

So before your discovery - we were talking about what the universe looked like back then - I think you used the word “sensible”. It seemed to follow a certain intuitive pattern. The idea of a Big Bang, a rapid expansion, and that expansion is slowing.

In the future - there was some uncertainty about that, but it followed a number of different possible paths which seemed to make some intuitive sense.

Now the idea from a few supernova observations - suddenly the universe goes in a direction we don’t expect it to. It’s accelerating, now it’s exploded, it’s slowed down and then it’s speeding up again. I know people have asked you this before, but was there a Eureka moment?

Because we’re talking about quite a fundamental difference in the how we understand the universe to be, given the results of your work. So was there a point where you sat back and thought: “Hang on a second, the universe is really not like I thought it was going to be.”

Unfortunately the process wasn’t as “Eureka” as it might have been. When we first started seeing the data, I remember just thinking: “Oh jeez, we’ve made a mistake. What have we done wrong?”

And going through each part of the experiment piece by piece, checking it all, and not finding any major mistakes - there were little mistakes but they got fixed. I do remember on the 8th of January 1998 thinking: “Well, Adam Riess - who shared the Nobel Prize with me - and I agree on every single step of this now. All parts of the calculation, exactly.”

And at that point I said: “We’re going to have to tell the world about this.” And I remember thinking: “We’re going to be crucified.” But I was confident our measurements were correct, and I really felt we had done the measurement correctly.

What I was worried about was that somehow astronomy had missed something that would come out, and it probably wouldn’t be our fault per se, but there would be something fundamental that had just not been thought of. But I knew we had to tell people about it.

But did I think it meant the universe was full of something undiscovered? I wasn’t sure. I figured there was sort of a 90% chance that was the answer, but I was still worried something else would pop up.

It wasn’t until the year 2000 that the first measurements of the cosmic microwave background were made, that showed the universe was geometrically flat. That is, it wasn’t a finite universe, it wasn’t an infinite universe – it was sort of on the border.

And it turned out that piece of information, to make it work with our measurements, meant the universe had to be full of this energy, making it expand.

At that point I remember thinking: “I’ll be dammed, we’re right. There’s no way our answer’s wrong now.” So I guess that was my revelation.

Following evidence, wherever it leads

That’s something interesting about the process of science, and about the processes involved in doing science and in the kind of attitudes you have to take to your work.

One of the similarities between science and philosophy, and many other disciplines and other approaches, is a commitment to follow evidence, or in philosophy’s case to follow reason, wherever it leads.

It doesn’t matter if it leads somewhere seemingly absurd, or if it leads somewhere that confirms neither our preconceived notions or our intuitions. When it comes to that point, when you have some evidence that seems to challenge a long-standing view, a very well-entrenched long-standing view, how do you approach that psychologically?

Are you comfortable when you hear about something like dark energy and accelerating expansion - do you accept that readily or are you cautious?

You’d normally be extremely sceptical, and I expected people to be scathing with scepticism. We’ve seen this most recently with the observations shown to be wrong that neutrinos were going faster than the speed of light. But I keep an open mind – the universe is sometimes not like you expect.

You want to see the weight of evidence, you want to see it confirmed, you want to see it looked at this way and that way. And so yeah, science is very slow to accept change unless the evidence is just absolutely overwhelming.

And our measurements in 1998 did not provide overwhelming evidence. They provided evidence that something funny was going on, and we had to get more data and other experiments had to get more data to make it absolutely overwhelming.

I think the evidence now is overwhelming. It turns out it was evidence that fixed a lot of problems in cosmology, so it was accepted more readily than I had expected, and also was done simultaneously by two teams, independent of each other. And that was one of the big things.

Clearly in 1998 you weren’t expecting that it was Nobel Prize-winning research. In 2000, did you think you had changed things quite radically?

Once I realised I was right, I knew it was a big thing to be a part of. And even in 1998, I knew if we were right it was going to be a big thing; it was just the question of whether something unforeseen was going to come up.

The magnitude of the discovery was always pretty apparent to us, but you don’t really think of it in terms of Nobel Prizes, you just don’t.

Life as a Nobel laureate

How has winning the Nobel Prize affected you as a scientist, as a person, and as someone who’s interested in answering questions and is rewarded for doing that?

The Nobel Prize is the one way in which science is truly glamorised on a year-to-year basis, and so ultimately it has glamorised my research. It has made it known to a large fraction of the world, compared to what it had been before.

It has made people who don’t know me look at me differently, like I’m some movie star. It has personally made me incredibly busy – the requests on my time have been a thousand times what they used to be.

I like doing outreach, and I’ve always given lots of talks before the Nobel Prize, but the requests are very broad now, all sorts of stuff, more than I can deal with.

On a personal level it’s weird to be someone who’s a pretty normal person, happy to provide comment and thoughts on almost anything, suddenly having to take a deep breath, because now whenever I say anything it can end up in the media. I had a tweet three weeks ago end up as a whole story in The Australian. That was interesting.

I tweeted it with 24 hours of jet lag when I was in the United States, and that night a newspaper article appeared. You realise you’re on a different regime.

There’s a responsibility. The reality is politicians suddenly listen to me, newspapers suddenly listen to me. I haven’t got any smarter, I haven’t changed, but it has that link-in, and as scientists, the reality is we don’t get listened to much.

We have a lot of insights, but we don’t get listened to much. What I have to do is to try to channel science, since I get to speak, and make sure I say sensible things that represent a consensus and not screw up too much.

Science education in schools

The story of measuring the size of the universe is a perfect example of a grand question that seemed quite simple but is actually very difficult to answer.

It’s been conducted over thousands of years, using every tool that we have in our arsenal, and no one single tool can measure everything. There’s a scaffolding of lots of work by lots of different individuals, using lots of different tools.

The triumph of us now being able to talk with quite a lot of reliability about the size and the age of the universe is a wonderful exemplar of the scientific process. Do you think young people, school students, know of that story, or similar stories of how science works and what it can do?

It depends on how the teachers work. And I think some of them get it. I’m trying to tell that story. When I give a talk I try to talk through the history of how things happened. Of course I’m taking a lot of shortcuts in there as well, but at least I show it really is this knowledge built up from a scaffold.

The way we teach science depends critically right now on the teachers. It’s not something you’re going to teach before six - you teach it in year seven through 12. Really good teachers get that idea across.

But inevitably they’ve been trained as scientists, or related stuff, they have a deep understanding of how science is done, and they have that ability to tell the story.

Some kids get it. If you’ve got a good teacher you’ve got a very good chance of getting it. If you have a mediocre teacher, you don’t, because they just don’t get it themselves.

We need to communicate, and I think we’re in the middle of a revolution in education which is based around the internet.

It’s going to be very interesting to get our head around how we use the internet to do a better job of communicating science.

And not just science - it’s English, it’s humanities, it’s philosophy, it’s the whole gamut of knowledge. We have some possibilities there of using the internet to fix some of our problems, maybe more cheaply.

We need to invest more in teachers, we certainly do, but if we can actually make up for some teaching by doing clever things with the internet and making sure we have some good teachers there, multiplying them and using group - working things together to get people to learn, through these new innovations.

When it comes to science education, it seems there are at least two groups of people we want to reach. One is the future scientists – we want to inspire another generation of people who want to go out and do the hard yards, the experimental and the theoretical work.

But the other is those who are never going to become scientists, and never intend to become scientists – we just want to make scientifically-literate citizens.

Is our education system favouring one over the other? Do we need to make changes in order to appeal to both of those audiences?

I think right now we serve people who want to become scientists reasonably well in most school zones across Australia. Some people are left behind in that. I think the way we teach science for the average citizen can be very bad. We make it easy for them to opt out.

I think we need to be really looking very carefully at the curriculum, and rather than saying: “OK, you’re not interested in science, so just don’t do any,” I would say: “OK, we’re going to offer a stream that isn’t hardcore physics, hardcore chemistry, hardcore biology, but rather a science for everyday use. The science for the normal person.”

I don’t think people should be able to opt out of science, or English, or maths - I think those are fundamental things we need. And so I do think we need to rethink the curriculum.

I think we have, quite frankly, too much selection for classes for people to take. It makes education expensive and ultimately it’s not stuff that’s really at the core.

We need to teach science to be interesting, but not just be memorising facts. The most important part is the scientific process of reasoning and deduction. Getting the idea of evidence and probability and uncertainty – that’s something everyone needs to interact successfully with life these days.

Teaching uncertainty

When we were in Stockholm, we had an interview with the BBC, and the interviewer said: “So guys, if there’s one thing you could teach kids today, what would it be?” We all said the same thing - the concept of uncertainty.

And we all kind of looked around like, “wow, that was kind of weird”, because that wasn’t an obvious thing, but we all had the same idea. That’s part of the scientific process - it’s deductive, but understanding uncertainty. Uncertainty is a huge thing. Almost never are things black and white. There are always probabilities.

And that’s something we need to be teaching, in my opinion, in high school. The idea of how risk and probability goes into real-life problems. And we don’t teach that.

If there was the second stream you were talking about [science for everyday use] I certainly would have taken it. I was very bad at mathematics but I was very interested in science, so I got very poor grades in a lot of science.

If there was a course that would enable me to understand the process without needing to necessarily do the maths behind it, I would have benefited tremendously.

Instead I had to turn to popular science books - I had to turn to Isaac Asimov and others in order to learn. He taught me an enormous amount of science, without me needing to do a single equation. It can be done.

Maths is an important tool as well, and everyone needs a bit of math, so again I would have a stream of mathematics, where you can’t opt out. If it’s balancing a chequebook, doing business, whatever – everyone needs those skills.

They need to be able to do it well, the whole idea of compound interest and how that works, these are important things for people. You need to, as you say, make things reasonable for the average person, at the same time as accommodating the high end.

The internet provides this possibility, because of course you can make quite advanced courses on the internet. You may only have a few kids that want to do it, but that’s OK. If you’re in the middle of Woop Woop now, you can log on and do one of these courses with the other people who are like-minded. What we have done is make everything easier so you can just opt out, and I think that’s wrong.

New horizons

What does the future hold for you now? What are the questions that you’re looking at now? What are some of the things you don’t know about the universe that you’re itching to either have answered or to answer yourself?

Well, we don’t know what dark energy is. We can observe it. I think the answer is likely to come from theorists, but as an observer I can do my best to test things as hard as I can, for some reasonable amount of effort and money. We don’t know what dark matter is.

Lots of questions to be asked there. We may discover it as a particle, maybe not. Then we have real astronomy questions. There are questions that I think are within the realm of answerability in my lifetime. Being able to potentially find the signature of life on another planet, I think, may happen during my lifetime. Maybe not, but that’s the realm we can look at.

After the Big Bang, we have this period where the universe was hot, created all the hydrogen, helium in the universe, and then it cooled off, not much happened. Then suddenly, about 100 million years after the Big Bang, we’re not exactly sure when, black holes, stars and galaxies started to form, and they formed what we see today.

We don’t understand how that happened, and I think that’s a fundamental question.

How did the universe - our part of the universe - get created? That’s another thing I think is going to be looked at in detail in the next ten years, because that’s what the next generation of telescopes are really built to do, to ask those questions.

I think those are some really fundamental questions, but you know, we don’t yet understand how planets formed. We have all these ideas, and they don’t seem to work very well, so by doing observations, watching solar systems other than our own come together at different stages, we should hopefully be able to piece it together. There’s a whole range of other questions out there.

So do you agree - I think it was J. B. S. Haldane who said it – that the universe is not just queerer than we imagined but could be queerer than we can imagine? Or do you think that we’ll eventually figure it out?

I don’t think we’ll ever figure it out. I think we’ll get closer and closer to figuring it out. The universe is a crazy place, there’s no doubt about it. I think we’ve made a good job of understanding a fraction of it.

We certainly know so much more compared to where we were 20 years ago. We are figuring it out, but we’ll never completely figure it out, and the universe is still so big, and so interesting – it’s still a frontier science.

My view is that during my lifetime, it’s still going to be some real fundamental questions we can explain. If you’re doing astronomy, you better be able to explain what you do to your grandma.

If not, you’re not doing the right problems. Because astronomy is a frontier science, and we exist to probe the frontier. When we truly run out of the frontier, we will become a much smaller discipline, like we used to be, and we’ll do other things that are in the frontier stage.