Interview: Jim Al-Khalili on quantum mechanics, lunar exploration and the challenges facing humanity

BBC Sky at Night Magazine speaks to Professor Jim Al-Khalili about some of the biggest questions in science.

Jim Al-Khalili pictured during his talk at the Bluedot science and music festival, Jodrell Bank, 2019. Credit: Lucas Sinclair

Theoretical physicist, science communicator, television presenter, author of several books and now, sci-fi novelist. Jim Al-Khalili has many strings to his bow.

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BBC Sky at Night Magazine got the chance to pick Prof Al-Khalili’s brains about some of the big issues facing humanity: should humans return to the Moon? Will we ever find a unifying theory that explains how nature works? What are the big challenges that lie ahead, and can science find the answers?

How do you feel about renewed efforts to put human beings back on the surface of the Moon?

I was seven years old when Armstrong and Aldrin landed on the Moon, so I don’t really remember much of it, but it is exciting now that finally half a century later we have not just the US but a number of countries planning for human spaceflight to return to the Moon in the coming years.

I think for a lot of people it’s a puzzle: why? We’ve been to the Moon, we’ve done that, let’s focus on something more exotic.

Actually, I think it is exciting that we’re finally going to get people back on the surface of the Moon, and for lots of different reasons that I think are of interest scientifically; for more ambitious spaceflight further afield; even for developing and testing technologies, or mining and space tourism.

There’s a host of different reasons that make it attractive, exciting, even economically viable, because that’s what’s been the issue in the past: there hasn’t been the political will, but also it’s expensive.

But I think economics now dictate that it is something justifiable.

Do you find it exciting the prospect of using the Moon as a base for travelling to Mars? Do you buy into the ‘humans have to go to Mars’ narrative?

I don’t know if I’d say have to go; we don’t have to do anything! There are plenty of challenges and issues to resolve here on our home planet.

It’s certainly difficult to justify if you say “well we’re spending billions on going to Mars, would that not be better spent tackling the climate crisis on Earth?”

Ok, yes, you can’t argue against that, but it is inevitable that humankind will be a spacefaring species and Mars is the next step.

We don’t have to go, but it’s inevitable that we will and if the technology is there I think we should try it. The Moon is the first stepping stone on that journey.

Which excites you more: the prospect of manned spaceflight or the robotic probes that are already exploring the Solar System?

Certainly over the last decade we have learnt an incredible amount from robotic missions; particularly about the outer Solar System, like the Cassini spacecraft exploring Saturn and its moons.

Or the images that we’ve seen of Pluto, for example. We’re learning a lot and don’t need to send a human out there with a camera to snap photos.

But there’s a limit to what we can learn without human help or intervention. Mars is a good example.

The Mars Curiosity rover is chugging along, scratching the surface and sending us information about the samples that are gathered, but you really need humans there, digging down deep, analysing and carrying out the experiments on the surface of Mars if we are going to answer important questions like “did life once exist on Mars?”

It may be that robots can find the answer to this, but I think that there are many things that, technologically, really have to be done by humans. The two go hand in hand I think.

An artist's concept of NASA astronauts on the surface of the Red Planet. Credit: NASA/JPL-Caltech

What are the questions in physics that you would most like to know the answers to?

There are many big mysteries: what is the nature of dark matter and what is it made of, for example.

But I think if I were on my death bed and someone said “you have a wish, and we can answer some burning question that you have wanted to know” it would have to be knowing the correct interpretation of quantum mechanics.

Quantum mechanics is the most powerful theory in all of physics, describing the subatomic world, and we have a dozen different ways of explaining what the heck is going on down at the subatomic level.

But we don’t know which one is right. Are there parallel universes? Is there an instantaneously interconnected quantum field? Are signals travelling back in time?

There’s weirdness down at the quantum level. I’d like to know which aspect of the weirdness nature actually uses.

It’s the burning question that I keep coming back to now and again throughout my career. I don’t think I’m going to be the person to solve it, but I would like to think it will be solved in my lifetime.

What is quantum mechanics? I think a lot of people, myself included, find it quite difficult to grasp.

One of the founding fathers, the Danish physicist Niels Bohr, said if you’re not astonished by quantum mechanics then you clearly haven’t understood it.

You’re meant to be astonished! People say “I can’t get my head around that” but no-one has got their head around it.

It was developed in the 1920s and it came about because physicists realised that there were phenomena down at the level of atoms and the particles that make up atoms way beyond what we can see with the naked eye, that simply couldn’t be explained with the physics that was known at the time.

The physics that we learned at school that was laid down by people like Galileo and Newton, simply didn’t work when you’re trying to talk about how atoms move.

I’m an optimist despite the political climate, and despite the challenges facing humanity. I think science does have many of the answers.

It’s not the same as how a tennis ball moves through the air. You can describe a tennis ball: how hard you hit it, how much you make it spin, how it’s going to bounce, how it’s going to travel through the air.

If you replace the tennis ball with an atom or an electron, then it behaves very differently.

In the 1920s physicists realised that in order to describe the subatomic world they needed this new mathematical theory; this new type of mechanics that wasn’t Newtonian mechanics, what we now call classic mechanics.

It was a new quantum mechanics based on particles being more ephemeral; more sort of ‘fuzzy’. This is a theory that’s based on probability and chance, uncertainty.

Nothing is solid, nothing is fixed down at the quantum level, it’s very difficult to pin something down.

And yet, mathematically quantum mechanics is incredibly powerful and accurate. Without quantum mechanics we would not have understood a lot of physics and chemistry.

We certainly wouldn’t have semi-conductors and silicon chips, therefore no-one would be reading this interview online because we wouldn’t have electronics.

Most of our modern, technological world is based on quantum mechanics being correct, and yet at its heart it’s fundamentally counter-intuitive: how can an atom be in two places at once? How can something spin clockwise and anti-clockwise simultaneously?

It’s ridiculous! Even saying it sounds ridiculous. And yet that’s how the quantum world behaves.

We have this plethora of different ways of explaining how these things work. We know they do happen, but ‘how’ is another matter. So these are called the ‘interpretations’ of quantum mechanics.

One of the most popular ones is called the ‘many worlds’ interpretation, which says that if you want to measure whether a particle is one place or another, and you find it in one place, the Universe splits in two, in which case another version of you will have found the particle in the other place.

And so there’s an infinite number of parallel realities all co-existing because every time the quantum world is faced with a choice, a reality splits into two.

Werner Heisenberg (left) and Niels Bohr (right), two giants of quantum mechanics in the early 20th century, pictured at the Copenhagen Conference in 1934. Credit: Fermilab, U.S. Department of Energy
Werner Heisenberg (left) and Niels Bohr (right), two giants of quantum mechanics of the early 20th century, pictured at the Copenhagen Conference in 1934. Credit: Fermilab, U.S. Department of Energy

Now, that sounds so much like science fiction nonsense that you think “surely scientists don’t really believe that” and yet many would argue that’s actually the most sensible way of explaining things, because everything else requires further complications and assumptions on top of it.

I don’t know if it’s correct and there are many other interpretations. I’d like to know how it is that the atom can be in two places at once. What is actually going on?

I don’t think we’ve been smart enough yet to figure out the way nature plays its quantum tricks, and I’d like to think that one day we will be.

We’ve tried everything so far. Lots of very smart people have thought very hard about it, but we’re still not there yet.

It sounds rather like how Newtonian physics was challenged by the theory of relativity. Is it within that realm?

Quantum mechanics by the late 1920s developed into what’s called quantum field theory. Quantum field theory then evolved into bigger mathematical structures that were describing the forces of nature.

We ended up with the Standard Model of particle physics, which is essentially a collection of mathematical theories that describe all the the forces of nature, apart from the force of gravity.

Gravity is the odd one out. That’s described by a completely different theory: Einstein’s General Theory of Relativity.

This is another thing to add to the wish-list of physicists! How does the force of gravity fit into the other forces of nature?

We’re looking for a theory of quantum gravity that would connect up quantum mechanics, culminating in the Standard Model with general relativity.

But we don’t know how to do it because they are very different theories: the maths is different, the concepts and the way they describe reality is very different, but we still have hope that one day we’ll find the answer.

Either one has to be tweaked, or the other has to be tweaked, or we ditch both of them and start something else.

They’re both correct, but clearly they can’t be the whole story. There must be some unified picture of reality, ultimately.

You’ve recently released your first novel, Sunfall. Was it difficult to make the leap into fiction?

It’s my first work of fiction and I’m not sure if it will be my last yet, we’ll have to see!

It was a lot harder than I anticipated. It’s a science fiction novel, so it’s near future, hard sci-fi. It was basically the sort of book that I would have liked to have read as a young man.

I grew up on the science fiction of Arthur C Clarke and Isaac Asimov, Larry Niven and Robert Heinlein; classic sci-fi writers of the ‘60s and ‘70s. They painted a picture full of science.

Sunfall is not fantasy; it’s not about a dystopian future where a virus has wiped out humanity and a group of teenagers with super powers are going around killing zombies, which tends to be most of science fiction these days!

I thought “why not try my hand at writing a science fiction thriller? How hard can it be?”

It turns out to actually be very hard and very different from writing non fiction.

Luckily I had an editor at my publishers Transworld, who was incredibly helpful and supportive and prepared to roll up his sleeves and basically teach me the tools of the trade.

Writing a novel is a craft, and you have to learn a lot of those tricks of the trade.

I remember my editor saying, for example, “show don’t tell”. Anyone who’s written fiction will know what that means.

You don’t explicitly spell out how someone’s feeling and someone’s actions, you have to make it come through the narrative more subtly.

On my very first attempt, the comment that came back was “Jim it’s not a physics lecture followed by a line of dialogue followed by another physics lecture.”

Gradually, after the fourth or fifth draft, I got better at it.

I found I was very good at writing the action, page-turning aspect of it. It’s very much a thriller; very much in the vein of the Stephen King school of writing, who is another wonderful author who I’ve always enjoyed reading.

But of course it’s science fiction, so I’ve put a lot of science into it. I enjoyed doing that, and I enjoyed trying to get the science right.

Sunfall is set in 2041, so not too far into the future, and the science we know today is likely to be realised technologically 20 years from now.

One of the advantages for someone like me is that I’m involved in a lot of interdisciplinary research here at the University of Surrey, but also through my science communication work.

Presenting The Life Scientific on Radio 4 means that I have now interviewed almost 200 scientists who are at the top of their game.

It means that I know what is the exciting cutting edge that is going on today, and what the world may well look like tomorrow.

So I feel like I’ve been able to paint quite a realistic picture of what the world would look like, with AI and augmented reality, quantum computers, dark matter and all sorts of goodies like that.

It’s been a tremendous adventure writing the book.

Jim Al-Khalili pictured interviewing Richard Dawkins at the Bluedot festival 2018. (Andrew Benge/Getty Images)
Jim Al-Khalili pictured interviewing Richard Dawkins at the Bluedot festival 2018. (Andrew Benge/Getty Images)

Speaking of future science, what do you think are the biggest challenges facing humanity at the moment, and do you think we genuinely have the ability to solve them?

I’m an optimist despite the political climate in this country today, and indeed the world, and also despite the many challenges that face humanity in the 21st century.

I think science does have many of the answers, and indeed engineering. One of the nice things I’ve taken on recently is I’m a judge on the Queen Elizabeth Prize for Engineering. It’s like the Nobel Prize for engineering.

I get to see just how important engineering technological innovations are if we are going to tackle the biggest problems.

Climate change is I think without doubt the biggest issue facing humanity in my lifetime, and we can see already some of the effects that it’s causing around the world.

But I still think science and engineering can provide a solution, it’s more to do with political will, economics, public acceptability.

It’s not that scientists and engineers don’t know what to do. There are all sorts of ideas, we just have to come together as a species to tackle them.

Climate change is one issue, and there are always things like the threat of pandemics, issues to do with diseases and poverty around the world and dwindling resources.

Science and engineering themselves throw up challenges that we have to be mindful of.

As we develop things like artificial intelligence, for example, we need to be aware of what the implications are, ethically, about that. The same goes for things like genetic engineering.

By and large, I think science is a force for good, provided we put it to good use, and I refuse to be disheartened and disillusioned by some of the problems facing us. I think we will find answers.

If science fiction is your thing, read our guide to the best space movies of all time.

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Iain Todd is BBC Sky at Night Magazine’s Staff Writer.