杏吧原创

Are you enjoying the current popularity of physics that鈥檚 come as a result of discoveries like the Higgs boson and gravitational waves?

It鈥檚 interesting, because physicists sort of ruled the 20th century with quantum mechanics, the atomic bomb and all sorts of technologies. We had the most political power and intellectual heft. Now the biologists are stealing that from us. Biology is advancing enormously quickly, and has a much more direct impact on our lives. But such advances 鈥� gene editing, for example 鈥� can be double-edged swords. In a sense, this works in favour of physics: the kinds of discoveries we鈥檙e making now don鈥檛 have immediate implications for technology or our everyday lives. No one鈥檚 worried about how the Higgs boson or gravitational waves are going to be used 鈥� they鈥檙e just really cool.

These physics breakthroughs have come from proving mathematical theorems. Should we continue to use maths to guide research?

It鈥檚 not just that mathematics is helpful in understanding nature, it鈥檚 the scientific methodology too. The bigger point is that these things illustrate the knowability of our world. There鈥檚 a quiet debate between people who think nature is fundamentally mysterious versus those who think it is fundamentally intelligible. These kinds of discoveries remind us is that our puny little brains have the power to make amazing predictions about far away and very difficult-to-access aspects of the natural universe.

So what鈥檚 next in this 鈥渄ecade of discovery鈥�?

It鈥檚 impossible to say. We could find proof of cosmic inflation in the early universe, discover dark matter and find some particle that鈥檚 outside the standard model of physics. Any of those could happen in the next two years. We also have a hint from the LHC that they鈥檝e found a new particle. I鈥檓 not on board with that yet. I would give it less than a 50 per cent chance of being right, but more than a 10 per cent chance, so that鈥檚 still pretty impressive. Then again, I鈥檓 very bad at predicting the future.

A hundred years passed between the theory of gravitational waves and their discovery. Do we need to give today鈥檚 frontier ideas more time?

Absolutely. There鈥檚 a small part of the human intellectual portfolio devoted to these big, ambitious questions, and you have to let the people who devote themselves to tackling them take their time to work it out. The discovery of gravitational waves by the LIGO collaboration is incredibly impressive for so many reasons: it鈥檚 not just the number of people, but also the number of years it took.

People started taking the detection of gravitational waves seriously in the 1980s and they knew before they built the first gravitational wave observatory that it probably wouldn鈥檛 be sensitive enough to see anything 鈥� and indeed it didn鈥檛.

I would give infinite credit to the visionaries who knew this stuff but would not give up, who devoted their lives to making it happen.

In the absence of experiments to test theoretical ideas, how do you avoid spending decades on something that ends up being fruitless?

You can鈥檛. For example, I鈥檓 going to a meeting this summer at which some great minds are going to debate whether or not cosmology has lost its way by thinking about the multiverse, falsifiability and things like that. I鈥檓 working a lot on quantum gravity now, and the foundations of quantum mechanics. I think we鈥檙e discovering something about how space-time emerged, but maybe what I鈥檓 doing will all turn out to be wrong.

Is the possibility of having wasted your time difficult to live with?

It can be, but I鈥檓 more excited about my own research than I鈥檝e ever been. In modern cosmology we鈥檙e reaching a point where it matters which of the you favour 鈥� Copenhagen versus Everett鈥檚 many worlds, for example 鈥� and that鈥檚 enormously exciting. We need to think about the right way to think about quantum mechanics if we鈥檙e going to understand, for example, how space-time emerges. What look from the outside like fuzzy, philosophical questions about the nature of reality, which we can debate for years and years, will suddenly become enormously relevant. They will become sharp tools for answering deep questions about cosmology and particle physics. For me, the many-worlds interpretation is actually very simple, precise and compact.

How do your peers react when you say that your philosophical position matters when you鈥檙e doing cosmology?

A lot of them just roll their eyes. They鈥檙e like, 鈥淩eally? I thought we鈥檇 got rid of that kind of stuff!鈥� It鈥檚 put me outside the mainstream, but I鈥檓 OK with that.

Your book, , roams far beyond cosmology and physics, into consciousness, philosophy and the meaning of life. What do you hope to achieve?

Well, this is the book that should accompany the Gideons Bible in all hotel rooms in the world 鈥� that would be a nice achievement!

Seriously, I think a better achievement would be if it鈥檚 read by some people who were curious but hadn鈥檛 made up their minds about how the world works at a fundamental level. They could read a book like this and think, 鈥淵es, this picture does kind of hold together, I should think about it more deeply and learn more about it鈥�.

鈥淢y view has put me outside the mainstream, but I鈥檓 OK with that鈥�

Would you like your book to encourage the next Einstein?

I don鈥檛 like to talk about the next Einstein: the large majority of theoretical work is collaborative these days. But I certainly have no fear that our intellectual resources are drying up. The very bright young people coming through know an enormous amount, and are intellectually extremely lively and willing to dive deeply into the harder questions.

Do you think artificial intelligence could do a better job of developing physics than humans are capable of?

Why not? The brain is just a certain collection of atoms and particles bumping together according to the laws of physics, so there鈥檚 no reason at all why some other collections of atoms and particles bumping together couldn鈥檛 come up with equally good thoughts as my brain can 鈥� or much better thoughts.

We already get a lot of help from computers in solving equations. But that鈥檚 not what we get paid for: as a theoretical physicist it鈥檚 deciding which equations to look at that鈥檚 the real difficulty. That鈥檚 a whole other level of creativity and reasoning that we are very far from being able to implement in an artificial intelligence.

So your career is safe from AI?

My career, yes. But I wouldn鈥檛 say that about the next generation.

This article appeared in print under the headline 鈥淚t鈥檚 mind-blowing what our puny brains can do鈥�