Quirks & Quarks

Transcending the uncertainty of quantum mechanics in 'Einstein's Unfinished Revolution'

‘What we want is to know what nature is fundamentally like whether we’re around or not’

‘What we want is to know what nature is fundamentally like whether we’re around or not’

Portrait of physicist Albert Einstein sitting in an armchair and smoking a pipe, circa 1932. (Photo by Three Lions/Hulton Archive/Getty Images) (Photo by Three Lions/Hulton Archive/Getty Images)
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Renowned theoretical physicist Lee Smolin from the Perimeter Institute for Theoretical Physics in Waterloo, Ont., is calling for a rewrite of a fundamental theory of physics.

Quantum mechanics, the theory that applies in the atomic and sub-atomic world, is a theory of uncertainty and probability.

A famous example of this is the famous 'Schrödinger's cat' thought experiment. It presents a hypothetical cat in a closed box, with a flask of poison that will be released if a single atom decays in the box. Since the decay of a single atom is, in quantum theory, governed by probability, it's impossible to know if the cat is alive or dead before opening the box.

In fact, according to the dominant interpretation of quantum theory, before the box is opened, the cat may be considered in a superposition of states — both alive and dead.

Quantum theory is incredibly successful. It's stood the test of experiment, and modern technologies from the computer to the cell phone depend on it's accurate (if probabilistic) predictions.  

But for some theoretical physicists, including Smolin, the probabilistic and uncertain nature of quantum theory is unsatisfying. 

(Penguin Random House)

In his new book, Einstein's Unfinished Revolution: The Search for What Lies Beyond the Quantum, Smolin calls for a realist's theory of quantum physics that eliminates the uncertainty in the current theory to get at the true nature of reality.

He thinks that this is what will take us to the next stage of understanding the universe, and allow us to solve fundamental problems in science like what caused the Big Bang and the unified theory of physics

Here's part of his conversation with Quirks & Quarks host Bob McDonald:


This interview has been edited for length and clarity.

Bob McDonald: Your book goes through all the ways physicists have tried to reconcile these issues within Quantum Mechanics. But then you take it a step further. You're calling for a rewrite of the fundamental theories of physics. Why are you calling for that?

Lee Smolin: We want an alternative to quantum mechanics which is a realist theory which describes exactly what's going on and every process and every experiment is not just an algorithm to generate probabilities.

There are a number of proposals for such a theory and I discuss in detail several of them and I come to the conclusion regretfully that these different proposals are not satisfactory.

And so, I say that the situation is that we need to start again with new ideas and new principles and I give an example from my own work of one path to start again that gets to a reformulation of quantum mechanics.

Lee Smolin is a founding faculty member of the Perimeter Institute in Theoretical Physics, Waterloo, Ontario. A theoretical physicist and writer, he has greatly advanced our understanding of space, time and cosmology (Penguin Random House)

BM: In your book, you say there are certain guesses about nature that theorists are willing to bet their careers on. For you, you said it's being a realist, which we've already talked about, but a relationalist. What do you mean by that?

LS: I mean somebody who hypothesizes that the fundamental properties of matter of elementary particles are about relationships with other elementary particles.

The idea that where something is or what time it is doesn't have an absolute meaning but is only defined relative to something else. So you can give your address relative to a street which is defined to be in a particular city, which is on the particular continent, on that particular planet but there's no other way but this relational description of how where you are relates to other objects of giving meaning to where you are.

BM: So what does this mean for the nature of spacetime within the reality of a dynamic universe?

LS: I think it means that space is not fundamental. Space is what we say emergent, it's a property of the bulk of a large scale. It's a way of describing things at a large scale but it's not intrinsically fundamental in exactly the same way that the temperature of the air in this room is not fundamental.

It's really an average description of the energy of motion of all the atoms bouncing about in the room. And similarly, temperature nor pressure are fundamental. They're emergent and they are not part of the more fundamental atomic description.

And in the same way I would posit that space is emergent and there is a more fundamental description of the processes that make up the history of the world, which don't take place in space but are defined by relationships and their dynamics.And these relationships and their existence and their properties are fundamentally what nature is about.

This idea was fundamental to Einstein in constructing his theory of general relativity. And general relativity is the triumph of that relational point of view. I want to extend that viewpoint to atoms and radiation and elementary particles to make a world which is constructed from relationships and nothing but dynamical evolving relationships.

In Einstein's Unfinished Revolution, Lee Smolin brings us a step closer to resolving one of the greatest scientific controversies of our age that Einstein began nearly a century ago. (Photo by Keystone/Hulton Archive/Getty Images)

BM: You say at the end of your book that as you're nearing retirement age you see two paths ahead of you. Do you continue along the path of trying to make sense of quantum mechanics within the existing frameworks or do you create a new path? Dr. Smolin, what's it going to be?

LS: I don't have a choice. My personality pushes me towards satisfying my curiosity about the most fundamental questions.

Two weeks ago, Roger Penrose was here. Roger Penrose is just a little bit short of 90 and is in perfect shape and is continuing to advocate and push forward his attempts to make a fundamental theory of cosmology and space and time, and I'll take Roger as my role model and my inspiration.

We all take a gamble with our careers, and as a scientist you take a gamble on what to work on, what to invest your time and energy and training and expertise in, and you take a gamble in the ideas that you develop.

When I got into this, which was by reading a set of autobiographical notes of Einstein, It was clear to me that I would probably fail. I was 17 and of course I knew I was very unlikely to be able to reproduce Einstein success, but I didn't care. I thought what a wonderful thing to do to spend a life trying to discover the fundamental laws of nature and if I succeed, that's very unlikely, but that would be wonderful.

And even if I don't succeed, I might have the opportunity to spend a lifetime pursuing what I'm most curious about, and adding something to the stockpile of ideas and knowledge that might help some people in the future who would come along and be the ones to solve the problems.

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