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Is Reality Digital or Analog? Read the Essays and Cast your Vote

The views expressed are those of the author and are not necessarily those of Scientific American.

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FQXi essay contest logoLast week, the Foundation Questions Institute announced the winners of its third essay contest, which Scientific American co-sponsored. (I helped to decide on the question, judge the essays and hand out the awards at the World Science Festival in New York City.) The essay question was, "Is Reality Digital or Analog?" Is nature, at root, continuous or discretized? You can make a powerful case for either option. Or both options. Or neither. A venerable tradition in essay-writing is to question the question.

In fact, whenever I tell people about the contest, many object to the word "reality." What does it even mean? Will we humans ever be able to grasp it? The deeper that physicists dive, the more the concept of reality keeps swimming away from them. Leonard Susskind suggests in an interview in our August issue that reality is inherently slithery. Black holes, in particular, introduce an unavoidable ambiguity into our description of nature. That said, we have no choice but to keep swimming after it. I personally am optimistic that one day we’ll succeed. (I wrote a whole book on that premise.) The progress physics has made over the centuries makes a strong case that the amazing complexity of the natural world arises from the repeated application of a few simple rules that are within our power to apprehend.

Essay contests have a distinguished history in physics to gain traction on slippery problems, outside the strictures of the standard journal paper. They also broaden the pool of intellectual talent. A total of 161 people from 30 countries entered this contest, and 70 percent of them were not academic physicists or philosophers. The awards reflected a combination of public ratings and judge deliberations. I would say that all the essays that placed deserve reading. They don’t provide watertight arguments—I daresay I found something to object to in nearly all of them—but do get you thinking. Let me offer a sense of the range of ideas.

Living in the age of bits and bytes, we tend to think reality must be digital, so some of my favorite essays were ones that took the contrary point of view that the world is really analog.

David Tong of the University of Cambridge and Ken Wharton of San Jose State University did just that. Quantum theory is usually thought of as discrete; after all, that’s what the word "quantum" connotes. But its equations are actually formulated in terms of continuous quantities. Discrete quantities appear only when a system is constrained in some way, just as a guitar string produces certain tones because it is pinned down at both ends. For instance, the stair-step energy levels of atoms reflect the fact that atoms are held together by a balance of forces.

Partisans of the digital view argue that even the continuous quantities are, on closer inspection, discrete: they lie on a grid whose elements are spaced so tightly together that they give the illusion of a continuum, like the pixels on an iPhone 4 screen. But Tong observed that at least one feature of nature really does seem to require a true continuum: the fact that elementary particles of matter come in distinct left- and right-handed versions. And Wharton, by considering the varieties of constraints we can impose on continuous quantum systems, offered a provocative interpretation of one of the most important concepts in physics, the principle of least action.

That said, the digital view has strong appeal. The main evidence is that quantum mechanics, when applied to gravity, implies that distance and duration come in smallest possible units. Susskind’s work on black holes showed that quantities such as energy and entropy are discretized, too. True, space and time can’t be anything so straightforward as a grid of pixels, because such a grid would spoil the symmetries we observe in nature. Instead, discreteness suggests to many physicists that space and time are derivative concepts that emerge from some deeper level of reality. A number of essays reviewed the solutions proposed by mainstream schools of thought, including string theory (Moshe Rozali of the University of British Columbia and Philip Gibbs, who was trained as a physicist and now works as a software engineer) and loop quantum gravity (Daniele Oriti of the Max Planck Institute for Gravitational Physics), as well as dark-horse candidates for a deep theory of nature, such as Stephen Adler’s noncommutative matrix model (Tejinder Singh of the Tata Institute of Fundamental Research in Mumbai) and the proposition that the world is a big computer (Giacomo Mauro D’Ariano of the University of Pavia, among other entrants).

Finally, some of the best essays approached the discrete-vs.-analog dilemma in a fresh way. Jarmo Mäkelä of Vaasa University in Finland imagined a dialogue with Isaac Newton in which he described how to count the possible discrete internal states of a black hole—a quantity known as the partition function, which in turn defines the hole’s thermodynamic properties. Tobias Fritz of the Institute of Photonic Sciences in Barcelona proposed studying graphene as an analogue to quantum gravity. Dean Rickles of the University of Sydney and Thomas McFarlane, a mathematician-turned-patent-agent, suggested that our conceptual and experimental tools bias us toward discrete models of reality.

After you’ve had a chance to read some of the essays, cast your vote in our online poll below!

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  1. 1. Neil Bee 5:20 pm 06/14/2011

    My Essay was in this FQXi contest (under "Neil Bates" instead of this commenting handle), but didn’t win a prize. I’m still grateful for the chance to contribute, and received many interesting and supportive comments. My essay was one of a few to propose experiments and not just engage in theoretical debate. I offered a way to test the proposition that decoherence converts a superposition into a mixture, in a way generally not though possible before. Interested readers can find my essay at

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  2. 2. imipak 6:10 pm 06/14/2011

    The argument that QM uses terms that are continuous makes the assumption that continuous terms exist. If reality (by this, I’m including space, time and any higher dimensions required) is discrete, then it is impossible to compose an equation that has a continuous term.

    @Neil: A fascinating essay and whilst I disagree with your conclusions, I consider the framing of experiments to be absolutely critical in science and found yours to be excellently framed and designed. I’m also a strong supporter of decompartmentalism, which I see you are.

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  3. 3. maevie 7:29 am 06/15/2011

    "A total of 161 people from 30 countries entered this contest, and 70 percent of them were not academic physicists or philosophers. The awards reflected a combination of public ratings and judge deliberations. I would say that all the essays that placed deserve reading."

    I’m not sure what the point is of saying that 70% were not academic physicists or philosophers, when, according to the bios on the essay page, all of the ones that placed are.

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  4. 4. gmusser 11:22 am 06/15/2011

    Three reasons: (1) It shows the widespread interest in the topic. (2) A couple of people who placed *are* independent researchers. (3) Even those who didn’t place or win had their essays read by a huge number of people. The main point of the essay contest wasn’t to choose winners, but to provide a venue for new ideas outside the strictures of scientific journal publishing.

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  5. 5. Neil Bee 11:26 am 06/15/2011

    Maevie, from what I heard at FQXi discussion pages, some of the winning essays were written by non-professionals. That may include those with full education like PhD in physics, but currently unaffiliated. I said there should be an explicit effort to find and reward good amateur papers, as well as a different way to rate essays in general. The community rating system (grades given by the contributors to each other!) is flawed. There is interference in the motivation to give a good grade to someone else, because that hurts your own relative standing. Experts should have gone through the papers and looked for significant accomplishments such as having proposed a practical experiment to test differing theories.

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  6. 6. Wilhelmus de Wilde 12:07 pm 06/15/2011

    Thank you George for the constructive article on the contest.
    As a non professional it was for me a great chance to participate my ideas with so much other (non)professional very interested people, you know once an idea has come up in your mind, first thought is :"this is impossible it is to easy, why nobody else thinks about this, I must be mad", once accepted and being read and discussed with others who have also constructive and new proposals to make, you understand that we have the chance to go on together and perhaps we will find new ways to explain "part" of our "reality" or better "realities". if interested please read and react on my essay :


    keep on thinking

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  7. 7. maevie 12:13 pm 06/15/2011

    "The main point of the essay contest wasn’t to choose winners, but to provide a venue for new ideas outside the strictures of scientific journal publishing."

    But to me, by choosing a (rather large) shortlist of top essays, it’s suggesting that all the other ideas weren’t up to scratch. And even if a couple of the ranked papers were from non-professionals/independents, that means that the overwhelming number of non-ranked papers were from non-professionals. I’ll admit that my method for saying whether they were pros was looking for doctorates, my experience of academia would place anyone with a PhD as professional, due to the necessary years spent within ‘the establishment’.

    I guess my point is that none of the excellent ideas/essays appear to have come from non-traditional sources, armchair philosophers etc. That’s not necessarily a criticism (the topic leans towards cutting edge physics, after all), I just felt that pointing out the breadth of entries seemed a tad disingenuous.

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  8. 8. Neil Bee 1:30 pm 06/15/2011

    Maevie, I don’t know why you keep referring to the excellent ideas/essays as being logically identifiable with those that had the highest community ratings. Maybe you meant to put the former in quote marks. Don’t you see the flaw in having a rating system like that? The top CR was only 5.4/10! If most of the community (rem, the essay submitters!) were amateurs, then their rating judgment would be suspect too, wouldn’t it? Sure, the top CR set was then further judged by an expert panel, but they weren’t offered (true?) the remaining papers as a proper check on the CR system.

    If professional judgment had been applied all along, then for example papers proposing actual experiments (there were only a few) would have scored highly (in general, they didn’t.)

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  9. 9. ocjim0 4:15 pm 06/16/2011

    I also participated in this contest as a non-professional ( with a background quite alien to physics — computers, cost analysis, teaching, and economics, but with a fascination in cosmology. I wonder if judges found any special commendations for non-professionals. I saw none that met the criteria:
    Judging panel special commendation prizes for non-professional and/or non-academic entrants (up to 2): US$1000

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  10. 10. solspot 6:36 pm 06/17/2011

    Anyone who considered entering the essay contest must admit that the credentials of many entrants and past winners were rather intimidating. These are world-class teachers and writers; I mean Julian Barbour… really?!

    But isn’t that the point?! The contest got the best minds debating in a public forum, using clear, concise language; and you don’t even have to pay outrageous tuition or subscription prices! It’s like the world series for free. Who can complain about that? All that’s missing is free beer and pretzels.

    Thanks George and SciAm. It was pure enjoyment, and I didn’t see a single digression into antireligion rants. Marvelous!

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  11. 11. verdai 8:34 pm 06/17/2011

    how can you talk about essays, when truly trying to consider this question?
    the answer is one word.

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  12. 12. michaeltdeans 8:52 pm 06/17/2011

    My entry shows that cosmology and particle physics, the limits of human perception are determined by the view afforded by a novel brain model based on a structure for ‘the chip in the brain’, and suggested ways to test it. We conceive and share an analogue reality but only perceive a digital version.
    Voting by contestants biased the selection of winners, just as affiliations, referees and citations bias editors. My doctoral thesis was dismissed by ‘ideas are not knowledge’, research proposals usually by ‘not my subject’.
    Unless science and its principles are accepted by the public and used by organizations, poverty, disease and pollution threaten survival. I offer hope. What is ‘supsicious’ about this comment?

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