Category: Information theory

I was once chastised by security guard at the Art Institute of Chicago for getting too close to A Sunday Afternoon on the Island of La Grande Jatte, the greatest work by the greatest of the pointillist painters, Georges Seurat. I remember blushing with embarrassment as other patrons flicked their attention to me to take in the barbarian careless enough to endanger one of the world’s most beautiful and important works of art.

I also felt an initial rush of outrage that anyone would think I would harm such a treasure. But then I realized that was indeed too close, that my foot was over the line of the designated safe distance to the masterpiece, that I was indeed the Philistine they took me for. But I was a curious Philistine, looking closely to tease out how he was able to pull off his technique.

Pointillism, Atomism and Digitization

The art movement known as pointillism¹ is the technique of applying small strokes or dots of paint so that from a distance so they visually blend together. Largely invented by Seurat, I think the technique visually demonstrates atomism, which Rovelli associates with certain Greek philosophers but was probably first described by the Vedic sage Aruni back in the 8th century BCE. Aruni proposed the idea that there were “particles too small to be seen [that] mass together into the substances and objects of experience.” 

Seurat aesthetically anticipated not only the atomic and quantum theories but the digital age in which we find ourselves living today, an age in which so many people spend the majority of their waking hours looking at screens of pixels.² We are entranced by pointillism all day long.

In a sense, the idea of a pixelated universe is the topic of both Seurat’s work and Rovelli’s as laid out in Reality Is Not What It Seems: The Journey to Quantum Gravity? If you read the last post (or, better yet, the book itself) you should have at least a general notion of quantum gravity.

But what prospects does the theory have? How might it be supported by scientific evidence, and where might it lead us? Let’s discuss.

Vive la Révolution

Quantum physics was a revolution in physics, but what if Rovelli is right and all of spacetime is quantum? Well, then, the revolution is just beginning. Who really knows what knowledge it could bring us? Might quantum gravity help us better understand understand how to harness gravity itself? What new technologies could be created with it? Rovelli doesn’t discuss possible applications, but I can’t think of any major physics discoveries that didn’t also bring earth-shaking new technologies.

Testing Quantum Gravity

So, how can the theory be tested? One idea is to look for evidence of a “Big Bounce” as opposed to a “Big Bang” in the origins of the universe. According to Einstein’s view of the universe, all of spacetime could be squashed ad infinitum, ultimately leading to the Big Bang. But, that’s not what quantum gravity would predict. Rovelli notes that “if we take quantum mechanics into account, the universe cannot be indefinitely squashed.” And if that’s true, then we wouldn’t get a Big Bang but, rather, a gigantic rebound that he refers to as the Big Bounce.

So, how does one test that? Well, one can look at the statistical distribution of the fluctuations of cosmic radiation. That should provide evidence of the Big Bounce. In addition, according to Rovelli, “cosmic gravitational background radiation must also exist–older than the electromagnetic one, because gravitational waves are disturbed less by matter than electromagnetic ones and were able to travel undisturbed even when the universe was too dense to let electromagnetic waves pass.”

There’s also the prediction by the quantum gravity theory that black holes are not ultimately stable because the matter inside them cannot be squeezed into a single point of infinite density. Rather, at some point, the black hole explodes (like a miniature Big Bounce). If we can locate some exploding black holes in the universe, then we have more evidence of quantum gravity.

So, basically, if we find that super dense stuff is bouncing and rebounding in the universe, the quantum gravity folks might be right. If not, well, at least we’ll have evidence the theory is wrong and we can consider the other theories that have been, and surely will be, conjured up by the endlessly creative theoretical physicists.

If the quantum gravity champions do turn out to be right, then one of the side effects will be that the infinity goes away. Or, at least, physicists are a lot less likely to get infinity as the answer when they run certain calculations based on general relativity theory. The universe itself becomes “a wide sea, but a finite one.”

Bit by Bit, Information Becomes Reality

But don’t assume that, just because the universe might be finite, it doesn’t stay weird. In fact, it may start seeming weirder than ever if humanity succeeds in merging quantum mechanics information theory not only with the theory of relativity but with information theory.

First conceived by engineer and mathematician Claude Shannon in the mid-20th century, information theory assumes that information “is the measure of the number of possible alternatives for something.”

It was Shannon who popularized the word “bit” to mean a unit of information. He used it in his seminal 1948 paper “A Mathematical Theory of Communication,” and he attributed the origin to a Bell Labs memo written John W. Tukey, who used bit as an acronym of “binary information digit.”

Rovelli explains, “When I know at roulette that a red number has come up rather than a black, I have one ‘bit’ of information; when I know that a red even number has won, I have two bits of information…”

I won’t belabor this because information theory gets pretty complicated and Rovelli doesn’t go too deeply into it. To get a better but non-technical understanding, I recommend reading The Information: A History, a Theory, a Flood by James Gleick. I read it several years ago and hope to give it a second read over the next several months.

Anyway, it was John Wheeler, the father of quantum gravity, who was “the first to realize that the notion of information was fundamental to the understanding of quantum reality.” He coined the phrase “from it to bit,” meaning that the universe is ultimately made up of information.

Rovelli writes:

Information…is ubiquitous throughout the universe. I believe that in order to understand reality, we have to keep in mind that reality is this network of relations, of reciprocal information, that weaves the world. We slice up the reality surrounding into “objects.” But reality is not made up of discrete objects. It is a variable flux.

Although Rovelli has one more chapter on the scientific method, I think this is the better place to wrap up a post on a blog called The Reticulum. Let’s sum up: Reality is a network of relations among bits of information in a variable flux.³

I don’t know if that’s a true description of our underlying reality. But it does feel familiar: flux and foam, bits and bytes, indeterminacy and statistical spins. Even if quantum gravity doesn’t work out as epistemology, it still captures much of the essence of our baffling, vertiginous and often wondrous modern lives.

1 The word pixel, by the way, is a portmanteau of "picture element," which is the smallest addressable and controllable element of a picture represented on a digital screen.

2 As visionary as the technique was, the term "pointillism" was actually coined by art critics in the late 1880s to ridicule Seurat and the other members of the art movement. But the artists, as they so often do vis-a-vis critics, got the last laugh. Today, the term is regarded as describing one of the great movements of neo-impressionism.

3 Which makes me think, of course, of Doc Brown's famous "flux capacitor."

Feature image: A Sunday Afternoon on the Island of La Grande Jatte by George Seurat: https://commons.wikimedia.org/wiki/File:A_Sunday_on_La_Grande_Jatte,_Georges_Seurat,_1884.jpg