quantum physics Archives

Nothing But the Reticulum Exists

No Thing and Nothing

The other day I came across an interview with theoretical physicist and science writer Carlos Rovelli. He was describing ideas from the relational quantum mechanics theory.

Upon a quick scan, one quote caught my eye: “the world is not a set of things with properties.”

Okay, professor. I’ll bite. What is the world?

What’s Interacting?

“The world is a network of interactions,” he states.

Hmm, so, if there are no things with properties, what’s doing all that interacting?

Well, that’s the thing (or, I guess, the nothing?). There’s only the interacting. Nothing has properties until it interacts with something else.

Pretty Zen, right? Hold onto your hat. You ain’t seen nothing yet. Or, um, maybe you have?

Describing relational quantum mechanics, he states, “The idea is that what quantum theory is teaching us is that we should not think that the properties of something (for instance the kicked ball) are always defined. Rather, properties are just the way something affects something else. So, the ball has literally no properties–not even a position–until it affects something, the glass of the windows, for instance.”

Note the word “literally” here. This left me with oh so many questions, especially when he talks about objects. Can there even be objects? So what is an object?

Turns out an object is “the ensemble of the ways in which it affects other objects around itself. An object exists reflected in everything else.”

Got that? No objects unless they interact with other objects. But if there are no objects to start with, where do the other objects come from?

I know some of this is just the inability of language to capture difficult-to-express ideas about quantum mechanics.

But still…

Damn it!

Forced to Read Rovelli (Again)

Once I got to that point in the article point, I knew he had me. I had gone and interacted with his ideas. I could have avoided them. I could have become a human quantum eraser of Rovelli readings.

But no. The ideas and I had interacted and so we both took on properties, I guess. I was then forced to read his next damned book.

Suddenly, thanks to the instant gratification allure of the Kindle, I was reading Hegoland: Making Sense of the Quantum Revolution. After providing a few character sketches of the originators of quantum theory (Heisenberg, Bohr, Jordan and Dirac) and the key contributions of Schrodenger (who disconcertedly turns out to be a pedophile?), Rovelli quickly outlines the basics of quantum theory, jumps into the famously bizarre implications of the double-slit experiment, and briefly outlines various interpretations of quantum theory, with a rhetorical eye on gently undermining them.

But this is all appetizer stuff, preparing readers for the main course: the relational interpretation of quantum physical.

Rovelli’s Wrought Relationships

Let’s back up a sec. What exactly is the relational quantum mechanics (RQM) interpretation of quantum mechanics? Well, look at it like a game of poker.

You remember how Einstein broke broke 19th-century physics when he said the space and time were only relative rather than absolute concepts?

Well, Rovelli ups the ante on the relativity concept, basically going all in. It’s not only time and space that are relative. It’s everything in the whole of creation!

You Are the Eyes of the Universe

A key part of the original idea is that quantum systems are dependent on observers. That is, the state of the system boils down to a relationship between the observer and the heretofore mentioned system.

Confused? Me too.

Are the observers only conscious beings? Are the ball and window observers unto themselves? That is, do the ball and widow become “real” and interact even if I don’t see them do so, or at least see the outcome (that is, the broken window)?

Reality Is Literally Relative

In Hegoland, Rovelli tries to explain his point of view:

What quantum theory describes…is the way in which one part of nature manifests itself to any other single part of nature….The world that we know, that relates to us, that interests us, what we call “reality,” is the vast web of interacting entities, of which we are a part, that manifest themselves by interacting with each other. It is with this web that we are dealing.

One thing he does try to clear up is the role of the observer, saying that “any interaction between two physical objects can be seen as an observation.” So, I guess that we don’t need a person to see the interaction between a ball and window. They are both observers so their interactions make them take on their respective properties.

At least, I think that’s what he’s saying.

But it’s all relative. For you, a fact may be real yet still not be real for me. That’s the real mind-bender in all this.

The fact that some properties exist only with respect to something else should not overly surprise us. We already knew as much. Speed, for example, is a property that an object has relative to another object. Speed does not exist without being anchored (implicitly or explicitly) to something else. It is a relation between two entities. The discovery of quantum theory is only slightly more radical: it is the discovery that all the properties (variables) of all objects are relational, just as in the case of speed.

The Nodes Are the Links?

According to conventional wisdom, networks are made up of nodes and links, with nodes being connecting points joined with other connecting points via those links. Rovelli writes, “Objects are such only with respect to other objects, they are nodes where bridges meet.”

So, in his view, the links between the nodes only exist when the nodes intersect somehow. I think. So….the links don’t exist and then suddenly they do when the nonexistent objects intersect.

Or, something like that…

Part of my confusion is the fact that objects seldom if ever exist in a vacuum. The ball that’s flying toward the window is, as it travels, intersecting with air molecules, photons, water vapor, and so much more. Are all these things “observers” in Rovelli’s conceptualization?

I think so.

If I’ve got this right, it is the intersection of two no-things that causes something to exist. But then he states, “Entanglement is not a dance for two partners, it is a dance for three.”

The Mysterious Third Dancer

Who or what is the third dancer?

It’s what he refers to as a correlation. That is, anytime there is an interaction between two things, there’s a correlation between them, which he also refers to as an entanglement. Is this related to spooky-action-at-a-distance entanglement? He doesn’t say.

Here’s how he defines it: “Entanglement…is none other than the external perspective on the very relations that weave reality: the manifestation of one object to another, in the course of an interaction, in which the properties of the objects become actual.”

So, I see a butterfly and, presto, the butterfly and I are entangled. Our reality is the product of that entanglement. Sure, we may have already been entangled with other stuff. For example, the butterfly may have already been entangled with a flower in my neighbor’s garden and I may have already been entangled with my sneakers (among other things) but the butterfly and I literally don’t exist for one another until there’s an entanglement.

At that point, I guess, my sneakers are entangled with me, which is entangled with the butterfly. Am I entangled with the flower on which the butterfly landed before I saw it? Rovelli leaves me guessing on that score.

Whence Lies Objectivity?

You may be asking yourself, “If the butterfly didn’t exist for you until you interacted with it, then why, once I too have seen the butterfly, do you and I agree on its characteristics?”

Good question.

He tries to answer it.

If I know that you have looked at the butterfly’s wings, and you tell me that they were blue, I know that if I look at them I will see them as blue: this is what the theory predicts, despite the fact that properties are relative [his emphasis]. The fragmentation of points of view, the multiplicity of perspective opened up by the fact that properties are only relative, is repaired, made coherent, by this consistency, which is an intrinsic part of the grammar of the theory. This consistency is the basis of the intersubjectivity of our communal vision of the world.

The Mind of God

I don’t know how things that don’t exist (or, at least, don’t have properties) can interact with one another. If he explains that, I somehow missed it.

Maybe groups of realities exist (for example, one with a butterfly and a flower and another with myself and my sneakers) in which all the nodes are interacting with one another. Then somebody (let’s say the butterfly) who has been made real in one reality (by virtue of its interactions) is able to interact with somebody (let’s say me) from a separate reality because of some clash between group/interaction-based realities.

Uh-huh. Even I don’t quite know what that means. I think the holes in Rovelli’s narrative leave me guessing.

Are we all just conceits in the mind of God, with no reality of our own?

Empty Teachings

His ideas also touch on our sense of self. That is, we do not exist in ourselves. Rather, we are made up of a vast reticulum of phenomena, each link and node dependent on others.

Rovelli tries to elucidate further by delving into the ideas of Nāgārjuna, an Indian Mahāyāna Buddhist philosopher who wrote The Fundamental Wisdom of the Middle Way in the second century CE. “The central thesis of Nāgārjuna’s book,” Rovelli writes, “is simply that there is nothing that exists in itself independently from something else. The resonance with quantum physics is immediate.”

(Well, we should note that the resonance is particularly with his theory of quantum physics, but perhaps it’s churlish to point that out.)

The absence of some core, independent entity is known as śūnyatā, which tends to be translated as “emptiness.” So everything, including you and I, are part of this emptiness. He explains:

[L]ooking at a star, do I exist? No, not even I. So who is observing the star? No one, says Nāgārjuna. To see a star is a component of that set of interactions that I conventionally call my “self.”

Networks In and Out

Honestly, I can’t tell if we are literally or metaphorically discussing networks here, but it is interesting to think about the connections between our brains, our physical selves, and our quantum existence.

Our brains are networks, with our sense of self largely being emergent out the electrochemical patterns of neurons. Likewise, the rest of our physical selves are emergent from complex adaptive systems. Now, if Rovelli is on the right track, the whole of the universe is a constantly shifting and flowing network of realities. Reality is only seemingly objective. It is actually contingent and relative.

Everything else is emptiness.

I don’t know if that’s the truth of it, but so sayeth the scholar-saint physicist philosopher Carlos Rovelli. Or, at least, that’s the reality I’ve taken away from our interaction.

How it strikes you is no doubt destined to be different. Still, though our realities must be unique, we are now theoretically entangled: you, me, Rovelli and his thousands of other readers. Luckily, however, emptiness is everywhere, so none of us needs to feel the least crowded. Feel free to stretch out and ponder on your own.

Namaste.

Entangled in Quantum Networks

Tribbles, No; Entanglement, Yes

You’ve heard of quantum entanglement and maybe even quantum networks, if only in the context of Star Trekian jargon-laden sci-fi expositions like those spouted by Lieutenant Commander Data.

Unlike tribbles and Klingons, however, quantum entanglement is unnervingly real. That is, you have two or more particles that are tangled up in such a way that, even when they’re separated by a long distance, the quantum state of one of them is somehow effected by or reflected in the states of the others.

Weird and a kind of spooky, right? Which is why Einstein dubbed it, with a degree of mockery since he wasn’t quite buying the reality of it, “spooky action at a distance.” Since then, of course, entanglement has been tested many times. At this point, it’s no longer a theory but a practical fact, spooky or no.

Entangling the Big, Hairy Stuff

But what scientists have not done as often is apply quantum entanglement to big stuff: you know, like your hair.

Some recent experiments have worked with two aluminum “drums” that are huge by comparison to subatomic particles: the size of a fifth of a human hair. That is, 20 micrometers wide by 14 micrometers long and 100 nanometers thick, weighing in a whopping 70 picograms (okay, so small, but still macroscopic).

quantum networks — *Credit: J. Teufel/NIST*

ScienceAlert describes the process as follows: “Researchers vibrated the tiny drum membranes using microwave photons and kept them in a synchronized state in terms of their position and velocities. To prevent outside interference, a common problem with quantum states, the drums were cooled, entangled, and measured in separate stages while inside a cryogenically chilled enclosure. The states of the drums are then encoded in a reflected microwave field that works in a similar way to radar.”

The experimenters got the drums to vibrate in an opposite phase to one another, indicating a collective quantum motion, said physicist Laure Mercier de Lepinay, from Aalto University in Finland.

“To verify that entanglement is present, we do a statistical test called an ‘entanglement witness,’’’ NIST theorist Scott Glancy said. “We observe correlations between the drums’ positions and momentums, and if those correlations are stronger than can be produced by classical physics, we know the drums must have been entangled.”

John Teufel, a physicist at NIST and a co-author of one of the papers on this topic, said, “These two drums don’t talk to each other at all, mechanically. The microwaves serve as the intermediary that lets them talk to each other. And the hard part is to make sure they talk to each other strongly without anybody else in the universe getting information about them.”

So, Take That, Heisenberg!

This is clearly cool on multiple levels. First, of course, quantum entanglement at the macroscopic level! What? Is that a thing?

Why, yes. Yes it is. In fact, this isn’t the first time it’s happened.

But, second, this time physicists worked the system in order to (sort of) get around the impossibility of measuring both position and momentum when investigating quantum states.

Glancy states, “The radar signals measure position and momentum simultaneously, but the Heisenberg uncertainty principle says that this can’t be done with perfect accuracy. Therefore, we pay a cost of extra randomness in our measurements. We manage that uncertainty by collecting a large data set and correcting for the uncertainty during our statistical analysis.”

Tap into Your Quantum Network

The concept of a quantum network is, of course, like catnip to people interested in reticula. In the future such networks could “facilitate the transmission of information in the form of quantum bits, also called qubits, between physically separated quantum processors.”

For now, these quantum networks are mostly fiction, but they potentially have a lot of communication and computation applications. One is that they become the backbone of unhackable computer networks. In fact, Mara Johnson-Groh writes that it’s already the case that “basic quantum communications called quantum key distributions are helping secure transmissions made over short distances.”

Johnson-Groh predicts that “quantum networks will be important in scientific sensing first” and highlights the idea of optical telescopes from all over the world connected via a quantum network. The goal would be dramatically improving resolution, resulting in “ground-breaking discoveries about the habitability of nearby planets, dark matter and the expansion of the universe.”

The Entangled Reticulum

There’s something poetic about using a quantum network in order to more clearly see the Reticulum constellation (aka, the net) among other things.

But the poetry runs deeper than that. They say quantum entanglement occurs naturally. Assuming this to be true, I can imagine countless entangled particles streaming off in opposite directions through the universe, encompassing distances that would put the length of a single galaxy to shame.

Large portions of our universe are entangled. The spin of one photon–zinging at lightspeed well beyond the ken of our greatest telescopes–could be entangled with a local photon that happens to meet your retina on a starry night. Thus, the universe is an infinitely complex reticulum of star stuff lighting our consciousness with instantaneous connections from unimaginable distances.

Featured image: Star-forming region called NGC 3324 in the Carina Nebula. Captured in infrared light by NASA’s new James Webb Space Telescope, this image reveals for the first time previously invisible areas of star birth.

The Universe of Seurat and Rovelli

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

Falling for Quantum Gravity

We’ve gone through Chapters 1, 2, 3 and 4 of Reality Is Not What It Seems. The abstract groundwork has been laid, the rhetorical lumber all trucked in, and now it’s time to start building a brand-spanking-new theory of reality on quantum gravity!

Groovy. This particular post is my attempt to distill what I learned in Chapters 5, 6 and 7 of Rovelli’s treatise on quantum gravity.

Teeny Weenie Itsy Bitsy (and then Some)

As physicists started trying to make general relativity and quantum mechanics compatible with one another, they came up with a variety of ideas. One of them–the one Ravelli favors–is the idea of quantum gravity, an idea that hypothesizes that space itself can be be broken down into teeny, tiny basic components.

How tiny? Rovelli says they would be Planck length, which he describes as follows:

To give an idea of the smallness of the scale we are discussing: if we enlarged a walnut shell until it had become as big as the whole observable universe, we would still not see the Planck length.

So, “tiny” doesn’t even begin to cover it. This is almost the definition of infinitesimal, assuming it actually exists outside the confines of the minds of the quantum gravity theorists.

Space Is a Reticulum

Sometimes quantum gravity is called “loop quantum gravity” because some solutions to what’s known as the Wheeler-DeWitt equation–which is seminal to this school of thought–depends on closed lines in space, aka loops.

Remember Faraday lines from “May the Forces Be With You”? Well, the loops are Faraday lines of the gravitational field (as opposed the electronic fields that Faraday was discovering). These lines are not just in space, according to the theory, they are the stuff from which space itself is woven. How cool is that? I makes me think of the Great Norns of Norse mythology, spinning time and space and the fate of humankind.

In a sense, then, space is an enormous reticulum (or “graph”) in which the lines intersect. The intersections are “nodes” and the lines themselves are “links.” Those nodes are the quanta of space. This means, according to the loop theory, that space is not a continuum, as has long been assumed. It’s made up of those fantastically small atoms of space (though space itself is the gravitational field, according to this theory).

More Networks, This Time Spinning

So, if the gravitational field is woven of these quantum particles of space, then how do we talk about specific networks of them? Well, the lines between the nodes are viewed as half-integers, and those integers are called “spin” in the lingo of quantum physics. And so….Rovelli calls these little networks “spin networks.” The networks “represent a quantum state of the gravitational field.”

I don’t know how to properly conceive of spin networks, so for now I’m thinking of them as molecules. That is, atoms make up molecules and nodes make up spin networks. But this isn’t how Rovelli describes them so I’m probably way off.

One of the ways in which my molecule metaphor fails is that molecules actually exist as a thing (I think) whereas spin networks aren’t really entities at all. Rather, they are, like quantum particles, clouds of probabilities “over the whole range of all possible spin networks.”

But they look pretty simple when depicted on the page:

Source: https://en.wikipedia.org/wiki/File:Spin_network.svg

The image above is identified as a spin network but, unlike the version in Rovelli’s book, the lines are not represented by half integers, which I thought represented the quantum spin. Still, you get the idea.

Let’s allow Rovelli sum it up for us:

At extremely small scale, space is a fluctuating swarm of quanta of gravity that act upon one another, and together act upon things, manifesting themselves in these interactions as spin networks interrelated with one another.

This leaves me visualizing thick clouds of mosquitos down in the Everglades, which may not be quite what he intended. But, ready or not, it’s time to deal with time.

Got No Time

According to Rovelli’s ideas, time doesn’t exist apart from the gravitational field. (Side note: Do we really need to keep calling it the gravitational field? Seems kind of lame for something this essential. How about The Lattice of Existence? Maybe The Network of God, or even The One True Reticulum? As I said before, physicists are usually shit as namers and even shittier as marketers, though I’d admit that stealing “quarks” from James Joyce was kind of genius.)

Anyhow, time pops out of this Lattice of Existence (trademark!).

This may seem a bit nuts, but Einstein has already taught us that time is elastic, relative and linked to velocity and gravity. So Rovelli is just doing Weird Al one better. In a sense, time ceases to exist altogether or at least it does at the Planck scale. Time is only the measure of how the loops and nodes interact. It is emergent.

Spinfoaming at the Mouth

We already discussed spin networks. Now let’s graduate to spinfoam, which sounds a lot like the suds one sees in one’s washing machine as it gyrates noisily away. Here’s how Wikipedia defines it: a topological structure that “consists of two-dimensional faces representing a configuration required by functional integration to obtain a Feynman’s path integral description of quantum gravity.”

Does that help you? No, me either.

Let’s start again. The “foam” metaphor comes from the foam that you and I are familiar with. I think the image below is a very cool portrayal of literal foam, maybe helping us better visualize the network-like quality of spinfoam.

Paul VanDerWerf from Brunswick, Maine, USA: https://commons.wikimedia.org/wiki/File:Soap_Bubbles_(41493399275).jpg

And the “spin” part, of course, comes from the quantum mechanical notion of spin, to which we alluded earlier.

Rovelli writes that spinfoam “is made of surfaces that meet on lines, which in turn meet on vertices, resembling foam soap bubbles.” My impression is that spinfoam is a tool that merges two calculation techniques used by quantum physicists: a Feynman diagram and a lattice approximation. Rovelli provides more information about these but I’d clearly need a lot more education to understand them to my satisfaction.

You can see a representation of spinfoam here. Spinfoam is apparently what happens when a spin network moves through time. The lines become planes and the nodes become lines. You know how you can draw a series of stick figures on a small pad of paper and then flip the pages real fast to produce the illusion of moving animation? Well, that’s kind of what spinfoam is: the animation of the spin network moving forwards (or backwards!) in time.

The Universe Dresses Up in Spacetime but Is Secretly …

Rovelli argues that if you sand the universe down to the very bottom layer, you don’t find a beautiful hardwood floor (or spacetime or even oodles of particles). You find — dun dun dun! —covariant quantum fields.

Hah, I bet you’re so surprised, thinking I was going to say “gravitational field”! But, no, now we have a new and equally wonky term that stumbles trippingly off the tongue: covariant quantum fields.

Sigh. More Star Trek jargon to be rattled off by Geordi La Forge on the bridge of the Enterprise.

As I said, physicists are shit at naming stuff.

On the other hand, they sure can weave a tale.

Nice job, Professor.

Featured Image: John Tenniel's illustration from The Nursery "Alice" (1889). See https://commons. wikimedia.org /wiki/File: Alice_drink_me.jpg

Now You See Me, Now You Don’t

Out of the Frying Pan

So far, we’ve covered ancient atoms, electromagnetism and the theory of relativity. In Chapter Four of Reality Is Not What It Seems: The Journey to Quantum Gravity, we finally enter the last and strangest realm of known physics: quantum mechanics (aka, quantum physics).

In my last post, I compared trying to some to terms with the implications of Einstein’s model of reality to taking the red pill in The Matrix, leaving behind our comfortable (though false) notions of stable time and space in order to live in the bizarre, uncomfortable and yet often beautiful and exciting realm of spacetime.

Live free, Neo!

But entering the realm of quantum mechanics is something else. Just as you’re coming to terms with spacetime, you’re told that, by the way, spacetime is also a kind of matrix. An even stranger and more mysterious one. A matrix that isn’t populated by Agents trying to keep the truth from you but rather by gaggles of egghead physicists doing their damnedest to explain it to you….between their extended bouts of arcane squabbling.

Want to go back to your comfy pre-relativity matrix? Too late, Neo.

Into the Fire

So, let’s get down to explaining this new realm. Rovelli specifies that our quantum reality has three primary characteristics: granularity, relationality and indeterminism.

Hey, Why Is My Reality All Pixelated?

Let’s start with granularity. The short version is that, for the sake of convenience, a guy name Max Planck assumed that the energy comes in bite-sized (okay, smaller than that, but finite nonetheless) packets when doing his calculations.

Not long after, Einstein said something like, “Hey, you know what, Max? Energy really is made up of packets. What do you know!” (And, so, yes, the original Weird Al is one of the fathers of quantum mechanics and not just relativity).

Einstein claimed that this granularity extended to light, a form of energy. Most of the other physicists said, “No way! James Clerk Maxwell says light is a wave and waves don’t come in convenient bite-sized packets.”

To which Einstein said something like, “I guess it’s both! Beats the hell out of me how that could be true but let’s just go with it and see where it leads.”

And, wow, those breadcrumbs led to some very strange places…

Wait, They Were Just Here a Second Ago!

Next up is relationality, which is a boring name for something utterly bizarre. Rovelli sums it up in just three short sentences: “Electrons don’t always exist. They exist when they interact. They materialize in place when they collide with something else.”

So, you’re asking, how can that possibly be? Aren’t electrons just a part of an atom, like your arms and legs, nose and mouth are part of you? It’s like saying a person’s left arm doesn’t exist unless they happen to bump into somebody else. How does that work? you ask. I haven’t a clue, but electrons are apparently just ghosts that appear during interactions with one another.

Even though it was his personal bread crumb trail, Albert Einstein thought this was all too strange to be true. But there’s this other physicist, Paul Dirac, who didn’t seem to have problems with it. Rovelli writes, “For him the world is not made of things; it’s constituted of an abstract mathematical structure that shows us how things appear, and they how behave when manifesting themselves.”

Speaking of the problems posed by Dirac, Einstein groused, “To maintain an equilibrium along this vertiginous course, between genius and madness, is a daunting enterprise.”

Rovelli indicates that objects (though what really constitutes an object?) can still have characteristics such as mass while they are not interacting with one another, but the object’s “position and velocity, its angular momentum and its electrical potential only acquire reality when it collides–interacts–with another object.”

Okay, can it get any weirder? Glad you asked!

I’ve Determined that I Can’t Determine

Last up is indeterminacy. Einstein hated this part. He famously said, “God does not play dice with the universe.”

What he objected to was the fundamental quantum physics idea that one cannot predict what any given particle is going to do. Rovelli wraps it up like this: “While Newton’s physics allows for the prediction of the future with exactitude, if we have sufficient information about the initial data and if we can make the calculations, quantum mechanics allows us to calculate only the probability of an event. This absence of determinism at a small scale is intrinsic to nature.”

“Intrinsic to nature” — let that one sink in. All you can do is give and get probabilities. It’s all a big dice game, as far anyone can tell.

Or maybe it’s a baseball pitcher with lousy ball control. For some reason, I think of the movie Bull Durham in which the rookie pitcher Nuke can throw hard but doesn’t know where any given pitch is going to go. “Hell if I know where the damn thing’s going…” Nuke’s catcher, Crash, tells a nervous batter. (And, yes, Bull Durham fans, I know it’s a ploy on Crash’s part but, hey, it’s just a metaphor).

Anyway, what Dirac’s equations can do is give you a range of the possibilities and then a calculation of the probabilities within that range (At least, I think that’s right, based on what I can determine. Get it? Determine. Indeterminacy? Ok, never mind).

We Cobbled Her Together But She Sure Does Run Good

Over the years, physicists “cobbled together” (Rovelli’s phrase) what we now call the Standard Model (physicists are crap at naming and marketing, it appears). He sums up:

The Standard Model is completed by the 1970s. There are approximately fifteen fields, whose quanta are the elementary particles (electrons, quarks, muons, neutrinos, Higgs, and little else), plus a few fields similar to the electromagnetic one, which describe electronmagnetic forces and the other forces operating at a nuclear scale, whose quanta are similar to the photons.

The thing is, this junky heap of particles, fields, equations and whatnot turn out to be extremely robust and fast around the corners. Experiments keep confirming it and engineers depend on it to build all our fancy electronic gadgets. In the end, it’s the model that everybody buys.

Now Comes the Hard Part

So, quantum mechanics works like a charm. But so does Einstein’s theory of relativity. The problem is that the two explanations don’t work well together. One works super well in the macro world and one works super well in the micro world, but nobody knows how to marry the two.

So, that’s where Rovelli and others come in. They want to settle these irreconcilable differences by building a house that both theories can comfortably fit in. Heck, they want more than that. They want our two theories spooning each other, finishing one another sentences, lovingly telling us stories of how their many zany antics and impassioned conflicts finally ended in a Harry-and-Sally-type romance that we can all laugh about now.

So, will they or won’t they? Stay tuned. Next week: Falling For Quantum Gravity

Feature image: Clara Ewald's portrait of Paul Dirac: From https://commons.wikimedia.org/wiki/File:Clara_Ewald_-_Paul_Dirac.jpg

How Grainy Is Your Reality?

I’m in the process of reading the book Reality Is Not What It Seems: The Journey to Quantum Gravity by Carlo Rovelli. I figured I’d write a bit about each chapter as I go along. Maybe this will help me integrate the ideas a better than if I simply read it.

I’ll give it a try, anyway, even if am suffering from the horrors of the WordPress editor at the moment (BTW, what gives, WP? Why did you move from a relatively user-friendly UI to this exceptionally unfriendly block system that specializes in producing heartburn and headache in equal proportions? Just wondering.)

The Ancient Power of Democritus

The first chapter is called “Grains,” which I assume is a reference to two things: 1) the fact that we are starting with the seminal ideas of today’s physics going back to ancient Greece and 2) the fact that the topic is atoms, which are the grainy little building blocks that reportedly make up our reality.

Rovelli, a theoretical physicist and science writer, insists that our current best understanding of reality began around 450 BCE with a Greek named Leucippus, the teacher of Democritus. “Together,” writes Rovelli, “these two thinkers have built the majestic cathedral of ancient atomism. Leucippus was the teacher. Democritus, the great pupil who wrote dozens of works on every field of knowledge, was deeply venerated in antiquity, which was familiar with these works.”

Rescued from Obscurity by Latin Poetry?

Why don’t we know more about these two great philosophers? Because, according to Rovelli, the texts of these philosophers were systematically destroyed by Christians in accordance with their ideas about reality. “Plato and Aristotle, pagans who believed in the immortality of the soul or in the existence of a Prime Mover could be tolerated by a triumphant Christianity,” he writes. “Not Democritus.”

These losses are tragic, especially given the very long list of works by Democritus, who looks to have been just as prolific as Aristotle. The good news is that a little about the philosophy of atomism was preserved in a work by the Latin poet Lucretius: that is, De rerum natura, or The Nature of All Things.

The Catholic Church really had it out for atomism. In the 1500s, they even tried to ban the works Lucretius but failed. Lucretius was already in the bloodstream of European thinkers and they were not going to give him up. Rovelli describes the work as “an articulate and complex structure of thinking about reality, a new mode of thinking, radically different from what had been for centuries the mind-set of the Middle Ages.”

Einstein and Atomism

So atomism survived by the skin of its philosophical teeth. Would we have today’s understanding of the universe without it? Impossible to know, of course, but Rovelli seems to think not. What’s especially interesting is Einstein’s role in atomism, a role I’d never heard about before. Apparently Einstein knew of the experiments of the 19th century biology Robert Brown, who graphed the movement of small particles suspended in water. The particles, it turns out, do not fall straight down. They move around in a zigzag manner.

Why does this happen? Because, Einstein hypothesized, the molecules in the water are colliding with one another. He even figures out the the approximate size of these tiny particles: “From observations of granules drifting in fluids, from the measurement of how much these ‘drift’ — that is, move away from position — he calculates the dimensions of Democritus’s atoms, the elemental grans of which matter is made. He provides, after twenty-three hundred years, the proof of the accuracy of Democritus’s insight: matter is granular.”

A Suspiciously Specific Dawn

Do I buy all this? Sort of. My impression is that it’s seriously oversimplified, as good stories often are. But it sounds generally true. Yes, I’m skeptical that the “first dawn of scientific thought” occurred only at Miletus in the sixth century BCE. That seems overly specific to me. I imagine that scientific thought is more organic than that, having begun thousands of years before when prehistoric humans slowly uncovered the workings of the natural world.

I think about Ötzi the Iceman, for example, who lived about 5,000 years ago and how his hair was heavily contaminated with copper and arsenic, suggesting he was somehow associated with copper smelting. That is pretty serious technology for an age millennia before Democritus was born. After all, such technology requires considerable patience, insight and multi-generational knowledge. In short, I doubt metallurgy is possible without the kind of reasoning that may itself be considered part of an extended dawn of scientific thought.

But that’s just nitpicking. Even if he is simplifying and mythologizing a bit, Rovelli tells a good and insightful story, one that I’ll remember even if I ultimately get a little fuzzy about the dates and names.

Featured image:  "The Young Rembrandt as Democritus the Laughing Philosopher", a portrait study, half length oil on copper, bears monogram top left "HL?" and lengthy French hand written inscription verso, 23.75 × 17 cm’). Go to https://commons.wikimedia.org/wiki/File:Rembrandt_laughing_1628.jpg