Tag: theory of relativity

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

Einstein and the Big Squid

Taking the Red Pill of Relativity

Now things get weird. In the first post about Rovelli’s Reality Is Not What It Seems, we focused on atoms. Despite the strange fact that medieval Christians tried to censor the concept of atoms, they do not score very high on my weird-shit-o-meter. I was brought up with them, so they seem as friendly as eating potato chips on a comfortable couch.

In the second post, we got into electromagnetism. But, considering that most of us live enmeshed in cocoons of wire and wifi, it’s hard to see that topic as outlandish, however much our forebears would have been astonished.

But in Rovelli’s third chapter, the topic of this post, we’re forced to choke down a red pill if we want to enter the spacetime reality of Albert Einstein’s mind, thereby exiting The Matrix of our comfortable everyday reality where time and velocity seem as easy to grasp as a digital readout.

You’d think that by now we’d be accustomed to the original Weird Al’s big brain. I mean, we’ve had a century or so to get acclimated to this stuff. But, speaking for myself, I’m still struggling to cope with the idea that the world is not what it seems.

Present But Not Accounted For

Rovelli tries. But, despite the cartoons, his section on the “extended present” is hard to swallow. How and why has the present moment been extended by the Special Theory of Relativity?

I assume it has to do with the speed of light and relative time, but you’ll need to take it on faith within the context of this chapter. Here’s an example:

[O]n the moon, the duration of the extended present is a few seconds, and on Mars a quarter of an hour. This means we can say that on Mars there are events that are yet to happen, but also a quarter-of-an-hour of events during which things occur that are neither in our past nor in our future.

I find this hard to wrap my brain around and wish Rovelli had gone to greater lengths of explain the details. I remember getting a deeper glimpse of time relativity when pondering the ideas in the book Why Does E=mc2 (And Why Should We Care?), but I’ve since lost it (the glimpse, not the book). And now I’m wondering if I’ll need to bear down on that text again in order to grasp Rovelli’s arguments. We’ll see.

Space Is a Monster Mollusk

Okay, let’s put the “extended present” into a box (perhaps along with Schrodinger’s cat) and come back later to see what happened. For now, I want to focus on another statement in Chapter Three:

What if Newton’s space was nothing more than the gravitational field? This extremely simple, beautiful, brilliant idea is the theory of general relativity…. Newton’s space is the gravitational field. Or vice versa, which amounts to saying the same thing: the gravitational field is space….We are not contained within an invisible, rigid scaffolding: we are immersed in a gigantic, flexible mollusk (the metaphor is Einstein’s).

Okay, despite the Cthulhu vibe, I understand this better than the concept of extended present. I get the whole spacetime-curved-by-big-hunks-of-matter idea. I get that everything’s moving and has speeds only relative to everything else and everything is in constant flux. I even kind of (though not really) get the idea that time flows faster at the top of a mountain rather than in a valley.

But spacetime is the same thing as the gravitational field? Was that originally part of the Theory of Relativity? Apparently I’m not the only one confused. I wonder if that’s part of scientific history or just a tenet of the quantum gravity hypothesis, which is the ultimate subject of the book.

A Universe Designed by Escher

The latter sections of Chapter Three are mostly focused on how the universe may be a humongous globe with an extra dimension stuck in there. Einstein conceived a way in which the universe might be finite while still having no discernable boundary. Rovelli uses the metaphor of a globe:

On the surface of the Earth, if I were to keep walking in a straight line, I would not advance ad infinitum: I would eventually get back to the point from which I started. Our universe could be made in the same way. I fly around the universe and eventually end up back on Earth. A three-dimensional space of this kind, finite but without boundary, is called a “3-sphere.”

Although he goes on for another 12 pages or so, for me the above is the essence of the discussion. And, I kind of get it, or at least think I do, because we all understand the metaphor of the globe. Whether I can can truly conceive the shape of the universe like this, however, is another matter. It’s something to work on.

It’s Networks All the Way Down

Boiling it all down, I take away two main insights from this chapter. First is the idea that space as we (or at least I) sometimes think of it doesn’t exist. There are no vast empty spaces in space. It is jam-packed with gravitational and electromagnetic fields light waves, radio waves, gamma rays, microwaves, etc. In fact, maybe space is nothing more nor less than an unthinkably immense gravitational field.

Whatever space is, however, it’s certainly not mostly empty. It is a packed and fluctuating landscape in its own right. Jupiter is a not a planet but a mountain, one that we can climb and look down at the curved and rippling real estate of our solar system, if we’re willing to see beyond the merely visible.

My second insight is that network describes the scene even better than landscape. In my mind’s eye, I see block-and-tackle pulleys everywhere, connecting everything in our solar system (and the greater universe, of course) in a constantly shifting network.

Some mythologies have it that the Earth is supported on the back of a giant World Turtle. But what does the turtle stand on? There’s the old joke that, well, it’s “turtles all the way down” in a kind of infinite regress.

Perhaps it’s less of a joke to say that the universe is a network of networks. What do the networks attach to? Well, other networks via gravitational forces. I guess we could say it’s networks all the way down.

Featured image: Artist's concept of the Interplanetary Transport Network. The green ribbon represents one possible path from among the infinite number possible within the larger bounding tube. Constricted areas represent locations of Lagrange points. Wikimedia Commons

May the Forces Be with You


Making Up with Plato and Aristotle

In the second chapter of Reality Is Not What It Seems, Rovelli takes us on another millennia-spanning tour of physics. He starts by making up with Plato and Aristotle, whom he had previously seemed to denigrate by comparison with the great and yet savagely censored Democritus (see previous post). Then he takes us on a whirlwind tour of the ideas of Galileo, Newton, Faraday and Maxwell.

Rovelli says that Aristotle, who invented the name of the physics discipline, deserves credit for describing the physical nature of the universe in a systematic if unquantified manner. He may not have understood the universe well by our standards, but what he wrote was coherent, rationale and served at as humanity’s best description of the physical universe for many centuries.

As for Plato, he championed mathematics (and, in particular, geometry) as a way of understanding the universe. Without mathematics, of course, we could not possibly have modern physics.

The Great Experimenter

Nonetheless, it took a long time before what we call experimental science emerged, according to Rovelli, who boldly states that “experimental science begins with Galileo” (aka, Galileo di Vincenzo Bonaiuti de’ Galilei, born February 15, 1564 and died January 8, 1642).

Once again, Rovelli seems to be simplifying in order to tell a clear, compelling and succinct story. I’m all in favor of that, but in reality there were probably a lot of experimenters before Galileo, even if they were not as systematic, brilliant and productive. For example, the Greek physicians Herophilos (335–280 BCE) and Erasistratus of Chios used experiments to further their medical research. Erasistratus repeatedly weighed a caged bird to determine its weight loss between feeding times.

But let’s go with Galileo as the first truly great experimenter. In a very small nutshell, he discovered that objects do not always fall at a constant speed and that, indeed, they pick up speed as they go: about 9.8 meters per second per second. This number comes up a little latter in history, speeding (so to speak) modern physics on its humanity-changing path. (By the way, the science fiction novel by Kim Stanley Robinson, Galileo’s Dream, goes into some detail about his experiments, insights and life; if you want to know more about Galileo without reading an actual biography, I’d recommend the book.)

Absurd Realities from Isaac

When Isaac Newton (born December 25, 1642 and died March 20, 1726) famously said, “If I have seen further it is by standing on the shoulders of giants,” he must have been thinking of Galileo as one of them.

Inspired by the moons of Jupiter (discovered by Galileo, of course), Newton conducted a thought experiment (a technique Einstein latter became especially famous for) in which he imagined a little moon orbiting the earth just above our highest mountain tops.

“Now,” writes Rovelli, “an object that orbits does not go straight: it continually changes direction, and a change of direction is an acceleration. The little moon accelerates toward the center of Earth. This acceleration is easy to compute. Newton makes the simple calculation and the result is … 9.8 meters per second per second! The same acceleration as in Galileo’s experiments for falling bodies on Earth.”

So Newton figures that the force that would cause the little moon to orbit around the Earth is the same one that Galileo measured for falling objects. In this way, he linked heavenly bodies with objects on Earth and came up with the modern idea of gravity, the first of the four basic forces so far identified by science.

But just because Newton came up with the idea and the math associated with it doesn’t mean he wasn’t baffled by it. Indeed, he thought the idea of one physical object (such as the Earth) acting on another physical object (such as the moon) via some distance and invisible thread of influence was “inconceivable” (even though he’d conceived it) and “is to me so great an Absurdity, that I believe no Man who has in physical Matters a competent Faculty of thinking, can ever fall into it.”

Except, of course, we all have “fallen” into it (did he recognize his pun?) for hundreds of years since. What’s more, we still don’t truly understand gravity, even if we have learned quite a bit more about it thanks to other great thinkers.

Mike and Jim’s Excellent Intellectual Adventure

Faraday the Astonishing Autodidact

Then, in the 1800s, two other British brainiacs came along and discovered another fundamental physical force that would change humanity, ultimately putting a powerful computer in the pockets of just about every angst-ridden teenager in the so-called developed world.

The two geniuses in question are Michael Faraday and James Clerk Maxwell, who are typically portrayed as the the original odd couple of electromagnetics. Faraday was an up-by-the-bootstraps scientist who grew up poor and not formally educated, yet he somehow sweet-talked his way into a lab assistant job with the Cornish chemist and inventor Humphry Davy. He was never trained in higher mathematics but, according to another of my favorite books on science history (Conquering the Electron: The Geniuses, Visionaries, Egomaniacs, and Scoundrels Who Built Our Electronic Age by Derek Cheung  and Eric Brach), he had a “uncanny intuition and a superhuman ability to visualize abstract objects, concepts and shapes.”

It was Faraday (born September 22, 1791 and died August 25, 1867) who basically created the first electrical motor, discovering that electrical energy could be directly converted into the kind of energy (that is, kinetic) that makes stuff move. (So, in theory, if there’d been no Faraday, we’d still be driving steam engines around and who knows what Elon Musk would be doing these days).

But, he was more than just a fantastic tinkerer. He came to the conclusion, in Rovelli’s words, that “there exists an entity diffused throughout space that is modified by electric and magnetic bodies and that, in turn, acts upon (pushes and pulls) the bodies. He calls these ‘lines of force.'” So, in essence, Faraday discovered fields!

Faraday created a number of iron filing diagrams in 1851 to demonstrate magnetic lines of force. Source: Royal Institution

Maxwell the Scottish Aristocrat

I love the little I know about James Clerk Maxwell (born June 13, 1831 and died November 5, 1879) because he seems almost god-like in his ability to crystalize the baffling universe into just a few, elegant equations. He was the Einstein of his day. In fact, without him, Einstein may never have crafted his theories of relativity at all. After all, Einstein’s special theory of relativity is often seen as owing its origin principally to Maxwell’s theory of electromagnetic fields.

Here’s what Maxwell achieved. After working 11 laborious years, he was able to embody all the electrical and magnetic principles into just four seemingly simple equations” (okay, there were 20 at first but they were later distilled by yet another Brit, Oliver Heaviside, whose name seems to pop directly out of a Dicken’s novel).

Rovelli says of the equations: “They describe an amazing number and range of phenomena. Almost everything we witness taking place, with the exception of gravity and little else, is well described in Maxwell equations.”

Perhaps most amazingly, Maxwell’s equations suggested that there would be other types of hitherto undiscovered waves aside from those teased out of nature by Faraday. In fact, it wasn’t too long after Maxwell’s death that radio waves were discovered, harnessed and transmitted. Here’s how Wikipedia reports it:

Radio waves were first predicted by mathematical work done in 1867 by Scottish mathematical physicist James Clerk Maxwell. His mathematical theory, now called Maxwell’s equations, predicted that a coupled electric and magnetic field could travel through space as an “electromagnetic wave”. Maxwell proposed that light consisted of electromagnetic waves of very short wavelength. In 1887, German physicist Heinrich Hertz demonstrated the reality of Maxwell’s electromagnetic waves by experimentally generating radio waves in his laboratory, showing that they exhibited the same wave properties as light: standing waves, refraction, diffraction, and polarization. Italian inventor Guglielmo Marconi developed the first practical radio transmitters and receivers around 1894–1895. He received the 1909 Nobel Prize in physics for his radio work. Radio communication began to be used commercially around 1900.

Maxwell never got to see all this because he died of stomach cancer at only the age of 48. If he had lived to be as old as Galileo, he would have seen Hertz generate radio waves, Marconi develop the first practical radio transmitters and receivers, and Einstein publish his special theory of relativity.

I so wish that the young Einstein could have met the old Maxwell, just as the young Maxwell met, interviewed and learned from the old Faraday. Yet life isn’t always fair like that, even for the truly great ones.

Feel the Forces, Luke

At this point in our scientific story, Galileo and Newton have discovered and quantified gravity while Faraday and Maxwell have done the same for electromagnetism. (That last sentence is an oversimplication, but let’s go with it.) Regardless of the names, humanity has learned to better understand and increasingly harness these two forces, not to mention the strong and weak forces discovered later. The forces were already there, of course, but understanding how to manipulate them has brought power that would have been viewed as god-like to people in the past.

In this sense, we are all like Luke Skywalker in the Star Wars universe, except the Forces are genuine. With them have come wonders, of course, but also more dangers. As fun as they might be, I don’t think our cinematic space operas can hold a candle to the narrative in which Forces-wielding humanity finds itself.

The Rise of New Networks

 A network is a group or system of interconnected people or things. Without networks of thinkers who communicate ideas over time, often via the written word, we would have have no real understanding of electromagnetism or the technologies based on that understanding.

These networks of ideas led to the rise of technologically mediated networks, which led to scientific ideas being spread across the world at the speed of light. This is where we are today, our radio waves not only spanning the globe but expanding well beyond it, perhaps one day washing up on alien shores light years away, maybe even reaching the stars of the Reticulum constellation itself.

The Reticulum Constellation. Author: IAU and Sky & Telescope magazine (Roger Sinnott & Rick Fienberg)
Featured image is VFPt dipoles electric from author Geek3. For more information, go to https://en.wikipedia.org/wiki/File:VFPt_dipoles_electric.svg