Ways Physics and Cosmologists Can Baffle You

Cosmos

Night

I dreamed that I was looking at the universe, the milky way perhaps, on a screen as large as the side of a building. In the picture the stars are in motion, moving in a way that seems remarkably predictable for an expanding cosmic landscape. There is a character standing to the left of the big screen, waiting for me. He has gray hair and looks a little bit like Colonel Sanders, but he is actually the teacher. And he is patient. He is waiting for me to ask him about the scene, but I have been avoiding it.

Day

I have been trying to understand the basic principles of physics for a few years now, mainly because of my interest in quantum computing. But no matter how many books I read on the subject, I am still baffled by most of it. Sometimes my questions seem too big to ask, and yet my interest continues. Thankfully there are a few encouraging teachers, like Leonard Susskind, director of the Stanford Institute for Theoretical Physics, who say it’s perfectly reasonable to feel challenged here.

From Leonard Susskind to Everyone:

“A number of years ago I became aware of the large number of physics enthusiasts out there who have no venue to learn modern physics and cosmology. Fat advanced textbooks are not suitable to people who have no teacher to ask questions of, and the popular literature does not go deeply enough to satisfy these curious people. So I started a series of courses on modern physics at Stanford University, where I am a professor of physics. The courses are specifically aimed at people who know, or once knew, a bit of algebra and calculus, but are more or less beginners.”

The response was overwhelming and it was suggested that Stanford put them up on the internet. You can find them at: http://www.learnoutloud.com/Catalog/Science/Physics/Modern-Theoretical-Physics/23022

Susskind On Why Physics Is So Hard

Susskind says that with physics, you have to go through the initiation rights of learning mathematics, which is why physics is so hard for the general public.

“Look, the process of modern physics has been very much the process of physicists rewiring their brains with abstract mathematics. Nobody, including me or anybody else, can visualize and see four dimensions in their head. But it’s very easy to add to x, y, and z, another letter of the alphabet and simply do with the four letters what you used to do with the three letters.

So you make an abstract mathematical visualization that you can’t see in your head, but through the process of rewiring you learn new ways to think about things. Well, I can’t use that when I talk to people who are not mathematically trained, so you use analogies, metaphors. So it is effective, but always at some level it is wrong. It doesn’t capture everything correctly.”

For more, watch The Cosmic Landscape: Leonard Susskind at the Commonwealth Club of California.

Susskind

— DJ

Night and Day is an online journal that contrasts my dreams with my daytime activities. I refer to these posts as episodes because I only recall my dreams sporadically, and because they are at best loosely connected to my days.

What We Call the Past Is Built On Bits

BinarySmIt’s impossible to talk about information theory without talking about Claude Shannon. In 1948, the same year that Bell Labs introduced the transistor, Shannon published a monograph in The Bell System Technical Journal titled, A Mathematical Theory of Communication. In it, the 32-year-old who was then part of the Bell Labs mathematical research group coined the word bit, declaring it a unit for measuring information.

Information theory began as a bridge from mathematics to electrical engineering, and from there to computing. It’s a transformation that is chronicled by James Gleick in The Information: A History, A Theory, A Flood. This ambitious book traces the history of communications through the centuries to teach us about the language of drum beats, the decline of oral histories and the persistence of the word, alphabets, patterns, the printing press, electricity, Morse code and telegraphs, telephone switchboards, wires, networks, computers, algorithms, and modern day, social-sharing apps.

We learn that logic descended from the written word, that mathematics followed the invention of writing, and that information is physical. We learn that the first English dictionary was made by Robert Cawdrey, a village schoolmaster and priest, in 1604. That the first Oxford English Dictionary was published in 1933. And that the book of tables by Regiomontanus that Christopher Columbus carried as an aide to navigation was printed in Nuremberg two decades after the invention of moveable type in Europe.

We meet Charles Babbage, Ada Byron, Norbert Wiener, Richard Feynman, Albert Einstein, Stephen Hawking, Claude Shannon, Alan Turning, John von Neumann, and Edgar Allen Poe, the American writer who helped popularize cryptography. As Gleick crisscrosses the disciplines of mathematics, physics and computing we begin to appreciate just how strong the bonds of science and technology really are. And that is probably the point.

One of my favorite stories comes from 1943. Claude Shannon routinely met Alan Turing at teatime in the Bell Labs cafeteria, but they couldn’t discuss their work because it was a secret. It was the height of World War II and they were both cryptanalysts. Instead, Turing showed Shannon a paper he had written seven years earlier, “On Computable Numbers,” about the powers and limitations of computing machines. They talked about the possibility of machines learning to think at a time before transistors and electronic computers even existed. It wasn’t exactly a chance encounter and it gave rise to Turing’s now famous question, “Can machines think?

Turing’s machine never really existed. It was a thought experiment in the early days of information theory and the vision that Shannon and Turing shared actually had more to do with logic than electronics. Gleick explains that what Alan Turing and Claude Shannon had in common was codes.

“Turing encoded instructions as numbers. He encoded decimal numbers as zeroes and ones. Shannon made codes for genes and chromosomes and relays and switches. Both men applied their ingenuity to mapping one set of objects onto another: logical operators and electric circuits; algebraic functions and machine instructions. The play of symbols and the idea of mapping, in the sense of finding rigorous correspondence between two sets, had a prominent place in their mental arsenals.”

These conversations helped Shannon fuel his theory of information and the idea that once information became digital, it could be transmitted without error. It became a unifying theory for all sorts of communications and quickly distinguished him as the father of information theory.

Gleick also tackles the complex subject of quantum computing, which deals in quantum bits, or qubits rather than bits. With roots in quantum physics it’s easy to get lost in this area, but he does a pretty good job of making the concepts understandable for the layman. And he offers some insights into why this kind of computing matters.

“Whereas an object in classical physics, typically composed of billions of particles, can be intercepted, monitored, observed, and passed along, a quantum object cannot. Nor can it be copied or cloned.” And this is precisely why quantum computers—in theory—can solve certain classes of problems that were previously considered infeasible, he says. Cryptography is one common answer to “why quantum computers?” But artificial intelligence is often cited as well.

This book covers a lot of ground. But the common thread throughout is that information is the vital principle. Gleick says it pervades the sciences from top to bottom, transforming every branch of knowledge.

In 1990, the American physicist John Archibald Wheeler suggested that information is fundamental to the physics of the universe, “It from Bit,” he said. “Every particle, every field of force, even the space-time continuum itself, derives its function, its meaning, its very existence entirely from answers to yes-or-no questions, binary choices, bits.”

Shannon introduced us to the science of information theory. Wheeler taught that what we call the past is based on bits. And Gleick connects the dots.

— DJ

The Meaning of Inflation

When we hear about inflation, we naturally assume it means that prices are going up. Because that’s what economists have taught us to think. But talk to a physicist, and you will soon learn that inflation has an entirely different meaning.

Inflation, for physicists, is an extension of the Big Bang theory. And the reason it is important is that it helps answer some of the difficult questions the theory raises, like how is it possible that the Universe has an even temperature?

If you’re like me, you probably learned about the Big Bang theory in school. And if you asked me what it meant just a few weeks ago, I would have confidently told you that it is the scientific explanation for how the Universe began.

But if you asked me today, I would start by telling you that the Big Bang theory is still a theory. And as Stephen Hawking puts it, a theory is just a model of the universe.

“Any physical theory is only provisional, in the sense that it is only a hypothesis: you can never prove it.” – Stephen Hawking

So when astronomers at the South Pole discovered faint spiral patterns from the polarization of microwave radiation left over from the Big Bang, it generated a lot of excitement in the scientific community.

In Ripples From the Big Bang, Dennis Overbye explains how the team, led by John M. Kovac of the Harvard-Smithsonian Center for Astrophysics, found evidence to support the theory of inflation, which explains how the universe expanded so uniformly and so quickly in the instant after the Big Bang 13.8 billion years ago.

Overbye says that if the chain of evidence and reasoning holds up, it could lend support to the fervently hoped-for unification theory of Einstein’s gravity, which shapes the universe, and quantum theory, which governs the behavior of atoms inside it. And, he says, the discovery suggests that gravity, too, might ultimately be described by the same weird quantum rules as those that describe the other forces.

Photo credit: NASA

Photo credit: NASA

Don’t miss the graphic in this article that really helps explain it all.

[UPDATE: In a remarkable coincidence (spooky entanglement?) I just read an article in LiveScience that said three physicists were awarded the prestigious Kavli Prize in Astrophysics today (May 29) for their work on cosmic inflation. Congratulations to Alan Guth of MIT, Andrei Linde of Stanford University, and Alexei Starobinsky of the Landau Institute for Theoretical Physics in Russia.]

–DJ

Night and Day — Episode 5

Night

“What if it’s all just a hologram?” I ask.

“That’s ridiculous,” she says as she walks away from me.

Day

The controversial notion that our experience of reality is nothing more than a hologram pierced my brain when Brian Greene suggested it in the NOVA series, The Fabric of the Cosmos, back in 2012. And I guess the idea stuck with me because it just popped up in a dream I had.

Brian Greene is a professor of physics and mathematics at Columbia University in New York City, and when he explains physics on a TV show like NOVA I take it seriously. So I started doing some research to get the backstory on holograms.

In an interview by WIRED magazine, Greene explained that the idea that reality may be akin to a hologram is based on a wonderfully weird collection of ideas and theoretical studies developed over the last 30 years that go under the heading of the “holographic principle.”

What started as an attempt to understand the quantum properties of black holes soon turned into a scientific debate over the fundamental laws of physics as scientists wondered; “what happens to the information that an object contains when it falls into a black hole”?

And this led physicists to come up with the idea that when an object falls into a black hole, a copy of all of its information content gets “smeared out” on the surface or the horizon of the black hole. Flattened out in a sense—like a series of 0′s and 1′s, the way information is stored in a typical computer. And that idea, he said, would suggest that a three-dimensional object inside the black hole could be described by information on a two-dimensional surface that surrounds the black hole.

According to Greene, the reason this is interesting is because the space inside a black hole is governed by the same laws as space outside a black hole, or space anywhere for that matter. The point being, if a 3-D object inside a black hole can be described by 2-D information on a surface that surrounds it, then that lesson could be generalized to include you and me and everything else we consider reality.

“Now, this starts to sound like a hologram,” said Greene. “A hologram is a thin 2-D piece of plastic which, when illuminated correctly, yields a realistic three-dimensional image. The idea is we may be that three-dimensional image of this more fundamental information on the 2-D surface that surrounds us.”

In a related article, Our Universe May Be a Giant Hologram, Greene used an analogy to help explain: “If this line of reasoning is correct, then there are physical processes taking place on some distant surface that, much as a puppeteer pulls strings, are fully linked to the processes taking place in my fingers, arms, and brain as I type these words at my desk. Our experiences here, and that distant reality there, would form the most interlocked of parallel worlds. Phenomena in the two—I’ll call them Holographic Parallel Universes—would be so fully joined that their respective evolutions would be as connected as me and my shadow.”

Greene admits that the holographic principle and some of the ideas explored in The Fabric of the Cosmos represent some of the strangest features of modern science, but he also claims they are well-grounded in mathematical research and observational data.

“Now, let me just point out, this is a hard idea even for physicists who work on it every day to fully grasp,” said Greene. “We’re still trying to really dot the i’s and cross the t’s and understand in detail what this would mean. But there are many who now take this idea very seriously, that we may be a kind of holographic projection.”

I think it’s even harder for the general public to grasp. And if it’s true, I can’t help but wonder, who, or what is behind the projector?

— DJ

Night and Day is an online journal that contrasts my dreams with my daytime activities. I refer to these posts as episodes because I only recall my dreams sporadically, and because they are at best loosely connected to my days.