Friday, December 9, 2016

The Marvelous Museum of Science and Industry

When I was 7 years old, my parents took my brother and me up to Chicago for a short visit -- it's one of my most vivid childhood memories. We visited all of the Chicago museums, but the one that made the deepest impression on me was the Museum of Science and Industry. I can't honestly claim that this was the single experience that set me on my path to a career in science, but it was certainly a major influence. We don't always appreciate the huge impact that apparently trivial experiences have on young children.

What was exhibited at the museum back in 1966? We walked through the German WWII submarine, but I didn't particularly like it. My favorite was a nuclear physics exhibit sponsored by the Atomic Energy Commission. It included a large push-button map that allowed you to "prospect" for uranium, a mock-up of a "hot cell" manipulator for handling radioactive materials, and screen with a dial for producing images of atoms with various numbers of electrons. (The last of these must have made a deep impression -- I later authored a textbook on quantum mechanics). A dive through Google determined that this exhibit was called "Atomsville, USA," and it was presented first at the 1964 New York World's Fair, and then made a brief stop in Chicago for a few months in 1966. Remarkably, you can see a video of it (in its World's Fair incarnation) here.

And what else was at the museum 50 years ago? I vividly remember the "World of Hardwoods," which included the giant face of Paul Bunyan staring back through a window, and a push-button board under a gigantic light-up globe: you could push each button to see where in the world a particular hardwood tree could be found. The AT&T exhibit had three phone booths, from which you could call someone in another booth or talk to a cartoon character. AT&T also sponsored a video phone linked to the science museum in Philadelphia -- my brother and I were too shy to use it.  (It took 50 years for this technology to become a computer-aided everyday reality). There was the famous walk-through heart, and a bizarre theater with mechanical parts of a cell (or were they molecules?) sliding in and lighting up. An internet search revealed that this exhibit was called "Chemical Man."

What has become of these old exhibits?

Monday, December 5, 2016

Worst. Airline. Ever.

I've been flying for 40 years, and after all this time I've finally discovered the worst airline out there. What's more, I'm confident that most of you will agree with me.

I probably should have suspected a problem when I saw the new signage over the entrance at Midway Airport: "Abandon All Hope, Ye Who Enter Here." I was due to fly out of Chicago on Sunday afternoon. But my flight was cancelled, and I didn't make it back home until 1:00 am. In the end, it turned out to be for the best -- the unexpected layover let me take my daughter to the Museum of Science and Industry, which is one of the world's best science museums. I'll have more to say about the museum in my next post.

So the worst airline ever? That's easy -- it's whichever one you flew on most recently.

Update: My disparaging comment about Midway Airport was, of course, a joke. Midway is not at all like hell. It more closely resembles purgatory -- hordes of people sitting around, with no idea when they are going to get out. Then every so often an angel appears and takes away a large crowd of them into the sky. Definitely purgatory.

Friday, December 2, 2016

A Quantum Limit on How Fast You Can Talk

Is there a fundamental upper limit on how fast we can communicate? If you're like me, that limit is set by your despised cable provider (in my case, Comcast, which avoids being the most disliked company in America only by virtue of being ranked ahead of Time-Warner in most of those surveys).

But recently, Raphael Bousso at the University of California has proposed that quantum mechanics sets an absolute upper limit on how fast information can be transmitted. The limit he proposes in his paper is not all that interesting, but the reason for the limit is rather astonishing.

Monday, November 21, 2016

How will the Universe End? The Big Rip and the Little Rip

Some say the world will end in fire,
Some say in ice.
I say it will end in an infinite-density singularity driven by a scalar field with a negative kinetic term.

Who knew that Robert Frost had such a deep grasp of cosmology?

A couple of weeks ago, New Scientist asked me to comment on a recent paper about the Big Rip. What's that all about?

As the universe expands, all of the ordinary matter becomes less dense. That makes intuitive sense -- if you have a fixed amount of matter in an expanding box, then the amount of mass per unit volume has to go down. But in 1999, Rob Caldwell at Dartmouth made a radical suggestion: suppose that as the universe expanded, the density of the dominant form of energy increased instead of decreasing. This leads to very weird behavior -- the Universe enters a superaccelerated phase, with the expansion factor going to infinity at a finite time, at which point the equations break down at a singularity. It was later pointed out by Caldwell, Marc Kamionkowski, and Nevin Weinberg that as the universe approaches this singularity, it expands so rapidly that all of bound structures in the universe would be torn apart. First galaxies would dissolve, then the solar system would disintegrate, followed by the destruction of the earth, our bodies, and then the atoms in our bodies and the nuclei inside the atoms. And we would be dead by then. Caldwell, Kamionkowski, and Weinberg coined the term "Big Rip" to describe this fate for the universe.

So what was my contribution to this? Nothing, actually. I later worked with Paul Frampton and Kevin Ludwick to come up with the "Little Rip." In what sense is the Little Rip "littler" than the Big Rip?

Friday, November 18, 2016

A Dubious Honor

Today I received my subscriber's copy of the Dec. 2016 issue of Analog, which includes my short story, "Fermi Meets Sagan."  I also received a card in the mail letting me know that as of the next issue, Analog is moving to a bimonthly publication schedule, putting out six issues a year. So I have the dubious distinction of having a story appear in the final monthly issue of Analog. Ever.

Monday, November 14, 2016

Reality Intrudes

Blogging will be light to nonexistent until the beginning of December, as I am working on a grant proposal to the NSF. Given the increasing fraction of time that my colleagues (especially in biomedical research) seem to devote to proposal writing, along with a decreasing success rate, I am beginning to wonder if the research funding system is starting to impede scientific research instead of promoting it. But that's a discussion for another time.

Thursday, November 10, 2016

So You Want to be a Scientist

I often meet with high school students interested in pursuing a career in physics or a related field. A lot of the advice I give them regarding their high-school course work is obvious. Take the most advanced math classes that your school offers. Take the most advanced physics classes. But one bit of advice regarding high school courses is both surprising and often unwelcome to these students.

Monday, November 7, 2016

How to Experience a Parallel Universe

I'll admit it -- I'm a sucker for parallel universe stories. The book that really got me hooked on science fiction around 3rd grade was Alan E. Nourse's The Universe Between. I don't think Nourse was a household name in the world of science fiction even back then. He was a medical doctor mostly known for his column in Good Housekeeping. But he wrote a lot of other science fiction that I enjoyed as a kid, including Star Surgeon, which has an astonishing revelation about halfway through the book. Sadly, I suspect his books are all out of print by now.

Among the more recent parallel universe novels, I highly recommend Paul Melko's The Walls of the Universe, based on his Hugo-nominated novella of the same name. And when it comes to parallel universes, the Star Trek episode in which Spock has a beard is sheer genius. That episode was written by Jerome Bixby, who also penned one of the most disturbing science fiction stories ever written. (As I noted in my previous post, Bixby was something of a two-hit wonder, although that's better than being a no-hit wonder).

What I like the best are stories in which the differences between the parallel universes are subtle, not striking. The latter are rather cliched by now. Kennedy assassination averted? Check. Hitler wins World War II? Yawn. And now I'm going to tell you how to experience these subtle differences yourself.

Thursday, November 3, 2016

My Election Prediction

I am going to make my prediction for the upcoming election:  a tie in the Electoral College, throwing the election into the House of Representatives.  How do I know this?  It's based on a very simple fact.

The Three-Body Problem, Final Verdict

In an earlier post I gave my initial reactions to Liu Cixin's novel, The Three-Body Problem, which I had just begun reading. I've finished it now and can give my final opinion. I would give the novel a B+. (Damn professors, always handing out grades...)

Monday, October 31, 2016

Bilbo Dies

William Bowen, who served as president of Princeton when I went there, has died. A very important fact went missing from the published obituaries: all of the students (and who knows how many professors) habitually referred to him as "Bilbo." The card catalog for the main library (yes, there were card catalogs back then) even had the following entry:  Bilbo, see Bowen, William G. I don't know if this entry vanished when the university library catalog went electronic -- it would be a pity if it did.

Wednesday, October 26, 2016

The Day They Nuked Mississippi

Once upon a time, the U.S. government detonated two nuclear bombs in Mississippi.

Was this the sequel to the burning of Atlanta? Did Ulysses S. Grant possess a secret nuclear arsenal? No, these were underground explosions near Hattiesburg back in the 1960s, designed to see how easy it would be to detect nuclear tests using seismic data.

The U.S. engaged in all sorts of wacky nuclear high jinks back in the day. There was Project Plowshare, which explored the possibility of using nuclear bombs for the purposes of earth moving. Just imagine if we had built the Interstate Highway System that way -- you wouldn't need street lights because the highways would glow in the dark.

Monday, October 24, 2016

Chinese Science Fiction - The Three-Body Problem

Traduttore traditore. That was a favorite saying of one of my college Russian professors. It means "the translator is a traitor." Or at least I think that's what it means. I don't speak Italian.

I almost never read science fiction in translation from another language. And the main reason is that most science fiction is written in English. If you can read English, as many readers of this blog can, then you automatically have access to 90+% of the world's published science fiction. There are a few exceptions -- there has long been a thriving parallel world of Russian science fiction -- but most science fiction remains stubbornly Anglophone.

Monday, October 17, 2016

Pokemon? Or Prescription Drug?

My nephew, a fourth-year medical student, is visiting for a month to do an externship at Vanderbilt. He told me about a game that the medical students play: one person announces a name, and the other person has to guess whether it's the name of a Pokemon or a prescription drug.

Here's a sample for you to try.  See if you can figure out which of these are Pokemon, and which are the names of drugs:

A. Remelteon
B. Remoraid
C. Empoleon
D. Zingo

Answer after the break...

Monday, October 10, 2016

In Memoriam: Debbie Jin

I was saddened to learn of the death of Debbie Jin several weeks ago -- she was only 47 years old. Debbie worked at NIST (what used to be called the Bureau of Standards) in Boulder, Colorado. I first met her in my previous incarnation as an Ohio State professor, when we tried to hire her into a faculty position there. Over the years, I've tried to keep track of all of the young superstars who turned down our job offers -- Debbie became by far the most outstanding of all of the "ones who got away."

Debbie worked on ultra-cold systems of atoms. These are the famous "Bose-Einstein condensates" -- bosons are particles that like to clump together, and when you make them cold enough, they all pile into the same quantum state. Fermions, on the other hand, hate each other and don't like to be together. Debbie was the first to produce a "fermionic condensate" in the laboratory. Had she lived, I think she would have been a strong contender for the Nobel Prize. I invited Debbie to give our 2011-12 Slack Lecture here at Vanderbilt, and she gave a spectacular talk. She was also one of the nicest people I've met in the world of physics.

Tuesday, October 4, 2016

The Man Who Knew Infinity: Why are Senior Mathematicians so Calm?

Time for some amateur psychoanalysis. I recently saw The Man Who Knew Infinity, which tells the amazing story of the Indian mathematician Ramanujan and his relationship with the English mathematician Hardy. It's an excellent film, but I won't spoil it for you -- let's just say that if it were fiction instead of a true story, nobody would believe it. The movie does an amazing job of portraying the actual process of doing mathematics. (I wrote earlier about the difficulties of writing math-based science fiction in this post.)

I should admit at this point that I thought seriously about going into mathematics in college.  But I was a good enough mathematician to realize that I was not a good enough mathematician to do mathematics professionally. So I went into theoretical physics instead. I've never regretted my decision, but I do envy the more senior members of the mathematics community for their relative calm, as compared to those of us in theoretical physics. What do I mean by that? You'd think that senior tenured physicists would eventually kick back and relax, instead of continuing to seek awards and other kinds of validation for their work. But it ain't so (and I am as guilty as anyone else). On the other hand, I've found senior mathematicians to be relatively more relaxed about such things. And I have a theory as to why this is the case.

Monday, October 3, 2016

Marvel Superhero Day at School

My daughter's school is sponsoring "Marvel Monday," when everyone is supposed to dress up as a Marvel superhero. What to do? I suggested that she go as the Fantastic Four's Sue Richards, who can turn invisible. Then just skip school that day.

Tuesday, September 20, 2016

Talk at the University of Illinois

I'm giving a talk at the University of Illinois, Urbana-Champaign, this coming Friday at noon on the topic of Science and Science Fiction, followed, at 3:00, by a scintillating colloquium in the Astronomy Department on parametrizing dark energy.

Sunday, September 18, 2016

Announcing the Society of Catholic Scientists

I am happy to announce the formation of the Society of Catholic Scientists. You can tell it's official because we have a website:
The website is still skeletal at this point -- we'll be making additions over the coming month. But you can check out the Board of Directors -- there are some high-powered scientists involved. (I am not one of them. Nor am I a low-powered scientist. I am medium-powered).

Our first major event will be a conference in Chicago in April. The conference dates are on the website, but more details will be posted as they become available.

Friday, September 16, 2016

Enrico Fermi Reimagined as a Marshmallow Bunny

Speaking of Enrico Fermi (as I did in my previous post) brings to mind a competition that the University of Chicago sponsored seven years ago. The competition, open only to U. of Chicago alumni, was to recreate a scene from the campus using Peeps, those marshmallow bunnies and chicks that appear mysteriously every year around Easter and then just as mysteriously disappear. (No one actually eats them, do they?)

I leaped to the challenge, but immediately faced two obstacles. The first was that as a  Ph.D. alumnus of the university, I had spent all of my time at Chicago chained to my desk, with my advisor sliding food under my office door at irregular intervals. So I had no memory of any famous campus scenes to recreate. But one scene did come to mind -- this iconic photo of Enrico Fermi:

There's actually a mistake in this photo -- can you find it?  Answer at the end of the post.
Every physics department has its heroic figures -- creatures of myth and legend who bestrode the department when giants walked the Earth -- and Fermi plays this role at Chicago. But having chosen my Chicago scene, I faced a second obstacle: a complete lack of artistic talent. As I am an oldest child, my mother saved all of my kindergarten artwork, and it clearly shows my development as an artist -- in the course of the year I progressed from drawing stick figures in black crayon to drawing stick figures with many colors. And I haven't gotten any further since then. So I enlisted the assistance of my (then) 11-year-old daughter, Lucy, And here is what we (and by "we", I mean "she") produced:

Enrico Fermi, the marshmallow bunny.  The error in the original photo is repeated here -- how's that for verisimilitude?
So did we win the competition?

Thursday, September 15, 2016

Fermi Meets Sagan

My (very) short story, "Fermi Meets Sagan," will be out in the December issue of Analog.  It was inspired by this nonfiction article I wrote for The Conversation website.

Monday, September 12, 2016

The Affinities, by Robert Charles Wilson

I just finished reading The Affinities, by Robert Charles Wilson. Before I discuss my impressions, the usual disclaimer applies: De gustibus non est disputandum. I have only one criterion when I evaluate a work of science fiction -- did I enjoy reading it? So if your own tastes are similar to my own, you might find my comments interesting. Otherwise feel free to ignore everything I say.

My own interests run strongly toward "hard" science fiction, and I am a particular fan of "idea" stories -- these are stories where an amazing speculative idea is central, rather than character, or writing style. I also like clever endings. All of this is much easier to pull off in short fiction than in a novel. These kinds of stories are characteristic (in the golden age) of Clarke and Asimov, and more recently authors like Vernor Vinge and Greg Egan. Stephen Baxter is also someone whose novels I ought to enjoy, but I've never been able to make it through them. Why not?  I haven't got the faintest idea. I warned you that my opinions are totally subjective -- sometimes I cannot even explain them myself. I do like Baxter's short fiction, though.

As I've aged, I've developed a greater appreciation for realistic characters and a more florid writing style. Perhaps this is incipient senility. It's the latter (wonderfully-drawn characters, not senility) that is Robert Charles Wilson's particular strength. When he's able to combine this with a Big Idea (as he did in Darwinia and Spin) the result is some of  the best science fiction I've ever read.

Thursday, September 8, 2016

The Technology is Dead, but the Words Linger On

In my earlier post I talked about listening to a "book on tape."  It wasn't really on tape, of course -- I was listening to the book on CD. I haven't listened to a book on a cassette tape in over a decade. But the expression "books on tape" lingers on, despite the extinction of the actual technology.

There are lots of other words and expressions that have far outlived the original technologies that they refer to. Have you recently "cc'ed" anyone on an email message? That expression refers to "carbon copy" -- a method for making duplicates of typed manuscripts. The typist would insert a layer of carbon paper (coated in dry ink) between two sheets of paper and -- mirabile dictu -- the typewriter would produce identical text on both sheets of paper!

Carbon paper -- it's a messy as it looks

Carbon paper was already on the way out even when I was young -- superseded by photocopiers. Another holdover from the typewriter era is the "carriage return."  This originally referred to slapping a lever whenever the typewriter got to the end of the line, flinging the carriage (the cylinder holding the paper) back to the beginning of the line, while at the same time rotating the cylinder to pull up a new blank line on the paper (clever, huh?)  Typewriters have vanished, but the carriage return (or <cr>) lives on in their digital descendents.  [At this point I should mention that I was required to take a typing class in high school for one semester. At the time, I considered it to be totally worthless, but when computer keyboards became ubiquitous 20 years later, I realized it was the most useful class I had ever taken. I commend my high school for its foresight].

Tuesday, September 6, 2016

What was the Universe Doing at Your Age?

Pretty much nothing, but that's an interesting story in itself.

Let's assume that you're between the ages of 10 and 100 years old (luckily, many things in cosmology depend only on orders of magnitude). When the universe was the same age as you, it consisted of a soup of protons, electrons, helium nuclei, and radiation. But the soup was very hot -- the temperature was a few hundred thousand degrees Celsius. At that temperature, the radiation was actually more dense than the matter!

But in terms of exciting events, nothing much was going on. The two major events that we understand pretty well in the early universe are the formation of some of the light elements when the universe was a few minutes old, and the release of the cosmic microwave background radiation when the universe was a few hundred thousand years old.  In all of the time in between, the universe just expanded and cooled. Or at least we think it did.

Tuesday, August 30, 2016

Origins of an Old Physics Joke

Here's a joke that often makes the rounds of physics departments:

The 3 stages of a newly-published result are

1.  It's wrong.

2.  OK, it's not wrong, but it's trivial.

3.  OK, it's correct, and it's important, but I did it first.

(I think every theoretical physicist has experienced all three of these, although at different times and on different research projects). It turns out that the origins of this joke are more hoary than I could possibly have imagined -- it dates back to a 19th-century scientist!

Wednesday, August 24, 2016

Get Ready for the Great American Eclipse

In just under a year (Aug. 21, 2017) a total solar eclipse will darken the skies across a wide swath of the U.S. Solar eclipses are exceptionally rare events -- the last one in the U.S. that I can remember occurred in 1970 along the East Coast.  Growing up in St. Louis, I had to watch it on TV, but we were promised a Midwestern eclipse in 2017, and I have been waiting patiently ever since then.

There are dozens of websites devoted to this eclipse, but there's a particularly good one at The path of totality passes near or through several major cities, including my ancestral home (St. Louis) and my current residence (Nashville). If you can travel to view the eclipse, do it! And be sure to buy some eclipse glasses for safe viewing. The danger in viewing an eclipse is not so much from looking at it during totality, but when the eclipse is still partial -- the problem is that people start looking at the eclipse before it is really total, or keep looking at it after the totality ends. Just don't! You don't want to permanently damage your eyes. Eclipse glasses are cheap and easy to find -- we've already gotten 20 pairs. I imagine they'll be harder to find and the price will go up significantly as it gets closer to the actual date. We'll be selling ours for $100 a piece on Aug. 20.

Tuesday, August 16, 2016

Life on Earth Began on.... Venus???

In the Golden Age of science fiction, Venus was the jungle world -- full of hot, steamy swamps populated by hot, steamy aliens. Ray Bradbury ("All Summer in a Day") imagined a world of constant rain. C.S. Lewis even set a version of the Garden of Eden on Venus in his novel Perelandra.

But the real-life Venus is no Eden -- it's blanketed by clouds of sulfuric acid (ouch!) with temperatures well above 800 degrees F. The surface of Venus is both dark and hot -- not too different from classical conceptions of hell. And did I forget to mention the atmospheric pressure? It's almost 100 times higher than the Earth's.

A typical Venusian, as portrayed on The Twilight Zone
But it's easy to see why science fiction writers were free to speculate about jungles and swamps all those years -- the surface of Venus is hidden by constant cloud cover (that sulfuric acid again!) making it impossible to probe until the advent of the space program. But now scientists at NASA have come up with a startling new idea: they suggest that Venus was at one time a balmy, hospitable place after all, and possibly suitable for life.

Tuesday, August 9, 2016

New Particle at the Large Hadron Collider: It's Dead, Jim

For the past few months, the world of particle physics has been holding its breath.  The experimental groups at the Large Hadron Collider had reported possible evidence of a completely unexpected new particle with about 750 times the mass of the proton, and everyone was waiting for new data to either confirm or rule out this discovery. In the meantime, theorists churned out hundreds of papers explaining this particle. (I make no claim to moral superiority here -- I didn't write anything on this subject only because it's outside of my specialty). Well, the new data has come in, and the verdict is.... no such particle.

The Large Hadron Collider. Nothing to see here. Please move along.
Which leads to an interesting question: when was the last time that a completely unexpected new particle was discovered at an accelerator? The answer is shocking.

Friday, July 29, 2016

Of Water Worlds and Desert Planets

Everyone learns in primary school that the surface of the Earth is about 70% ocean and 30% dry land. But is there any reason to believe that this is the norm across the Galaxy? In this paper, Fergus Simpson argues that most habitable planets should actually be "water worlds," i.e., planets covered entirely with water.

Friday, July 22, 2016

Dark Matter - Where is it ???

Last month I discussed the experiments using vast tubs of liquid xenon to search for dark matter. It turns out to have been a prescient post, because yesterday the scientists from LUX (a liquid xenon experiment buried deep under the Black Hills in South Dakota) posted their latest results. And they saw.... absolutely nothing.  LUX is the most sensitive experiment of its kind, and these scientists were able to push down upper limits on how strongly the dark matter interacts with ordinary matter by a factor of 4.

So why haven't we detected dark matter yet? It might still be hiding just below the current sensitivity of our experiments. But it's also possible that we're barking up the wrong tree.

Wednesday, July 20, 2016

Popular Culture Down the Memory Hole

Popular culture is by its very nature ephemeral. Today's famous actor or musical hit is tomorrow's trivia question. But some types of pop culture are more ephemeral than others, and there's one area that's vanished so thoroughly that it's left almost no trace at all.

See if you can fill in the blanks:

I'd rather fight than _____
I'd walk a mile for a _____
A silly millimeter _____
You've come a long way, _____

My guess is that everyone over the age of 50 will recognize the answers instantly, and nobody under the age of 40 will have the slightest clue what I'm talking about. So what are the answers?

Thursday, July 14, 2016

Mars, and its Rival

For those of you in the Northern Hemisphere, there's a spectacular sight near the southern horizon in the early evening. ("Spectacular" here is a relative term when applied to the night sky -- I'm not talking Disney-fireworks-over-Cinderella's-Castle spectacular). If you look to the south, you'll see a very bright, reddish-looking object -- that's Mars. And if you look to the left of Mars, you'll see two other bright objects. The lower one also has a reddish hue. It's Antares, a red supergiant and the brightest star in the constellation Scorpio, the scorpion. (Yes, I know that none of the constellations looks anything at all like its assigned name. Aside from the Big Dipper). Antares actually means "rival of Mars," because of its red coloration, so this is a rare chance to compare Mars and its rival right next to each other. I'm afraid I'll have to go with Mars -- Antares is pretty weak competition.

Wednesday, July 13, 2016

Metrology -- the Boring Science

As promised, here is the short SF story I wrote on the topic of metrology, the study of "weights and measures."  It's "Equivalence Principle" and it appeared in the Jan/Feb 2004 issue of Analog. The story itself was inspired by a lecture I attended on string theory -- the speaker emphasized that physics was all about unifying disparate physical quantities, such as time and space, and mass and energy. It just shows that you can write a story about any topic, no matter how seemingly boring...

Monday, July 11, 2016

The Elements Nobody Talks About: Iridium

Do you know anything about iridium? Perhaps you've heard of the Iridium satellites, which were launched to serve as the basis for a satellite phone system. They're so reflective that they occasionally produce "Iridium flares," -- bursts of light that briefly outshine everything in the night sky except the Moon. If you've never seen an Iridium flare, then you should -- they're pretty impressive. The flares are extremely localized, so you need to go to the website Heavens Above, enter your location on the map (scroll all of the way in until you can see your own house!) and then click on the Iridium flare tab on the left. You'll get a list of flares that you can see from your location, including both the exact time they start, and where to look in the sky. Don't waste your time with any of the weak flares -- wait for one that's magnitude -5 or brighter. (In their typical contrary fashion, astronomers denote brighter objects with lower magnitudes -- blame the ancient Greeks).  Be sure to have an accurate time-keeping device -- the flares only last for a few seconds.

What do the Iridium satellites have to do with the element iridium? As far as I can tell, absolutely nothing -- the name just sounded impressive. (Which leads to an interesting question: can you trademark the name of an element?)

So what is the story with iridium? It's one of three sister elements with similar chemical properties; osmium, iridium, and platinum. Platinum is the Cinderella princess of the three -- a "precious metal" used in jewelry -- while osmium and iridium are the ugly step-sisters. But iridium plays a central role in science....

Wednesday, July 6, 2016

Help -- One of our Stars is Missing!

Suppose there were amazingly advanced alien civilizations out there -- aliens capable of harnessing the energy of entire galaxies. (These are the Kardashev Type III civilizations). Surely such a civilization would easy to spot?

I've noticed a surprisingly large number of serious astronomy papers on this subject recently. As you might imagine, nobody has seen any evidence for such a civilization -- if they had seen something, you probably would have heard about it by now. But here's a fun new idea from Beatriz Villarroel and collaborators at Uppsala University: searching for disappearing stars. These scientists compared two surveys of the sky -- one from the US Naval Observatory, based on observations of the sky between 1950 and 1999, and the more recent Sloan Digital Sky Survey. They examined 10 million objects, and found exactly one object in the first survey that seems to have disappeared in the later survey.

Does this mean that an advanced civilization has caused a star to vanish?

Thursday, June 30, 2016

Are There Aliens in our Future?

Avi Loeb, who's one of the most creative people in my field, posted a paper yesterday exploring the likelihood of life in the universe as a function of time. He and his two collaborators argue that life is far more likely to arise in the distant future of the universe than it is today. Why?

Tuesday, June 21, 2016

The Elements Nobody Talks About: Xenon

The inert gasses (helium, neon, argon, krypton, xenon, radon) are the elements you never hear much about. Sure, we worry about radon gas, and helium gets a good workout in balloons, but when was the last time somebody mentioned krypton at a cocktail party? (Come to think of it, when was the last time you actually attended a cocktail party?) The inert gasses are the lazy elements -- they just lie around all day in the hammock and never do anything. If I were an element, I would want to be be an inert gas.

And that applies especially to xenon. Until recently, if you'd asked me about the main uses of xenon, I would have said it was useful primarily in Scrabble. But within the last couple of years, xenon has become one of the most important elements in cosmology.

Monday, June 13, 2016

Robert Heinlein and Intellectual Fads

I just finished the first volume of William Patterson's massive two-volume biography, Robert A. Heinlein: In Dialogue with his Century. It suffers a bit from the curse of too much information; e.g., "Shortly after selling his second story to Astounding, Heinlein feasted on a breakfast of bacon and scrambled eggs. The bacon was crispy, but the eggs were too runny. There was no toast." OK, I just made that up, but you get the picture. I'm being a bit unfair, as the most interesting thing about this book is the detailed picture it paints of pre-WW2 American society, especially Heinlein's life at the Naval Academy and his early career in the U.S. Navy. Like many science fiction readers, I had always thought of Heinlein as a writer with a brief and unimportant stint in the Navy. But Heinlein had planned on a life-long naval career before being forced to retire for health reasons -- I am sure that in a parallel universe somewhere he led the Pacific Fleet to victory against the Japanese.

Patterson also highlights another striking aspect of Heinlein's life -- his tendency to fall for many of the more unusual intellectual fads of his day. While he often presented himself as a hard-bitten empiricist, Heinlein latched onto some of the most bizarre variations of socialism in the 1930s, and he was a big fan of general semantics. What's that? You've never heard of general semantics? But it was all the rage -- or at least it was 80 years ago. Promulgated by "Count" Korzybski, it promoted "non-Aristotelian logic." As far as I can see, its major contribution to Western thought was its use as a basis for A.E. van Vogt's novel, The World of Null-A.

Wednesday, June 8, 2016

New Element Named After Tennessee

I couldn't let the day pass without noting that the International Union of Pure and Applied Chemistry, which certifies the names of newly-discovered elements, has recommended that element 117 bear the name of "tennessine,"  in honor of the joint discovery of this element through work at Oak Ridge National Laboratory, the University of Tennessee, and the efforts of two of my colleagues here at Vanderbilt.

Friday, June 3, 2016

Graduation Season

I journeyed up to the "Garden State" for my oldest son's college graduation this past week. (I've always assumed that New Jersey's nickname was some sort of obscure joke):

The Garden State. Really???
In the course of sending my children through college I have come to this deep revelation, which I will now share with you:

Mothers cry when their children go off to college.
Fathers cry when they can no longer claim their children on their income taxes.

Tuesday, May 24, 2016

Playground Physics

Playgrounds are a great place to learn some basic physics. Or at least they were 50 years ago, before the safety mavens moved in and rebuilt everything in plastic and foam rubber. Take a look at this old seesaw:

The physics lesson is right in the center: the seesaw rested on an open pivot, so that you could just lift it up and move it, making one side shorter than the other. This was a perfect illustration of a lever -- a lighter kid on the longer end could easily balance against a heavier kid on the shorter end. At least until one of them jumped off, sending the other crashing to the ground. But it was the movable pivot that doomed this particular type of seesaw. You can see how easy it would be to get your fingers crushed in the center. I never actually saw this happen, but we all lived in dread of the possibility.

An even more interesting physics demonstration was the old-fashioned merry-go-round:

The game here was to push the merry-go-round as fast as possible, until centrifugal force almost flung everyone off. Disclaimer: we teach all of our college freshmen that there's really no such thing as centrifugal force. The force actually points inward, and it's called "centripetal force." But if our students go on to a more advanced class, they learn that there really is such a thing as centrifugal force, but it's a "fictitious force" --  a force that only appears in an accelerating frame of reference. So when you're flung off the merry-go-round and scrape your legs while sliding across the concrete, you can comfort yourself with the fact that it was only a fictitious force that threw you across the playground.

Thursday, May 19, 2016

Galaxy Quest

I watched Galaxy Quest again the other night. It's a hilarious spoof of Star Trek -- a group of washed-up actors from a cancelled science fiction TV series are mistaken for the real thing by aliens who have intercepted their TV broadcasts and who need their help to defeat their ruthless foes.

Wednesday, May 11, 2016

Chipmunk Delenda Est

I am engaged in an ongoing war with a family of chipmunks that has taken up residence in a narrow strip of ground between my house and our outdoor fish pond. They are perilously close to burrowing through the pond liner, unleashing a thousand gallons of water against the base of my house.

While the chipmunks and I are evenly matched intellectually, I am thus far in the lead, 2-0. But my battle against the chipmunks led me to this scenario:

Imagine that the doorbell rings, and you go to the front door to discover an unexpected package from Amazon. The box is strangely wrapped, and some of the words are misspelled, but you can see that it's stuffed full of money -- some of the cash is leaking out of rips in the cardboard. So you lean over to pick up the box and... thwack! Revenge of the chipmunks.

Friday, May 6, 2016

To the Stars, on a Ray of Light

I gave up on dreams of interstellar travel a long time ago. I outgrew them, just as I outgrew the Tooth Fairy and the Easter Bunny. And then last month, along came this paper by Philip Lubin from the University of California at Santa Barbara, claiming that interstellar travel is feasible with existing technology.

Wednesday, May 4, 2016

Before there was the Internet, there was....Semaphore!

Boy Scouting and I didn't really get along too well. I hated camping, and I thought nature was best viewed from the comfort of a hotel room. None of this was helped by the fact that my Boy Scout Troop was the most amazing collection of losers and goofballs ever assembled under the Boy Scout umbrella. At our local camping competitions, we would invariably finish last. Our scoutmaster became so enraged at one of our meetings that he threatened to walk out and never come back if we didn't settle down. We took this as the usual empty adult threat (did your dad ever really turn the car around and drive back home on the way to a family vacation?) So we kept up our antics. Much to our surprise, our scoutmaster did walk out of our meeting, got into his car, and drove away, never to be seen again. Thus ended my career in Scouting.

But I did learn a few worthwhile things in the Boy Scouts. I can tell the difference between venous bleeding and arterial bleeding (the difference is that arterial bleeding means you're going to die). I can identify poison ivy -- most of the time, anyway. And best of all, I learned semaphore.

Semaphore was an early version of the internet. Packets of information, called "letters" were encoded as positions of two signal flags and transmitted through the air over literally tens of yards. Transmission rates of 1-2 bytes per second were possible.  (Quiz: with two signal flags, and eight different flag positions, how many different letters can be encoded? The two flags cannot occupy the same position).

Semaphore plays a role in L. Sprague de Camp's classic novel, Lest Darkness Fall. The protagonist finds himself hurled back in time to the last days of the Roman Empire, and he sets about trying to stave off its collapse. It's an interesting idea -- what are the "doable" technological improvements you could introduce to the ancient world? He starts with Arabic numerals and eventually introduces a system of cross-country semaphores to allow for rapid communication across the empire. But this raises an interesting question -- why didn't ancient civilizations, or for that matter, any pre-telegraph civilizations, use systems of semaphore towers?

Monday, April 4, 2016

Six Degrees of Star Trek

As I mentioned a few months ago, I spent much of last year plowing through Herman Wouk's massive two-volume WWII epic, The Winds of War and War and Remembrance. So having finished it, I naturally had to rent the made-for-TV miniseries. Last night, while watching part 3, I noticed that the actor playing Congressman Lacoutre, a rather obnoxious isolationist, looked vaguely familiar... Could it be? Yes, of course it was the actor Logan Ramsey, who reached the pinnacle of his career playing Proconsul Claudius Marcus in the Star Trek episode "Bread and Circuses" (the Roman Empire episode).

Your decision, Proconsul.

This suggests an obvious game: Six Degrees of Star Trek, based on the well-known Six Degrees of Kevin Bacon, in which the participants begin with an actor and try to establish a series of co-star links back to Kevin Bacon. Anyone who has appeared in Star Trek has a Star Trek number of 0, while actors who have appeared in other shows with those actors have a Star Trek Number of 1, and so on.

Let's try an example: Patty Duke, who died last week.

Friday, April 1, 2016

April Fools' Day in Physics

It's April Fools' Day, so as usual, a number of prank papers have blossomed on the physics preprint arXiv -- this year produced a bumper crop.  Here are the ones that I was actually able to identify:

Wednesday, March 23, 2016

Children's SF and Fantasy that I Missed the First Time Around

While I was a voracious reader as a child, there were some major gaps in my reading -- children's books that I only discovered or read much later, when I had children of my own. In many cases these books, sadly, just don't "work" when you get older, although there are a few I appreciated all the more:

The Phantom Tollbooth (Norton Juster).  When I first read this book to my own children, my initial reaction was shock -- shock that I had never even heard of it when I was a kid, and a shock of recognition -- the author's sensibility is so similar to my own that I felt like I was reading something that I could have written myself! (In fact, I did write a similar story for my 7th grade English class, called "The Land of the Numbers." Sadly, no copies survive).  Highly recommended.

Monday, March 21, 2016

Vocabulary Trivia Quiz

The "new SAT" made its debut earlier this month. Part of the redesign included a de-emphasis on obscure vocabulary words, since it is well-known that college students no longer need to read multisyllabic words.

I am sure that this loss was deeply felt by many of us, so to make up for it, I am offering a one-question vocabulary quiz for today.  Here's the question:

Which of these words is not like the other?  One of these words just doesn't belong. Which one is it? (Extra credit if you can define all of the words).

A.  Jacobite
B.  Jacobin
C.  Jacobian
D.  Jacobean

Answer after the break...

Friday, March 18, 2016

Quantum Mechanics and Board Games

While I am a fan of nearly all board games, I've just never gotten excited about Go, the subject of the most recent human-computer smackdown.  But a couple of days ago, Andre Ranchin proposed an amusing variant of Go -- one that incorporates quantum mechanics!

Thursday, March 17, 2016

Will Computers ever be Self-Aware?

Will computers ever achieve a form of consciousness?  This is such a huge topic in science fiction that I cannot begin to do it justice.  The roots of the idea go all of the way back to Frankenstein.  And it bubbles up again every time there is some new milestone in artificial intelligence, such as the recent victory by AlphaGo in its match with Go champion Lee Seedol.

Personally, I think it's impossible for a computer to achieve self-awareness. Consider the Turing test, in which a computer is challenged to imitate a human in conversation. I actually wrote a computer program to mimic human interaction back when I was in high school, modeling it on the famous ELIZA program, which was supposed to imitate a psychotherapist. The remarkable thing is not that I did this back in the 1970s, writing in BASIC, but that I actually saved the output for 40 years. So here's an excerpt from my conversation with my own computer program. You'll see that the computer displays a bit of an adolescent male perspective.. The computer responses are in italics:

Computer:  Welcome to my office. What is bothering you?

Me:  I have these weird dreams.

Would you like to discuss dreams?



Because I have weird dreams.

Why do you keep talking about dreams?

Because they bother me.

I'd like to talk about dreams.

Good.  Say something intelligent for a change.


I'm tired of talking to you.

Why to you want to talk about me?

I don't.

People like you should be locked up.

You are a mere computer and have bad judgment.

Would you like to discuss computers?

Yes.  Do computers have feelings?

That's an interesting question.  What made you think of it?

Since you are a computer, you should know the answer.

I'd rather talk about computers than my answer.

What's that supposed to mean?

Why do you ask such a question?

You are so stupid.

I am not!!

Yes, you are stupid.

Yes, you are stupid, too.

I'm tired of talking.

I really don't think that you are.

How would you know?

I'm asking the questions around here, not you.

Monday, March 14, 2016

Pi Day

In honor of Pi Day, I direct your attention to this "scientific" paper, which I posted to the physics preprint arXiv on April 1, 2009:
"Time Variation of a Fundamental Dimensionless Constant".
For those of you outside the world of physics, the "arXiv" website is where most physicists post their papers while they are waiting for them to appear in a scientific journal.  It's a little-known fact that the managers of this site have tacitly allowed April Fools' Day papers to appear over the years.  You can search them out, but they are hard to find.

Monday, February 29, 2016

Leap Years and How Scientists Tell Time

I couldn't let Feb. 29th go by without commenting on leap years, especially since I have no expectation that this blog will still be around four years from now. Leap years originate in astronomy -- the length of the year (the time it takes the Earth to go around the sun), is not an even number of days (the time it takes the earth to rotate on its axis). The length of the year is roughly 365.2422 days. Lucky for us, the fractional part of the year (0.2422) is almost equal to 0.25 (or 1/4), so we can fix things by adding 1/4 of a day every year, or one day every four years. This "fix" was introduced by the ancient Romans, and it works pretty well, but it's still not perfect. The Gregorian calendar fixes the fix by taking away leap days every 100 years (so, for instance 1800 and 1900 were not leap years) and then adding them back in every 400 years, so 2000 was a leap year. Our leap year in 2000 is something we won't see again until 2400! This gives us a length of the year equal to 365 + 1/4 - 1/100 + 1/400 = 365.2425 days, which means the calendar will be off by one day every 3333 years -- not too shabby!

Calendar reform had a symbiotic relationship with the infant science of astronomy. It's really just a weird coincidence that a simple leap year works so well, but not well enough that it didn't need to be fixed later on. Would science have developed any differently if the year were more exactly a simple fraction of the number of days, so that the Gregorian reform had not been necessary? And what if the opposite had been true? What if the year weren't anywhere close to a simple fraction of the number of days? Would that have led to much greater calendrical confusion over the centuries?

Given all of this confusion, what unit of time do scientists use in their own work?  Days? Years? Hours? Minutes? The answer is none of the above.

Friday, February 26, 2016

The Flat Universe Society

In my peregrinations around the Internet, I have discovered not one, but two websites devoted to the Flat Earth Society:

I think one is a splinter group from the other. I bet they hate each other.

But why limit ourselves to a binary choice? Why does the alternative to a round Earth have to be a flat Earth? Let's be creative and think of other possibilities.

Maybe the Earth is actually shaped like a torus (a gigantic donut):

This is even better than a sphere -- now there are two different ways to go around the world! You can sail around the outside of the donut, or you can circle the world through the donut hole.

Or maybe the surface of the Earth has negative curvature, like a saddle or a Pringles potato chip:

Of course, this isn't what the Earth looks like. But it's what the entire universe might look like.

Tuesday, February 23, 2016

Gravitational Radiation and the Search for Extraterrestrial Intelligence

With the first direct detection of gravitational radiation by LIGO, we've entered a new era in science. Gravitational wave astronomy promises to be the most exciting field in the physical sciences for the next decade. So should we start looking for signals from ET in this data?

Wednesday, February 10, 2016

First Detection of Gravitational Radiation?

It's totally irresponsible for scientists to spread rumors on the Internet, so I will wait until after the break to do so.

Tuesday, February 2, 2016

Dell Award for Undergraduate Science Fiction Writing

This past fall marked the third time that Professor Jay Clayton and I taught our Vanderbilt seminar on science and science fiction. As a final exercise, the students usually choose to write their own short stories. (They also have the option of writing a "popular science" article or a critical essay, but only one student has chosen this in the entire history of the class!) We've always entered the best of the students' stories in the competition for the Dell Award for undergraduate science fiction writing. This year, our students took first place and third place in the competition!

Monday, January 25, 2016

Thought for the Day: Snow Edition

Nashville received a backhand blow from the storm that knocked out the East Coast: we got 8 inches of snow (the heaviest snowfall since I've lived here), which completely paralyzed the city. Nashville's method of snow removal is called "solar power." We lost electricity for several hours on Saturday morning and watched helplessly as the temperature inside the house dropped about a degree every hour. Power was restored before it got too uncomfortable, but this led me to the following thought experiment. Suppose that all of our technological infrastructure (electricity, gas, cable TV) collapsed for a month in the middle of the winter. Which one of these people would you want at your side to help you survive?

Thursday, January 21, 2016

The Kardashev Scale for Extraterrestrial Civilizations

Back in the 1960s, the Soviet scientist Nikolai Kardashev proposed a scale to measure the technological level of extraterrestrial civilizations. I was reminded of his work by this paper, which appeared today. Here is an explanation of the Kardashev scale, with some minor additions of my own:

Tuesday, January 19, 2016

The Historical Memory of Children

I'm too young to remember the day that John F. Kennedy was assassinated, but I remember the assassination of Martin Luther King with crystal clarity. I was 9 years old at the time, attending a small Catholic school in St. Louis. The morning after King was assassinated, all of the nuns at my school were deeply upset, which puzzled me, because I was under the impression that Martin Luther had been assassinated. A little historical knowledge is a dangerous thing, and we forget what it was like to be young and have such a distorted understanding of history.

Wednesday, January 13, 2016

Happy 50th Anniversary, Batman!

Yesterday was the 50th anniversary of the premier of Batman, the television show. It's difficult today, within our fractured popular culture, to appreciate what an overwhelming phenomenon this show was at the time, but I can give one example from personal experience.

Tuesday, January 12, 2016

When Young People Watch Old Movies

In preparation for taking my children to the latest Star Wars movie, we pulled our copies of the original Star Wars trilogy out of storage for the kids to watch. And what did my kids think of them? One main comment: the special effects weren't very good.

Now when I was a kid, special effects were downright awful, and yet I somehow managed to look past them to enjoy all of the classic SF movies of the 50s and 60s. I know this sounds like the typical complaints of a grumpy middle-aged man about how when I was a kid ... a line of argument that goes back, I believe, to the ancient Sumerians.

Friday, January 8, 2016

How to Raise a Scientist in the Xbox Age

I had another op-ed in the Wall Street Journal a few weeks ago, entitled "How to Raise a Scientist in the Xbox Age."  You can't read it unless you are a subscriber -- the Wall Street Journal is behind a paywall that makes the Berlin Wall look like a speed bump -- but the article basically details my experiences growing up as proto-scientist in the 1960s and 70s.