Thursday, December 31, 2015

Puzzling Expressions from Science

Many expressions from science have entered our everyday vocabulary, but sometimes in ways that are puzzling. Here are a few that I have wondered about -- perhaps some of you can explain them:

1.  Guinea pig. This is now a colloquial expression for any experimental subject. But biomedical research is performed mostly with rats and mice. So instead of saying, "Can you be my guinea pig for this recipe?" why don't we say, "Can you be my rat for this recipe?" Were guinea pigs much more important in research fifty or a hundred years ago? If so, it certainly wasn't for ease of breeding. We used to own a guinea pig, and they do not "breed like rabbits" -- more like pandas. I should note that the term "lab rat" seems to be entering the popular vocabulary, so maybe it will eventually displace "guinea pig."

Monday, December 28, 2015


So I finally got to see Star Wars VII. (Why is it that only Star Wars movies and Super Bowls rate Roman numerals?) Of course, Star Wars isn't really science fiction -- it's a fantasy set it space -- but I really enjoyed the first three Star Wars movies (or as my children would say, the second three movies).  I would rank the newest Star Wars offering well below the first three (i.e., the second three), but much better than the second three movies (i.e., the first three). At first I enjoyed the constant references to the first (fourth) movie, but after a while it became apparent that the entire film was just that -- a remix of the original Star Wars, which made it all too predictable. And why did the bad guy come across as an unpleasant Star Wars fan-boy who looked and sounded like he had just stepped out of a Jane Austen film?


Wednesday, December 16, 2015

New Names Announced for Exoplanets and Stars

The International Astronomical Union (IAU) has just announced the official new names for a large number of exoplanets (i.e., planets orbiting other stars). You can read the full list here. (Thanks to my colleague Susan Stewart of the US Naval Observatory for pointing this out). The IAU is the organization that has the authority to confer official names on extraterrestrial objects. That place you paid to name a star after your girlfriend does not have this authority. The IAU had some sort of competition involving nominations from the public, which you can read about on their website.

This list will be of particular interest to science fiction writers out there -- it gives a whole bunch of new names for nearby planets. (For fictional planet names, you really can't beat Larry Niven's Known Space series.  His planets include We Made It, Jinx, Plateau, Home, and Down). But I do have one problem with the IAU list -- they also renamed a bunch of stars! For some stars, it's a clear improvement.  HD 149026 has been named "Ogma" (much easier to remember), while PSR 1257+12 (not an easy name to remember) is now called "Lich." But they renamed some fairly well-known stars as well. The prime example is epsilon Eridani, which is now supposed to be called "Ran." But epsilon Eridani is a famous star, visible to the naked eye. Maybe I'm just annoyed because I used it in a story that I sent off a few weeks ago. But I'm sure it's been used in countless other SF stories as well. And frankly, Ran just doesn't sound as good.

Friday, December 11, 2015

Class Blog for Science/Science Fiction Seminar

Yesterday was the last day of classes at Vanderbilt, and so the last day of our seminar on science and science fiction. We had a great group of students this year, and the class was a joy to teach. As part of their class assignments, the students were required to write blog posts periodically. The result was an eclectic mix of reflections on the readings for the course, discussion of general issues in science fiction, and original science fiction from the students. I encourage you to take a look at it; the URL is

Wednesday, December 9, 2015

Historical Fiction vs. Historical Science Fiction

Although I enjoy reading about history, and I've been an inveterate board wargamer for 40 years, I've never enjoyed historical fiction. On the other hand, I'm an avid fan of historical science fiction (which probably includes about half of all time travel stories ever written -- I particularly like the works of Poul Anderson), and I also enjoy historical fantasy, especially the books by Tim Powers (more about him later). But I think I finally understand this apparent disconnect.

I was recently persuaded by this laudatory article at The Atlantic to take a crack at Herman Wouk's massive two-volume series on World War II, The Winds of War and War and Remembrance. Wouk is often compared to Tolstoy, and since I never read War and Peace, I figured Wouk's books would make an acceptable substitute.  Plus I find World War II much more interesting than the Napoleonic era -- it's easier to sort out the good guys and the bad guys. Herman Wouk, by the way, is still alive, at the age of 100.

Now I am going to explain my issues with historical fiction, but before I do so, I have to summarize part of the plot of The Winds of War. Warning: there are spoilers after the break.

Monday, December 7, 2015

Why is the Universe Mathematical?

Why is our scientific description of the universe based on mathematics? If you've taken physics or chemistry classes, it might seem obvious that the laws of nature are mathematical, but in fact it's a very deep mystery. I should admit right from the start that I am not a particular expert on this subject, but since this is a blog, I am entitled to spout off about all sorts of things that I know nothing about. Caveat emptor. By the way, I also don't speak Latin. I just use it to make myself appear smarter than I really am.

Eugene Wigner, who was one of the great figures in quantum mechanics, was one of the first people to think about this problem. He wrote a famous article on it:  "The Unreasonable Effectiveness of Mathematics in the Natural Sciences," which you can read here.  But why is this even a mystery? The way we learn mathematics in school obscures the true nature of math. In grade school and high school, math is firmly embedded in physical reality -- it's a way of solving real-world problems. We learn arithmetic in order to balance our check books (does anyone besides me do that anymore?) and we learn algebra in order to determine the age of our friends, like Suzy, who is twice as old as Jim was when Jim was as old as Suzy is now.  But "real" mathematics, as practiced by professional mathematicians, is nothing like that. Mathematics involves the construction of increasingly complex mathematical structures, which seem to have no basis in physical reality. If you doubt my view, take a look at a random entry at the Mathworld website.  And yet abstract mathematical structures frequently turn up in physical theories, often decades after they were first invented. Differential geometry, which examines curved spaces that seem to have no relation to the physical universe, turns out to be the basis of general relativity (whose centenary we are celebrating this month). Abstract algebra (not the algebra you learned in high school, but things like group theory and linear algebra) lies at the foundation of quantum mechanics. So why do these inventions of mathematicians turn up so reliably in physical theories?

Thursday, November 26, 2015

Woodrow Wilson Trivia Question

Some of you might have noticed the recent kerfuffle about the position of Woodrow Wilson at my alma mater, where it seems like every other building is named after him. The reason for all of this Wilson hagiography is that Wilson was not merely a graduate of Princeton who became president of the United States, but that he was also a faculty member at Princeton and, ultimately, president of the university itself.

As I was contemplating the fact that Wilson was the only university president ever to become president of the United States, I realized that his career path was not unique. There is one other man who served as a university president before being elected president of the U.S. Can you name him? (Hint: like Wilson, he was the head of an Ivy League university).

Tuesday, November 24, 2015

Could We Still Exist if the Constants of Nature Were Different?

Physics is characterized by a handful of "fundamental constants."  For instance, the gravitational constant, G, tells us the force of gravity between different masses.  Similarly, the "fine structure constant" gives the electric force between two charges.  Does our existence depend on the values of these constants?  If they were different, could life still exist?

Tuesday, November 17, 2015

Probability and Statistics in Science Fiction

My previous post on mathematics in science fiction had a serious omission -- I ignored probability and statistics. These two subjects are often lumped together, but they are, in a way, opposites. In probability, you know the rules of the game ahead of time (I roll a die, and each number from one to six is equally likely) and you have to calculate the odds of various outcomes (how likely is it that I will roll three sixes in a row?)  Statistics is just the opposite:  you are given the outcomes and are trying to figure out the rules of the game. If you have a bunch of "data", what is the likelihood that they were produced from a particular model of the universe? In his book Numerical Recipes, Bill Press and his collaborators describe statistics as "that gray area which is surely not a branch of mathematics as it is neither a branch of science."  I couldn't agree more.

Probability is clean and precise, and I really enjoy it.  I've written several papers about the pattern of galaxy clustering in the universe (technically, this is called the "large-scale structure" of the universe) based largely on different aspects of probability theory.  Probability is my friend.

Statistics, on the other hand, is not my friend.  It's a necessary evil, like a decennial colonoscopy. Statistics is the Norse trickster god Loki -- it's slippery and untrustworthy.  There are even different sects within statistics whose members base their analyses on completely different fundamental assumptions.  For example, you can be a Bayesian or a frequentist -- these two groups fought an inconclusive war that devastated Germany in the 17th century.  (By the way, don't believe everything you read on the internet). For a less jaundiced and undoubtedly more accurate view of statistics, read the various posts on Michael Flynn's blog, such as this one.

Tuesday, November 10, 2015

Our Linguistic Debt to Chickens

There are four chickens living in my back yard. How did they get there? What road did they cross to get to my yellow slide? It happened in much the same way that I ended up with a dog: I returned home from work one day and discovered that we had adopted a small flock of chickens. So I am now the proud owner of a Metro Public Health Department Domesticated Hen Permit.

Once, after asking my kids if the chickens were "cooped up" for the night, and thinking about the "pecking order" that the chickens had established, I realized how many everyday English words and expressions we owe to chickens, and how accurately they describe the actual behavior of chickens.

Monday, November 9, 2015

No Radio Signals from KIC 8462852

Well that didn't take long. The SETI folks used the Allen Telescope Array to look for radio emissions from the star KIC 8462852 -- that's the star I discussed last week that shows an unusual pattern of dimming and brightening. You can read the scientific paper here. (They've got to find a shorter name for that star. How about KIC MEE?). So what did the SETI investigators hear over the radio?

Friday, November 6, 2015

Sailin' Through the Solar System

I first encountered the idea of solar sails in the Arthur C. Clarke story, "Sunjammer."  Yesterday, Les Johnson came up from the Marshall Space Flight Center in Huntsville to give an excellent talk on this topic -- I learned a few fun things I hadn't known before.  But first, a trivia question:  Do solar sails operate by catching the solar wind?

Wednesday, November 4, 2015

Mathematics in Science Fiction

Are there any examples of science fiction in which math plays the central role?  Before examining that question, let me pose a simpler one: is mathematics a branch of the sciences, like physics or astronomy?

Monday, November 2, 2015

Have We Discovered a Dyson Sphere Under Construction?

Many of you have probably seen this article over at The Atlantic.  The basic story is that the Kepler mission, which is designed to look for planets orbiting other stars, has turned up something very strange.  And no one is exactly sure what it is.

Wednesday, October 28, 2015

Best. Comic Book. Superhero. Ever.

Many years ago, when I was still working at Ohio State, I had the opportunity to have lunch with Steven Weinberg.  For those of you not familiar with his work, Weinberg is one of the towering figures of 20th century physics.  He shared the 1979 Nobel Prize for his role in the development of the unified theory of electromagnetism and the weak force, a key component of what is now known as the Standard Model of particle physics (yes, it's capitalized).

During lunch, the conversation turned, as it so often does among Nobel laureates, to the subject of comic books.  Weinberg opined that when he was young, parents wouldn't let their kids read comic books, because they were "trash," but these days most parents would be thrilled if their kids read anything at all, including comic books.

So are comic books a form of science fiction?  Of course they are, because they draw on many of the same ideas and themes as mainstream science fiction.  And of course they're not, because a science fiction snob like me will never admit that books with pictures and conversation bubbles should be placed among the pantheon of science fiction.  Yes, I know that comic book conventions regularly outdraw science fiction conventions by factors of 10 or 100 in attendance  Let's not talk about that.

Monday, October 19, 2015

Random Thoughts on The Martian (the Movie, not the Book)

I saw The Martian over the weekend and enjoyed it a lot. I particularly appreciated the fact that the plot did not lurch from one heart-stopping crisis to another. I won't belabor the science issues in the movie, since those have already been widely discussed on the Internet. The biggest one has to do with the Martian "storms." The atmosphere on Mars is so thin that it wouldn't be capable of the kind of death and destruction you see at the beginning of the movie.

Also, the gravity on Mars is much lower than on Earth, but this only becomes apparent near the end of the movie, when Matt Damon begins bouncing around a lot more. Or maybe he just lost a lot of weight from his starvation rations.

Friday, October 16, 2015

Fantasy Physics League

Fantasy sports leagues have been in the news lately, and not in a good way. There have been scandals involving "insider trading," and Nevada is in the process of classifying fantasy sports as gambling. So what should you do if the Feds shut down your fantasy sports league? Try fantasy physics instead!

Thursday, October 8, 2015

College Admissions: A Story

I have an Op-Ed out in today's Wall Street Journal on the subject of college admissions -- I was driven to write it by my experiences with the admissions process as child number three has reached that stage. When my oldest child applied for college, my exasperation took the form of a short story, "The Common App", that was published in Nature.  If you'd like to read it, follow this link.

Tuesday, October 6, 2015

Physics Nobel Prize Trivia

The Nobel Prize in physics was announced today, so this is a good time for Nobel Prize trivia.

What Nobel laureate was sentenced to prison for war crimes?  Hint: he has an "effect" named after him.

Monday, October 5, 2015

Gregory Benford Talk at Vanderbilt this Thursday

I wanted to remind those of you in the Nashville area that noted science fiction writer and scientist Gregory Benford will be presenting our physics colloquium this Thursday, Oct. 8, at 3:00 in Stevenson 4327. The title of his talk is "Our Next Century in Space." The talk is free and open to the public.  Parking at Vanderbilt, however, is very much not free and barely open to the public. There are pay parking spots on the ground floor of the 25th Avenue Garage, and also metered parking on the street in front of the VA hospital (both a short walk to Stevenson Center). The metered parking has a two-hour limit. I believe that there is also free on-street parking once you get far enough east of campus, but I don't know how far east you have to go. Maybe Knoxville.

Tuesday, September 29, 2015

Cosmology in Science Fiction

Almost everyone loves to hear about cosmology. Public lectures on the subject pack in large and enthusiastic audiences.  And what's not to like?  Cosmology deals with the deepest questions in science: the beginning of the universe, the end of the universe, and everything in between. Recent years have seen numerous breakthroughs in our understanding of the universe, and yet the remaining mysteries, like dark matter and dark energy, provide tantalizing clues that much remains to be discovered.

So cosmology ought to figure prominently in science fiction, right? Actually, not so much. And I think there's a very good reason for this.

Thursday, September 24, 2015

The Physics of Popes

In honor of the visit of Pope Francis to the United States, I want to talk a bit about popes and antipopes. But what, you may ask, is an antipope? An antipope is anyone who falsely claims to be the pope. For instance, the papal claimants residing at Avignon during the Great Schism of the 14th century are considered to be antipopes. This leads to a further question: what happens when a pope meets an antipope?

The answer: they annihilate and produce two Protestants. Because you have to conserve Anglican momentum.

Wednesday, September 23, 2015

Why I Never Liked Ray Bradbury When I Was Growing Up

I grew up in the 1960s.  We were the last generation who could run loose in the neighborhood from Saturday morning until dinner time. Our summers were aimless affairs, devoid of any parental organization, as long as we showed up for school in September. But what does all of this have to do with Ray Bradbury?

Monday, September 21, 2015

Shakespeare and Science Fiction

In class last week, one of the students wanted to know if there were any works of science fiction based on Shakespeare's plays. Only one obvious example came to mind.

Friday, September 18, 2015

Neanderthals, Genetics, and Intelligence: Were our Ancestors Smarter than Us?

You know the stereotype:  the Neanderthals were primitive knuckle draggers -- they might have been stronger than us, but we used our superior intellect to outcompete them and drive them to extinction. Ted Kosmatka, in his short story, "N-words," neatly turns this picture on its head.

Wednesday, September 9, 2015

Vanderbilt Course on Science and Science Fiction

The semester here is well underway, and I am teaching (with my colleague Jay Clayton from the English Department) an honors seminar on science and science fiction. Each week is based around a different theme (time travel, quantum mechanics, prediction of the future), with corresponding stories assigned. Then we discuss both the scientific issues (Does physics rule out time travel?  Why can't you travel faster than light, and what are the implications for interstellar travel? And what's deal with Schrodinger's cat?) and the stories themselves.  It's a unique blend of hard-core science and literature (as the name of the course suggests).  This is the third time we've taught this course, and I think we're finally starting to get it right.  You can look at the class blog at  There's a link there to the class syllabus, if you'd like to see what we are reading.  All in all, it's the most fun class I've ever taught. And of course, this blog itself grew out of my teaching that course.

Monday, August 31, 2015

Computer Nostalgia c. 1970

Growing up in St. Louis, one of my favorite places to visit was the local science museum.  This wasn't the huge St. Louis Science Center that currently straddles I-64 in the heart of the city -- it was just a couple of small buildings in a park in the suburbs.  But to my 10-year-old self, it was a wonderland.  There was the "Hall of Matter" with a UV light to make rocks fluoresce, a microscope to read writing on the head of a pin, and a large mechanical eye that could be distorted with a lever to illustrate myopia. And one day, some time around 1970, my family showed up at the museum to find a travelling exhibit with lines snaking across the room.  What marvel could have attracted such huge crowds?

Tuesday, August 25, 2015

Good News Everyone! The Earth Won't Go Flying Out of the Solar System

One of the most memorable science fiction stories I read as a child involves a family holed up in a makeshift shelter after a passing star has flung the Earth out of its orbit. One of the children has to go out every day with a bucket and bring back the day's supply of frozen oxygen to be thawed out in the shelter. Despite remembering the story so vividly, I completely forgot the title and author, but an Internet search reveals them to be: "A Pail of Air," by Fritz Leiber.

But this is just fiction, right?  The Earth couldn't really be flung out of its orbit, leaving us to freeze to death in the icy blackness of space. Or could it?  Well, it's complicated....

Let me digress a bit before getting to the punchline. The laws of physics mostly boil down to collections of differential equations, but these come in two flavors: linear equations and nonlinear equations. Linear equations are, in the parlance of physics, "well behaved."  They are the obedient children who do their homework on time and don't talk back to their parents. But nonlinear equations are the bad boys of physics. They smoke. They drink. They probably carry switchblades. More to the point, they exhibit "chaotic" behavior -- a tiny change in one place can quickly grow to produce huge consequences somewhere else. The classic example is the "butterfly effect": a butterfly flapping its wings in California could theoretically alter the weather so much that five years later, a hurricane strikes Florida. And here's where things get interesting. The equations governing the motion of the planets around the Sun are nonlinear and could, in principle, exhibit just this kind of chaotic behavior. The planets could orbit the Sun happily for billions of years until a small change in their orbits gets larger and larger and expels one or more planets entirely.

Wednesday, August 19, 2015

The Peculiar Writing Style of Scientific Journals

Most scientists I know are very good writers. But you'd never know it from the articles they publish in scientific journals, where the prose is turgid, convoluted, and downright scary. I'm not talking about popular science magazines like Scientific American -- I mean the journals where scientists publish their latest results -- places like Nature and Science, or, in my own field, Physical Review and Astrophysical Journal. These journal articles are the currency in which scientific research is measured -- they get us tenure, government grants, and an unrealistically inflated sense of our own importance. And the writing style in these journals is very, very odd.

Monday, August 17, 2015

Evading the Speed of LIght: Karl Schroeder's Lockstep

Just when you thought there was nothing new to be said about evading the speed limit imposed by relativity, science fiction comes up with a completely original possibility. I just finished reading Karl Schroeder's Lockstep, which proposes yet another way to get around Einstein's cosmic speed limit. Lockstep was serialized in Analog about a year ago and has recently been published as a novel.

Wednesday, August 12, 2015

The Wacky Names that Scientists Give Their Experiments

One way in which science fiction falls short in depicting "genuine" science is in the names that scientists give their experiments. Experiments in physics or astronomy are often labeled by whimsical acronyms that spell out the names of animals or cartoon characters, or that produce clever puns. You won't see this very often in science fiction, because science fiction writers' hands are tied -- if their fictional scientists emulated real life and gave their experiments silly names, the readers would automatically assume that the story was intended to be humorous. This is one time that truth really is stranger (or at least funnier) than fiction.  (One exception is Larry Niven, who somehow manages to give his planets and alien races playful names in otherwise serious stories).

I was reminded of this at the physics conference I attended last week. One of the speakers presented a new experiment, called "Project 8." It's designed to measure the minuscule mass of neutrinos by detecting radiation from electrons ejected with the neutrinos in radioactive decay. But why "Project 8"?  Were the first 7 projects abject failures? It reminded me of a bizarre Japanese cartoon that I used to watch as a kid: Tobor, the 8th Man, which played endlessly on after-school TV when I was growing up in the days before Sesame Street came along and ruined children's television. The 8th Man was a superhero cyborg, who, when he got into trouble (which happened in every episode), would smoke "energy cigarettes" to recharge his powers. Energy cigarettes??? What was he really smoking? You can check out the unforgettable theme song (which I still can't get out of my head) here.

But back to the issue at hand. After the director of Project 8 finished his talk, I asked him where the name of the experiment came from. He told me that he made it up out of thin air! He was tired of names of experiments composed of silly acronyms. I have to admit that it certainly sounds cool.

What are some of the other whimsical names of physics and astronomy projects? Here are just a few:

Monday, August 10, 2015

Science Research Funding: A Story

I was at a physics conference at the University of Michigan last week, and, sadly, I spent more time thinking about research funding than about the research itself. But it reminded me of this story of mine, which appeared in the April, 2008, issue of Analog. It's the only science fiction story I know of that hinges on the topic of research funding! That's what happens when scientists write science fiction -- you learn what really obsesses them. One of the characters is loosely based on a real person who spent time at the National Science Foundation -- those of you familiar with my own research field should be able to spot him.

Tuesday, August 4, 2015

If We Blew up the Earth, Would Anybody Else Notice?

That question was raised last week in a scientific paper by Adam Stevens, Duncan Forgan, and Jack O'Malley-James. They're really interested in the opposite question: if a distant civilization destroyed itself, would we see any evidence of it? This question arises because one of the answers to the Fermi paradox (why don't we see any other civilizations out there?) is that advanced civilizations tend to destroy themselves, either accidentally (oops, I dropped my hammer on that big red button) or on purpose (I've genetically engineered a virus that kills only annoying people....)

Friday, July 31, 2015

As You Know, Bob: Conveying Information in Science Fiction Stories

One of the fun things about venturing into a completely new field is learning all of the jargon. Physics, of course, has lots of it, but so does science fiction writing. And one of the first phrases that a neophyte writer discovers is "As You Know, Bob."  What's that all about?

Wednesday, July 29, 2015

Classical Mechanics: an Experiment You Can Try at Home

Classical mechanics is the branch of physics that deals with bodies in motion: velocity, momentum, forces, acceleration. And it can be pretty boring. Let's face it --  none of us went into physics because we fell in love with blocks sliding down inclined planes, with or without friction. We went into physics to learn about black holes, quantum mechanics, or the fate of the universe. But classical mechanics is the basis of all of the rest of physics, so it's what everyone studies first. And, unfortunately, for many people it ends up being their only formal contact with physics.

But even in classical mechanics there are interesting byways and surprising results that most people are unaware of.  Here's a cute experiment you can easily do at home that illustrates one of these unexpected results.

Monday, July 27, 2015

Scientists who Write Science Fiction

Gregory Benford, the science fiction writer and physicist from UC Irvine, will be presenting our physics colloquium at Vanderbilt in October -- the talk is free and open to the public, so drop in if you are in the area. Benford belongs to that rare breed of active research scientists who have also carved out a career in science fiction. "But wait!" you say, "What about Isaac Asimov -- he had a Ph.D. in chemistry. And Robert Heinlein and Arthur C. Clarke both had technical backgrounds." All true, but all of these guys, and many others like them, left science to pursue a writing career. In fact, the most famous of these is probably Michael Crichton, who is actually "Dr. Crichton" (with an M.D.) He was conducting postdoctoral biomedical research while launching his writing career. The fact that many people don't think of him as a scientist turned science fiction writer is probably because many SF purists would not consider his work to be "true" science fiction (and some physical scientists would not consider biomedical research to be true science!)

Conversely, many scientists have dabbled in science fiction, writing a few short stories or one or two novels, without ever intending to make a career out of it.  I would certainly put myself in that category. In my own field of astrophysics, there's Don Clayton, who's famous for his work on nuclear reactions in stars, and Craig Wheeler, who works on supernovae.

All of which makes Benford's parallel career as a scientist and science fiction writer all the more remarkable. In fact, I know of only one "Nobel-Prize class" scientist who also had a major science fiction writing career. Can you guess who? The answer is after the break.

Wednesday, July 22, 2015

The Science of Time Travel

Let me preface this post by saying that I absolutely, positively believe that time travel is impossible.

Having said that, I must now admit that our current laws of physics do not absolutely, positively prove that time travel is impossible, and a variety of eminent scientists over the years have tried to construct models in which time travel is allowed.

Monday, July 20, 2015

Friday, July 17, 2015

Time Travel: A Story

As promised in my previous post, here's a short story of mine about time travel.  It appeared in the December, 2009, issue of Analog.

Wednesday, July 15, 2015

Time Travel: What if You Could Change the Past?

Time travel shares a dubious distinction with faster-than-light travel: they are two of the most popular ideas in all of science fiction, but also two of the most implausible from a scientific point of view. And both of them have become so ingrained in the culture of science fiction that they no longer require detailed justification when introduced into a story. As I noted earlier, the very first time travel novel, The Time Machine, begins with a lengthy explanation of the workings of time travel, while in a modern story Ann and Bob would just jump into their time machine and take off for the 13th century.

Anyone writing about time travel must choose one of two very different possibilities:

1.  Allow the past to be changed
2.  Assume the past is frozen and cannot be altered

This choice produces starkly different types of stories.  Today I want to talk about the first possibility -- I'll save the second for a later post.

Monday, July 13, 2015

Time as the 4th Dimension: a Curious Fact

I'm going to devote my next few blog posts to the ever-popular subject of time travel. In fact, my future self will be writing these posts and emailing them back in time to me, so I won't have to do the actual work of writing them myself.

Before getting started, I wanted to mention a curious fact that most people don't know about (or at least I didn't).

Thursday, July 9, 2015

The Golden Age of Fantasy on Television

When was the Golden Age for fantasy-themed shows on TV? Was it the 1990s, with the debut of The X-Files and Buffy the Vampire Slayer? Or possibly now, with Game of Thrones? Forget about it! There was once a brief time when fantasy shows sprouted on television like weeds in an abandoned shopping-mall parking lot.

Monday, July 6, 2015

Pluto (the Planet, not Mickey's Dog)

With the New Horizons probe reaching Pluto in just a few more days, it seems like a good time to address a couple of questions:

1.  Is Pluto a planet?

I say YES! My opinion has no basis in science -- it arises strictly from a combination of irrational prejudice and childhood nostalgia. And I think if we're going to kick Pluto out of the society of planets, there a few other pieces of debris that should also be expelled, namely Mercury, Venus, Earth, and Mars. After all, the Solar System basically consists of four enormous planets -- Jupiter, Saturn, Uranus, and Neptune -- and a bunch of rocks. My colleague David Weintraub informs me that I won't get very far with a definition of "planet" that excludes the Earth, but I think we should be more open-minded.

2.  What's the best science fiction story about Pluto?

Thursday, July 2, 2015

A Sticky Universe and the Big Rip

Some research I did with Marcelo Disconzi and Tom Kephart at Vanderbilt University on viscosity in the Universe leading to a future "big rip" has recently gotten some publicity.  Here's a story in the New Statesmen.   See, I do occasionally do science.

Update:  article in the Guardian.

Tuesday, June 30, 2015

The Speed of Light in Science Fiction: When Less is More

A science fiction writer can often produce a more interesting story by strictly obeying the known laws of science than by blithely ignoring them.  An obvious example is the speed limit imposed by relativity, which I discussed in an earlier post.  It might seem easier for a writer to just ignore the cosmic speed limit (“jump into hyperspace, Jimmy!”), but one can often construct a more interesting story by adhering to the cosmic speed limit and following where this leads.

The most plausible way to evade the speed of light is to exploit relativity itself, specifically, the time dilation effect.  Time slows down for passengers on a spaceship approaching the speed of light.  So a trip that appears from the outside to take thousands of years might seem to the passengers to take only a few months.  Of course, when they returned back home, the space travelers would find their friends and family turned to dust, making this a not entirely satisfactory means of space travel.  The latter problem figures prominently in the conclusion of Joe Haldeman’s Forever War, in which a soldier on an interstellar combat mission is separated from his girlfriend, and only a few years pass for him, while thousands of years pass back on Earth.  (Haldeman employs a few additional tricks from relativity to ensure a happy ending).  And the ultimate time-dilation tale is Poul Anderson’s Tau Zero.  In Anderson’s novel, a colonization vessel begins to accelerate out of control.  The time dilation becomes so extreme that the crew eventually witnesses (and survives!) the end of the universe itself.

A particularly heartrending exploitation of this idea is "The Old Equations," by Jake Kerr.  (Do you know where the title of the story comes from?)  Before I spoil it for you, you can read the story at Lightspeed magazine.  Kerr's story actually pulls a clever swindle on the reader -- while it adheres slavishly to the laws of relativity, it introduces an idea that is just as implausible (in my mind) as violating the speed of light. But like a good magician, Kerr distracts your attention so that you don't even notice it.

Friday, June 26, 2015

More on the Fermi Paradox

I have a guest blog post on the Fermi paradox here.  This is more science fiction oriented than my earlier discussion -- I examine some of the unusual ideas that science fiction writers have explored (and, in many cases, invented) to explain our lack of alien contact.  Extra credit if you can spot the reference to Veggie Tales.

Thursday, June 18, 2015

Article on Intelligent Life in the Universe

How common is intelligent life in the universe? And if it's common, why haven't we seen it yet? I discuss these questions in an article at The Conversation.

Tuesday, June 16, 2015

Computer Nostalgia: the Birth of the Internet

Yes, like Al Gore, I was there at the birth of the Internet.  OK, maybe not the birth of the Internet, but I was there when the Internet was still in diapers and not playing nicely with other children.

Friday, June 12, 2015

Quantum Immortality

I have to admit that I had never heard of quantum immortality until I read Robert Charles Wilson's short story, "Divided by Infinity." (That's the same Wilson who wrote Spin, which I recommended in a previous post). You can read "Divided by Infinity" online at this site. Take a look at it before I spoil the story for you in the rest of my post.

Friday, June 5, 2015

Quantum Mechanics in Science Fiction

Quantum mechanics is the wacky, spooky carnival funhouse of physics.  Nothing is exactly what it seems to be.  Objects no longer occupy a definite location in space, particles act like waves and waves act like particles, and the act of observing an experiment changes the experimental outcome.  So what happens when science fiction writers try to explore a theory that is so weird that it seems like science fiction itself?

Monday, June 1, 2015

I’ll Give up Fortran when they Pry it from my Cold, Dead Hands

Yes, I still program in Fortran.  And I’m proud of it.  Every so often I tell my colleagues that it’s finally time for me to pick up a new programming language.  Maybe C++.  Or Java.  Lately, Python.  But then I sit down in a quiet place and the urge passes.  You just can’t beat Fortran, and here’s why:

Friday, May 29, 2015

Science Fiction Book and Author Recommendations

A number of you have asked me about my favorite SF novels and writers. Actually, nobody has asked me, but I am going to tell you anyway because it's my blog and I can do anything I want. Hahaha! Such a feeling of power. Napoleon should have written a blog. It would have kept him out of trouble.

Tuesday, May 26, 2015

Looking for Aliens in all the Wrong Places

Scientists have been scanning the radio spectrum for evidence of extraterrestrial life for several decades. But are there other ways that E.T. might try to phone us? Radio is certainly the easiest method to broadcast and receive messages over long distances. But there are much more exotic possibilities,

Friday, May 22, 2015

How I met Wernher von Braun's Bodyguard

During the heyday of the Apollo space program, Wernher von Braun was everywhere -- on the TV coverage of the Apollo missions, in the news magazines -- I even saw him once on a daytime talk show.  He was an all-American hero -- living proof that our German rocket scientists were better than the Russians' German rocket scientists.  Just don't talk about the war...

Wednesday, May 20, 2015

Life on a Neutron Star

Imagine taking a star and squeezing it into a smaller and smaller space.  The pressure inside the star would fight against this crushing force, but eventually it could no longer resist, and the star would collapse into a gigantic atomic nucleus, called a neutron star.  The gravity on a neutron star is a billion times stronger than on the earth – on a neutron star, you’d weigh one hundred million tons.  Or at least you would until you were squished down into nuclear goo. 

Monday, May 18, 2015

Science Quote for the Day

Over the weekend a science kit for my kids mysteriously arrived in the mail. I was asked to "make it work." As a theoretical physicist, I am congenitally incapable of getting any experimental apparatus to perform as it's supposed to, so when I installed the batteries in the battery holder and attached it to the small electric motor, nothing happened. (Yes, I did remember to turn the switch to the "on" position).

Friday, May 15, 2015

Life in the Far Future of the Universe

Could life survive arbitrarily far into the distant future? One hundred trillion years from now, all of the stars will burn out, and the universe will suffer a long, slow decline into darkness. This inevitable decay is predicted by the second law of thermodynamics, which says that entropy always increases.

Entropy is one of those things that everyone talks about, but very few people really understand. Since I don't belong to the latter category, I'll restate the second law in simpler terms:  the second law of thermodynamics is nature's version of the income tax. Whenever you do work, the universe, just like the government, takes a cut.

Wednesday, May 13, 2015

Baseball and Cosmology: a Story

What do baseball and cosmology have in common? Pretty much nothing, except for the short story I'm posting today in honor of the beginning of the baseball season and Yogi Berra's 90th birthday. Baseball does figure prominently in many memorable science fiction stories -- Steven Silver maintains a list of baseball-themed science fiction at his web site. Some of the links are active so you can pull up the stories.

The story I'm posting here, "Extra Innings," appreared in the November, 2004, issue of Analog. Pete Rose gets a brief mention in the story, and Stan Schmidt, the long-time editor at Analog, wrote back to tell me that he had attended high school with Pete Rose in Cincinnati, and they played softball together during gym class! Apparently Rose was much more serious about the softball games than anybody else. (Whenever I tell that story, the first question somebody asks is, "Was Rose betting on the games?").

There are some interesting scientific issues connected to the cosmology in this story, but I don't want to discuss them here because it would ruin the ending of the story.  I'll talk about the science in my next post.

Monday, May 11, 2015

Retro-nostalgia: Yearning for a Future that Never Came

Regardless of whether my previous post was on the mark or not, there's no denying that many of the exciting things promised by classic science fiction never came to pass. We were promised electricity from nuclear power that would be too cheap to meter -- instead, we got phone calls that are too cheap to meter. We were promised household robots to do our cooking and cleaning -- instead, we got robots making cars. (It's arguable that a dishwasher is a type of household robot, but I want one with arms and legs that talks to me while it's doing dishes). And of course, we haven't colonized the solar system, discovered aliens, or built a decent death ray.

Friday, May 8, 2015

The World of the Future: Has it Already Come and Gone?

Science fiction has promised us a glorious future full of lots of shiny gizmos.  But is it possible that technological progress has stalled?

Consider this:

Wednesday, May 6, 2015

Publishers Clearing House Sweepstakes and Mass Extinctions

You may already be a winner!

Actually, probably not.  Your chances of winning the Publishers Clearing House Sweepstakes in a given year are considerably smaller than the probability that a large meteorite will collide with the earth and kill you and everybody else on the planet. Kind of depressing when you think about it.

Sunday, May 3, 2015

Microscopic Humans

In my previous post I looked at giant creatures, but what about the opposite possibility? If insects and reptiles cannot be blown up to monstrous proportions, can people be shrunk to the size of insects? Or even microscopic size?

Friday, May 1, 2015

You Need Not Fear the Giant Ants

Has this ever happened to you?  While you are enjoying a relaxing picnic in the New Mexican desert, your lunch is overrun by ants:  not ordinary ants, but 12-foot-tall behemoths, dripping saliva from their jaws and chittering wildly.  You pull your Browning automatic rifle out from underneath the picnic blanket and empty an entire magazine into the nearest ant, but it doesn’t even flinch.  Instead, it crushes you between its pincers.  Then the ants eat all of your potato salad.

Wednesday, April 29, 2015

Tuesday, April 28, 2015

The Simulation Hypothesis: a Story

Here's the short story, "Copernican Principle," that I wrote after encountering Nick Bostrom's treatment of the simulation hypothesis. It appeared in the March, 2005, issue of Analog.The title comes from my own interpretation of Bostrom's argument -- I think of it as a version of the Copernican Principle, since it relies on the idea that we do not occupy a special place in the universe. And you'll see in the story how that idea gets taken to its logical conclusion...

Monday, April 27, 2015

The Simulation Hypothesis

Are we actually living in a computer simulation? I'm not. But you might be. This idea was explored most famously in the films The Matrix and The Thirteenth Floor. (I actually thought the second of these was a better treatment of the topic). But surprisingly, philosophers and scientists have also taken this idea seriously.

Saturday, April 25, 2015

Do Most Scientists Like to Read Science Fiction?

Folklore has it that many scientists got started on their scientific careers through a childhood interest in science fiction. I am not sure how accurate this is -- in my case, the reverse is true. I began reading science fiction because of a childhood interest in science.

But are most scientists also fans of science fiction? My experience from talking to my colleagues in physics and astronomy over the years suggests that they divide into three roughly-equal groups (this is admittedly an unscientific poll of scientists!) About one-third of my colleagues seem to be avid science fiction fans. This is certainly higher than in the general population, but far from an overwhelming majority. About one-third have never been interested in science fiction. And what of the remaining third? They were science fiction fans as children or teenagers but lost interest as they grew to adulthood. As the famous saying goes, the Golden Age of science fiction is 12.

Thursday, April 23, 2015

Robert Heinlein and the Generation Ship

Among the American Golden Age science fiction writers, the most golden of all was Robert Heinlein. So how did Heinlein go about evading Einstein's cosmic speed limit?  He didn't. And that led to one of the most influential stories in all of science fiction.

Dark Energy

I have an article about dark energy over at The Conversation website. I'll be discussing cosmology in science fiction sometime in the future.

Wednesday, April 22, 2015

Computer Nostalgia

My kids still can't believe that when I went to college (late 70s - early 80s), the campus was served by The Computer, and when The Computer crashed (which it did with alarming frequency), everyone was out of luck.

I had a roommate who worked at the computer center, so naturally he had access to all of the users' passwords. (Hey, it was a more innocent time.  Besides, what could you do if you had access to someone else's password?  Steal all of their Fortran programs?) My roommate told us one night that all of the users thought they were so clever in choosing obscure passwords, but one single password accounted for nearly half the users on the system. Can you guess this password? (Hint: Most computer users back then were also SF fans).

Tuesday, April 21, 2015

Wormholes: a Galactic Subway System

Suppose that you could step out of your front door -- and right onto the surface of Mars. That would be possible with a wormhole -- a shortcut through space. But what would a galactic society linked together by wormholes look like?

Monday, April 20, 2015

Nobel Prize Trivia

Here's a trivia question related to faster-than-light travel:  which winner of the Nobel Prize in Physics appeared (as a character) in a 1960s TV Western?

Friday, April 17, 2015

Warp Factor What?

Faced with the impossibility of travelling faster than the speed of light, what's a science fiction writer to do? The easiest solution is to ignore the problem entirely.  The world of science fiction is full of "warp drives," "hyperdrives," travel through "subspace," and their relatives -- the writer simply assumes that someone, sometime, will figure out a way to circumvent the cosmic speed limit.

Thursday, April 16, 2015

Science Fiction and the Cosmic Speed Limit

One of the enduring themes of science fiction is the galactic empire:  thousands of star systems tied together by gleaming spaceships hurtling through the cosmos.  And why not?  Civilization on Earth progressed from hunter-gatherers eking out a bare existence to planet-spanning empires over the course of a few thousand years.  Surely our next step will be to colonize the Galaxy.  Unfortunately, a galactic empire of this sort would be doomed, not by alien adversaries, nor by internal dissension, but by the discoveries of a German physicist more than a century ago.  Albert Einstein may have been one of the greatest physicists of all time, but he did more to crush the childhood dreams of aspiring interstellar explorers than anyone who ever lived.  Einstein posted a cosmic speed limit back in 1905, and it’s still in force.

Wednesday, April 15, 2015

Cosmic Yarns: Science and Science Fiction

Does the world really need another physics blog? Probably not. Or at least not from me. I want to try something a bit different here. I work as a cosmologist, mainly in the areas of dark matter and dark energy. But I also write science fiction sporadically, and I have always been intrigued by the interplay between science and science fiction -- that's what I want to explore in this blog. Of course, I will also reserve the right to pontificate on extraneous topics that I know nothing about.

You can read some of my science fiction here or here or listen to a podcast of one of my stories here. If you would like to read my scientific papers, I suggest you start with this one.