The Mystery of Cosmic Lithium

When most people think of lithium, they probably think of antidepressants, or possibly lithium batteries. But to a cosmologist, lithium is the misshapen puzzle piece -- the one that won't quite fit, no matter how hard you push it.

What does lithium mean to you?

Most of the elements were produced in the nuclear furnaces of stars or supernovae, but a handful were made in the first few minutes of the universe, when it was incredibly hot (billions of degrees) and dense. These big bang elements include helium, deuterium (a form of hydrogen with an extra neutron) and one isotope of lithium. Our theory, called "big bang nucleosynthesis," gives beautiful agreement with the observed helium and deuterium abundances, but it fails miserably for lithium -- the theory predicts about three times as much lithium from the big bang as we actually observe.

So what's going on here? As one of my high-school teachers used to say, "half-right equals all wrong." But the fact that big bang nucleosynthesis works so well for helium and deuterium suggests that maybe it just needs a few tweaks, instead of wholesale reworking. Roughly speaking, there are three likely alternatives:

Physics in the Year 2116

Last year Physics Today ran an essay competition called "Physics in 2116." The idea was to write a science article that might appear in Physics Today 100 years from now. Motivated largely by the enormous prize money, I entered the competition but, alas, mine was not among the winning entries. As the article itself is not really suitable as either a science fiction story or a nonfiction article, I am presenting it here for your amusement. Be sure to read the footnotes.

Lies, Damned Lies, and Astronomy Photos

I'm sure you've all see beautiful images like this NASA photo of the Crab Nebula:

Who you gonna believe, me, or your own eyes?

Just imagine if you looked at the Crab Nebula through a powerful telescope -- you'd see something that looked... nothing at all like this. That's because the colors in astronomy photos are almost never the "true" colors that you would see with the naked eye. They're "false color" photographs, with different colors assigned to different wavelengths of light or (in this case) to images derived from different telescopes.

When I first realized that false color photos were the standard in astronomy, I was dismayed. What else had NASA been fibbing about? The Moon landings? But NASA hasn't been lying at all, and there's no reason to get upset about false color photos. And here's the reason why: your own eyes give you a false-color picture of reality.

Germany's Famous Science Museum

I spent last week in Munich -- my first visit to Germany in 30 years. At this point, I am supposed to insert the obligatory paragraph expressing shock and surprise at how much everything had changed. But frankly, Germany didn't seem all that different from the last time I was there. Societies have a lot more cultural inertia than we realize.

My personal high point of the trip was a visit to the famous Deutsches Museum, the top German museum of science and technology.  It's the largest science museum in the world, and a true monument to Teutonic thoroughness: why include just a few slide rules in your computing exhibit, when you can display one of every type of slide rule ever made?

The high level of the exhibits is remarkable, especially compared to U.S. science museums, which have largely been dumbed down to the level of children's museums in the course of my lifetime. The Deutsches Museum tilts heavily toward physics and engineering -- we skipped the exhibits on machine tools and metallurgy.  But I learned quite a few fun things in the course of my visit:

• Despite the fact that the wheel was known in ancient times, the wheelbarrow was not invented in the West until the Middle Ages.
• It's possible to slice a torus (i.e,. a donut) along a Mobius-strip-shaped cut, so that the torus gets cut all of the way through but doesn't fall into two pieces (that's really hard to explain in words, but the museum had a nice model to demonstrate).
• Germans apparently have a much longer attention span than Americans -- all of the push buttons on the exhibits required you to hold them down much longer than would be the case for an American museum. Several times I thought an exhibit was broken, only to discover that I had not depressed the button long enough.

First Conference of the Society of Catholic Scientists

The new Society of Catholic Scientists held its inaugural conference last weekend in Chicago -- you can read all about it at the Forbes website here. I thought the conference was enormously fun. It's a sad fact that most of us in academic science end up funneled into narrower and narrower specializations, until we end up talking almost entirely to other people in our own field. In Chicago I got to meet a Penn paleontologist who digs up dinosaur fossils in Western China, an MIT linguist studying the birth of human speech (who also loves science fiction!), and a Harvard astrochemist examining the possibilities for life on other planets.

My own talk was on Georges Lemaitre, the Catholic priest who pulled together various observational and theoretical threads in the 1920s to develop the the Big Bang model. Modern cosmology had many fathers, but only one Father.

A New Email Low

I've hit a new low -- Vanderbilt's spam filter blocked a message I sent to myself. It says that I might not be the person I claim to be. I guess that's true.

Galileo and Dark Matter

I was drafted recently to give a talk about Galileo, a subject on which I am no expert. So I relied heavily on Rocky Kolb's book, Blind Watchers of the Sky (I wrote my very first physics paper with Rocky back in 1981, back when we were both, uh, about 12 years old), and on Michael Flynn's brilliant, if somewhat irreverent (coming from me, the latter is higher praise than the former), The Great Ptolemaic Smackdown.

When doing scientific research, you quickly come to realize that progress in science consists of thousands of blind alleys (for you), punctuated by the occasional breakthrough (for someone else). In the textbooks, all of the blind alleys get airbrushed away (who has time to study incorrect theories?), leading to the erroneous impression that science has been been one long march to the Truth. But it never happens that way.

For example, one of Galileo's main arguments for the Copernican model was his theory of the tides. He noticed that as the Earth moves around the Sun, the surface is moving faster at midnight than at noon, since in the former case the motion around the sun is in the same direction as the rotation of the Earth, and vice-versa at midnight.

So Galileo claimed that the water would bunch up at noon and spread out at midnight, leading to a low tide at midnight and high tide at noon (or maybe the other way around?)  A couple of problems here:  there are two high tides and two low tides a day, not one, and they occur at different times of the day, not just noon and midnight.  Galileo's theory was completely wrong, which is why you've never heard of it (except for you, Michael...)  But (and this is the weird part), I drew a diagram exactly like this one for my cosmology class a few weeks ago. Why?

Science Fiction Set In Your Home Town

If you grew up in New York or Los Angeles, you'll find no dearth of science fiction set in your home town, with familiar locales and landmarks. The same thing applies if you were born in Trantor, Diaspar, or Coruscant. But if, like me, you come from the Midwest, you won't see a lot of local color in the science fiction you read.

I grew up in St. Louis, so I was delighted to encounter The Jericho Iteration, by Allen Steele. Steele's novel is a science fiction conspiracy thriller set in a St. Louis devastated by an earthquake on the New Madrid fault. I enjoyed recognizing the numerous local landmarks in the novel, although I didn't actually like the story itself. But that's beside the point -- the important thing is that St. Louis has a science fiction novel to call its own.

I should also mention that the near-future dystopian film Escape from New York was filmed in St. Louis, despite being set in New York. Apparently New York was insufficiently run down to serve the filmmakers, so they came to St. Louis instead. Now that's something for a native St. Louisan like me to be proud of.

What about my adopted home of Nashville?

Texas Talk on Science and Science Fiction

I'm giving the physics colloquium at Texas A&M tomorrow (Thursday, Mar. 9) on science and science fiction. Details are here.

What if Robert E. Lee had Tactical Nuclear Weapons at Gettsyburg?

The Confederacy would have won the battle, but the battlefield park probably wouldn't be such a nice place to visit these days.

The genre of "alternate history" explores fictional paths that history might have taken. Is it a branch of science fiction? I have no idea. Certainly time-travel alterations to the historical timeline and parallel universes fall squarely under the science fiction heading, but straight alternate history is often placed in a category all its own.

I enjoy alternate history, although it tends to follow just a few well-worn themes:  What if the South had won the Civil War? What if Hitler had won World War II? What if the South had won the Civil War? What if Hitler had won World War II?...  So I was eager to read Harry Turtledove's new novel, Bombs Away, which examines the consequences of Harry Truman deciding to use nuclear weapons to wrap up the Korean War. This historical era (the early Cold War) is one that I find particularly fascinating, and I've enjoyed Turtledove's work in the past -- he's built an impressive career in the field of alternate history.

When a Physicist Needs to Consult an Economist

As a physicist, I never expected to turn to the results of economics to advance my research. And I never have. But the death this past week of Kenneth Arrrow, a Nobel-Prize winning economist, reminded me of one occasion on which I had to invoke Arrow's work in my role as department chair to settle a dispute. Or rather, to show that it could never be settled. Arrow proved some mathematical results concerning elections that are so bizarre and so disturbing that it's difficult to believe them -- and these results are still largely unknown to most people.

Is Technology Taking Us Back to a Victorian Lifestyle?

Imagine making a telephone call in the early 20th century:  you'd just tell the operator the name of the person you wanted to reach, and the operator would connect you. This all changed with the development of automatic switching. It was progress of a sort -- no need to go through a human operator. Instead, you had to memorize a host of phone numbers and dial up (or later, punch in) the number you wanted. But now smart phones have taken us full circle. Just like our forebears, you can simply speak the name of the person you want to talk to (or, at worst, pull up a name on your screen), and the phone does the rest. Telephone numbers (and the need to remember them) are going the way of the buggy whip.

A Most Peculiar Holiday

Almost all physics departments host a weekly colloquium, at which an outside speaker presents a talk on a current research topic -- it's traditional to take the speaker out to dinner afterwards. When I began my first appointment as a junior faculty member (at Ohio State), this task often fell to the single faculty members -- our schedules were more open, and we were grateful for the free meals and the company.

One Tuesday evening, a group of five of us (all guys) took the speaker out to a local restaurant, only to discover that they didn't have a free table. This was a bit odd for a Tuesday night, but we simply went to our second-choice restaurant, only to discover that it was full as well. Finally, one of us realized that it was Valentine's Day! That's right, none of us, including the speaker, had remembered that Feb. 14 was of any significance. (This story has a happy ending -- we found a Chinese restaurant with available seating).

Confessions of a Cowboy Cosmologist

We recently watched The Magnificent Seven (the original, not the remake). It's a good movie, even if Yul Brynner, with his bald head and vaguely Eastern European accent, sometimes gives the impression that he wandered in by mistake from an adjacent movie set.

Which way to The King and I?

There's an odd similarity between the closing of the western frontier and my own research field of cosmology. In the early 1980s cosmology was the crazy no-holds-barred Wild West of science.  Cosmologists knew that the Big Bang theory was correct: the universe started out incredibly hot and dense and then expanded and cooled to form the space we inhabit today. But there was so much that we didn’t know. What was the universe made of?  Would it expand forever, or collapse back down and crush us all into an atomic soup? Where did all of the galaxies come from? We didn’t even know how fast the universe was expanding: the two groups measuring the expansion rate kept getting answers that differed by a factor of two! But life on the lawless frontier was great fun for theoretical physicists like me. With so little data to go on, we were free to speculate endlessly -- no theory was too outlandish to publish. We roamed the scientific landscape like cowboys, drifting from one new idea to the next. And theories sprouted like tumbleweeds, only to blow away when the next hot idea came along.

But then the experimentalists came to town and started fencing us in. First came the astonishing discoveries by astronomers mapping out the expansion of the universe on the largest scales. These investigators used distant supernovae, so far away that the light from these cosmic explosions took billions of years to reach us. These supernovae allowed the scientists to peer back in time and measure the expansion rate of the universe billions of years ago.  And they made a shocking discovery: the expansion of the universe isn’t slowing down under the force of gravity; instead, it’s speeding up! Next came the precision measurements of the radiation left over from the early stages of the Big Bang. This radiation contains tiny ripples that encode information about the universe:  its age, how much matter it contains, and what kind of matter it’s made of.

Life Under a Double Star

You've all seen the iconic image: Luke Skywalker on Tatooine, gazing into the sky at two suns. That's George Lucas's way of whacking us over the head with a two-by-four -- "Toto, I've a feeling we're not in Tunisia anymore."

Could life actually exist on a planet orbiting a binary star? Ivan Shevchenko has recently made an extraordinary claim -- he argues, in this paper, that life is actually more likely to develop around binary stars than around a single star like our Sun. In Shevchenko's view, we are the weird ones, while life on planets like Tatooine should be common.