July 2010

Good and Bad Science in Science Fiction

Spent a day last week at the bacchanalia of imagination that is San Diego Comic-Con. Really an amazing experience, anyone who gets a chance should go at some point. My own excuse was appearing on a panel sponsored by Discover and the Science and Entertainment Exchange, on Abusing the Sci of Sci-Fi. I was joined by Jaime Paglia, TV writer and creator of the very charming show Eureka; Kevin Grazier, JPL scientist, blogger, and science advisor to both Eureka and Battlestar Galactica; and Zack Stentz, writer for Fringe and the upcoming Thor movie. We were ably moderated by Phil Plait, and Tricia Mackey provided technical wizardry behind the scenes. We packed the room to bursting, with a long line of people who unfortunately weren’t able to fit inside. There’s a huge demand for this kind of discussion. See also reports here, here, here, here, here.

And yes there is a video record of the whole event! (And other Discover videos.)

The rough idea was to point out examples of good and bad science in science fiction on movies and TV. Phil scored the best example of bad science, finding a brief clip from Armageddon where Bruce Willis is doing delicate work on the surface of an asteroid — in the rain. Jaime and Zack, who actually work in Hollywood, wisely foresaw the pitfalls of holding up someone else’s stuff as an example of badness, and graciously both chose examples from their own work. Sometimes the science must take a backseat to the story.

But not usually. In my own presentation I tried to move beyond the model of scientist as copy-editor, running through stories and films looking for violations of the laws of physics, wagging the finger of shame with ill-concealed glee. I think scientists should take a more creative role, helping fiction writers to develop consistent rules for their fictional worlds and extrapolating the consequences of those worlds, even if those rules are not the rules of our real universe. We should be more than scolds.

Update: since the two clips I showed were apparently missing from the video, I’m linking to them here. The first was a forward-looking philosophy of the proper relationship between science and narrative, and the second was an example of carefully exploring the logical consequences of an imaginary world.

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Guest Post: Eugene Lim on Calculus in Haiti

A little while back we advertised that Eugene Lim had volunteered to visit Haiti to teach in a university there over the summer, and would be reporting back about the experience. Here’s Eugene’s write-up — a powerful and affecting look into conditions there, and the spirit of the students.

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I noticed a puzzled look on Vicky’s face — she was squinting at the blackboard filled with equations describing how the subtitution rule in integral calculus works. She is one of my better students whom I know to be following my lectures well. I took it as a cue that I have not made a point clear, and I knew I must fallen back into speaking as though as my students are native English speakers. They are not — they speak Haitian Creole, and I was trying to teach them basic intro to mathematics in English and and a smattering of Creole.

Hello from Fondwa, Haiti, elevation 850m, Population 8000. For the past twenty days, I have been teaching a group of enthusiastic Haitian university students at the University of Fondwa. As I mentioned in my previous post, the university lost all its buildings during the Jan 12 quake. At the moment, we are using an abandoned warehouse as a temporary campus. It has no roof, so we put a tin roof over to keep the rain out. We use tarps (thank you USAID) for our windows to keep the rain out. There are 3 classrooms and an office. Some of the students have lost their homes in the Jan 12 earthquake, so the university allowed them to stay inside the warehouse.

unifwarehouse

We have no running water and a few solar panels for power. Water is obtained from wells, from a spring (about 15 minutes walk up hill), and from the regular rain showers we have been getting — hurricane season is upon us after all. This often led to me wondering whether I should be wishing for rain so we can fill up our water tank, or for the sun so we can charge up our batteries.

Many of the students are extremely enthusiastic. In my first full day, when I was just waiting for a teaching assignment, Deb, Vicky and Everest approached me and asked me in halting English what I would be teaching. I told them I would probably be teaching them math, and they said they have not had a math professor for the entire semester, and oh would you help us with some of these problems. So I ended up working with them right there and then. Turns out that these vanguard of students have been trying to teach themselves math from some books. They have had some confusion with concepts that one would expect from being self-taught, but they were sharp and intelligent. I found it a joy to work with them. Deb in particular, is especially strong and spoke some English, so I hired him as my Teaching Assistant who can also translate for me. Given his mathematical acumen, I started teaching him more advanced topics in a special class.

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I was assigned to teach two classes in four weeks — an Intro to mathematics (for first years) and the vaguely titled “Business Mathematics” class to the 4th years. After a quick evaluation of the students’ ability, I ended up deciding that I am going to teach the first years differential and integral calculus — useful things to know whether you are going to be an agronomist or a manager. For the “business math” class, I chose to teach them some basic statistics — with the goal that they should be able to deal with frequency and probability distribution functions when completed.

English is not a widely spoken language in Haiti, so it was a challenge to teach the classes. However, I find that we can make a lot of headway with a mixture of my rudimentary Creole and the combined English knowledge of my students, assisted by a dictionary. The classes understandably proceed slower than usual, but that is not always a bad thing in pedagogy. After a hesitant start, we settled on a good system where some of the more capable English speakers would translate for the other students in real time. Sometimes, some of the more advanced students would volunteer to teach a difficult concept which they have grasped to the class in Creole. The students are generally attentive, and eager — I am often asked to teach extra classes.

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When classes are not in session, I am kept busy with students who wanted to learn more, or have questions about math or English. I find these impromptu discussion sessions the most rewarding — I can teach the students at the pace at which they are learning. As a personal bonus, I have the luxury of having the students teach *me* Creole. Although I am assigned a very good Creole teacher, I learned most of my Creole from such constant interaction with the students.

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Living conditions in Fondwa are rough. I am staying in a semi-collapsed building with a couple of volunteers from the US (Rohan Mahy and Reuben Grandon), and a rotating roster of Haitian teachers, most who live outside Fondwa : unfortunately qualified teachers and lecturers are extremely scarce in Haiti. Our quake damaged building has no running water, no power, and red “X” marks on parts of the buildings that are unstable — a non-trivial indicator since we are still experiencing aftershocks (I personally felt three so far). On the other hand, we have a great view — on a clear day, we can see distant Leogane northward and the Gulf of Mexico, 80 km away.

Nevertheless, our humble abode is a palace compared to the conditions that most Haitians live in. Many of them have lost homes in the quake; some of hem are still living in tents. Ironically, many of the stone buildings collapsed, while the wooden ones survived. I visited one of the tent cities of Port-au-Prince — they are hot, dusty, crowded and so incredibly unsanitary that they seems like epidemic timebombs waiting to go off. Every single building left standing suffered some form of damage from the quake — sometimes looking past the intact facade will reveal a completely collapsed back portion of the house. This does not stop Haitians from living in them. There is a strong sense of communal spirit among rural Haitians, more than once, I was told by the tenants that their house was “kraze” (destroyed) in the gudu-gudu (quake) and they are living in that “kind madame’s” house. Our neighbouring house, a wooden structure no bigger than the size of a school bus, is home to thirty men, women and children.

The Haitians are very friendly. After getting past the initial bemusement (and amusement) of being called “blan” (white man) in the first few days, I find the Haitians incredibly hospitable, and resilient in the face of such hardship. Wherever I go, it is easy to smile and call out a “bonjou” or “bonswa”, or “komen ou ye” (how are you?) to people passing me or just doing chores in front of their houses. I have a special love for the Haitian children — they are the most energetic and playful bunch of kids I have ever met. A group of them would show up at our house from time to time, screaming the names of us *blan* volunteers, and we would end up playing with them until we are exhausted. It is poignant for me to know that some of them have lost siblings and parents in the quake.

I will be leaving Haiti in a few days. Personally, I found the teaching experience and my interactions with the Haitians incredibly fulfilling and rewarding. But it was also very sobering to see the damage, destruction and human misery caused by the quake. There is a lingering sense of not having done enough, and that there is so much more left to be done. I do plan to come back again, and perhaps learn enough Creole to teach in it next time.

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How Finely-Tuned is the Universe?

Breaking radio silence here to report on some of the actual work I’ve been able to complete: a new paper with Heywood Tam.

Unitary Evolution and Cosmological Fine-Tuning
Authors: Sean M. Carroll, Heywood Tam
(Submitted on 8 Jul 2010)

Abstract: Inflationary cosmology attempts to provide a natural explanation for the flatness and homogeneity of the observable universe. In the context of reversible (unitary) evolution, this goal is difficult to satisfy, as Liouville’s theorem implies that no dynamical process can evolve a large number of initial states into a small number of final states. We use the invariant measure on solutions to Einstein’s equation to quantify the problems of cosmological fine-tuning. The most natural interpretation of the measure is the flatness problem does not exist; almost all Robertson-Walker cosmologies are spatially flat. The homogeneity of the early universe, however, does represent a substantial fine-tuning; the horizon problem is real. When perturbations are taken into account, inflation only occurs in a negligibly small fraction of cosmological histories, less than 10-6.6×10^7. We argue that while inflation does not affect the number of initial conditions that evolve into a late universe like our own, it nevertheless provides an appealing target for true theories of initial conditions, by allowing for small patches of space with sub-Planckian curvature to grow into reasonable universes.

In English: our universe looks very unusual. You might think we have nothing to compare it to, but that’s not quite right; given the particles that make up the universe (or the quantum degrees of freedom, to be technical about it), we can compare their actual configuration to all the possible configurations they could have been in. The answer is, our observed universe is highly non-generic, and in the past it was even more non-generic, or “finely tuned.” One way of describing this state of affairs is to say that the early universe had a very low entropy. We don’t know why; that’s an important puzzle, worth writing books about.

Part of the motivation of this paper was to put some quantitative meat on some ideas I discussed in my book. The basic argument is an old one, going back to Roger Penrose in the late 1970’s. The advent of inflation in the early 1980’s seemed to change things — it showed how to get a universe just like ours starting from a tiny region of space dominated by “false vacuum energy.” But a more careful analysis shows that inflation doesn’t really change the underlying problem — sure, you can get our universe if you start in the right state, but that state is even more finely-tuned than the conventional Big Bang beginning.

We revisit this question, bringing to bear some mathematical heavy machinery developed in the 1980’s by Gary Gibbons, Stephen Hawking, and John Stewart. Previous discussions have invoked general ideas of entropy or reversibility, but we were able to do a relatively down-to-earth calculation using conventional cosmological models. And we tried our best to explicitly list all of the caveats of the argument, which is important in a context like this where we don’t know all the rules.

We find that inflation is very unlikely, in the sense that a negligibly small fraction of possible universes experience a period of inflation. On the other hand, our universe is unlikely, by exactly the same criterion. So the observable universe didn’t “just happen”; it is either picked out by some general principle, perhaps something to do with the wave function of the universe, or it’s generated dynamically by some process within a larger multiverse. And inflation might end up playing a crucial role in the story. We don’t know yet, but it’s important to lay out the options to help us find our way.

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