Children of light and children of darkness is the vision of physics that emerges from this chapter, as from other branches of physics. The children of light are the differential equations that predict the future from the present. The children of darkness are the factors that fix these initial conditions.
— Misner, Thorne, and Wheeler, Gravitation (1973), p. 555.
This was originally relegated to a tweet, but it deserves to be elevated to a blog post. Bobby McFerrin, at the World Science Festival, demonstrating the pentatonic scale. A rare combination of joy, passion, and teaching. I dare you not to smile at the 0:42 mark.
World Science Festival 2009: Bobby McFerrin Demonstrates the Power of the Pentatonic Scale from World Science Festival on Vimeo.
Not all scientists work at universities. (Maybe not even most? I honestly don’t know the breakdown.) But people who do work at colleges and universities sometimes talk as if that’s all there is, or that becoming a professor is the only logical goal for those pursuing a scientific degree — not necessarily from snootiness or elitism, but just because that’s what they know.
So it’s great that Chad Orzel has done a series of short interviews with scientists outside academia, and is gradually blogging the results. It’s a nice little bit of informal sociology of the field, and a useful resource for anyone who might be contemplating such a career path themselves.
Chad, as you probably know, has also written a book that will be coming out later this year. And he’s supposed to be doing scientific research, and keeps up an active blog! How is that possible?
Last week, members of the Caltech community received a dreaded piece of email: a student had taken their own life. The tragedy was compounded by the fact that this was the third Caltech student to do so in the last year.
Suicide is the second-leading cause of death among college students. In the aftermath of such an event, there is a feeling of powerlessness; you try to console or sympathize with anyone who might have known the student, but at the end of the day there’s no much you can do. But it is possible to take some steps to try to prevent such tragedies from happening.
It is believed that, in over 80 percent of cases, people who attempt suicide are struggling with some form of mental illness, such as depression, bipolar disorder, or schizophrenia. Although there is no way to know for sure whether someone is contemplating such a drastic step, there are certain warning signs, including severe depression and changes in mood or habits. Caltech has set up a website on preventing suicide and violence, which goes over some of the signs and ways that a friend can take steps to help persuade someone from going too far:
I’m sure that many universities (and companies) have similar resources; it’s worth taking a minute to familiarize yourself with what’s available where you work or go to school.
Most importantly, if you’ve ever contemplated suicide yourself: don’t do it. That’s cheap and easy advice, but the crucial point is to make sure you stop, talk to people, and take advantage of counselors. Being a college student can be an extraordinarily stressful and pressure-filled time; if you’re feeling overwhelmed, be assured that it’s not just you, and that it is possible to get through it. You will find people who are willing to listen, understand, and try to be helpful, if you are willing to reach out to them. Tough times can be overcome, but taking a life is irrevocable. Seek help before the pressure gets to be too much.
Here at Cosmic Variance we love our teaching moments. Science is everywhere, and there’s no need to be stuffy about it. One of the best ways to communicate the excitement that we feel about science to a much wider audience is to connect it to popular culture in all sorts of ways — whether it’s Buffy the Vampire Slayer, NUMB3RS, or Angels & Demons.
So it’s great to see the producers of ABC’s hit TV show LOST jump on the bandwagon. This fall they will be releasing the DVD collection of the fifth season, and the Blu-ray edition is going to feature a special treat: mini-“lessons” on various academic subjects related to the show. (The final season of the show begins early in 2010.) One of those subjects is time travel, and you have a pretty esteemed group of professors guiding you through this fascinating subject: Nick Warner of USC (who taught me general relativity back in the day), our old friend Clifford Johnson, and myself. Suffice it to say, I’ve seen the rough cut, and they did a good job — and we had quite a bit of fun. I was only included because having all the professors speak with British accents would have seemed a bit posh.
And along with that, they’ve just launched an associated website: LOST University. You can see what the other courses in the curriculum are going to be, including Philosophy and Foreign Languages. At the moment the website is essentially promotion for the DVD’s themselves, but I’m hoping more content will appear over time. LOST has a tradition of enhancing the show with quite elaborate online activities, in the form of alternate reality games. So hopefully this new site won’t simply be an advertisement — one of the lessons of new media is that giving away cool stuff for free makes it more likely that people will pay money for the even cooler stuff.
To be clear: the science of time travel on LOST does not necessarily obey all the rules. None of us had anything to do with the show itself, and I have no idea what the writers did in terms of seeking science advice. But understanding how the rules are broken can serve as fodder for teaching moments just as easily as seeing them obeyed. That’s life here “on the cutting edge of tomorrow.”
Everyone and their niece is emailing me that I should post these. (And Aatish in comments.) And a good thing, too, because it usually takes at least half a dozen emails before I will do anything at all.
In 1964, Richard Feynman gave the Messenger Lectures at Cornell, aimed at a general audience. They were later collected into The Character of Physical Law, a great little book with a depressingly boring cover. Feynman-worship is often overdone, but man, the guy could lecture. And he knew a lot about physics!
The good news is that Bill Gates has now put the full video of the lectures online, as part of Project Tuva. I had to update some software to view them on my Mac, but it seems to be working now.
Lecture Five is about the arrow of time. If you skip ahead to the 18th minute or so, you’ll hear Feynman explain the Boltzmann Brain argument.
One frustrating aspect of our discussion about the compatibility of science and religion was the amount of effort expended arguing about definitions, rather than substance. When I use words like “God” or “religion,” I try to use them in senses that are consistent with how they have been understood (at least in the Western world) through history, by the large majority of contemporary believers, and according to definitions as you would encounter them in a dictionary. It seems clear to me that, by those standards, religious belief typically involves various claims about things that happen in the world — for example, the virgin birth or ultimate resurrection of Jesus. Those claims can be judged by science, and are found wanting.
Some people would prefer to define “religion” so that religious beliefs entail nothing whatsoever about what happens in the world. And that’s fine; definitions are not correct or incorrect, they are simply useful or useless, where usefulness is judged by the clarity of one’s attempts at communication. Personally, I think using “religion” in that way is not very clear. Most Christians would disagree with the claim that Jesus came about because Joseph and Mary had sex and his sperm fertilized her ovum and things proceeded conventionally from there, or that Jesus didn’t really rise from the dead, or that God did not create the universe. The Congregation for the Causes of Saints, whose job it is to judge whether a candidate for canonization has really performed the required number of miracles and so forth, would probably not agree that miracles don’t occur. Francis Collins, recently nominated to direct the NIH, argues that some sort of God hypothesis helps explain the values of the fundamental constants of nature, just like a good Grand Unified Theory would. These views are by no means outliers, even without delving into the more extreme varieties of Biblical literalism.
Furthermore, if a religious person really did believe that nothing ever happened in the world that couldn’t be perfectly well explained by ordinary non-religious means, I would think they would expend their argument-energy engaging with the many millions of people who believe that the virgin birth and the resurrection and the promise of an eternal afterlife and the efficacy of intercessory prayer are all actually literally true, rather than with a handful of atheist bloggers with whom they agree about everything that happens in the world. But it’s a free country, and people are welcome to define words as they like, and argue with whom they wish.
But there was also a more interesting and substantive issue lurking below the surface. I focused in that post on the meaning of “religion,” but did allude to the fact that defenders of Non-Overlapping Magisteria often misrepresent “science” as well. And this, I think, is not just a matter of definitions: we can more or less agree on what “science” means, and still disagree on what questions it has the power to answer. So that’s an issue worth examining more carefully: what does science actually have the power to do?
I can think of one popular but very bad strategy for answering this question: first, attempt to distill the essence of “science” down to some punchy motto, and then ask what questions fall under the purview of that motto. At various points throughout history, popular mottos of choice might have been “the Baconian scientific method” or “logical positivism” or “Popperian falsificationism” or “methodological naturalism.” But this tactic always leads to trouble. Science is a messy human endeavor, notoriously hard to boil down to cut-and-dried procedures. A much better strategy, I think, is to consider specific examples, figure out what kinds of questions science can reasonably address, and compare those to the questions in which we’re interested.
Here is my favorite example question. Alpha Centauri A is a G-type star a little over four light years away. Now pick some very particular moment one billion years ago, and zoom in to the precise center of the star. Protons and electrons are colliding with each other all the time. Consider the collision of two electrons nearest to that exact time and that precise point in space. Now let’s ask: was momentum conserved in that collision? Or, to make it slightly more empirical, was the magnitude of the total momentum after the collision within one percent of the magnitude of the total momentum before the collision?
This isn’t supposed to be a trick question; I don’t have any special knowledge or theories about the interior of Alpha Centauri that you don’t have. The scientific answer to this question is: of course, the momentum was conserved. Conservation of momentum is a principle of science that has been tested to very high accuracy by all sorts of experiments, we have every reason to believe it held true in that particular collision, and absolutely no reason to doubt it; therefore, it’s perfectly reasonable to say that momentum was conserved.
A stickler might argue, well, you shouldn’t be so sure. You didn’t observe that particular event, after all, and more importantly there’s no conceivable way that you could collect data at the present time that would answer the question one way or the other. Science is an empirical endeavor, and should remain silent about things for which no empirical adjudication is possible.
For a long time, the government has been responsible for space travel in the United States. That’s about to change.
Government is the appropriate agent for certain forms of collective action: roads, public schools, national defense. It’s also good for big-picture things without immediate financial payoff, like support for the arts or basic scientific research. It makes perfect sense for the government to shoulder the burden for developing the technologies to get us into space, and it will continue to make sense for them to play an active role in astronomical research in space. But for commercial purposes, like launching satellites, it ultimately makes a lot more sense for space travel to be a private-sector enterprise. We’re on the brink of seeing it happen.
SpaceX is a private company founded by Elon Musk, who previously co-founded PayPal and the electric car company Tesla Motors. For a while now, SpaceX has been developing reusable launch vehicles and space capsules. They’ve been awarded a contract from NASA to take over re-supplying the International Space Station after the Shuttle fleet is mothballed next year. And they’ve had one launch that reached orbit, but also a few failures; until yesterday, they hadn’t succeeded in putting a satellite into orbit.
But now they’ve done it. I was watching on live webcam last night as the Falcon 1 rocket launched a Malaysian satellite into orbit.
It’s incredibly exciting, but just the beginning. The idea behind the Shuttle was to make trips to orbit cheap, reliable, and routine; it failed spectacularly on all counts, and NASA’s capabilities and plans for space flight have become somewhat disjointed (while its science missions continue to have amazing success). Hopefully we’re moving past the point where we have to rely on the government to get us to space.
Scientists like to argue, contra Walt Whitman, that understanding something increases our appreciation of its beauty, rather than detracting from it. The image below, as Evalyn Gates explains, is a perfect example. Evalyn is an astronomer at the University of Chicago, and the author of a great new book on the science of gravitational lensing, Einstein’s Telescope: The Hunt for Dark Matter and Dark Energy in the Universe (Amazon, Barnes & Noble, Powell’s). This post is an introduction to how gravitational lensing gives us some of the most visually arresting and scientifically informative images in all of astronomy.
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I had the pleasure of meeting up with Sean and some other old friends at the World Science Festival in NYC last month, and over champagne at the opening night reception (science has its benefits) Sean graciously invited me to write a guest post on gravitational lensing. It’s a broad topic, mainly because lensing is proving to be such an incredibly useful tool for many areas of cosmology and astronomy, but I have to admit that the visual beauty of the images produced by lensing is part of the appeal for me.
I’m also enamored of the visceral connection between these images and lensing phenomena that all of us encounter in daily life – and the access into a complex theory that this connection affords. The giant arcs, Einstein Rings, and multiple copies of a single distant galaxy or quasar that have now been observed in hundreds of images are concrete visualizations of otherwise abstract concepts of general relativity – they effectively trace out the warps in spacetime created by massive objects, revealing the outline of the cosmos much as the technique of “rubbing” can reveal the writing on an ancient gravestone.
This image, from a recent paper by Adi Zitrin and Tom Broadhurst is both scientifically and visually irresistible:
First, the image itself is really cool. The bright white/yellow galaxies are members of a cluster known as MACS J1149.5+2223, while the blue amoeba-like objects that appear to be invading the cluster are actually five images of a single distant (z ~ 1) spiral galaxy.
This galaxy has been lensed by the warp in spacetime created by the cluster. Light from the galaxy, which lies almost directly behind the center of the cluster but much farther away from us, travels along several curved paths through the cluster lens, producing multiple magnified images of the galaxy. The inset box shows a computer generated model of the unlensed source galaxy, enlarged by a factor of four so that the details, including the spiral arm structure, are visible. Without the lensing power of the cluster, we would see this galaxy as a single small blue smudge.
In general, lensing will both magnify and distort (shear) images of a background source. This lens is fairly unique in that we see large but relatively intact images of the spiral galaxy, which implies that the mass distribution in the central region of the cluster must be nearly uniform. The images in the upper left (#1) and lower right (#2) are especially striking. #1 is magnified but very minimally distorted, while #2, the largest image with a magnification of over 80, seems to be curling its tentacles about one of the galaxies in the cluster.
A close look also reveals the negative parity (mirror symmetry) of the remaining three images – the spiral arms appear to circle in the opposite direction – as expected from lensing. The total magnification of the distant galaxy (the sum of all five images) is about 200, the largest known to date – supporting the authors’s claim that this is “the more powerful lens yet discovered.”