Toys and dark matter on the web

Subatomic particle plush toys!




Wow. Really. There is even a dark matter particle. Note that the artist has not invested any prestige in preferring a particular hypothesis of the nature of this particle. Is it a neutralino?

Over at Cosmic Variance science blogger John Conway reports from the dark matter conference last week, and gives some more detail on the "nothing detected"result from CDMS I wrote about some days ago. John writes:

To “measure nothing” is usually a great experimental challenge. You do have to convince the world that you would have seen something if it had been there, that your apparatus isn’t just mute for some other reason.

Go read the rest! And see the graph displayed in his post, that shows the limit.

And when I'm at it, I can also link to the Bad Astronomer article, also about the CDMS result and about dark matter in general. Very accessible for a general reader.

"It's just a story"

"It's propaganda", someone is complaining. "Come on, it's just a story, it's fiction!" is the reply.

I'm as guilty as anyone, I have done this many times. Still, it's a lame way to defend a story.

Also, I don't think there is such a thing as "just a story". I think stories are how we understand the world. Fiction is storytelling, giving the reader a picture of how the author is thinking about the world -- and that is very true also for science fiction and fantasy. You get inside someone else's head, get someone else's interpretation of what words and actions and phenomena really mean.

This might be dangerous, or comforting, or just confusing. I also think it's very healthy.

The risk in reading fiction by an author with a worldview different from your own is the same as the risk involved in meeting the author in person. We all have different ways of seeing the world. We have to live together in it, and therefore it's good to know how other people are thinking about things. The stories that many people tell together and agree on will spawn ideologies or policies or projects, and the ones very few like end up on the periphery.

In this way we are making sense of things, building meaning from experiences. This is the essence of storytelling, I think.

Of course, there are people (and books) we don't like, and those we cannot stand because it's almost impossible to find some common ground to start a conversation of any kind. It's annoying, it's frustrating, it can be completely maddening. It can also be like a riddle, an intricate puzzle to solve.

I find it very interesting to try to understand what people like in books, when they see something I don't. It really says a lot about them, and about me, especially when we don't agree.

And still: I refuse to finish a book I cannot find interesting, and I will not read a book just because "everyone" likes it. If it's badly written or full of stereotypes and clichés it will take some really strong ideas to make me finish it. I'm sorry, it's not about agreeing or disagreeing with the message, it's about enjoying the actual reading.

---

This is a response to reading bad customer reviews on Amazon. (One day, the internet is going to make me a misanthrope.) By coincidence, Mike Brotherton also had related thoughts.

Dark matter links

The Sydney Observatory blog is posting Dark matter dialogues, answers to questions from a science fiction author, of all things.

Also, the dark matter thing people are talking about on the net is a survey of large dark matter structure in the universe. (With a cool picture, looking exactly like all other large structure surveys and simulations. But future blue on black.)

Still nothing detected

A few days ago i heard one professor enthusiastically talk about the new results from his group, one of many searching for dark matter. Another professor (I don't know him or what field he is working in) asked him why anyone would be interested in yet another experiment reporting that they have seen no dark matter. Good question. It's really a strange thing, to work year after year with many different methods, and be happy with zero results.

Of course, as people are quick to point out, a zero result is still a result. You know something more about the thing you are hunting for, you can rule out theoretical models and narrow down the search. This is of course why the results are reported and why they are closely watched by the theorists as well as experimentalists.

As I have stated before, it is actually the challenge of searching for nearly undetectable things that attracted me to particle physics, then neutrino detection, and then to dark matter searches. There are all sorts of marvelous efforts going on, to think of ways to detect a dark matter particle (we usually talk about WIMPs, for Weakly Interacting Massive Particles) and distinguish it from other particles that are more prone to interact with matter and give signals in a detector.

One thing that is exploited in dark matter searches is the fact that most forms of radiation (i.e. matter particles or photons) interact with the electrons in matter and don't do much to the atomic nuclei. Atoms are like fluffy clouds of electrons, with a tiny nucleus hiding inside (you might remember the Rutherford experiment). It is way more likely for anything that can interact which the electric fields in an atom to encounter one or more electrons, and perhaps knock them out of the atom, than to slam into the nucleus.

A WIMP ignores the electrons. It is blind to the electric field since it has no electric charge of its own, and it's extremely near-sighted. The weak interaction has a short range, so the probability that the WIMP will actually notice and interact with a nucleus is low -- but it is not zero. If it interacts, it will give some of it's energy to the nucleus, which will recoil.

When a recoiling nucleus moves through the matter in the detector it will also knock off electrons from the atoms it passes through, but since it is heavy and typically carries a lot of electric charge it will do it more efficiently than other particles. If you can build a detector that can identify this pattern and separate it from other interactions, you will already have reduced most of the things that can obscure the visibility of the very rare events where a WIMP actually interacts. This is the basic idea behind many of the efforts to actually find WIMPs.

One example is the CDMS detector. The idea behind this is to use two types of signals. They look at the total ionization, which is the number of electrons knocked out from their atoms. They also look at vibrations that occur when a particle is removed from its place in a crystal lattice. (These vibrations are called phonons, since they can be thought of -- and mathematically treated -- as "sound particles".) By comparing the amount of electrons with the total phonon energy they can identify recoiling nuclei.

It gets a little more complicated, since there are other things that can make a nucleus recoil, for example neutrons. Neutrons, like other kinds of radiation, can come from natural radioactivity and can also be created when cosmic rays interact with matter. In an experiment like this you have to be very careful with the neutrons. Neutrons are absorbed in materials which contains very light elements, like water or plastic that contains lots of hydrogen, so these can be used for shielding. It also helps to put the detectors deep underground, where you are safe from most of the cosmic rays. You also have to take extreme care not to get radioactive elements inside the detector. Interesting challenges. But we are getting very good at it.

The CDMS collaboration has a preprint out (it's one of the first links on that web page if you want to read the actual paper) with a limit that was first presented at a conference last week. A limit, which means that they with a high degree of confidence can say that the WIMP cannot interact better than so much, or else they would have been able to see it. Little by little, we narrow down the possible properties of a dark matter particle.

----

When I'm talking about CDMS I just have to say that their educational pages have a very high level and don't seem to be very accessible for people without physics background. Consider this sentence: "The CDMS experiments (and many others) aim to measure the recoil energy imparted to detector nuclei through neutralino-nucleon collisions by employing sensitive phonon detection equipment coupled to arrays of cryogenic germanium and silicon crystals." Or just the general heavy prose of this one: "The supersymmetric standard model (SUSY) offers a promising framework for expectations of particle species which could satisfy the observed properties of dark matter." That is clearly not the kind of language that works for outreach -- too many difficult words.

As an indication: the reading level of their direct detection page where I took those quotes is "Genius" (while that of this blog is "High school", or at least was before I quoted those things).

Now please tell me if what I have written in this post makes sense!

Interview with Mike Brotherton

Update: added a final question with answer at the end.

This is the first in what I hope will be a series of interviews with interesting people about the relationship between science and science fiction. It will be fun to see various angles on it. Of course I do this mostly out of my own interest: I want to know what thoughts and experiences others have on this subject. At the same time, I hope that this will be of broader interest, and that my readers will appreciate it. Share and enjoy.

First out is Mike Brotherton, "Hard SF Writer" as he states on his blog. Mike is also an astronomer and a professor at the University of Wyoming.

Now: questions and answers!

Someone asked me if reading science fiction has influenced my choice of career. I'm not sure, actually. What about you, what are your thoughts about the relationship between your interest in science and science fiction?

I can't ever remember not liking science and anything that involved science, including science fiction. Discovering how things worked, the mysteries beyond the everyday, were always interlinked in my mind. When I was six, I wanted to be an astronomer or a paleontologist; that was the same age I first saw Star Trek. Furthermore, good scientific research requires imagination, which science fiction has in great abundance. Good science fiction, in my opinion, requires strong grounding in science.

What do you think: does science fiction have any effect on the
public understanding of science, or is it only people of a scientific mindset who read sf anyway?


Science fiction has a tremendous impact on the general public in movies and TV. The written form is more generally reaching the folks scientifically inclined, true, but it's important to realize that science fiction fans fill all sorts of technical roles in our society from scientists to computer support to engineering and more. These are the people who are in positions to make a lot of decisions about how technology is used and what demand there is for it, the movers and shakers if you will in our modern civilization. And without their support, and at least the positive appreciation of the more general public, support for science would wane and research dollars
would dwindle.

Science fiction can be more dangerous, in my opinion, than people appreciate. A steady diet of movies like Jurassic Park that consistently show scientists as arrogant and blithely releasing
dangers into our world does erode public support.

You teach a course on science and science fiction. What have you
learned from that? Any interesting experiences to share?

Teaching this class really helps me sharpen my critical eye about how to communicate science effectively, appreciating the rare times it's well done, and being frustrated at how often it isn't. I marvel at the ingenuity of some of my students, the love-inspired effort they sometimes apply. On the other end of the spectrum, I also realize just how many years I've put into learning the science and the writing both to do it as well as I do (which isn't badly, but I have
plenty of room for improvement).

One of the things I do in my class is have us watch the old classic DESTINATION MOON, a movie from the 1950s about a rocket that goes to the moon. Written by Robert Heinlein, the story was designed to educate the public about how very possible this feat was and to inspire support. It gets a lot of science right, and has a great scene with Woody Woodpecker explaining how rockets work, something that wasn't general knowledge to the extent it is today. I asked my students to write a scene doing the same thing, and got some nice relationships to more familiar experiences like released balloons and jetting squids. The more abstract the concept, the more important it
is to find comparisons to every day life, even if it seems impossible at first.

What do you think about the portrayal of scientists in sf. Do you recognize yourself?

There are some good and accurate portrayals. Ellie Arroway in CONTACT comes to mind. There are more and better examples in books; Gregory Benford's TIMESCAPE is a good one. I can see myself in those characters.

More often, they're nerdy guys in white lab coats and some kind of ridiculous stereotype (Dan Akroyd in MY STEPMOTHER IS AN ALIEN), or nearly the opposite, with Daryl Hanna's ROXANNE or Val Kilmer's super cool dude in REAL GENIUS. Beautiful people played as if the science is a secondary part of who they are, when the reality is nearly every scientist I know lives for science and loves it. We're so talented to get where we are, we could make a lot more money in a different
field, if we cared to. We don't, usually.

What about the portrayal of sf among scientists? Do you ever get
strange reactions if you tell people at work that you are going to a science fiction convention?


My department and campus at the University of Wyoming is generally supportive of my efforts, and I try hard to bring up the positive synergies between science and science fiction. I've gotten NASA and the National Science Foundation to fund some of my science-fiction-related outreach efforts (e.g., the Launch Pad astronomy workshop for writers, see www.launchpadworkshop.org). Bringing in grant money and bringing in high-profile visitors gets positive notice.

And just the same way I have some cachet at science fiction conventions for being the guy who also does real science, a lot of scientists are science fiction fans and they think it's cool that I write novels. Some of my biggest fans are scientific colleagues. The negative folks, the few there are, would actually have to read my books to be too critical and that's usually too much effort. When I travel to give science talks, I'm often asked to also give science fiction talks. The latter typically pull bigger audiences.

Writing takes a lot of time and effort. How do you balance it with work and the rest of your life? Do you have any special writing habits, or designated writing times?


The answer is that the balance is often imbalanced, where I emphasis one or the other for extended periods. The astronomy thing always gets some effort, but I do go months without writing seriously.

Once I start writing on a novel, I write 2-4 hours per day, 1000 words a day, nearly every day, and keep up the momentum through the completion of a first draft.

***

Again, If you want to know more about Mike Brotherton, here's his blog.

Ah, Antarctica...

Yesterday was a day that reminded me of Antarctica. Cosmic Variance had a guest post about IceCube (the kilometer-cubed neutrino detector!) and about working in Antarctica. Almost simultaneously, Mike Brotherton linked to an article about doing astronomy in the whitest place on Earth.

If I'm going to dance my PhD thesis I'll just have to include penguins! (Yes, I did my PhD on AMANDA, which is now a sub-detector in IceCube.)

The winter here in Ontario is white, too. But not very cold, at least not here in the south. (Everyone warned me that the winter was going to be colder than I'm used to. Ha! I haven't even used my warmest clothes. We have had three cold days so far -- and by cold I mean minus 20 during daytime.)

The physicality of dancing

This is wonderful! Can scientists dance? asks the "gonzo scientist" column in Science (it might be that you need a subscription to see it). Videos of scientists interpreting their PhD thesis in dance. I really liked the tango version of a galaxy captured by a larger galaxy. I was actually looking for this article about the COUPP dark matter search, but it's easy to get sidetracked nowadays.

And I suddenly very much miss dancing. I tried tango at a party in December, and some of it actually came back to me after the first stumbling turns. Maybe I should take it up again?