Galactic Interactions

Internet Astrophysics Celebs Carroll & Gay to Speak in Second Life

Posted on February 4th, 2010 — permalink

For those of you who haven’t been following my blog or watching my twitter or facebook updates, you may not realize that there are regular public-outreach astronomy talks in Second Life. These are designed for the general public, and are open to anybody. Indeed, because a Second Life account is free, they really are open to anybody. These talks are on Saturdays at 10 AM pacific time / 1 PM eastern time, are sponsored by the Meta-Institute of Computational Astrophysics, and are held in MICA Large Amphitheater of the StellaNova region in Second Life.

This series has historically been called “Dr. Knop Talks Astronomy”, because through the end of 2009 I have given the lion’s share of the talks. Indeed, I was thinking about it the other day. The last semester before I left Vanderbilt, I was contacted by the people who make the CD series called “The Great Courses”. These are CDs with lectures from university professors on their topics of expertise. Based on some podcasts of mine that were online from several years ago, they contacted me and asked me to come audition. The idea was that if I passed it, they might well produce a course from me. However, when I left Vanderbilt, and could no longer call myself a “Professor of Physics and Astronomy”, they were no longer interested in me.

It occurs to me that given the number of talks I’ve presented so far, those who have come to most or all of my talks have effective received the equivalent of one of these CD series on “hot topics in astronomy.” Indeed, it was more than that, for not only were there visuals (i.e. my slides), but it was interactive. You could ask questions, and also discuss the talk with the others present.

If you look at our schedule for this coming semester, you’ll see that we’re starting to mix things up some more. I’m still giving more of the talks than any other single person, but we’ve got a larger range of guest speakers. You can see who’s coming up soon by looking at the Upcoming Public Events page.

Last week, we had Nobel Prize winner John Mather speaking about the history of the whole Universe, and of hopes and plans for the upcoming Webb Space Telescope. In the next two weeks, we’ll have two “Internet Celebrities” talking. Sean Carroll, one of the authors of the popular physics blog Cosmic Variance, will be talking about his recently released book on the nature of time, From Eternity to Here. Then, Pamela Gay, host of 365 Days of Astronomy and a member of Astronomy Cast, will be speaking in two weeks.

Drop by and hear us. These talks can be very good… and, while you shouldn’t believe me if I tell you my own talks are good, others have told me that they are. The immersive environment of virtual worlds means that you really feel you are there— John Mather was commenting on this just last week after giving his talk.

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Me in the Infrared

Posted on January 5th, 2010 — permalink

The Spitzer booth at the AAS has an infrared camera set up, so you can see what you look like in wavelengths just longward of one micron.

This is me:

I’ve got my mouth wide open in a jolly smile, which is why that part is glowing. Meanwhile, you can see that my glasses do not transmit infrared light as well as they transmit optical light, and are not as warm as my face, so they show up as dark spots.

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How long does it take planets to form?

Posted on January 5th, 2010 — permalink

One thing that’s currently unknown— and there remain debates among the theorists and modellers— is how long it takes for planets to form. Timescales vary between 1 and 10 million years. What’s more, based on our understanding of the environments around very young stars, big gas giant planets have to form a fair distance away from the star (equivalent to where you find Jupiter and Saturn in our Solar System), yet we’ve found lots of Jupiter-sized planets very close to their star… so, our current understanding is that those planets not only have to form, but have to migrate in.

One thing that would help us figure out the timescale for planet formation is doing searches for planets around very young stars. Below is a poster that reports the discovery of the youngest exoplanet known:

Click for a giant version

Shown is graduate student Chris Crockett of Lowell Observatory. (And, if his advisor is looking at this, no, that’s not a beer!.) (Although, to be perfectly honest, I have to admit that the reason I sought out this particular poster is that the second author is Naved Mahmud, graduate student at Rice who worked with me at Vanderbilt, and who made one of the nicest comments a blogger could ever hope to get, so, see, flattery sometimes does get you somewhere!)

What they’ve discovered is a planet orbiting a Classical T-Tauri star. If you don’t know what that means, you’re like me… or, rather, you’re like me several years ago. However, I was at Vanderbilt for six years, where David Weintraub and his students were doing a lot of work on T-Tauri stars, so as a result I learned something about them. T-Tauri stars are stars like the Sun, only still in the late states of formation. They’re not protostars, really, any more, but they haven’t yet ignited fusion at their cores. They are what’s known as “Pre-Main Sequence” stars. (Yes, folks, that’s what astronomers think PMS means.) There are “Classical” and “Weak” T-Tauri stars, based on the strength of the Hα emission line. Our understanding is that the Hα results from accretion of gas on to the star— and Crockett et al. have more evidence to support this. What does this mean? There is still a substantial gas disk around the star, putting the protoplanetary disk almost certainly within the first million or two years of it’s life.

In other words: what these guys have discovered is a Jupiterish planetary mass condensed around a star that’s at most a couple of million years old. This is an extremely relevant constraint on how long it takes to form planets, and will be big news for those who try to theoretically understand the original formation of our Solar System and other planetary systems.

This work should be submitted to a journal sometime soon, and presumably sometime thereafter it will show up on arxiv.org.

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Result from Kepler : a planet’s light blocked by a star

Posted on January 4th, 2010 — permalink

This morning the invited talk at the AAS meeting was William Bourucki of NASA/Ames talking about first results from the Kepler mission. The coolest thing he described was an object that’s too hot to be a planet, but too big to be the kind of star it could be…! More about that later.

Right now, I want to show my blurry snapshot of his plot of the lightcurve of an already-known exoplanet named HAT-P-7:

This is a plot of the brightness of the star versus time. This was a previously known planet. In the top, you see the Kepler data that results from when the planet transits the star. That is, the planet moves across the face of the star, blocking out a little bit of the starlight, causing the star to get just a wee bit dimmer. The planet is much dimmer than the star, so it only blocks out a bit of the starlight, but Kepler is sensitive enough that this is an extremely strong detection.

What’s cool is when you zoom in on the plot. You see a second dip to the right. What you’re seeing there is the light of the planet being blocked by the star. The planet shows reflected light from the star, which adds to the overall light you see. However, when the planet is occulted by the star, you no longer see that reflected light… and you get a secondary dip.

A number of extrasolar planets have been detected by looking for stars whose light is briefly blocked out due to an orbiting planet moving in front of the star. Kepler is a spacecraft designed to find lots of these planets. It’s really cool that it’s sensitive enough that it’s seeing the light of a planet blocked out by a star…!

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AAS Astronomy Events Live Streamed into Second Life

Posted on January 4th, 2010 — permalink

I’m at the annual big meeting of the American Astronomical Society this week in Washington, DC. Lots of stuff going on, and I’m already overwhelmed by the sheer number of people here. (And, also, depressed by the number of young people here in comparison to the number of entries on this list.

Several of the bigger events— press conferences, invited talks— are going to be live streamed into Second Life. Drop by the Astronomy 2009 island to hear the talks, including the Wednesday at 8AM Eastern / 5AM Pacific talk by astronaut and Hubble Mechanic John Grunsfeld. These events are hosted by Astronomy 2009 and by the Astrosphere New Media (Pamela Gay’s and others’ new venture). A full schedule is here.

Remember that a Second Life account is free! Drop by and check it out. And, once you’ve got a Second Life account, nothing will be stopping you from coming to hear my public astronomy talks that I frequently give.

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I’ll be joining the faculty of Quest University in Fall 2010

Posted on December 21st, 2009 — permalink

Last week, I flew out to Squamish, BC to interview for a faculty position at Quest University. Two days after I returned, they called me to offer me the job, and I accepted it. Next summer (July 2010), Alyson and I will be moving to Squamish, and starting next Fall, I’ll be a Tutor of Physics at Quest. As far as I can tell, this is my dream job.

Although there have been moments where I questioned this, I have long considered it my calling to teach at the college level at a small liberal arts college. Eight years ago, when the only offer I had was at a large research University, I thought I could make that work— and I almost did. Two and a half years ago, after the quashing of the notion that I could stay forever at a research University, I thought I was never going to be able to work at my true calling, and I took up a (enjoyable and rewarding) backup plan. Half a year ago, when booted out of my backup plan, I despaired that I would ever be able to do anything but “just make money”.

So why do I think Quest is my dream job? I sent out applications to 14 small colleges, 13 of which were in the US, a couple of months ago. I didn’t apply to large research universities at all this time around. However, I’m in that awkward position of being somebody who’s 13 years past his PhD and not a superstar. It’s hard for colleges to hire somebody like me because they have to figure out if they should evaluate me for tenure straightaway, and, crucially, because there is a tremendous oversupply of extremely capable and extremely well-resumed young physics PhDs out there that they can hire for less money. The competition is stiff, and since my realistic and non-superstar resume was competing with extrapolations from very high-end post-docs, I knew it was a long shot. However, even at the beginning, I could tell that Quest was a different sort of place from even most of the small liberal arts colleges. And, I believe it was some of those differences that both made the place so attractive to me and made me “hireable”.

The two single most important things about Quest are this. First, it’s a small liberal arts undergraduate college (enrollment currently in the 200’s, with a target of 600 to 800 in the next five years). (It turns out that while small, secular, independent liberal arts colleges are all over the place in the USA, Quest is unique in Canada.) Second, it’s a new college. Indeed, it’s only had students for three years, so nobody has graduated from there yet! What’s more, not only is it new and thus free of the notion that “we’ve always done things this way here”, but it was also deliberately founded with the best modern understanding of what really makes for a great undergraduate education.

Like Colorado College, Quest operates on the block plan. Students take only one class at a time, and they completely focus on it for three and a half weeks. I don’t have much direct experience with this myself (the closest I’ve been is teaching introductory astronomy over the course of five weeks at Vanderbilt during the Summer term), but I have talked to a number of people who find that they like this model of coursework far better than the traditional “scattered attention over a semester” model. And, given my own tendency to get into something and to want to hyperfocus on it, it appeals to me.

When I was sending out applications, I had to edit my “statement of teaching philosophy” a bit. Originally, I had a statement to the effect of “modern physics educational research has shown that straight lecturing is not an effective way to teach physics courses”. I realized that that statement might directly offend people on the committees that would be reading my applications, and stated it more cagily. (”Much recent research into physics and astronomy education has shown that the most effective use of class time comes when students actively engage the material.”) Quest, however, contained more or less the same original statement in their job advertisement. This was clearly a place that “gets it”. When I visited Quest, I was quite impressed. The faculty members I met with were dynamic and intelligent, and truly cared about undergraduate education as their primary creative endeavor. They were high on the institution, and they were high on their students. Indeed, I was also impressed with the students I met, both in the “sample class” I taught, and when I chatted with a few of them and some others afterwards during lunch. I would say that I was even more impressed by these students as a group than I was by the students at Pomona I met with when I applied there several years ago— previously, that was the group of students I’d met during job interviews who impressed me the most. (Of course, the most impressive undergraduate students I’ve worked with over the years include Jessica Hodges, James Schlaerth, Naved Mahmud, Jonathan Stricker, Andrew Collazzi, Anders Jensen, and Cameron Pittman… i.e. the ones who’ve done research with me!) (When I interviewed at Vanderbilt nine years ago, I met some graduate students, but I didn’t teach a “sample class”, nor did I meet any undergraduates.)

Quest also doesn’t do tenure. Many would view this as a disadvantage. And, indeed, I can fully appreciate the value of the perk of having a permanent assured job. But, I’ve been on the other end of tenure, and anybody who read my blog a few years ago knows that I suffered greatly because of it. A friend of mine once said that she didn’t know anybody who went through the tenure process without having it f–k them up severely. While many point to the “deadwood” problem as the “flaw” of tenure, David Helfand (the current president of Quest) said what I also think— that that problem is overblown, and is only something like a 10% effect. The real problems of tenure is that it limits academic freedom for pre-tenure people. I don’t know that that is such a severe problem in the sciences, but you can easily imagine how in any department the young, bright, and dynamic faculty may have to constantly censor themselves to avoid torquing off a powerful ego in their department. Heaven knows that I didn’t manage keep my mouth shut, and freely offended several senior professors in my department… and I still believe that had I received an NSF grant, I would have had no problem getting tenure at Vanderbilt, because there were enough other senior professors who agreed with the things I was saying. However, tenure did put tremendous stress and pressure on me, and that stress and despair undermined my research productivity my last few years at Vanderbilt. All in all, by the end, for me, the tenure system had nothing but negative effects while I was at Vanderbilt. As long as Quest does real faculty evaluations that really evaluate whether they are doing what they’re supposed to be doing well (and I believe that it will do this), I’m just as happy to be shut of the whole tenure system.

Indeed, I suspect the lack of tenure made it much easier for Quest to consider me than it would have for other colleges. They didn’t have to look at somebody 13 years out from his PhD with six years experience teaching at the University level and think about tenure clocks or any of that. I’m just one more contracted Tutor. (Oh, and, they call them Tutors there in order to emphasize that our role is not to “profess”, but to enable and aid the students in learning how to think and how to learn.)

A lot of colleges and Universities include a “writing across the curriculum” initiative. When I learned during my final interview that Quest is trying to start a “quantitative reasoning across the curriculum” initiative in addition to this, I almost fell over under the “this must be too good to be true” response. I’ve long bemoaned that Universities understand the value of writing while missing the equally important value of quantitative reasoning.

Because Quest is not only a new University, but a small University where faculty have no choice but to teach some courses outside of the “straight and narrow” of their fields, I am very sure I’ll be able not only to challenge myself by teaching some of their Foundation classes, but that I’ll be able to create new and interesting courses that might transcend what you’d fine at a “normal” Physics department. I’m not just thinking about an undergraduate fluid mechanics course (which one student at lunch asked for while I was visiting), but I may one day before long get to teach a class about the science found in Tom Stoppard’s plays…. It’s all opportunity, it’s all exciting future.

When I left Quest this last week, I felt that this was the place where I was supposed to be. It almost made me think that perhaps there was some Plan at work, that I taught at a research University for six years not because I went where I had the offer (instead of to the sort of place I thought I really wanted to teach), but because it was preparing me while Quest University was in the process of being created. (I don’t really believe that; if you are lucky, it’s not a mystical force, but it’s merely because, in the words of Spock, “random chance seems to have operated in [your] favor”.) I was very excited when they called me on the phone to offer me the job, and the only reason I didn’t accept it on the spot was that my wife was napping, and I did want to check in with her before accepting a job that was going to include a move to western Canada.

I still don’t know everything I’m going to be doing during the first half of 2010, but next Summer I’ll be moving to Squamish, and next fall I’ll be a Tutor in Physics at Quest University.

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“Dr. Knop Talks Astronomy” — archived on the web

Posted on December 15th, 2009 — permalink

I give regular talks in a series entitled “Dr. Knop Talks Astronomy” as part of MICA’s public events. These talks are in Second Life, so people from all over the place can come to them.

if you’ve missed them, and want to catch up on them, at the site above slides from most of my talks are archived, as well as MP3 files of the audio in many cases. However, there are now three of the talks online that have been recorded fully in video. Of course, it’s not the same as being there, since you can’t ask questions and interact, but it might give you a sense of what goes on at these things.

The first one is a talk about how we know that Dark Matter exists that I gave several months ago; this talk is online at PookyMedia.

More recently, Geo Meek has recorded my most two recent talks, and there is now a Dr. Knop Talks Astronomy channel at livestream. The two talks online there are one all about redshift (the Doppler shift, gravitational redshift, cosmological redshift), and my talk a few days ago about black hole misconceptions. Special thanks to Spike McPhee (aka Paradox Olbers) for supporting this latter effort!

Joe Bob Says Check It Out!

(Update: it looks like the black hole talk is not online at livestream yet, as of 2009-12-15 13:40. However, I believe it will be before too long.)

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Climategate is a tempest in a teapot, but it may lead to worst tempests

Posted on December 6th, 2009 — permalink

The Tennessean has been publishing numerous letters to the editor and editorial columns talking about how “climategate” supposedly shows that anthropogenic global warming is a fraud. It’s extremely frustrating. That conclusion can only be drawn from a deep misunderstanding about how science works and the language of scientists used in the e-mails, but sadly it seems that newspapers are interested more in presenting “both sides” than getting to the truth of it. Today, there is an egregious column from David Lipscomb professor Richard Grant repeats the same tired arguments global warming denialists have already been using, and completely misunderstands the impacts of the supposed revelations from the leaked University of East Anglia emails.

It’s very frustrating myself to watch this happen. The people who are trumpeting about this are ignorant about science. When I read the excerpts from the emails that are supposedly the smoking gun about climate change being a fraud, I do not see anything extremely alarming. What’s more, even if I did, the evidence for climate change has not come completely from the University of East Anglia; it has come from all over the place. If it hadn’t, scientists would not be accepting it as strongly as they do! And, yet, the newspaper coverage of this is covering the scandal, the controversy… it does not seek to illuminate the truth of the situation, to explain what is really going on. And, this of course lends fuel to the politicians who are exploiting global warming denialism for their own ends. (To be fair, there are also politicians who exploit the fact of human-caused global warming for their own ends! That doesn’t make the conclusions wrong, however.) It is sad to me to see so many in our population being manipulated in a way that will allow us as a society to act in ways that may very likely cause us tremendous pain in future decades.

Here is the text of a letter to the editor I wrote to the Tennessean in response. I don’t know if it will get published; I hope it does, of course, because many more people read the Tennessean letters to the editor than this blog.

The numerous letters and columns that have been written suggesting that “climategate” undermines conclusions about anthropogenic global warming are all getting it very wrong. There are two important points.

First, no matter what the researchers said when venting frustrations in private e-mail, their final actions in what data was published showed no misconduct. Nothing was suppressed, nothing was fudged. The impact of the supposedly revealing emails is vastly overstated by those who deny man-made global warming.

Second, and perhaps more importantly, even if we throw out all of the climate data and conclusions from the researchers in question, the conclusions still stand. This is an important point about how science works. Cold Fusion generated a lot of headlines in the 1980’s when first reported, but ultimately didn’t stand because no independent scientists could reproduce the results. With climate change, there are multiple independent teams who have data that all point to the same conclusions. Even if something were to cast doubt on conclusions of the University of East Anglia, that does not in any way affect the independent data of the USA’s NOAA, for example.

The climate change data is still robust. The leaked emails only show informal communication using the jargon scientists use, and normal human frustration with how obstinate so many seem to be against accepting the fact of man-made global warming. Given how science works, these emails do not in any way undermine those conclusions. It is only at our peril that we use these leaked emails to further political ends.

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The Moon in “Heroes” is VERY different from our Moon.

Posted on October 25th, 2009 — permalink

My wife and I tend to watch TV shows a year after they come out; we rent the DVDs from Netflix and watch them then. We’re right now working our way through the third seasons of Heroes. If you’ve watched even the first season of Heroes, you know that Eclipses are a Big Deal and somehow cause or affect superpowers in humans. Well, there’s another total solar eclipse coming in Season 3. Here’s a screenshot (also showing a vapor ring left behind as Nathan Patrelli took off flying at high speed) of the moon about to eclipse the Sun:

OK, first, the good. Yes, the Moon is apparently about the same size as the Sun in the sky. (Yeah, the Sun looks a little bigger, but that’s probably because of the glare. There’s about to be a total eclipse, so they’ve got to have about the same apparent size. In any event, the size is close.)

Now, the bad. When the moon is that close to the Sun in the sky, it is a tiny, tiny, tiny, very thin crescent, basically a new moon. You will not see it at all, until it starts to actively block out the Sun. The reason for this is that since they’re so close to each other in a sky, it’s almost a straight line from the Earth to the Moon to the Sun. The distance to the Moon is much less, so the Moon is between us and the Sun. Thus, the side lit up by the Sun is the far side of the Moon from us.

Yet, here, instead of an almost-new moon, we see an almost-half-full moon! For half of the moon to be lit by the Sun when we see the two right next to each other in the sky, the moon would have to be at about the same distance from us as the Sun…. Well, it’s not quite half, so it’s a little closer, but we’re talking inside the orbit of Mercury here. And, for the Moon to look as big as as the Sun when it’s that far away, it will have to be physically almost as big as the Sun!

In our Universe, the Moon is a satellite of the Earth, about 1/4 the diameter of the Earth, and orbiting the Earth. The Sun is about 100 times the diameter of the Earth. The reason they look about the same size in the sky is because the Moon is so much closer.

From the evidence in the image above, however, the Earth of the Heroes Universe is very, very strange. They orbit a binary “star” system, including the Sun and the Moon… although the Moon is not a satellite of the Earth at all, but a binary partner to the Sun. However, the Heroes Universe Moon is an extremely bizarre object, for despite being so large, it does not shed any light of its own in the optical. It’s clearly not a large gas cloud, for you can see by looking at it that it’s a solid object with “seas” and craters and all of that. So, it’s something that has somehow managed to be as big as the Sun without triggering fusion inside to make it glow.

Wow.

Well, given that all these superpowers work, we already knew they were operating under different laws of Physics, so I guess we shouldn’t be surprised.

My only fear is that people watching the show don’t realize that the producers are being very clever here in showing us that the Moon is a gigantic object that is nearly as far away as the Sun, very different from the case in our own world. I fear that some people watching might either think that the producers of the show have done the typical Hollywood thing and made a boner of a mistake, or may think that it’s entirely reasonable to see a near-half Moon right next to the Sun in the sky. I hope in upcoming episodes there will be dialog between the characters that more clearly reveals the nature of their Moon as a star-sized object close to the Sun.

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First impressions of Leiden

Posted on October 4th, 2009 — permalink

I’m out in Leiden for the next three days for the AMUSE Workshop. AMUSE is an evolution of MUSE, a software framework for integrating various different modules of stellar modeling together. So-called “N-body models” model the orbits of lots (”N” being a large number) of stars orbiting around each other as a result of their mutual gravity. They’re great as far as they go, but they aren’t all of the physics. If the timescale of your simulation goes on long enough, eventually you’re going to have to take into account stellar evolution– the fact that more massive stars live shorter lives and go supernova, spewing most of their mass out into interstellar gas. If you’re dealing with dense systems (think the Galactic core, or globular clusters), you have to take into account “strong interactions” between stars, which most N-body codes don’t handle by themselves. And, if the systems are really dense, you may have to take into account mergers of stars, which involves hydrodynamics. Additionally, there is gas in galaxies, which also involves hydrodynamics.

Traditionally, all of these different areas are modeled separately. Sure, there is definitely some overlap between N-body codes and few-body strong-interaction codes. However, the goal of MUSE was to make it possible for people who write disparate simulations to link them together for a more realistic simulation that needs to take into account multiple systems.

All of which is why I’m here. But the real reason I want to write this is to just dump my first impressions of Leiden:

• This is a very bike friendly city! There are paths for bikes and motorized scooters, bike lanes, and massive bike parking lots all over the place. And you see huge numbers of bikers riding around. But very few of them are wearing helmets.
• The Dutch language is much more mystifying to me as an American than either French or Spanish. Now, yes, I did study French all the way through junior high and high school, so I’m not coming at French as a complete ignorant. But I certainly find Spanish names easier to wrap my brain around than Dutch names. However, it’s not as hard as Sweden, where the collection of letters that form street names just would not stick in my brain with the linguistic substructure I’ve built in there all my life.
• Trash! There is litter, and there are piles of trash, all over the streets.

Update 2009/10/06: It turns out that the trash was a transient thing. October 3 is an annual festival that Leiden celebrates for its liberation from Spain a few hundred years ago. That festival can go on for days and culminates on October 3. I was seeing the aftermath of Saturday night’s festivities when I arrived on Sunday, October 4. I happened to arrive on exactly the worst day for trash in the streets…!

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