Galactic Interactions

Shakepseare & Relativity in-world this weekend

Posted on May 28th, 2009 — permalink

I’m going to be busy this weekend with a public outreach talk and some Shakespeare performances.

Saturday morning at 10AM SLT/PDT, I’ll be giving a talk entitled Time dilation and simultaneity in Special Relativity. This is part of the regular “Dr. Knop Talks Astronomy” public-outreach talk series given by MICA. If you’re curious about just why it is that moving clocks run slow in special relativity, drop by and I’ll explain it. You don’t need any math to understand the basics; with just early high-school algebra (the Pythagorean Theorem), you can even understand the equation for how slow clocks run. The talk will be at the MICA Large Amphitheater (StellaNova (213, 210, 32)).

Then, Saturday and Sunday from 4PM-5PM, Avatar Repertory Theater will be performing scenes from several Shakespeare plays in our “Shakespeare at the Pavilion” performance, in association with the San Diego City sim. We’ll do scenes from Twelfth Night, Julius Caesar, Hamlet, As You Like It, and A Midsummer Night’s Dream. See the A.R.T. site for more information.

I remind everybody that a Second Life account is free. Here is one place you can register for an account— that’s the registration portal for the SciLands, a contiguous group of regions of which MICA is a member. That will take you to the SciLands’ orientation spot. Both of the events above will use Second Life Voice, but you don’t need a microphone or a headset; you’ll just need your standard computer speakers to hear what’s going on. There are Second Life viewer applications for Linux, MacOs, and Windows.

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When Stars Collide

Posted on May 26th, 2009 — permalink

When I’ve given talks about colliding galaxies, I always start out by pointing that that the stars within a galaxy basically never collide with each other. This is, of course, an oversimplification….

You may have seen a “scale model” of the Solar System. It gives you a sense of how amazingly spread out things are… especially after you’ve made the hike to get to Saturn, never mind Uranus, Neptune, or the Kuiper Belt. But you never see a scale model of the nearby stars. Why? because things are even more amazingly spread out. Suppose I wanted to make such a scale model, and, here in Nashville, TN, I used a tennis ball to represent the Sun. To represent the nearest star, α Centauri, I’d need another tennis ball that is in New York City. Stars are really, really far apart from each other. Our galaxy is mostly empty space. (Well, actually it’s mostly dark matter, but within the disk of the galaxy, the mass density is more stars than dark matter. And, between the stars, there is interstellar gas, but the density of that gas is much lower than the density of gas in the best vacuum chamber we’ve built on Earth.)

However, there are places where this isn’t strictly true. We see some stars in globular clusters that are more massive than stars that have any business still being around in that globular cluster. (That is, globular cluster stars were all formed 11-13 billion years ago. Stars with higher mass have shorter lifetimes, so any star above a certain mass cutoff isn’t seen in a globular cluster.) One very likely explanation for this is that these stars are the result of a merger between two lower-mass stars.

It may also be possible in some very rich young clusters of stars that stars may collide with each other before the cluster disperses. The black hole at the center of our galaxy may very rarely “eat” a star. (No, we haven’t seen this happen.)

Last week, Jamie Lombardi of Allegheny college gave a seminar in Second Life as part of the MICA professional seminar series entitled “The Hydrodynamics of Runaway Collisions.” At the very beginning of the talk, he had to clarify that he was in fact talking about colliding stars. I give a lot of public-outreach astronomy talks for MICA (a different series, obviously, from the serious of professional seminars), and I have given a couple of talks about colliding galaxies. My own history as an astronomer leads me to think “collisions” to mean “between galaxies”– and the hydrodynamics, then, must be referring to the gas processes that might, say, feed an AGN.

However, cool things can happen when three stars have a close enough pass that their envelopes start to spill on to each other. Sometimes, two of the stars will merge (while the third one in the collision is ejected). Some of the gas is lost, but much of it stays behind in a more massive star. The timescale for these collisions is short enough that the stars will not evolve appreciably during the collision, so this may well be a way that you can make a star that’s more massive than what would naturally form out of star formation nowadays— especially if you can chain together several collisions. What Jamie was talking about, of course, probably only applies in very young, very rich clusters. The globular clusters in our Galaxy today are too old to have the kind of massive stars that Jamie was focusing on in his talk, and most of the star forming clusters nowadays have several orders of magnitude fewer stars than globular clusters do. But, globular clusters were once young….

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This Saturday at 10AM PDT in SL : “How We Know Dark Matter Exists”

Posted on April 29th, 2009 — permalink

As part of my regular Dr. Knop Talks Astronomy series of public astronomy lectures in Second Life, this coming Saturday I’ll be talking about how we know that Dark Matter really exists.

The talk will be at the Large Ampitheater on StellaNova. Note that a Second Life account is completely free! You can register for an account here. This is the “SciLands” entry portal, which will put you at the SciLands own orientation island. (StellaNova, the sim of MICA, is part of the SciLands.)

Here’s a description of the talk:

Modern cosmology tells us that the majority of the Universe is made up of stuff whose nature is largely unknown to us. Two thirds of it is Dark Energy; most of the rest is Dark Matter, the subject of this talk. Dark Matter interacts with normal matter through gravity, but otherwise it interacts hardly at all. Yet, we have very high confidence that this mysterious Dark Matter really does exist. Because it doesn’t interact with light, we haven’t seen it glowing, nor have we observed it absorbing background light as we’ve seen with dust clouds. All of the evidence we have for Dark Matter comes from its gravitational interaction with other matter, and with light. Yet, this evidence is extremely compelling. In this talk, I will attempt to convince you that there is no reasonable doubt that Dark Matter exists.

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Popular Astronomy Talk in Second Life, Friday 8AM PDT (11AM EDT)

Posted on October 9th, 2008 — permalink

I’ll be giving a talk entitled: “We Are Starstuff: the Cosmic Origins of the Chemical Elements” as a part of the MICA public talks series. The talk will be at the Galaxy Dome in Spaceport Bravo.

Remember, a Second Life account is free!

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“Planets Around Other Stars” — talk in Second Life this Friday at 8am PDT

Posted on July 31st, 2008 — permalink

I’ll be giving the latest in the “Dr. Knop Talks Astronomy” series of talks associated with MICA this Friday at 8am SLT (aka PDT). The talk will be at the Galaxy Dome in Spaceport Bravo. The topic is Planets Around Other Stars:

Until the last decade of the 20th Century, we knew of exactly one star system that had planets: our own. At the dawn of the 21st Century, we knew about a few handfuls of exoplanets, or planets around other stars. Today, we know about more than 200. In this talk, I’ll describe the history of exoplanet searches and discoveries, I’ll describe the methods that we have used to find planets, and I’ll give you an update about the current count and nature of exoplanets that are out there.

Remember that a basic Second Life account is free!

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SL5B Science Panel, Today, 5PM PST

Posted on July 1st, 2008 — permalink

I’m going to be one of five panelists on the “SL5B Science Panel”. What is SL5B, you ask? Second Life’s Fifth Birthday! It was five years ago that Second Life started it’s open beta. Everybody talks about Second Life as being so “new” that it’s hard to believe that it’s been around that long.

Indeed, it’s hard for me to believe that I’ve been a part of Linden Lab for approaching 20% of the time that Second Life has been live…

The panel will be at SL5B Linked (181, 190, 25).

Panelists on the SL5B panel are:

Ourania Fizgig (RL: Adrienne Gauthier) is an instructional technologist in the Astronomy Department at the University of Arizona. She brings ASTRO101 students into Second Life and is also managing the International Year of Astronomy 2009’s presence in world.

Troy McLuhan produces multimedia exhibitions and events in Second Life. His background in applied math and physics, and Purdue PhD in astrodynamics serve him well in his active role in the Science Center group as well as his space related initiatives. http://www.troymcconaghy.com.

Pema Pera is an astrophysicist and head of the program of interdisciplinary studies, Institute for Advanced Study, Princeton, NJ, USA, and involved with MICA, The Meta Institute for Computational Astrophysics, a group of astrophysicists and others interested in astrophysics. He is also interested in building virtual communities, and in computational science as well as in broadly interdisciplinary studies. See his paper on http://arxiv.org/abs/0712.1655 (click on “pdf” for the full article).

Prospero Linden is Rob Knop in real life. Until year ago, he was a professional astronomer, first on the team that discovered the acceleration of the Universe’s expansion, and then an assistant professor at Vanderbilt University. Last year he joined the engineering team at Linden Lab. He gives monthly astronomy outreach talks (as his alt, Prospero Frobozz) in association with MICA, the Meta-Institute of Computational Astronomy. http://www.sonic.net/~rknop/blog.

Bjorlyn Loon (Lynn Cullens in RL) has been writing and communicating about science and technology for 30 years. She has worked in archaeology, carnivore studies, historic preservation and the history of science, but has a real passion for biology and conservation. In Second Life, Bjorlyn has directed the Communications Team for Burning Life, founded and manages the Science Friday group and sim for Ira Flatow, was a recent award winner with The Tech in SL, and now is the full time Director of Communications for Metanomics, the popular business and policy program on virtual worlds.

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Shakespeare in Second Life : Staged Reading of “Twelfth Night”

Posted on June 23rd, 2008 — permalink

As many of you know, I’ve performed already in the first two “miniproductions” with the SL Shakespeare Company.

Currently, SLSC is putting on a staged reading of Twelfth Night. They are doing one act each weekend, with three performances of each act. Every time there is a different cast, and even when there are the same people they are reading different roles. I was in one of the three performances of Act I, and will be in a handful of other performances, although because of my schedule I’m not going to be in very many of these.

See the SLSC website for showtimes and more information.

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Public astronomy talk in Second Life, “Kepler, Newton, and Einstein: ‘Wrong’ Theories and the Progress of Science”

Posted on June 11th, 2008 — permalink

I’ll be giving this talk in Second Life tomorrow (Thursday) at 10AM PDT (in-world time). This talk was originally scheduled for last Friday, but Second Life was having serious problems at the time as a result of networking problems from our upstream ISP.

The talk will be part of the Dr. Knop Talks Astronomy series hosted by MICA. It will be at the Galaxy Dome in Spaceport Bravo.

Remember, basic Second Life accounts are free, as is the client software!

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Technical talk on Dark Energy and Vacuum Fluctuations in Second Life this Friday

Posted on May 8th, 2008 — permalink

In addition to the popular-level astronomy talks I’ve started doing as part of MICA, there will also be regular “journal clubs.” This is something you’ll see in physics and astronomy departments sometimes: people take an interesting paper from the recent literature (really, from preprints nowadays), and lead a discussion about it with their colleagues. It’s one way of trying to keep up with some of what’s going on in the literature, and it’s also a way that one scientist can share his particular area of interest with his immediate colleagues.

This Friday, George Djorgovski will be leading a journal club in Second Life at 8AM SLT (pactific time) on the paper Dark Energy from Vacuum Fluctuations by Djorgovski and Gurzadyan. Note that while in this case, the author of the paper is talking about his own paper, that’s not always the case. In journal clubs I’ve been too, sometimes people talk about their own work, and sometimes they talk about other interesting papers from the literature. For instance, when I was at Vanderbilt and still working with the Supernova Cosmology Project (which used optical and infrared astronomical data), I gave a journal club about the WMAP 3-year results — very releavant to cosmology and my work, but not something in which I was involved.

The journal club will be where all of the MICA meetings currently happen, at the ISM Workshop in Spaceport Bravo.

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Popular Astronomy Talk in Second Life : The Death of Stars (2008-May-02)

Posted on April 28th, 2008 — permalink

I’m going to be giving my second “Dr. Knop Talks Astronomy” popular talk in Second Life as part of the fledgling Meta Institute for Computational Astrophysics.

The talk will be at The Galaxy Dome in Spaceport Bravo, this Friday (May 2) at 8AM pacific time (which is the same as in-world time in Second Life).

Drop by if you’re interested! Here’s the longer description of the talk:

In Fire and In Ice : The Death of Stars

Stars live for millions or billions of years, but they don’t liveforever. When a star reaches the end of its lifetime, spectactular fireworks can result. In this popular talk for interested layman, Dr. Knop will outline what it is that keeps a star together during its lifetime, and what happens to stars of various different sizes when that process finally breaks down. He’ll talk about the ejection of planetary nebulae, the cooling of white dwarves, and the most spectacular of stellar events, supernovae.

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