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dibs_and_dlas

[ website | Brian York's Low-intensity Page ]
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A Nu way of doing things [Mar. 23rd, 2008|06:46 pm]
dibs_and_dlas

Yes, I almost never post at the moment. But right now I’ve just had enough of writing my thesis, and I want to write something else, like a journal entry. So here we are. I expect that I’ll start with a few more general ideas, and then move on to justify the rather bad pun in my title. So, life first, code second (not that that’s the way I actually live, but it’s a good way to organize a journal entry.)

So, what’s going on with my life at the moment (other than writing my thesis of course)? Not too much, I’m afraid. I am making progress on my thesis though, so that’s definitely good news. Three of the five chapters either done or mostly one, and the fourth started, and I’m on target to defend at the end of July. And, my committee has been convinced to continue my funding through the end of August (for those who know something about how things have been going, this counts as a major victory).

Even with my thesis work though, I’m still learning new things. For example, a couple of weeks ago I discovered an excellent tip for those of you who cook. When one is trying to cook something (even if it’s just a simple “dump onions, vegetables, and maybe meat into a frying pan, cook it, and serve with rice, noodles, potatoes, whatever”), it is important to put the frying pan on the stove before turning the stove on, and vitally important to put the frying pan on the stove before adding olive oil and starting to cook your onions. Otherwise, the process becomes a bit messy. Or so it seems to me. Theoretically at least. Because, after all, I haven’t actually done anything like that of course.


Moving on now…

Code StuffCollapse )
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I'm (still) here [Jun. 14th, 2007|10:30 pm]
dibs_and_dlas

Well, I’m alive. And so is my research plan. In fact, my first draft (with figures) is complete. I’m linking to it below so that anyone who’s wondered what I’m doing can take a look at it.

Thesis lite

There are still a few things left to do before it’s finished (in particular, I need to figure out what signal-to-noise I’d need to get an equivalent width limit of 0.3 angstroms for each of the Mg II systems, and how long it would take to reach that SNR with various telescopes). Once I have the times together, I need to put them in a table, and put it in the research plan).

Now, as I said, it’s mostly up there for interest, but if any of you feel like commenting or asking questions, that would also be good. The plan is aimed at the level of the non-specialist astronomer, but I’m hoping that it’s not too specialized for the chemist on my committee. In particular, if you see any astronomical jargon that I use without explanation, then I should probably deal with it. And, of course, if my “motivations” section doesn’t motivate, that’s a problem.

It feels really good to be finished this thing finally. Well, mostly finished anyway. And I don’t even have to send it in until the 20th, so I have a bit of time to revise it (if necessary). And, hopefully, I get a good thesis out of it.

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High-flying post [Nov. 21st, 2006|12:41 am]
dibs_and_dlas
As I write this, Ungava Bay has just gone by below (not that I can see it, since it's dark out), and I'm heading out over the Atlantic. Nice of Scandinavian Air to include a wireless network on their planes (you can't use your cell phone, but wifi is just fine -- go figure). Pity that the provider is discontinuing it in January, but at least that means that my access tonight is free. Sure, I don't have a laptop plug-in (so I'll have to shut down eventually), but still, it's cool. Which is why I'm posting this. I just like the idea of sitting here in a large (but mostly empty) plane, surfing the internet. I never would have thought it would be possible.

Incidentally, I'm told that the flight from Seattle to Copenhagen has some nice views. I'm sure it does, but they certainly aren't obvious when you're flying overnight. And, when I land, I get to head on to Madrid, where I have to go through customs and successfully recognize my suitcase *before* I get to actually call the hotel I'm staying at tonight (tomorrow night? Stupid time zones). Oh well, at least I've been able to check my e-mail on the way....
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What am I doing here? (Part 1) [Oct. 4th, 2006|06:04 pm]
dibs_and_dlas

Ok, so this isn’t really the post about the curiously high metals content (that’s going to be a future part). Instead, this is the post about what I do, what spectra are, how we reduce them, and what we find out from them. If the post is still short enough, I’ll add in a bit about diffuse bands, and our results there so far (they’re published, so I’m quite safe in doing that).

Read on...Collapse )

So now that we’ve found our DLA (and now that you all know what the “damped” part of damped Lyman-α system means), you can do something with it. But, since this has turned out to be another long post, I’ll discuss that in the next part, hopefully in a couple of days.

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Not the update I had planned [Oct. 3rd, 2006|04:06 pm]
dibs_and_dlas

Soon there will be an actual update, involving the work I’m doing, what it means, how it’s done, and a few exciting new developments that are currently underway. Meanwhile, though, I’ve been asked to share a brief moment from a parenting course I was taking last night.

It’s the third week of the course, and the overall theme is about how to talk with children, and (of course) there’s homework, (mostly) involving actually trying to apply what you’ve been working on. So, at the start of the class, we were asked to share about if (and how) we’d applied the ideas from the previous class. My response?

“Well, I didn’t apply any of these techniques in talking with my child, but I did use them in talking with an employee of the Ministry of Children and Families. That’s the same thing, right?” The instructor, who has some experience with the ministry, agreed (of course).

Ok, that’s it for now. I’m off again to look at the case of the curiously high metals content.

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Why is Dark Matter Cold? [Sep. 4th, 2006|11:58 pm]
dibs_and_dlas

First off, for all those interested in the “what is a planet?” debate, I suggest checking out this paper. A good read, and a good take on the subject.

And now, more on Dark MatterCollapse )
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Cold Dark Matter [Aug. 27th, 2006|11:53 am]
dibs_and_dlas
Some of you will already have seen this. Despite all the controversy surrounding Pluto (well, it’s more controversy than you usually get about astronomy), I think that the discovery in that little letter is probably of far greater importance. Of course, explaining why will require a little bit of background.

A not-so-quick summary of cosmology and the cosmic microwave backgroundCollapse )

So, after all this, that’s why this result is so significant. It’ll solve a “controversy” that’s been going on almost as long as “what are the diffuse interstellar bands” (which, I point out modestly, I’m currently working on), and much more relevant to cosmology as a whole.

And what about the “cold” in the title? That’s a distinction for another day.
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Non-work-related Entry [May. 27th, 2006|12:00 pm]
dibs_and_dlas
So, it was gently brought to my attention recently that I should post entries about something other than work. About interesting things going on in my life, about feelings, about ideas. Well, I thought about it and then I realized that there really weren’t many interesting things going on that don’t involve work (occupational hazard of grad school I think), but that I do have ideas to talk about, that have nothing to do with my job, directly at least.

So, universe design.

I recently had a couple of ideas on how things might work in a particular SF universe that I’m designing (rough outline available in the fudge factor article I wrote about it). Now, some details have changed (mostly I got rid of gravity manipulation, probably, because I don’t think I need it, although it might re-appear, and I’ve firmed up the way the jump drive works). In any case, I had some ideas about the way orbital space would be divided up between various planetary nations, and the way freight and passengers would get from the surface to the starships. And I posted these ideas to sfconsim-l (which is actually on yahoogroups now), and the discussion quickly evolved in many unexpected directions. During the discussion, I quickly realized how important a group like that is for anyone trying to create any type of hard-SF setting, mostly because there are a lot of scarily smart people there, and they’re willing to put your math, physics, biology, sociology, etc. through the wringer, and question your unstated assumptions, and help you tighten things up to no end (even if only by letting you know, unambiguously, where you need to break the laws of physics to make things more fun).

I should mention, also, for anyone who’s interested, that the other absolutely-not-to-be-missed resource for anyone who’s doing anything that’s even remotely hard SF is Nyrath’s incredibly detailed and useful atomic rockets web page. This page recently highlighted one of the strange ironies of my own setting — because of the way I handle FTL travel, the biggest, most powerful engines (~35 gigawatts of thrust power, which is nothing compared to most SF rockets) belong to the orbital tugs, and most actual starships have only chemical maneuvering thrusters, or very low-acceleration, low-power, low-Δ-v engines. And my spaceships resemble trains far more than they do anything else — everything is modular. Not to mention that the weapons carried by warships are essentially useless near planets.

The real advantage of Atomic Rockets is that it explains what you’re doing step-by-step, and it puts the equations together in ways that are much easier for me to look up than my textbooks (which were designed to teach physics rather than science-fiction rocketry), and it also makes it easy to fiddle around with my parameters until I have something that looks right (even if it does mean travelling at several light-years per day between stars, then taking another two days or so to go from (roughly) the distance of the Moon back to the Earth).

And, well, sfconsim-l will tell you when you’re breaking the laws of physics, and will mention some of the consequences you might not have noticed about breaking certain laws (so as to avoid the Star Trek problem of having to explain each time why the transporter (or the replicators, or that gadget they put together in ten minutes last episode) can’t solve the problem). And finally, if you run your assumptions past them, and tell them the results you want to get, they’ll usually tell you where you have to break the rules, and what the good places would be to do that with a minimum impact on the way your universe works.

So, now that I’ve rambled on about ideas (a little bit) and good places to hang out if you’re into science fiction (and note that none of it was work-related, except to the extent that I might be thinking about things while I should be working), I’ll sign off again for a little while.
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Super fast papers. [May. 24th, 2006|04:38 pm]
dibs_and_dlas
As usual, the pretty version is here.

I guess this about says it all. I’ve got to say though, that I’m impressed by how quickly ApJ Letters works (especially compared to the regular peer-review process). Now granted that only having four pages to look through probably made a difference, but it’s still only about a month from submission to acceptance, which is doing pretty well.
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(no subject) [May. 12th, 2006|09:34 pm]
dibs_and_dlas
As usual, the prettier version is here.

Why is it that I only write journal entries when I’m visiting telescopes?

Actually, mostly it’s because that’s when I’m pretty much guaranteed to have some time with nothing to do except try to stay awake (accompanied by internet access, of course, since astronomers just love running cables up mountains). Not that I’m on a mountain this time….

Actually, right now, I’m in Socorro, New Mexico, home of the VLA (Very Large Array). I just saw it for the first time today (it’s about 100 km outside of Socorro). I’m not actually here to observe on the VLA, of course, much though I might like to.

So, how is radio different from optical? Well, you don’t care about the weather (it’s been cloudy, raining, whatever (even thunderstorms apparently) at Greenbank, but we haven’t even noticed (of course, at higher frequencies you do notice, but we’re not using them). You can observe during the daylight. RFI is nasty (not so much at high frequencies but, again, that’s not what we’re using). The data reduction package (“AIPS++”, now called “CASA”, and we’re using a single-dish package called “DISH”) is just as quirky as IRAF, but involves a whole new learning curve. Of course, you still use FITS files. All hail the mighty FITS file format (seriously, if there’s one development that has made astronomy easier for everyone, the FITS file format is probably that development). Oh, and the telescopes are a lot bigger. Even the VLA’s (individual) antennas are maybe 15 metres across, (and there are 27 of them, spread over about 40 km, which makes for a very impressive sight), and I can’t even imagine Greenbank — a fully-steerable 100 by 110 metre telescope. Araceibo is 300 metres across, but you can’t move it.

Overall, it’s been a productive (if busy) trip, and New Mexico, aside from the heat and dry conditions, is a really nice area (this part of it, anyway). And now I can add another part of astronomy to my list.
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