Wednesday, December 20, 2006

Good MOT, Good MOT!

Okay, so remember the other day when I said we had the brightest trap ever, but couldn't get it to work when we changed the set-up? And how if we didn't change the set-up, we couldn't do the experiment? So we really needed to get it working with the new set-up? Well, we did!

I promised pictures of the super-bright trap, and I took them, just didn't get around to uploading them. But now you can see the super-bright trap, and the new-set-up trap.

But first, for reference, is a picture of what the trap used to always look like (on a good day)

Second is a picture I took of the same monitor, with the same camera (though the camera had been moved slightly, but not significantly closer) on the day after we saw the trap with the naked eye. Believe it or not, the trap was actually even bigger than this at one point, though not much bigger.

The final picture is the trap we got today. It was also slightly bigger than this at one point, but this was a better photo. As you can see, even the weaker new trap is brighter than the kind of trap we used to get.

It always feels like a lot of lot of work to get back to the same place, when we're trying to get the trap going again. This time it took weeks. But the truth is, this represents a major step forward. Because we changed the configuration of the laser beams, and this trap, unlike the old one, can be launched upwards.

The theory behind a trap requires six laser beams: one pointing up, one pointing down, one pointing left, one pointing right, one pointing forward, and one pointing backward. (Actually, our trap is rotated a little so that some beams are diagonal, but lets just ignore that and talk about up and down, forward and back, and left and right.) Up until now, the left pushing beam was simply a reflection of the right pushing beam, and the doward pushing beam was a reflection of the upward pushing beam, and so on. But if you can change the frequencies a little, so that the upward pushing beam is a little higher in frequency than the doward pushing beam, you can arrange for the upward beam to push a little harder than the downward beam... And the atoms are launched upward. It's called an "atomic fountain." This is a necessary part of Ken's experiment. But you can't do it if the downward beam is simply a reflection of the upward beam -- then they're automatically the same frequency.

However, the downward beam is a reflection no more, but a completely independent beam whose frequency can be independently changed. Another hurdle cleared. The impossible experiment is still on.

And we can go on Christmas break without this frustration hanging over our heads.

It feels good.

December Poem

A Child's Christmas in Wales

(It's more a short story than a poem, and I can't possibly quote all of it. I'll link to this copy instead.

I'm just going to quote the end, but please believe me that knowing how it ends does not spoil this particular story.

... And then, at tea the recovered Uncles would be jolly; and the ice cake loomed in the center of the table like a marble grave. Auntie Hannah laced her tea with rum, because it was only once a year.

Bring out the tall tales now that we told by the fire as the gaslight bubbled like a diver. Ghosts whooed like owls in the long nights when I dared not look over my shoulder; animals lurked in the cubbyhole under the stairs and the gas meter ticked. And I remember that we went singing carols once, when there wasn't the shaving of a moon to light the flying streets. At the end of a long road was a drive that led to a large house, and we stumbled up the darkness of the drive that night, each one of us afraid, each one holding a stone in his hand in case, and all of us too brave to say a word. The wind through the trees made noises as of old and unpleasant and maybe webfooted men wheezing in caves. We reached the black bulk of the house.
   "What shall we give them? Hark the Herald?"
   "No," Jack said, "Good King Wencelas. I'll count three." One, two three, and we began to sing, our voices high and seemingly distant in the snow-felted darkness round the house that was occupied by nobody we knew. We stood close together, near the dark door. Good King Wencelas looked out On the Feast of Stephen ... And then a small, dry voice, like the voice of someone who has not spoken for a long time, joined our singing: a small, dry, eggshell voice from the other side of the door: a small dry voice through the keyhole. And when we stopped running we were outside our house; the front room was lovely; balloons floated under the hot-water-bottle-gulping gas; everything was good again and shone over the town.
   "Perhaps it was a ghost," Jim said.
   "Perhaps it was trolls," Dan said, who was always reading.
   "Let's go in and see if there's any jelly left," Jack said. And we did that.

Always on Christmas night there was music. An uncle played the fiddle, a cousin sang "Cherry Ripe," and another uncle sang "Drake's Drum." It was very warm in the little house. Auntie Hannah, who had got on to the parsnip wine, sang a song about Bleeding Hearts and Death, and then another in which she said her heart was like a Bird's Nest; and then everybody laughed again; and then I went to bed. Looking through my bedroom window, out into the moonlight and the unending smoke-colored snow, I could see the lights in the windows of all the other houses on our hill and hear the music rising from them up the long, steady falling night. I turned the gas down, I got into bed. I said some words to the close and holy darkness, and then I slept.

Tuesday, December 12, 2006

Good News and Bad News

The good news is, yesterday we got the biggest, brightest trap we've ever seen. It took up half the camera's view. Its brightness saturated both cameras and drowned out all other light in the chamber in the pictures. It looked like the sun. It looked like it was going to eat the lab. Our advisor asked us why it was so much bigger, and Ken said "Because we rock?"

Here's the thing -- it was so bright, you could even see it with your naked eye. The reason that is surprising is because it glows in infrared.

"Wait, how can you see infrared with the naked eye?" you ask. Well, the eye's response doesn't cut off sharply at a certain wavelength. It just gets less and less sensitive as you go to longer and longer wavelength. Our light is far enough past the peak sensetivity of the red-receptors in your eye to qualify for the term "infrared," but the eye still has some sensetivity to it. In other words, if it's really bright, you can still see it.

The trap was that bright.

Somehow seeing something like that with your naked eye is much more impressive than merely seeing it on a screen or through a viewer. You know it's not a special effect. It's like -- wow, there's a ghostly glowing red dot just hovering in the center of our vacuum chamber. Okay, I believe in quantum mechanics now.

Nothing else could possibly explain that.

The bad news is, we got this incredible trap by going back to the old set up. See, the way we usually get a trap involves having laser beams that go through the trap (it's partly transparent), hit a mirror, and then go through it again from the other direction. What we need to do now, for reasons I won't get into, is have one beam going through it from one direction, and a separate (but identical) beam going through it from the other direction.

When we reflect one beam back on itself, the trap works, and works spectacularly. When we take off the reflectors and send a supposedly identical beam in from that direction, it doesn't work at all. How can that be?

So that's where we are now, the frustrating mystery we are still trying to solve. But seeing the largest trap ever, and seeing it with our naked eye, makes up for the frustration a little.

For reference this post has a picture of what the trap normally looks like on our TV screen. Yesterday, it took up, literally, about a third of that screen. So, huge. I'll bring a camera in today... And here is a picture of what a trap looks like when you look at it with your naked eye. The difference is, theirs is a sodium trap, and sodium glows with visible yellow light, which makes it much easier to see than our infrared glow. But other than appearing redder and dimmer, that's just what ours looked like.

Saturday, December 09, 2006

Things that are Nerdy

Okay, I know the "breaking news: water on Mars" thing was kinda ridiculous. I mean, since it really was news, you probably saw something about from real journalists, and didn't need my link. What can I say? I was excited. In my opinion, nothing could possibly affect the course of history as much as life on other planets, whether human (someday) or alien -- even bacteria. And Stephen Hawking agrees with me. So there.

Meanwhile, Nasa's putting out press releases about plans for a moonbase.

There's a lot of "why" in the discussion that links to, that I really don't comprehend. Why go to the moon? Why hold the Superbowl? Why fight wars? Why try to build quantum computers? Why make Bond movies? When you think of all of the ridiculous things the human race spends billions of dollars on, doesn't a moonbase sound supremely rational in comparison? I know, people say we could better spend NASA's budget on things like aid for African countries dealing with famine and disease. But number one, we wouldn't spend the money on aid for Africa; we'd more likely spend it on weapons research. Or should we give it back to the taxpayers so they can spend it on tooth whitening systems and Christmas presents for their pets? You know it's going to get spent on something ridiculous regardless, right? And number two, even if it were going to go toward aid for Africa, it could only help a small part of single generation... Which is certainly worth doing, but isn't it also worth doing something that could potentially change the destiny of all of the human generations to come?

Um, just in case I offended anyone there: I've bought tooth whitening systems and presents for my pets too. I'm not saying there's anything horrible about that. Just the national teeth-whitening project we're all engaged in is perhaps slightly more ridiculous than a national space exploration project.

That's all the space news I've got, but there are a couple of more links I've been saving up, so I'll sqeeze them into this post as a part of an overall "nerdiness" theme.

Scientists trying to predict the future

Comic books: Joss Whedon is writing one apparently to be titled "Buffy: Season Eight".

For those who watched the Sci-Fi channel's reality show "Who Wants to be a Superhero?" the comic book based on the winner's character has been delayed again.

I'm planning to read both of those comic books, but right now the only one I read is The Walking Dead. That link goes to a review of the first issue that I agree with, so I don't have to write my own review. Except he says he doesn't like zombie movies, and, ever since I started hanging out with Ken, I do.

I do read lots of comic strips. And since I am a protophysicist, I'm gonna link to Zippy the Pinhead talking about string theory every now, and then.

I also think the Brewster Rockit Space Guy story line beginning here is funny, but the website is annoying. Just lie when they ask you for personal information.

Man, I am such a nerd.

Thursday, December 07, 2006

Canals on Mars?

A riverbed on Mars where there was none before.

It might mean life, or it might just make life a lot easier for future Mars colonists...

Tuesday, December 05, 2006

A New Project

So, you all know by now that research is frustrating, right? The project that was supposed to be my thesis... Well, I was spinning my wheels on that for a long time. Couldn't get any traction. When we finally, finally understood the theoretical description of our problem, we discovered that 1: the experimental device we were trying to build wasn't going to work (although not for the reasons I had thought it wouldn't) and 2: the theory behind wasn't new. Other people had already done these calculations.

Ugh, that's very vague. I never know how much I can say about my actual research. I mean, in science, you're supposed to publish in peer reviewed journals, not blogs. But I think it's okay to tell you that I was working on a new kind of optical gyroscope.

Ordinary optical gyroscopes, usually called ring laser gyroscopes, are pretty simple, in principle. Basically, when you rotate a certain type of laser, the frequency of the light coming out of it changes. If you want to know how fast you're rotating, measure the frequency of your laser. This is useful for navigation. Keep track of how fast you're turning and for how long, and you always know what direction you're facing. You can know really accurately, enough to navigate by dead reckoning alone. So all of these airplanes and ships and satellites carry little lasers on board now; optical gyroscopes are pretty standard, apparently.

Anyway, we were supposed to be building a more sensitive optical gyroscope, capable of detecting even very tiny rotations. But it turns out that the effect we thought would simply enhance the sensitivity has a lot of other consequences as well -- like making the frequency measurement much harder to do accurately. And the conditions under which this effect happens turn out to be narrow and hard to realize in practice, and realizing them handicaps the sensitivity in other ways. Which explains why we never managed to demonstrate the increased sensitivity experimentally.

So. End of story, right? So much for my thesis. I've been at loose ends now for a couple of months, wondering if I was ever going to graduate, if I had to start all over, worn out and kind of burned out by the whole saga of the gyroscope. (And meanwhile working on the trap, which is a two person job, with Ken. The trap is always, always frustrating. About two hundred pieces of equipment have to be working all at once in order to trap atoms at all, and optimizing them all takes half a day for two people, even when things are working well, which is not very often. And then when you change anything, it can take days or weeks or months to get the trap back, as you try to track down the problem among all those parts... We've recently changed some things. Ken found a better way of doing what he's trying to do with the trap, in some papers. But it's So. Much. Work.)

To sum up: Arghh! Damnit! Arrrrghh!

But the effect that was supposed to make the gyroscope more sensitive, the effect that other people have already discovered and written about? In trying to understand it, a question occured to us (well, to my advisor) to which we can't seem to find any answer in the literature. Nor is the answer obvious from theory. At first this seemed like bad news -- we still don't totally understand! But now my advisor has given me the assignment of attempting to answer the question experimentally. The fact that no one else seems to know the answer means that the result of such an experiment would potentially be publishable... And more importantly, could go into a thesis.

And that means that all my work so far isn't wasted. The stuff that I learned about this effect, even the stuff I learned about gyroscopes (because depending on the answer to our question, maybe some of those problems I mentioned can be gotten around someday), can still go into my thesis. These things are supposed to be about 200 pages long, but most of that is usually background material. I was worried that all the background I'd been learning was going to turn out to be totally irrelevant, that'd I'd have to start from scratch. So I am incredibly relieved to be given a new problem that is actually related to the work I've already done.

Now actually doing the experiment is going to be hard, don't get me wrong. I don't know where I'm going to find the time, considering that the trap is going to continue to be a two person job, and there are only three of us in the lab. And I've still got classes to take... And I'm already forseeing a million problems with trying to set this new experiment up, and the problems that you forsee aren't ever the bad ones, either.

But those frustrations are for later. Right now, I'm just relieved to have a new project that won't require me to start from scratch.