Monthly Archives: November 2008
Rube-y Goldberg Tuesday VI
Not a video, but take a look at these drainpipes
Pontiiiiif!
Assembler is a new physics based wonder where you move some depository equipment to get your precious green crate in position. For what? No matter! Physics work perfect and the feel of grabbing and moving around things is just perfect. Don’t play too much or you’ll dream of dirty green crates flying around
It's About Time, Part I
(trying my hand at putting latex into posts. Since the preview function doesn’t work, this may not go well)
I’ve already commented that, within the timing community, optical frequency combs are basically everywhere, and that this is driving a lot of investigation into optical transitions for clocks/frequency standards.
Why are these such a big deal? Let’s start with what we’re measuring. Time, as Albert had put it, is what is measured by a clock. Put another way, in terms of what a clock is doing: time is the phase of an oscillation. To build a clock, you need an oscillator and something to count the oscillations, or fractions thereof, i.e. the phase, in chunks of 2\(pi \) or possibly smaller. If your oscillator is running at some frequency \(omega\), you have
\(phi = omega t \), or put another way, \(omega = frac{dphi}{dt} \) and you integrate the frequency, or count the oscillations, in order to get the phase (time)
That is, the phase (the time you measure) is just the counting of all those oscillations over some period of time. If the frequency is 1 cycle/second, then you are ticking once a second, which is pretty freaking obvious and you’re wondering where you can sign up to get paid a fair wage for something that’s so utterly, blatantly true.
But … what if the frequency isn’t constant? How can you possibly tell what’s going on if your oscillator isn’t running at a constant frequency? How do you even know if your oscillator’s frequency is changing? That’s where the work starts, and one reason this line of work isn’t simply a tautology (the “man with one clock always knowing what time it is” aside). What we want is t, but we’re measuring \(phi \), and now we have to figure out how to get one from the other.
Let’s assume that the frequency of our oscillator is changing linearly, and we’ll call this the drift.
\(D = frac{domega}{dt} \) or, integrating, \(omega = D t \)
But we want the phase, so we have to integrate again
\(phi = omega t + frac{1}{2}D t^2 \)
These look exactly like kinematics equations, which should be no surprise, because we’re doing the same math as something undergoing constant acceleration. You can go to higher order, but really you’d want to just get a better oscillator — in practice you put up with drift if you’ve got a precise clock, or if there is some other reason for it. And none of this discussion accounts for other noise that your oscillator would naturally have (and white noise on an oscillator, integrated, becomes a random walk in phase) which will further complicate your analysis; this and other noise sources that depend on fractional powers of the frequency.
But more in line with this review, how can you tell what your oscillator is doing? You have to compare to another oscillator, and things get even more interesting. I’ll pick up here in the next installment.
I Know the Election's Over …
but there’s this
Mayor In Russia Says He Can See Sarah Palin Showering From His House
Governor Sarah Palin, the Republican Vice Presidential nominee, has said that she can see Russia from her house. Across the Bering Strait in Provideniya Bay sits the town of Provideniya, Russia and its mayor Dimitri Andropov. He says that he can see Palin showering from HIS house. “And it is very nice.”
Typocalypse
Worst Nightmare
Russia: 20 dead from poisoning in sub accident
The fire safety system on a new Russian nuclear-powered submarine malfunctioned on a test run in the Sea of Japan, spewing chemicals that killed at least 20 people and injured 21 others, officials said Sunday.
The majority of the students I taught were destined to serve aboard submarines, and several of the friends I had when I was in the navy were submariners; I have a lot of respect for the job they do. Years ago I spent a day on the Will Rogers, but any insight I have here is primarily from observation rather than direct experience.
Fire, and the repercussions of it, rate pretty highly on the list of things of which submariners are covertly or overtly scared. You have a limited oxygen supply, and cramped spaces making it tough to navigate. So you drill incessantly to make responses (to this and other potential problems) instinctive.
If you’ve ever wondered why folks in the military carry out orders without question, and why the people giving the orders expect you to, this is it. You do as your told because if you don’t people can die. There may not be the time or practicality to explain why or when lives might hang in the balance, or be able to discern it yourself, so it’s best if you operate under the assumption that it’s always the case.
The article raises the possibility that this was human error, and if it was, it shows the awful repercussions of not following procedure or some other kind of scewup.
Canine Cravings
Way back in March I posted a video link (Dog Ballistics) showing a motorized ball launcher, allowing an automated way for a dog to play fetch.
Now, in my tireless scouring of the intertubes (is calling it tubes a felony now?), I find plans to build such a device. Your Dog Wants A FetchBot. It doesn’t have the automatic inclination adjustment, but it still launches.
[T]he cool part is that it’s built mostly out of a cannibalized document scanner. It contains some simple electronics to control the motor, but it’s totally something you could build yourself in an afternoon. C’mon, you can do it! And your dog would love you forever.
My Big Day
Breaking News: I wore a suit at work on Friday. I don’t think I had even worn a tie to work since leaving the navy. (I think most people who work in similar lab situations would agree that fancy clothes tend to interfere with real work getting done.) The party that got me all spiffed up? USNO Dedicates New Master Clock facility (pdf press release) It was actually a dual celebration for a couple of us, since not only were we dedicating the new building, we were acknowledging the delivery of two of our fountain clocks, which were recently moved in, and I worked on both projects.
I started on the building more than four years ago, and I was actually a little late to the party. The original concept dates back to the early 90s, when Senator Byrd proposed a clock facility in West Virginia, but that idea got shot down when Senator Proxmire put it on his “Golden Fleece” list, showing that governmental inability to assess the merit of science and technology is not a new phenomenon. My involvement came after funding was approved and the preliminary design detail was being worked on. I was asked to fill in for someone who was going to be out of town, and was handed a list of changes items under discussion, and a two-inch thick draft of the request for proposals (RFP) that outlined the specs for the building, two days before the meeting. I muddled through that and didn’t embarrass myself at the meeting (but didn’t contribute a whole lot, either), and since the situation was likely to come up again — and it did, several times — I insisted on continuing to attend meetings to stay in the loop. (The draft RFP had obviously been cut-and-pasted from other documents, since the early version included a requirement for the site supervisor to speak fluent Italian, and that all deliveries be coordinated with the harbormaster at Pearl. It was a bit of work getting it straight.)
The preliminary design work involved getting our specs translated from scientist/engineering terminology into architecture and construction-speak. Then the RFP went out, and companies bid on the project. Even though it was apparent that the budget was tight, we were able to find one company that would do it, after some negotiations to trim a few items from the project. The novel nature of the building’s requirements, including
elaborate environmental control system to keep the clocks in strictly regimented temperature and humidity conditions. The building’s temperature will be regulated to +/- 0.1°C and its humidity will be controlled to within a 3% tolerance
Along with some other requirements this meant that this wasn’t just an office building, which was something that had to occasionally be pointed out. But we had a pretty good relationship with the contractors, and despite a few bumps and rough spots, we eventually got it done. It just took more time than we anticipated, both with the scrutiny we had to place on the day-to-day construction, and how long the fine-tuning would take.
Since the pressure and discomfort of such an event wasn’t enough, the mom came down for the ceremony, to add the requisite parental scrutiny. The Vice President made an appearance for a photo-op with the bigwigs. The main speaker for the dedication was the Honorable John G. Grimes, Assistant Secretary of Defense for Networks and Information Integration /Chief Information Officer, with whom I got a chance to speak. I’m not used to rubbing elbows with the top brass like that, but he stuck around quite a while, asking questions and talking with people.
Happily, I’ve now forgotten everything about the details of how to build a building, or the details of our new clock facility, so there is no need for anyone to come to me and ask about it. If someone wants me to weigh in on an issue related to it, I’ll finally get to shrug my shoulders and say, “I dunno.”
Oh, By the Way …
Whoever called a little while back, woke me up and asked me, “Who is this?”
I hope you get your own special circle in Hell. Screw you.
(Phone calls in the middle of the night are invariably bad news. Either a wrong number, or some sort of emergency. Either way you’re jolted awake, with that adrenaline release.)