The Test(ing) of Time: The Surprisingly Good Hourglass
[The results are] better than I expect for cheap plastic timers that sell for less than $1 each– the uncertainty in the time is about 0.3% of the time, which is pretty darn good. But it’s actually much more interesting than that, if you dig into the data a little.
(Which reminds me I have a half-written timing post that somebody needs to finish)
Is It Time to Overhaul the Calendar?
Their proposed calendar overhaul — largely unprecedented in the 430 years since Pope Gregory XIII instituted the Gregorian calendar we still use today — would divvy out months and weeks so that every calendar date would always fall on the same day of the week. Christmas, for example, would forever come on a Sunday.
“The calendar I’m advocating isn’t nearly as accurate” as the Gregorian calendar, said Richard Henry, an astrophysicist at Johns Hopkins who has been pushing for calendar reform for years. “But it’s far more convenient.”
In keeping with Betteridge’s law, I think the answer is “no”. The objections noted at the end are enough, but inertia is probably enough. The US can’t even get the metric system in place, and there’s a strong passive-aggressive streak of opposing changes that the government tries to instigate. This is also something that a majority of the world would have to adopt, in order to force everyone to do so. I think you need more than streamlining calendar printing/software.
On neutrinos and nanoseconds: Physicists partner with professional timekeeper
In his job, Matsakis keeps the official time for the United States and the U.S. Department of Defense and, together with the National Institute of Standards and Technology, keeps the official time for the United States. This involves maintaining more than 100 atomic clocks and GPS systems calibrated to within one nanosecond of each other – not a simple task.
We had a nice seminar on what MINOS does and neutrino oscillations recently, as we kicked off this collaboration.
Today is 11/11/11, which is what I like to call line-segment day (or possibly numeral integrity day*) but which is also Veteran’s day in the US (it can be two things!). Here’s a page displaying time from the USNO master clock in the various US/North American timezones; it’s in YY/MM/DD format (though you can’t determine that today) and also has the master clock UTC output so you can observe the further alignments of 11:11:11, in case that’s your bag, baby.
*no crooked numbers
Why Daylight Saving Time Should Be Abolished
I’m not at all opposed to this; I have an increasingly hard time dealing with the time change — especially in the spring. And the argument about saving energy (in the US) seems to have gone by the wayside with more widespread adoption of air conditioning. I do enjoy the extra evening hour of sunlight in the spring and fall because it extends the time I can go geocaching, but I’d manage if we eliminated the practice.
A clock display, anyway. No, it’s not really practical.
There’s one main reason I don’t care how many non-experts rail against topics like we see with global warming or evolution. It’s because they are NOT EXPERTS. When you get into the details, science is subtle and tricky, and even though you might understand the big chunks, there comes a point where the non-expert — even a very intelligent one — will be out of his or her depth.
I offer up an example from the brouhaha of the month, the neutrino experiment. (I trust I don’t have to say no, not that one, the other one.) Followup: FTL neutrinos explained? Not so fast, folks.
There are two issues here. One is the paper itself on which Phil is commenting; the author seems to assume that the GPS satellite use for synchronization is always traveling in the same direction as it passes over the experiment, which I don’t think is the case. But I’m not a GPS expert. The second is that if this purported timing offset weren’t already accounted for in GPS receivers, it would show up as a positioning error. 1 nanosecond is 1 foot, roughly. (3 ns is a meter). So from just this one source we’re talking 10 – 11 meters of error. GPS does better than that. It’s kind of silly to assume that this wouldn’t be accounted for in setting up the system. So my initial reaction is that it’s bunk.
The second part is what Phil posts
I had thought of something like this as well. CERN and OPERA are at different latitudes, and since the Earth rotates, they are moving around the Earth’s axis at different speeds. Could that be it? I did the math, and the answer is no. Too bad; it would’ve been fun to be the person to have figured this out!
As I’ve mentioned at least once before, the rotation of the earth has no effect on clocks. The rotation causes deformation of the earth (we are oblate spheroid, mighty mighty oblate spheroid) and it turns out that the slowing from the kinematic time dilation is offset by a speedup cause by being slightly higher in the gravity well. So on the geoid, clocks all run at the same rate, and you only have to account for elevation changes.
It’s not surprising that an astronomer wouldn’t know that. Hell, I didn’t know that for the first few years I worked with clocks, and when I asked the question, the people I talked to weren’t sure why latitude corrections weren’t necessary. I went and found the answer in Neil Ashby’s “Relativity in the Global Positioning System”
Considering clocks at two different latitudes, the one further north will be closer to the earth’s center because of the flattening – it will therefore be more redshifted. However, it is also closer to the axis of rotation, and going more slowly, so it suffers less second-order Doppler shift. The earth’s oblateness gives rise to an important quadrupole correction. This combination of effects cancels exactly on the reference surface.
What does all this mean? Smart people outside of their field will not be familiar with subtle but very important effects. They may, as happened here, raise what seem to be legitimate objections that are well-know to people who actually work in the field.
Neutrinos Travel Faster Than Light, According to One Experiment
I chose this particular link because of the headline, specifically the addendum According to One Experiment. If it’s not reproducible, then it will go down in the annals of science as a fluke measurement.
[T]he result would be so revolutionary that it’s sure to be met with skepticism all over the world. “I suspect that the bulk of the scientific community will not take this as a definitive result unless it can be reproduced by at least one and preferably several experiments,” says V. Alan Kostelecky, a theorist at Indiana University, Bloomington. He adds, however, “I’d be delighted if it were true.”
It’s important to note that the experimenters are not claiming to have overturned relativity and are calling for independent confirmation. If you read otherwise, that’s the journalists or editors trying to show some scientific cleavage.
Another reason I chose this article was that they mentioned how the timing was done, because that’s a likely candidate for introducing error.
Jung, who is spokesperson for a similar experiment in Japan called T2K, says the tricky part is accurately measuring the time between when the neutrinos are born by slamming a burst of protons into a solid target and when they actually reach the detector. That timing relies on the global positioning system, and the GPS measurements can have uncertainties of tens of nanoseconds. “I would be very interested in how they got a 10-nanosecond uncertainty, because from the systematics of GPS and the electronics, I think that’s a very hard number to get.”
Some other commentary: This Extraordinary Claim Requires Extraordinary Evidence!
Update: Here is the CERN press release
Given the potential far-reaching consequences of such a result, independent measurements are needed before the effect can either be refuted or firmly established. This is why the OPERA collaboration has decided to open the result to broader scrutiny. The collaboration’s result is available on the preprint server arxiv.org: http://arxiv.org/abs/1109.4897
Ruth Belville sold time. Each day she would set her watch by the Greenwich clock in London and then charge a fee for the privilege of looking at her watch.
Add “time” to that list of socialist things that people take for granted.
Schriever plans to float-in new master clock system
I don’t always get to talk about details of work, but when it’s been cleared by someone in public affairs, then it’s “out there” and I get to link to it. This is an article about the backup clock facility in Colorado (also the GPS headquarters), which will be taking delivery of its first fountain clock in the near future. There’s a picture that explains how the fountain works that I drew up some time ago (and was improved upon by local peer review)
Though the newer fountain clock provides a stable signal, the equipment itself is very fragile.
“In order to get the Rubidium Fountain Clock into the master clock room at Schriever, the clock has to be floated, like a hovercraft, on a series of plastic mats until it reaches its destination,” Mr. Skinner said. “That prevents the bumping or jarring that might damage the equipment. Since it’s built in-house (at USNO) it would be hard to fix. You can’t just open a catalogue and order a new part.”
The “hovercraft” is, of course, the air sled I demoed a while back.
