Can LIGO Detect Daylight Savings Time? | Hacker News Reader

Can LIGO Detect Daylight Savings Time?

arxiv.org

36 pointszdw12 comments

I was tasked with adding daylight savings (and time-zone) support to an internal monitoring system.

At first I grumbled mightily because I couldn't see the point to it, but after I'd plumbed everything through, I could definitely see the data points snapping in and out of alignment when turning on and off the DST adjustment.

Assume a "moderate" ~45° slope or sine wave... typical diurnal traffic pattern. When shifting by 1hr, that's either 1/24 or 1/12 (call it 5-10%) of "deferred peak traffic"... definitely detectable even with moderate sensitivity.

DST support gave us back confidence in alerting over an abnormally large time range too! Most alerts were set up with a 10-week lookback, discarding both the highest and lowest weeks, so DST changes twice per year potentially threw off alerting for up to 4 months!

I have no doubt that I could detect DST with damn near anything, let alone some crazy calibrated laser inferometer machine!

Can anyone explain in simple terms what is going on here? Author states he's going to "discuss possible causes for this behavior and implications" but I don't really see where it's discussed.

Why would human activity impact the probability of LIGO event detection? Is this because LIGO operators are doing certain things to the detector during their work hours, or some other property of the environment around the 2 LIGO detectors?

The paper mentions that some of it is because of when maintenance is scheduled and when operators are onsite to keep it working. But IIRC they're just incredibly sensitive to motion and any motion (like a truck driving past) affects them.

As I read it basically the detectors get a lot of noise from the environment and humans being active. Driving to work, doing construction, whatever. It detects the waves better when everyone is asleep. Given this information, it's possible to see a shift in detections when the time changes.

Then why is't the paper called "LIGO detection probability is affected by daylight savings time"? Cute titles considered harmful.

Harmful to who exactly?

LIGO has to filter out loads of noise to look for signals. The interferometers are sensitive enough to pick up human activity, like cars, the trains that run over and around Lake Pontchartrain and the Livingston area, and even river flow fluctuations in the Yakima River. Daylight savings transitions basically shift a lot of human activity around by an hour, which can muck with the filtering

Interesting that author (whom I know) is part of LIGO but wrote this paper separately. Probably because it's a fun thing and it would have taken an inordinately long time to get collaboration approval.

The last line about "simplifying approximations within the literature[...] applied outside of their intended context" makes me think the author has an issue with the way other theoreticians are using LIGO data in their analyses.

Months and years from now, pop science outlets are going to use this to explain why most binary black holes collide on Wednesday nights. I can almost see the YouTube video titles now. (-:

reminds me of Large Hadron Collider having beam drift correlated with the Moon

that's what you get at the extreme precision installations - you can measure all the people around

what a useless paper

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