Physics

Power Adventures In Iraq

Friday, December 12, 2014 

Plugging things in here is always an adventure. Most of the outlets are the horrible giant British style so they have interlocked grounds, but most appliances are European style, so plugging things in means either using something to jam open the ground interlock, breaking the interlock tabs with force, or dispensing with the plug entirely and just stuffing bare wires in the holes.

When using the latter method, it turns out the British plugs are actually kind of useful because toggling the ground tab with a screwdriver uses the interlocks to bind the wires in place.  You just hope the ground pin is wired to ground, not hot.  Usually it just isn’t wired to anything.

Most appliances and power strips here come from China and are the sort of manufacture China was famous in the US for about 30 years ago: taking something out of the package usually breaks it.  The wires inside are so thin it is amazing they survive and grounds are never, ever actually connected.  I have cables that on the inside have a ground insulator but no ground conductor inside the insulator.  Awesome!

But we just rewired the new villa and even though the ground isn’t wired (of course), the outlets are new and seem like they’re decent quality.  And we even got British style plugs to dispense with the highly problematic and very melt-prone plug adapters.  All seemed good until….

Uh oh.  Maybe it just needed to create a little vent….

outlet_going

 

Nope.  Melt down.  Good thing these have a built-in fuse…  (which is still fine, though encrusted in melted plastic).

outlet_gone

Posted at 15:27:24 GMT-0700

Category: phototechnologytravel

Superconducter B-Field Locking

Wednesday, October 19, 2011 

[youtube]http://www.youtube.com/watch?v=Ws6AAhTw7RA[/youtube]

This is super cool.  It is very tempting to imagine magnetic field lines as being  physical wires, the superconductor being a semi-permeable substance through which the mathematical wires can be forced, but not so heavy as to drag itself through them, even flying around the track.

Posted at 03:02:03 GMT-0700

Category: technologyvideo

C+?

Thursday, September 22, 2011 

There’s been an interesting newskkake and premature twittergasm of commentary on the pre-publication announcement of results from an experiment at CERN that suggest that neutrinos traveled from CERN to Italy faster than the speed of light.

The announcement reminds me a bit of absolutely unbreakable quantum cryptographic key distribution where the theory was strong but weaknesses in any real detector make Eve’s job easier than theory would suggest.

As the CERN paper was published in the last few hours atarxiv.org none of the reporters who’s breathless reports are generating so many tweets actually read the paper they are reporting on. Remember what happened when UT issued a press release before the paper was peer reviewed.

The conclusion of the paper is that the experimenters measured a time of flight discrepancy of 60.7 +/- 14.3ns or 0.00248% +/-.00058% [(v-c)/c%]. If one reads the paper, the complexity of measuring time of flight over 730km to a nanosecond or two isn’t trivial and there’s a huge number of very complicated (but very accurate) measurements between Switzerland and Italy that go into computing this result, it isn’t like you can just call up and fire a neutrino and say “let me know when you see it.”

The CERN measurement isn’t that far off the 2007 MINOS measurement of 0.0051% +/- .0029% (v-c)/c%. The MINOS experiment wasn’t hyped, but it does tend to validate the CERN experiments (or, more accurately, vice versa).Opera_C_plus.jpg

It is important to remember that the six sigma of the 10x more accurate CERN measurement (than MINOS) is about 2 parts per billion, not far off the odds of winning a multi-state lottery. That is, chances are 50/50 that if you had 500 million researchers testing fundamental constants to equal accuracy, you’d get an anomalous result like this overturning some branch of physics every publication cycle that would turn out to be erroneous. And this is why scientists don’t start rewriting textbooks on the first anomalous result, even if breathless journalists try to.

Further, it is also important to note that the researchers do not speculate that the neutrinos are actually traveling faster than light in violation of general relativity, even if the experiments can be repeated, rather that Leonard has created a little more work for Sheldon. Both “traditional” relativistic phenomenon and poly-dimensional theories (like string theory) provide a theoretical framework whereby in our observation frame an object moving in a different reference frame might appear to be moving faster than the speed of light in our reference frame, for example, perhaps neutrinos interacting oddly with gravitational time dilation. Or, maybe, just maybe, there’s room in the universe for a 0.0051% error: good enough for government work. Or maybe, as Newtonian mechanics described life at human velocities accurately but failed to describe relativistic phenomenon, so too relativity may not be a complete description of the universe.

http://en.wikipedia.org/wiki/Faster-than-light

Posted at 21:34:23 GMT-0700

Category: technologyTwitter

Italy at Night

Friday, July 8, 2011 

I was playing with long exposures with the NEX5. I got a cool picture with a shooting star in the background – it wasn’t visible to the naked eye, but showed up on the image (almost typed “film”). It was a 30 second exposure at ISO 6400, very cool that it resolved the color of the trees and tower by starlight.

The village was is an automatic HDR composition which reports 3.2 seconds at ISO 1600.

DSC04540.JPG

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Posted at 17:32:25 GMT-0700

Category: photoplacestravel

Visiting Radioactive Chernobyl

Tuesday, June 21, 2011 

Carolyn and I visited the Chernobyl reactor site with a Singularity University reunion organized by Andrew Bain (who did an amazing job, BTW, thanks!).

We had a walk to the crippled facility, the visitors center (in the shadow of the west wall of the crippled reactor), and a walk around the town of Pripyat made famous by Elena.

Chernobyl seems a particularly relevant lesson in light of the hysteria over radiation reaching the US from Fukushima. It has been 25 years since the reactor accident at Chernobyl and it is a good test of what will happen in Japan.

In Fukishima the reactor cores melted and cooling water carried radioactive material into the ocean, while there were gaseous emissions of hot materials, including (apparently) some radio isotope emissions. There were a few explosions, but of hydrogen liberated by thermal reaction – that is chemical explosions (not a “hydrogen bomb” as in an explosive fusion reaction). When Chernobyl’s reactor 4 blew up, the core blew open and the 2,000 ton upper plate launched 30 meters in the air, through the roof of the containment building, to crash down 90 degrees rotated into the core base. Without coolant, the core itself vaporized (kind of a fizzle yield bomb, about 3 tons of TNT) which blew almost all of the fuel into the air to disperse over the countryside, mostly into Belarus.

We measured radiation levels on the site as we went:

  • 0.14 µSv/h in Kiev (granite buildings).
  • 0.10 µSv/h at the 30km exclusion zone
  • 0.10 µSv/h at the 10km exclusion zone
  • 0.66 µSv/h at the south fence line of the reactor
  • 3.41 µSv/h at the monument in front of the west wall of the containment
  • 7.04 µSv/h in some dirt at the abandoned amusement park
  • 16.07 µSv/h in the car driving over the plume – that was the only place where it seemed as trees hadn’t returned immediately.

According to XKCD, a NY-LA flight = 5 hrs = 40µSV = 8µSv/h.

Thank you Luca, for the picture

Working at the visitors center, right next to the destroyed reactor, results in an exposure rate less than half that a flight attendant gets. Not that it would be smart to dig around (the contaminated dust from the explosion is estimated to be buried about 10cm by now), nor would I suggest eating the local produce, but walking around one needs only minor precautions such as long pants and closed shoes as beta emissions are highest at ground level and are significantly absorbed by the air before getting to head level. The ground we walked on had been cleaned, radioactivity levels were higher in the woods and other areas that hadn’t been scrubbed and stripped, but by now are no longer particularly dangerous.

25 years after the explosion there is a lot of activity on the site and on a nice summer day, we were told, 1,000 tourists might visit. We were one of three small groups when we were there, a bit early in the season, and at 8, the largest.

The site itself has become very beautiful, pretty woods with lots of birds and apparently moose and other large animals roaming around more or less happily free of people. The degree to which the surrounding forest has overtaken the abandoned town of Pripyat is quite amazing and shows the transience of human construction. Like every tour group, we visited the iconic school and amusement park, which are particularly poignant.

On the way out, we had to pass through a tourniquet (or turnstile in alternate translation) with radiation detectors. We were told that if we were contaminated we would have to try to clean up to get a passing score and anything that couldn’t pass had to remain. Nobody set off any alarms.

Lots of pictures below:
Posted at 23:39:46 GMT-0700

Category: photoplacestechnologytravel

HDR video with SLRs

Friday, September 10, 2010 

HDR is kind of cool – a nice way to get past the limitations of solid-state image sensors and recover some of the latitude of film, even improving on it.

The problem is that solid state image sensors tend to have very linear responses to light – an underexposed image vanishes into the noise floor of the sensor while an overexposed image clips off to pure white.  Film exposure response is commonly called an “s-curve” and basically means there’s some data in the random conversion of a light sensitive molecule here or there even in the most underexposed image, and a few that resist converting under the harshest blast of light such that there is perceivable data in both.

This film is a pretty impressive example of HDR video.  But there’s something a bit odd about such a technical achievement in cinematography mixing up “underexposed” and “overexposed.” The funny thing is, they’re using the terms as in making a print (e.g. printing on photo paper) or an x-ray where more light darkens the print: the paper starts out white and turns black with more light vs. a film or digital exposure where the media yields a black result that increases in representational lightness with with increasing light exposure.

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Posted at 00:51:58 GMT-0700

Category: filmstechnologyvideo