Lots and Lots

Physics Buzz: How Much Snow did Washington DC REALLY Get?

Washington DC looks like a 10 x 10 mile square with a bite taken out of it. All together the city is 68.3 square miles. It’s not too hard to figure out the total volume of snow dumped on the city so far.

55.6″ depth of snow x 68.3 square miles roughly equals 8,820,000,000 cubic feet of snow, or 249,000,000 cubic meters. If you were to build a giant cube of snow that big it would be 2,066 feet, or 629 meters on each side. That’s almost two fifths of a mile or two thirds of a kilometer per side. That’s the volume of about 238 Empire State Buildings. That’s a lot of snow.

It's Easy When Someone Else Does It

Starts With a Bang: A Brief History of Time… in the New World!

It was only about a week before people noticed that the Sun and Moon weren’t rising and setting at the times they were supposed to! Apparently, the clock was running at the wrong speed, and was running slow by somewhere around a minute per day. This brilliant clock, which was accurate to within two seconds a day in Holland, must have broken somehow during the journey.

So what were the colonists to do? There was no clockmaker (or clock repairman) in the new world, and this clock was handmade and very valuable. They had no choice; the clock needed to be shipped back to Europe for repair.

So they ship the clock back to Europe, and they go to take the clock into the clockmaker, and it does the exact thing that your car does when you take it to the mechanic because it’s making a noise. It starts behaving like it’s perfectly fine. The clockmaker winds up the clock, and it immediately starts working properly, and keeps time to within two seconds per day!

The needed to appreciate the gravity of the situation, of course.

A very nice story, up until the last sentence:

So go ahead and take your standardized time for granted, but remember that it wasn’t always as easy as it is today!

Easy for whom? The dragons currently live at several picoseconds per day instead of several seconds per day. Scientists doing research are always trying to be on the part of the map that says “Here be dragons.”

The Demon's in the Details

Uncertain Principles: Entanglement Happens

(Oops. I accidentally hit publish instead of save yesterday, and didn’t add my comment. Hence the time travel on the post.)

There are several application people try and use entanglement to pull off some neat trick (e.g. clock synchronization) and the problems Chad points out are often glossed over. It’s almost like the famous Sidney Harris cartoon, “Then a miracle occurs,” when the step in the procedure is “we take our entangled particles and move them an arbitrary distance apart,” which ignores the little demons Chad describes, that compromise your ability to know the measurement basis after your system has been exposed to the real world. It’s not quite at the level of ignoring the second law of thermodynamics and proposing a perpetual motion machine, but it’s almost as naive to propose it for an arbitrary system, without working out the details.