Monthly Archives: January 2009

The Photon Push-Me Pull-You Update

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Back in June I wrote up a post an the Abraham-Minkowski controversy, which concerns the momentum of a photon when it’s in a medium.

Depending on the assumptions one makes, one can show that the momentum increases or decreases inside the medium, and obviously both solutions can’t be correct. But for a long time it was unclear which assumptions were faulty, because it was such a delicate experiment to do.

I just ran across a post at Everyday Scientist, and the paper (based on the ArXiv preprint I cite in the link) was published last month … and there’s a video.

Light Bends Glass

The researchers performed a second experiment with a longer fiber and continuous–rather than pulsed–laser light and found similar results. The tip of the hanging fiber moved sideways like a pendulum by about 30 microns, which agreed with the tiny force (less than a billionth of a Newton) that they predicted. The team also verified that thermal effects, such as heat expansion, would be too small to influence the fiber’s movement.

You need to a flashplayer enabled browser to view this YouTube video

We Lost … to Mathematicians?

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Doing the Math to Find the Good Jobs

The study, to be released Tuesday from CareerCast.com, a new job site, evaluates 200 professions to determine the best and worst according to five criteria inherent to every job: environment, income, employment outlook, physical demands and stress.
[…]
According to the study, mathematicians fared best in part because they typically work in favorable conditions — indoors and in places free of toxic fumes or noise — unlike those toward the bottom of the list like sewage-plant operator, painter and bricklayer. They also aren’t expected to do any heavy lifting, crawling or crouching — attributes associated with occupations such as firefighter, auto mechanic and plumber.

Physicist ranks 13th, presumably because we experimentalists get to play with dangerous things, which I consider a perq. At least we beat out Astronomer; I suppose that’s because they have to work nights.

… So I Rewired It …

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Part of every trip home involves attacking the “to-do” list of things my mom can’t take care of by herself. She has several wonderful neighbors who do some more immediate things like plow and shovel her out when it snows (she mows their lawn in nicer weather on her riding mower), but other tasks can wait until one of the children visit. Wrangling the artificial tree from and back to the basement, lugging things to the attic, etc. are normal November/December/January chores.

But there were three bigger jobs. One neighbor has a very large generator that was put to use during the recent ice storm; our street only lost power briefly, but the houses behind us were on the wrong side of a fallen tree and were without power, and he supplied them with enough to run the heat and other basics. To facilitate hookup for the next power outage, he decided to shuffle some breakers in our house so he could backfeed through some outlets in the garage. So I helped a little with that.

The second job was to extend the recently-installed sump pump drain further away from the house; the original placement was on the high-elevation front side of the house, and only about 5′ away. The ground had become saturated and all of the water being dumped was just filtering back in to the basement. So I got to go down to the HO E DEPOT (the “M” was being replaced) and get some PVC pipe and run the drain line off to the side of the house, about 20′ away, and an area that will drain down the hill. There was snow on the ground, so I couldn’t do a proper job and bury the pipe, a task that will have to wait until better weather.

The last job was repairing the ancient pinball machine in the basement game room. It was a relic when we got it, about 35 years ago — relays and gears and a mechanical score display, which had gone out of vogue when digital displays and electronics came out. It hadn’t been looked at since my dad died, some 12 years ago, but hadn’t seen much use for a few years after that, until my nieces got old enough to want to play. By that time my mom had re-done some flooring upstairs and installed the old carpet in the game room, and it was some time later that we noticed that the key that opens the machine was missing, and was probably sitting on the floor, under the carpet and all of the junk laying on top. So, no access to the guts of the machine, until my mom had someone in to drill out the lock this past fall.
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Just Checking

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Possible Abnormality In Fundamental Building Block Of Einstein’s Theory Of Relativity

Physicists at Indiana University have developed a promising new way to identify a possible abnormality in a fundamental building block of Einstein’s theory of relativity known as “Lorentz invariance.” If confirmed, the abnormality would disprove the basic tenet that the laws of physics remain the same for any two objects traveling at a constant speed or rotated relative to one another.
[…]
The new violations change the gravitational properties of objects depending on their motion and composition. Objects on the Earth are always moving differently in different seasons because the Earth revolves around the Sun, so apples could fall faster in some seasons than others. Also, different objects like apples and oranges may fall differently.

I find it amusing that there are a bunch of relativity cranks who claim that relativity is treated as dogma. The reality is that it isn’t all that hard to find scientists devising tests of relativity of various sorts, whether it’s testing the predictions of GR or checking for anomalies such as this.

Of course, thus far whenever someone has devised a clever test like this, we’ve found that relativity is correct.

Beulah, Peel Me a Grape

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And nuke it.

Things to do in a microwave #2: Create a plasma

It just so happens that grapes are about the size of the wavelength of microwaves, which is important. And grapes also have sugars, which make them into dielectrics. (There are other fun things you can do with grapes because of this). Both of those together make the coupled grape halves into a dielectric dipole antenna, which is just a fancy way of saying that the microwaves that hit one side of the cut grape will pass to the other side, in a very concentrated way. The result is that there is a huge voltage generated between the two sides of the cut grape. That voltage causes electricity to jump from one grape half to the other (”arcing”). This is what happens when you rub your socks on the carpet and touch the doorknob — that spark is electricity jumping from your hand to the doorknob. The difference in this case is that there is a HUGE voltage generated (3000 volts by one website), and that is enough to ignite the steam from the grapes into a plasma state (a glowing ionized gas, where the electrons have been ripped from the gas molecules by the high temperatures). You can capture this plasma in a glass, as in the video above (wow!)

And, of course, this is preceded by Things to do in a microwave #1: Find your microwave hot spots

In addition to the two methods Stephanie lists, you can use marshmallows or chocolate chips, and look for where the melting starts. And then you can eat the experiment. (Stephanie mentions marshmallows; I missed it)

Update: Not done yet! Things to do in a microwave #3: Ivory Soap Monster

Things to do in a microwave #3: Microwave a CD
#3? Should be #4. (I’ve brought the whole “Five is right out!” counting thing to Stephanie’s attention) There’s an image that shows some mini Lichtenberg figures, i.e. the little tree-like patterns the electrons make.

Things to do in a microwave #5: Microwave a lightbulb

Maybe They Should Buy a Computer

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Wait, what? Two frikkin’ weeks to process an electronic request to update an automated process? Does this perhaps involve the Gerbil Express and pneumatic tube data transfer system? Are you baking clay tablets for data storage? This should take two microseconds!