The brilliant young PhD student Ralph Alpher working with his advisor George Gamow were about to publish a major work about the origins of the elements after the Big Bang. In a burst of inspiration, Gamow invited the physicist Hans Bethe to include his name on the paper, even though he had not contributed to it at all. That way the paper would have been authored by Alpher, Bethe, Gamow, a play on the first three letters of the Greek alphabet alpha, beta, and gamma. It was a delightful pun, and their one page paper serendipitously ran in the April 1st issue of Physical Review Letters.
Category Archives: Physics
Random Laser
The Laser Glow of an Atom Cloud
A normal laser is essentially a gain medium inside a reflective cavity. The light is amplified by the medium as it bounces back and forth between the cavity’s mirrors. A random laser has no cavity. Instead, tiny “mirrors,” or scatterers, are added to the gain medium, causing photons to bounce around and become amplified by the medium, before escaping in all directions. For example, a container of micron-sized particles floating in water in which a laser dye has also been dissolved can emit laser light if pumped with external light. Random lasers do not require the same precise manufacturing as normal lasers, so they could be inexpensive to produce. Potential applications include digital displays, light emitting paints, and temperature sensors.
Not Sunspots
Compton Lecture: Steven Chu
The energy problem and the interplay between basic and applied research
aka The Big Captain Crunch
But Rich Hall snigletified this first: The Cheerio Effect
In fluid mechanics, the cheerio effect is the tendency for small wettable floating objects to attract one another.
[…]
The phenomenon of molecules clumping applies to any (macroscopic) object that floats or clings to the surface of a liquid. This can include a multitude of things, including hair particles in shaving cream and fizzy beer bubbles. The effect is not noticeable in boats and other large floating objects since the force of surface tension is relatively small.
All is not well in Cheerio-land, however. Cheerios might be considered a drug, in a daft legalistic way similar to how tomatoes are a vegetable.
Physics v Chemistry. This Time it's Personal …
Experimental Error: Physics vs Chemistry: Fight!
I often contemplate the differences between these two areas of study. Also, I hear fellow undergrads argue for one or the other, usually divided along the lines of their respective major. Anymore, I think they’re so interrelated that I find it hard to find a difference between the two, except for the phases of matter that they most often deal with.
Same? Different? I think we should forget that, team up, and beat the crap out of biology.
Yakity Yak
Oh, wait. Wrong coasters.
Cocktail Party Physics: a new wrinkle
The Rocket Scientist is the only faculty member I’ve ever known who keeps coasters in his office (and requires their use). I’ll let you figure out what a coaster fetish tells you about RS – I have my own theories, but (ignoring for the moment the fact that we work for a public university and all our furniture is laminate) there actually are really good reasons for one to use coasters.
Trivia: polymethylmethacrylate (PMMA, mentioned in the post) is an electron-beam resist. That is, if you zap it with electrons (or hard UV) you break some bonds, and the exposed material can be removed chemically. Makes it a useful mask material for various lithography applications.
gg the Ghostbuster
Skulls in the Stars: Optics in the Haunted Mansion!
The Haunted Mansion is one of my favorites, with its classic Gothic ghost story atmosphere and dark sense of humor. As a child, I was terrified of the essentially harmless attraction. This trip, as a professor of optics, I was delighted to not only see the clever special effects, but deconstruct them — to “peek behind the curtains”, so to speak.
Aye Arr!
Picked up another light source. My previous broadband purchase was a UV light , and since I was deficient on the other side of the visible spectrum, I grabbed an IR source LED flashlight. I snuck into the lab to measure the spectrum, because we have an analyzer that covers 600-1700 nm. Just popped the flashlight onto the input jack (for fiber) and that coupled enough light in to make a measurement.
Here’s what it looked like:
The early scans were smooth, so I’m not sure if the couple of dips in there are a result of some setting I changed, or if it’s a real effect (perhaps of heating up — the flashlight gets warm after a while, and this is a scan of the output after it was on for a few minutes)
This isn’t the first (nor, I expect, the last) test of something mundane, just because the equipment is available. A few years back there was a rumor that the US $20 bill had an RFID chip in it, located in Andrew Jackson’s eye, as “evidenced” by bills burning at that position when microwaved. A colleague and I tested that with a network analyzer, since an RFID chip should have a strong absorption feature on resonance. Nada. Not surprisingly, it’s an urban legend. (I swear it’s not there. Trust me: I work for the government)