Category Archives: Physics

Practical, but not Practical

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The practical joke arms race of Caltech, MIT and … UBC? Extreme Engineering

In this arms race, UBC is the third superpower. One of its most sophisticated feats also took place on the Lions Gate Bridge, in 1988. Electrical engineer Johan Thornton, now a contract engineer in his late 30s, decided that he wanted to make the bridge lights —all of them—blink. Thornton will only broadly describe the hack, but he hints that the low current of the bridge’s daylight sensor was crucial. For hours, people assumed that the blinking bridge lights were broken. Then the crew of a passing cargo ship reported that the pattern was Morse code: “UBC engineers do it again.”

I had no idea. I spent two and a half years at TRIUMF, on the edge of the UBC campus, but don’t recall hearing about any adventures in my time there.

Teleport, Shmeleport

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Today’s xkcd is about quantum teleportation, but the problem isn’t that journalists write the “same disappointed story” whenever quantum teleportation is being reported. It’s that they still report that teleportation is somehow connected to moving matter around, whether they’ve been waved off about it or not; the latter would be because they didn’t vet their story. They are almost Pavlovian (does that name ring a bell?) in their need to include the reference to Star Trek.

That’s only a small deduction in judging the overall message, though. (Especially the title tag, where Randall zings the sensationalization of story titles)

Playing Hard to Get

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Giving your new results away too soon

[W]here do you announce your results first: in the title? In the abstract? In the introduction? Or, in the results paragraph? If you wait to long your paper will become a whodunit and readers will get bored and stop reading your paper. If the clue of your paper is already in the title you might fear that many of your readers will only read your title and will then go on to read the next paper.

It depends on the type of paper, but I think you generally give your main result in the abstract. The paper gives the details of how you did it, context and information about other related research (but not in that order)

Life is a Cabernet, Old Chum

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Using NMR to check the fitness of wines (Don’t bother with this, for multiple reasons, if they have a bottlecap instead of a cork)

Nuclear Magnetic Resonance Spectroscopy Makes Sure Wine is Fit For the Queen of England

When wine hits 1.4 grams of acetic acid per liter it is considered bad. Although the average bottle of vinegar has around 12.50 grams acetic acid per liter the difference is nothing to take lightly. NMR measures acetic acid in wine down to the tenth of a gram.

Up to 10 percent of wine spoilage comes from the oxygen-alcohol blend. Cork taint, from the 2, 4, 6-tricloroanisol molecule accounts for the other main contributor of wine spoilage. Though NMR is only used in locating oxidation based spoilage, it is still a major breakthrough in the wine world, especially when it comes to auctions.

Auctioneers say as many as 50 percent of the vintages pre-1950 auctioned at places like Christie’s or Zachy’s, where $2000 bottles are the norm, are spoiled. Augustine says that when it comes to exquisite wine the importance of protecting the investment is up to an individual.

And Tyler Colman asks, “Why use a cork in the first place?” when dealing with wines that are a little lower in cost.

Drink Outside the Box

Although some sommeliers may scoff at wine from a plastic spigot, boxes are perfect for table wines that don’t need to age, which is to say, all but a relative handful of the top wines from around the world. What’s more, boxed wine is superior to glass bottle storage in resolving that age-old problem of not being able to finish a bottle in one sitting. Once open, a box preserves wine for about four weeks compared with only a day or two for a bottle. Boxed wine may be short on charm, but it is long on practicality.

Mythological Physics

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Cryptophysicists

One major difference between cryptophysicists and cryptozooligists is that the public is generally able to perceive that the latter are outside the mainstream. Everyone knows from daily experience that there probably aren’t yeti or sea monsters hanging around. Modern physics is abstracted enough from everyday lives and intuition, though, that many people, including some journalists, honestly can’t tell when someone’s waaay out there.

I think people are more familiar with mythology than physics, and the results of relativity and quantum mechanics being so downright weird, it’s harder to say what’s possible and what isn’t. Which makes cryptophysics and crackpottery harder to discern from each other, and from established science. Credulous media doesn’t help.

I wonder if things like string theory have made this worse. No, I don’t — I’m sure it has.

Equivalent to Pigs Flying

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Bee explains The Equivalence Principle

That is what Einstein explains in his thought experiment with the elevator. If you are standing in the elevator (that is just a local patch, theoretically infinitesimally small) you can’t tell whether you are pulled down because there is a planet underneath your feet, or because there is a flying pig pulling up the elevator.

He Helps Us Get High

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August 18, 1868. Jules Janssen “invents” helium. (At least, according to principal Skinner. “Curse the man who invented helium! Curse Pierre Jules César Janssen!)

Janssen was observing an eclipse and measured an emission line with a wavelength of 587.49 nm, which didn’t correspond to any known element. Norman Lockyer also observed the line later that year, and as it could not be reproduced in the lab, proposed that it was a new element, which was named after helios, the sun.

Hail to Thee, Blithe Neutron!

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TS2 on Target – view from the LOQ cabin

A brief overview of some neutron history

Since it carries no charge, one could not “weigh” a neutron directly in a mass spectrometer, but had to estimate its mass from the difference between deuterium and hydrogen. However in 1935, more accurate measurements allowed Chadwick to derive a neutron mass of between 1.0084 and 1.0090 units; the modern estimate lies almost exactly in the middle of this range, and so the neutron is appreciably heavier than the proton. Was Uncle Albert wrong? Chadwick immediately suggested (following Einstein again) that neutrons should have an excess of energy and be beta radioactive in common with other nuclei under like circumstances. It was not so easy, however, to verify this experimentally. But, partly owing to World War II, it was not until 1948 that neutron decay was verified – indeed, 12 minutes after they’ve been kicked out of the nucleus half of them will have split apart as Chadwick had suggested. So if you want to use neutrons, you can’t keep ’em in a bucket.

That last bit is a tad misleading — it’s no doubt referring to the decay, not the ability to confine. Since neutrons have a magnetic moment, they can be trapped. It’s a weird, shallow bucket, and it leaks, but you can keep ’em there until they decay.

It's Not an Inalienable Right!

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Jennifer’s enumeration of the PARTICLE BILL OF RIGHTS reminds me of a neat effect. I hope the second amendment

The right of unstable Particles to decay shall not be infringed.

only applies to militias fundamental particles, because people have been messing with that “right” for a while in atoms. These are demonstrated by some fascinating experiments in cavity QED I read about while I was in grad school. Probably the most familiar cavity QED phenomenon is the Casimir force, which arises from modifying the electromagnetic modes that are allowed to exist. In free space, waves of any and all frequencies and polarizations can exist, but when conducting surfaces are present, these alter the boundary conditions. Two flat conductors, closely spaced, will exclude many mode of electromagnetic oscillation, and because each mode carries 1/2 hf of energy even when there are no photons in that mode, this exclusion gives rise to the attractive force.

But there’s more fun to be had with this.

Imagine placing an atom inside a cavity under circumstances similar to where the Casimir force could be observed. You can prepare the atom in a state so that it can only decay by one mode — one transition, with a particular polarization of photon (either linear or circular), and you can also orient the atom so that the photon’s direction of emission (perpendicular pr parallel to the surface) will correspond to a photon mode that isn’t supported by the cavity configuration. When you do this, what is an atom to do? There is no vacuum fluctuation to induce it to decay, nor would a photon from that decay be able to exist. The atom is forced to sit there, grudgingly (or perhaps happily, I don’t think anyone’s asked) not decaying.

You can also choose your system so that there is a higher mode density, and get atoms to decay more quickly than they would in free space. (You can also repeatedly measure an atom’s state and keep it from decaying, in a phenomenon called the quantum Zeno effect, but I’m not going to go there. Or even halfway there)

So I must conclude that since this action is routinely taken on atoms and molecules, without writ or warrant, and we have declared that we do not torture inhibit decay, that this right does not apply to composite systems.

——

Some references
Heinzen, et.al, Phys Rev Lett. 58 1320 (1987)
Jhe, et. al, Phys Rev. Lett. 58, 666 (1987)
Haroche and Kleppner, Physics Today Jan 1989 24-30

From The Wayback Machine

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From our “Plan of the Week”
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August 12 & 17 1877 – Asaph Hall discovers the moons of Mars. From Halls’ notebooks: I repeated the examination in the early part of the night of [August] 11th, and again found nothing, but trying again some hours later I found a faint object on the following side and a little north of the planet. I had barely time to secure an observation of its position when fog from the River stopped the work. This was at half past two o’clock on the night of the 11th. Cloudy weather intervened for several days.

On 15 August the weather looking more promising, I slept at the Observatory. The sky cleared off with a thunderstorm at 11 o’clock and the search was resumed. The atmosphere however was in a very bad condition and Mars was so blazing and unsteady that nothing could be seen of the object, which we now know was at that time so near the planet as to be invisible.

On August 16 the object was found again on the following side of the planet, and the observations of that night showed that it was moving with the planet, and if a satellite, was near one of its elongations.

Until this time I had said nothing to anyone at the Observatory of my search for a satellite of Mars, but on leaving the observatory after these observations of the 16th, at about three o’clock in the morning, I told my assistant, George Anderson, to whom I had shown the object, that I thought I had discovered a satellite of Mars. I told him also to keep quiet as I did not wish anything said until the matter was beyond doubt.

He said nothing, but the thing was too good to keep and I let it out myself. On 17 August between one and two o’clock, while I was reducing my observations, Professor Newcomb came into my room to eat his lunch and I showed him my measures of the faint object near Mars which proved that it was moving with the planet. On August 17 while waiting and watching for the outer moon, the inner one was discovered. The observations of the 17th and 18th put beyond doubt the character of these objects and the discovery was publicly announced by Admiral Rodgers.
————

This was from a time when the Observatory was located at Foggy Bottom — it was about 16 years later that it was moved to its current location. But the same telescope is still in use.

(And it’s probably a good thing Hall didn’t discover the moons as a university professor, because then the Astronomy building named after him would be Asaph Hall Hall)