Monthly Archives: August 2010
Politics and the Star Trek Effect
There are a couple of episodes of Star Trek that I can recall having some fundamental physics failures, which would lead one to believe that in the Star Trek universe, one cannot do an integral over time. The episodes that come to mind (and it’s been a while, so I may have some details wrong) are The Paradise Syndrome from ToS, and Déjà Q fom TNG. In both episodes, the Enterprise needs to transfer some energy and momentum to an object, and in each episode, they go for the Big Effort™ and lose.
In The Paradise Syndrome, Spock tries to deflect a large asteroid and fails to budge it, so he goes for broke and zaps it so hard he burns out a whole bunch of circuitry — the sci-fi equivalent of overexerting one’s self and pulling a muscle — and can subsequently only match the speed of the asteroid. It’s after this that we learn that the asteroid is two months away from the planet; a force exerted continuously for two months would transfer half a million times more momentum than their ten-second attempt, so they could have even tried a smaller force for that duration and deflected the asteroid. But that makes for boring TV. (And they could have increased their speed my throwing junk out of the rear shuttle bay, with bonus points if the projectile hit the asteroid, since the collision would slow it down. This would have been slightly more exciting than two months of pushing, but still not very much excitement) Similarly, the attempts to restore a moon’s orbit is made in fits and starts in Déjà Q, though in the plot there is at least an excuse for interruptions to their attempts, from some attacking Calamarains, but that’s after they gave up a few times. Forces cause accelerations and change momentum of an object. With the exception of the static frictional force on a surface, these don’t turn on and off only when a threshold is reached*.
\(p = int F dt\)
For a constant force this is just p = Ft. Linear in force, but also linear in time.
What’s the connection to politics? The US government seems to approach solutions to problems like the Star Trek folks do. Wait until the problem is a crisis and then try and exert a huge force to correct it, when a much gentler push would have sufficed if you had simply started earlier. We have been seeing this with Social Security for decades now — we know the system is going to go broke, and yet nothing is being done to fix it. Had we started when I first started paying into the system, the adjustments could have been relatively small. But like the transfer of momentum, the longer we wait, the force needed to achieve the desired result gets larger. The occasional nudge does only a little; it needs to be sustained.
Similarly for global warming. Our government hems and haws and does very little to actually address the problem. Even those politicians who are still doubtful (or whose palms are being greased so that they act doubtful) should be able to recognize that there is value in weaning our country from foreign energy sources, and that the kind of technology adoption involved takes decades to realize.
Of course, getting them to do something would be asking them to do their job, and we can’t have that, can we? Star Trek ignored physics because slow-and-steady makes for little drama, and TV, like sex, is all about having a climactic ending. Our elected officials have no such excuse. They are distracted by the manufactured controversy du jour, and are more concerned with not upsetting their benefactors and voter base than doing the business that’s in the best long-term interest of the country.
*which really isn’t how the frictional force behaves, but it’s a reasonable first-order approximation for its highly nonlinear behavior
Entanglement Done Right
I finally found post about quantum entanglement that does a great job of explaining entanglement, in the context of an attempt to entangle macroscopic objects: Spooky Mirror Tricks. As far as I have seen, it contains none of the “wall of shame statements” I ranted about recently. Quite the opposite.
[Entanglement] allows two particles to form a quantum object even when they are far apart.
…
[I]f one measures, on one particle, the quantum property through which that particle is entangled with other particles, the same property will promptly be determined for each of the particles involved.
…
[E]ntangled quantum particles behave similarly: there seems to be a strange connection between them. However, even this image is misleading, as there are no physical forces in play. In addition, only certain properties are ever entangled. For light quanta, for instance, this can be what is known as polarization, which can be imagined as a small pointer.If two entangled photons are prepared in a certain way, then the polarizations of both photons must point in exactly the same direction.Now, although the two photons must obey this strict “principle of conservation,” the quantum world does not dictate the direction in which the polarizations must point in relation to their surroundings. This is a further quirk of the entangled quantum world: as long as a property isn’t measured, it isn’t fixed for the object being observed. Only when someone measures the polarization of one of the two photons does he give it a direction relative to its surroundings. The polarization of the other photon must then immediately point in the same direction, no matter how far away it is.
Voilà! It can be done! Hear ye, hear ye. Let the journalism world know that you can explain entanglement properly, without mentioning Star Trek at all.
The Tipping Point
There’s a neat effect just after the 2:00 point of this video: the pilot does a barrel-roll, and the beverage in his cup does not spill. Then, he pours iced tea into his cup while doing the maneuver. The beverage in the cup remains pretty much parallel to the support the whole time.
The physics here is the same as with a swinging bucket; one must realize that the plane isn’t simply rotating along its axis — it’s following a circular path, and there is always lift (i.e. a force) going from the bottom of the plane to the top. I recreated this (to an extent) with a clear container and some Romulan Ale (I only use it for medicinal purposes). The first frame is where I was holding the bottle, so it’s at rest. The liquid is clearly at an angle to the container, and is parallel with the floor.
And the second is while the bottle is a freely swinging pendulum, and you can see the liquid is now level with the bottom of the container.
Blah, blah, blah. Oh, balls. I was working on this a while ago and now find that Rhett has a post up about it, though not following the same path I was going to take. Pouring tea in a plane – upside down, where he’s worked out all of the physics, with diagrams and pictures with circles and arrows and a paragraph under each one explaining what it is. So I’ve abandoned my v/2 (half-fast) explanation in favor of a link to his.
Guns, Germs and Steel: Short Version
World population by latitude and longitude
Map appears if you hover over the graphs
(title idea shamelessly stolen sincerely flattered)
A Matter of Perspective
Mindset List for the Class of 2014
The class of 2014 has never found Korean-made cars unusual on the Interstate and five hundred cable channels, of which they will watch a handful, have always been the norm. Since “digital” has always been in the cultural DNA, they’ve never written in cursive and with cell phones to tell them the time, there is no need for a wrist watch. Dirty Harry (who’s that?) is to them a great Hollywood director. The America they have inherited is one of soaring American trade and budget deficits; Russia has presumably never aimed nukes at the United States and China has always posed an economic threat.
…
– John McEnroe has never played professional tennis.
– Clint Eastwood is better known as a sensitive director than as Dirty Harry.
– They never twisted the coiled handset wire aimlessly around their wrists while chatting on the phone.
– Woody Allen, whose heart has wanted what it wanted, has always been with Soon-Yi Previn.
… gettin’ old …
What's Eating You?
A Lecture On The Psychology of Animals Swallowed Alive
From 1925
[Darwin] states that big sharks swallow the porcupine. fish, and has frequently found it floating alive and distended in the stomach of a shark. On one occasion a porcupine fish swallowed by a shark had eaten its way out, not only through the coats of the stomach, but through the walls of tlhe body, and thus destroyed its captor.
Darwin asks, Who would ever have imaginied that a little soft fish could have destroyed the great and savage shark? The diodon iniflates itself with air and water, which it expels with some force when it deflates. The jets of water must cause some curious ticklings to a shark with a lively diodoni in its stomach!
Turning, Turning, Turning Through the Years
Physicists say cosmic rays affect the length of day
I’d like to add a warning to this (along the lines of the Journalism Warning Labels by Tom Scott): Article title implies much more certainty than the article; the article is more restrained than the title would indicate, and the paper (at least the abstract) even more so. Changing the angular momentum of the earth would affect the moment of inertia, but the correlation here is with the sunspot cycle — the connection to cosmic rays is more tenuous.
The abstract actually says
We conclude that variations in mean zonal winds are modulated by the solar activity cycle through variations in irradiance, solar wind or cosmic ray intensity.
I’ll have to consult my local experts on earth rotation and get their opinion on this.
Overheard in the Hallway of the Day
I may be posting more “overheard” stories in the near future; we’re in the phase where we’re assembling all of the parts we’ve been working on, more or less individually, so there’s a lot of team activity, which leads to a lot of chatter. Working alone leads to chatter, too, but that’s more cursing Microsoft or muttering about my own mistakes, usually in that order.
I had rearranged the power cords to segregate the modular ones which plug into equipment (i.e. NEMA M at one end, IEC F at the other) and the ones with exposed wires you could wire into a homemade box (or replace a permanent cord) and mentioned this in the hallway. One colleague termed those “power cords of death,” at which point another went all knifey-spooney, “That’s not a cord of death!”
From his lab:
Power cord of death: a power cord with prongs (i.e. male connectors) on both ends. It was apparently used to daisy-chain power strips together, where one had a bad cord on it. Since they’re just wired up in series, you can do this, but you run the risk of wiring a hot receptacle to another hot receptacle, at which point you might have fried grad student. And they don’t often smell good before frying, so that’s a bad thing™.
Son of power cord of death: this was a power cord, sans grounding plug (snipped off), wired into a cable with a BNC connector at the far end. Used to power a fan acting as a chopper in a vacuum system, and the only available vacuum feed-through was BNC. Proving the old adage that when all you have is a BNC feedthrough, all of your electrical problems look coaxial. (Also proving that most professors won’t spend money on new equipment if the old equipment can be kludged together to do the job)
Turning Japanese
I want a doctor to take your picture
So I can look at you from inside as well
Coloured X-Rays of Flowers : Turning X-Ray Into An Art by Hugh Turvey