Angular transformation of the fedora to JohnB
Category Archives: Links
Happy Birthday, GPS
Solar Sails and Squirrels
Over at the XKCD blag, Randall discusses solar sails and levitating squirrels. And he’s absolutely right — the Back-to-the-Futuresque 1.21 Gigawatts will levitate about a kg, assuming perfect reflection. Assuming absorption, you vaporize the squirrel in a couple of milliseconds.
(1 kg of water requires about 2.5 million Joules to boil away, starting at body temperature. Or not — the latent heat of vaporization is the dominant term)
I think the XKCD cartoons are often quite funny, BTW. A link, if by some odd chance you were unaware of them. I just got a new light box to replace my broken one. Must find time to draw cartoons.
FX
Check out this illusion over at Cognitive Daily, along with all the explanation that goes with it.
I think illusions are pretty neat. They are also a reminder to not trust what you think you are seeing, since our vision is relative and we also see patterns because we impress them on data.
Lycanthropus Interruptus
The entire event is visible from South America and most of North America (on Feb. 20) as well as Western Europe, Africa, and western Asia (on Feb. 21)
Unless your weather sucks, of course.
Snow showers in the morning will give way to a mixture of rain and snow for the afternoon. High near 40F. Winds SW at 5 to 10 mph. Chance of precip 60%. A slushy accumulation of less than one inch.
Mmmmm. Slushy accumulation…
Gazing Into the Relative Past
Came across a great post entitled “The Pre-history of Einstein’s Relativity” over at Skulls in the Stars.
It starts with Galileo and the notions he had to overturn, and progresses through Newton and through to about 1900 1880.
Regarding Newton and relativity,
The first excerpt observes that understandings of space, time and motion that arise from everyday experience lead one to certain ‘prejudices’, or misunderstandings, about the nature of these quantities. In particular, there is a confusion concerning the ideas of ‘absolute’ and ‘relative’ motion. These seem to be the same misconceptions we discussed earlier in the context of Galileo’s work.
Which applies to a whole bunch of physics, especially quantum mechanics, in addition to relativity.
(via Science After Sunclipse)
Added 2-20: next installment, in-depth Newtonian Ralativity
If You Have To Teleport Me, Then I Don't Wanna Go…
Aldebaran’s great, okay,
Algol’s pretty neat,
Betelgeuse’s pretty girls
Will knock you off your feet.
They’ll do anything you like
Real fast and then real slow,
But if you have to take me apart to get me there
Then I don’t want to go.
[Chorus]
Take me apart, take me apart,
What a way to roam
And if you have to take me apart to get me there
I’d rather stay at home.
— Douglas Adams, “The Hitchhiker’s Guide to the Galaxy”
Another recurring theme on the SFN forums is quantum teleportation, along with quantum entanglement. Quantum teleportation is all about sending information, not matter.
Jeff Kimble explains some truths about teleportation
Let's Geek It UP!
Mar 14th is “Talk like a physicist day,” and there’s a blog dedicated to it. Of course, I’ll be doing so anyway, because that’s what I do. My suggestion is to get familiar with some jargon, and substitute it for smaller words whenever and wherever possible. That’s what we do.
(Of course Mar 14th is also Einstein’s birthday and “Pi day” in the US)
Nutating After Dark
Science After Sunclipse has some links to Conan O’Brien spinning his wedding ring and getting help from an MIT professor to maximize the spin time.
(BTW, I have colleagues who use the term “nutate” on a regular basis.)
Trap Some Mercury, Make a Clock (Maybe)
“Trapping of Neutral Mercury Atoms and Prospects for Optical Lattice Clocks” Hachisu et al., PRL, 100(5). I haven’t had time to read the paper, but Chad at Uncertain Principles has a summary of it.
My personal nit is that everybody calls these clocks, and they are really frequency standards/references. But almost nobody cares about that.