You can get an update
www.hasthelhcdestroyedtheearth.com
Added (9/14): for redundancy there’s also www.hasthelargehadroncolliderdestroyedtheworldyet.com/
Category Archives: Physics
The Gang's All Here
I’m sure you all noticed that in the last panel of today’s XKCD, Randall mentions all of the quarks.
Up, Charm(ing), Strange(r), Top, Bottom, Down.
Geek meter: pegged.
Master of Understatement
We have had an anomaly … we just had a problem with the vehicle on the pad.
This Isn't My Tenth Top-Ten List
Ten things you don’t know about the Earth
Destroying the Earth is hard
[…]
Even giant collisions can’t vaporize the planet. An object roughly the size of Mars impacted the Earth more than 4.5 billion years ago, and the ejected debris formed the Moon (the rest of the collider merged with the Earth). But the Earth wasn’t vaporized. Even smacking a whole planet into another one doesn’t destroy them!
Shape and the Single Photon
When you detect a photon, you can say where, when, and with what frequency it arrived, but before the measurement, these parameters are undefined. The photon’s existence is embodied in a wave function, which gives the probability of measuring the photon at any time, place, and frequency. The wave function for a single photon is usually a “wave packet”–nearly zero everywhere except in a narrow range of space and time. But as long as you don’t detect the photon directly, you can manipulate its wave function into any complicated shape, in theory.
Ph'amazing
Top 10 physics videos (which constitutes a full rebuttal to the “Top 10 Amazing Chemical Reactions” I had linked to earlier, and had only rebutted with a single physics video, which is #5 on the list.)
You’ll also note that two of the so-called chemical reactions are properly classified as being in the physics videos (Meissner effect and breathing helium/sulphur hexafluoride). Ha! Take that, chemistry. You’re down to a top 8! (Without even arguing that floating a boat of air of the sulphur hexafluoride is a physics effect as well)
(Note the flash photography during the musical tesla coil video. Gee, I wonder if that helps?)
via The Great Beyond, which adds two Feynman drumming videos to the list. Wait, that’s twelve! Twelve videos! (A, ha, ha, ha. I love to count science videos!)
Add Grad Student and Shake Well. Ingredients for TA-ing
How to be a good TA over at Built on Facts.
Disclaimer: I never did recitations as a TA in grad school, though I did tutor students (for a whopping 8 bucks an hour). I had just gotten out of the navy, where I had logged somewhere around 2500-3000 classroom teaching hours, so it’s not like I needed to acquire any lecturing skills. I did labs, which involved only a few minutes of lecture time, and then a lot of Q&A. I didn’t want the repetition of six or so recitation sections, and I knew (from being a student and having done undergraduate TA-ing as well) that labs didn’t always go the full three hours. So, does any of my advice or criticism really apply?
But what do my students say in their confidential evaluations? My scores are always pretty high, but the single most common good thing they have to say about me is this:
He speaks English.
Yeah, I got that a lot, too, as a TA. Which just goes to point out that student evaluations more-or-less follow Sturgeon’s law. 90% of them are crap. The student’s judgments are not always objective, nor do they usually give constructive feedback. They can like or dislike you, and give evaluations accordingly, based on criteria other than teaching quality. And that’s what many of them are — statements of whether the student like you, rather than your effectiveness. I remember one teaching evaluation in which the student complained about how I blocked the board some of the time and he couldn’t read it. He sat near the front in the left-hand row (as viewed from the back of the classroom). I’m right-handed and bigger than a breadbox. It’s physically impossible for me to not block part of the board, and the part I will block will affect those on that side of the class a little more. Basic geometry, really. But it didn’t stop the student from whining about it mentioning it.
Stress Makes Them Bi
Birefringent. Not that there’s anything wrong with that.
In my earlier discussion of polarization, I promised some photos of stress-induced birefringence.
If you have a polarizing filter, you can use an LCD as a polarized light source and view birefringent materials using it as a backdrop. Make the screen as white as possible, and rotate the polarizer until it blocks the light. Then place a birefringent material in front of the screen and look through the polarizer. Cheap clear plastic often will have stress-induced birefringence.
Which is what I did, and is why the background is black. The first photo is the plastic box in which the polarizers were packaged
These next two are the side and top views of a styrene drawer from a small storage cabinet, placed on top of an empty CD spindle.
Go Away. But Come Back.
A couple of good physics posts.
Optics basics: Coherence at Skulls in the Stars
Charging the Earth at Built on Facts
Nobody Thought of this Sooner?
Industry’s First Intregrated Triplex Receptacle
Provides three outlets that can accept 3 plugs simultaneously, eliminating the cluttered look of power-strips or necessity for multi-outtlet adapters