It’s based on the computer algebra package LiE, written by M. A. A. van Leeuwen, A. M. Cohen and B. Lisser in the early 90’s. They chose to implement a proprietary scripting language as a wrapper for all the fancy mathematical algorithms. While this language is useful for interactive computations and short scripts, python is more expressive and powerful — definitely what you want when exploring your favorite exceptional group.
A Fun Example
Here’s an example of using lie to do a calculation that’s near and dear to every high energy theorist’s heart. We’ll show how the 10 + 5bar + 1 representation of SU(5) contains a single standard model generation. First we’ll fire up python and import the lie module. Continue reading…
The snarXiv is a random high-energy theory paper generator incorporating all the latest trends, entropic reasoning, and exciting moduli spaces. The arXiv is similar, but occasionally less random.
Actually, the snarXiv only generates tantalizing titles and abstracts at the moment, while the arXiv delivers matching papers as well. Details of the implementation are below. I’m the author, and I don’t remember exactly why I decided to do this. I did already have the framework lying around from a previous project, and I swear I spent more time doing research last weekend than implementing snarXiv.org.
Suggested Uses for the snarXiv
If you’re a graduate student, gloomily read through the abstracts, thinking to yourself that you don’t understand papers on the real arXiv any better.
If you’re a post-doc, reload until you find something to work on.
If you’re a professor, get really excited when a paper claims to solve the hierarchy problem, the little hierarchy problem, the mu problem, and the confinement problem. Then experience profound disappointment.
If you’re a famous physicist, keep reloading until you see your name on something, then claim credit for it. Continue reading…
Basically it is a result of static electricity created by friction as materials of dissimilar material strike against each other. In this case titanium/nickel blades moving through the air and dust. It occurs on the ground as well, but you don’t usually see it as much unless the aircraft is landing or taking off. The most common time is when fuel is being pumped. When large tankers are being fueled they must be grounded to prevent static electricity from discharging and creating explosions.
The episode about theorists is unsurprisingly entitled Problems, and features a number of good moments, from signs at the LHC that read “Risk of Liquid Air,” to enormous chalkboards covered with Feynman diagrams, to the hilarious expressions of all-too-familiar grad student angst (“sometimes I almost want to give up everything”).
’Problems’ travels to Paris for a look at some of the theoretical work behind the ‘Eurostar’ paper. Gavin and his PhD student Mathieu explore the mathematics behind the behaviour of fundamental particles, and we have an update on the ‘incident’ which is holding up work at the LHC.
One of my favorite quotes is an observation that I didn’t fully understand until well into graduate school:
I think one of the hardest parts of research is not so much trying to solve a problem, as figuring out which problem you’re going to solve.
It’s absolutely true. The most exciting problems are simultaneously easy enough to be solvable, and hard enough to teach you something deep while you’re solving them. So far, for me, these have been hard to come by. My impression, based on the work that’s been done by my professors, is that a sense for the right problems is something you develop slowly over time, no matter how clever you are.
And as ridiculous and depressed as the poor Ph.D. student sounds in places, I completely understand what he’s feeling. The realization that theoretical physics is hard (and I mean real physics, not classwork), is something that comes in waves, and really only starts to hit in graduate school. It’s a little scary — you’ve got to grow up fast, or go do something else.
Usually, damage to the eyes from looking at the Sun happens during a total solar eclipse. The eclipse itself doesn’t hurt you — after all, the point of the eclipse is that the Sun is covered by the Moon! — but the damage happens in the moments right after the eclipse. While the Sun is blocked, your pupil dilates to let in more light, so when the first sliver of the brilliant Sun reappears your eye is flooded with light. This can cause damage to your retina called solar retinopathy. It’s actually not heat damage, but photochemical; the flood of UV light actually alters the chemistry of your cells, damaging them.
In general, the damage is minor and can heal well, though there can be some permanent though relatively minor effects (in other words, you still shouldn’t stare at the Sun). Usually the damage is worse in children because their lenses let in more blue light (the lens yellows with age, acting as a natural filter for UV light). […]
Incidentally, using sunglasses to look at the Sun can actually make things worse, since they block visible light and your pupil dilates to compensate. If you want to observe the Sun — and I recommend it, because it’s fascinating and utterly beautiful — then read Mr Eclipse’s guide to safe solar viewing. It’s a site for sore eyes.
The Sun is not an average star […] As with most things in nature, the number of objects depends on the size. There are very few high mass stars, more intermediate mass stars, and gazillions of low mass stars. Roughly 10% of all stars by number in the Milky Way Galaxy are like the Sun, which means that very few are more massive. Even being conservative, I’d say that the Sun is more massive than 80% of the stars in the Galaxy.
As I suspect most high energy physicists do, I stay acutely aware of what’s happening on Lubos Motl’s blog. Today, he offered a particularly illuminating analogy describing our relationship to some current physical theories
So we are somewhat similar to a primitive tribe that finds a washing machine (produced by someone else). At the beginning, they will use it as a fridge. As their knowledge increases, they will learn how to do the laundry. However, if they become even more skillful, they may update the device a bit — or press a hidden button — and use it as a fridge, too. I didn’t tell you: it was one of the washing machines that can also cool the clothes down.
