Friday, 30 March 2012

Measurements of Jet Substructure

One of the hot topics in the particle theory community at the moment is the use of jet substructure.  Jets are one of the most common types of objects we actually see in colliders: streams of roughly collinear particles.  They arise due to the fact that the strong nuclear force is, well, strong.  The fundamental particles that interact through this force---quarks and gluons---can not exist in isolation.  If you try and pull two quarks apart, for example, the energy in the interaction between them is so great it can spontaneously create more particles from the vacuum.  This means that when a particle collider like the LHC creates a quark or gluon in an interaction, that quark or gluon quickly acquires a number of followers which bind into (meta-)stable particles like pions, kaons, protons and neutrons.

These collections of particles are what show up in the actual detectors.  In older experiments, all we really cared about was the direction and energy of these things, which is roughly the same as the original quark or gluon.  You can do a lot of good physics just on that information alone.  But two things are different about the LHC.  First, the angular resolution of the experiments is much better, allowing us to truly resolve the individual particles within the jet.  Second, the large energy of the collisions leads to new types of events where heavy objects like Ws, Zs and tops can be produced with relativistic velocities.

Apollo 11 Engines to be Recovered

According to the Guardian, the Apollo 11 engines have been found on the Atlantic Ocean floor by a team lead by the Amazon Chief Executive, Jeff Bezos.  He has plans to attempt to recover them, with the goal of placing them on public display.

This is very exciting news.  The Apollo missions were an excellent example of what we can achieve as a species through science and engineering.  The Saturn V rockets are pretty awe-inspiring, too; I saw the one on display at the Kennedy space centre, and it's huge.  But to see the actual ones to propel the first humans to ever walk on another celestial body would be magnificent.  The only problem is that by the time they are put on display, I'll probably have left North America!  But I'm sure I can wangle a visit before or after a conference.

Wednesday, 28 March 2012


I was first introduced to roguelikes through Angband.  About three years ago, a friend lent me an old laptop on a long-term basis that eventually became a donation.  (It was a really old machine.)  I found Angband hidden on the hard drive, and started playing it; it wasn't long before I was hooked.

Monday, 26 March 2012

Really Big Microscopes

One natural question for the non-scientist is why we need to build particle accelerators and colliders.  I don't mean why in the sense of what we hope to learn, and why it's important [1]; I mean why these are the best tools for the job.  After all, when most people want to look at something small, they use a magnifying glass or microscope.  What's wrong with just building a more powerful lens to study the smallest scales of nature?

Sunday, 25 March 2012

Evil, or Just Stupid?

It's really tempting, as a non-American, to laugh at the problems the USA has with religion.  Of course, no small amount of that is nervous laughter at the prospect that the religious fanatics might get serious power, and then we're all in trouble, but most of it is the hope that we're superior in some way.

We aren't, of course, and news like this reminds us of that fact:
Anti-abortion campaigners in Britain are making controversial claims that abortions are linked to an increased risk of breast cancer, in a presentation to children in school which has been obtained by the Guardian.
 That link to breast cancer?
A study co-ordinated by Cancer Research UK and published in the Lancet has shown that abortion does not increase the risk of breast cancer.
But why let facts get in the way religious dogma?

This group also opposes abortion in the case of rape, saying that it can be a "second trauma".  Well, I'm sure that would be true for some people, but certainly not for all; surely, the only person who can make that choice is the woman involved.

This group also opposes sex education, of course, because why endorse something that stops unwanted pregnancies?  It's almost as if the entire thing is about controlling people's sex lives, forcing those dirty sluts who have sex to be punished, and generally reducing women to the role of breeders!

Now if you'll excuse me, I need to go look at pictures of cute animals till I no longer need to vomit.

Wednesday, 21 March 2012

It's Impossible to Disagree

I've just found out about Aumann's Agreement Theorem, a mathematical proof that (rational) people cannot agree to disagree.  That's got to be up there with the Banach-Tarski paradox for mathematical results that make me laugh.

Another Tuesday, Another Primary

So Romney has won Illinois by more than ten points over Santorum.

Santorum's failure to win Ohio back on Super Tuesday probably marked the end of his chances of winning the nomination through delegates.  This defeat likely ends his other option, stopping Romney getting a majority and successfully appealing to unbound delegates.  The thing I can't help but wonder, though, is if Santorum himself knows this?  He certainly didn't seem to treat Illinois with the importance it deserved, travelling to Puerto Rico (and promptly putting his foot in his mouth).  Nate Silver suggested that Santorum might have decided to be an honourable second place, angling for Romney's running mate.  Then Santorum accused Romney of lacking a core.

Still, if Santorum really thinks he can still turn things around, I'm not going to complain.  I'll just make some more popcorn.

Tuesday, 20 March 2012

Politicians Are (Insert Epithet of Choice)

Since I've already followed up on one of my posts from yesterday, lets do the same for the other and talk about some conservative politicians, this time back home in the UK.  The current Conservative/Lib Dem coalition has been pushing for heavy cuts to public services on the grounds that the treasury was in a mess and savings had to be made.  I wasn't exactly a fan of that idea, but there's no denying that Labour really cocked things up when they were in power.  But when you get stuff like this, cutting the top rate of income tax, it's hard to believe that this isn't a deliberate attempt to fuck the poor.

The coalition is currently claiming that actually, the rich will be worse off as a result of other changes to be introduced at the same time.  Well, I've tried to construct a coherent response but I can't, so let me just say bollocks.

Now I think I'll go have a drink.


Yesterday, I blogged about something older than me that I spend a lot of time thinking about, the Standard Model of particle physics.  Today I'm going to do the same thing, this time talking about roguelikes.

Roguelikes are a class of computer game imaginatively titled because they are like Rogue.  Rogue, released in 1980, was a dungeon crawler with an excuse plot---enter dungeon, find magic item (the Amulet of Yendor) and return without dying.  The game was very popular for its time, likely in part due to its user interface: while most similar games of the time where text-based, Rogue had primitive graphics:

You, the player, are represented by the @.  (Image source: wikipedia, released under the Creative Commons 3.0 license.)

Monday, 19 March 2012

Puerto Rico Republican Primary

Today was the republican presidential primary in Puerto Rico.  Despite not being an American, I've been following this election quite closely.  Some of it is schadenfreude; it's fun to point and laugh at the candidates.  Some of it is bile fascination; I have American friends, and I dread the thought of them being governed by any of these clowns.  The rest of it is a general fascination with elections that I can't quite explain.

At this point, of course, the primary has become quite dull.  Romney will almost certainly win, a fact that has been clear since Santorum failed to win Ohio on Super Tuesday.  This is a good thing; not that I like Romney, but he's less dangerous and crazy than his competitors.  Some people suggest that Obama supporters should hope for a Santorum victory, on the grounds that he'd be easier in the general election; my office mate is one of them.  But quite frankly I don't think there is anyone too crazy and right-wing for the Americans to elect them, so I want Romney to win the primary.

Puerto Rico isn't that important in the primary, thanks to not being a state and all.  However, it was amusing to watch Santorum do his best to self-destruct on the back of his wins in Alabama and Mississippi earlier this month.  It's no surprise to see Romney not only win, but by a crushing margin.

Attention now turns to Illinois, which represents Santorum's last realistic chance to change the narrative of the primary.  He won't, and I'll laugh.

In Which I Ramble About The Higgs

It's an exciting time to be a particle physicist.

One of the main reasons, and the focus of this post, is related to the one remaining undiscovered particle of the Standard Model---the Higgs.  The Standard Model of particle physics essentially came together during the seventies, making it older than me, and it has passed almost all experimental tests since then.[1]  In particular, it predicted the existence of several particles that have since been discovered, including the W and Z bosons and the top quark.  But the key to the model, what in many ways defines it, is the Higgs; and this particle will either be found or ruled out by the end of the year.  Indeed, the ATLAS and CMS experiments at the Large Hadron Collider both reported possible hints of the Higgs last December.

An Introduction

The fun thing about a first post is that no one will read when it goes up.  So this is more a reference for the future, if anyone gets curious beyond the sound bites to the right.

I am a physicist postdoc, which means that I have a PhD but universities and research institutes are not yet willing to offer me permanent positions.  Instead, my current and next jobs are explicitly temporary, where I will hopefully prove that I can do useful, interesting independent work so that I can get a more senior position next time around.  I work on particle physics phenomenology, which in lay terms means I am most interested in the results of the Large Hadron Collider at CERN; but I'm a theorist, not a member of any of the experimental collaborations.  I have other interests too, such as Dark Matter, but the LHC is my main focus.