Number the Stars

My uncle asked me an interesting physics-related question the other day, so I thought I’d share the question and my answer on the blog:

Q: If a trillion seconds take 30,000 years and there are three trillion stars in the universe, it would take ninety thousand years to count them at one per second. So how do we know?
Before you click through to my explanation, why not take a few minutes to think about how you might answer this?  How DO we count that which is essentially uncountable?

A hint, by way of another question: How would you count the number of grains of sand on a beach?  What’s your strategy for those “guess how many candies are in this jar” type of games?

Now, after you’ve mulled it over for a little bit, here’s my response:

Bloggers Pseudonymous

As a semi-pseudonymous blogger, I appreciated the post on the difference between anonymity and pseudonymity at Uncertain Principles, in response to the vindictive outing of Publius, a formerly pseudonymous blogger:

Someone like Publius, or FSP [Female Science Professor], or Mark Twain writes under a different name than their given name. This does not mean that they are without identity, though– quite the contrary. They write consistently under a single name, and this body of work establishes an identity for them that is every bit as solid as the identity that “Chad Orzel” establishes for me.

I haven’t tried to figure out who FSP is, because it doesn’t matter. The alias is enough to establish an identity, as revealed through years worth of blog posts. And that’s really the thing that matters in blogdom, or even in literature.

Pseudonymity has a long and honorable tradition in literature, and Publius and Female Science Professor fit in that. Anonymity, not so much. It’s a distinction that matters.

There are plenty of good reasons to use a pseudonym, some of which I’ve talked about before, and which you can find in other discussions about the perils of blogging.  But I have a different reason at this point in my blogging career that has become more clear to me recently:

I don’t like to have a reputation that precedes me.

New Blog in the Blogrolls

I’d like to draw attention to a new blog in my links section.  The authors are three fellow grad students studying high energy physics, covering the range of experiment, phenomenology, and theory.  Combining their diverse intellects, they have come up with the name High Energy PhDs.

From their introductory post back in November ‘08, here is a description of what you will find on their blog:

Short reviews of topics in high energy physics. Our main goal is to generate an online discussion where we can jot down summaries of interesting ideas.

Accessible summaries. We are also interested in writing posts that will bridge the divides between hep-th/hep-ph/hep-ex communities. While these may not be “public outreach” level, they should be accessible to other graduate students in physics.

News. Some discussion of recent events in high energy physics, e.g. LHC commissioning.

Grad student resources. We will also have posts dedicated to grad student resources for items such as post-doc hunting, publishing, finding review articles, adviser management, etc.

I look forward to making use of their list of Resources for Learning New Topics.  Their discussion of Renormalization looks good too, which will hopefully help me make sense of that tricky topic as I try to teach myself some field theory.  You can also find some reviews of technical papers, and discussions of experiments like MiniBooNE.

You’re Like School in the Summer…

No class!

Or at least that’s how the corny old Fat Albert joke goes.  Of course, there’s always summer school… In high school, these were remedial classes that you wanted to avoid.  In college, maybe you’re trying to improve a grade, or maybe stay on track to graduate in four years.  But in grad school, summer schools are something entirely different.

Summertime is a time to focus on your research, without the distractions of tests, homeworks, and (hopefully) teaching duties.  But many grad students, at least in physics, take the summer as an opportunity to attend summer schools, which are short, intense sessions aimed at advanced grad students that are held at various institutions around the country and the world.  These schools bring in lecturers to present short courses on different topics within a certain subfield, often focused on a particular theme for that year.  The purpose is primarily to broaden the students’ exposure to the field, getting them out of the narrow focus that dissertation research requires.

Not everyone has the resources or the ability to attend one of these schools, but, thanks to modern technology, you can still participate by watching the lectures online.  In particular, the Theoretical Advanced Study Institute in Elementary Particle Physics (TASI) is going on now, in Boulder, CO.  You can find the links to lecture videos and notes here.  So far, it looks like they are getting the videos posted the day after the lectures occur, so you can make time to take a course or two that looks interesting (the upcoming lineup of talks is also found on the same site).  I have started the course on Supersymmetry and the MSSM, but I am particularly looking forward to the lectures on the AdS/CFT duality, as that pertains to my summer research project.

Academic Forms of Address

Chad at Uncertain Principles has a post addressing the topic of forms of address in academia.  Specifically, he asks how academics refer to their students in recommendation letters.

I thought I’d flip the script on this one, and talk about how students address their professors.  In my undergrad experience, I almost always referred to my professors as “Dr. LastName.”  This applied even to my advisors, whom I worked with pretty closely over the course of a few years.  I was never quite sure if and when I could make the transition to address these professors by their first names.  Although they signed their emails by their first names and had other students address them on this basis, I was always wary of assuming this level of familiarity.

Now at Minnesota, I’ve noticed that everyone refers to and addresses the professors as Professor LastName, or even simply “Professor.”  I’m not sure if this is a standard protocol (after all, Professor is a more exclusive club than Doctor), or if it’s just one of those things that varies from place to place.

What is a Particle?

For my money, particle physics is just about the coolest thing in the world.  The scientifically curious public evidently thinks it’s pretty cool too, as evidenced by the books and articles aimed at the general public that far outnumber the coverage given to other areas of physics, much to the chagrin of the people who study those fields.

So you’ve probably heard about many concepts about particle physics.  I’m sure you know about atoms, electrons and the nucleus.  Maybe quarks, neutrinos, and the higgs boson sound vaguely familiar.  And the media hype around the LHC startup has been hard to ignore.

In this series of posts, I hope to give you a better understanding of what particle physics is about.  I hope these posts will be of interest to both the novice and the relative expert — anyone who wants to explore the question of just what it is we mean when we talk about a fundamental particle.

ATOMS

Before we talk about particle physics, we have to have a little context.  Let’s start with the universe.

Okay, now let’s zoom in juuust a little bit, down to the level of atoms.  This is where I will begin our discussion of what it means to be a particle.  Atoms were originally posited to be the smallest, “uncuttable” building blocks of all matter, the first candidate for a fundamental particle.  This idea, originally put forth by philosophers such as Democritus, was in opposition to the idea that matter was a continuum that could be divided into smaller pieces ad infinitum.  As chemistry developed and new elements were discovered and isolated, the atomic hypothesis moved from the realm of philosophy and became an essential scientific concept.

However, we’re not all that interested in the development of chemistry.  I want to focus instead on what sort of a mental picture this model gives us.  In other words, just what sort of properties does a “fundamental particle” have in this atomic theory?

Questions for Kaku?

Michio Kaku, physicist, author, and nearly omnipresent TV science dude, is speaking at the U of M bookstore today.  I am thinking about going to hear him talk (presumably about his new book, The Physics of the Impossible).  I am not sure that there is a Q&A session accompanying the talk, but if you have any good questions that I should ask, let me know in the comments.

Kaku’s book Hyperspace was one of the first physics books that I read as a kid, after Stephen Hawking’s A Brief History of Time.  I don’t remember a whole lot about what he wrote about, but I know that it piqued my interest in physics, and got me wondering about higher dimensions, so in that sense it was an important book in my life.  I haven’t read it in years, and I never read any of his other books.

Missing the Important Stuff

Bear with me as I force an analogy between watching basketball and grading physics quizzes.

When I watch basketball on TV, especially during March Madness, I’m often annoyed by the way they handle the replays.  After an exciting play, I’ll yell at the TV, begging for a replay so that I can see again exactly how the play developed.  When they do show the replay, I’ll often end up yelling at the TV again, because they left out all the important part of the play.

They show the shot being released, traveling through the air and splashing through the net, ignoring the pick and roll and the deft pass that set up the shot.  The time that the ball is in the air is really the least interesting part of that play.  The ball flies the same way every time, and we already know the result of the play.  Show us how they got there.

Or they show the dunk at the end of a fast break, hiding the defense that set up the break and the smart decicion making of the point guard that got the ball to the right player to finish the play.  The dunk gets the fans excited and shows up on Sports Center, but it doesn’t happen without the key plays that set it up.

Now the switch to physics…

Environment vs. Human Achievement?

As you may have heard, many individuals and municipalities will be observing Earth Hour tonight at 8:30 pm, your local time.  The idea is to raise awareness about the importance of energy conservation in combating global climate change.

The success that is reported in actual energy savings varies greatly, and it’s unclear how much of an impact this might have on the environment overall.  Several cities reported reductions in consumption between 1-10% during Earth Hour 2008, although some cities increased consumption, possibly because of the weather increasing the need for heating.  This is a savings of in the neighborhood of 100 metric tons of carbon dioxide emissions.

So, is a small decrease in consumption for one hour out out of the year really something to make a big fuss out of?  Not if that energy saving is all that comes out of it.  If you sit with the lights off for an hour, then go out and drag race your Hummer to the lake and dump toxic sludge in it, of course you’re not doing much good.  But if Earth Hour increases awareness of environmental concerns, and shows that participating governments are truly serious about enacting green policies, then a lot of good can come out of the Earth Hour project.

Of course, there’s been some criticism of Earth Hour, and a competing event scheduled for the same time called Human Achievement Hour.  The idea is to celebrate human achievements, one of the greatest of which is the ability to generate, control, and harness energy, all of which has been necessary for our modern human achievements.  I guess we’re supposed to celebrate this by doing what we normally do and leave the lights on.  Or maybe we should turn on lots of unnecessary lights?  Really, this “celebration” doesn’t seem like a true counter to Earth Hour, but simply a mockery.

But the real point here is that human achievement and environmentalism are in no way in opposition to one another.  If we enjoy all our modern conveniences without concern, and end up making our planet unlivable, that’s not really a human achievement, is it?

But if we can figure out how to keep those conveniences, all while preserving our environment?  Talk about a human achievement to be proud of.

St. Patrick’s Day

Lá Fhéile Pádraig Sona Daoibh!

That’s Irish for “Happy St. Patrick’s Day!”

In celebration, let’s take a look at a list of famous Irish physicists:

• Robert Boyle, discoverer of Boyle’s Law, the relationship between pressure and volume in an ideal gas.
• William Thomson, Lord Kelvin, one of the founding fathers of thermodynamics, and the namesake of the Kelvin temperature scale.
• William Hamilton, best known for reforming classical mechanics in the formalism know known as the Hamiltonian.  This approach is now essential in classical mechanics as well as quantum mechanics.
• George Stokes, who made important contributions to the study of fluid dynamics and mathematical physics, including the Navier-Stokes Equations and Stokes’ Theorem.
• Joseph Larmor, discoverer of Larmor precession, and the Lorentz Transformations, ostensibly before Lorentz himself discovered them, although only in the context of orbiting electrons.
• Erwin Schrödinger, one of the founders of quantum mechanics, and developer of Schrodinger’s Equation.  Yes, I know the name doesn’t seem Irish, and he was indeed born in Austria.  However, he founded the Dublin Institute for Advanced Studies on the request of the Irish Prime Minister, and became a naturalized Irish citizen during his 17 years in Dublin.