Units and order of magnitude estimates.

One of the most important skills a physicist can have is to estimate the size of various effects without doing a detailed calculation. This basic skill is one of the hardest ones to learn, mostly because it is very easy to disbelieve: after all, you didn’t do a real calculation. But at the same time, [...]

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Opinions on the role of science and the stimulus package.

Dennis Overbye, in the New York Times, has some thoughts about science . You should also read the letter by David Gross and Eric Kandel on the Financial Times about why the stimulus package should also include science research. You should also be aware of the findings of the National Academy of Science ( I linked to [...]

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Scientific Blog Limericks

As I was walking near the sea shores Thinking about all my chores I met some girls who where pretty to see And as I talked about the Dirac sea It turned out they where whores.   Your homework for the week is to come up with an original Limerick using the title of your favorite science [...]

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Climbing down

Following David’s advice I’ll climb down from my theoretical ledge and rant a little bit, since I have no time to do anything more substantive. Every semester reaches some point where your time fractionalizes to smaller and smaller bits, where the number of small but urgent tasks exponentiates, and the ability to hold a single [...]

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This has not been my week….

In this blog we occasionally show our humanity and climb down from our theoretical speculations to talk about some aspects of our lives. Here is a sample. Yesterday I was late for one appointment (I plain forgot) and arrived very late in the end after bumping into someone who reminded me “where I should have [...]

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Everyday physics: the stress tensor.

You might think I have gone bonkers. When have you ever heard of the stress tensor being everyday physics? Don’t let nomenclature fool you. The stress tensor is as a matter of fact something that we have a lot of familiarity with, just not by that name. Consider for example a steel cable made of [...]

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Everyday physics: boats and ice float.

As you might have noticed, some objects float and some others don’t. Here below I have a rendition of a boat and a cube of ice floating.       Today, I will go on a bit about flotation. As a matter of fact, some of you might remember a puzzle with an egg I [...]

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Maldacena’s information paradox

Back in 2001, in a truly beautiful paper, Juan Maldacena formulated a version of Hawking’s information paradox, which has the added advantage that it could be discussed and analyzed in the context of a complete background independent theory of quantum gravity, namely that of the AdS/CFT correspondence. This variant is similar to the original paradox, [...]

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Comments on student evaluations

Over at Uncertain Principles, Chad asks for suggestions for minor tweaks in the student evaluation system. I thought I’ll add my two cents here, and ask the readers for their opinions. Just to be clear, like many others I think the current system serves no purpose whatsoever, and is often counter-productive. In my mind, any [...]

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Fading into obsolescence

So, as a matter of fact, I occasionally buy some computer games. Also I also occasionally buy new computers. Eventually it becomes hard to use an old computer if the computer is not able to operate the newest software available.  If I get bored, I might even try to install old games in a new [...]

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