Ross McKenzie points out an interesting exchange between Philip W Anderson and others (including Rudolf Peierls) in Letters to Physics Today on spontaneous symmetry breaking, here and here. The original article was on a history of electroweak unification.
As I understand it, Anderson distinguishes between two different types of symmetry breaking, one in which the ground state is not an eigenstate of the symmetry group, and one in which it is, with antiferromagnetism and superconductivity examples of the former and ferromagnetism an example of the latter. This is also reflected in the excitation spectrum of the system: spin waves in a ferromagnet have definite spin, but those in an antiferromagnet don't. Anderson also points out that spontaneous symmetry breaking in the context of particle physics is of the first type (cf. Higgs mechanism).
Here is an interesting read on Sokal's hoax. The following excerpt of John Wheeler's writing [1] is especially interesting:
The universe says to a physicist, "I supply the space and time for your existence. There was no before, before I came into being, and there will be no after [after] I cease to exist. You are an unimportant bit of matter located in an unimportant galaxy." "How shall we reply?" asks Wheeler. Shall we say, "Yes, OK universe, without you I would not have been able to come into being. Yet you, great system, are made of phenomena; and every phenomenon rests on an act of observation. You could not even exist without an elementary act of registration such as mine."
[1] Quantum Theory and Measurement, J. Wheeler, W. H. Zurek, eds., Princeton U. P., Princeton, N. J. (1983).
Here's an interesting general-audience perspective on Topological Insulators. This is not a piece fresh off the stove, though it's not old either. My favourite is the conclusion offered by Joel Moore
"There's something about many-particle quantum mechanics that causes perfection to emerge out of imperfection," he says. "That's somewhat cheering as far as our everyday lives are concerned."
I have come to think more and more of the importance of good mentors and the personal training and career advice they provide. A number of online resources exist on the subject, including:
— Nature Awards for Mentoring in Science and references there;
— Other Naturejobs articles: Mentors & Protégés (see also, The hands that guide); Mentoring mismatch
— Compact Between Postdoctoral Appointees and Their Mentors (see also, A better deal for postdocs and their mentors?);
— NPA's Mentoring Plans for Postdoctoral Scholars;
— MentorNet, an e-mentoring network.
A bit to my surprise, I have been selected as a journal keeper for the Naturejobs Postdoc Journal in 2010, based on an essay I submitted back in December 2009. That essay is now published as my first journal entry: Planning my next career?
A few nice articles on a career in science. I'll add some words of my own later.
- On Becoming a Scientist by Bruce Alberts
- A wake-up call by Bruce Alberts
- Audacious Science Series by Science Career Staff
Science News: Physicists Successfully Store and Retrieve Nothing
It sounds like a headline from the spoof newspaper The Onion, but for physicists, this is actually an achievement: Two teams have stored nothing in a puff of gas and then retrieved it a split second later.
I am attending a workshop at KITP on Sr2RuO4 starting this Monday, Dec 10th. I will be posting some news and development for my personal reference. It also has a wiki page.
Nature has a collection of articles on the "many-worlds" quntum theory 50 years after it was first expounded by Hugh Everett III for his PhD thesis. The articles have a running theme of science fiction as well. I have yet to read all of them, but the News Feature (subscription) and the Commentary articles are both nicely written.
It is said sometimes that physicists constantly simplify the problems they are trying to solve by considering simple models. This is true but not the whole story, or even the important part of it. Simple models must also be relevant, otherwise they are worthless. This is usually expressed by saying that the said simple model contains the important/relevant physics one is trying to address. This, I think, is far more crucial to what physicists do than the simplicity of their models which is a reflection of our modest abilities. It is a reflection of our immodest abilities in finding the correct solution.
The reason I am writing this is that today I saw Richard Muller's lecture webcast of Tue 11/7/2006, which started, due to the occasion, by his icecream model of elections. It is a simple model that argues there is no or little difference between the candidates in a two-party system. However, it does so by assuming a whole load of assumptions that are not explored in Muller's short discussion. For instance, it assumes there is a continuous, static, and spacially coordinated one-dimensional spectrum of political opinions. It also assumes that the candidates can move more or less continuously over this political spectrum without losing any votes on the opposite side of their oppponent. In short, it is a simple model, but one that does not contain the right physics.
