I've tried to describe here some of the current research areas that I think are particularly exciting, some I've written about and some I haven't. It's impossible, of course, to keep up with even a small fraction of the good ongoing science. This is my own biased view.

Quantum Non-locality

Since the famous paper of Einstein, Podolsky and Rosen in 1935, physicists have puzzled over the apparently nonlocal character of quantum physics. A famous argument due to John Bell in the mid 1960's demonstrated that if quantum theory is correct in its predictions, any "realistic" theory -- one that attributes real existing properties to reality, separate from their observation by humans -- must necessarily involve non-local interactions; that is, influences that travel faster than the speed of light. A series of experiments since then has demonstrated that quantum theory indeed seems to be correct, and the universe is nonlocal, although in a somewhat subtle way. I've written about this topic in a number of articles. See X or Y, for example.

However, all the experiments to date have, in fact, involved various "loopholes" due the inefficiency of particle detectors and so on. Year by year researchers come closer to closing these loopholes, while never seeming to get quite there. Consequently, physicists such as X or Y have argued that closing such loopholes may in fact be impossible. It could be, for example, that the states of the world that involve nonlocal interactions may be impossible to produce. Y even suggests that quantum theory may be derivable from some underlying theory with a classical flavour.

Quantum Measurement

Despite its immense success, quantum theory still suffers from a fundamental inconsistency. The theory implies -- and countless experiments verify -- that objects in the microworld (such as electrons) do very surprising things. In particular, they routinely exist in so-called "superimposed" states in which they can be in two or more places at once, or possess other contradictory properties. When we observe an electron it is definitely either here or there, but between observations they can do multiple things. A fundamental unresolved mystery is why we see these superpositions only in the microworld, yet never in large, macroscopic objects. This is known as the famous 'measurement" problem in quantum theory, and is the subject of intense ongoing effort. One of the mostb exciting ideas, pursued by Ian Percival, Phillip Pearle, Roger Penrose and others is that superpositions in large objects naturally decay very quickly into definite states, and hence cannot be observed. I wrote on this here. Another fascinating angle, suggested by X Adler, is that ??? An interesting review ia available here.

Complex Networks

Experimental Economics

The Evolution of Cooperation

Predicting Dynamic Systems

How to See the Future is a fairly recent article I wrote for New Scientist Magazine, which explores the scientific goal of foretelling the future of so-called "complex systems"; that is, of things like economic markets, ecosystems, the global climate and so on where you have many parts interacting in complicated ways and the link vetween cause and effect is hard to follow. Science is still pretty much in the dark here, but some very recent mathematical work suggests that our chances may actually be far better than we thought a few years ago. Here and here you'll find a couple of other articles, written for New Scientist and the business magazine strategy+business in which I describe various applications of these new ideas in predicting finanicial markets or practical business management. Here are links to my other articles, both recent and past, including the monthly column I write for Nature Physics.

Social Physics