The Longest Now

See John Baez’s Open Questions in Physics.

Entanglement, Decoherence, and the Quantum/Classical Boundary

via Johannes Koelman.

Today CERN and FERMILAB announced 5σ confirmation of the existence of the Higgs boson [1], inspiring a burst of heady live coverage from the Guardian. (CERN had leaked a video about the discovery the day before, so everyone knew what was coming, and turned up for today’s Higgs seminar. All of the scientists who had worked on early versions of the theory that pointed towards such a boson also flew in the the seminar, which continues tomorrow.)

CERN has posted and archived beautiful 360-degree photos of the day, a video of the press conference (rather dull), and will soon post a recording of the day’s seminar (which was live-streamed and amazing; come back for it tomorrow).

The media as usual tries valiantly to explain things in a down-to-earth way that is both simplistic and true, but is generally failing. As with a few other recent scientific breakthroughs, I am grateful that Wikipedia offers solid explanations of the topics at hand, and through the magic of hyperlinks (which news agencies are still struggling with 🙂 allows exploration of the topics in as much depth as you like.

Related reading: supersymmetry, scalar field theory, htlhcdtwy.

[1] Note the careful, conservative trend in particle physics: the labs making the discovery are all quick to say they’ve discovered the existence of at least one new particle, which matches the profile of the Higgs boson; it could be one or more of its sibling bosons that have been discovered – supersymmetry suggests there could be 5 of them.

Graphene is one of the most remarkable substances in the world. Physicists Andre Geim and Konstantin Novoselov won the Nobel Prize for their work to manufacture single-layer sheets of it only six years after their first success.

Now it is entering mass production, and being considered for the sort of applications that currently rely on nanotubes. It might also be suitable for very different macro-scale tasks, as sheets of graphene can theoretically be arbitrarily broad (while just one atom thick), once a suitable production process is worked out.

In practice, it is still hard to produce monolayer sheets of graphene, but we are making thinner and thinner ‘platelets’ by exfoliating them from larger chunks. Many current applications depend on the bulk surface area available for interaction with the environment, and platelets are often marketed in terms of their surface area per unit weight (in m^2/g).

The properties of commercially produced graphene are 1-2 magnitudes less than the extreme values measurable with pure monolayer sheets. So on top of the practical economic applications today, there is a decade of Moore-like improvement to look forward to. Costs of production vary according to purity: low-grade graphene (platelets 3-10 layers thick and a few dozen microns wide) are available for under $300/kg, while higher-quality graphene (1-3 layers thick, hundreds of microns wide) can range from $10/gram to $100/gram, and only in small quantities.

Finally, my favorite factoid about graphene (out of MANY): you can use a sheet of it to directly measure the fine structure constant: each layer absorbs πα (that’s pi times the fine structure constant) of light that passes through it!