A Few Head Scratchers

Love it or hate it, physics is a demanding subject. It defines much of our knowledge and experience in a daunting variety of ways. But really, you do love physics, don't you? On Uncertain Principles, Chad Orzel describes a modern implementation of "Maxwell's Demon," a dreamed-of 19th century device that could "cool a gas without obviously increasing entropy." While this may smack of perpetual motion, researchers have taken first steps toward realizing Maxwell's mechanism, using angled traps and lasers to winnow lower-energy atoms from a gas sample. On Starts With A Bang, Ethan Siegel explains the relative homogeneity of the solar system by imagining Jupiter much closer to the sun. At that distance its thick atmosphere would boil off, leaving behind "a hard, rocky core not all that different from our planet, except in terms of size and density." And on Built on Facts, Matt Springer expounds on the dynamics of a Foucault pendulum, which can "swing freely in any direction" and give the illusion that it rotates the plane of its swing. Matt also includes pictures of a new pendulum at the beautiful George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy at Texas A&M.

Links below the fold.

• Single-Photon Cooling: Making Maxwell's Demon on Uncertain Principles
• Q & A: Inside a Gas Giant on Starts With A Bang!
• Pondering a Ponderous Pendulum on Built On Facts