The week in review (August 18-24)

Granulation on the surface of the Sun, created by rising bubbles of hot plasma. Fluctuations in these bubbles can be measured on distant stars, which provides a way to calculate the stars' surface gravity. [Credit: Hinode JAXA/NASA/PPARC]

Granulation on the surface of the Sun, created by rising bubbles of hot plasma. Fluctuations in these bubbles can be measured on distant stars, which provides a way to calculate the stars’ surface gravity. [Credit: Hinode JAXA/NASA/PPARC]

I’ve been remiss in blogging at Bowler Hat Science, largely because…well, I’ve been writing too much elsewhere. So, I’m going to try something different: instead of blogging each new article I write in a separate entry, I’ll write a single post summarizing everything in one go.

  • How I learned to stop worrying and love tolerate the multiverse (Galileo’s Pendulum): My explanation of cosmology involving parallel universes is a response to a piece placing the multiverse in the same category as telepathy. While I’m not a fan of the multiverse concept, I reluctantly accept that it could be a correct description of reality.
  • An Arguably Unreal Particle Powers All of Your Electronics (Nautilus): Electrons in solids behave differently than their wild cousins. In some materials, the electronic and magnetic properties act as though they arise from particles that are lighter or heavier than electrons, or multiple types of particles with strange spins or electric charges. Are these quasiparticles real?
  • Kepler finds stars’ flickers reveal the gravity at their surface (Ars Technica): The Kepler observatory’s primary mission was to hunt for exoplanets, but arguably it’s been equally valuable for studying stars. A new study revealed a way to measure a star’s surface gravity by timing short-duration fluctuations — the rippling of hot plasma bubbles on the surface known as granulation (see above image).
  • Destruction and beauty in a distant galaxy (Galileo’s Pendulum): The giant galaxy M87 has a correspondingly huge black hole at its heart. That black hole in turn generates an enormous jet of matter extending 5,000 light-years, which fluctuates in a way we can see with telescopes. In that way, an engine of destruction shapes its environment and produces a thing of beauty.
  • The Freaky Celestial Events We See—and the Ones We Don’t (Nautilus): In another faraway galaxy, a black hole destroyed a star, producing a burst of gamma rays that lingered for months. This event is the only one of its kind we’ve yet seen, prompting the question: how do we evaluate events that are unique? How can we estimate how likely they truly are, especially if we’re seeing them from a privileged angle?
  • This isn’t writing, but after listing two black hole articles in a row, it seems a good time to advertise my Introduction to Black Holes online class in October! Sign up to learn all* about black holes. *All = what I can cover in four hours of class time.
  • Warp Speed? Not So Fast (Slate): Many articles have appeared over the last year or so profiling a NASA researcher, whose research supposedly could lead to a faster-than-light propulsion system. The problem: very little actual information about his work is known, and what he’s said publicly contradicts what we understand about general relativity and quantum physics.

Speaking of warp drives, I’ll conclude with this wonderful video of Patrick Stewart engaging with some obvious Star Trek fans.

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Typically, reversing the direction of time twice is the same as never reversing it at all. Think of running an old-fashioned filmstrip backward, then forward (not an unusual experience for those of us um…of a certain generation): the film will look the same as though you never ran it backward. However, a particular uranium compound, URu2Si2, may break that rule. In that sense, it behaves akin to a spinor, the mathematical description of particles like electrons, protons, and so forth. (For more on spinors,  read my earlier post at Galileo’s Pendulum.) This model could explain all the weird properties of the uranium compound, including its strange magnetic behaviors.

A new model may help resolve the confusion by proposing a different form of symmetry breaking. Ordinarily, if you reverse the direction of time (akin to running a movie backward), then reverse it again, everything comes back to normal. For the particular uranium-rubidium-silicon compound at issue, Premala Chandra, Piers Coleman, and Rebecca Flint argued that symmetry is broken: it will not behave normally even under double time reversal. While a literal double reversing of time isn’t possible in the lab, the broken symmetry has a measurable consequence in the distortion of electron orbits in the uranium. If confirmed, this hypothesis could resolve a thirty-year-old mystery. [Read more…]

When the reverse of reverse isn’t forward: weird symmetry in uranium compound

Metal tends to be opaque. However, if you perforate it with small holes in a certain pattern, it will still transmit some light—even if the holes are smaller than the wavelength of the light! This is known as extraordinary optical transmission (EOT), which has found uses in a number of devices since its discovery in the 1990s. However, a full understanding of the phenomenon has proven elusive. (That’s such a journalist way to put it, ain’t it?) A new experiment may have shown that the transmission is driven by two separate wave effects, and sorted out the role each plays in EOT.

Ordinarily, light can pass through an opaque barrier only if the barrier is pierced with openings larger than the light’s wavelength. (This also applies to all manner of waves, including sound and water waves.) That’s why EOT is fascinating: the holes are smaller than the wavelength, yet a substantial amount of light still gets through something that would ordinarily be opaque. Oddly, making the material thinner—and therefore more transparent—decreases the EOT effect. [Read more….]

Holey metal, Batman!