The lowdown on the highest energy light

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Incredible hulking facts about gamma rays

From lightning to the death of electrons, the highest-energy form of light is everywhere

For Symmetry Magazine:

Gamma rays are the most energetic type of light, packing a punch strong enough to pierce through metal or concrete barriers. More energetic than X-rays, they are born in the chaos of exploding stars, the annihilation of electrons and the decay of radioactive atoms. And today, medical scientists have a fine enough control of them to use them for surgery. Here are seven amazing facts about these powerful photons. [Read the rest at Symmetry Magazine]

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Nuclear pasta and neutron stars

[ This blog is dedicated to tracking my most recent publications. Subscribe to the feed to keep up with all the science stories I write! ]

The Inside of a Neutron Star Looks Spookily Familiar

Exotic ultra-compressed matter can look like pasta, among other things

Two phases of matter found in neutron stars are featured in this recent Dinosaur Comic; click to see the whole thing. (Slightly naughty language included.) [Credit: Ryan North]

Two phases of matter found in neutron stars are featured in this recent Dinosaur Comic; click to see the whole thing. (Slightly naughty language included.) [Credit: Ryan North]

For Nautilus:

Hot fluids of neutrons that flow without friction, superconductors made of protons, and a solid crust built of exotic atoms—features like these make neutron stars some of the strangest objects we’ve found in the cosmos so far. They pack all the mass of a star into a sphere the size of a city, resulting in states of matter we just don’t have on Earth.

And yet, despite their extreme weirdness, neutron stars contain a mishmash of vaguely familiar features, as if seen darkly through a funhouse mirror. One of the weirdest is the fact that deep inside a neutron star you can find a whole menu full of (nuclear) pasta. [Read the rest at Nautilus…]

GLaDOS, the manipulative computer system from the Portal games. The title of this post is a line from the Aeon article that was cut before publication, but I loved it so much I had to use it anyway. [Credit: Half-Life wiki]

It’s one of those nagging thoughts many of us have had: is our existence a reality or an illusion? Philosophers and scientists have grappled with the question, though today much of the discussion focuses on a related question: do we live in a computer simulation? In my (first hopefully of multiple) essays for Aeon magazine, I discussed one possible formulation of the question and how it could be answered — but also why the question may be less scientifically meaningful than many popular accounts would have you believe.

The idea isn’t as crazy as it sounds. A pair of philosophers recently argued that if we accept the eventual complexity of computer hardware, it’s quite probable we’re already part of an ‘ancestor simulation’, a virtual recreation of humanity’s past. Meanwhile, a trio of nuclear physicists has proposed a way to test this hypothesis, based on the notion that every scientific programme makes simplifying assumptions. If we live in a simulation, the thinking goes, we might be able to use experiments to detect these assumptions.

However, both of these perspectives, logical and empirical, leave open the possibility that we could be living in a simulation without being able to tell the difference. [read more….]

Sinners in the hands of an angry GLaDOS

(Since my weekly round-up experiment seems to have failed horribly, I’m going to try to go back to linking and summarizing individual articles I’ve written around the web on this blog. We’ll see if I keep it up!)

The great physicist Chien-Shiung Wu in 1958. [Credit: Smithsonian Institution]

The great physicist Chien-Shiung Wu in 1958. [Credit: Smithsonian Institution]

Chien-Shiung Wu is one of those physicists that everyone should know about, but not enough do. A veteran of the Manhattan Project, she went on to become the world’s expert on beta decay: the process by which an atomic nucleus changes into another element, emitting an electron (or positron) in the process. In the 1950s, she realized beta decay would be a way to test a fascinating new theory of the weak force, which predicted that there should be a fundamental asymmetry between processes occurring in different directions. Her experiment was the first observation of parity violation, which opened up a wealth of new results, leading ultimately to the discovery of the Higgs boson.

For Double X Science, I commemorated this discovery, explaining why it’s important and how weird it is. It would seem that the laws of physics shouldn’t depend on which direction a process occurs, yet that’s the way the Universe works!

Wu realized she could test this idea in the lab after discussions with her colleagues Tsung-Dao Lee and Chen-Ning Yang, who laid the theoretical groundwork for understanding the weak force. She recruited Henry Boorse, Mark Zemansky, and Ernest Ambler, who were skilled at experiments at very low temperatures. It’s a great illustration of the collaborative nature of science: Lee and Yang provided theoretical knowledge, but needed Wu to design and perform the experiment; Wu in her turn brought in experts in low-temperature physics to provide expertise in an area unfamiliar to her. (On a more sour note, Lee and Yang won the Nobel Prize for the discovery of parity violation, but Wu and her fellow lab workers were passed over.) [Read more…]

Madame Wu and the backward Universe

Danish physicist Niels Bohr, whose model of atoms helped explain the spectrum of light emitted and absorbed by different elements, as illustrated by the spectrum emitted by the Sun. [Credits: AB Lagrelius & Westphal, via Wikipedia (Niels Bohr photo); N.A.Sharp, NOAO/NSO/Kitt Peak FTS/AURA/NSF (solar spectrum); moi (composite)]

Danish physicist Niels Bohr, whose model of atoms helped explain the spectrum of light emitted and absorbed by different elements, as illustrated by the spectrum emitted by the Sun. [Credits: AB Lagrelius & Westphal, via Wikipedia (Niels Bohr photo); N.A.Sharp, NOAO/NSO/Kitt Peak FTS/AURA/NSF (solar spectrum); moi (composite)]

Many of us are familiar with the Bohr atom: a simple model with a nucleus and planet-like electrons orbiting in circular paths. It’s a useful picture, even though it’s not complete. Bohr proposed it in 1913, but it took about ten more years for physicists to work out why it worked — and to refine it into the quantum-mechanical picture of atoms we have today. However, we’re still probing the structure of atoms, especially the really bizarre behaviors under extreme conditions. Bohr’s contributions are still relevant today.

Despite a century of work, atomic physics is not a quiet field. Researchers continue to probe the structure of atoms, especially in their more extreme and exotic forms, to help understand the nature of electron interactions. They’ve created anti-atoms of antiprotons and positrons to see if they have the same spectra as their matter counterparts or even to see if they fall up instead of down in a gravitational field. Others have made huge atoms by exciting electrons nearly to the point where they break free, and some have made even more exotic “hollow atoms,” where the inner electrons of atoms are stripped out while the outer electrons are left in place. [Read more…]

A century of the Bohr atom