I Love Q, and now you can too!

I wrote a feature story for Physics World on an interesting little discovery about neutron stars, but unfortunately the article wasn’t in their free online edition. HOWEVER, the editors have kindly let me repost the article here in PDF format for free download! (Here’s the summary I wrote a few weeks ago.)

Physics World is a glossy magazine published by the Institute of Physics (IoP) in Europe. My articles are in the print version, but you can access them online by joining IoP (US$25 per year) and see everything they publish either through the Physics World website (which also has tons of free content) or the app, available on iTunes or Google Play.

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How can we see black holes if they’re invisible?

[ 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 Shadow of a Black Hole

From NOVA:

The invisible manifests itself through the visible: so say many of the great works of philosophy, poetry, and religion. It’s also true in physics: we can’t see atoms or electrons directly and dark matter seems to be entirely transparent, yet this invisible stuff makes and shapes the universe as we know it.

Then there are black holes: though they are the most extreme gravitational powerhouses in the cosmos, they are invisible to our telescopes. Black holes are the unseen hand steering the evolution of galaxies, sometimes encouraging new star formation, sometimes throttling it. The material they send jetting away changes the chemistry of entire galaxies. When they take the form of quasars and blazars, black holes are some of the brightest single objects in the universe, visible billions of light-years away. The biggest supermassive black holes are billions of times as massive as the Sun. They are engines of creation and destruction that put the known laws of physics to their most extreme test. Yet, we can’t actually see them. [read the rest at NOVA…]

This piece, which emphasizes the great science coming from the Event Horizon Telescope (EHT), is a  companion to my earlier NOVA essay, “Do we need to rewrite general relativity?”

The three little words every pulsar wants to hear

[ This blog is dedicated to tracking my most recent publications. Subscribe to the feed to keep up with all the science stories I write! UPDATE: you can now download this article in PDF format! See the follow-up post or the update below.]

I can’t help falling in Love with Q

The first page of my latest print article in Physics World. Unfortunately, there doesn't seem to be an online version.

The first page of my latest print article in Physics World. Unfortunately, there doesn’t seem to be an online version.

From Physics World:

The dancers are an elegant pair. Clothed in the fabric of space–time, they are driven by the music of gravity and make a stately orbit around one another once every two-and-a-half hours. They pirouette as they move – one spins once every few seconds while the other spins many times per second – and each one of their twirls is marked by an intense flash of light. The dancing partners are pulsars – spinning neutron stars that send a regular blip of light our way.

Named PSR J0737-3039, this duo is one of a kind. More commonly known as the “double-pulsar system”, it is the only two-pulsar system where we have observed both partners. Other binary-pulsar systems exist, consisting of a pulsar and, for example, a white dwarf or a (non-radiative) neutron star. However, astronomers find the double-pulsar system particularly valuable because it consists of two flashing beacons rather than one, and the more information they can glean to test their theories, the better.

Unfortunately, this article is currently only available in print, and Physics World isn’t a typical newsstand offering. Update: the editors have kindly let me repost the article here in PDF format for free download! You can also access all the content online by joining IoP (US$25 per year) and see everything they publish either through the Physics World website (which also has tons of free content) or the app, available on iTunes or Google Play.

I am overly proud of the headline, and the concepts I described in the article are very interesting. In brief, measurable properties of neutron star exteriors are independent of the particular physics going on inside. Since neutron stars are some of the most complex objects we know of — they are the density of an atomic nucleus, the mass of a star, and the size of a city on Earth — anything we can learn to help study them is a good thing. A few theorists figured out how to relate observable properties to each other, in particular three parameters labeled I, Q, and the “Love number” (named for a person, not the emotion). The I-Love-Q relations in combination with sophisticated neutron star observations could hopefully help us solve the deep mystery of what’s going inside an object that’s like nothing we can create in the lab.

(If you want some more technical information, here’s the main paper I drew on for background.)

Why are there three copies of each type of particle?

[ 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 mystery of particle generations

Why are there three almost identical copies of each particle of matter?

For Symmetry Magazine:

The Standard Model of particles and interactions is remarkably successful for a theory everyone knows is missing big pieces. It accounts for the everyday stuff we know like protons, neutrons, electrons and photons, and even exotic stuff like Higgs bosons and top quarks. But it isn’t complete; it doesn’t explain phenomena such as dark matter and dark energy.

The Standard Model is successful because it is a useful guide to the particles of matter we see. One convenient pattern that has proven valuable is generations. Each particle of matter seems to come in three different versions, differentiated only by mass.

Scientists wonder whether that pattern has a deeper explanation or if it’s just convenient for now, to be superseded by a deeper truth. [Read the rest at Symmetry]