I’m at GeekGirlCon this weekend, so I’m busy with non-writing activities as part of the DIY Science Zone. Thanks to our Fearless Leader Dr. “Nick Fury” Rubidium for putting our part of the event together!
Where Nature Hides the Darkest Mystery of All (Nautilus): Even though there’s no solid barrier, the event horizon of a black hole provides a boundary through which we can’t see or probe. That leads to a troubling idea: will we ever know what’s really inside that event horizon? Is there any way to learn about the interior by indirect measurements?
Black hole hair and the dark energy problem (Galileo’s Pendulum): Building off that article, what happens if our standard theory of gravity is modified? That’s not an entirely crazy idea: several modifications to general relativity have been proposed, inspired by inflation (the rapid expansion during the cosmos’ earliest moments) or dark energy. A recent paper examined that idea, and here’s my take.
Strongly magnetic pulsar could explain anomalous supernovas (Ars Technica): Some supernovas are particularly bright, especially some from the early Universe. These, known as “pair-instability” supernovas, are the explosion of very massive stars made of nearly pure hydrogen and helium. However, some of these super-luminous supernovas don’t quite fit that profile, including being too close. A new set of observations may show they are actually driven by a magnetar, a highly magnetized pulsar.
Gravitational waves show deficit in black hole collisions (Ars Technica): Mergers of supermassive black holes should happen frequently enough to produce a bath of gravitational radiation permeating the cosmos. While that gravitational wave background (GWB) possesses wavelengths too large for ground-based detectors like LIGO, astronomers realized it might be visible in the fluctuations of light from pulsars. However, they didn’t see what they expected, leading to the big question: why not?
The center of the Milky Way lies at the upper left of this image from the 2MASS survey of galaxies. [Credit: 2MASS/G. Kopan, R. Hurt]
My black holes class and other responsibilities ate my brain the last two weeks, so I forgot to post a “week in review” last week. So, here’s the highlights from the last two weeks. If it’s more heavily weighted toward black holes even than usual, that’s hardly surprising.
Of fire and ice and Harlow Shapley (Galileo’s Pendulum): In 1918, a poet named Robert Frost met an astronomer named Harlow Shapley. The result, according to Shapley, was “Fire and Ice”. Most people probably don’t remember who Shapley was anymore, but in his day he was one of the most prominent astronomers, helping to map the galaxy and measuring its size.
Portrait of a black hole, part 1 (Galileo’s Pendulum): When trying to understand the curved four-dimensional spacetime of gravity, we have to resort to metaphor and simplified pictures. Here’s my attempt to describe spacetime around a (non-rotating) black hole using a dynamic analogy: a flowing current, against which objects must move.
A scientific love affair (Galileo’s Pendulum): Like many (most?) little kids, dinosaurs captured my imagination, sparking me to think about science for the first time. However, black holes, pulsars, and other products of extreme gravity inspired me in a different direction when I was in sixth grade. Here’s a partial story of my love affair with gravity.
The 2013 Nobel Prize in physics: the Higgs boson (Galileo’s Pendulum): The 2013 Nobel Prize was awarded this week to François Englert and Peter Higgs for the theoretical prediction of what is now known as the Higgs boson. This post celebrates that award, but also delves into how the Nobel Prize fails. In promoting the “lone (male) genius” view of science and thereby failing to acknowledge contributions by the others who deserve recognition for the Higgs boson, the Nobel Prize does a disservice to that which it seeks to honor. Bonus: what the Nobel Prize has to do with the leg lamp from A Christmas Story.
Measuring a superconducting qubit by manipulating its environment (Ars Technica): Now for something completely different! Quantum systems are complicated, involving interactions between the objects we want to study, the environment of those objects, and our measuring apparatus. A new experiment shows a way of measuring an object’s properties indirectly by performing environmental measurements instead. The result is a picture of a superconducting quantum bit (or qubit) as it evolves in time.
I spent much of the week sick, but that doesn’t stop me. I care about you, people.
All black holes, great and small (Galileo’s Pendulum): As my regular readers have probably figured out, I love black holes. I could probably find an excuse to write about them most days. So, why not take an online class from me and learn about black holes? The class begins this Tuesday (October 1), and runs for four one-hour sessions. Sign up today!
A Holographic Big Bang: Did the universe start with a five-dimensional black hole? (Slate): Much as I love black holes, however, I cast a skeptical eye on a new paper proposing that the Big Bang had an event horizon. This Slate piece examines what we mean by the “Big Bang model” (which isn’t quite how it’s often described), and the reasons why this five-dimensional theory probably won’t solve the mystery of our Universe’s origins.
Scientific grumpfiness and open-mindedness (Galileo’s Pendulum): All three pieces I’ve written for Slate thus far, in addition to a number of other articles published elsewhere, are critical responses to scientific reporting. Generally, I find myself on the opposite side to those who promote radical new theories, which makes me worry sometimes that I’m just a naysayer with no positive commentary to make. Here’s my examination of that worry. (Yes, it’s a bit meta, I suppose.)
Pulsar’s magnetic field strong enough to clean up after nuclear explosion (Ars Technica): While pulsars are all fast-spinning objects, some are extremely so, rotating hundreds or thousands of times each second. A new observation caught one of these pulsars in the act of feeding off material from a companion star, lending strong support to the theory of how they spin so fast. Bonus: runaway nuclear explosions! on the surface of a dead star! Who needs science fiction?
Snobbish photons forced to pair up and get heavy (Ars Technica): Photons don’t usually interact in the usual sense that matter particles do. Researchers produced a weird medium by pumping a diffuse gas of rubidium atoms with laser light until they puffed up. The result: the interactions between the atoms made an environment where photons have an effective mass (!) and attract each other, forming pairs. Beyond being really cool, this could have all sorts of applications in quantum logic and even “photon materials”.
And just because I can, here’s Cookie Monster playing with his Newton’s cradle again.
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.
Writer/editor David Manly posed a series of questions to scientists and writers, soliciting short responses on topics of broad interest. Those interviewed were shark researcher David Schiffman, paleontology writer/sauropod snogger Brian Switek, and me. If you want to know who would win an arm-wrestling contest between a human and a Tyrannosaurus, or how we know black holes exist if we can’t see them, this post is for you.
No question: supermassive black holes get a lot of the glory, thanks to their obvious presence at the centers of many galaxies. However, stars more than 20 times the mass of our Sun leave behind smaller, stellar-mass black holes after their violent supernova deaths. Despite this model’s wide acceptance, astronomers have only identified about 50 stellar-mass black holes in the Milky Way to date, but there must be many more lurking. A new study may have revealed why: the black holes are shrouded by a thick donut of gas that blocks much of their X-ray light from reaching us.
J. M. Corral-Santana and colleagues based this hypothesis on a detailed study of a relatively faint, fluctuating X-ray source in the Milky Way. Their observations in X-ray and visible light revealed the signs of a binary system: an ordinary star in orbit around a black hole, similar to other systems, but with some key differences. For one, the star and black hole were so close together that the orbital period of the system was only 2.8 hours. For another, the matter being drawn off the star was obscuring the black hole when viewed from Earth. The authors hypothesized that many other black holes may be similarly hidden, and future searches should take that possibility into account. [Read more…]
Any core-collapse supernova—the explosion of a massive star—is by nature powerful, destructive, and rare. The really dramatic supernovas have the extra effect of exploding in a non-spherical way, beaming a lot of their matter and energy along an axis. When Earth is aligned with those beams, we see the supernova as a gamma ray burst (GRB), the brightest of which can be seen from billions of light-years away. (As the name suggests, these events are exceptionally bright in gamma ray light. In fact, they were first discovered by spy satellites monitoring for illicit nuclear tests—which are also marked by heavy gamma ray emission.) Observations of a supernova remnant in our galaxy strongly hint both that it was a GRB, and that it harbors a black hole at its center. That would mean the supernova is the only known GRB in our galaxy, and its black hole is the youngest known—a wonderful double discovery.
While stars like our Sun go gently into that good night, stars more than 25 times more massive explode in violent supernovae. Since stars that big are rare, their explosions are too, so astronomers typically have to do forensic work on supernova remnants in our galaxy. One particular remnant is one the brightest X- and gamma-ray sources around, marking it as a relatively recent explosion. By studying the remnant, astronomers have determined it likely harbors the youngest black hole in the Milky Way, and the original explosion may have been extremely energetic. [Read more…]
The term “quasar” describes a behavior rather than an object: when a supermassive black hole (SMBH) at the center of a galaxy gorges on gas, the infalling matter produces a lot of light. While most galaxies are known to have SMBHs, not all of those exhibit quasar behavior. Similarly, black holes created from the deaths of massive stars—the stellar mass black holes—don’t generally consume matter at a rapid rate. However, a few do, and those are known as microquasars. Four microquasar candidates have been found in the Milky Way, and now one has been located in M31, the Andromeda Galaxy.
Unlike microquasars in the Milky Way, those in other galaxies potentially provide an unimpeded view of the black hole accretion process. This will allow astronomers to test whether microquasars are miniature versions of their supermassive cousins, and measure the accretion mechanism in unprecedented detail. Since the nearest “regular” quasars are much farther away than M31, a nearby microquasar provides a beautiful target for observations of how black holes beam infalling matter into jets, and the specific processes are by which they make their intense light. [Read more…]
Yesterday (November 10, 2012) I spoke about black holes at the Richmond Public Library. For those who couldn’t make it, or who were there but want more information, here’s the essence of the talk, along with the relevant images that formed my slides. Please leave any questions you have in the comments, and thanks to everyone who came out (despite the insane marathon-related traffic)!
Discussions of black holes fall into two distinct categories. The first is the sexy string theory/quantum gravity/Stephen Hawking category, all about time warps, wormholes, extra dimensions, Bekenstein entropy, and baby universes; the second discusses the real black holes discovered in our galaxy and beyond. While the sexy stuff is a lot of fun to talk about, that’s not what I discussed: it’s speculative, and at the present time impossible to test. (Some of it by its very nature is impossible to test, since we can’t get access to the region inside a black hole. More on that shortly.) However, I think real astronomical black holes are just as interesting, and over the last several decades astronomers have realized how important they are in shaping the galaxies they inhabit. Continue reading →
Did I mention the talk is informal? It’s an informal talk.
Today—November 10, 2012—I will be speaking about black holes at the Richmond Public Library. The talk is free and for all ages (though I think older children may appreciate the topic more). No prior knowledge is assumed, so bring your questions and curiosity!