Traces of particles from the first second after the Big Bang

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Signs of neutrinos from the dawn of time, less than a second after the Big Bang

First unambiguous observation of the cosmic neutrino background

From Ars Technica:

The first 400,000 years after the Big Bang are inaccessible to us by using light; the material that filled the entire cosmos made it opaque. However, neutrinos interact very little with ordinary matter, so they could travel right through the opaque mess. Lots of these low-mass, fast-moving particles were formed in the first second after the Big Bang, so they could provide a sensitive probe of some of the very earliest moments in the Universe.

Unfortunately, these primordial neutrinos have never been detected directly, and they may have too little energy for us to ever detect them. But a new paper published in Physical Review Letters showed an unambiguous indirect detection using measurements of the cosmic microwave background light. This article marks the first clear measurement of the cosmic neutrino background, which is a significant confirmation of one of the major predictions of the Big Bang model. [Read the rest at Ars Technica…]

A multitude of faint and fluffy galaxies

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Scientists Discover Hundreds of Hidden Galaxies

The new type of faint, fluffy galaxy might help resolve a cosmological conundrum

For The Daily Beast:

When we think of galaxies, we tend to focus on the beautiful spirals, like the Milky Way, or possibly the huge elliptical galaxies. However, we know that a lot of galaxies are small, and those are harder to spot. In fact, astronomers have observed far fewer low-mass galaxies than predicted by theory, which has been a puzzle and a problem.

A new discovery might help with the answer. Astronomers using the Subaru telescope in Hawaii found 854 nearly invisible galaxies in the Coma Cluster. These hidden objects are very large—some are roughly the size of the Milky Way—but extremely low density. This new census is a notable increase in the population of the Coma Cluster, which is already a large galaxy cluster. It’s likely that other galaxy clusters could be hiding fluffy faint galaxies too. [Read more in The Daily Beast…]

No quantum foam seen in the cosmic beer glass

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Light from distant black holes doesn’t surf on waves of quantum foam

Strongest check yet on quantum gravity effects in astronomy turns up nothing

For Ars Technica:

Quantum gravity is notoriously slippery. While the Standard Model successfully describes three forces of nature, it doesn’t include gravity, so gravity still has no consistent quantum theory. To make matters worse, gravity is so weak that it’s difficult to probe at the sorts of energies where any minuscule quantum effects would pop out. However, some researchers predict that those tiny effects could accumulate over cosmological distances: light traveling from far-off quasars would be changed by the “quantum foam” of spacetime, producing blurry images in our telescopes—or even making objects seem to disappear.

A new report by E. S. Perlman and colleagues examines the disappearance hypothesis using gamma-ray data from quasars. In particular, they investigated a possibility suggested by the holographic principle, the idea that all the information in the cosmos can be encoded on the two-dimensional boundary that encloses it. Disappointingly for fans of quantum foam, the gamma ray data did not show any measurable fading or blurring of the quasars.

As the authors point out, these results don’t rule out anything general regarding quantum gravity, quantum foam, or the holographic principle. But they do provide the tightest constraint yet on cumulative effects of quantum foam on light traveling across the Universe. [Read the rest at Ars Technica…]

Listening to the sounds of the cosmos

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Last year, I went to a conference in Florida to hear — and in some cases meet — some of the leading thinkers in the study of gravitational waves. These waves are disturbances in the structure of spacetime itself, and could provide information about some exciting phenomena, if we can learn to detect them. The universe as heard in gravitational waves includes colliding black holes, white dwarfs locked in mutual orbits, exploding stars, and possibly chaotic disturbances from the very first instants after the Big Bang. This story marks one of my first big magazine articles, which I wrote for Smithsonian Air & Space magazine.

The Universe is Ringing

And astronomers are building observatories to listen to it

For Smithsonian Air & Space:

Think of it as a low hum, a rumble too deep to notice without special equipment. It permeates everything—from the emptiest spot in space to the densest cores of planets. Unlike sound, which requires air or some other material to carry it, this hum travels on the structure of space-time itself. It is the tremble caused by gravitational radiation, left over from the first moments after the Big Bang.

Gravitational waves were predicted in Albert Einstein’s 1916 theory of general relativity. Einstein postulated that the gravity of massive objects would bend or warp space-time and that their movements would send ripples through it, just as a ship moving through water creates a wake. Later observations supported his conception. [Read the rest at Air & Space….]

Looking to the heavens for neutrino masses

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Looking to the heavens for neutrino masses

From Symmetry Magazine:

Neutrinos may be the lightest of all the particles with mass, weighing in at a tiny fraction of the mass of an electron. And yet, because they are so abundant, they played a significant role in the evolution and growth of the biggest things in the universe: galaxy clusters, made up of hundreds or thousands of galaxies bound together by mutual gravity.

Thanks to this deep connection, scientists are using these giants to study the tiny particles that helped form them. In doing so, they may find out more about the fundamental forces that govern the universe. [Read the rest at Symmetry]

If we could only build one huge observatory….

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Q: Suppose we can only build one big telescope. Should we look for life among the stars or the origins of the universe?

I participated in an experts’ roundtable for Aeon Magazine, in which we were asked (more or less facetiously) what single project we would support to settle either questions about the very early universe or the existence of life elsewhere in the cosmos. Of course my real answer is that we should support all the science, because discovery isn’t about looking for one thing, but seeing what new things we can find. Throwing all our money at one big project might accomplish something, but it’s a bad way to do science. But anyway, taking the question for what it is — a fun exercise in wishing — here’s my answer, along with thoughts from Ross Andersen and Caleb Scharf.

The dark horse of the dark matter hunt

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The dark horse of the dark matter hunt

From Symmetry Magazine:

The ADMX experiment seems to be an exercise in contradictions.

Dark matter, the substance making up 85 percent of all the mass in the universe, is invisible. The goal of ADMX is to detect it by turning it into photons, particles of light. Dark matter was forged in the early universe, under conditions of extreme heat. ADMX, on the other hand, operates in extreme cold. Dark matter comprises most of the mass of a galaxy. To find it, ADMX will use sophisticated devices microscopic in size.

Scientists on ADMX—short for the Axion Dark Matter eXperiment—are searching for hypothetical particles called axions. The axion is a dark matter candidate that is also a bit of a dark horse, even as this esoteric branch of physics goes. [Read more in Symmetry Magazine]

This metal plate is perforated with holes, each of which lines up with a galaxy or quasar. The BOSS survey maps the position and distance to a huge number of galaxies using many masks such as this. [Credit: moi]

This metal plate is perforated with holes, each of which lines up with a galaxy or quasar. The BOSS survey maps the position and distance to a huge number of galaxies using many masks such as this. [Credit: moi]

Far from being invisible, black holes are among some of the brightest objects in the Universe. The black holes themselves aren’t emitting light, but the matter they draw in heats up and much of it shoots back out in powerful jets. When that happens, the black hole is known as a quasar, and it can be visible from billions of light-years away. For that reason, mapping the distribution of quasars can help cosmologists understand the expansion rate of the Universe in an earlier era — and constrain the behavior of dark energy. My latest story in The Daily Beast explains:

If dark energy will be the same in billions of years as it seems to be today, the future will be dark and empty, as galaxies continue to move apart from each other at ever-faster rates. If dark energy comes and goes, though, maybe the rate of expansion will slow down again. All of this is a long time from now—trillions of years after the death of the Sun—but we might see hints about it today. We hope to see signs of what is to come by looking at how dark energy behaves now, and how it has acted in the past. Similarly, if dark energy is stronger in some parts of the cosmos, then certain pockets of the Universe would grow faster than in others. That also has implications for how the future cosmos looks. [Read more…]

Using Black Holes to Measure Dark Energy, Like a BOSS

Now it can be told: I will be writing a weekly post for The Daily Beast (making me The Weekly Beast?), on space, astronomy, and such things. My first column is about inflation, and why it’s a big deal:

If you compare any two points on the night sky, their temperature as measured in microwave light is identical to a few millionths of a degree. That light, known as the cosmic microwave background, comes to us from nearly the beginning of the Universe, so it has been traveling for 13.8 billion years. Even with the expansion of the cosmos, two points on opposite sides of the sky were never in the same place, yet they have the same temperature… assuming the current rate of the expansion of the Universe has been roughly the same since the beginning.

But maybe it hasn’t. The cosmic temperature coincidence (which would be a great band name), along with several other annoying aspects of the Universe, led a group of researchers to propose the theory of inflation. [read more…]

The Daily Beast’s latest astronomy columnist is…me!

The BICEP2 telescope (foreground) with the South Pole Telescope (SPT) behind. [Credit: Steffen Richter (Harvard University)]

The BICEP2 telescope (foreground) with the South Pole Telescope (SPT) behind. [Credit: Steffen Richter (Harvard University)]

Today was an exciting and stimulating day: the BICEP2 collaboration announced the first measurement of the cosmic microwave background that might tell us whether or not inflation happened. Inflation is the hypothetical rapid expansion of the Universe during its first instants, which explains a lot about why the cosmos appears the way it does. However, data on inflation itself, as opposed to its side-effects, are hard to come by. This new observation could help resolve that…assuming we can figure out why some of its aspects don’t agree with prior observations.

While they do not constitute a direct detection of either primordial gravitational waves (the distortions causing the light polarization) or inflation, the BICEP2 results could provide the best evidence for both that could not be easily explained away by other theories. This observation cannot be the end of the story, however. The measurement of polarization is significantly larger that what is seen in the results of prior observations in a way that cannot be immediately dismissed. Whether the problems are with the interpretation and analysis of the BICEP2 data, or if something more subtle is at work, remains to be seen. [Read more….]

New data offer a peek into the Universe’s first instants