Meet the glueball, the missing Standard Model particle

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Glueballs are the missing frontier of the Standard Model

There should be particles made entirely of gluons, but we don’t know how to find them

For Ars Technica:

The discovery of the Higgs boson was rightfully heralded as a triumph of particle physics, one that brought completion to the Standard Model, the collection of theories that describes particles and their interactions. Lost in the excitement, however, was the fact that we’re still missing a piece from the Standard Model—another type of particle that doesn’t resemble any other we’ve yet seen.

The particle is a glueball, but its goofy name doesn’t express how interesting it is. Glueballs are unique in that they don’t contain any matter at all: they have no quarks or electrons or neutrinos. Instead, they are made entirely of gluons, which are the particles that bind quarks together inside protons, neutrons, and related objects.

Particle physicists are sure they exist, but everything else about them is complicated, to say the least. Like so many other exotic particles (including the Higgs), glueballs are very unstable, decaying quickly into other, less massive particles. We don’t have any ideas about their masses, however, which is obviously kind of important to know if you want to find them. We also don’t know exactly how they decay, making it hard to know exactly how we’ll identify them in experiments. [Read the rest at Ars Technica….]

Can we recognize life if we see it on other worlds?

Back in June, I traveled to a remote lake in British Columbia to visit a NASA research site. That trip resulted in a long article I wrote for Mosaic, which roamed over a wide range of topics: what a Canadian lake has to do with life on Mars, the difficulty of identifying life on other worlds (such as Saturn’s moon Enceladus), and whether the particular chemistry of life as we know it is the only possibility. You know, simple topics with easy science.

As exotic environments go, Pavilion Lake in British Columbia is rather ordinary. Certainly it’s remote – the closest major city is Vancouver, a long drive away over the mountains. The closest towns are light dustings of houses over the dry slopes, and the road winds for dozens of kilometres of empty desert country between them. The lake itself lies along a paved highway, and from the road it doesn’t look different to any other modestly sized mountain lake in western North America.

But below the surface, the bottom of Pavilion Lake is dotted with something resembling coral reefs: domes and cones and weird shapes much like artichokes. These are not corals, though, which are colonies of tiny animals: they are rock formations called microbialites, made by and coated in cyanobacteria. Sometimes misleadingly referred to as ‘blue-green algae’, these bacteria probably even made the rocks they live on, absorbing nutrients from the water and leaving stone behind. Like plants, they live on sunlight, and they thrive in shallow waters down the steep underwater slope to the point where sunlight fades to gloom.

They are the reason for NASA’s interest, and my visit. The people I’ve come here to see have even bigger things in mind. They want to know what the rare formations in Pavilion Lake might tell us about the origins of life on Earth, life on other worlds and, indeed, what life is, exactly. [Read the rest at Mosaic….]

Thanks to Darlene Lim, Donnie Reid, camp chef Shane Smitna (who let me join the research crew for meals), Tyler Mackey, Frances Rivera-Hernandez, Allyson Brady, Dale Anderson, Zena Cardman, David Lynn, and John Chaput. (Apologies to Dale and Zena for not having the space to include some quotes from you. Even with 3000 words to work with, I couldn’t fit half of what I needed into the story!)

Special thanks and appreciation to the Ts’kw’aylaxw First Nation, on whose land Pavilion Lake sits.

A tribute to a great African-American planetary scientist

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Meet Claudia Alexander, NASA Badass Who Never Got Her Due

In a field dominated by white men, Claudia Alexander was a pioneer

For The Daily Beast:

Comet 67P/Churyumov—Gerasimenko is a tiny world of ice and rock, just 5 kilometers long. The comet is shaped vaguely like a rubber duck, with steep cliffs and other prominent features that stand much taller in relation to the size of the world. One of remarkable features is a twin set of sharp “horns” on the head of the rubber duck, known now as C. Alexander Gate.

Claudia Alexander served as project scientist for the Rosetta mission, which is orbiting Comet 67P. Until her death in July, she helped lead the United States side of the project, coordinating the various scientific and engineering aspects of the mission. Last week, her colleagues named the C. Alexander Gate in her honor and memory, with her European Space Agency counterpart Matt Taylor making the announcement.

Alexander is the first, and so far only, African-American woman to achieve such a prestigious position on a space mission, and she did it twice: once for the Galileo spacecraft to Jupiter and again for the Rosetta probe to Comet 67P. In fact, she was also the youngest ever appointed when she was picked at age 40 to be the final project scientist for the Galileo mission in 2000. [Read the rest at The Daily Beast….]

How standard are “standard candles”?

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Not-so-standard candles

From Physics World:

The story is already legendary. In the late 1980s and early 1990s, two groups of rival researchers set out to measure the deceleration of the expanding universe. These groups often used the same observatory, sometimes even using the same telescope on consecutive nights. And they both found the same thing, publishing their results at roughly the same time in 1998–1999: the expansion of space–time isn’t slowing down at all. In fact, it’s getting faster. The leaders of those collaborations – Saul Perlmutter and Brian Schmidt – along with Adam Riess of the latter’s group, won the Nobel Prize for Physics in 2011 for this discovery. The implication of the result was that the universe consists not only of visible matter and dark matter, but also a gravitationally repulsive substance. Known as dark energy, the nature of this weird stuff remains as mysterious today as when it was first discovered.

Both groups used certain kinds of exploding stars called type Ia supernovae for their measurements. These supernovae brighten and fade in very similar ways and the current thinking is that this is because they have a common source: the explosion of either one or two white dwarfs, which are the stellar remnants of small-to-medium-mass stars such as the Sun. This consistent brightness allows astronomers to determine how far away the object was when the light left it and for that reason, type Ia supernovae are known as “standard candles” – reliable light- houses in the measurement of cosmic distances.

Or so we all thought.

The rest of this story is in the print edition of Physics World, which you can subscribe to through membership in the Institute of Physics, which costs £15, €20, or $25 per year. You can join by clicking here. You can also get a nice mobile- and tablet-formatted version of the story using the Physics World app, available in the Google Play and iTunes stores. However, if you just want to read the rest of this article, Physics World has kindly allowed me to offer it to you as a PDF download, which looks exactly like the printed version!