Forging dark matter in the Big Bang

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The origins of dark matter

Theorists think dark matter was forged in the hot aftermath of the Big Bang

For Symmetry Magazine:

Transitions are everywhere we look. Water freezes, melts, or boils; chemical bonds break and form to make new substances out of different arrangements of atoms. The universe itself went through major transitions in early times. New particles were created and destroyed continually until things cooled enough to let them survive.

Those particles include ones we know about, such as the Higgs boson or the top quark. But they could also include dark matter, invisible particles which we presently know only because of their gravitational effects.

In cosmic terms, dark matter particles could be a “thermal relic,” forged in the hot early universe and then left behind during the transitions to more moderate later eras. One of these transitions, known as “freeze-out,” changed the nature of the whole universe. [Read the rest at Symmetry Magazine]

The search for magnetic monopoles, the truest north

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The hunt for the truest north

Many theories predict the existence of magnetic monopoles, but experiments have yet to see them

For Symmetry Magazine:

If you chop a magnet in half, you end up with two smaller magnets. Both the original and the new magnets have “north” and “south” poles.

But what if single north and south poles exist, just like positive and negative electric charges? These hypothetical beasts, known as “magnetic monopoles,” are an important prediction in several theories.

Like an electron, a magnetic monopole would be a fundamental particle. Nobody has seen one yet, but many—maybe even most—physicists would say monopoles probably exist. (Read the rest at Symmetry Magazine…)

There (to an asteroid) and back again: a robot’s journey

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This Thursday, the OSIRIS-REx robotic probe will launch from Cape Canaveral in Florida, destined for asteroid Bennu. I can’t ride with the probe, but I’m doing the next best thing: going to Florida to watch the launch, alongside scientists involved in the project. Here’s a preview, written for New Scientist:

NASA probe about to leave for asteroid Bennu and bring bits home

For New Scientist:

Bennu or bust. On 8 September, the OSIRIS-REx probe will leave Earth for the asteroid Bennu, and will return with souvenirs: up to 2 kilograms of material from its surface.

OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer) is the latest in a string of sample return missions, following the Stardust mission to the comet Wild 2 and the Hayabusa mission to asteroid Itokawa. Both of those missions hit hurdles, and neither brought more than a few grains of material back to Earth.

OSIRIS-Rex will pioneer a new and ambitious technique for gathering samples: a robotic arm equipped with a vacuum cleaner. [Read the rest at The New Scientist]

Confused about the Big Bang? Start here

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The Big Bang is the central concept in cosmology — the study of the whole universe — but it can be confusing to a lot of people. In fact, it’s a little unfair: some of the confusion comes from us cosmologists. In my latest for Symmetry, I try to sift out some of the important concepts and hopefully clear up some of the confusion.

Five facts about the Big Bang

It’s the cornerstone of cosmology, but what is it all about?

For Symmetry Magazine:

Astronomers Edwin Hubble and Milton Humason in the early 20th century discovered that galaxies are moving away from the Milky Way. More to the point: Every galaxy is moving away from every other galaxy on average, which means the whole universe is expanding. In the past, then, the whole cosmos must have been much smaller, hotter and denser.

That description, known as the Big Bang model, has stood up against new discoveries and competing theories for the better part of a century. So what is this “Big Bang” thing all about? [Read the rest at Symmetry Magazine]

Information ain’t no good if you can’t get to it

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The most important website in particle physics

The first website to be hosted in the US has grown to be an invaluable hub for open science

For Symmetry Magazine:

With tens of thousands of particle physicists working in the world today, the biggest challenge a researcher can have is keeping track of what everyone else is doing. The articles they write, the collaborations they form, the experiments they run—all of those things are part of being current. After all, high-energy particle physics is a big enterprise, not the province of a few isolated people working out of basement laboratories.

Particle physicists have a tool that helps them with that. The INSPIRE database allows scientists to search for published papers by topic, author, scholarly journal, what previous papers the authors cited and which newer papers have used it as a reference.

“I don’t know any other discipline with such a central tool as INSPIRE,” says Sünje Dallmeier-Tiessen, an information scientist at CERN who manages INSPIRE’s open-access initiative. If you’re a high-energy physicist, “everything that relates to your daily work-life, you can find there.” [Read the rest at Symmetry Magazine]

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]

Finding all the matter in the cosmos — even the invisible stuff

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“Weak Lensing” Helps Astronomers Map the Mass of the Universe

By making galaxies a little bit brighter, it points the way to elusive galaxies and lets us detect that most mysterious of substances: dark matter

For Smithsonian Magazine:

In ordinary visible light, this cluster of galaxies doesn’t look like much. There are bigger clusters with larger and more dramatic-looking galaxies in them. But there’s more to this image than galaxies, even in visible light. The gravity from the cluster magnifies and distorts light passing near it, and mapping that distortion reveals something about a substance ordinarily hidden from us: dark matter.

This collection of galaxies is famously called the “Bullet Cluster,” and the dark matter inside it was detected through a method called “weak gravitational lensing.” By tracking distortions in light as it passes through the cluster, astronomers can create a sort of topographical map of the mass in the cluster, where the “hills” are places of strong gravity and “valleys” are places of weak gravity. The reason dark matter—the mysterious substance that makes up most of the mass in the universe—is so hard to study is because it doesn’t emit or absorb light. But it does have gravity, and thus it shows up in a topographical map of this kind.

The Bullet Cluster is one of the best places to see the effects of dark matter, but it’s only one object. Much of the real power of weak gravitational lensing involves looking at thousands or millions of galaxies covering large patches of the sky. [Read the rest at Smithsonian Magazine]