Blowing up high-mass stars with low-mass neutrinos

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Low-mass particles that make high-mass stars go boom

Simulations are key to showing how neutrinos help stars go supernova.

For Symmetry Magazine:

When some stars much more massive than the sun reach the end of their lives, they explode in a supernova, fusing lighter atoms into heavier ones and dispersing the products across space—some of which became part of our bodies. As Joni Mitchell wrote and Crosby Stills Nash & Young famously sang, “We are stardust, we are golden, we are billion-year-old carbon.”

However, knowing this and understanding all the physics involved are two different things. We can’t make a true supernova in the lab or study one up close, even if we wanted to. For that reason, computer simulations are the best tool scientists have. Researchers program equations that govern the behavior of the ingredients inside the core of a star to see how they behave and whether the outcomes reproduce behavior we see in real supernovae. There are many ingredients, which makes the simulations extraordinarily complicated—but one type of particle could ultimately drive supernova explosion: the humble neutrino. [Read the rest at Symmetry Magazine]

Everything is a particle, but what does that mean?!

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What is a “particle”?

Quantum physics says everything is made of particles, but what does that actually mean?

For Symmetry Magazine:

“Is he a dot or is he a speck? When he’s underwater, does he get wet? Or does the water get him instead? Nobody knows.” —They Might Be Giants, “Particle Man”

We learn in school that matter is made of atoms and that atoms are made of smaller ingredients: protons, neutrons and electrons. Protons and neutrons are made of quarks, but electrons aren’t. As far as we can tell, quarks and electrons are fundamental particles, not built out of anything smaller.

It’s one thing to say everything is made of particles, but what is a particle? And what does it mean to say a particle is “fundamental”? What are particles made of, if they aren’t built out of smaller units? [Read the rest at Symmetry Magazine]

 

Are neutrinos their own worst enemies?

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EXO-200 resumes its underground quest

The upgraded experiment aims to discover if neutrinos are their own antiparticles

For Symmetry Magazine:

Science is often about serendipity: being open to new results, looking for the unexpected.

The dark side of serendipity is sheer bad luck, which is what put the Enriched Xenon Observatory experiment, or EXO-200, on hiatus for almost two years.

Accidents at the Department of Energy’s underground Waste Isolation Pilot Project (WIPP) facility near Carlsbad, New Mexico, kept researchers from continuing their search for signs of neutrinos and their antimatter pairs. Designed as storage for nuclear waste, the site had both a fire and a release of radiation in early 2014 in a distant part of the facility from where the experiment is housed. No one at the site was injured. Nonetheless, the accidents, and the subsequent efforts of repair and remediation, resulted in a nearly two-year suspension of the EXO-200 effort.

Things are looking up now, though: Repairs to the affected area of the site are complete, new safety measures are in place, and scientists are back at work in their separate area of the site, where the experiment is once again collecting data. [Read the rest at Symmetry Magazine….]

The GUTsy effort to unify the quantum forces

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A GUT feeling about physics

Scientists want to connect the fundamental forces of nature in one Grand Unified Theory

For Symmetry Magazine:

The 1970s were a heady time in particle physics. New accelerators in the United States and Europe turned up unexpected particles that theorists tried to explain, and theorists in turn predicted new particles for experiments to hunt. The result was the Standard Model of particles and interactions, a theory that is essentially a catalog of the fundamental bits of matter and the forces governing them.

While that Standard Model is a very good description of the subatomic world, some important aspects—such as particle masses—come out of experiments rather than theory.

“If you write down the Standard Model, quite frankly it’s a mess,” says John Ellis, a particle physicist at King’s College London. “You’ve got a whole bunch of parameters, and they all look arbitrary. You can’t convince me that’s the final theory!” [Read the rest at Symmetry Magazine…]

Some light reading about light

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As I mentioned before, I’m branching out a bit and writing some listicles for Symmetry Magazine this year. The first covered gravity, and the second covers… light!

Eight things you might not know about light

Light is all around us, but how much do you really know about the photons speeding past you?

For Symmetry Magazine:

1. Photons can produce shock waves in water or air, similar to sonic booms.

Nothing can travel faster than the speed of light in a vacuum. However, light slows down in air, water, glass and other materials as photons interact with atoms, which has some interesting consequences.

The highest-energy gamma rays from space hit Earth’s atmosphere moving faster than the speed of light in air. These photons produce shock waves in the air, much like a sonic boom, but the effect is to make more photons instead of sound. Observatories like VERITAS in Arizona look for those secondary photons, which are known as Cherenkov radiation. Nuclear reactors also exhibit Cherenkov light in the water surrounding the nuclear fuel. [Read the rest at Symmetry Magazine…]

Some heavy facts about gravity

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I’m not generally the type of writer who makes listicles, but I’m producing a few for Symmetry Magazine this year. The first covers the OG of fundamental forces: gravity!

Six weighty facts about gravity

Perplexed by gravity? Don’t let it get you down

For Symmetry Magazine:

Gravity: we barely ever think about it, at least until we slip on ice or stumble on the stairs. To many ancient thinkers, gravity wasn’t even a force—it was just the natural tendency of objects to sink toward the center of Earth, while planets were subject to other, unrelated laws.

Of course, we now know that gravity does far more than make things fall down. It governs the motion of planets around the Sun, holds galaxies together and determines the structure of the universe itself. We also recognize that gravity is one of the four fundamental forces of nature, along with electromagnetism, the weak force and the strong force.

The modern theory of gravity—Einstein’s general theory of relativity—is one of the most successful theories we have. At the same time, we still don’t know everything about gravity, including the exact way it fits in with the other fundamental forces. But here are six weighty facts we do know about gravity. [Read the rest at Symmetry Magazine]

A new detector in the hunt for particles and the origin of matter

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Belle II and the matter of antimatter

Go inside the new detector looking for why we’re here

For Symmetry Magazine:

We live in a world full of matter: stars made of matter, planets made of matter, pizza made of matter. But why is there pizza made of matter rather than pizza made of antimatter or, indeed, no pizza at all?

In the first split-second after the big bang, the universe made a smidgen more matter than antimatter. Instead of matter and antimatter annihilating one another and leaving an empty, cold universe, we ended up with a surplus of stuff. Now scientists need the most sensitive detectors and mountains of experimental data to understand where that imbalance comes from.

Belle II is one of those detectors that will look for differences between matter and antimatter to explain why we’re here at all. Currently under construction, the 7.5-meter-long detector will be installed in the newly recommissioned SuperKEKB particle accelerator located in Tsukuba, Japan. SuperKEKB runs beams of electrons and positrons (the antimatter version of electrons) into each other at close to the speed of light, and Belle II—once it is fully operational in 2018—will analyze the detritus of the collisions. [Read the rest at Symmetry Magazine…]

BICEP3: Revenge of the telescope

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Dusting for the fingerprint of inflation with BICEP3

A new experiment at the South Pole picks up where BICEP2 left off

For Symmetry Magazine:

When researchers with the BICEP2 experiment announced they had seen the first strong evidence for cosmic inflation, it was front-page news around the world. Inflation is the extremely rapid expansion of space-time during its first split second of existence, proposed to explain a number of puzzling properties of the universe, making the BICEP2 results a really big deal. Over the following months, though, the excitement evaporated: After combining their data with other experiments, the BICEP2 team showed that most or all of the signal attributed to inflation was likely produced by galactic dust inside the Milky Way.

But traces of inflation could still be hiding in the data, and that’s why scientists haven’t given up yet. BICEP3, the upgraded version of BICEP2, began collecting data yesterday. The first observations using the fully updated equipment will run through November. [Read the rest at Symmetry Magazine]

A net for neutrinos at the bottom of the sea

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Casting a net for neutrinos

The KM3NeT experiment will catch the elusive particles using the Mediterranean Sea

For Symmetry Magazine:

Like ordinary telescopes, KM3NeT operates in darkness—but there the resemblance ends. The Km3 Neutrino Telescope (where km3 means a cubic kilometer) is a suite of detectors that sits at the pitch-black bottom of the Mediterranean Sea, 3.5 kilometers below the waves and strong currents of the surface.

KM3NeT needs this absolute night to see the faint amount of light from ghostly neutrinos striking water molecules. Neutrinos pass through most material as though it weren’t there, which is why detectors need to be so big to spot them—more volume means more chances to see a neutrino interact. When completed, KM3NeT will be the largest neutrino detector in the world, made of about 1.3 trillion gallons of seawater. [Read the rest at Symmetry Magazine]

Why are neutrino masses so tiny?

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Neutrinos on a seesaw

A possible explanation for the lightness of neutrinos could help answer some big questions about the universe.

For Symmetry Magazine:

Mass is a fundamental property of matter, but there’s still a lot about it we don’t understand—especially when it comes to the strangely tiny masses of neutrinos.

An idea called the seesaw mechanism proposes a way to explain the masses of these curious particles. If shown to be correct, it could help us understand a great deal about the nature of fundamental forces and—maybe—why there’s more matter than antimatter in the universe today. [Read the rest at Symmetry Magazine….]