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]

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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…)

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]

The search for a “theory of everything”

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All four one and one for all

A theory of everything would unite the four forces of nature, but is such a thing possible?

For Symmetry Magazine:

Over the centuries, physicists have made giant strides in understanding and predicting the physical world by connecting phenomena that look very different on the surface.

One of the great success stories in physics is the unification of electricity and magnetism into the electromagnetic force in the 19th century. Experiments showed that electrical currents could deflect magnetic compass needles and that moving magnets could produce currents.

Then physicists linked another force, the weak force, with that electromagnetic force, forming a theory of electroweak interactions. Some physicists think the logical next step is merging all four fundamental forces—gravity, electromagnetism, the weak force and the strong force—into a single mathematical framework: a theory of everything.

Those four fundamental forces of nature are radically different in strength and behavior. And while reality has cooperated with the human habit of finding patterns so far, creating a theory of everything is perhaps the most difficult endeavor in physics. [Read the rest at Symmetry]

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]