Breakthrough in creation of gamma ray lasers that use antimatter

Superpowerful lasers for next-generation technologies are closer to existence.

  • A new study calculates how to create high-energy gamma rays.
  • Physicist Allen Mills proposes using liquid helium to make bubbles of positronium, a mixture with antimatter.
  • Gamma ray lasers can lead to new technologies in space propulsion, medical imaging and cancer treatment.


Scientists are closer to taming the most powerful light in the Universe. A physicist at the University of California has figured out how to make stable positronium atoms, which may lead to the creation of gamma ray lasers.

Gamma rays are the product of electromagnetic radiation that is caused by the radioactive decay of atomic nuclei. Harnessing these extremely bright (and usually very brief) lights, which have the highest photon energy, could lead to next-generation technologies. The highly penetrating gamma rays are shorter in wavelength than x-rays, and can be utilized for spacecraft propulsion, advanced medical imaging and treating cancers.

Creating a gamma ray laser requires manipulating positronium, a hydrogen-like atom that is a mixture of matter and antimatter — in particular, of electrons and their antiparticles known as positrons. The collision of a positron with an electron results in the production of gamma ray photons.

To make gamma-ray laser beams, the positronium atoms need to be in the same quantum state, called a Bose-Einstein condensate. The new study from professor Allen Mills of the UC Riverside Department of Physics and Astronomy, shows that hollow spherical bubbles filled with a positronium atom gas can be kept stable in liquid helium.

"My calculations show that a bubble in liquid helium containing a million atoms of positronium would have a number density six times that of ordinary air and would exist as a matter-antimatter Bose-Einstein condensate," said Mills.

Mills thinks helium would work as the stabilizing container because at extremely low temperatures, the gas would turn to liquid and actually repel positronium. This results from its negative affinity fo positronium and would cause bubbles to be created, which would be the source of the necessary Bose-Einstein condensates.

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Testing these ideas and actually configuring an antimatter beam to produce such bubbles in liquid helium is the next goal for the Positron laboratory at UC Riverside that Mills directs.

"Near term results of our experiments could be the observation of positronium tunneling through a graphene sheet, which is impervious to all ordinary matter atoms, including helium, as well as the formation of a positronium atom laser beam with possible quantum computing applications," explained the physicist.

Check out the new study in Physical Review A.

Professor Allen Mills of the UC Riverside Department of Physics and Astronomy.

Credit: I. Pittalwala, UC Riverside.

A still from the film "We Became Fragments" by Luisa Conlon , Lacy Roberts and Hanna Miller, part of the Global Oneness Project library.

Photo: Luisa Conlon , Lacy Roberts and Hanna Miller / Global Oneness Project
Sponsored by Charles Koch Foundation
  • Stories are at the heart of learning, writes Cleary Vaughan-Lee, Executive Director for the Global Oneness Project. They have always challenged us to think beyond ourselves, expanding our experience and revealing deep truths.
  • Vaughan-Lee explains 6 ways that storytelling can foster empathy and deliver powerful learning experiences.
  • Global Oneness Project is a free library of stories—containing short documentaries, photo essays, and essays—that each contain a companion lesson plan and learning activities for students so they can expand their experience of the world.
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Four philosophers who realized they were completely wrong about things

Philosophers like to present their works as if everything before it was wrong. Sometimes, they even say they have ended the need for more philosophy. So, what happens when somebody realizes they were mistaken?

Sartre and Wittgenstein realize they were mistaken. (Getty Images)
Culture & Religion

Sometimes philosophers are wrong and admitting that you could be wrong is a big part of being a real philosopher. While most philosophers make minor adjustments to their arguments to correct for mistakes, others make large shifts in their thinking. Here, we have four philosophers who went back on what they said earlier in often radical ways. 

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The history of using the Insurrection Act against Americans

Numerous U.S. Presidents invoked the Insurrection Act to to quell race and labor riots.

The army during riots in Washington, DC, after the assassination of civil rights activist Martin Luther King Jr., April 1968.

Photo by Michael Ochs Archives/Getty Images
Politics & Current Affairs
  • U.S. Presidents have invoked the Insurrection Act on numerous occasions.
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Experts are already predicting an 'active' 2020 hurricane season

It looks like a busy hurricane season ahead. Probably.

Image source: Shashank Sahay/unsplash
Surprising Science
  • Before the hurricane season even started in 2020, Arthur and Bertha had already blown through, and Cristobal may be brewing right now.
  • Weather forecasters see signs of a rough season ahead, with just a couple of reasons why maybe not.
  • Where's an El Niño when you need one?

Welcome to Hurricane Season 2020. 2020, of course, scoffs at this calendric event much as it has everything else that's normal — meteorologists have already used up the year's A and B storm names before we even got here. And while early storms don't necessarily mean a bruising season ahead, forecasters expect an active season this year. Maybe storms will blow away the murder hornets and 13-year locusts we had planned.

NOAA expects a busy season

According to NOAA's Climate Prediction Center, an agency of the National Weather Service, there's a 60 percent chance that we're embarking upon a season with more storms than normal. There does, however, remain a 30 percent it'll be normal. Better than usual? Unlikely: Just a 10 percent chance.

Where a normal hurricane season has an average of 12 named storms, 6 of which become hurricanes and 3 of which are major hurricanes, the Climate Prediction Center reckons we're on track for 13 to 29 storms, 6 to 10 of which will become hurricanes, and 3 to 6 of these will be category 3, 4, or 5, packing winds of 111 mph or higher.

What has forecasters concerned are two factors in particular.

This year's El Niño ("Little Boy") looks to be more of a La Niña ("Little Girl"). The two conditions are part of what's called the El Niño-Southern Oscillation (ENSO) cycle, which describes temperature fluctuations between the ocean and atmosphere in the east-central Equatorial Pacific. With an El Niño, waters in the Pacific are unusually warm, whereas a La Niña means unusually cool waters. NOAA says that an El Niño can suppress hurricane formation in the Atlantic, and this year that mitigating effect is unlikely to be present.

Second, current conditions in the Atlantic and Caribbean suggest a fertile hurricane environment:

  • The ocean there is warmer than usual.
  • There's reduced vertical wind shear.
  • Atlantic tropical trade winds are weak.
  • There have been strong West African monsoons this year.

Here's NOAA's video laying out their forecast:

But wait.

ArsTechnica spoke to hurricane scientist Phil Klotzbach, who agrees generally with NOAA, saying, "All in all, signs are certainly pointing towards an active season." Still, he notes a couple of signals that contradict that worrying outlook.

First off, Klotzbach notes that the surest sign of a rough hurricane season is when its earliest storms form in the deep tropics south of 25°N and east of the Lesser Antilles. "When you get storm formations here prior to June 1, it's typically a harbinger of an extremely active season." Fortunately, this year's hurricanes Arthur and Bertha, as well as the maybe-imminent Cristobal, formed outside this region. So there's that.

Second, Klotzbach notes that the correlation between early storm activity and a season's number of storms and intensities, is actually slightly negative. So while statistical connections aren't strongly predictive, there's at least some reason to think these early storms may augur an easy season ahead.

Image source: NOAA

Batten down the hatches early

If 2020's taught us anything, it's how to juggle multiple crises at once, and layering an active hurricane season on top of SARS-CoV-2 — not to mention everything else — poses a special challenge. Warns Treasury Secretary Wilbur Ross, "As Americans focus their attention on a safe and healthy reopening of our country, it remains critically important that we also remember to make the necessary preparations for the upcoming hurricane season." If, as many medical experts expect, we're forced back into quarantine by additional coronavirus waves, the oceanic waves slamming against our shores will best be met by storm preparations put in place in a less last-minute fashion than usual.

Ross adds, "Just as in years past, NOAA experts will stay ahead of developing hurricanes and tropical storms and provide the forecasts and warnings we depend on to stay safe."

Let's hope this, at least, can be counted on in this crazy year.

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