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Lasers could cut lifespan of nuclear waste from "a million years to 30 minutes," says Nobel laureate

Physicist plans to karate-chop them with super-fast blasts of light.

(Oleksiy Mark/Borys Magierowski/Shutterstock/Big Think)
  • Gérard Mourou has already won a Nobel for his work with fast laser pulses.
  • If he gets pulses 10,000 times faster, he says he can modify waste on an atomic level.
  • If no solution is found, we're already stuck with some 22,000 cubic meters of long-lasting hazardous waste.

Whatever one thinks of nuclear energy, the process results in tons of radioactive, toxic waste no one quite knows what to do with. As a result, it's tucked away as safely as possible in underground storage areas where it's meant to remain a long, long time: The worst of it, uranium 235 and plutonium 239, have a half life of 24,000 years. That's the reason eyebrows were raised in Europe — where more countries depend on nuclear energy than anywhere else — when physicist Gérard Mourou mentioned in his wide-ranging Nobel acceptance speech that lasers could cut the lifespan of nuclear waste from "a million years to 30 minutes," as he put it in a followup interview with The Conversation.

Who is Gérard Mourou?

Mourou was the co-recipient of his Nobel with Donna Strickland for their development of Chirped Pulse Amplification (CPA) at the University of Rochester. In his speech, he referred to his "passion for extreme light."

CPA produces high-intensity, super-short optical pulses that pack a tremendous amount of power. Mourou's and Strickland's goal was to develop a means of making highly accurate cuts useful in medical and industrial settings.

It turns out CPA has another benefit, too, that's just as important. Its attosecond pulses are so quick that they shine a light on otherwise non-observable, ultra-fast events such as those inside individual atoms and in chemical reactions. This capability is what Mourou hopes give CPA a chance of neutralizing nuclear waste, and he's actively working out a way to make this happen in conjunction with Toshiki Tajima of UC Irvine. As Mourou explains to The Conversation:

"Take the nucleus of an atom. It is made up of protons and neutrons. If we add or take away a neutron, it changes absolutely everything. It is no longer the same atom, and its properties will completely change. The lifespan of nuclear waste is fundamentally changed, and we could cut this from a million years to 30 minutes!

We are already able to irradiate large quantities of material in one go with a high-power laser, so the technique is perfectly applicable and, in theory, nothing prevents us from scaling it up to an industrial level. This is the project that I am launching in partnership with the Alternative Energies and Atomic Energy Commission, or CEA, in France. We think that in 10 or 15 years' time we will have something we can demonstrate. This is what really allows me to dream, thinking of all the future applications of our invention."

While 15 years may seem a long time, when you're dealing with the half-life of nuclear waste, it's a blink of an eye.

Nuclear waste in Europe

Although nuclear energy struggles for acceptance as an energy source in the U.S. after a series of disturbing incidents and the emergence of alternative sources such as solar and wind energy, many European nations have embraced it. France is chief among them, relying on nuclear energy for 71% of its energy needs. Ukraine is the next most dependent on it, for 56% of its power, followed closely by Slovakia, then Belgium, Hungary, Sweden, Slovenia, and the Czech Republic, according to Bloomberg. None of them have a good plan for nuclear waste, other than storing it somewhere in hopes of an eventual solution or thousands of trouble-fee years during which it stays put and doesn't escape into water supplies or the air.

And there's a lot of this stuff. Greenpeace estimates there are roughly 250,000 tons of it in 14 countries across the world. Of that, about 22,000 cube meters is hazardous. The cost of storing it all, according to GE-Hitachi, is more than $100 billion, (discounting China, Russia, and India).

Transmuting the nuclear waste problem

([general-fmv]/Shutterstock)

The process Mourou is investigating is called "transmutation." "Nuclear energy is maybe the best candidate for the future," he told the Nobel audience, "but we are still left with a lot of dangerous junk. The idea is to transmute this nuclear waste into new forms of atoms which don't have the problem of radioactivity. What you have to do is to change the makeup of the nucleus." After his speech he phrase his plans for lasers and waste more plainly: "It's like karate — you deliver a very strong force in a very, very brief moment."

The idea of transmutation's not new. It's been under investigation for 30 years in the U.K., Belgium, Germany, Japan, and the U.S. Some of these efforts are ongoing. Others have been given up. Rodney C. Ewing of Stanford tells Bloomberg, "I can imagine that the physics might work, but the transmutation of high-level nuclear waste requires a number of challenging steps, such as the separation of individual radionuclides, the fabrication of targets on a large scale, and finally, their irradiation and disposal."

Mourou and Tajima hope to be able to shrink the distance a light beam has to travel to transmute atoms by a further 10,000 times. "I think about what it could mean all the time," Mourou says at Ecole Polytechnique, where he teaches. "I don't overlook the difficulties that lie ahead. I dream of the idea, but we will have to wait and see what happens in the years to come."

Neom, Saudi Arabia's $500 billion megacity, reaches its next phase

Construction of the $500 billion dollar tech city-state of the future is moving ahead.

Credit: Neom
Technology & Innovation
  • The futuristic megacity Neom is being built in Saudi Arabia.
  • The city will be fully automated, leading in health, education and quality of life.
  • It will feature an artificial moon, cloud seeding, robotic gladiators and flying taxis.
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Human brains remember certain words more easily than others

A study of the manner in which memory works turns up a surprising thing.

Image Point Fr / Shutterstock
Mind & Brain
  • Researchers have found that some basic words appear to be more memorable than others.
  • Some faces are also easier to commit to memory.
  • Scientists suggest that these words serve as semantic bridges when the brain is searching for a memory.

Cognitive psychologist Weizhen Xie (Zane) of the NIH's National Institute of Neurological Disorders and Stroke (NINDS) works with people who have intractable epilepsy, a form of the disorder that can't be controlled with medications. During research into the brain activity of patients, he and his colleagues discovered something odd about human memory: It appears that certain basic words are consistently more memorable than other basic words.

The research is published in Nature Human Behaviour.

An odd find

Image source: Tsekhmister/Shutterstock

Xie's team was re-analyzing memory tests of 30 epilepsy patients undertaken by Kareem Zaghloul of NINDS.

"Our goal is to find and eliminate the source of these harmful and debilitating seizures," Zaghloul said. "The monitoring period also provides a rare opportunity to record the neural activity that controls other parts of our lives. With the help of these patient volunteers we have been able to uncover some of the blueprints behind our memories."

Specifically, the participants were shown word pairs, such as "hand" and "apple." To better understand how the brain might remember such pairings, after a brief interval, participants were supplied one of the two words and asked to recall the other. Of the 300 words used in the tests, five of them proved to be five times more likely to be recalled: pig, tank, doll, pond, and door.

The scientists were perplexed that these words were so much more memorable than words like "cat," "street," "stair," "couch," and "cloud."

Intrigued, the researchers looked at a second data source from a word test taken by 2,623 healthy individuals via Amazon's Mechanical Turk and found essentially the same thing.

"We saw that some things — in this case, words — may be inherently easier for our brains to recall than others," Zaghloul said. That the Mechanical Turk results were so similar may "provide the strongest evidence to date that what we discovered about how the brain controls memory in this set of patients may also be true for people outside of the study."

Why understanding memory matters

person holding missing piece from human head puzzle

Image source: Orawan Pattarawimonchai/Shutterstock

"Our memories play a fundamental role in who we are and how our brains work," Xie said. "However, one of the biggest challenges of studying memory is that people often remember the same things in different ways, making it difficult for researchers to compare people's performances on memory tests." He added that the search for some kind of unified theory of memory has been going on for over a century.

If a comprehensive understanding of the way memory works can be developed, the researchers say that "we can predict what people should remember in advance and understand how our brains do this, then we might be able to develop better ways to evaluate someone's overall brain health."

Party chat

Image source: joob_in/Shutterstock

Xie's interest in this was piqued during a conversation with Wilma Bainbridge of University of Chicago at a Christmas party a couple of years ago. Bainbridge was, at the time, wrapping up a study of 1,000 volunteers that suggested certain faces are universally more memorable than others.

Bainbridge recalls, "Our exciting finding is that there are some images of people or places that are inherently memorable for all people, even though we have each seen different things in our lives. And if image memorability is so powerful, this means we can know in advance what people are likely to remember or forget."

spinning 3D model of a brain

Temporal lobes

Image source: Anatomography/Wikimedia

At first, the scientists suspected that the memorable words and faces were simply recalled more frequently and were thus easier to recall. They envisioned them as being akin to "highly trafficked spots connected to smaller spots representing the less memorable words." They developed a modeling program based on word frequencies found in books, new articles, and Wikipedia pages. Unfortunately, the model was unable to predict or duplicate the results they saw in their clinical experiments.

Eventually, the researchers came to suspect that the memorability of certain words was linked to the frequency with which the brain used them as semantic links between other memories, making them often-visited hubs in individuals's memory networks, and therefore places the brain jumped to early and often when retrieving memories. This idea was supported by observed activity in participants' anterior temporal lobe, a language center.

In epilepsy patients, these words were so frequently recalled that subjects often shouted them out even when they were incorrect responses to word-pair inquiries.

Seek, find

Modern search engines no longer simply look for raw words when resolving an inquiry: They also look for semantic — contextual and meaning — connections so that the results they present may better anticipate what it is you're looking for. Xie suggests something similar may be happening in the brain: "You know when you type words into a search engine, and it shows you a list of highly relevant guesses? It feels like the search engine is reading your mind. Well, our results suggest that the brains of the subjects in this study did something similar when they tried to recall a paired word, and we think that this may happen when we remember many of our past experiences."

He also notes that it may one day be possible to leverage individuals' apparently wired-in knowledge of their language as a fixed point against which to assess the health of their memory and brain.

Does conscious AI deserve rights?

If machines develop consciousness, or if we manage to give it to them, the human-robot dynamic will forever be different.

Videos
  • Does AI—and, more specifically, conscious AI—deserve moral rights? In this thought exploration, evolutionary biologist Richard Dawkins, ethics and tech professor Joanna Bryson, philosopher and cognitive scientist Susan Schneider, physicist Max Tegmark, philosopher Peter Singer, and bioethicist Glenn Cohen all weigh in on the question of AI rights.
  • Given the grave tragedy of slavery throughout human history, philosophers and technologists must answer this question ahead of technological development to avoid humanity creating a slave class of conscious beings.
  • One potential safeguard against that? Regulation. Once we define the context in which AI requires rights, the simplest solution may be to not build that thing.

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