After billions of years of monotony, the universe is waking up | David Deutsch

0
Theoretical physicist David Deutsch delivers a mind-bending meditation on the “great monotony” — the idea that nothing novel has appeared in the universe for billions of years — and shows how humanity’s capacity to create explanatory knowledge could be the thing that bucks this trend. “Humans are not playthings of cosmic forces,” he says. “We are users of cosmic forces.”

How we can eliminate child sexual abuse material from the internet | Julie Cordua

0
Social entrepreneur Julie Cordua works on a problem that isn’t easy to talk about: the sexual abuse of children in images and videos on the internet. At Thorn, she’s building technology to connect the dots between the tech industry, law enforcement and government — so we can swiftly end the viral distribution of abuse material and rescue children faster. Learn more about how this scalable solution could help dismantle the communities normalizing child sexual abuse around the world today. (This ambitious plan is part of the Audacious Project, TED’s initiative to inspire and fund global change.)

An app that helps incarcerated people stay connected to their families | Marcus Bullock

0
Over his eight-year prison sentence, Marcus Bullock was sustained by his mother’s love — and by the daily letters and photos she sent of life on the outside. Years later, as an entrepreneur, Bullock asked himself: How can I make it easier for all families to stay connected during incarceration? Enter FlikShop: an app he developed that lets families send quick postcards to loved ones in prison and help keep open a critical line of support.

How family separation at the US-Mexico border affects children's mental health | Luis H. Zayas

0
How does psychological trauma affect children’s developing brains? In this powerful talk, social worker Luis H. Zayas discusses his work with refugees and asylum-seeking families at the US-Mexico border. What emerges is a stunning analysis of the long-term impact of the US’s controversial detention and child separation policies — and practical steps for how the country can do better.

Physicists have found quasiparticles that mimic hypothetical dark matter axions

0

An elusive hypothetical particle comes
in imitation form.

Lurking within a solid crystal is a
phenomenon that is mathematically similar to proposed subatomic particles
called axions
, physicist Johannes
Gooth and colleagues report online October 7 in Nature.

If axions exist as fundamental
particles, they could constitute a hidden form of matter in the cosmos, dark
matter. Scientists know dark matter exists thanks to its gravitational pull,
but they have yet to identify what it is. Axions are one possibility, but no one has found the particles yet (SN: 4/9/18).

Enter the imitators. The axions analogs
within the crystal are a type of quasiparticle, a disturbance in a material that
can mimic fundamental particles like axions. Quasiparticles result from the
coordinated jostling of electrons within a solid material. It’s a bit like how birds
in a flock seem to take on new forms by syncing up their movements.

Axions were first proposed in the
context of quantum chromodynamics — the theory that explains the behaviors of quarks,
tiny particles that are contained, for example, inside protons. Axions and
their new doppelgängers “are mathematically similar but physically totally
unrelated,” says theoretical physicist Helen Quinn of SLAC National Accelerator
Laboratory in Menlo Park, Calif., one of the scientists who formulated the
theory behind axions. That means scientists are no closer to solving their dark
matter woes.

Still, the new study reveals for the
first time that the phenomenon has a life beyond mere equations, in
quasiparticle form. “It’s actually amazing,” says Gooth, of the Max Planck Institute
for Chemical Physics of Solids in Dresden, Germany. The idea of axions is “a
very mathematical concept, in a sense, but it still exists in reality.”

In the new study, the researchers
started with a material that hosts a type of quasiparticle known as a Weyl fermion,
which behaves as if massless (SN: 7/16/15).
When the material is cooled, Weyl fermions become locked into place, forming a
crystal. That results in the density of electrons varying in a regular pattern
across the material, like a stationary wave of electric charge, with peaks in
the wave corresponding to more electrons and dips corresponding to fewer
electrons.

Applying parallel electric and magnetic
fields to the crystal caused the wave to slosh back and forth. That sloshing is
the mathematical equivalent of an axion, the researchers say.

To confirm that the sloshing was
occurring, the team measured the electric current through the crystal. That
current grew quickly as the researchers ramped up the electric field’s strength,
in a way that is a fingerprint of axion quasiparticles.

If the scientists changed the direction
of the magnetic field so that it no longer aligned with the electric field, the
enhanced growth of the electric current was lost, indicating that the axion
quasiparticles went away. “This material behaves exactly as you would expect,”
Gooth says.