Jul 25, 2019

Axios Science

By Alison Snyder
Alison Snyder

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1 big thing: Einstein's disappointing success

Illustration: Rebecca Zisser/Axios

Time and time again, Einstein's theory of general relativity passes cosmic tests near and far. It's a testament to the physicist's ingenuity and scientific and technological progress.

But physicists also want to see general relativity fail a test.

  • It's through such failures that they hope to discover physics that explains what Einstein's and Newton's equations cannot — the creation of the universe or what happens inside a black hole.

Driving the news: UCLA's Andrea Ghez and her colleagues report today in Science that light from a star (dubbed S0-2) passing close to the supermassive black hole at the center of the Milky Way is affected as Einstein's theory predicts.

  • The new work complements that of the GRAVITY collaboration at the European Southern Observatory.
  • Both teams relied on detailed measurements of the star's 16-year orbit — Ghez helped to take the first measurement in 1995 — to detect the effects of gravity.
  • Test time came in 2018 when the star passed within 120 astronomical units of the black hole — about 3 times the distance between our Sun and Pluto.

Details: Using the historical data for the star's orbit as a reference, the teams took measurements of the light emitted from the star as it moved by the black hole. They observed it was redder because, as predicted, it lost energy due to the effects of gravity from the black hole.

  • In the new study, the researchers report general relativity is 43,000 times more likely than Newtonian physics to describe the observations.

Researchers applaud the new study — the precision of the measurements, the patience of the endeavor, and the avenues of investigation it opens. But Einstein's continued success is a challenge for the field.

  • "One of the problems we have is that Einstein’s theory just keeps passing the test over and over again. And we know that it can’t be the complete story," says Geraint Lewis, a professor of astrophysics at the University of Sydney.
  • "It is exciting and disappointing at the same time."
  • Einstein's and Newton's equations are correct — under certain conditions.
  • The search is for an all-encompassing construct to describe the universe, which the physics of Newton and Einstein would be part of, says Zoltan Haiman, a theoretical physicist at Columbia University.

What's next: Knowing details of S0-2's path, researchers want to track the star to see if its orbit will rotate like general relativity predicts.

  • They also want to use results from recent experiments to home in on even powerful tests where different aspects of Einstein's theory might not hold.
  • "It has been tested in so many different ways that any deviation would be instantaneously surprising," says Tuan Do, a research scientist at UCLA who helped to lead the study with Ghez.
2. The tricky business of improving brains

Illustration: Sarah Grillo/Axios

Connecting brains directly to machines has helped paralyzed people begin to speak and amputees feed themselves again — early steps toward the miraculous cures that have been the main focus of the neurotechnology field, Axios' Kaveh Waddell writes.

But a smaller group of researchers and startups — plus the Pentagon — are working toward an even longer-term goal fraught with scientific and moral hurdles. They plan to improve on healthy humans, in a bid to pick up where evolution left off.

How it works: These technologies communicate with the brain — from outside the skull or by sticking electrodes straight into it — in order to read neural data, and often also to write information back in.

  • Theoretically, people could acquire senses they're not born with or be jacked into a computer or a faraway drone, controlling it like an extension of their body.

But a likely earlier outcome is connecting brains and machines to help people learn the way they always have — just a little faster.

  • Researchers at Carnegie Mellon and the University of Pittsburgh are reading data from volunteers' brains as they learn to control a computer cursor with their minds. Understanding which tasks are easier or harder to pick up could help eventually develop counterintuitive ways to learn faster — customized for each person's mind.
  • Scientists at the University of Maryland are testing an earbud that stimulates the vagus, an important nerve connected to the brain stem, to temporarily boost a person's learning capacity. In early tests, it has speeded up second-language learning, says Polly O'Rourke, the researcher leading the study.

What's next: One early concern is whether these inventions would be out of reach for some, granting wealthy people superpowers while leaving others with nothing more than their natural cognitive abilities.

  • Another more haunting prospect is that analyzing a person's brain activity could reveal information about their past experiences that they may not want to divulge, says Byron Yu, a Carnegie Mellon professor.

Go deeper.

3. TESS goes on
Expand chart
Model: NASA; Graphic: Harry Stevens/Axios

Last week, NASA extended the life of the Transiting Exoplanet Survey Satellite for 2 more years, through at least 2022, Axios' Miriam Kramer reports.

  • Scientists have found more than 4,000 confirmed exoplanets — 21 of those thanks to TESS.
  • While researchers don’t yet have the technology to a figure out whether a world is Earth-like, the planets TESS finds could be good candidates for follow-up observations from future spacecraft that can answer that question.

Details: TESS is just at the end of the first year of its primary mission. In that time, the telescope discovered a variety of planets, including one that’s only about 80% the size of Earth.

  • For the telescope's next act, it is expected to take a look at some areas already seen and observe the ecliptic, the part of the sky covered by the Sun’s path throughout the year, TESS scientist Sara Seager tells Axios.

Go deeper: Explore the interactive TESS graphic

4. Worthy of your time

Illustration: Aïda Amer/Axios

Special report: Factory Moon (Axios)

Cosmic Crisp: A new apple launches (Brooke Jarvis, California Sunday Magazine)

The opioid epidemic you haven't heard about (Laura Salm-Reifferscheidt, Mosaic)

The brain's waste disposal problems (Eileen Drage O'Reilly, Axios)

The quietly changing consensus on neutering dogs (Sarah Zhang, The Atlantic)

5. Something wondrous

The team's experimental setup. Photo: Sebastian Leuzinger/Auckland University of Technology

A "living stump" of New Zealand's iconic kauri tree seems to share water with a neighbor, hinting that trees could be more deeply connected than previously understood.

The big picture: If trees are found to act more like a resource-sharing superorganism, the "whole view on the functioning of the tree and forest would have to change," says Sebastian Leuzinger, an ecologist at Auckland University of Technology in New Zealand and author of new research describing the stump.

What's new: Vast networks of microbes are known to move carbon and other nutrients between trees in what is known as the "wood wide web." The study — with an n of 1 — suggests water could be moved as well but by the trees' roots themselves.

  • The researchers measured the flow of water in a kauri stump with living tissue on one side that indicated it was somehow feeding itself despite not having any leaves.
  • During the day, when trees transpire — moving water to their leaves where it evaporates — water didn't move much into the stump.
  • But when the host tree stopped transpiring at night, water circulated quickly in the stump.
  • They suspect the roots of the tree are grafted to those of the stump — which is known to happen in other species.

What's next: Leuzinger wants to study whether water is regularly exchanged in intact trees as well.

  • If it is, he says it could change models of how forests respond to drought and possibly explain how pathogens — like the kauri dieback disease that is wiping out the trees in New Zealand — move through forests.

P.S. There are beautiful pictures of kauri trees on the internet. I chose this one because sometimes science involves duct tape and bungee cords.

Spend some time in the woods:

Alison Snyder