Readers weigh in on brain technology, black holes and more

Mind readers

Scientists are grappling with the ethical implications of new technology that aims to listen to and perhaps change brain activity, Laura Sanders reported in “Inside your head” (SN: 2/13/21, p. 24).

“Interesting and provocative read,” reader Andrew Nelson wrote. “Once the intricacies of our thoughts become recordable (or worse, reproducible), they will be misused.” Linking neural activity with specific actions could establish causal relationships that could be used to control mental processes without a person’s knowledge, Nelson wrote. “That’s the scary part!”

To shape Sanders’ story, Science News surveyed readers like Nelson about their opinions on brain science advances, editor in chief Nancy Shute explained in her editor’s note for the issue (SN: 2/13/21, p. 2). Reader Danny Otero applauded the effort to involve the public in conversations about the thorny ethical issues surrounding neurotechnology. But “great science journalism … rests on finding the truth from experts,” he wrote. “Why not then involve professional ethicists in this discussion?”

Science News consults experts in our reporting, and Sanders spoke with ethicists for the story. “We would love to connect ethicists with readers and scientists for in-depth conversations about these issues,” Shute says. “Finding out about readers’ concerns so we could address them in our reporting was just the first step. We hope to be able to help encourage more connections and conversations in the future,” she says.

Packing on the solar masses

The oldest known black hole lies at the center of a galaxy 13 billion light-years from Earth and has a mass equivalent to 1.6 billion suns, Maria Temming reported in “Oldest known black hole mystifies scientists” (SN: 2/13/21, p. 4).

If the black hole, dubbed J0313-1806, was that massive 13 billion years ago, reader Arthur Silverthorn wondered how much it weighs now.

Scientists don’t know how massive the black hole is now. “Black holes … stop growing at some point after consuming all the available gas,” says astronomer Feige Wang of the University of Arizona in Tucson. “We do not know when that would happen,” Wang says. But the biggest known black hole is about 66 billion solar masses. The mass of J0313-1806 would likely not be more than that, he says.

Shocking science

Volta’s electric eels can hunt in groups of more than 100, with smaller groups of about 10 eels unleashing coordinated electric attacks on prey, Jonathan Lambert reported in “Electric eels shock with swarm hunting tactics” (SN: 2/13/21, p. 4).

Reader Jerry Kerrisk wondered if the voltage generated by a group of eels is any different from that of a single eel.

One Volta’s electric eel can generate an 860-volt jolt, so in theory, a group of 10 eels could generate 8,600 volts, says evolutionary biologist Carlos David de Santana of the Smithsonian National Museum of Natural History in Washington, D.C. But his team has yet to measure the shock output of a group.

The total discharge from 10 joint eel strikes would probably cover a broader area and last longer than a single strike, and not exceed 860 volts, de Santana speculates. He hopes to gather more field observations in the fall.


Zoologist Lee-Sim Lim of Universiti Sains Malaysia in Penang worked with Priscillia Miard, also of the university, to discover the ultrasound calls of colugos described in “A night with colugos” (SN: 11/21/20, p. 22).


Solar storm preparedness” (SN: 2/27/21, p. 16) incorrectly stated that coronal mass ejections produce shock waves that accelerate electrons to extremely fast speeds. The shock waves accelerate protons.