Readers discuss big bacteria, gravitational radar and more

Biggest bacteria?

A newfound species of bacteria, Thiomargarita magnifica, averages 1 centimeter long and can be seen by the naked eye, making it the largest bacteria yet discovered, Erin Garcia de Jesús reported in “Newfound bacteria make a big splash” (SN: 7/16/22 & 7/30/22, p. 17).

Reader J.C. Smith pointed out that another article in the magazine seems to contradict the findings in this story. In “Live wires,” Nikk Ogasa reported that cable bacteria, which channel electricity, can grow up to 5 centimeters long (SN: 7/16/22 & 7/30/22, p. 24).

This is no contradiction, Garcia de Jesús says. T. magnifica is a single-celled species of bacteria, which means all of the cellular functions necessary for the organism’s survival happen within its one cell. Cable bacteria, on the other hand, are multicellular, with different cells performing different functions. “T. magnifica is the largest single-celled bacterium ever found,” Garcia de Jesús says.

Given that bacteria are typically defined as single-celled organisms, reader Barry Maletzky wondered how multicellular cable bacteria can be considered part of the group.

Most bacteria are single-celled, Ogasa says, but several multicellular species do exist. “For instance, some cyanobacteria, sometimes called blue-green algae, are also multicellular. That allows the organisms to split the jobs of photosynthesis and nitrogen absorption between cells.”

Mapping out space

Massive objects that warp spacetime can redirect gravitational waves. Researchers might someday leverage those waves as a kind of gravity “radar” to peer inside stars and find globs of dark matter, Asa Stahl reported in “Gravitational wave ‘radar’ could map the universe” (SN: 7/16/22 & 7/30/22, p. 12).

Reader Neil Kaminar wondered if changes in the frequency of light coming from massive objects could be used to detect the distortion of spacetime.

In theory, yes, says Glenn Starkman, a physicist at Case Western Reserve University in Cleveland. When light travels through spacetime toward or away from a massive object, gravity changes the frequency of the light, he says. Scientists have witnessed one form of this process, called gravitational redshift, in action on Earth.

But this effect would probably not be very useful when it comes to gravitational radar, Starkman says. After light moves toward a massive object, changing its frequency, it would then move away from the object. That process would shift the light’s frequency toward what it was before the encounter, mostly canceling out the effect, Starkman says.

Science and society

In “We won’t shy away from covering politicized science,” editor in chief Nancy Shute reflected on Science News’ history of reporting on the science of politically contentious issues and asserted our commitment to continue that coverage (SN: 7/16/22 & 7/30/22, p. 2).

Brigitte Dempsey was glad to read Shute’s editor’s note in the wake of the U.S. Supreme Court striking down Roe v. Wade, the landmark decision that had protected a person’s right to an abortion. Since then, debates around abortion and pregnancy biology have become more heated, and accurate science is often missing from the discussions (SN: 7/16/22 & 7/30/22, p. 6). “Bravo for meeting the issue square on,” Dempsey wrote. “Our only hope to bring reason to bear … is to let science speak.”