Readers Respond to the September 2025 Issue

SETI THE STRAIGHT RECORD

In “We’re Probably Not Alone,” Sarah Scoles describes how Italian astronomer Giovanni Schiaparelli’s 1877 observation of apparent “canals” or “rilles” on Mars led to a widespread belief that the planet was home to “canal-digging civilizations” thanks to a translation error. Scoles notes that this idea “began to lose its luster in 1909, when the French astronomer Eugène Antoniadi” discovered that the lines seen by Schiaparelli were an optical illusion.

The same conclusion as Antoniadi’s had been made three decades earlier. In the February 2024 issue of Journal for the History of AstronomyI published an article on the history of astronomical observations made on the island of Madeira. I emphasize that in 1877, the same year in which Schiaparelli affirmed this, the amateur astronomer and professional artist Nathaniel Everett Green took advantage of “the transparency of the air of Madeira” to observe Mars, as he wrote in the Memoirs of the Royal Astronomical Society in 1879. He noted that “it would be difficult to exaggerate the cartographic aspect of the planet”, which allowed him to conclude that “the remarkable dark channels…of Professor Schiaparelli…were certainly invisible in Madeira”.

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Green invoked an optical illusion to explain Schiaparelli’s error. This account followed Green’s previous report on his observations in the prestigious Monthly Notices of the Royal Astronomical Society in 1877.

PEDRO AUGUSTO PORTO, PORTUGAL

Although Scoles’ story of the search for extraterrestrial life is interesting, I believe she missed the most important reason to believe that such life exists. This is a difficult question for us simple humans to understand: infinity. If the universe is infinite, then there must be many other planets on which life lives. The problem is that the laws of physics say that we are all limited by the speed limit of the speed of light. This means that life exists on many worlds, in many galaxies, but we and it can never find each other. Let’s keep looking anyway; the quest for knowledge is inextinguishable!

WES MOFFETT BY EMAIL

ANATOMICAL CONNECTIONS

Scientists themselves might benefit from reading Scientific American! In the July/August 2025 issue, two Advances articles report findings that may be related to those noted in previous issues.

“Wandering Spirit”, by Nora Bradford [Advances; July/August 2025]is about scientists studying how participants learn hidden patterns in tasks better when they let their minds wander. Researchers might want to check out “Speed ​​Limit,” by Rachel Nuwer [Advances; March 2025]and note the results described that the focused mind processes at about 10 bits per second, while sensory systems do so at about a billion bits per second. This confirms Queen’s University psychology researcher Jonathan Smallwood’s supposition in Bradford’s paper that it is the “particular state” in which mind wandering occurs, rather than mind wandering itself, that causes people to learn such patterns: the lack of concentration allows the body, working with these billions of bits per second, to understand the problem. I’ve experienced this myself for decades: when faced with a repetitive physical task, I immediately step away from thinking and let my body work out a process.

“Screaming Skin,” by Allison Parshall [Advances; July/August 2025]describes how Sun-Min Yu of the University of Massachusetts Amherst and his team discovered that epithelial cells emit a signal when damaged that “can call on other cells to help rebuild damaged places.” Yu’s team could consult Martin Picard’s June 2025 article “The social life of mitochondria”. Picard shows how mitochondria, present in every cell in the body, communicate with each other, especially when they need help. They do this between cells and by influencing multiple subsystems within each cell.

Mr. FOSQUE HILLSBOROUGH, North Carolina

SLIME THAT HEALS?

In “Slime Attack” [Advances; July/August 2025]Elizabeth Anne Brown describes research into velvet worm slime, which can harden in seconds.

As someone who takes various cardiovascular medications that cause blood thinning and heavy bleeding with the slightest scratch or scrape, I wonder if this slime or similar substances might have any application in stopping bleeding from a wound. (Besides people like me, this would be helpful for hemophiliacs.) The almost instant hardening could quickly form a barrier over the wound. And as noted in the article, the substance reverts to a liquid state when soaked in water, so it could easily be washed off later.

GARY McKOWN WEST CHESTER, PA.

ICED EVALUATION

In “Freezing the Arctic” [June 2025]Alec Luhn reports on researchers trying to reconstruct sea ice above the Arctic Circle to reflect solar radiation and thus slow climate change. I hope you will continue by discussing other ways of restoring the Arctic ice sheet.

I’m particularly interested in snow production because it seems to have several advantages over ice. For one thing, in addition to being more reflective than ice, snow is far superior insulation, as Luhn notes. So a layer of snow would keep the ice sheet colder than a layer of ice of the same mass – and for longer. Additionally, snow production would allow for much larger coverage areas per pump station, thereby reducing material costs.

CHRISTMAS KURTZ BY EMAIL

CLARIFICATION

“Getting Closer to a Cure,” by Tara Haelle [Innovations In Type 1 Diabetes; November 2025]noted the drug in development Zimislecel from Vertex Pharmaceuticals. Breakthrough T1D did not fund trials of this drug. To learn more about its mechanism of action, intended recipients and trial results, visit www.scientificamerican.com/article/a-cure-for-type-1-diabetes-may-be-closer-than-you-think.

ERRATA

“Bass Backlash,” by Martin J. Kernan [Advances; November 2025]should have clarified that the historic proliferation of smallmouth bass in Little Moose Lake caused the native trout to reach only nine inches long then rather than today.

“The Meteorite Flight”, by Dan Vergano [November 2025]should have said that, according to Nicholas Gessler, the Eli Ali object is offered for sale in pieces at 200 dollars per kilo.

In “Organized Chaos,” by Aimee Lucido [Science Crossword; November 2025]the question for 16-Across should have specified a drum kit component.