Hi Reader, the CIA’s most famous code was finally cracked. By accident. For 35 years, Kryptos, the copper sculpture by Jim Sanborn standing in the CIA’s courtyard, has taunted codebreakers worldwide. Three of its four encrypted messages were solved long ago; the last, K4, resisted even supercomputers. Last week, the mystery was solved not by cryptographers but by two “amateurs”. Novelist Jarett Kobek stumbled on the plaintext in the Smithsonian archives, hidden among Sanborn’s old papers. A wonderful reminder that big breakthroughs often come looking sideways at problems everyone else stares straight at, as we’ll see in some of this week’s stories.

Coming up this week:
👁️ A microchip that helped blind patients read again
🧊 Ice that freezes at room temperature and what it means
🧠 Why men’s brains age faster than women’s (and what that means for Alzheimer’s research)
​+more

Question Time​
Australia is Wider than the Moon
True or False?

The answer is true, surprisingly! The land down under is 500km wider than the moon.

That’s just one of hundreds of mind-bending questions in Elements of Truth, our new Veritasium board game launching this November on Kickstarter. Created with scientists and game designers, it’s a trivia experience built on the themes of curiosity, confidence, and discovery.

Pre-register now to get exclusive early-bird rewards and access to the limited Kickstarter edition. Once it’s gone, it’s gone.

If you think you can tell fact from fiction then be the first in line for launch day!

BIOENGINEERING

Tiny Eye Implant Lets Blind Patients Read Again

Starting around 2020, 38 patients enrolled in a clinical trial at 17 hospitals across five European countries. Each was hoping to be part of a breakthrough that would reverse their blindness. All had lost their central vision to geographic atrophy, an advanced form of dry age-related macular degeneration that destroys the retina's center and leaves patients legally blind. This degeneration affects 5 million people worldwide and there is currently no treatment. Until now.

This week, results published in the New England Journal of Medicine demonstrate the trial's success. In a less-than 2-hour surgery, surgeons implanted a device the size of a grain of rice beneath each patient's retina, a 2 mm × 2 mm microchip, half the thickness of a human hair. Then came months of rehabilitation, learning to use augmented-reality glasses that worked with the implant. Slowly, letters appeared. Then numbers. Then short words. After one year, 84% could read again.

The device is called the PRIMA System, and Dr. Mahi Muqit of Moorfields Eye Hospital calls it "a new era" in artificial vision. "Blind patients are actually able to have meaningful central vision restoration, which has never been done before."

This video shows how it works. The microchip sits beneath the damaged macula, the retina's central region responsible for sharp vision. Patients wear special glasses equipped with a camera and AI processor. The glasses capture the scene in front of them and project it as infrared light patterns onto the chip. The chip converts those patterns into electrical signals, which the optic nerve carries to the brain. The brain interprets them as vision.

This isn't full sight restoration (patients don't see the way they did before the disease) but it's reading-level central vision, something doctors thought the patients had permanently lost. Sheila Irvine, a 70-year-old who received the implant at Moorfields Eye Hospital in London, had described living with her blindness as having dark circles blocking her central view. An enthusiastic reader before losing her sight, she can now tackle crossword puzzles and make out the text on medicine bottles.

TL;DR: A microscopic retinal chip paired with processing glasses restored reading-level vision in 84% of blind AMD patients - a landmark for artificial vision and a glimpse of how technology may one day repair the eye.

PHYSICS

Scientists Freeze Water at Room Temperature Under Pressure

Inside a chamber at the European XFEL - the world's largest X-ray laser - Geun Woo Lee watched a droplet of water freeze at room temperature. Lee, a scientist at the Korea Research Institute of Standards and Science, has spent years probing one of water's deepest puzzles: how such a simple molecule can form at least 20 different solid structures. “Water is one of the most mysterious materials in the universe," he says.

This week, in a paper published in Nature Materials, Lee and his international team report the discovery of ice XXI. To make it, they trapped water between two diamond tips and squeezed it to 2 gigapascals (20,000 times atmospheric pressure) in ten milliseconds, then released the pressure gradually. They repeated this more than 1,000 times. What emerged wasn’t the familiar hexagonal ice of snowflakes, but a tetragonal lattice of 152 water molecules - a geometry never seen before.

"Rapid compression allows water to remain liquid up to higher pressures, where it should have already crystallized to ice VI," Lee explains. That window, what Lee calls a "hidden path", is where ice XXI appears, existing for only tens of microseconds before transforming into ice VI.

The implications go far beyond laboratory curiosity. The pressures that create ice XXI are comparable to those thought to exist deep inside icy moons like Ganymede and Titan, suggesting that similar high-pressure ice layers could influence heat flow and ocean stability there. Knowing that water can form new structures even at moderate temperatures could reshape models of planetary interiors, changing how we think about heat transport, magnetic fields, and the habitability of ocean worlds.

TL;DR: By compressing water between diamonds and tracking it with X-ray lasers, scientists made ice XXI, a brand-new solid phase that forms at room temperature, revealing hidden routes in water’s strange phase diagram.

NEUROSCIENCE

Do Men’s and Women’s Brains Age Differently?

Women make up nearly two-thirds of all Alzheimer’s cases worldwide, a gap that’s puzzled scientists for some time. One leading hypothesis was that women’s brains age faster, particularly around menopause, making them more vulnerable to Alzheimer’s disease.

A new study published in PNAS challenges that idea. Researchers at the University of Oslo analyzed 12,638 MRI scans from 4,726 healthy adults, aged 17 to 95, tracking how individual brains changed over time. Unlike earlier snapshot-style studies, which used one MRI per person and compared different individuals at different ages, this one followed the same people across years, allowing the researchers to watch their brains age in real time.

The results flipped expectations. Men’s brains shrank faster than women’s, showing steeper annual declines in total brain volume and cortical thickness across multiple regions, from visual and parahippocampal areas to deep structures like the caudate and putamen. Women showed fewer areas of decline but more ventricular expansion.

Those patterns, the authors say, are “too small to explain” the higher prevalence of Alzheimer's among women. The culprit, then, likely lies elsewhere - in genetics, hormones, longevity, or diagnostic bias - not in healthy aging itself. “We found modest but systematic sex differences in age-related brain decline…These findings suggest that the higher prevalence of AD diagnoses in women likely stems from factors beyond differential rates of age-related brain atrophy,” the authors write.

The findings hint at wider implications. If male brains age faster structurally, their window for intervention may be narrower—perhaps shaped by cardiovascular risk, hormonal factors, or lifestyle differences. None of these explanations have been confirmed, but all deserve attention. What’s clear is that brain aging isn’t sex-neutral, and understanding those patterns could help tailor future strategies for prevention and early cognitive care.

Still, the findings sharpen our understanding of how sex influences brain health. Brain aging, it turns out, isn’t sex-neutral but its consequences may be more complex than simple shrinkage.

TL;DR: A massive study finds that men’s brains shrink faster than women’s, overturning the assumption that women’s faster brain aging explains their higher Alzheimer’s risk and pushing researchers to look beyond anatomy for answers.

In Other News

Are we seeing dark matter collide in the Milky Way? Detailed gamma-ray maps of the Milky Way’s centre show a glow consistent with dark-matter particle annihilations, strengthening the case that we may be seeing dark matter at work.

Chinese-American physicist and Nobel laureate dies at 103. Chen Ning Yang, a Nobel-winning physicist whose insights into parity violation and gauge theory transformed modern physics, has died at 103, leaving a legacy at the heart of how we understand matter and forces.

Shark-bite resistant wetsuits. Researchers have developed and field-tested bite-resistant wetsuits that integrate Kevlar and nanofibres, showing large shark bites cause far less severe damage than on standard neoprene.

The optimal way to optimize. Nearly 80 years after George Dantzig invented the simplex method, mathematicians have proved it’s already optimal—showing the classic algorithm that powers global logistics can’t be fundamentally improved without changing its model.

BPA found in “BPA-Free” pacifiers from major brands. Tests on 21 “BPA-free” baby pacifiers found BPA in four, including one brand at nearly double the EU limit, exposing a loophole in safety regulation for infant products.

The hidden counter-jet of a famous black hole. The James Webb Space Telescope has captured the most detailed infrared image yet of the giant black hole in galaxy M87, revealing not just its main jet of energy but a second, hidden jet shooting out the other side.

Mathematicians have found a hidden “reset button” for undoing rotation. Mathematicians proved that almost any 3-D rotation sequence can be perfectly undone by scaling it and repeating it twice - a universal “reset” trick with potential uses in robotics, quantum computing, and control systems.

This Week in History

October 20, 1984. Paul Dirac, one of the most brilliant yet reserved minds in physics, died. He fused quantum mechanics with relativity, predicted antimatter, explained particle spin, and built the mathematical framework that still underpins particle physics today. (This video series on Dirac’s quantum electrodynamics is superb.) Feynman called him a hero; Einstein confessed, “I have a lot of trouble with Dirac. This balancing on the dizzying path between genius and madness is awful.” Dirac shared the 1933 Nobel Prize with Erwin Schrödinger, but his influence reaches far beyond prizes: every physicist probing the quantum world still walks in his mathematical footsteps.

October 18, 1955. At UC Berkeley, scientists smashed atoms with 6.2 billion electron volts and found antimatter. They detected the antiproton - the proton’s negatively charged twin - confirming that matter and antimatter mirror each other. Just 60 particles were spotted, but it was enough to prove one of Paul Dirac’s boldest predictions and earn Emilio Segrè and Owen Chamberlain the 1959 Nobel Prize.

October 18, 1962. James Watson, Francis Crick, and Maurice Wilkins received the Nobel Prize for revealing the double-helix structure of DNA - the elegant spiral that encodes life itself. Nearly a century after DNA was first isolated, their model showed how genetic information copies and transmits from cell to cell, transforming biology into a molecular science.

This Week’s Puzzle

🧩

Clueless Monty Hall

You’re a contestant on Monty Hall’s famous game show.

Three doors stand before you: behind one is a brand-new car, and behind the other two are goats.

You pick one door. But it stays closed. Whatever is behind the door you finally end up choosing will be your prize.

Monty, who knows where the car is, then opens one of the other two doors, revealing a goat. He gives you a choice: stick with your original door, or switch to the other unopened one.

If you’ve heard this before, you know the counterintuitive result: you should switch. In the classic version, switching gives you a 2/3 chance of winning instead of 1/3.

But this time, something strange happens.

Just as Monty reaches for a handle, he hesitates. “Oh dear,” he says, “I’ve completely forgotten which door has the car behind it!”

He shrugs, picks one of the two remaining doors at random, and opens it. Luckily for him, it’s a goat.

Now everything looks exactly like the usual Monty Hall setup:

• One door you picked (still closed)
• One unopened door
• One goat revealed

Should you still switch?

Until next time,

The Ve Team 👋

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Solution

No. In this version, it doesn’t matter whether you switch or stay. Your odds are now 50–50.

In the classic Monty Hall problem, Monty’s decision carries information. He knows where the car is, so when he deliberately opens a goat door, that action depends on the car’s position. His choice effectively “filters” the possibilities, leaving your first door with its original 1/3 chance and the other unopened door with the remaining 2/3.

In this clueless version, Monty’s choice is random. He might open a goat or accidentally reveal the car. If he happens to reveal a goat, that outcome doesn’t tell you anything new. It only tells you that Monty got lucky.

Since his choice no longer depends on where the car is, his action adds no new information. Once the lucky goat door opens, the two remaining doors are perfectly symmetrical - each has a 50% chance of hiding the car.

Bonus thought: Imagine there are 1,000 doors instead of three. In the classic version, Monty opens 998 goat doors, deliberately avoiding the car. Switching then gives you a staggering 999/1000 chance of winning. But if Monty is clueless and opens 998 goat doors at random, the symmetry returns and the remaining two doors are again 50–50.