Category: Science

Far, far away (in stellar terms).

Deep space is beyond anything we have ever known.

Like many other people, I am fascinated by the dark, clear, night sky. It appears to go on forever.

But this ‘foreverness’ is just our galaxy.

As is said in the following article: “…. if Earth were the size of a pea, the distance to Proxima Centauri would roughly equal the distance between New York and Sydney, Australia.”

The article shows how distant we are, how small we are, how irrelevant we are, in the vastness of the universe.

This article is republished courtesy of The Conversation.

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Could aliens ever visit Earth? An aerospace scientist unpacks the challenges of interstellar spaceflight

The universe is vast and teeming with stars – but if intelligent life exists, it may not be able to visit Earth. NASA, ESA, CSA, STScI, Rohan Naidu (MIT); Image Processing: Joseph DePasquale (STScI), CC BY

Kai James, Georgia Institute of Technology

On May 22, 2026, the Pentagon released a second batch of previously classified photos and videos showing what appear to be unexplained flying objects. These file dumps were the culmination of a process that was set in motion back in July 2023, when a group of government whistleblowers testified before Congress that the U.S. government was secretly in possession of extraterrestrial spacecraft and suspected alien body parts.

That congressional hearing marked the beginning of a cultural shift in which UFO reports are increasingly treated as a matter for serious discussion, both within the government and the scientific community.

A grainy photo of a dark, blurry object in the sky.
The Pentagon released over 200 previously classified UFO files in May 2026. Department of Defense

But is this newfound legitimacy deserved? As an aerospace scientist who studies aircraft and spacecraft design, I approach this question using math, physics and the principles of engineering. To assess the plausibility of alien visitors, it’s necessary to understand the obstacles that an extraterrestrial vessel would need to overcome to reach Earth.

The tyranny of distance

There is no evidence of intelligent alien life in our solar system. So any extraterrestrial visitors would likely have to come from another star system within our Milky Way galaxy.

Proxima Centauri, the star closest to our Sun, is located 4.25 light-years (about 25 trillion miles or 40 trillion kilometers) away.

For perspective, if Earth were the size of a pea, the distance to Proxima Centauri would roughly equal the distance between New York and Sydney, Australia.

Even the stars closest to Earth are incredibly far away.

Since only a fraction of stars are thought to host intelligent life, the nearest alien civilization – if one exists – is surely much farther away than Proxima.

A need for speed

Given the scale of interstellar distances, it’s inevitable that any alien voyage to Earth would span many years and possibly several centuries. But as the time spent in transit increases, so does the risk of catastrophic accidents or system malfunctions that could jeopardize the mission. So it’s important to avoid an overly lengthy journey by traveling as fast as possible.

No object can reach or exceed the speed of light (roughly 186,000 miles or 300,000 kilometers per second). But well before approaching that threshold, engineering constraints begin to assert themselves. Limited fuel availability and the potential for structural damage will restrict the spacecraft’s peak velocity.

There is no universally accepted upper limit on interstellar flight speeds, but studies tend to converge around 19,000 miles per second (30,000 km/s) – 10% of the speed of light – as a realistic cruise velocity. At this speed, a journey of 10 light-years will take approximately 100 years to complete.

Fueling the dream

Finding a way to accelerate the ship to its target cruise speed is the central challenge facing any would-be alien explorers.

Interstellar space is unforgivingly vast, but the emptiness has some advantages. The lack of atmosphere means there is no aerodynamic drag. So when the ship reaches its cruise speed, it can shut down its propulsion system and coast toward the final destination. Unfortunately, the lack of atmosphere also means there is nothing to slow the ship down prior to arrival. So ideally, the propulsion system would be used for both acceleration at the start of the trip and deceleration at the end.

One of the more exotic propulsion strategies employs high-powered laser beams to push the ship through space. The beam is projected from a stationary array near the travelers’ home planet and directed toward a thin reflective sail attached to the ship. The beam’s photons exert radiation pressure on the sail, propelling the ship forward.

This approach has a major advantage in that it requires no onboard fuel. But the amount of energy and infrastructure needed to operate the laser would be staggering. Also, beamed propulsion provides no mechanism for deceleration. At best, this method could be deployed as part of a hybrid strategy that uses a separate system for deceleration.

A more practical approach is to use rocket propulsion. Rockets generate propulsive force, also known as thrust, by expelling high-velocity exhaust in a rearward stream. By reversing the direction of the exhaust, rockets can also be used to slow the ship down.

Their main disadvantage is that rockets must carry their own fuel in addition to carrying the passengers, the habitat and other life-sustaining systems. The extra load necessitates even more fuel. In other words, you need fuel to transport your fuel. The result is a costly snowball effect that can cause the total fuel requirement to balloon to absurd proportions.

Rocket propulsion can be divided into three broad categories.

Chemical propulsion uses chemical reactions – typically combustion – to extract energy from the bonds between atoms. All human space missions thus far have used chemical propulsion. The problem with this method is that it accesses only a tiny fraction of the energy contained within the fuel.

Consequently, using chemical propulsion on a spacecraft with a cruise velocity of 19,000 miles per second (30,000 km/s) would require more fuel than all the mass in the observable universe.

Antimatter propulsion is theoretically the most efficient option. When antimatter comes into contact with ordinary matter, the two undergo mutual annihilation and 100% of their combined mass is converted into energy. This makes it possible to achieve the same cruise velocity – one-tenth the speed of light – with fuel accounting for less than a quarter of the ship’s total mass. This is science fiction-level fuel efficiency, which makes antimatter an attractive option for interstellar propulsion.

The downside is that antimatter is extremely unstable and difficult to make. To date, particle physicists have produced less than 20 billionths of a gram of antimatter. Moreover, these particles had lifespans lasting only fractions of a second and a price tag in the hundreds of millions of dollars.

Nuclear fusion offers a more viable alternative to antimatter. This approach harvests energy stored inside the nucleus of an atom using the same process that powers the Sun. With current technology, fusion engines remain aspirational, but they could, in theory, produce 10 million times more energy per kilogram than chemical rockets.

An illustration of a cylindrical spacecraft orbiting Earth
NASA has been working to develop nuclear propulsion. This artist’s impression shows what a nuclear-powered rocket could look like. John Frassanito & Associates/Wikipedia

Still, a fusion-powered ship with a cruise velocity of 19,000 miles per second (30,000 km/s) would require fuel equivalent to 150 times the mass of the ship itself.

A delicate balancing act

These numbers assume that our extraterrestrial visitors have figured out how to efficiently convert the energy released by their reactor – whether nuclear fusion or antimatter – into thrust.

Just as importantly, they must be able to create optimized fuel tank structures that are ultra lightweight yet highly secure. Designing the structure of the ship, from the fuel tanks to the hull, would be one of the biggest engineering challenges of the entire mission.

Interstellar space contains a sparse smattering of hydrogen atoms and microscopic grains of cosmic dust. At 19,000 miles per second (30,000 km/s), dust particles would smash into the ship’s hull with the energy of a .22-caliber bullet. The bombardment of hydrogen atoms would produce a violent cascade of radiation that could erode even the most resilient engineering materials.

Surviving the onslaught would require no less than a flying fortress with complex magnetic shielding. This would increase the total mass of the ship, which further drives up the demand for fuel.

This example is just one of the hundreds of delicate design trade-offs that would plague any interstellar vessel. Each individual design requirement acts as a filter, reducing the number of feasible solutions.

Finding a single system that simultaneously satisfies all the requirements is analogous to shopping for a car online. With each new filter you apply – four-wheel drive, black exterior, less than 10,000 miles on the odometer – the number of available options dwindles.

When design requirements are in tension with one another – for example, requiring a structure that is lightweight but also supremely durable – the number of feasible solutions can drop to zero.

No single law of physics prohibits an interstellar voyage to Earth. But the combined effects of hundreds of extreme, often conflicting engineering requirements may render it physically infeasible.

It’s also possible that alien civilizations have discovered novel technologies that outperform anything currently known to humans. But like the examples discussed here, any such technology will inevitably encounter its own engineering hurdles.

The trillion-dollar question

Ultimately, engineering challenges are just some of the many barriers to interstellar travel. Any prospective alien visitors must also have sufficient cognitive ability, technological maturity, physical resources, collective desire and proximity to Earth.

That said, if the stars were to align and an alien vessel made it to Earth intact, it would trigger a torrent of burning questions: Where are they from? What do they want? What are they made of?

But the question that would go furthest in shedding light on the deeper mysteries of the universe is, “How on Earth did they get here?”

Kai James, Professor of Aerospace Engineering, Georgia Institute of Technology

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Kai James poses the unanswerable questions in the last two paragraphs. And how about this statement: “Consequently, using chemical propulsion on a spacecraft with a cruise velocity of 19,000 miles per second (30,000 km/s) would require more fuel that all the mass in the observable universe.“

Your dog-proof home

A post from Penny Martin.

Penny sent me this post and I thought that I would be able to post it before now. However, it seems like the perfect item for today.

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How to Design a Stylish Home That Stands Up to Your Dog

Dog owners who care about décor know the daily tug-of-war between stylish pet-friendly interiors and real-life messes. A sofa that looks perfect can turn into a scratch magnet, clean walls collect nose smudges, and “nice” floors don’t always survive muddy paws, spilled water, or surprise zoomies. The heart of dog-friendly home design is balancing aesthetics and functionality without treating every room like a sacrifice zone. With the right mindset, pet damage challenges can become design boundaries that still leave a home feeling pulled together.

Make 7 Upgrades That Survive Paws, Spills, and Zoomies

If you’ve ever tried to keep a home looking pulled-together while living with a dog who treats the hallway like a racetrack, you already know the goal: durable choices that still feel like you. These upgrades focus on the high-impact trouble spots, floors, walls, entryways, feeding zones, and the yard, so your style holds up to real life.

  1. Choose scratch-resistant flooring in the “runway” zones: If you can’t replace every floor, prioritize the routes your dog actually uses, entry → living room → back door. Look for scratch-resistant flooring with a tough wear layer, and use large, low-pile rugs (with a grippy pad) in corners where dogs pivot and launch. Keep nail trims on a 2–4 week rhythm to reduce micro-scratches, especially on stairs and landings.
  2. Create a paw-and-mud landing strip at the entry: Give dirt and water a place to “stop” before it hits your sofa. Add a washable runner, a closed hamper for dog towels, and a hook or basket for wipes right by the door. A shallow boot tray works great as a water bowl “parking spot,” too, especially for sloppy drinkers.
  3. Install a built-in dog feeding station (even a mini version): A built-in feeding station keeps bowls from wandering, helps contain splashes, and makes the feeding area feel intentional instead of cluttered. For a simple DIY approach, dedicate the bottom of a pantry cabinet or a mudroom nook and add a wipeable surface underneath. If your dog is a messy eater, choose deeper bowls and keep a small handheld vacuum nearby for daily 30-second resets.
  4. Protect walls and corners with “invisible armor”: Paint scuffs and body-oil streaks happen right at nose height and shoulder height. Use a durable, wipeable finish on walls, and add corner guards or wood trim where dogs rub and turn. If you’re renting or not ready to build, a narrow console table along a high-traffic wall can act like a stylish bumper.
  5. Set up a safe zoomie zone with flexible barriers: Instead of correcting your dog all day, manage the space. Use baby gates to block off carpeted rooms, kids’ toy areas, or the staircase when you can’t supervise. This is especially helpful during muddy season, post-bath chaos, or when guests are coming and you need a calm, contained zone fast.
  6. Upgrade fabrics to “cleanable by default” seating: Treat your sofa like performance gear: tight weaves, washable covers, and darker or heathered colors hide fur and drool better than flat, light solids. Keep a throw blanket on your dog’s favorite spot and wash it weekly, your couch stays nicer without starting a daily battle.
  7. Design pet-friendly landscaping for safe outdoor dog areas: Skip yard materials that can hurt paws or tempt chewing, and build a clear path where your dog naturally runs. Penn State Extension suggests flagstones or smooth gravel for pathways, which can reduce paw irritation and keep traffic from killing the grass. Aim for one easy-to-clean potty zone, one shaded “hangout” spot, and fencing you can trust, because outdoor durability counts just as much as indoor style.

Plan New-Home Peace of Mind: Ask About Structural Warranties

Those durability upgrades feel even better when your long-term protection matches the care you’re putting into the build. If you’re building a new dog-friendly home, ask your builder about adding a structural warranty or similar long-term protection, specifically, what’s included, how long it lasts, and how claims work. Solid warranty coverage for new builds can help safeguard the home’s underlying integrity if bigger issues show up later, which matters when everyday dog life adds extra wear and tear. It also helps protect the money you’re investing in pet-friendly choices like durable flooring and built-in features, so you’re not left feeling like you upgraded everything except your peace of mind.

Dog-Proof Design Options at a Glance

This quick comparison helps you choose finishes and features that look intentional, not improvised around your dog. Use it to balance durability, safety, and day-to-day convenience across high-traffic floors, outdoor boundaries, and feeding setups.

OptionBenefitBest ForConsideration
Luxury vinyl plank flooringScratch and spill resistance with many modern stylesBusy kitchens, mudrooms, play zonesCan dent under heavy furniture or sharp impacts
Porcelain tile with matte finishVery tough surface; easy cleanupSlobbery drinkers, rainy-paw householdsHard underfoot; use runners for traction
Real hardwood plus washable runnersClassic look with replaceable protectionLiving rooms where warmth mattersMore visible wear; requires routine refinishing over time
Vinyl-coated chain-link fenceDurable, lower cost, secure containmentLarge yards and strong pullersMore utilitarian look; needs thoughtful landscaping
Built-in feeding station in cabinetryKeeps bowls tidy for a seamless polished lookSmall kitchens and design-forward spacesLess flexible if you change bowl sizes or layout

If traction and easy cleanup are your top priorities, start with flooring and add rugs where your dog sprints or turns fast. If curb appeal matters most, fence style and a discreet feeding zone can make pet features feel fully “designed in.” Knowing which option fits best makes your next move clear.

Dog-Friendly Design FAQs Homeowners Actually Ask

Q: Can a dog-friendly home still protect resale value?
A: Yes, when you choose features that read as timeless upgrades, not pet-only add-ons. Think durable floors in classic tones, washable textiles, and clean-lined storage that hides leashes and toys. Keep any pet-specific elements easy to remove or swap so the home still shows well to non-pet buyers.

Q: How do I keep my floors from looking wrecked in a year?
A: Start with prevention: trim nails regularly and place a textured runner where your dog launches into turns. Use felt pads under furniture and wipe up grit fast, since sand acts like sandpaper. A small “paw station” by the door can cut down on tracked-in dirt.

Q: What’s the simplest way to manage shedding and odors without losing the cozy vibe?
A: Choose low-pile rugs, slipcovers, and throws you can wash weekly, then stick to a quick two-minute daily sweep in high-shed zones. A lidded hamper for dog blankets keeps smells contained. Ventilate after baths and rainy walks so fabrics stay fresh.

Q: Should I build in a feeding area, or keep it flexible?
A: Built-ins look polished, but flexibility often wins for real life. Try a wipeable mat and a tray that can move for cleaning, guests, or a new bowl size. If you love the built-in idea, plan for extra width and a removable insert.

Q: Can my dog’s routine really affect how well my home holds up?
A: Absolutely, because calmer dogs tend to do less damage when they are bored or overstimulated. A simple step is choosing the best foods for your dog with your vet, since nutrition can influence energy and behavior. Pair that with predictable exercise and a designated chew zone to protect your furniture.

Make Stylish, Dog-Ready Design Choices That Last

Living with a dog can feel like a constant tug-of-war between a home that looks good and one that can handle real life. The calmer path is a mindset of integrating pets into home life, planning for paws, fur, and play while still aiming for stylish and functional living. When that approach guides confident dog owner design choices, harmonious dog-friendly homes become easier to maintain, not harder to enjoy. Design for the dog you live with, and style will follow. Choose one long-term pet-friendly design change to start this week, and let it set the tone for the rest of your space. A home that supports both of you builds daily ease, deeper connection, and resilience for the years ahead.

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That is an excellent set of recommendations, many of which would not have occurred to me. Neither to Jeannie, who has loads more experience of looking after dogs than I have.

So, thank you, Penny and I look forward to your next ‘guest’ post.

The Emperor’s New Mind

I have finished this fabulous book.

The Emperor’s New Mind: Concerning Computers, Minds and The Laws of Physics

Book by Roger Penrose

Here is a summary of the book that is first, a very deep read, and, second, full of detailed mathematics that were beyond me. I just skipped those parts. However, it is an incredible book and one that has extended my knowledge in so many ways. I think that it isn’t going too far to say that it has amended my knowledge tremendously and I am so glad to have read it, even at the age of 81.

If you wish, you may refer to my thoughts when I first obtained the book, written down on April 14th.

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The Emperor’s New Mind (1989) by Roger Penrose argues that human consciousness involves non-computable processes, meaning a computer can never fully replicate the human mind, even if it can simulate its functions. Penrose uses Gödel’s incompleteness theorems and quantum mechanics to support his view, suggesting that consciousness arises from physical processes in the brain that are not algorithmic, and that a deeper understanding of physics, possibly involving quantum gravity, is needed to explain the mind. The book explores the “mind-body problem” and challenges the idea that all thinking is computation, proposing that human understanding can grasp truths that formal systems cannot. 

Key arguments and concepts

  • Gödel’s Incompleteness Theorems: Penrose argues that human mathematicians can see the truth of certain mathematical statements that a formal system (like a computer program) cannot prove, demonstrating a non-computable aspect of human thought. 
  • Non-computability: He posits that certain mental activities, like mathematical insight, are inherently non-algorithmic and cannot be simulated by a computer, even a powerful one. 
  • Quantum mechanics and consciousness: Penrose suggests that consciousness is linked to quantum mechanical processes in the brain, specifically involving microtubules, a theory he later developed further in Shadows of the Mind. 
  • Critique of Strong AI: The book challenges the “strong AI” hypothesis that a sufficiently complex computer can achieve genuine consciousness, arguing that it misunderstands the nature of human understanding. 

Reception and legacy

  • The book won the 1990 Science Book Prize. 
  • It sparked debate and collaboration, notably with Stuart Hameroff, leading to the “orchestrated objective reduction” (Orch OR) theory of consciousness. 
  • It remains a significant work in the philosophy of mind, artificial intelligence, and the physics of consciousness, influencing discussions on the limits of computation and the nature of the mind. 

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Penrose won the Science Book Prize in 1990 for The Emperor’s New Mind.

I am not surprised.

The unacceptable side of technology

The right to repair one’s own technology products is under attack.

I hadn’t really thought of this before now. I am speaking of an article last Friday that was published by The Conversation.

A large part of me is very open to the ways that technology is helping me. I presume that I am far from being alone.

Here is that article that questions the way things are.

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Today’s bans on DIY repairs of everything from cell phones to tractors grew out of Hollywood’s fear of videotaping

Betamax video recorders like this one helped set off a chain of events leading to bans on repairing your own devices. Steve Jurvetson/Wikimedia Commons, CC BY

Oana Godeanu-Kenworthy, Miami University

If you have ever tried to repair something, realized that it was beyond your financial or technical means, and ended up buying a new one, you are not alone. Repairing electronics and household appliances has not been a real option in the United States for decades now, particularly for items that have proprietary software in them.

Absurd situations have proliferated. It can cost about the same to buy a new printer as it does to replace the ink cartridge. The U.S. Department of Defense cannot repair the weapons systems it purchases because the intellectual property rights remain with the manufacturer. John Deere, the farming equipment company, doesn’t allow farmers to access the software needed to repair their own combines and tractors because, while the purchase covers the physical machinery, it does not cover the software.

One consequence, in addition to cost and frustration for consumers, is environmental harm. The U.S. is the world’s second producer of electronic waste after China, to the tune of about 43 lbs (19.5 kg) of electronic waste annually per person. Only 25% of this e-waste is recycled.

The right-to-repair movement emerged in response, calling for people to be able to repair what they purchase, or have third parties do the repair work, without unnecessary financial, legal or technical barriers. Right to repair seems to be a rare area of bipartisanship in Congress. The Warrior Right to Repair Act – introduced in 2025 by a Democrat – and the Repair Act – introduced by a Republican – are two ongoing legislative initiatives to create a federal legal framework that would make it easy and cheap for American users to repair their devices. Both bills are fiercely opposed by industry groups.

As a scholar of American culture, I found through my research that the origins of the legal and technical obstacles to product repairs lie in debates in the 1980s over new media and copyright guardrails.

Hollywood and VCRs

The rapid rise and popularity of video cassette recorders, or VCRs, in the late 1970s transformed films and TV shows from transient experiences into tangible consumer goods. As I show in my book, “Videotape,” despite the potential for extra revenue, Hollywood was alarmed by the fact that users were now able to copy films on videotape, and tried to stop the technology. Today’s repair bans are part of that story.

The first U.S. copyright provisions were embedded in the 1790 Constitution. Over time, the law was amended to include new technologies, but at the core of future legal arrangements remained the initial intent: to protect the financial rights of creators while giving enough access to information for society as a whole to progress.

Until the second half of the 20th century, the American doctrine of fair use, which allows the unlicensed use of protected works under specific conditions, allowed judges to prevent copyright law from negatively affecting public interest. Organizations such as public libraries, book clubs, universities and news organizations benefited from this legal approach. The concept was codified into American law in the Copyright Act of 1976.

When the film studios took Sony to court to stop the production and sale of video recorders in 1976, they argued that Sony’s product encouraged copyright infringement. But the U.S. Supreme Court ruled in 1984 that taping TV content for personal use did not violate copyright law, expanding the understanding of fair use.

The industry then focused on finding a technological solution to the piracy problem and on securing stricter legal protections for its products.

They identified the digital versatile disc, or DVD, as a safer alternative to the VHS tape. Initially, the DVD was a read-only format. It took a few more years of engineering before affordable recording was possible. Even then, the process was far more complicated for users than videotape recording. In 1997, barely one year after the video disc was launched, all of the Motion Picture Association of America member studios joined the DVD Forum, collectively adopted the new format and started to phase out films released on videotape. https://www.youtube.com/embed/46RDkiy5h3U?wmode=transparent&start=0 Manufacturers use several tactics to block consumers and third-party repair shops from fixing their products.

Copyright and virtual locks

Then came digital rights management. Collectively, the term refers to the battery of technological tools that the industry developed in order to control user access to content. These include encryption software and various forms of authentication or enforcement software that limit which types of digital activities users can perform. For instance, some mechanisms block the option to download or share a digital file.

The Digital Millennium Copyright Act, or DMCA, signed into law by President Bill Clinton in 1998, provided the broad legal framework that allowed these technological locks to expand far beyond entertainment, including to software. The Digital Millennium Copyright Act reflected a new alignment in interests between the entertainment and software industries. It increased existing penalties for copyright infringement online and criminalized any technology used to bypass technological locks. The law was adopted although at the time – and since then – critics warned that it could stifle innovation and increase costs for consumers.

Since 1998, more and more consumer products, from toys to dishwashers, use microchips and proprietary software protected by copyright. Because of the Digital Millennium Copyright Act, third party repairers cannot alter or bypass the proprietary software. If they did so, they would be liable for infringing the manufacturer’s intellectual property rights, as is the case for John Deere farm equipment. Some electronics are even designed to make tampering with the product impossible.

Manufacturers maintain that only they or authorized personnel can and should repair their products. These repairs are often quite costly. When getting a product repaired becomes almost as expensive as buying a new one, many consumers will choose to buy and throw repairable items away.

Rising resentment over repair bans

Technology tends to outpace existing legal arrangements. With over 80% of Americans supporting the right to repair, it remains to be seen when or if American law will catch up with the unexpected consequences of a law meant to protect the intellectual rights of the creative industries, but which is now hurting consumers’ pocket books.

Oana Godeanu-Kenworthy, Teaching Professor of American Studies, Miami University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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The end of that article points out that more than 80% of Americans support the right to repair and, I guess, that support extends far beyond the USA.

Indeed, a quick online search found that in the UK an organisation, Restart, had a website on the subject. Here is a little of what they said;

“The last few years have been really exciting for the Right to Repair in many countries outside the UK. Around the world we’ve seen people get access to more repairable and longer lasting products, cheaper repair options and better information about product repairability. As a result, repair is helping tackle climate change, reduce waste, lower living costs, support communities and create green skilled jobs in more places than ever.“

Then another search found out that the Eurpoean Commission had a Right to repair law in place. It was introduced in 2024. Here’s how it starts:

“The new rules reinforce the right to repair, aim to reduce waste and bolster the repair sector by making it easier and more cost-effective to repair goods.“

So, hopefully, Oana, the teaching professor at Miami University, can establish a new law that will give American consumers the right to replair their technology belongings.

Knowledge

The following is an excellent message.

The Conversation yet again have published an excellent post. It is about becoming a more informed person.

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Most people don’t know what they don’t know, but think they do – correcting your metaknowledge can make you a better teacher and learner

The ability to say ‘I know that I know nothing’ could be considered a sign of wisdom. Nicolas-André Monsiau/Pushkin Museum of Fine Arts via Wikimedia Commons

Tommy Blanchard, Tufts University

Do you know what the Apple logo looks like?

Chances are, you think you do. It’s ubiquitous and iconic. How could you not know it?

But when tested, it turns out very few people can remember all the features of the logo. One study of 85 people found that only about half could pick the correct logo out of a lineup of similar ones. And only one person could correctly draw it.

This isn’t an isolated example. A classic study from 1979 found that people similarly couldn’t draw a penny accurately or pick out a correctly drawn penny from incorrect ones.

People aren’t just bad at remembering things they see all the time, but also in actually knowing how they work. In a 2006 study, many people made significant errors when drawing a bicycle, like putting the chain around the front wheel as well as the back wheel. More than just a forgotten detail, putting the chain around both wheels shows a deeper misunderstanding of how a bicycle works. A bicycle with a chain around both wheels wouldn’t be able to turn.

Illustration of bike with different components labeled
Do you truly know how a bicycle works? Al2/Grandiose via Wikimedia Commons, CC BY-SA

It turns out people’s knowledge of how the world works is often fragmented and sketchy at best. They systematically overestimate their understanding of everyday devices and natural phenomena. People will tend to give themselves high ratings on how well they understand something, such as how bicycles or zippers work. But when they’re asked to actually explain the mechanics of these objects, their ratings of their understanding typically drop.

Just like how your knowledge of the world around you is imperfect, your knowledge about your own knowledge – also called metaknowledge – is often flawed. My field of cognitive science has been uncovering various gaps in human metaknowledge for decades.

If people are systematically overconfident about how well they understand things, why don’t they notice when they don’t understand something? And what can people do to better recognize the limits of their own knowledge?

Why you think you know more than you do

Researchers have identified several factors behind people’s overconfidence in their knowledge.

One is that people confuse environmental support with understanding: The information is out in the world but not actually in your head. With a bicycle or a zipper, all of the parts are visible to you, and you may confuse this transparency for an internal understanding of how they work. But until you go to use that knowledge by attempting to explain how they work, you may not recognize that you don’t understand how those parts interact.

A second factor is confusing different levels of analysis. People can often describe how something works at a very high level. You know that the engine of a car makes the car go, and the brakes slow and stop the vehicle. But confidence in your high-level understanding of the car may bias you to think you also have a good grasp of the finer details, like how the engine pistons and brake pads work.

Additionally, people can be blind to the ways their knowledge shapes their own perception. In one study, researchers had participants tap out the tune to a popular song. On average, the tappers thought listeners would be able to identify the song about 50% of the time. But when listeners had to identify the tapped song, they actually could identify it only 2.5% of the time. The tappers didn’t realize how much their knowledge was making identifying the song seem easy to them.

A teacher talks to a student before a chalkboard wall filled with equations, chemical structures and graphs
Intellectual humility can help you see your expert blind spot. Vitaly Gariev/Unsplash, CC BY-SA

This disconnect has consequences beyond whether someone else can understand your Morse code version of a song. When teaching people, whether in formal classroom settings or through casual mentorship, you can sometimes have an expert blind spot: the inability to recognize the difficulties beginners face when learning something you have expertise in.

Building expertise often involves internalizing knowledge to the point where it becomes invisible to you. You draw on knowledge you don’t realize you have, making it hard to relate to learners who lack this knowledge – and, of course, hard for learners to relate to your teaching. You might have experienced this when you’ve gotten partway through explaining something, only to realize you’ve been using jargon you forgot isn’t common knowledge and lost your listener.

How to address metaknowledge failures

Your metaknowledge can fail in two directions: You can think you know more than you do, and you can be blind to how much you’re relying on knowledge you do have. Each calls for a different response to correct it.

When you’re overconfident in your knowledge, the remedy is using that knowledge. You’ll quickly realize how much you actually understand and dial down your confidence. Challenging yourself to actually try to walk through how something works is a great exercise in intellectual humility – that is, recognizing that you may be wrong – and can keep you from getting out over your skis.

Building a greater appreciation for what you know is more difficult. You can’t simply unlearn what you’ve internalized. But what this challenge shows is that, to some extent, knowing a subject and knowing how to teach it are two separate skills. Some experts are great teachers, but not simply by virtue of being experts. Recognizing that you have to approach teaching with humility, and that your expertise doesn’t automatically make you a skilled teacher, can go a long way toward making you a better teacher and mentor.

These aren’t easy and quick fixes to failures of metaknowledge. Both require ongoing intellectual humility and a willingness to distrust your own confidence. But acknowledging the fallibility of your own metaknowledge is a good place to start.

Tommy Blanchard, Research Associate in Cognitive Science, Tufts University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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This article is of particular interest for me. Because a few years ago, I had a biking accident at the local Merlin (OR) rail crossing. I banged my head badly and was unconscious for about eight minutes. Later on the surgeon who operated on my head said that I was lucky to be alive but that from here on my memory would be poor.

I work very hard to try and remember the items that I want to. And without my pocket book to write things down, I would be so much more forgetful.

Connecting with the natural world

Please, please, let us remember this.

It is my habit to listen to BBC Radio 4 in the early morning. Especially The World at One from 13:00 to 13:45 BST and then, usually, the 15-minute programme transmitted immediately afterwards.

Yesterday, that programme was the start of a new ten-part series called RINSED. Here’s how it is described on the website:

1. The Bridge

Rinsed.

 Episode 1 of 13

After watching their local river grow murky and lifeless, two retired neighbours decide to take on the water industry and its regulators. The unlikely sleuths begin a ten-year battle to clean up our rivers.

On the banks of the River Windrush in Oxfordshire, Kate Lamble meets campaigners Ash Smith and Peter Hammond

Reported and presented by Kate Lamble 
Producer: Elle Scott
Sound Design: Andy Fell
Executive Producer: Joe Kent 
Commissioning Executive: Tracy Williams
Commissioning Editor: Dan Clarke 

Rinsed is a BBC Studios production for BBC Radio 4

Here is the link to the programme.

Geo. Monbiot’s Grim Message

Action regarding the climate crisis.

The following essay from George Monbiot is a difficult read but it is also a necessary read.

With the news that the polar ice caps are retreating, just read yesterday: “Polar ice caps and sheets are shrinking at alarming rates due to global warming, with Arctic sea ice decreasing by over 12% per decade and polar ice sheets losing 7,560 billion tonnes of ice between 1992 and 2020. Greenland and Antarctica are losing hundreds of billions of tons of ice annually, significantly contributing to rising sea levels. [1, 2, 3, 4]”

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Alternating Current

Posted on 29th April, 2026

If this crucial circulation system shuts down, the civilisational impacts will be irreversible. So why isn’t it a top priority?

By George Monbiot, published in the Guardian 23rd April 2026

The poor and middle pay taxes, the rich pay accountants, the very rich pay lawyers – and the ultra-rich pay politicians. It’s not an original remark, but it bears repeating until everyone has heard it. The more money billionaires accumulate, the greater their control of the political system – which means they pay less tax, which means they accumulate more, which means their control intensifies.

They reshape the world to suit their demands. One of the symptoms of the pathology known as “billionaire brain” is an inability to see beyond their own short-term gain. They would sack the planet for a few more stones on the pointless mountain of wealth. And we can see it happening. Last week delivered the biggest news of the year so far, perhaps the biggest news of the century. But partly because billionaires own most of the media, most people never heard it. We might find ourselves committed to a civilisation-ending event before we even learn that such a thing is possible.

The news is that the state of a crucial oceanic circulation system has been reassessed by scientists. Some now believe that, as a result of climate breakdown changing the temperature and salinity of seawater, it is more likely than not to collapse. This system – known as the Atlantic meridional overturning circulation (Amoc) – delivers heat from the tropics to the North Atlantic. Recent research suggests that if it shuts down, it could cause both a massive drop in average winter temperatures in northern Europe and drastic changes in the Amazon’s water cycles. This could help tip the rainforest into cascading collapse and trigger further disaster.

Amoc’s shutdown is likely also to cause an acceleration of sea level rise on the east coast of the US, threatening cities. It could also raise Antarctic temperatures by roughly 6C and release a vast pulse of carbon currently stored in the Southern Ocean, accelerating climate catastrophe.

Even when the countervailing effects of generalised global heating are taken into account, a further paper proposes, the net impact in northern Europe would be periods of extreme cold – including events in which temperatures in London fall to -19C, in Edinburgh to -30C and in Oslo to -48C. Sea ice in February would extend as far as Lincolnshire. Our climate would change drastically, with the likelihood of far greater extremes, such as massive winter storms. Rain-fed arable agriculture would become impossible almost everywhere in the UK.

This shift, on any realistic human scale, would be irreversible. Its speed is likely to outrun our ability to adapt. Amoc shutdowns, driven by natural climate variability, have happenedbefore. But not in the era of large-scale human civilisation.

The first paper proposing that Amoc might have an on-state and an off-state was published in 1961. Since then, many studies have confirmed the finding and explored potential triggers and likely implications. Until recently, Amoc collapse caused by human activity fell into the category of a “high impact, low probability” event, devastating if it happens, but unlikely to occur.

Research over the past few years prompted a reassessment: it began to look more like a “high impact, high probability” event. Now, in response to last week’s paper, Prof Stefan Rahmstorf – perhaps the world’s leading authority on the subject – says the chances of a shutdown look like “more than 50%”. We could pass the tipping point, he says, “in the middle of this century”.

So why is this not all over the news? Why is it not the top priority for the governments that claim to protect us from harm? Well, in large part because oligarchic power has championed a model of climate impact that bears little relation to reality: that is, they have a hypothesis about how the world works that is completely detached from scientific findings. This model underpins official responses to the climate crisis.

It began with the work of the economist William Nordhaus, who sought to assess the economic effects of global heating. His modelling suggests that a “socially optimal” level of heating is between 3.5C and 4C. Most climate scientists see a temperature rise of this kind as catastrophic. Even 6C of heating, Nordhaus suggests, would cause a loss of just 8.5% of GDP. Climate science suggests it would look more like curtains for civilisation.

As the eminent economists Nicholas Stern, Joseph Stiglitz and Charlotte Taylor have argued, the mild effects Nordhaus forecasts are merely artefacts of the model he has used. For example, his modelling assumes that catastrophic risks do not exist and that climate impacts rise linearly with temperature. There is no climate model that proposes such a trend. Instead, climate science forecasts nonlinear impacts and greatly escalating risk.

The likely impacts of high levels of heating include the inundation of major cities, the closure of the human climate niche (the conditions that sustain human life) across large parts of the globe, the collapse of the global food system and cascading regime shifts – that is, abrupt transitions in ecosystems – releasing natural carbon stores, potentially leading to a “hothouse Earth” in which very few survive. Never mind a few points off GDP: there would be no means of measurement and scarcely an economy to measure.

Bizarrely, the modelling also applies discount rates to future people: their lives, it assumes, are worth less than ours. In other words, it has taken a method used to calculate returns to capital and applied it to human beings. As the three economists point out, “it is very difficult to find a justification for this in moral philosophy.” Moreover, climate impacts disproportionately affect the poor – but under the models, their lives are also priced down.

Unsurprisingly, models of this kind, Stern, Stiglitz and Taylor note, have been seized on by “special interests” such as the fossil fuel industry to argue for minimal responses to the climate crisis. And it’s not just the oil companies. Bill Gates, who claims to want to protect the living planet, has given $3.5m (£2.6m) to a junktank run by Bjorn Lomborg, who has built his career on promoting Nordhaus’s model, thus helping to downplay the need for climate action. Nordhaus was awarded the Nobel Memorial prize for economics for his pernicious nonsense – and it is deeply embedded in government decision-making.

A billionaire death cult has its fingers around humanity’s throat. It both causes and downplays our existential crisis. The oligarchs are not just a class enemy but, as they have always been, a societal enemy: a few thousand people can destroy civilisations. It’s the billions v the billionaires, and the stakes could not possibly be higher.

http://www.monbiot.com

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Until I came to live in the the USA permanently, in 2010, I used to live in South Devon, near Totnes. Thus the AMOC was very familiar to me and the local population. AMOC stands for Atlantic Meridional Overturning Circulation. Much more information on AMOC may be read on the WikiPedia site.

Although the future of the AMOC is uncertain, many scientists are concerned that the AMOC will weaken.

The above article by George Monbiot is potentially frightening. As Monbiot says at the end; “… a few thousand people can destroy civilisations.“

What we need is a few thousand people to make this the number one priority! Not tomorrow but today!

An eclipse seen from space

This is beautiful.

I have always been interested in the space flights of the astronaughts. I am sure that I join millions of others who feel the same.

So this article by Deana L. Weibel, Professor of Anthropology at Grand Valley State University is terrific.

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Seeing an eclipse from Earth is awe‑inspiring – for astronauts seeing one from space, the scene was even more grand

During a total solar eclipse, the Sun is barely visible behind the Moon. Roger Sorensen

Deana L. Weibel, Grand Valley State University

The astronauts on Artemis II’s trip to the Moon in April 2026 didn’t just have an amazing journey through space. They also saw something extraordinary. They were the first humans to see a total solar eclipse from space.

A solar eclipse happens when the Moon moves in front of the Sun. In a total eclipse, the Sun’s central disc is covered completely.

From Earth, the circle of the Sun is about the same size as the circle of the Moon. With the bright circle blocked, you can see the undulating rays of the Sun’s corona, or outer atmosphere, that are normally too dim to be observed.

Moon covering most, then all, then most of the Sun
Composite image of moments before, during and after totality. NASA/Aubrey Gemignani

I’m a cultural anthropologist who studies awe-inspiring aspects of space exploration. I have been lucky enough to have seen two total solar eclipses. The first one was in Nebraska in 2017, the second in Indiana in 2024.

During my second total eclipse, the period of totality – that short span when you can remove your protective glasses and look directly at the eclipse – lasted close to 4 minutes. I saw waves of diffuse light snaking around an ink-black hole in the sky. It looked very wrong – almost alien.

On Aug. 12, 2026, there will be another total solar eclipse, visible only from Greenland, Iceland, Spain and the Balearic Islands of the Mediterranean. Some fortunate viewers in Spain and nearby islands may see the eclipse just before sunset, low on the horizon. The Moon illusion, a phenomenon where the Moon looks bigger when it’s near the horizon, might make this eclipse look unusually large.

Unusual eclipse perspectives

Astronauts will occasionally also have less common eclipse experiences. I interviewed one I call by the pseudonym “Jackie” in my research about astronauts’ experiences of awe. She was part of an astronaut training group that did a flight exercise during a total solar eclipse.

Jackie and her squad flew their jets in the shadow of the Moon. This lengthened their time in totality because they could follow and stay within the shadow. Jackie was most impressed with how the Sun’s corona seemed to shift and ripple.

“It’s not static … it’s alive,” she told me.

On April 6, 2026, the astronauts of NASA’s Artemis II mission saw another kind of unusual eclipse as they flew around the Moon. At one point during their flight, the Moon and the spacecraft aligned so that the Moon was directly between them and the Sun, blocking the Sun’s disk in a way that looks very different from what we see on Earth.

Astronaut Victor Glover said it felt like they “just went sci-fi.” https://www.youtube.com/embed/YLjPci5bo1k?wmode=transparent&start=0 ‘An impressive sight’: The Artemis II crew were the first humans to observe a solar eclipse from near the Moon.

The astronauts were so close to the Moon that the Moon looked bigger than the Sun and hid more of its bright circle. Earth was also in view, and sunlight reflected from the Earth onto the Moon in a phenomenon NASA calls “earthshine.” This dim light is very similar to the moonlight that shines on the Earth at night.

Imagine the Sun hidden behind the Moon, creating a hazy halo around the Moon’s edges. At the same time, faint light reflected from Earth softly illuminates the Moon, revealing mountains and craters in a dim twilight. Now imagine this striking scene lasting 54 minutes.

This sight was, without a doubt, one of the most unusual eclipses ever seen by human eyes.

Although Artemis’ astronauts are trained to think scientifically, this experience propelled them into a state of awe. They talked openly about how their brains were “not processing” what they observed. While NASA kept them busy with a variety of tasks, the sound of emotion and excitement in their voices as they broadcast live from their lunar flyby was unmistakable.

An eclipse visible from space - the Moon is shown shadowed with some sunlight visible behind it, and part of the Orion capsule shown off to the left.
The Moon during a solar eclipse on April 6, 2026, photographed by one of the Orion spacecraft’s cameras during Artemis II. Earth is reflecting sunlight at the left edge of the Moon, called ‘earthshine.’ NASA

The psychology of awe

Researchers have studied the effects of awe on the human brain, including awe felt during solar eclipses. Moments of wonder like these can transform how you feel and even how you think, making you more thoughtful and open-minded.

In my own work I’ve found these experiences can change how astronauts understand their own place in the universe.

One astronaut said she gained an awareness of the fragility of our planet that now shapes everything she does, while another described becoming more curious after returning to Earth. A third said the awe he experienced in lunar orbit changed his understanding of time and infinity.

Space travel creates many opportunities for awe, but a solar eclipse from behind the Moon, as Mission Commander Reid Wiseman put it, required “20 new superlatives.”

It’s an experience most of the earthbound eclipse-chasers heading to Greenland or Iceland or Spain this summer will only dream about. Whether eclipses happen in space or on Earth, though, close encounters with the grandeur of our universe can make you feel profoundly human.

Deana L. Weibel, Professor of Anthropology, Grand Valley State University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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In this difficuly world at present, this is a perfect article. As was written, “…. the awe he experienced in lunar orbit changed his understanding of time and infinity.“

Picture Parade Five Hundred and Twenty-One

More NASA images.

And what images.

NASA celebrates Hubble’s 36th anniversary with a new image of the Trifid Nebula, a star-forming region it first captured in 1997. The telescope leveraged almost its full operational lifetime to show us changes in the nebula on human time scales with an improved camera.
NASA, ESA, STScI; Image Processing: Joseph DePasquale (STScI)

There is more information on the NASA website.

Now a YouTube video.

What terrific images from Hubble.

Artemis images

A unique record taken by the crew.

Human-created photos of this historic mission cannot be replace by articificial intelligence (AI).

This is the reason I am republishing an article from The Conversation.

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Artemis II crew brought a human eye and storytelling vision to the photos they took on their mission

Astronaut Jeremy Hansen takes a picture through the camera shroud covering a window on the Orion spacecraft. NASA

Christye Sisson, Rochester Institute of Technology

In early April 2026, the Artemis II mission captivated me and millions of people watching from across the world. The crew’s courage, skill and infectious wonder served as tangible proof of human persistence and technological achievement, all against the mysterious backdrop of space.

People back on Earth got to witness the mission through remarkable photos of space captured by astronauts. Images created and shared by astronauts underscore how photography builds a powerful, authentic connection that goes beyond what technology alone can capture.

As a photographer and the director of the Rochester Institute of Technology’s School of Photographic Arts and Sciences, I am especially drawn to how these photographs have been at the center of the public’s collective experience of this mission.

In an era when image authenticity is often questioned and with the capabilities of autonomous, AI-driven imaging, NASA’s choice to train astronauts in photography has placed meaning over convenience and prioritized their human perspectives and creativity.

Capturing space from the crew’s perspective

Photography was not originally placed as a high priority in NASA’s Apollo era. The astronauts only took photographs if they had the chance and all their other tasks were complete.

An image of the entire Earth from space.
‘The Blue Marble’ view of the Earth as seen by the Apollo 17 crew in 1972. NASA

Thanks largely in part to public response to those images from Apollo, including “Earthrise” and the “Blue Marble” being widely credited for helping catalyze the modern environmental movement, NASA shifted its approach to utilize photography to help capture the public’s imagination by training their astronauts in photographic practices.

The Artemis II mission’s photographs have helped cut through the increasing volume of artificially generated images circulating on social media. NASA’s social media releases of the crew’s photographs have garnered thousands of shares and comments.

This excitement could be explained by the novelty of photos from space, but these images also distinguish themselves as products of astronauts experiencing these sights and interpreting them through their photographs. These differences require an important distinction around where technology ends and humanity begins.

An astronaut looking out the window of the Orion spacecraft, where the full moon is visible in space.
NASA astronaut Reid Wiseman watches the Moon from one of the Orion spacecraft’s windows. NASA

Human perspective versus AI tools

Photography has long integrated AI-powered software and data-driven tools in a variety of ways: to process raw images, fill in missing color information, drive precise focus and guide image editing, among others. These modern technological assists help human photographers realize their vision.

Artificial intelligence is also increasingly capable of operating machinery competently and autonomously, from cars to drones and cameras.

And AI can generate convincing, realistic images and videos from nothing more than a text prompt, using readily available tools.

Researchers train AI to mimic patterns informed by millions of sample images, and the algorithm can then either take or create a photograph based on what it predicts would be the most likely version of a successful, believable image.

Human-created photos are rooted in direct observation, intent and lived experience, while AI images – or choices made by AI-driven tools – are not. While both can produce compelling and believable visuals, the human photographs carry emotional power because the photographer is drawing from their experiences and perspective in that moment to tell an authentic story.

Artemis II photographs resonate, not only because they are historic, but because they reflect the deliberate choices and intent of a human being in that specific moment and context. The exposure, camera setting, lens choice and composition are all dictated by the astronaut’s vision, skill, perspective and experience. Each image is unique in comparison with the others. These choices give the images narrative power, anchoring them in human perspective.

The Earth shown partially shadowed beyond the Moon in space
NASA’s ‘Earthset’ photo captured by the Artemis II crew. NASA

Images to tell a story

Photographers choose what to include in the final version of their image to tell a story. In the Artemis II images, this human perspective comes out. In the “Earthset” photo, you see a striking juxtaposition of the Moon’s monochromatic, textured surface in the foreground against a slivered, bright Earth.

The choice to include both in the frame contrasts these objects literally and figuratively, inviting comparison. It creates a narrative where Earth is contrasted against the Moon – life is contrasted against the absence of it.

Another photo shows the nightside of the whole Earth, featuring the Sun’s halo, auroras and city lights. The choice to include the subtle framing of the window of the capsule in the lower left corner reminds the viewer where and how this image was captured: by a human, inside a capsule, hurtling through space. That detail grounds the photograph in the human perspective.

Both photos are reminiscent of Earthrise and the Blue Marble. These past images hold a place in the global collective consciousness, shaped by a shared historical moment.

The Artemis II photographs are anchored in this collective moment of lived human experience, yet also shaped by each astronaut’s viewpoint. The crew’s unique perspectives exemplify photography’s transformative power by inviting viewers to engage emotionally and intellectually with their journey. These photographs share the astronauts’ awe and wonder and affirm the value of human creativity and its ability to connect us in a captured moment.

Christye Sisson, Professor of Photographic Sciences, Rochester Institute of Technology

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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I am going to repeat a sentence towards the end of the article: “These past images hold a place in the global collective consciousness, shaped by a shared historical moment.”

That global collective consciousness!