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Cancer treatment has advanced significantly, focusing on targeted approaches that destroy tumor cells while sparing healthy tissue. Researchers have developed magnetic nanoparticles that can be directed to tumors using a magnet and then heated with a laser to destroy cancer cells. In mouse models, this targeted technique successfully eliminated tumors entirely. This innovative method provides a more precise and less toxic alternative to traditional treatments, paving the way for more effective cancer therapies.

Researchers have developed the Automatic Process Explorer (APE), an approach that enhances our understanding of atomic and molecular processes. By dynamically refining simulations, APE has uncovered unexpected complexities in the oxidation of Palladium (Pd) surfaces, offering new insights into catalyst behavior.

Urban highways promise to get people to their destinations faster -- and bring them together. But at the same time, they reduce social connections between people within the city, especially at distances of less than 5 km, according to a new study.

A new study revealed that atmospheric gravity waves play a crucial role in driving latitudinal air currents on Mars, particularly at high altitudes. The findings, based on long-term atmospheric data, offer a fresh perspective on the behaviors of Mars' middle atmosphere, highlighting fundamental differences from Earth's. The study applied methods developed to explore Earth's atmosphere to quantitatively estimate the influence of gravity waves on Mars' planetary circulation.

Researchers have created washable and durable magnetic field sensing electronic textiles -- thought to be the first of their kind -- which they say paves the way to transform use in clothing. This technology will allow users to interact with everyday textiles or specialized clothing by simply pointing their finger above a sensor.

Researchers have created washable and durable magnetic field sensing electronic textiles -- thought to be the first of their kind -- which they say paves the way to transform use in clothing. This technology will allow users to interact with everyday textiles or specialized clothing by simply pointing their finger above a sensor.

The mystery of Dark Matter endures. Despite sixty years of observation and research, scientists still haven't isolated the particle that accounts for roughly 85% of the Universe's mass. However, ongoing experiments and studies have provided insight into how this mysterious mass works. For instance, a research team led by a member of the Tokyo Metropolitan University relied on a new technique that has set new limits on the lifetime of Dark Matter (DM), bringing scientists a step closer to resolving this cosmological mystery.

Scientists have developed a biorobotic arm that can mirror human tremors, such as those experienced by individuals that live with Parkinson's disease. Artificial muscles on either side of the forearm contract and relax to suppress the involuntary shaking of the wrist and hand. The researchers see their biorobotic arm not only as a platform for other scientists in the field to test new ideas in exoskeleton technology. The arm also serves as a test bed to see how well artificial muscles known as HASELs can one day become the building blocks of wearable devices. The vision is to one day develop a sleeve that tremor patients can comfortably wear to be able to better cope with everyday tasks such as holding a cup.

Scientists have developed a biorobotic arm that can mirror human tremors, such as those experienced by individuals that live with Parkinson's disease. Artificial muscles on either side of the forearm contract and relax to suppress the involuntary shaking of the wrist and hand. The researchers see their biorobotic arm not only as a platform for other scientists in the field to test new ideas in exoskeleton technology. The arm also serves as a test bed to see how well artificial muscles known as HASELs can one day become the building blocks of wearable devices. The vision is to one day develop a sleeve that tremor patients can comfortably wear to be able to better cope with everyday tasks such as holding a cup.

THIS ARTICLE IS DEDICATED TO MY COLLEAGUE MATTHEW COBB, WHO IS BEING DRIVEN CRAZY BY UNHINGED PIECES ON “DE-EXTINCTING” THE WOOLY MAMMOTH

The push to re-create the extinct Woolly Mammoth (Mammuthus primigenius) may be the biggest waste of money in decades, and for several reasons. First, the people behind this are misleading the public by making us think that they’re going to give us a real woolly mammoth instead of a hairy and (perhaps) cold-tolerant Asiatic elephant, which is what they’re really trying to make. It doesn’t help that credulous and ignorant journalists can’t even see through this.

Second, the endeavor to even make a hairy elephant (they propose to put manufactured mammoth genes with sequences derived from frozen mammoths, into a fertilized elephant egg, and then implant it into an
Asiatic elephant), faces so many obstacles that it seems nearly impossible. And even if it were possible, you’d need to make at least two faux mammoths so they could create a lineage. And where would they live, since real woolly mammoths were denizens of the chilly tundras of northern Asia? (That’s why they had hair.) What would they eat? Asiatic elephants don’t eat the kind of stuff on the tundra, and aren’t equipped to process it, but they’re not going to change behavior and physiology genes.

As I reported yesterday, this ridiculous project is making the news again because, yes, scientists have created a “woolly mouse” by injecting nine genes known to influence hair color and texture IN MICE into mouse stem cells and implanting the lot in mice. They got fuzzier mice, but apparently not the ones shown below, which are in the press release. What they really got are mice less hairier than those shown in the press (see below).

Of course, you can also breed mice that look like this, but we can’t breed Asiatic elephants, though that would be more likely to produce a faux mammoth, because their generation time is too long.  And, as I said, it’s a hell of a lot easier to make transgenic mice than transgenic elephants.  As one wag tweeted about this ludicrous experiment on mice, which is supposed to be a precursor to the Mammoth Project:

GIVE THEM TRUNKS YOU COWARDSwww.theguardian.com/science/2025…

— Marc Dionne (@marcsdionne.bsky.social) 2025-03-04T18:05:25.420Z

. . . AND BIG TUSKS, TOO!

Both Matthew and I have criticized this project for its pretended aims as well as its impossibility (see my posts here, as especially this one), and Matthew is getting depressed at how many journalists have been taken in by the project, now in the hands of Colossal Biosciences (a “de-extinction” company), but most famously promoted by Harvard’s George Church, the founder of Colossal (curiously, Elon Musk had a hand in convincing Church to take this on). In fact, Matthew devotes a big section of his book As Gods: A Moral History of the Genetic Age, to debunking the Mammoth Project.

Now Scientific American, which I hoped would recover from its years of benighted wokeness, has taken up the story. (Click below to read, or find it archived here.)

How did the magazine do? (The author is journalist Adam Popescu and the editor is Andrea Thompson, “covering the environment, energy and earth sciences”.) Well, on first reading I’d give it a C. It does point out some problems to worry about after we produce a woolly mammoth, but is quite thin about whether they can get one in the first place.  For example, it doesn’t even note that an Asian elephant with a few genes that make it hairy and (perhaps) cold-tolerant is nothing like a Woolly Mammoth, separated by about 6.5 million years of evolution. (That’s about the time separating us from chimps and bonobos.) It is a hairy elephant with no behaviors that would help it survive on the tundra.  And they don’t even mention the problems of implanted a genetically altered elephant embryo back into a female Asiatic elephant. Here’s what I wrote in one post (the quote within is from the NYT):

Further, a lot of other genes differ between a mammoth and an Asian elephant. What guarantee is there that the inserted mammoth genes would be expressed correctly, or even work at all in concert with the Asian elephant developmental system?

But it gets worse. Since you can’t implant a transgenic embryo into an elephant mom (we don’t know how to do that, and we would get just one or two chances), Church had this bright idea:

Initially, Dr. Church envisioned implanting embryos into surrogate female elephants. But he eventually soured on the idea. Even if he could figure out in vitro fertilization for elephants — which no one has done before — building a herd would be impractical, since he would need so many surrogates.

Instead, Dr. Church decided to make an artificial mammoth uterus lined with uterine tissue grown from stem cells. “I’m not making a bold prediction this is going to be easy,” he said. “But everything up to this point has been relatively easy. Every tissue we’ve gone after, we’ve been able to get a recipe for.”

The idea has a few precedents. At the Children’s Hospital of Philadelphia, researchers have developed a sealed bag that can support a fetal lamb for four weeks, for example. But Colossal will need to build an artificial uterus big enough to house a fetus for around two years, reaching a weight of 200 pounds.

An artificial mammoth uterus? Seriously? If you think that’s gonna work, I have some land in Florida I’d like to sell you. Of course, if you’re going to breed these things, you’d have to make two of them of opposite sexes. Could they even do that?

That, in fact, is another huge problem beyond problem beyond the pretense that they are going to put a lot of mammoth-derived or mammoth-mimicking genes in an elephant and call it a Woolly Mammoth. An artificial womb for a baby elephant would be the size of a Volkswagen!  Scientific American doesn’t mention that problem, either.

Finally, the Colossal researchers apparently also inserted a gene thought to affect mouse lipid metabolism into the mouse (Nature, in the article below, doesn’t mention it), but the Sci. Am. article says in the second paragraph that the Woolly Mice have “cold adapted traits such as the way in which it sotres and burns fat”.  That is a lie. They don’t know whether the gene does that in the mice, and later on Sci. Am. gives the real story:

The team also targeted lipid metabolism, “which is the process by which the body breaks down, synthesizes and stores fats,” Shapiro says. The paper notes that “future experiments will examine the effect of high fat diets and temperature preferences” on the mice to inform further work toward the goal of developing cold-adapted elephant-mammoth hybrids.

So no, the mice are not cold adapted. (See below, too.)

The problems that Sci Am does mention involve mostly things about about the environment and conservation, perhaps prompted by the editor. And they are real problems, but won’t even need to be considered until we get one of these mammoths (the NBC Evening News on Tuesday said that Colossal envisions the Mammoth Release in 2028, which is pure bunk). Below are problems Sci. Am. lists, but they’re all problems that would arise if they created the faux mammoth and then put it into the wild. These are quotes:

But many experts in genetic engineering and conservation are skeptical. Rewilding is risky; species such as wolves and elephants have come into conflict with humans, and others have fallen victim to predators and poachers. No one knows what would happen if a mammoth—or, more technically, an elephant-mammoth hybrid—was released: What would it eat? How would we protect it? Could it reproduce?

. . . . As for saving the climate, “we’re looking at a warming world, and [Colossal’s researchers] want to bring back creatures that are adapted to the cold?” says Elsa Panciroli, a paleontologist at National Museums Scotland, who studies ancient mice-sized mammals. “I study animals from the past, and they should stay in the past. Lack of habitat, human conflict, agriculture, climate change—the idea that they can fix that with gene editing is missing the big picture.”

. . . “In certain ancient species’ DNA, you don’t know what the function of this DNA is, so there are more than ethical problems; there are biological hazards from moving and editing the DNA,” says Yale University geneticist Jiangbing. Zhou “I’m not sure about the potential risks of this type of work, as the function of ancient DNA in live mice may be difficult to predict.”

. . . What happens with the mice or—if the company ever realizes its ultimate ambition—the woolly mammoths is another ethical quandary. “I feel like Jeff Goldblum in Jurassic Park, but if we’re going to interfere with nature, there has to be good reason,” Panciroli says. Additionally, reintroduced animals (including elephants) are routinely targeted by poachers, points out Andrea Crosta, founder of a wildlife-crime-fighting nongovernment organization called Earth League International.

. . .“It’s arrogance,” says Sue Lieberman, vice president of international policy at the Wildlife Conservation Society, who spent decades fighting whaling and the ivory trade. “I’m not against technology. I’m not saying nature’s perfect. But this is such a waste of money when conservation is dying for lack of funds. To make some strange animal we can gawk at—we should be past that.”

Trailblazing biologist George Schaller agrees. “We need to protect what we have,” he says.

I think I’ll downgrade the grade I give to Sci. Am. to a D, for they completely omit the problems of making anything that resembles a Woolly Mammoth, and then point out problems that would arise if we could and then unleashed them on the tundra. They should have mentioned, as Nature implies below, that the whole project is simply bonkers and will not succeed. (If they do, I’ll eat my hat.) And Sci Am show pictures of hairy mice which are NOT the mice created by Colossal (see below).  Showing those photos borders on duplicity!

Nature, as you can tell by the headline below, does a much better job of pointing out the problems, though it doesn’t mention the Uterus Difficulty or the Behavior and Foraging Difficulty. I give the article an A-, though, because it does say that Colossal isn’t going to produce a woolly mammoth. Click to read:

They point out the main problem in the third through fifth paragraphs:

Colossal, which is based in Dallas, Texas, and is worth more than US$10 billion according to its latest valuation, says the woolly mouse represents an important step towards its goal of engineering Asian elephants — the mammoth’s closest living relative — with genetic changes for key mammoth traits. “The Colossal Woolly Mouse marks a watershed moment in our de-extinction mission,” said Ben Lamm, Colossal’s co-founder and chief executive, in the press release.

But some experts in mammoth genetics and genome editing question whether the mice represent a significant advance in either area, let alone a milestone on the way to bringing back woolly mammoths, which last roamed Earth some 4,000 years ago.

“It’s far away from making a mammoth or a ‘mammoth mouse’,” says Stephan Riesenberg, a genome engineer at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. “It’s just a mouse that has some special genes.”

And note that Colossal created some of their fuzzy mice by inserting into the mice genome not genes derived from mammoth sequences, but mouse mutations already known to make mice hairier. It’s a scam!

Shapiro [from Colossal] defends the decision to include mouse-specific mutations in Colossal’s woolly mice, in part because of the genetic chasm that separates mice and mammoths. “We have to choose modifications that are going to be compatible with healthy animals,” Shapiro says. “We’re not shoving mammoth genes into mice because there’s 200 million years of evolutionary distance between them.”

It’s not clear how many genetic changes would be needed to imbue elephants with mammoth traits. Lamm says Colossal’s goal isn’t to create an exact replica of mammoths, but a creature that can fill the ecological niches that mammoths occupied. “It’s really about rebuilding extinct species for today and looking for lost biodiversity and lost genes that drive those phenotypes.”

Making eight changes to an organism’s genome, as the Colossal team did, is now fairly standard in genetic engineering, Riesenberg says.

Riesenberg and his colleagues are developing methods to introduce dozens, or even hundreds, of Neanderthal-specific changes into human stem cells — to identify the biology that makes humans unique (“One cannot and should not recreate the Neanderthal,” he stresses). Altering an animal’s genome on this scale is one of the great frontiers in genome editing, Riesenberg adds. Even the capacity to make this many changes “would not bring you close to making a mammoth”.

Clearly Nature isn’t enthusiastic about this project, and they shouldn’t be. Even the woolly mice they show are not from their study (see below), but that took another scientist to point that out.

As Dr. Victoria Herridge points out below, they didn’t get the hairy mice shown in the journalism (and press-release) photos by combining the genes they said they inserted into the mouse. Instead, they appear to have inserted other genes already known to cause hairiness in mice, for because people have been breeding hairy “fancy mice” for years. The “mammothiest mouse” produced by Colossal is not the one shown in the pictures.

And so we have the BlueSky threads below from Dr. Victoria Herridge at the University of Sheffield, a paleontologist who studies real mammoths.  She simply takes the Colossal report apart, noting that the hairy mouse pictures used in Sci Am. do not show show the result of combined gene insertions used by the researchers, but some other mutations. Further, she notes that there’s no known effect of the “fat metabolism” genes on fat metabolism of the transgenic mice.  As Matthew adds, “note that the key experiment changing fat metabolism genes HAD NO EFFECT though they said little about that in the paper and the journalists all skipped over it…”

Here’s the hairiest mice that the Colossal people really produced by multiple insertions. They aren’t the ones in the picture above; they’re much more clean-cut! Note her comment on the inefficacy of the fat-metabolism gene.

 

Here Tori shows that Colossal should have used other mouse mutants to confect the mammoth story. Look at the double mutant Fgfr1/2!!!!

Finally, she tried to track down where the mice in all the magazines and the press release came from (the original BioRχiv paper is here).   These mice are in the supplementary materials in the article’s preprint, but involve fewer mutations than the ones touted as “mammothyt mice”:

I asked Matthew if he had ever seen any article in the popular press (beyond what’s in his book) that provided an accurate critical analysis of the Mammoth Project. He said, “no”.  As the warden said in the movie Cool Hand Luke, “What we have here is a failure to communicate.” Science journalism is, by and large, abysmal, though of course there are exceptions.

Finally, some humor from Dr. Cobb, who’s been beleaguered by science journalists about this for years, and always tells them that the project is dumb:

He’s dreaming of eating those damned woolly mice.

— Matthew Cobb (@matthewcobb.bsky.social) 2025-03-04T20:25:24.966Z

Skeptics love to bring up one particular topic regarding long-term human space exploration - radiation. So far, all of the research completed on it has been relatively limited and has shown nothing but harmful effects. Long-term exposure has been linked to an increase in cancer, cataracts, or even, in some extreme cases, acute radiation poisoning, an immediate life-threatening condition. NASA is aware of the problem and recently supported a new post-doc from MIT named Robert Hinshaw via the Institute for Advanced Concepts (NIAC) program. Dr. HHinshaw'sjob over the next year will be to study the effectiveness of an extreme type of mitochondria replacement therapy to treat the long- and short-term risks of radiation exposure in space.

Coots' nests in Amsterdam are built using discarded plastic, providing a time capsule into the material's use over the past few decades

We are running out of photos from different readers, but fortunately we have several remaining installments from Robert Lang‘s trip to Brazil’s Pantanal, one of which I’ll present today. But please send in your photos!

Robert’s captions and IDs are indented, and you can click on the photos to enlarge them.

Readers’ Wildlife Photos: The Pantanal, Part VIII: Birds

Continuing our mid-2025 journey to the Pantanal in Brazil, by far the largest category of observation and photography was birds: we saw over 100 different species of birds (and this was not even a birding-specific trip, though the outfitter also organizes those for the truly hard core). Here we continue working our way through the alphabetarium of common names.

Laughing falcon (Herpetotheres cachinnans):

Lesser yellow-headed vulture (Cathartes burrovianus). One of the several vultures we saw (which included the spectacular king vulture (Sarcoramphus papa), but alas, that one only at a great distance.):

Monk parakeet (Myiopsitta monachus):

Monk parakeets live in communal nests that they keep adding to, eventually resulting in gigantic snarls of branches with openings all over that are a constant hum of activity. Here’s a close-up of one, showing some of the individual nest openings within the apartment block:

Muscovy duck (Cairina moschata):

Nanday parakeet (Aratinga nenday):

And a pair of Nanday parakeets:

Orange-backed troupial (Icterus croconotus):

Peach-fronted parakeets (Eupsittula aurea). These tiny, wide-eyed birds look like play toys:

Plumbeous ibis (Theristicus caerulescens):

More birds to come.

Fernanda Pirie is Professor of the Anthropology of Law at the University of Oxford. She is the author of  The Anthropology of Law and has conducted fieldwork in the mountains of Ladakh and the grasslands of eastern Tibet. She earned a DPhil in Social Anthropology from Oxford in 2002, an MSc in Social Anthropology at University College London in 1998, and a BA in French and Philosophy from Oxford in 1986. She spent almost a decade practicing as a barrister at the London bar. Her most recent book is  The Rule of Laws: A 4,000-Year Quest to Order the World.

Skeptic: Why do we need laws? Can’t we all just get along?

Fernanda Pirie: That assumes we need laws to resolve our disputes. The fact is, there are plenty of societies that do perfectly well without formal laws, and that’s one of the questions I explore in my work: Who makes the law, and why? Not all sophisticated societies have created formal laws. For instance, the ancient Egyptians managed quite well without them. The Maya and the Aztec, as far as we can tell, had no formal laws. Plenty of much smaller communities and groups also functioned perfectly well without them. So, using law to address disputes is just one particular social approach. I don’t think it’s a matter of simply getting along; I do believe it’s inevitable that people will come into conflict, but there are many ways to resolve it. Law is just one of those methods.

It’s inevitable that people will come into conflict, but there are many ways to resolve it. Law is just one of those methods.

Skeptic: Let’s talk about power and law. Are laws written and then an authority is needed to enforce them, which creates hierarchy in society? Or does hierarchy develop for some other reason, and then law follows to deal with that particular structure?

FP: I wouldn’t say there’s always a single direction of development. In ancient India, for example, a hierarchy gradually developed over several thousand years during the first millennium BCE, with priests—eventually the Brahmins—and the king at the top. This evolved into the caste system we know today. The laws came later in that process. Legal texts, written by the Brahmins, outlined rules that everyone—including kings—had to follow.

Skeptic: So, the idea of writing laws down or literally chiseling them in stone is to create something tangible to refer to.. Not just, “Hey, don’t you remember, I said six months ago you shouldn’t do that?” Instead, it’s formalized, and everyone has a copy. We all know what it is, so you can hold people morally accountable for their actions.

FP: Exactly. That distinction makes a big difference. Every society has customs and norms; they often have elders or other sources of authority, who serve as experts in maintaining their traditions. But when it’s just a matter of, “This is what we’ve always done—don’t you remember?” some people can conveniently forget. Once something is written down, though, it gains authority. You can refer to the exact words, which opens up different possibilities for exercising power. “Look, these are the laws—everyone must know and follow them.” But it equally creates opportunities for holding people accountable.

Skeptic: So it’s a matter of “If you break the law, then these are the consequences.” It’s almost like a logic problem—if P, then Q. There’s an internal logic to it, a causal reasoning where B follows A, so we assume A causes B. Is something like that going on, cognitively?

Once something is written down, it gains authority. You can refer to the exact words, which opens up different possibilities for exercising power.

FP: Well, that cause-and-effect form is a feature of many legal systems, but not all of them. It’s very prominent in the Mesopotamian tradition, which influenced both Jewish law and Islamic law, and eventually Roman law—the legal systems that dominate the world today. It’s associated with the specification of rights—if someone does this, they are entitled to that kind of compensation, or this must follow from that. But the laws that developed in China and India were quite different. The Chinese had a more top-down, punitive system, focused on discipline and punishment. It was still an “if-then” system, but more about, “If you do this wrong, you shall be punished.” It was very centralized and controlling. In Hindu India, the laws were more about individual duty: this is what you ought to do to be a good Hindu. If you’re a king, you should resolve disputes in a particular way. The distinctions between these systems aren’t always sharp, but the casuistic form is indeed a particular feature of certain legal traditions.

Laws have never simply been rules. They’ve created intricate maps for civilization. Far from being purely concrete or mundane, laws have historically presented a social vision, promised justice, invoked a moral order ordained by God (or the Gods), or enshrined the principles of democracy and human rights. And while laws have often been instruments of power, they’ve just as often been the means of resisting it. Yet, the rule of law is neither universal nor inevitable. Some rulers have avoided submitting themselves to the constraints of law—Chinese emperors did so for 2,000 years. The rule of law has a long history, and we need to understand that history to appreciate what law is, what it does, and how it can rule our world for better or worse.

The rule of law is neither universal nor inevitable. Some rulers have avoided submitting themselves to the constraints of law.

Skeptic: In some ways it seems like we are seeking what the economist Thomas Sowell calls cosmic justice, where in the end everything is settled and everyone gets their just desserts. One purpose of the Christian afterlife is that all old scores are settled. God will judge everything and do so correctly. So, even if you think you got away with something, in the long run you didn’t. There’s an eye in the sky that sees all, and that adds an element of divine order to legal systems.

FP: Absolutely, and that characterizes many of the major legal systems, especially those associated with religion. Take the Hindu legal system—it’s deeply tied to a sense of cosmological order. Everyone must follow their Dharma, and the Brahmins set up the rules to help people follow their Dharma, so they can achieve a better rebirth. Similarly, Islamic Sharia law, which has had a poor reputation in recent times, is seen as following God’s path for the world, guiding people on how they should behave in accordance with a divine plan. Even the Chinese, who historically had a more top-down and punitive system, claimed that their emperors held the Mandate of Heaven—that’s why people had to obey them and their laws. They were at the top of the pyramid because of such divine authority.

Of course, there have also been laws that are much more pragmatic—rules that merchants follow to maintain their networks, or village regulations. Not all law is tied to a cosmic vision, but many of the most impressive and long-lasting legal systems have been.

Islamic Sharia law is seen as following God’s path for the world. Even the Chinese, who historically had a more top-down and punitive system, claimed that their emperors held the Mandate of Heaven.

Skeptic: The Arab–Israeli conflict can be seen as two people holding a deed to the same piece of land, each claiming, “The title company that guarantees my ownership is God and His Holy Book.” Unfortunately, God has written more than one Holy Book, leading both sides to claim divine ownership, with no cosmic court to settle the dispute.

FP: That’s been the case throughout history—overlapping legal and political jurisdictions. Many people today are worried about whether the nation-state, as we know it, is breaking down, especially with the rise of supranational laws and transnational legal systems. But it’s always been like this—there have always been overlaps between religious laws, political systems, and social norms. The Middle East is a perfect example, with different religious communities living side by side. It hasn’t always been easy, but over time, people have developed ways of coexisting. The current political battles in the Middle East are part of this ongoing tension.

Skeptic: In your writing, you offer this great example from the Code of Hammurabi, 1755–1750 BC. It is the longest, best-organized, best-preserved legal text from the ancient Near East, written in the Old Akkadian dialect of Babylonian, and inscribed on a stone stele discovered in 1901.

“These are the judicial decisions that Hammurabi, the King, has established to bring about truth and a just order in his land.” That’s the text you quoted. “Let any wronged man who has a lawsuit”—interesting how the word ‘lawsuit’ is still in use today—”come before my image as King of Justice and have what is written on my stele read to him so that he may understand my precious commands, and let my stele demonstrate his position so that he may understand his case and calm his heart. I am Hammurabi, King of Justice, to whom Shamash has granted the truth.”

Many people today are worried about whether the nation-state, as we know it, is breaking down.

Then you provide this specific example: “If a man cuts down a tree in another man’s date orchard without permission, he shall pay 30 shekels of silver. If a man has given a field to a gardener to plant as a date orchard, when the gardener has planted it, he shall cultivate it for four years, and in the fifth year, the owner and gardener shall divide the yield equally, with the owner choosing first.”

This sounds like a modern business contract, or today’s U.S. Uniform Commercial Code.

FP: Indeed, it’s about ensuring fairness among the farmers, who were the backbone of Babylon’s wealth at the time. I also find it fascinating that there are laws dealing with compensation if doctors kill or injure their patients. We often think of medical negligence as a modern issue, but it’s been around for 4,000 years.

Skeptic: But how did they determine the value of, say, a stray cow or cutting down the wrong tree? How did they arrive at the figure of 30 shekels?

FP: That’s a really interesting question. These laws were meant to last, and even in a relatively stable society, the value of money would have changed over time. People have studied this and asked how anyone could follow these laws for the hundreds of years that the stele stood and people referred to it. My view is that these laws were more exemplary—they probably reflected actual cases, decisions that judges were making at the time.

Laws have never simply been rules; they have created intricate maps for civilization, presented a social vision, promised justice, invoked a moral order, and enshrined principles of democracy and human rights.

Although Hammurabi wrote down his rules, he didn’t expect people to apply them exactly as written, as we do with modern legal codes. Instead, they gave a sense of the kind of compensation that would be appropriate for different wrongs or crimes—guidelines, not hard rules. Hammurabi likely collected decisions from various judicial systems and grafted them into a set of general laws, but they still retain the flavor of individual judgments.

Skeptic: Is there a sense of “an eye for an eye, a tooth for a tooth”—where the punishment fits the crime, more or less?

The Code of Hammurabi inscribed on a basalt slab on display at the Louvre, Paris. (Photo by Mbzt via Wikimedia)

FP: Absolutely. Hammurabi was trying to ensure that justice was done by laying out rules for appropriate responses to specific wrongs, ensuring fairness in compensation. But it’s crucial to understand that the famous phrase, “an eye for an eye, a tooth for a tooth,” which appears first in Hammurabi’s code and later in the laws of the Book of Exodus, wasn’t about enforcing revenge. Even though there’s a thousand-year gap between Hammurabi and the Bible, scholars believe this rule was about limiting revenge, not encouraging it. It meant that if someone sought revenge, it had to be proportional—an eye for an eye—but no more.

In other words, they wanted to prevent cycles of violence that arise from feuds. In a feuding society, someone steals a sheep, then someone retaliates by stealing a cow, and then someone tries to take an entire herd of sheep. The feud keeps getting bigger and bigger. So, the “eye for an eye” rule was a pragmatic approach in a society where feuding was common. It was meant to keep things under control.

Skeptic: From the ruler’s perspective, a feud is a net loss, regardless of who’s right or wrong.

FP: Feuding is a very common way of resolving disputes, especially among nomadic people. The idea, which makes a lot of sense, is that if you’re a nomadic pastoralist, your wealth is mobile—it’s your animals that have feet, which can be moved around. That also makes it easy to steal. If you’re a farmer, your wealth is tied to your land, so someone can’t run off with it. Since nomads are particularly vulnerable to theft, having a feuding system acts as a defense mechanism. It’s like saying, “If you steal my sheep, I’ll come and steal your cow.” You still see this in parts of the world, such as eastern Tibet, where I’ve done fieldwork. So, yes, kings and centralized rulers want to stop feuds because they represent a net loss. They want to put a lid on things and so establish a more centralized system of justice. This is exactly what Hammurabi was trying to do, and you see similar efforts in early Anglo- Saxon England, and all over the world.

Another interesting point is that every society has something to say about homicide. It’s so important that they have to lay out a response. However, I don’t think we should assume these laws were meant to stop people from killing each other. The fact is, we don’t refrain from murder because the law tells us not to. We don’t kill because we believe it’s wrong—except in the rare cases where morality has somehow become twisted and self-help justice occurs and people take the law into their own hands. The law, in this case, is more about what the social response should be once a killing has occurred. Should there be compensation? Punishment? What form should it take?

Every society needs some system to restore order and a sense of justice.

Skeptic: Is this why we need laws that are enforced regularly, fairly, justly, and consistently, so people don’t feel the need to take matters into their own hands?

FP: I’d put it a bit more broadly: we need systems of justice, which can include mediation systems. In a village in Ladakh—part of northern India with Tibetan populations where I did fieldwork—they didn’t have written laws, but they had very effective ways of resolving conflicts. They put a lot of pressure on the parties to calm down, shake hands, and settle the dispute. It’s vastly different from the nomads I worked with later in eastern Tibet, who had a very different approach. But both systems were extremely effective, and there was a strong moral sense that people shouldn’t fight or even get angry. It’s easy to look at these practices and say they’re not justice, especially when serious things like injuries, killings, or even rape are settled in this way. But for these villages, maintaining peace and order in the community was paramount, and it worked for them.

Every society needs some system to restore order and a sense of justice. What constitutes justice can vary greatly—sometimes it’s revenge, sometimes it’s about restoring order. Laws can be part of that system, and in complex societies, it becomes much harder to rely on bottom-up systems of mediation or conciliation. That’s where having written laws and judges becomes very useful.

Skeptic: In communities without laws or courts, do they just agree, “Tomorrow we’re going to meet at noon, and we’ll all sit down and talk this out?”

FP: Essentially, yes. In the communities I spent time with, it was the headman’s duty to call a village meeting, and everyone was expected to attend and help resolve the issue. In a small community like that, you absolutely could do it.

Skeptic: And if you don’t show up?

FP: There’s huge social pressure for people to play their part in village politics and contribute to village funds and activities.

Skeptic: And if they don’t, then what? Are they gossiped about, shunned, or shamed?

FP: Yes—all of those things, in various ways.

Skeptic: Let’s talk about religious laws. You mentioned Sharia, and from a Western perspective, it’s often seen as a disaster because it’s been hyped up and associated with terrorism. Can you explain how religious laws differ from secular laws?

FP: I’m wondering how much one can generalize here. I’m thinking of the religious laws of Hindu India, Islamic laws, Jewish laws, and I suppose Canon law in Europe—Christian law. I hesitate to generalize, though.

Skeptic: What often confounds modern minds are the very specific laws in Leviticus—like which food you can eat, which clothes you can wear, and how to deal with adultery, which would certainly seem to concern the affected spouse. But why should the state—or whatever governing laws or body—even care about such specific issues?

FP: This highlights a crucial point. In Jewish, Hindu, and Islamic law, the legal and moral spheres are part of the same domain. A lot of these laws are really about guiding people on how to live moral lives according to dharma, God’s will, or divine command. The distinction we often make between law and religion, or law and morality, doesn’t apply in those contexts. The laws are about instructing people on how to live properly, which can involve family relations, contracts, land ownership, but also prayer and ritual.

As for the laws in Leviticus, they’ve puzzled people for a long time. They seem to be about purity and how Jews should live as good people, following rules of cleanliness, which partly distinguished them from other tribes.

Skeptic: What exactly is Sharia law?

FP: Sharia literally means “God’s path for the world.” It’s not best translated as “law” in the way we understand it. It’s more about following the path that God has laid out for us, a path we can’t fully comprehend but must do our best to interpret. The Quran is a guide, but it doesn’t lay out in detail everything we should do. The early Islamic scholars—who were very important in its formative days—studied the Quran and the Hadith (which tradition maintains records the Prophet’s words and actions) to work out just how Muslims should live according to God’s command. They developed texts called fiqh, which are what we might call legal texts, going into more detail about land ownership, commercial activities, legal disputes, inheritance, and charitable trusts.

Islamic law has very little to say about crime.

Islamic law has very little to say about crime. That’s one misconception. People tend to think it’s all about harsh punishments, but the Quran mentions crime only briefly. That was largely the business of the caliphs—the rulers—who were responsible for maintaining law and order. Sharia is much more concerned with ritual and morality, and with civil matters like inheritance and charitable trusts.

Skeptic: Much of biblical legal and moral codes have changed over time. Christianity went through the Enlightenment. But Islam didn’t seem to go through a similar process. Is that a fair characterization?

FP: I’d say that’s partly right. But I’ve never thought about it in exactly those terms. In any legal tradition, there’s resistance to change—that’s kind of the point of law. It’s objective and fixed, so any change requires deep thought. In the Islamic world, there’s been a particularly strong sense that it’s not for people to change or reinterpret God’s path. The law was seen as something fixed.

But in practice, legal scholars, called muftis, were constantly adapting and changing legal practices to suit different contexts and environments. That’s one of the real issues today—Islamic law has become a symbol of resistance to the West, appealing to fundamentalism by going “back to the beginning.”

Skeptic: Let’s talk about stateless law of tribes, villages, networks, and gangs. For example, we tend to think of pirates as lawless, chaotic psychopaths who just randomly raided commerce and people. But, in fact, they were pretty orderly. They had their own constitutions. Each ship had a contract that everyone had to sign, outlining the rules. There’s even this interesting analysis of the Jolly Roger (skull and crossbones) flag. Why fly that flag and alert another ship that you’re coming? In his book The Invisible Hook: The Hidden Economics of Pirates, the economist Peter Leeson argued that it is a signal: “We’re dangerous pirates, and we’re coming to take your stuff, so you might as well hand it over to us, and we won’t kill you.” It’s better for the pirates because they can get the loot without the violence, and it’s better for the victims because they get to keep their lives. Occasionally, you do have to be brutal and make sure your reputation as a badass pirate gets a lot of publicity, so people know that when they see the flag, they should just surrender. But overall, it was a pretty orderly system.

FP: Yes, but it’s only kind of organized. That’s the point. For example, in The Godfather Don Corleone was essentially making up his own rules, using his power to tell others what he wanted. That’s the nature of the Mafia—yes, they had omertà (the rule of silence) and rules about treating each other’s wives with respect, but these rules were never written down. Alleged members who went on trial even denied—under oath—that any kind of organization or rules existed. This was particularly true with the Sicilian Mafia. The denial served two purposes: first, it protected them from outside scrutiny, and second, it allowed powerful figures like Don Corleone—or the real-life Sicilian bosses—to bend the rules whenever they saw fit. If the rules aren’t written down, it’s harder to hold them accountable. They can simply break the rules and impose their will.

Skeptic: Let’s discuss international law. In 1977, David Irving published Hitler’s War, in which he claimed that Hitler didn’t really know about the Holocaust. Rather, Irving blamed it on Himmler specifically, and other high-ranking Nazis in general, along with their obedient underlings. Irving even offered $1,000 to anyone who could produce an order from Hitler saying, “I, Adolf Hitler, hereby order the extermination of European Jewry.” Of course, no such order exists. This is an example of how you shift away from a legal system. The Nazis tried to justify what they were doing with law, but at some point, you can’t write down, “We’re going to kill all the Jews.” That can’t be a formal law.

FP: Exactly. Nazi Germany had a complex legal case, and I’m not an expert on it, but you can see at least a couple legal domains at play. First, they were concerned with international law, especially in how they conducted warfare in the Soviet Union. They at least tried to make a show of following international laws of war. Second, operationally, they created countless laws to keep Germany and the war effort functioning. They used law instrumentally. But when they felt morally uncomfortable with what they were doing, the obvious move was to avoid writing anything down. If it wasn’t documented, it wasn’t visible, and so it became much harder to hold anyone accountable.

Nazi Germany had a complex legal case. Operationally, they created countless laws to keep Germany and the war effort functioning. They used law instrumentally.

Skeptic: During the Nuremberg trials, the defense’s argument was often, “Well, we lost, but if we had won, this would have been legal.” So they claimed it wasn’t fair to hold these trials since they violated the well-established principle of ex post facto, because there was no international law at the time. National sovereignty and self-determination was the norm, so they were saying, in terms of the law of nations, “We were just doing what we do, and it’s none of your business.”

View from above of the judges' bench at the International Military Tribunal in Nuremberg. (Source: National Archives and Records Administration, College Park.)

FP: Legally speaking, the Nuremberg trials were both innovative and hugely problematic. The court assumed the power to sit in judgment on what the leaders of independent nation-states were doing within their borders, or at least largely within their borders (the six largest Nazi death camps were in conquered Poland). But it was revolutionary in terms of developing the concepts of genocide, crimes against humanity, and the reach of international law with a humanitarian focus. So yes, it was innovative and legally difficult to justify, but I don’t think anyone involved felt there was any question that what they were doing was the right thing.

Skeptic: It also established the legal precedent that, going forward, any dictator who commits these kinds of atrocities—if captured—would be held accountable.

FP: Exactly. And that eventually led to the movement that set up the International Criminal Court, where Slobodan Milošević was prosecuted, along with other leaders. Although, it’s extremely difficult to bring such people to trial, and ultimately, the process can be more symbolic than practical.

Is the existence of the International Criminal Court really going to stop someone from committing mass atrocities? I doubt it. But it does symbolize to the world that genocide and other heinous crimes will be called out, and people must be held accountable. In a way, it represents the wider moral world we want to live in and the standards we expect nations to uphold.

Skeptic: Skeptic once asked Elon Musk: “When you start the first Mars colony, what documents would you recommend using to establish a governing system? The U.S. Constitution, the Bill of Rights, the Universal Declaration of Human Rights, the Humanist Manifesto, Atlas Shrugged, or Against the State, an anarcho-capitalist manifesto?” He responded with, “Direct democracy by the people. Laws must be short, as there is trickery in length. Automatic expiration of rules to prevent death by bureaucracy. Any rule can be removed by 40 percent of the people to overcome inertia. Freedom.”

FP: What a great, specific response! He’s really thought about this. Those are some interesting ideas, and I agree that there’s a lot to be said for direct democracy. The main problem with direct democracy, however, is that when you have too many people it becomes cumbersome. How do you gather everyone in a sensible way? The Athenians and Romans had huge assemblies, which created a sense of equality, and that’s valuable. Another thing I would do, which I’ve discussed with a colleague of mine, Al Pashar, is to rotate positions of power. She did research in Indian villages, and I’ve done work with Tibetans in Ladakh, and we found they had similar systems where every household provided a headman or headwoman in turn.

Rotating power is effective at preventing individuals from concentrating too much power.

You might think rotating leadership wouldn’t work, because some people aren’t good leaders, while others are. Wouldn’t it be better to elect the best person for the job? But we found that rotating power is effective at preventing individuals from concentrating too much power. Yes, it’s good to have competent leaders, but when their family or descendants form an elite, you get a hierarchy and bureaucracy. Rotating power prevents that. That’s what I would do in terms of a political system.

As for laws, I’m less concerned with their length, as long as they are accessible and visible for everyone to read and reference. What’s important is having essential laws clearly posted for all to see. And there should be a good system for resolving disputes—perhaps mediation and conciliation rather than a lot of complex laws, with just a few laws in the background.

Skeptic: We’ll send this to Elon, and maybe he’ll hire you to join his team of social engineers.

FP: Although I’m not sure I want to go to Mars, I’d be happy to advise from the comfort of Oxford!

The Moon's getting to be a popular place. Firefly's Blue Ghost touched down on March 2nd in Mare Crisium. It's the first privately built lander to land safely and begin its mission. The little spacecraft set down safely in an upright, stable position and sent back an "I'm here" signal right away.

So far, in the context of 1920s quantum physics, I’ve given you a sense for what an ultra-microscopic measurement consists of, and how one can make a permanent record of it. [Modern (post-1950s) quantum field theory has a somewhat different picture; please keep that in mind. We’ll get to it later.] Along the way I’ve kept the object being measured very simple: just an incoming projectile with a fairly definite motion and moderately definite position, moving steadily in one direction. But now it’s time to consider objects in more interesting quantum situations, and what it means to measure them.

The question for today is: what is a quantum superposition?

I will show you that a quantum superposition of two possibilities, in which the wave function of a system contains one possibility AND another at the same time, does not mean that both possibilities occur; it means that one OR the other may occur.

Instead of a projectile that has a near definite motion, as we’ve considered in recent posts, let’s consider a projectile that is in a quantum superposition of two possible near-definite motions:

• maybe it is moving to the left at a near-definite speed, or
• maybe it is moving to the right at a similar near-definite speed.

This motion is along the x-axis, the coordinate of a one-dimensional physical space. If the projectile is isolated from the rest of the world, we can write a wave function for it alone, which might initially look like

Fig. 1: The wave function of the projectile at the initial time, with two peaks about to head in opposite directions; see Fig. 2.

in which case its evolution over time will look like this:

Fig. 2: The evolution of the isolated projectile’s wave function.

Again I emphasize this is not the wave function of two particles, despite what you might intuitively guess. This is the wave function of a single particle in a superposition of two possible behaviors. For a similar example that we’ll return to in a few weeks, see this post.

Because the height and speed of the two peaks is the same, there is a left-to-right symmetry between them. We can therefore conclude, before we even start, that there’s a 50-50 chance of the particle going right versus going left. More generally, whatever we observe to the left (x<0) will happen with the same probability as what we observe to the right (x>0).

Today I will show you that even though the wave function has one peak moving to the left AND one peak moving to the right, nevertheless this wave function does not describe a projectile that is moving to the left AND moving to the right. Instead, it means that the projectile is moving to the left OR moving to the right. Superposition is an OR, not an AND. In other words, in pre-quantum language, we have either

Fig. 4: The pre-quantum view of the wave function in Figs. 1 and 2; either possibility may occur.

We never have both.

But don’t take my word for it. Let’s see how quantum physics actually works.

First Measurement: A Ball to the Left

Our first goal: to detect the projectile if it is moving to the left.

Let’s start by doing almost the same thing we did in this post, which you may want to read first in order to understand the pictures and the strategy that I’ll present below. To do this, we’ll put a measurement ball on the left, which the projectile will strike if it is moving to the left.

Since we now have a system of two objects rather than one, the space of possibilities for the system now has to be two-dimensional, to include both the position x1 of the projectile and the position x2 of the ball. This now requires us to consider a wave function for not just the projectile alone, as we did in Figs. 1 and 2, but for the projectile and the ball together. This wave function will give us probabilities for each possible arrangement of the projectile and ball — for each choice of x1 and x2.

We’ll put the ball at x2 = -1 initially — to the left of the projectile initially — so that the initial wave function looks like Fig. 4, which shows its absolute value squared as a function of x1 and x2.

Figure 4: The absolute square of the wave function for the projectile (with position x1 near zero) in a superposition of states as in Fig. 1, and the ball which stands ready at position x2=-1 (to the projectile’s left in physical space.)

This wave function has the same shape in x1 as the wave function in Fig. 1, but now centered on the line x2=-1. A collision between projectile and ball will become likely when a peak of the wave function approaches the point x1=x2=-1.

As usual, let’s try to think about this in a pre-quantum language first. If I’m right about wave functions, we have two options:

• The projectile is heading to the left and the measurement ball will react OR
• The projectile is heading to the right and the measurement ball will not react.

Since our wave function is left-to-right symmetric, each option is equally likely, and so if we do this experiment repeatedly, we should see the ball react about half the time.

Here are the two pre-quantum options shown in the usual way, with

• a picture in physical space on the left, and
• a picture of the same event in the space of possibilities on the right.

In the first possibility (Fig. 5a), the projectile moves left, strikes the ball, and the ball recoils to the left. As the ball moves to the left in physical space, the system moves down (toward more negative x2) in the space of possibilities.

Figure 5a: As viewed from physical space (left) and the space of possibilities (right), the projectile moves left and strikes the ball, after which the ball moves left. The ball thus measures the leftward motion of the projectile. The dashed orange line indicates where a collision can occur.

OR

Figure 5a: As viewed from physical space (left) and the space of possibilities (right), the projectile moves right, leaving the ball unscathed. The ball thus measures the rightward motion of the projectile. The dashed orange line indicates where a collision can occur.

In the second possibility (Fig. 5b), the projectile moves right and the ball remains unscathed; in this case, viewed in the space of possibilities, x2 remains at -1 during the entire process while x1 changes steadily toward more positive values.

What about in quantum physics? The wave function should include both options in Figs. 5a and 5b.

Here is an actual solution to the Schrödinger wave equation, showing that this is exactly what happens (and it has more details than the sketches I’ve been doing in my measurement posts, such as this one or this one.) The two peaks spread out more quickly than in my sketches (and I have consequently adjusted the vertical axis as time goes on so that the two bumps remain easily visible.) But the basic prediction is correct: there are indeed two peaks, one moving like the pre-quantum system in Fig 5a, changing direction and moving toward more negative x2, and the other moving like the pre-quantum system in Fig. 5b, moving steadily toward more positive x1.

Figure 6: Actual solution to Schrödinger’s wave equation, showing the absolute square of the wave function beginning with Fig. 4. Notice how the right-moving peak travels steadily toward more positive x1, as in Fig. 5b, while the left-moving peak shows signs of the collision and the subsequent motion of the system toward more negative x2, as in Fig. 5a.

Importantly, even though the system’s wave function displays both possibilities to us at the same time, there is no sense in which the system itself can be in both possibilities at the same time. The system has a near-50% probability of being observed to be within the first peak, near-50% probability of being observed to be within the second, and exactly 0% probability of being observed within both.

Second Measurement: A Ball to the Right

Now let’s put a ball to the right instead, at x=+1. This is a different ball from the previous (we’ll use both of them in a moment) so I’ll color it differently and call its position x3. The pre-quantum behaviors are the same as before, but with x2 replaced with x3 and with the collision happening at positive values of x1 and x3 instead of negative values of x1 and x2.

Figure 7a: As in Figure 5a, but with the orientation reversed.

OR

Figure 7b: As in Figure 5b, but with the orientation reversed.

The quantum version is just a 180-degree rotation of Fig. 6 with x2 replaced with x3.

Figure 8: The evolution of the absolute-value squared of the wave function in this case; compare to Fig. 6 and to Figs. 7a and 7b. Third Measurement: A Ball on Both Sides

But what happens if we put a ball on the left and a ball on the right? Initially the balls are at x2=-1 and x3=+1. What happens later?

Now there are four logical possibilities for what might happen:

1. The ball on the left responds while the ball on the right does not
2. The ball on the right responds while the ball on the left does not
3. Neither ball responds
4. Both balls respond

Where in the space of possibilities do these four options lie? The four logical possibilities listed above would put the ball’s positions in these four possible places:

• Option 1: x2 < -1 and x3 = +1 (and x1 negative, as in Fig. 5a)
• Option 2: x2 = -1 and x3 > +1 (and x1 positive, as in Fig. 7a)
• Option 3: x2 = -1 and x3 = +1 (and x1 is ???)
• Option 4: x2 < -1 and x3 > +1 (and x1 is ???)

The fact that it is not obvious where to put x1 in the last two options should already make you suscpicious; but just setting their x1 to zero for now, let’s draw where these four options occur in the space of possibilities. In Fig. 9 I’ve drawn the lines x2=-1 and x3=+1 across the box, with option 3 at their crossing point. Option 1 lies below down and to the left of option 3; option 2 is found to the rigt of option 3; and option 4 is found down and to the right.

Figure 9: Where the four options are located, roughly speaking. The lines cross at the location x2=-1, x3=+1. If I’m right, only the two cases where one ball moves will have any substantial probability.

What does the wave function actually do? Can the simple two-humped superposition at the start, analogous to Fig. 4, end up four-humped?

Not in this case, anyway. Fig. 10, which depicts the peaks of the absoulte-value-squared of the wave function only, shows the output of the Schrödinger equation. Compare the result to Fig. 9; there are peaks only for options 1 and 2, in which one ball moves and the other does not.

Figure 10: A plot showing where the absolute-value squared of the wave function is largest as the wave function evolves. The axes are as in Fig. 9. Initially the two peaks move in opposite directions parallel to the x1 axis; then, after the projectile collides with one ball or the other, one peak moves down (to more negative x2) and the other to the right (more positive x3). These correspond to the expected options when one and only one ball moves; see Fig. 9.

With balls on either side of it, the projectile cannot avoid hitting one of them, whether it goes right or left, which rules out option 3. And the wave function does not put a peak at option 4, showing there’s no way the projectile can cause both balls to move. The two peaks in the wave function move only in the x1 direction as the projectile goes left OR right; then the projectile collides with one ball OR the other; then the ball with which it collided moves, meaning that the system moves to more negative x2 (i.e. down in Fig. 10) OR to more positive x3 (i.e. to the right in Fig. 10), just as expected from Fig. 9.

Actually it’s not difficult to get the third option — but we don’t need quantum physics for that!

We simply change the original wave function to contain three possibilities: the projectile moves left, or it moves right, or it doesn’t move at all. If it doesn’t move at all, then neither ball will react, a third option even in pre-quantum physics:

If the projectile were isolated, we would encode this notion in a wave function which looks like this:

and when we include the two balls we would see the wave function with three peaks, one sitting still at the point marked “Neither Ball Moves” in Fig. 9. But this isn’t particularly exciting or surprising, since it’s intuitively obvious that a stationary projectile won’t hit either ball.

Every Which Way

There simply is no wave function you can choose — no initial superposition for the single projectile — which can cause the projectile to collide with both balls. The equations will never let this happen, no matter what initial wave function you feed into them. It’s impossible… because a superposition is an OR, not an AND. There is no way to make the projectile go left AND right — not if it’s a particle in 1920s quantum physics, anyway.

Yes, the wave function itself can have peaks that appear at to be in several places at the same time within the space of possibilities, as in Figs. 6, 8, and 10. But the wave function is not the physical system. The wave function tells us about the probabilities for the system’s possibilities; its peaks are just indicating what the most likely possibilities are.

The system itself can only realize one of the many possibilities — it can only be found (through a later measurement) in one place within the space of possibilities. This is always true, even though the wave function for the system highlights all the most probable possibilities simultaneously.

A particle, in the strict sense of the term, is an object with a position and a momentum, even though we cannot know both perfectly at any moment, thanks to Heisenberg’s uncertainty principle. It can only be measured to be in one place, or can only be measured to be traveling in one direction, at a time. In 1920s quantum physics, these statements apply to an electron, which is viewed as a strict particle, and so it cannot go in two directions at once, nor can it be in two places at once. The fact that we are always somewhat ignorant of where an electron is and/or where it is going, and the fact that quantum physics puts ultimate limitations on our ability to know both simultaneously, do not change these basic conceptual lessons… the lessons of (and for) the 1920s.

In 2006 (yes, it was that long ago – yikes) the International Astronomical Union (IAU) officially adopted the definition of dwarf planet – they are large enough for their gravity to pull themselves into a sphere, they orbit the sun and not another larger body, but they don’t gravitationally dominate their orbit. That last criterion is what separates planets (which do dominate their orbit) from dwarf planets. Famously, this causes Pluto to be “downgraded” from a planet to a dwarf planet. Four other objects also met criteria for dwarf planet – Ceres in the asteroid belt, and three Kuiper belt objects, Makemake, Haumea, and Eris.

The new designation of dwarf planet came soon after the discovery of Sedna, a trans-Neptunian object that could meet the old definition of planet. It was, in fact, often reported at the time as the discovery of a 10th planet. But astronomers feared that there were dozens or even hundreds of similar trans-Neptunian objects, and they thought it was messy to have so many planets in our solar system. That is why they came up with the whole idea of dwarf planets. Pluto was just caught in the crossfire – in order to keep Sedna and its ilk from being planets, Pluto had to be demoted as well. As a sort-of consolation, dwarf planets that were also trans-Neptunian objects were named “plutoids”. All dwarf planets are plutoids, except Ceres, which is in the asteroid belt between Mars and Jupiter.

So here we are, two decades later, and I can’t help wondering – where are all the dwarf planets? Where are all the trans-Neptunian objects that astronomers feared would have to be classified as planets that the dwarf planet category was specifically created for? I really thought that by now we would have a dozen or more official dwarf planets. What’s happening? As far as I can tell there are two reasons we are still stuck with only the original five dwarf planets.

One is simply that (even after two decades) candidate dwarf planets have not yet been confirmed with adequate observations. We need to determine their orbit, their shape, and (related to their shape) their size. Sedna is still considered a “candidate” dwarf planet, although most astronomers believe it is an actual dwarf planet and will eventually be confirmed. Until then it is officially considered a trans-Neptunian object. There is also Gonggong, Quaoar, and Orcus which are high probability candidates, and a borderline candidate, Salacia. So there are at least nine, and possibly ten, known likely dwarf planets, but only the original five are confirmed. I guess it is harder to observe these objects than I assumed.

But I have also come across a second reason we have not expanded the official list of dwarf planets. Apparently there is another criterion for plutoids (dwarf planets that are also trans-Neptunian objects) – they have to have an absolute magnitude less than +1 (the smaller the magnitude the brighter the object). Absolute magnitude means how bright an object actually is, not it’s apparent brightness as viewed from the Earth. Absolute magnitude for planets is essentially the result of two factors – size and albedo. For stars, absolute magnitude is the brightness as observed from 10 parsecs away. For solar system bodies, the absolute magnitude is the brightness if the object were one AU from the sun and the observer.

What this means is that astronomers have to determine the absolute magnitude of a trans-Neptunian object before they can officially declare it a dwarf planet. This also means that trans-Neptunian objects that are made of dark material, even if they are large and spherical, may also fail the dwarf planet criteria. Some astronomers are already proposing that this absolute magnitude criterion be replaced by a size criterion – something like 200 km in diameter.

It seems like the dwarf planet designation needs to be revisited. Currently, the James Webb Space Telescope is being used to observe trans-Neptunian objects. Hopefully this means we will have some confirmations soon. Poor Sedna, whose discovery in 2003 set off the whole dwarf planet thing, still has not yet been confirmed.

The post Where Are All the Dwarf Planets? first appeared on NeuroLogica Blog.

In a record-breaking test, researchers remotely detected radioactive material by shooting it with infrared laser pulses and analysing how the light scattered

A supermassive black hole that doesn't appear to be where we would expect seems to be travelling at more than a thousand kilometres per second – the result of a giant cosmic collision

It is impossible for us to know exactly how another person's experience of the world compares to our own, but a new experiment is helping to reveal that colour is indeed a shared phenomenon