Isegoria

Brandon Weigel talks about the potential for supplying Mars with an artificial magnetic field:

By placing a satellite equipped with technology to produce a powerful magnetic field at Mars L1 (a far orbit around Mars where gravity from the Sun balances gravity from Mars, so that the satellite always remains between Mars and the Sun), we could encompass Mars in the resulting magnetic sheath.

Earth’s magnetic field, originating at it’s core, has a strength of ~6*10^-5 Teslas at the distance of the Earth’s surface. This is the force which deflects compass needles. It is also the strength required to defend our atmosphere against deadly solar wind. However, a space-based magnetic field at Mars does not have to be quite this powerful. First of all, our goal is only to encompass Mars in the magnetosheath of the field; it does not need to extend as far as the Earth’s does. Earth’s magnetosheath extends to ~6 million kilometers. Mars L1 is only about 1 million km from Mars. Of course, we are going to want to allow some leeway for potential solar flare events, but extending the field ~1.5 million km is probably sufficient.

Another thing to take into account is the fact that the intensity of solar wind at Mars’ distance is less than half that at 1 AU. This means that we only need a magnetic field half as powerful as what we would have needed to defend a planet at Earth’s distance from the sun. Taking both of these factors into account, a space-based magnetic field around Mars only needs to have a strength of roughly 11% that of Earth’s. This will create a magnetosheath long enough to extend 500,000 kilometers beyond Mars.

Using the magnetic field magnitude equation, we can now solve for the amperage of the “wire” required to produce such a field. This yields a current of ~200 Mega-amperes. Any electrician knows right now that we are going to need a BIG ASS wire.

[...]

Some things to note are the exceptionally low voltage for the system of about 2 volts, and the dimensions/mass of the copper solenoid which come out to a torus with a total diameter of ~3.5 meters and a mass of ~57 tonnes. This is a big copper doughnut. It would fill the average living room area wall-to-wall and weigh more than 6x the legal mass of a loaded semi truck on the freeway. A magnetic field of ~81 Teslas is generated at the surface of the solenoid; nearly twice the strength of the strongest artificial continuous magnetic field ever produced to date. Another thing to note is the fact that a fission reactor of this size will require over 40 tonnes of uranium every two years to remain in operation. This may be the biggest problem for any future Martian-magnetosphere endeavor, seeing as a launch to Mars from Earth takes about 18 months and the abundance of uranium on Mars itself is unknown.

Scientists have identified a new kind of human brain cell:

The research team, co-led by Lein and Gábor Tamás, Ph.D., a neuroscientist at the University of Szeged in Szeged, Hungary, has uncovered a new type of human brain cell that has never been seen in mice and other well-studied laboratory animals.

Tamás and University of Szeged doctoral student Eszter Boldog dubbed these new cells “rosehip neurons” — to them, the dense bundle each brain cell’s axon forms around the cell’s center looks just like a rose after it has shed its petals, he said. The newly discovered cells belong to a class of neurons known as inhibitory neurons, which put the brakes on the activity of other neurons in the brain.

The study hasn’t proven that this special brain cell is unique to humans. But the fact that the special neuron doesn’t exist in rodents is intriguing, adding these cells to a very short list of specialized neurons that may exist only in humans or only in primate brains.

The researchers don’t yet understand what these cells might be doing in the human brain, but their absence in the mouse points to how difficult it is to model human brain diseases in laboratory animals, Tamás said. One of his laboratory team’s immediate next steps is to look for rosehip neurons in postmortem brain samples from people with neuropsychiatric disorders to see if these specialized cells might be altered in human disease.

The whole argument over how much carbon dioxide is on Mars now is totally irrelevant, since we need to import far, far more nitrogen to terraform the planet:

The surface pressure on Mars now averages about 0.6 percent of our own sea level pressure, or about 0.087 psi (600 pascals), and is thus a “physiological vacuum”. This means the pressure is less than a tenth of the “Armstrong Limit” of about 0.9 psi (6,200 pascals) where blood boils and far below what is needed to survive even with pure oxygen. You would need to wear a pressure suit to survive on the surface, just like on the Moon. Fortunately, though chilly, the temperatures on Mars are much milder than those on the Moon.

In addition, the surface of Mars is exposed to about 250 millisieverts (mSv) per Earth year of solar and galactic (cosmic) radiation, composed partly of dangerous high-speed atomic nuclei that can leave a trail of dead brain cells behind. Due to these particles, cosmic radiation is more dangerous than “regular” radiation. Crews and early civilian settlers would need to live underground in heavily shielded, pressurized habitat buildings to prevent the cosmic ray nuclei from reaching them. For reference, you would experience some radiation sickness if you got a dose of 1000 mSv all at once. In interplanetary space, you would get about 657 mSv per year without shielding, but on Mars, the planet itself blocks half of the radiation and the thin atmosphere absorbs another 20 percent of what remains. At this lower but constant rate, you would not get sick but there would be cumulative cell damage and a slow increase in cancer risk. On Earth, at sea level, we have in effect a layer of air equivalent in mass to 10.3 meters of water over our heads, which absorbs virtually all of the dangerous high-energy particles. On Mars, that layer is equivalent to about 20 centimeters of water, barely enough to shield anyone from a dangerous solar “proton storm” radiation outburst.

So there are three main reasons we need significant air pressure on Mars: to remove the need for pressure suits when working outside (and so that we would no longer need to live in pressurized habitats), to allow water to exist as a liquid on the surface, and to block the ubiquitous cosmic radiation so that buildings can be right on the surface and so that people can work on the surface without being irradiated. We can look at this issue from two points of view: radiation blocking mass and air pressure. So how much air mass and pressure do we really need?

From the radiation perspective, this is primarily a matter of sheer mass. On Earth at sea level, we have enough air over our heads so that only a tiny fraction of the natural background radiation most people get per year, totaling 3 to 6 mSv, is from space. To duplicate that very good level of protection on Mars requires a comparable amount of air mass (10.3 metric tons) over every square meter of Mars surface, ignoring the great altitude differences. Multiply this by the number of square meters of Mars surface and you get the required air mass: 1.493 trillion metric tons. This amount would create about 6.14 psi of air pressure or about 0.42 of Earth sea level pressure. More importantly, essentially all of the dangerous cosmic radiation from space would be blocked. This compares to the paltry 25 trillion metric tons of air currently in place at Mars, almost all of it CO2.

Some may note that for the same air column mass (the mass of air over a given surface area), we are not getting as much air pressure as we do on Earth. With Mars lower gravity, about 38% of Earths, it takes more air mass per square meter than it does on Earth to produce the same amount of pressure. So with the radiation threat now (theoretically) dealt with, how much air pressure do we need and what kind?

Right now, the air you are breathing is about 78 percent nitrogen and only about 21 percent oxygen. Carbon dioxide is a trace gas, at only 0.04 percent. You actually breathe 25 times more argon than carbon dioxide. If you are old enough, or are a space history buff, you may remember the Apollo 1 fire. The first Apollo spacecraft being prepared to be launched with a crew had about 16 psi of pure oxygen inside it during a pre-launch test, and all of the metal and plastic surfaces were saturated with oxygen. The capsule interior was like a fire bomb waiting for one tiny spark. The three astronauts were quickly asphyxiated by smoke within a minute of that spark and most of the interior of the capsule was incinerated. This horrific accident illustrates how dangerous high levels of oxygen are.

So future colonists would have little use for an atmosphere of almost all carbon dioxide, and they would not want an atmosphere mostly of oxygen due to the huge fire risk it would create. It turns out that the oxygen in any future nitrogen-oxygen atmosphere should be less than 50 percent of the total air pressure, but with the 42 percent pressure described above, we would still need a future 50-50 oxygen and nitrogen mix. (The amount of nitrogen delivered should be related to the future oxygen component.) So if we increase the air column mass to about 12.3 metric tons over each meter of surface, we get almost exactly half sea level pressure, or about 7.35 psi. To create this half-atmosphere of pressure (almost all of nitrogen) we need to add 1,784 trillion tons of nitrogen. However, this is equivalent to an altitude on Earth of about 5,200 meters, the altitude of the highest community on Earth in the Andes.

We assume, once we have a half-atmosphere of pressure, early settlers would be using oxygen helmets when working outside, and living inside slightly pressurized habitats, which could then be on the surface, with a nitrogen-oxygen mix. In addition, those in charge of the terraforming process would want to find ways to slowly add oxygen to the atmosphere, such as using the oxygen in some of the carbon dioxide and the existing water on Mars. This may take a long time, but adding oxygen will also add to the atmospheric pressure. Eventually, perhaps after centuries, there would be enough oxygen to breath and green plants could grow outside, but not so much as to be dangerous. A reasonable mix at about 10 psi would obviously be 70 percent nitrogen and 30 oxygen oxygen, providing the needed 3 psi of oxygen. This would be similar to being at about 3,000 meters on Earth, which the majority of people can obviously tolerate. For example, the town of Leadville, Colorado, is at an altitude of 3,100 meters. This is why we want the nitrogen in place first as it is a non-reactive gas.

Wait, I have a question:

Now, of course, many people will wonder where do we get all of these trillions of tons of nitrogen to import onto Mars. The planet has very little of it: just a few percent of what is needed, as most of it was lost during the last 3.5 billion years. However, It turns out that the outer solar system has huge amounts of nitrogen, both as a gas, such as on Titan, and as a semi-solid slush or ice on Pluto, Triton, and very probably the other large Kuiper Belt dwarf planets. Small asteroids would not have significant amounts of nitrogen as their gravity would have been too low to hold an atmosphere. We should be able to mine some of this nitrogen and move it to Mars where it can help support life. The current atmospheric loss rate from Mars would be very low.

Right now, it is true we have no means of moving the nitrogen, but chances are, with the new private investments in fusion power, that we will have it before we are ready to start terraforming. Fusion rocket powered tugs would only need to thrust for a few days to a couple weeks to send huge loads of nitrogen—as much as 100 million tons in each load—into the inner solar system at low speeds and carefully intersect the atmosphere of Mars. Ten such loads would deliver a billion tons of nitrogen, as much mass as a cubic kilometer of water, and 10,000 loads would deliver a full trillion tons.

The image at the top of this article shows a load of 100,000 chunks of nitrogen (shown as cubes but they could be in huge plastic bags.) Each chunk is about 10 meters across and weighs about 1,000 tons. By aiming these large loads of nitrogen ice so that they come in exactly horizontally at the high atmosphere of Mars over the desired areas, instead of impacting on Mars surface, there are no craters formed and all of the nitrogen is turned into gas and added to the atmosphere over an entry path of hundreds of kilometers. Very large amounts of heat, but no dangerous radiation, are created by these entries, which would occur many times a day and go on for over 100 years.

The entries could be targeted over the ice caps or glaciers and would easily melt them totally, as each entry produces as much radiant heat as a hydrogen bomb but with no dangerous radiation. Thus, the ice cap melting can be done by these repeated entry events, instead of a few, very dangerous cratering events. The fusion tugs back away from their loads before entry and head back to the outer solar system at high speed since they now have no load. Climatologists may have to hurry to get valuable ice cores of all the ice cap areas before they are melted to form a new, but initially shallow, Boreal Ocean and other bodies of water.

Easy-peasy then!

Corn, or maize, originated in southern Mexico, when it was domesticated from a wild cereal called teosinte, and the region is still home to the greatest diversity of the crop, including a unique variety that uses air as fertilizer:

For thousands of years, people from Sierra Mixe, a mountainous region in southern Mexico, have been cultivating an unusual variety of giant corn. They grow the crop on soils that are poor in nitrogen — an essential nutrient — and they barely use any additional fertilizer. And yet, their corn towers over conventional varieties, reaching heights of more than 16 feet.

A team of researchers led by Alan Bennett from UC Davis has shown that the secret of the corn’s success lies in its aerial roots — necklaces of finger-sized, rhubarb-red tubes that encircle the stem. These roots drip with a thick, clear, glistening mucus that’s loaded with bacteria. Thanks to these microbes, the corn can fertilize itself by pulling nitrogen directly from the surrounding air.

The Sierra Mixe corn takes eight months to mature — too long to make it commercially useful. But if its remarkable ability could be bred into conventional corn, which matures in just three months, it would be an agricultural game changer.

All plants depend on nitrogen to grow, and while there’s plenty of the element in the air around us, it’s too inert to be of use. But bacteria can convert this atmospheric nitrogen into more usable forms such as ammonia — a process known as fixation. Legumes, like beans and peas, house these nitrogen-fixing bacteria in their roots. But cereals, like corn and rice, largely don’t. That’s why American farmers need to apply more than 6.6 million tons of nitrogen to their corn crops every year, in the form of chemical sprays and manure.

John Durant’s Paleo Manifesto is neither paleo, nor a manifesto — and that’s not a bad thing.

I recently revisited Chapter 4, titled Moses the Microbiologist.

I highlighted these passages:

• However the books were actually written by multiple authors, include stories borrowed from neighboring cultures, sometimes diverge from the best history of the era, and weren’t compiled until long after Moses allegedly lived. Seen in that light, the story of Moses is more than the story of one man; it’s the collective memory of half the world’s people.

  Location: 740

• Jewish scholars count 613 commandments (248 do’s and 365 don’ts), with thousands of long-standing interpretations and implications for daily life.

  Location: 749

• How curious that one of those commandments ordered Jewish priests to wash their hands—one of the simplest and most effective forms of hygiene ever discovered—right at the moment in history when infectious disease was exploding. And this commandment came just after the part of the story where the Jewish people distinguish themselves as being impervious to plague.

  Location: 750

• The flight from Egypt is also the moment in the story when the Jewish people transition from being pastoral herders to urban dwellers. If there is one people who not only made the transition to living in cities but also developed a reputation for thriving in cities, it is the Jewish people. Jewish culture has survived for some 3,000 years—arguably the oldest non-isolated culture with significant permanence—which suggests that it contains features that have allowed it to persist through the Agricultural Age and helped Jews adapt to life in the big city.

  Location: 753

• Whether or not early agriculturalists realized it, many ancient cultural practices were adaptations against pathogens. For example, spices have antimicrobial properties, which made them a healthy addition to food in an era before refrigeration. It’s not a coincidence that equatorial ethnic cuisines are particularly spicy (food spoils faster in hot climates) and recipes for meat dishes tend to call for more spices than do vegetable dishes (meat spoils faster than plants). Water in early cities was often filthy, which helps explain the emergence of sterile alternatives such as wine (microbes can’t survive in alcohol) and hot tea (boiling kills microbes). Early people didn’t know that invisible bacteria were causing their cavities, but many still ended up using “toothbrushes”—wooden chewing sticks containing a natural antiseptic or treated with one.

  Location: 778

• In reading the Torah, one thing becomes immediately clear: life was rife with disease. Not only does the Torah describe pestilence and plague in a general sense, it also mentions dozens of distinct diseases and illnesses. Yet the Jewish people seem miraculously exempt from pestilence—when they obey God’s laws.

  Location: 808

• There’s much in the Law of Moses that remains mysterious or defies a simple explanation, but it is remarkable how much makes sense from a single point of view: infectious disease.

  Location: 814

• Some of the rules unambiguously address infectious disease, with priests explicitly playing the role of healer. For example, the laws concerning “leprosy” read like a medical text (Leviticus 13–14). Though the modern condition known as leprosy isn’t itself described, the laws help healer-priests discern between multiple skin diseases and determine the appropriate treatment. The…

  Location: 815

• immediate quarantine, washing, and in some cases hair removal. The laws also specify how to deal with “leprous” garments or dwellings. Garments had to be quarantined and washed; if that failed to halt the spread of infection, they had to be burned. Dwellings had to be emptied, contaminated stones had to be replaced, and the walls had to be…

  Location: 819

• Far beyond the laws on leprosy, it’s fair to say the Mosaic Law is obsessed with cleanliness, stipulating a lengthy code of personal hygiene and public health—accounting for some 15–20% of the 613 commandments. Though many commandments applied only to priests, the practices often came to permeate Jewish culture, fulfilling the injunction: “ ‘And you shall be to Me a kingdom of priests and a holy nation’ ” (Exodus 19:6). Jewish scholars have written about the importance of ritual hygiene in Judaism for a very long time (it’s one of the oldest themes in…

  Location: 822

• The Jewish hygiene code appears to be based on four…

  Location: 828

• First, certain people, animals, or things are inherently “unclean.” Inorganic matter alone, such as dirt, doesn’t make someone “unclean” in the literal sense of “dirty.” Uncleanliness comes from organic matter, such as corpses, bodily fluids, insects, and certain animals. In many cases what the Jews call…

  Location: 828

• Second, this “unclean” status is transferable through physical contact. In the same way that germs are transmissible, “unclean” things are…

  Location: 832

• Third, an “unclean” person or object could become “clean” again through various purification rituals. It was as if these cleansing rituals were able to “…

  Location: 834

• Fourth, individual “uncleanliness” affects the entire community. Akin to mandatory public health measures, the Mosaic Law applies to all Jews—and the text makes clear that Jews’ collective adherence to the Mosaic Law…

  Location: 836

• However, ineffective rules may have been the price of a generalized obsession with potential routes of infection, and such a mindset would lead to practices that are genuinely hygienic.

  Location: 844

• Honoring the dead benefited the living: quick burials make hygienic sense given how rapidly corpses decompose in a hot climate like that of the Middle East.

  Location: 855

• Showing a similar wariness of corpses, Jews were not allowed to eat any animal that either died of its own accord or was killed by wild beasts (Leviticus 7:24, 11:39–40). Animals weakened by disease are more likely to drop dead or be picked off by predators, and, as with humans, a corpse lying out for long enough becomes a literal breeding ground for pathogens.

  Location: 858

• With so many people dropping dead from disease, cannibalism was a recipe for infection—thus an ancient indigenous method of honoring the dead turned into an unthinkable taboo, used in curses as a sign of the ultimate defilement (Leviticus 26:29; Deuteronomy 28:52–57).

  Location: 862

• The result was an ancient form of food inspection: the carcass and internal organs had to be examined for defects, signs of disease, or anything that might have caused the animal to die of its own accord in the near future. Later in history, Jews even inflated the lungs and submerged them in water to look for any leaks—a telltale sign of tuberculosis.

  Location: 867

• Avoiding vermin and insects like the plague, as it were, would have been a simple and effective rule to avoid infectious disease.

  Location: 878

• The “unclean” lizards and amphibians (Leviticus 11:29–30) are low disease risks, but they do perform a useful function: They eat scads of insects, which carry disease.

  Location: 888

• The prohibitions against eating birds of prey appear to follow a similar ecological logic (Leviticus 11:13–19). Birds of prey eat vermin and other pests. Carrion fowl, such as the forbidden vultures, conveniently dispose of corpses (Leviticus 11:13–19), as do four-pawed carnivorous mammals (Leviticus 11:27).

  Location: 890

• By excluding cats from the dinner menu, even the American diet reveals the influence of protecting a species that eats vermin.

  Location: 896

• Zoroastrianism explicitly stipulated that all human corpses must be taken to a mountaintop, chained to the ground, and left to be devoured by corpse-eating wild dogs and birds (Avesta, Vendidad 6:44–51).

  Location: 899

• Any direct contact with an unclean person (or thing) made someone (or something) unclean. For example, if a rodent carcass touched household objects or fell into food or water, it all became unclean (Leviticus 11:32–38). The idea that germs were transferable by even the slightest physical touch may seem obvious today, but it was an astonishing inference thousands of years before the formal discovery of the germ theory of disease in the late nineteenth century.

  Location: 923

• As a result of water’s dual nature (easily transmitting uncleanliness, yet itself a source of purification), Jews became fixated on ensuring the purity of their water supply.

  Location: 932

• One of those purification rituals requires an unclean person to take both hands and rinse them in clean water (Exodus 30:17–21; Leviticus 15:11; Deuteronomy 21:6).

  Location: 940

• Another form of “ritual” purification required Jews to immerse themselves in a pool of water—also known as taking a bath.

  Location: 947

• Observing the Sabbath was very important: the penalty for not observing a day of rest—taking a vacation day—was death (Exodus 31:12–17). In preparation, Jews had to undergo multiple purification rituals: take a bath, wash their hands, launder their clothes, and clean their home.

  Location: 954

• The Jewish people also knew about at least one form of sterilization: fire.

  Location: 957

• Here’s how to make that “water of purification”: slaughter a cow, burn it whole, and throw some “cedar wood and hyssop and scarlet” into the fire. Then take the ashes and add water (Numbers 19). Water, ash, and animal fat are ingredients for soap.

  Location: 961

• Even though Jews stopped sacrificial slaughter thousands of years ago, Jewish rabbis offered a different interpretation of “water of purification”: scalding hot water (Talmud, Avodah Zarah 75b). As a result, Jews sterilized their dishes and eating utensils by submerging them in water that had been brought to a boil.

  Location: 965

• Earthenware pots, which are porous and difficult to sterilize, had to be broken and could never be used again if they became unclean (Leviticus 6:28, 11:33). In contrast, bronze pots could be scoured and washed (Leviticus 6:28). Items made from wool, linen, leather, and wood could usually be washed (Leviticus 11:32, 13:53–59, 15:12; Numbers 31:20), though sometimes they had to be destroyed with fire (Leviticus 13:47–52).

  Location: 968

• (In fact, this passage in Numbers became the basis for many rules governing any type of contact with Gentiles and their possessions, which were assumed to be unclean. This wariness of contact with filthy foreigners, plus an obsession with hand washing, would have given Jews an advantage in commerce, both as middlemen—as hubs in trade networks—and long-distance merchants visiting lands with novel pathogens—key edges in trade networks. Another people similarly distinguished are the Parsis of India; curiously, they are some of the last remaining followers of Zoroastrianism.)

  Location: 977

• Not only did the physical plunder have to be cleaned of infection, so did the captive women (all the men were killed). Female captives were forced to shave their heads and trim their fingernails (Deuteronomy 21:10–12),

  Location: 981

• Only virgin women could be captured; all other women had to be killed (Numbers 31:15–18). This was a direct result of past experience—see “the Peor incident” (Numbers 25)—when the Jewish soldiers kept all the conquered women alive, had sex with them, and brought a plague upon themselves.

  Location: 986

• Early agricultural sex cults—of which there were more than a few—tended to die out. Religions that placed restrictions on our sexual impulses did not.

  Location: 995

• The connection between cervical cancer and sexual activity was discovered by observing that celibate nuns were unafflicted by cervical cancer, whereas the affliction was relatively common among prostitutes.

  Location: 1006

• Follow God’s hygiene rules and emerge unscathed from the great plagues that destroy rival peoples: a sign of God’s favor. Disobey God’s hygiene rules and be struck down by pestilence: a sign of God’s displeasure.

  Location: 1034

• In Europe, from the Black Death onward, Fishberg uncovered reports of Jewish people dying at lower rates than Christians during major epidemics: a typhus epidemic in 1505; fevers in Rome in 1691; dysentery in Nimègue in 1736; and typhus in Langeons in 1824. By the nineteenth century, public health statistics revealed not only that the effect was real, but that it was enormous: a ten-year advantage in life expectancy in many European cities. This disparity was even more remarkable considering that Jews were often forced to live in crowded and damp urban ghettos—places conducive to the spread of disease.

  Location: 1076

I was recently reminded of Feynman’s anecdote about an early wartime engineering job he had, recounted in Surely You’re Joking, Mr. Feynman!, and that nudged me to move James Gleick’s biography, Genius: The Life and Science of Richard Feynman, to the front of my reading queue.

Since I had the Kindle version, I was able to export my “highlights” — although that required a third-party tool called Bookcision:

• The adult Feynman asked: If all scientific knowledge were lost in a cataclysm, what single statement would preserve the most information for the next generations of creatures? Location: 705
• “All things are made of atoms—little particles that move around in perpetual motion, attracting each other when they are a little distance apart, but repelling upon being squeezed into one another,” Location: 707
• Heat had seemed to flow from one place to another as an invisible fluid—“phlogiston” or “caloric.” But a succession of natural philosophers hit on a less intuitive idea—that heat was motion. Location: 725
• In Switzerland Daniel Bernoulli derived Boyle’s law by supposing that pressure was precisely the force of repeated impacts of spherical corpuscles, and in the same way, assuming that heat was an intensification of the motion hither and thither, he derived a link between temperature and density. Location: 728
• Visitors less interested in science could pay to see an unemployed actress named Sally Rand dance with ostrich-feather fans. Location: 781
• When there are a dozen Babe Ruths, there are none. Location: 809
• They went to the Egyptian section, first studying glyphs in the encyclopedia so that they could stand and decode bits of the chiseled artifacts, a sight that made people stare. Location: 869
• In just over a decade of full-scale commercial production, the radio had penetrated nearly half of American households. Location: 872
• If a boy named Morrie Jacobs told him that the cosine of 20 degrees multiplied by the cosine of 40 degrees multiplied by the cosine of 80 degrees equaled exactly one-eighth, he would remember that curiosity for the rest of his life, and he would remember that he was standing in Morrie’s father’s leather shop when he learned it. Location: 892
• For now, knowledge was scarce and therefore dear. Location: 896
• Richard spent fifteen dollars on a special entrance examination for Columbia University, and after he was turned down he long resented the loss of the fifteen dollars. MIT accepted him. Location: 939
• Mathematics is always where they begin, for no other school course shows off their gifts so clearly. Location: 958
• The theories must make reasonably good predictions about experiments. That is all. Location: 999
• It follows the path of least time. (Fermat, reasoning backward, surmised that light must travel more slowly in denser media. Later Newton and his followers thought they had proved the opposite: that light, like sound, travels faster through water than through air. Fermat, with his faith in a principle of simplicity, was right.) Location: 1057
• “Our friend Dirac, too, has a religion, and its guiding principle is ‘There is no God and Dirac is His prophet.’” Location: 1067
• Having chosen a fraternity, one instantly underwent a status reversal, from an object of desire to an object of contempt. Location: 1147
• Fortunately they had calculators, a new kind that replaced the old hand cranks with electric motors. Location: 1432
• In Germany a young would-be theorist could spend his days hiking around alpine lakes in small groups, playing chamber music and arguing philosophy with an earnest Magic Mountain volubility. Location: 1449
• Feynman had developed an appetite for new problems—any problems. He would stop people he knew in the corridor of the physics building and ask what they were working on. Location: 1535
• The committee had seen its share of one-sided applicants but had never before admitted a student with such low scores in history and English on the Graduate Record Examination. Feynman’s history score was in the bottom fifth, his literature score in the bottom sixth; and 93 percent of those who took the test had given better answers about fine arts. Location: 1565
• We have no definite rule against Jews but have to keep their proportion in our department reasonably small because of the difficulty of placing them. Location: 1570
• In the close, homogenous university communities, code words were attractive or nice. Location: 1592
• “Surely you’re joking, Mr. Feynman!” Location: 1798
• Feynman quietly nursed an attachment to a solution so radical and straightforward that it could only have appealed to someone ignorant of the literature. Location: 1851
• Implicit in Feynman’s attitude was a sense that the laws of nature were not to be discovered so much as constructed. Location: 1860
• They assured their readers that these were analogies, though analogies with the newly formidable weight of mathematical rectitude. Location: 1868
• Another was John Tukey, who later became one of the world’s leading statisticians. Location: 1898
• Seventeen years later, in 1956, the flexagons reached Scientific American in an article under the byline of Martin Gardner. “Flexagons” launched Gardner’s career as a minister to the nation’s recreational-mathematics underground, through twenty-five years of “Mathematical Games” columns and more than forty books. Location: 1917
• They discovered that Feynman could read to himself silently and still keep track of time but that if he spoke he would lose his place. Tukey, on the other hand, could keep track of the time while reciting poetry aloud but not while reading. Location: 1934
• But in the inverse case, when water is sucked in, there are no jets. The water is not organized. It enters the nozzle from all directions and therefore applies no force at all. Location: 1989
• If there is a disease whose symptom is the belief in the ability of logic to control vagarious life, it afflicted Feynman, along with his chronic digestive troubles. Even Arline Greenbaum, sensible as she was, could spark flights of reason in him. Location: 2122
• A movie showing a drop of ink diffusing in a glass of water looks wrong when run backward. Yet a movie showing the microscopic motion of any one ink molecule would look the same backward or forward. Location: 2181
• “You Americans!” he said. “Always trying to find a use for something.” Location: 2379
• In preparing for his oral qualifying examination, a rite of passage for every graduate student, he chose not to study the outlines of known physics. Instead he went up to MIT, where he could be alone, and opened a fresh notebook. On the title page he wrote: Notebook Of Things I Don’t Know About. Location: 2392
• When he told a university dean that his fiancée was dying and that he wanted to marry her, the dean refused to permit it and warned him that his fellowship would be revoked. Location: 2493
• Not so much as a grain of uranium 235 existed in pure form. Location: 2510
• In one way or another, by the time the United States entered the war in December, one-fourth of the nation’s seven-thousand-odd physicists had joined a diffuse but rapidly solidifying military-research establishment. Location: 2537
• Graduate students were being pressed into service with the help of a simple expedient—Princeton called a halt to most degree work. Location: 2585
• To physicists Oppenheimer’s command of Sanskrit seemed a curiosity; to General Groves it was another sign of genius. Location: 2908
• If Feynman says it three times, it’s right. Location: 3029
• the Bethe Bible, the three famous review articles on nuclear physics, had provided the entire content of MIT’s course. Location: 3061
• Cosmic rays alone sparked enough fission to make uranium 235 noticeably hotter in the high altitudes of Los Alamos than in sea-level laboratories. Location: 3075
• He told them he could spot wrong results even when he had no idea what was right—something about the smoothness of the numbers or the relationships between them. Location: 3223
• “It’s twenty-three hundred and four. Don’t you know how to take squares of numbers near fifty?” Location: 3240
• Bethe knew instinctively, as did Feynman, that the difference between two successive squares is always an odd number, the sum of the numbers being squared. Location: 3245
• He had simply added the first four terms in his head—that was enough for two decimal places. Location: 3259
• The manufacturers of such equipment—the International Business Machines Corporation already preeminent among them—considered the scientific market to be negligible. Location: 3286
• “He is a second Dirac,” Wigner said, “only this time human.” Location: 3385
• People are predictable. They tend to leave safes unlocked. They tend to leave their combinations at factory settings such as 25-0-25. They tend to write down the combinations, often on the edge of their desk drawers. They tend to choose birthdays and other easily remembered numbers. Location: 3482
• Experimentalists assembled perfect shining cubes of uranium into near-critical masses by hand. Location: 3618
• Feynman’s first visit to Oak Ridge was his first ride on an airplane, and the thrill was heightened by his special-priority military status on the flight, with a satchel of secret documents actually strapped to his back under his shirt. Location: 3674
• When he comes in, tell him Johnny von Neumann called.) Location: 3726
• He estimated that a Hiroshima bomb in mass production would cost as much as one B-29 superfortress bomber. Its destructive force surpassed the power of one thousand airplanes carrying ten-ton loads of conventional bombs. Location: 3747
• Before the war the government had paid for only a sixth of all scientific research. By the war’s end the proportions had flipped: only a sixth was financed by all nongovernment sources combined. Location: 3811
• To have worked on the bomb gave a scientist a stature matched only by the Nobel Prize. By comparison it was nothing to have created radar at the MIT Radiation Laboratory, though by a plausible calculus radar had done more to win the war. Location: 3816
• Unlike most of the Ivy League universities, Cornell had accepted women as undergraduates since its founding, after the Civil War, though they automatically matriculated in the College of Home Economics. Location: 3870
• Feynman’s spacecraft would use the outer edges of the earth’s atmosphere as a sort of warm-up track and accelerate as it circled the earth. Location: 3983
• Cornell’s 1946 fall-term enrollment was its largest ever, nearly double prewar levels. Location: 4022
• Dyson’s war could hardly have been more different from Feynman’s. The British war organization wasted his talents prodigiously, assigning him to the Royal Air Force bomber command in a Buckinghamshire forest, where he researched statistical studies that were doomed, when they countered the official wisdom, to be ignored. The futility of this work impressed him. He and others in the operational research section learned—contrary to the essential bomber command dogma—that the safety of bomber crews did not increase with experience; that escape hatches were too narrow for airmen to use in emergencies; that gun turrets slowed the aircraft and bloated the crew sizes without increasing the chances of surviving enemy fighters; and that the entire British strategic bombing campaign was a failure. Location: 4293
• Dyson saw the scattershot bomb patterns in postmission photographs, saw the Germans’ ability to keep factories operating amid the rubble of civilian neighborhoods, worked through the firestorms of Hamburg in 1943 and Dresden in 1945, and felt himself descending into a moral hell. Location: 4300
• “Other people publish to show how to do it, but Julian Schwinger publishes to show you that only he can do it.” Location: 4750
• Caltech made itself the American center of systematic earthquake science; one of its young graduates, Charles Richter, devised the ubiquitous measurement scale that carries his name. Location: 5094
• The school moved quickly into aeronautic science, and a group of enthusiastic amateurs firing off rockets in the hills about the Rose Bowl became, by 1944, the Jet Propulsion Laboratory. Location: 5096
• You have only told what a word means in terms of other words. Location: 5140
• Science is a way to teach how something gets to be known, what is not known, to what extent things are known (for nothing is known absolutely), how to handle doubt and uncertainty, what the rules of evidence are, how to think about things so that judgments can be made, how to distinguish truth from fraud, and from show. Location: 5154
• susurrus Location: 5247
• The main rule is to treat the women with disrespect. Location: 5258
• noetic Location: 5264
• The year before, Schrieffer had listened intently as Feynman delivered a pellucid talk on the two phenomena: the problem he had solved, and the problem that had defeated him. Schrieffer had never heard a scientist outline in such loving detail a sequence leading to failure. Location: 5502
• It fell to Schrieffer to transcribe Feynman’s talk for journal publication. He did not quite know what to do with the incomplete sentences and the frank confessions. He had never read a journal article so obviously spoken aloud. So he edited it. But Feynman made him change it all back. Location: 5510
• a Caltech experimenter told Feynman about a result reached after a complex process of correcting data, Feynman was sure to ask how the experimenter had decided when to stop correcting, and whether that decision had been made before the experimenter could see what effect it would have on the outcome. Location: 5561
• Sometimes it was not clear whether Feynman’s lightning answers came from instantaneous calculation or from a storehouse of previously worked-out—and unpublished—knowledge. Location: 5753
• The Chicago astrophysicist Subrahmanyan Chandrasekhar independently produced Feynman’s result—it was part of the work for which he won a Nobel Prize twenty years later. Feynman himself never bothered to publish. Location: 5759
• “I am suggesting that anyone who is transcendentally great as a scientist is likely also to have personal qualities that ordinary people would consider in some sense superhuman.” Location: 5780
• So many of his witnesses observed the utter freedom of his flights of thought, yet when Feynman talked about his own methods he emphasized not freedom but constraints. Location: 5912
• “The gravitational force is weak,” he said at one conference, introducing his work on quantizing gravity. “In fact, it’s damned weak.” At that instant a loudspeaker demonically broke loose from the ceiling and crashed to the floor. Feynman barely hesitated: “Weak—but not negligible.” Location: 6435
• There is a great deal of “activity in the field” these days, but this “activity” is mainly in showing that the previous “activity” of somebody else resulted in an error or in nothing useful or in something promising. Location: 6469
• He talked about DNA (fifty atoms per bit of information) and about the capacity of living organisms to build tiny machinery, not just for information storage but for manipulation and manufacturing. Location: 6498
• He concluded by offering a pair of one-thousand-dollar prizes: one for the first microscope-readable book page shrunk 25,000 times in each direction, and one for the first operating electric motor no larger than a 1/64th-inch cube. Location: 6505
• Learn by trying to understand simple things in terms of other ideas—always honestly and directly. Location: 6533
• Then when you have learned what an explanation really is, you can then go on to more subtle questions. Location: 6535
• If, in some cataclysm, all of scientific knowledge were to be destroyed, and only one sentence passed on to the next generation of creatures, what statement would contain the most information in the fewest words? I believe it is the atomic hypothesis (or the atomic fact, or whatever you wish to call it) that all things are made of atoms—little particles that move around in perpetual motion, attracting each other when they are a little distance apart, but repelling upon being squeezed into one another. Location: 6557
• What we really cannot do is deal with actual, wet water running through a pipe. That is the central problem which we ought to solve some day. Location: 6593
• “I’ve spoken to some of those students in recent times, and in the gentle glow of dim memory, each has told me that having two years of physics from Feynman himself was the experience of a lifetime.” Location: 6643
• As the course wore on, attendance by the kids at the lectures started dropping alarmingly, but at the same time, more and more faculty and graduate students started attending, so the room stayed full, and Feynman may never have known he was losing his intended audience. Location: 6645
• Nature uses only the longest threads to weave her pattern, so each small piece of the fabric reveals the organization of the entire tapestry. Location: 6689
• “None of the entities that appear in fundamental physical theory today are accessible to the senses. Even more … there are phenomena that apparently are not in any way amenable to explanation in terms of things, even invisible things, that move in the space and time defined by the laboratory.” Location: 6700
• “Questions about a theory which do not affect its ability to predict experimental results correctly seem to me quibbles about words.” Location: 6707
• What can you explain that you didn’t set out to explain? Location: 6752
• I’m not answering your question, but I’m telling you how difficult a why question is. You have to know what it is that you’re permitted to understand … and what it is you’re not. Location: 6779
• I really can’t do a good job—any job—of explaining the electromagnetic force in terms of something you’re more familiar with, because I don’t understand it in terms of anything else that you’re more familiar with. Location: 6792
• He told reporters that he planned to spend his third of the $55,000 prize money to pay his taxes on his other income (actually he used it to buy a beach house in Mexico). Location: 6952
• “If you give more money to theoretical physics,” he added, “it doesn’t do any good if it just increases the number of guys following the comet head. So it’s necessary to increase the amount of variety … and the only way to do it is to implore you few guys to take a risk with your lives that you will never be heard of again, and go off in the wild blue yonder and see if you can figure it out.” Location: 7004
• Dr. Crick thanks you for your letter but regrets that he is unable to accept your kind invitation to:
  ☐ send an autograph
  ☐ help you in your project
  ☐ provide a photograph
  ☐ read your manuscript
  ☐ cure your disease
  ☐ deliver a lecture
  ☐ be interviewed
  ☐ attend a conference
  ☐ talk on the radio
  ☐ act as chairman
  ☐ appear on TV
  ☐ become an editor
  ☐ speak after dinner
  ☐ write a book
  ☐ give a testimonial
  ☐ accept an honorary degree
  Location: 7011
• I. I. Rabi once said that physicists are the Peter Pans of the human race. Feynman clutched at irresponsibility and childishness. He kept a quotation from Einstein in his files about the “holy curiosity of inquiry”: “this delicate little plant, aside from stimulation, stands mainly in need of freedom; without this it goes to wrack and ruin without fail.” Location: 7077

A group of Japanese researchers has discovered that neural inflammation caused by our innate immune system plays an unexpectedly important role in stress-induced depression:

A group of Japanese researchers has discovered that neural inflammation caused by our innate immune system plays an unexpectedly important role in stress-induced depression:

Previous research had already hinted at the link between inflammation and depression: increased levels of inflammation-related cytokines in the blood of patients suffering from depression, activation of microglia (inflammation-related cells in the brain) in depressive patients, and a high percentage of depression outbreaks in patients suffering from chronic inflammatory disease. However, the exact relationship between depression and inflammation still contains many unknowns. Psychological stress caused by social and environmental factors can trigger a variety of changes in both mind and body. Moderate levels of stress will provoke a defensive response, while extreme stress can lower our cognitive functions, cause depression and elevated anxiety, and is a risk factor for mental illnesses. The research team focused on repeated social defeat stress (a type of environmental stress) with the aim of clarifying the mechanism that causes an emotional response to repeated stress.

First, they looked at changes of gene expression in the brain caused by repeated social defeat stress and found that repeated stress increased a putative ligand for the innate immune receptors TLR2 and TLR4 (TLR2/4) in the brain. Their next step was to investigate the role of TLR2/4 in repeated stress using a mouse with the TLR2/4 genes deleted. They found that TLR2/4-deficient mice did not show social avoidance or extreme anxiety when exposed to repeated stress. Repeated stress usually triggers microglial activation in specific areas of the brain such as the medial prefrontal cortex, causing impaired response and atrophy of neurons, but these responses were not present in the TLR2/4-deficient mice. The research team then developed a method to selectively block the expression of TLR2/4 in the microglia of specific areas of the brain. By blocking the expression of TLR2/4 in the microglia of the medial prefrontal cortex, they managed to suppress depressive behavior in response to repeated social defeat stress. They found that repeated stress induced the expression of inflammation-related cytokines IL-1a and TNFa in the microglia of the medial prefrontal cortex via TLR2/4. The depressive behavior was suppressed by treating the medial prefrontal cortex with neutralizing antibodies for the inflammation-related cytokines. These results show that repeated social defeat stress activates microglia in the medial prefrontal cortex via the innate immune receptors TLR2/4. This triggers the expression of inflammation-related cytokines IL-1a and TNFa, leading to the atrophy and impaired response of neurons in the medial prefrontal cortex, and causing depressive behavior.

If you recently enjoyed Feynman’s anecdote about an early wartime engineering job he had, you should know that Amazon’s Prime Reading program just added Surely You’re Joking, Mr. Feynman! to its list of free Kindle reads.