Mickey is a trained engineer. If he had been an engineer, the world would be more peaceful. However, he became interested in the industrial use of chemistry. 192 1 year, he studied a compound called tetraethyl lead during his work in General Motors Research Company in Dayton, Ohio, and found that it can greatly reduce the vibration phenomenon, which is called engine knock.
By the beginning of the 20th century, everyone knew that lead was dangerous, but it still existed in various forms in consumer goods. Canned food is sealed with solder lead; Water is usually stored in lead tanks; Lead arsenate is used as an insecticide and sprayed on fruits. Lead is even a component of toothpaste tubes. Almost every product will add a little lead to consumers' health. However, it is the lead added in gasoline that people have the most opportunities and the longest contact time.
Lead is a neurotoxin. If the lead content in the body is too high, it will cause irreparable damage to the brain and central nervous system. Excessive exposure to lead can lead to many diseases, including blindness, insomnia, renal failure, deafness, cancer, paralysis and convulsions. During an acute attack, people will suddenly have horrible hallucinations, which will make patients and others unprepared. Generally speaking, this symptom will lead to coma or death. No one wants to let his body take in too much lead.
On the other hand, lead is easy to extract and mine, and the profit of mass production is extremely high-tetraethyl lead can really prevent engine knocking. So, 1923, the three largest companies in the United States-General Motors, Dupont and Mobil Oil Company in New Jersey-set up a joint venture called Tetraethyl Lead Gasoline Company (hereinafter referred to as Tetraethyl Lead Company), which produced as much tetraethyl lead as the world wanted. It turns out the world needs a lot. They call this additive "tetraethyl" because it sounds more pleasant and contains no toxic substances such as lead. February 1923, 1, they put their names on the market (in more ways than most people know) and let the public accept them.
Front-line workers almost immediately showed symptoms such as unstable walking and disordered function, which was a sign of poisoning soon after. Company 4 B has also implemented a policy of almost immediate and resolute denial as if nothing had happened, which has been effective for decades. As Sharon Birch McGrane pointed out in her book "Prometheus in the Laboratory, a history of industrial chemistry", if employees in any factory suffer from incurable hallucinations, the spokesperson will brazenly tell reporters: "The reason why these people are insane is probably because they work too hard." At the beginning of leaded gasoline production, at least 15 workers died, and countless people fell ill, often seriously ill. The specific figures are unknown, because enterprises can almost always cover up the past and never disclose embarrassing information such as leakage, leakage and poisoning. However, sometimes it is impossible to suppress the news-especially 1924. Within a few days, in a poorly ventilated place, five production workers died and 35 workers were permanently disabled.
With the rumors of the danger of new products, in order to dispel people's worries, Thomas Mijili, the inventor of tetraethyl lead gasoline, decided to give a live performance in front of reporters. While talking about how the company ensured safety, he poured leaded gasoline into his hand and put a beaker of this gasoline in front of his nose for 60 seconds, claiming that he could do it every day without any harm. In fact, Midgley is well aware of the dangers of lead poisoning: he was seriously ill from too much contact a few months ago, and now he will never go near that thing again, except in front of reporters, as long as possible.
Encouraged by the success of leaded gasoline, Midgley turned his attention to another technical problem of that era. In the 1920s, refrigerators used toxic and dangerous gases, which often leaked and had great risks. 1929, a refrigerator leak occurred in a hospital in Cleveland, Ohio, causing more than 100 deaths. Midgley set out to invent a gas that is very stable, nonflammable, non-corrosive and safe to inhale. With the instinct of almost never regretting doing things, he invented chlorofluorocarbons.
Few industrial products are accepted so quickly and unfortunately. In the early 1930s, chlorofluorocarbons were put into production. As a result, they were used for a thousand purposes, from automobile air conditioners to deodorant sprays. It took half a century before people discovered that this thing was devouring stratospheric ozone. You will understand that this is not a good thing.
Ozone is a form of oxygen, and each molecule contains three atoms instead of the usual two. Its chemical properties are a bit strange: it is a harmful substance on the ground, but it is a beneficial substance in the stratosphere because it absorbs dangerous ultraviolet radiation. However, the beneficial amount of ozone is not very large. Even if it is evenly distributed in the stratosphere, it can only form a layer about two millimeters thick. This is why it is easily disturbed.
The amount of chlorofluorocarbons is also very small, only about 10 billion in the whole atmosphere, but this gas is very destructive. 1 kg chlorofluorocarbons can capture and destroy 70,000 kg of ozone in the atmosphere. Chlorofluorocarbons (CFCs) have been put on hold for a long time-about a century on average-and have been causing damage. It absorbs a lot of heat. The ability of chlorofluorocarbon molecules to increase the greenhouse effect is about 1000 times stronger than that of carbon dioxide molecules-of course, carbon dioxide itself is an expert in aggravating the greenhouse effect. In a word, chlorofluorocarbons may prove to be the worst invention of the 20th century.
Midgley will never know this. He was dead before people realized the destructive power of chlorofluorocarbons. His death itself is extremely unusual. After Midgley was disabled by polio, he invented a mechanical device, which used a series of electric pulleys to automatically help him lift himself or turn over in bed. 1944, when the machine started, he was entangled in the rope and suffocated.
If you are interested in dating things, the University of Chicago in the 1940s is the place you should go. Willard Libby is about to invent radiocarbon dating method, which enables scientists to accurately date bones and other organic fragments, which was impossible in the past. By this time, the reliable age only reached the first dynasty of Egypt-around 3000 BC. For example, when the last batch of ice sheets will retreat, and when French Kroma farmers will decorate Lascaux Cave, no one can say for sure.
Libby's method is very versatile, so he won the Nobel Prize of 1960. This method is based on the recognition that carbon isotope-carbon-14 exists in organisms. When living things die, isotopes begin to decay at a measurable rate. The half-life of carbon-14 is about 5600 years-that is, the time required for half of any sample to disappear-so by determining the decay degree of a specific carbon sample, Libby can effectively lock the age of an object, although within a certain limit. After eight half lives, the original radioactive carbon is only 0.39%. This quantity is too small to be calculated reliably, so the carbon-14 dating method is only applicable to celestial bodies with an age of less than 40 thousand years.
Interestingly, with the widespread use of this technology, some defects are increasingly exposed. First of all, it is found that there is a basic component called decay constant in Libby formula, and the error is 3%. By this time, thousands of calculations have been made all over the world. Scientists decided to keep this inaccurate constant instead of correcting every calculation result. "Well," said Tim flannery, "you only need to subtract about 3% from every radiocarbon dating you see today." The problem is not completely solved. It was soon discovered that the samples of carbon-14 were easily polluted by carbon in other places-for example, a little plant collected with the samples was not noticed. For samples that are not too old-samples less than about 20000-a little pollution is not always important, but for samples that are too old, this may be a serious problem because there are too few atoms left in the statistics. To borrow Franganari's words, in the first case, it is like 1000 dollars1; In the second case, it's like 1 dollar is missing from the only $2.
Moreover, Libby's method is based on the assumption that the content of carbon-14 in the atmosphere and the speed of biological absorption of this substance are constant throughout the historical process. That was not the case. We now know that the content of carbon-14 in the atmosphere changes, depending on whether the earth's magnetic field can effectively change the direction of cosmic rays; For a long time, the range of change may be great. This means that some ages determined by carbon-14 dating method are more uncertain than others. In uncertain years, there is a period of time around the first arrival of mankind in America. This is one of the reasons why this issue is always controversial.
Finally, perhaps surprisingly, due to seemingly unrelated external factors, such as the diet structure of animals, the calculation results may be completely meaningless. Recently, a case caused a wide and fierce debate, that is, whether syphilis originated in the New World or the Old World. Archaeologists in Hull found that monks in monasteries suffered from syphilis. The initial conclusion is that monks were infected with syphilis before Columbus sailed. However, this conclusion was questioned because scientists found that they ate a lot of fish, which made their bones look older than their actual age. Monks may have syphilis, but the question of how and when they got it seems easy to solve, but it has not been solved yet.
Because there are many shortcomings in the dating method of carbon-14, scientists have invented other methods to date ancient materials, including thermoluminescence dating and electron spin * * * vibration dating. The former is used to determine the number of electrons remaining in the soil; The latter bombards the sample with electromagnetic waves to measure the vibration of electrons. However, even with the best method, you can't date anything over 200,000 years old, and you can't date inorganic substances like rocks at all. However, it is certainly necessary to determine the age of our planet.
The problem with dating rocks is that almost everyone in the world gave up hope. If it weren't for a staunch British professor named Arthur Holmes, the exploration might have stopped completely.
Holmes is very brave in overcoming difficulties and achieving success. In the 1920s, when his career was in full swing, geology was no longer popular-physics was a hot science of that era, and the funds were seriously insufficient, especially in Britain, its spiritual birthplace. For many years, he was the only member of the Geology Department of Durham University. In order to date rocks, he often has to borrow or piece together equipment. Once, in order to wait for the school to provide him with a simple adder, his calculation work was delayed by 1 year. Sometimes, in order to earn money to support his family, he had to stop his academic work completely-once he opened an antique shop in Newcastle, and sometimes he couldn't even pay the annual membership fee of 5 pounds for the Geological Society.
The method used by Holmes in his research work is not complicated in theory, and it comes directly from the process first discovered by ernest rutherford in 1904, that is, some atoms decay from one element to another at a predictable speed, so this process can be used as a clock. If you know how long it takes for potassium -40 to change into argon -40, and then measure the contents of these two elements in the sample, you can get the age of that substance. Holmes's contribution is to determine the age of rocks by measuring the rate at which uranium decays into lead, so that-he hopes-the age of the earth can be determined.
However, there are many technical difficulties to overcome. Holmes also needs-at least he will be happy to have-an advanced instrument that can accurately measure small samples, and we already know that all he can get is a simple adder. Therefore, he can confidently claim in 1946 that the earth has existed for at least 3 billion years, and probably longer. This is quite a remarkable achievement. Unfortunately, he once again encountered a huge obstacle: his scientific colleagues were very conservative and refused to recognize his achievements. Although many people are willing to appreciate his method, they think that he has not obtained the age of the earth, but only the age of the substances that make up the earth.
At this time, Harrison Brown of the University of Chicago invented a new method to calculate lead isotopes in igneous rocks (that is, rocks formed by heating, not rocks formed by deposition). Realizing that the work was rather boring, he gave it to young Claire Patterson as his thesis project. He assured Peterson that it would be "a piece of cake" to determine the age of the earth with his new method. In fact, this work takes several years.
1948, Peterson began to work on this project. Compared with the colorful and advancing history of Thomas Midgley, Peterson's work of dating the earth is a bit mediocre. For seven years, first at the University of Chicago, then at the California Institute of Technology (1952), he worked hard in a sterile laboratory, carefully selected samples of ancient rocks and accurately determined the lead/uranium ratio.
The problem with dating the earth is that you need to have extremely old rocks, which contain crystals of lead and uranium, almost as old as this planet-if the rocks are much younger, the measured age will obviously be younger, thus drawing the wrong conclusion that really old rocks are hard to find on the earth. By the end of 1940s, no one knew why. In fact, it is incredible that no one can reasonably explain the whereabouts of ancient rocks on earth until the space age. The answer lies in plate tectonics, and of course we will talk about this problem. At the same time, Peterson can only understand all this in the case of very limited materials. Finally, it suddenly occurred to him that the problem of lack of rocks can be bypassed by rocks outside the earth. He turned his attention to meteorites.
He put forward a hypothesis-a far-sighted hypothesis, which proved to be very correct, that is, many meteorites are actually building materials left over from the early solar system, so they have retained the original internal chemical structure to some extent. By dating these wandering rocks, you have (almost) dated the earth.
However, on the whole, it is easier said than done. The number of meteorites is small, so it is difficult to collect meteorite samples. Moreover, Brown's measurement method pays too much attention to details and needs to be improved. The biggest problem is that as long as Peterson's samples come into contact with the air, they will be inexplicably polluted by lead in the atmosphere. It is for this reason that he finally established a sterile laboratory-the first sterile laboratory in the world, at least on one material.
Peterson worked hard for seven years before collecting samples that could be used for the final test. 1953 In the spring, he sent the sample to Argonne National Laboratory in Illinois. He got a new mass spectrometer in time, which can be used to find and determine trace uranium and lead hidden in ancient crystals. Peterson finally came to the conclusion. He was so excited that he drove directly to his childhood home in Iowa and asked his mother to take him to the hospital because he thought he had a heart attack.
Shortly thereafter, at a conference in Wisconsin, Peterson announced that the exact age of the earth was 4.55 billion years (with an error of 70 million years)-McGland said appreciatively, "This number has not changed after 50 years." After 200 years of hard work, the earth finally has an age.
Peterson turned his attention to the problem of lead in the atmosphere almost immediately. He was surprised to find that those little people who knew the effects of lead on human body were almost all wrong or misleading-not surprising, because every study on the effects of lead in the past 40 years was funded by the manufacturers of lead additives.
In one such study, a doctor without special training in chemical pathology undertook a five-year plan. According to the plan, he asked volunteers to inhale or swallow more and more lead, and then tested their urine and urine. Unfortunately, doctors don't seem to understand that lead will not be excreted as waste, but will only accumulate in bones and blood-that's why lead is dangerous. He didn't have a bone examination or a blood test. As a result, lead was declared to have no effect on health.
Peterson quickly confirmed that there is a lot of lead in the atmosphere-in fact, there is still a lot of lead because it is not fade away-about 90% of which comes from the exhaust pipe of cars, but he can't prove it. He needs a method to compare the current concentration of lead in the atmosphere with that before the commercial production of tetraethyl lead in 1923. It suddenly occurred to him that ice cores might provide this answer.
As we all know, in places like Greenland, the annual snow layer is very distinct (because the seasonal temperature difference makes the color slightly different from winter to summer). As long as you count these layers and measure the lead content in each layer, you can calculate the lead concentration in the global atmosphere at any time for hundreds or even thousands of years. This view has become the basis of ice core research. Many studies of modern climatology are based on this.
Peterson found that there was almost no lead in the atmosphere before 1923; Since then, the concentration of lead has been rising dangerously. Now, driving lead out of gasoline has become his lifelong pursuit. To this end, he often criticizes the lead industry and its interest groups, and his words are often fierce.
This proved to be a cruel struggle. Siyi company is a powerful company in the world, with many friends on it. (Its directors include Justice lewis powell of the Supreme Court and Gilbert grosvenor of the American Geographic Society. ) Peterson suddenly found that research funds were either recovered or difficult to obtain. American petroleum institute cancelled his contract, and so did the US Department of Public Health, which remains a neutral government agency.
Peterson has become an increasingly unfavorable person to this unit. Leading industry officials keep pressing the board members of Caltech to shut up or fire him. Jamie Lincoln Kidman wrote in National magazine in 2000 that Four B is said to be willing to provide a professor's lecture fee to California Institute of Technology for free, "if Peterson can pack his bags and leave". Paradoxically, an American research committee was appointed to investigate the risk of lead poisoning in the atmosphere, but he was excluded, although he was undoubtedly the main expert on lead poisoning in the atmosphere in the United States at this time.
Fortunately, Peterson never wavered. Thanks to his efforts, he finally put forward the Clean Air Act of 1970 and stopped selling all leaded gasoline in the United States in 1986. The lead concentration in American blood dropped by 80% almost immediately. However, because lead is a hard substance to eliminate, the blood lead concentration of every living American today is still about 625 times higher than that of people a century ago. The content of lead in the atmosphere is still increasing at a rate of about 654.38+million tons per year, and it is completely legal, mainly from mining, smelting and industrial activities. The United States also banned the addition of lead to household paints, as McGland said, "44 years later than most European countries." Considering the amazing toxicity of lead, it is incredible that the United States did not stop using lead solder in canned food until 1993.
As for Sisi Lee Company, although General Motors, Mobil Oil Company and DuPont Company have no shares in the company, they are still developing. (1962, they sold their shares to Almar Paper Company. According to McGrane, as of February 5438+0, 2006, Four B still insisted that "research shows that leaded gasoline does not pose a threat to human health or the environment". On its website, the company's history makes no mention of lead-nor George Midgley-but simply mentions that the original product contained "some kind of chemical mixture".
Leaded gasoline will no longer be produced, but according to the company statement of 200 1, the sales of tetraethyl lead in 2000 still reached 2,565.438 million US dollars (with a total sales of 795 million US dollars), slightly higher than 2,465.438 million US dollars in 1999, but lower than 1998 US dollars. In the report, the company said that it was determined to "maximize the cash income brought by tetraethyl lead, despite the decline in global use". Tetraethyl lead company sells tetraethyl lead all over the world through an agreement with Octell United Company in Britain.
As for another scourge left by George Midgley, 1974 The United States banned the use of chlorofluorocarbons (CFCs), but it was just a stubborn little devil. This kind of thing (such as deodorant or hair gel) that was previously released into the atmosphere is almost certainly still there, and ozone will be swallowed up in the west long after you and I die. To make matters worse, we still emit a lot of chlorofluorocarbons into the atmosphere every year. Wayne Bedell said that there are still more than 27 million kilograms of this kind of thing on the market every year, worth $654.38+05 billion. So, who is producing CFCs? It's us-that is to say, many overseas factories of big companies are still producing this product. Third world countries will not ban it until 20 10.
Claire Patterson died in 1995. He didn't win the Nobel Prize for his achievements. Geologists are never qualified. What is even more puzzling is that despite his perseverance, selfless dedication and increasing achievements over the past half century, he has not gained much fame or even received much attention. We have reason to believe that he is the most influential geologist in the 20th century. However, who has heard of Claire Patterson? Most geology textbooks don't mention his name. Two best-selling books about the history of the earth published recently even misspelled his name. At the beginning of 200 1, someone wrote a book review on one of the books in Nature. As a result, he made another mistake and unexpectedly thought that Peterson was a woman.
Anyway, thanks to Claire Patterson's work, by 1953, the earth finally had an age acceptable to everyone. The only problem now is that it is older than the world around it.