揽瓜阁俱乐部第四期 Day3 2021.01.20
【自然科学-科技】 What quantum computers reveal about innovation：Venture capital is often the last guest to arrive at the party (The Economist - 706字 短精读）
It is hard to choose one moment as marking the birth of a technology. But by one common reckoning, quantum computing will be 40 next year. In 1981 Richard Feynman, an American physicist, spoke at a computing conference, observing that “Nature isn’t classical, dammit, and if you want to make a simulation of nature, you’d better make it quantum mechanical, and by golly it’s a wonderful problem, because it doesn’t look so easy.”
Entering middle age, quantum computing is at last becoming a commercial proposition (see article). Until recently the consensus was that practical applications would have to wait for large, stable machines, probably at least a decade away. Not everyone agrees. Venture capital is beginning to flow into companies built around quantum computers, as investors make a bold—possibly foolhardy—bet that even the limited, error-prone, unstable machines that make up the state-of-the-art today may prove commercially useful.
If those bets pay off, it would be good news, and not just for investors. Quantum computers can perform some sorts of mathematics far faster than any classical machine. Building them could open up entirely new vistas. They may, for instance, revolutionise chemistry. Most reactions are too complex for existing computers to simulate exactly, blunting researchers’ precision. Quantum machines could cut through the mathematical tangle, with applications in materials science, drugmaking, batteries and more. Their facility with optimisation problems, which are likewise a struggle for non-quantum machines, could be a boon for logistics, finance and artificial intelligence.
The field’s progress is interesting for another reason. Quantum computing offers a worked example of how complicated technologies develop in industrial societies. The chief lesson is to attend to every part of the process. The frenzy of innovation around classical computing, concentrated in Silicon Valley, has focused attention on the world of startups, venture capital and ipos. But these are things that happen late in a technology’s development, when swift commercial returns are, if not certain, then at least plausible. As Mariana Mazzucato, an Italian-American economist, has argued, the biggest risks are taken earlier, when it is unclear whether a technology will work at all.
The state can be one such risk-taker. The first step in building a quantum computer was to conduct plenty of abstruse mathematics on university blackboards. Collectively, governments, including those of America, Britain, China and Germany, have thrown billions of dollars at funding quantum research.
Other early work was done in the sorts of big, boring companies in which no self-respecting disrupter would be seen dead. The first useful quantum algorithm was discovered in 1994 at Bell Labs, which began life as the research division of America’s telephone monopoly. Another early pioneer was ibm, which also has a buttoned-up reputation—but whose researchers have, over the years, earned six Nobel prizes. Today Google and Microsoft are playing a big role in developing quantum technologies.
The trick for such super-early-stage investors is to know when to stick with a risky prospect and when to call it quits. Good venture capitalists are ruthless about culling underperforming bets and focusing on those that seem to be paying off. Their proximity to markets makes such judgments easier. But governments—which are, after all, spending public money—should strive for the same outlook. If the state is to back technologies that are too risky for other investors, then a high rate of failure is both inevitable and desirable.
There are other lessons, too. Quantum computing has come as far as it has on the backs of thousands of mathematicians, experimental physicists and engineers. That is a reminder of the limits of “great man” theories of innovation, exemplified by the cult of Steve Jobs, a founder of Apple. The popular image of innovation as a “pipeline”, with a stream of individual technologies proceeding smoothly from ideas to products, is likewise too neat. Progress in quantum computing depends on progress in dozens of other fields, from lasers to cryogenics.
None of that is to deny the importance of the people who run the last few miles, taking nascent technologies and trying to spin out profitable businesses. But those who want to see more of that success should keep in mind that a great deal of less celebrated, less glamorous work must come first.
Source: The Economist
【自然科学-气候】 Mini ice age (WSY - 485字 短阅读)
The Next Ice Age But first things first. Isn't the earth actually warming?
Indeed it is, says Joyce. In his cluttered office, full of soft light from the foggy Cape Cod morning, he explains how such warming could actually be the surprising culprit of the next mini-ice age. The paradox is a result of the appearance over the past 30 years in the North Atlantic of huge rivers of freshwater—the equivalent of a 10-foot-thick layer—mixed into the salty sea. No one is certain where the fresh torrents are coming from, but a prime suspect is melting Arctic ice, caused by a buildup of carbon dioxide in the atmosphere that traps solar energy.
The freshwater trend is major news in ocean-science circles. Bob Dickson, a British oceanographer who sounded an alarm at a February conference in Honolulu, has termed the drop in salinity and temperature in the Labrador Sea—a body of water between northeastern Canada and Greenland that adjoins the Atlantic—"arguably the largest full-depth changes observed in the modern instrumental oceanographic record."
The trend could cause a little ice age by subverting the northern penetration of Gulf Stream waters. Normally, the Gulf Stream, laden with heat soaked up in the tropics, meanders up the east coasts of the United States and Canada. As it flows northward, the stream surrenders heat to the air. Because the prevailing North Atlantic winds blow eastward, a lot of the heat wafts to Europe. That's why many scientists believe winter temperatures on the Continent are as much as 36 degrees Fahrenheit warmer than those in North America at the same latitude. Frigid Boston, for example, lies at almost precisely the same latitude as balmy Rome. And some scientists say the heat also warms Americans and Canadians. "It's a real mistake to think of this solely as a European phenomenon," says Joyce.
Having given up its heat to the air, the now-cooler water becomes denser and sinks into the North Atlantic by a mile or more in a process oceanographers call thermohaline circulation. This massive column of cascading cold is the main engine powering a deepwater current called the Great Ocean Conveyor that snakes through all the world's oceans. But as the North Atlantic fills with freshwater, it grows less dense, making the waters carried northward by the Gulf Stream less able to sink. The new mass of relatively fresh water sits on top of the ocean like a big thermal blanket, threatening the thermohaline circulation. That in turn could make the Gulf Stream slow or veer southward.
At some point, the whole system could simply shut down, and do so quickly. "There is increasing evidence that we are getting closer to a transition point, from which we can jump to a new state. Small changes, such as a couple of years of heavy precipitation or melting ice at high latitudes, could yield a big response," says Joyce.
Source: WSY
【自然科学-环境】 Undersea Earthquakes Reveal Sound Warming Info (科学美国人-3分17秒 精听)
先做听力再核对原文哦~
To us humans, climate change feels like something that’s happening to the atmosphere. But most of the action is actually at sea—about 90 percent of the heat that gets trapped by greenhouse gases is absorbed by the ocean.
“So it’s really important to track that energy in the climate system and track the warming of the ocean.”
Jörn Callies, an oceanographer at Caltech.
Of course, the ocean is really big, and taking its temperature is hard. Satellites give information about the surface, and scientists have launched drifting devices that measure conditions in the upper mile of water. But researchers still struggle to collect data from the deep ocean, and to detect the long-term trends underlying day-to-day variations in temperature.
Now, however, scientists have developed a new technique that allows them to measure temperature changes across entire ocean basins. The idea dates back to the 1970s, when researchers first proposed using sound waves to study ocean warming—because the speed of sound through water depends on the physical properties of that water, which are related to temperature.
“And roughly, if we warm up the ocean temperature by one degree, the sound speed change—it would be four meters per second. And this is a very sensitive change.”
Wenbo Wu, a seismologist also at Caltech, who led the study. That one degree he mentioned is a Celsius degree.
Researchers originally proposed using artificial sound sources, but that notion got nixed because of concerns about the impacts on marine animals. In the new study, however, Wu, Callies and their colleagues show they can use the sounds produced by earthquakes instead.
In an earthquake, some vibrations bounce off the seafloor and turn into sound waves that get picked up by seismometers and underwater microphones.
The researchers looked at the travel times of these sound waves for 2,000 pairs of earthquakes that occurred in the East Indian Ocean between 2005 and 2016. Each earthquake pair happened in the same place but at different times, allowing the researchers to measure how much the sound waves sped up.
The analysis revealed that the waves traveled a few tenths of a second faster in more recent quakes than in older ones—a difference that translates to a warming trend of 0.04 degrees Celsius per decade.
Four one-hundredths of a degree may not sound like a lot, but it represents a huge amount of heat—considering it’s the change in a body of water almost 2,000 miles wide and several miles deep.
The warming is also substantially higher than the rate reported in previous studies, although Callies says not to put too much stock in those discrepancies.
“We don’t know whether that is the general finding—whether that only occurs here in this region at this time—or whether that is something we’ll find in other regions as well. We just don’t have the data yet.”
The study is in the journal Science.
Callies and Wu say that this approach may even enable scientists to gauge historical temperature changes by studying data from much older earthquakes. In other words, you could say that the method is sound.
Source: Scientific American
【笔记格式要求】 同学们任选 2 片文章精读/精听并进行笔记打卡
精读笔记格式要求： 1.总结文章中心大意 2.总结分论点或每段段落大意 3.摘抄印象深刻或者觉得优美的句子 4.总结文章中的生词 5.记录阅读时间、总结时间、总时间
精听笔记格式要求： 1.逐句听写整篇文章 2.对照原文修改听写稿，标记出错原因 3.总结文章中心大意 4.总结精听过程中的生词 5.记录听写时间、总结时间、总时间
这里也给大家三点学习小建议哦~ 精读：如遇到读不懂的复杂句，建议找出句子主干，分析句子成分，也可以尝试翻译句子来帮助理解~ 精听：建议每句不要反复纠结听，如果听 5 遍都没听出来，那就跳过，等完成后再回听总结原因，时间宝贵，不要过于执着哦~
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发表于 2021-1-19 22:46:34
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