【推荐3】Terrible noises, drunk people, dangerous animals — any number of things can go wrong during a live news report.

News reporters are famous for their ability to keep going. And NBC Nightly News host Brian Williams is a fine example of that. He was reporting on a bankruptcy (破产) case when a fire alarm suddenly started ringing. It was followed shortly afterwards by an announcement. “You’ll have to forgive us,” Brian explained very calmly, “we have a fire alarm going on in here.”

An ability to keep a straight face is another important skill. A reporter from Channel 9 news in Australia was reporting on a murder (谋杀) case when a huge white bird walked across the back of the screen. The bird then appeared right as the reporter said the word “burden” (which sounds similar to the word “bird”). In an interview after the incident, the reporter explained how he saw the bird, but felt that he couldn’t laugh because of the seriousness of the story. “It was a bit of a surprise at the time,” he added.

But not all reporters have such abilities. During a report on strange pets, a lizard (蜥蜴) suddenly jumped onto the suit of a Channel 5 news reporter. “Get this thing off me,” the reporter shouted, as he crazily tried to brush it off. Finally, the reporter managed to regain his calmness.

Australian TV reporter Steve Jacobs was involved in a similar incident. Soon after starting an off-camera weather report, the sound of laughter could be heard. Suddenly the camera showed the reporter standing against a rock in a zoo as an angry bird attacked his backside. Finally, a zookeeper managed to attract the bird away, but the weatherman still shouted, “I’m going to be mentally scarred (精神上伤痕累累)!”

【推荐2】Satellite imagery like Google Earth makes it easy for ecologists halfway around the world to check up on tropical forests—see illegal roads and logging (伐木), for example. But the information is limited.

“Satellite data often tells you what happens after it's happened.” Rhett Butler said, the founder of Mongabay. com, an environmental science news website. In a perspective piece in the journal Science, he and his colleagues write that sound recordings can supplement satellite data as another conservation tool.

You can actually set up alerts. So you can hear things like chainsaws (电锯) or gunshots in real time. So you can get put ahead of potential deforestation before it occurs. Small audio recorders, some of which are solar-powered and connecteded to cellphone grids for data upload, also give ecologists the ability to listen secretly on a jungle's biodiversity over time.

If you're in a primary forest, you'll tend to see all the frequencies of the soundscape occupied by different species. These are insects, birds, calling mammals, frogs things like that.”

As a comparison, here is a forest plot after selective logging---meaning some trees were cut, others left standing. “As you move into a more disturbed ecosystem, you'd start to see more gapsacross the frequencies of that soundscape.”

Certain insects dominate. And the diversity of calls declines as disturbance increases. While the human ear is perceptive (感知的), algorithms (运算法则) are a much more powerful tool to comb through thousands of hours of data, to get a richer picture of changing tropical biodiversity.

Nowadays, many industries---like cattle farming, palm oil, soybean and paper production are committing to zero deforestation goals, which can be hard to measure. But by coupling satellite data and camera traps with audio recordings, ecologists can keep their eyes-and ears-on what's going on in the jungle.

【推荐3】Back in 2015 my colleague Adam Frank of the University of Rochester and I were having lunch near Columbia University's campus in New York City. As at Fermi's lunch 65 years earlier, the conversation was about the nature of spacefaring species. And inspired by Fermi's mental calculation, we were trying to craft an investigative strategy that made the fewest possible unsubstantiated assumptions and that could be somehow tested or constrained with real data. At the center of this exercise was the simple thought that waves of exploration or settlement could come and go across the galaxy, with humans happening to come into being in one of the lonely periods.

This idea relates to Hart's original fact: that there is no evidence here on Earth today of extraterrestrial（外星的）explorers. But it goes further by asking whether we can obtain meaningful limits on galactic（星系的）life by constraining the exact length of time over which Earth might have gone unvisited. Perhaps long, long ago extraterrestrial explorers came and went. A number of scientists have, over the years, discussed the possibility of looking for artifacts that might have been left behind after such visitations of our solar system. The necessary scope of a complete search is hard to predict, but the situation on Earth alone turns out to be a bit more manageable. In 2018 another of my colleagues, Gavin Schmidt of NASA's Goddard Institute for Space Studies, together with Adam Frank, produced a critical assessment of whether we could even tell if there had been an earlier industrial civilization on our planet.

As fantastic as it may seem, Schmidt and Frank argue—as do most planetary scientists—that it is actually very easy for time to erase essentially all signs of technological life on Earth. The only real evidence after a million or more years would boil down to isotopic or chemical stratigraphic anomalies—odd features such as synthetic molecules, plastics or radioactive fallout. Fossil remains and other paleontological markers are so rare that they might not tell us anything in this case.

Indeed, modern human urbanization covers only on order of about 1 percent of the planetary surface, providing a very small target area for any paleontologists（古生物学家）in the distant future. Schmidt and Frank also conclude that nobody has yet performed the necessary experiments to look exhaustively for such non-natural signatures on Earth. The bottom line is, if an industrial civilization on the scale of our own had existed a few million years ago, we might not know about it. That absolutely does not mean one existed; it indicates only that the possibility cannot be completely eliminated.