2020수능특강 영어 22강 본문

22강

1

The people who came before you invented science because your natural way of understanding and explaining what you experience is terrible. When you have zero evidence, every assumption is basically equal. You prefer to see causes rather than effects, signals in the noise, patterns in the randomness. You prefer easy‑to‑understand stories, and thus turn everything in life into a narrative so that complicated problems become easy. Scientists work to remove the narrative, to boil it away, leaving behind only the raw facts. Those data sit there, naked and exposed, so they can be reflected upon and rearranged by each new visitor. Scientists and laypeople will conjure up new stories using the data, and they will argue, but the data will not budge. They may not even make sense for a hundred years or more, but thanks to the scientific method, the stories, full of biases and fallacies, will crash against the facts and recede into history.

 

2

As the sun rises in the morning, sunlight warms the ground, and the ground warms the air in contact with it by conduction. However, air is such a poor heat conductor that this process only takes place within a few centimeters of the ground. As the sun rises higher in the sky, the air in contact with the ground becomes even warmer, and there exists a thermal boundary separating the hot surface air from the slightly cooler air above. Given their random motion, some air molecules will cross this boundary: The “hot” molecules below bring greater kinetic energy to the cooler air; the “cool” molecules above bring a deficit of energy to the hot surface air. However, on a windless day, this form of heat exchange is slow, and a substantial temperature difference usually exists just above the ground. This explains why runners on a clear, windless, summer afternoon may experience air temperatures of over 50°C (122°F) at their feet and only 32°C (90°F) at their waist.

 

3

The idea of using cold temperatures to extend the shelf life of food has been known for centuries. The great Francis Bacon, the early seventeenth‑century polymath rather than the twentieth‑century painter, is generally credited with inventing the frozen chicken. It was not all he did, but certainly the only thing relevant to refrigeration. In the early spring of 1626, while on the way to Highgate in North London, for reasons unrecorded, Bacon decided to buy a chicken whose organs had been removed and stuff it with snow, thus demonstrating that refrigeration was a remarkable way of keeping food fresh for longer. Unfortunately, as the whole escapade was a spontaneous experiment, Bacon must have been unsuitably dressed for the snow. He caught a chill, which became pneumonia, and he died shortly thereafter while still at Highgate. He died a martyr to his science and sadly history does not record the fate of the world’s first oven‑ready frozen chicken.

 

4

Genetic diversity, the heritable diversity among individuals and populations within species, provides the basis for evolution. Over millions of years it has enabled forests and trees to adapt to changing conditions. Some tree species have been domesticated, but the management of forest genetic resources mainly involves tree populations that have undergone little selection by humans. The vast majority of forest genetic diversity remains undescribed, especially in the tropics. Estimates of the number of tree species vary from 80,000 to 100,000, but fewer than 500 have been studied in any depth. Until recently, studies of forest tree genetic resources have concentrated on the few species regarded as the most suitable for domestication for use in plantations and agroforestry systems to produce wood, fibre or fuel. The present and future potential of most tree species to adapt in response to novel climatic conditions or for genetic improvement for human use remains largely unknown.