万物简史 第35期:走进太阳系(13)

Still, statistically the probability that there are other thinking beings out there is good. Nobody knows how many stars there are in the Milky Wayestimates range from 100 billion or so to perhaps 400 billionand the Milky Way is just one of 140 billi

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What an interesting and exciting thought. We may be only one of millions of advanced civilizations. Unfortunately, space being spacious, the average distance between any two of these civilizations is reckoned to be at least two hundred light-years, w

万物简史 第34期:走进太阳系(12)

So that's your solar system. And what else is out there, beyond the solar system? Well, nothing and a great deal, depending on how you look at it. 这就是你所在的太阳系。太阳系之外还有别的什么？哎呀，也许什么也没有，也

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But let's pretend again that we have made it to the Oort cloud. The first thing you might notice is how very peaceful it is out here. We're a long way from anywhere nowso far from our own Sun that it's not even the brightest star in the sky. It is a

万物简史 第32期:走进太阳系(10)

Of course we have no prospect of such a journey. A trip of 240,000 miles to the Moon still represents a very big undertaking for us. A manned mission to Mars, called for by the first President Bush in a moment of passing giddiness, was quietly droppe

万物简史 第31期:走进太阳系(9)

So the solar system is really quite enormous. By the time we reach Pluto, we have come so far that the Sunour dear, warm, skin-tanning, life-giving Sunhas shrunk to the size of a pinhead. It is little more than a bright star. 所以，太阳系确实是

万物简史 第53期:埃文斯牧师的宇宙(17)

At this point, about 4.5 billion years ago, an object the size of Mars crashed into Earth, blowing out enough material to form a companion sphere, the Moon. Within weeks, it is thought, the flung material had reassembled itself into a single clump, a

万物简史 第54期:事物的测定(1)

PART II THE SIZE OF THE EARTH 第二部分 地球的大小 Nature and Nature's laws lay hid in night; 大自然和大自然的法则藏匿于黑夜之中； God said, Let Newton be! And all was light. 上帝说，让牛顿出世吧！于是世界一片

万物简史 第55期:事物的测定(2)

At one point the group had to suspend work for eight months while La Condamine rode off to Lima to sort out a problem with their permits. Eventually he and Bouguer stopped speaking and refused to work together. Everywhere the dwindling party went it

万物简史 第56期:事物的测定(3)

For all his achievements, however, Halley's greatest contribution to human knowledge may simply have been to take part in a modest scientific wager with two other worthies of his day: Robert Hooke, who is perhaps best remembered now as the first pers

万物简史 第58期:事物的测定(5)

For all his brilliance, real science accounted for only a part of his interests. At least half his working life was given over to alchemy and wayward religious pursuits. These were not mere dabblings but wholehearted devotions. He was a secret adhere

万物简史 第59期:事物的测定(6)

Quite what Halley expected to get from him when he made his unannounced visit in August 1684 we can only guess. But thanks to the later account of a Newton confidant, Abraham DeMoivre, we do have a record of one of science's most historic encounters:

万物简史 第60期:事物的测定(7)

Once in a great while, a few times in history, a human mind produces an observation so acute and unexpected that people can't quite decide which is the more amazingthe fact or the thinking of it. Principia was one of those moments. It made Newton ins

万物简史 第57期:事物的测定(4)

Newton was a decidedly odd figurebrilliant beyond measure, but solitary, joyless, prickly to the point of paranoia, famously distracted (upon swinging his feet out of bed in the morning he would reportedly sometimes sit for hours, immobilized by the

万物简史 第49期:埃文斯牧师的宇宙(13)

The reason we can be reasonably confident that such an event won't happen in our corner of the galaxy, Thorstensen said, is that it takes a particular kind of star to make a supernova in the first place. 索尔斯坦森说，有理由相信，这种事

万物简史 第46期:埃文斯牧师的宇宙(10)

Looking for supernovae is mostly a matter of not finding them. From 1980 to 1996 he averaged two discoveries a yearnot a huge payoff for hundreds of nights of peering and peering. Once he found three in fifteen days, but another time he went three ye

万物简史 第47期:埃文斯牧师的宇宙(11)

There's something satisfying, I think, Evans said, about the idea of light traveling for millions of years through space and just at the right moment as it reaches Earth someone looks at the right bit of sky and sees it. It just seems right that an e

万物简史 第48期:埃文斯牧师的宇宙(12)

The question that naturally occurs is What would it be like if a star exploded nearby? Our nearest stellar neighbor, as we have seen, is Alpha Centauri, 4.3 light-years away. I had imagined that if there were an explosion there we would have 4.3 year

万物简史 第50期:埃文斯牧师的宇宙(14)

Supernovae are significant to us in one other decidedly central way. Without them we wouldn't be here. You will recall the cosmological conundrum with which we ended the first chapterthat the Big Bang created lots of light gases but no heavy elements

万物简史 第51期:埃文斯牧师的宇宙(15)

It was he who coined the term Big Bang, in a moment of facetiousness, for a radio broadcast in 1952. He pointed out that nothing in our understanding of physics could account for why everything, gathered to a point, would suddenly and dramatically be