pale blue dot -carl sagan-第7节
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of other stars； absence of evidence had been considered evidence of absence。
Today we have firm evidence for at least three planets orbiting an extremely dense star； the pulsar designated B1257＋12； about which I'll say more later。 And we've found； for more than half the stars with masses like the Sun's； that early in their careers they're surrounded by great disks of gas aid dust out of which planets seem to form。 Other planetary systems now look to be a cosmic monplace； maybe even worlds something like the Earth。 We should be able； in the next few decades； to inventory at least the larger planets； if they exist； of hundreds of nearby stars。
Well； if our position in space doesn't reveal our special role； our position in time does： We've been in the Universe since The Beginning （give or take a few days）。 We've been given special responsibilities by the Creator。 It once seemed very reasonable to think of the Universe as beginning just a little before our collective memory is obscured by the passage of time and the illiteracy of our ancestors。 Generally speaking； that's hundreds or thousands of years ago。 Religions that purport to describe the origin of the Universe often specify—implicitly or explicitly—a date of origin of roughly such vintage； a birthday for the world。
If you add up all the 〃begats〃 in Genesis； for example； you get an age for the Earth： 6；000 years old； plus or minus a little。 The universe is said to be exactly as old as the Earth。 This is still the standard of Jewish； Christian； and Moslem fundamentalists and is clearly reflected in the Jewish calendar。
But so young a Universe raises an awkward question： How is it that there are astronomical objects more than 6；000 light…years away？ It takes light a year to travel a light…year； 10；000 years to travel 10；000 light…years； and so on。 When we look at the center of the Milky Way Galaxy； the light we see left its source 30；000 years ago。 The nearest spiral galaxy like our own； M31 in the constellation Andromeda； is 2 million light…years away； so we are seeing it as it was when the light from it set out on its long journey to Earth—2 million years ago。 And when we observe distant quasars 5 billion light…years away； we are seeing them as they were 5 billion years ago； before the Earth was formed。 （They are； almost certainly； very different today。）
If； despite this； we were to accept the literal truth of such religious books； how could we reconcile the data？ The only plausible conclusion； I think； is that God recently made all the photons of light arriving on the Earth in such a coherent format as to mislead generations of astronomers into the misapprehension that there are such things as galaxies and quasars； and intentionally driving them to the spurious conclusion that the Universe is vast and old。 This is such a malevolent theology I still have difficulty believing that anyone； no matter how devoted to the divine inspiration of any religious book； could seriously entertain it。
Beyond this； the radioactive dating of rocks； the abundance of impact craters on many worlds； the evolution of the stars； and the expansion of the Universe each provides pelling and independent evidence that our Universe is many billions of years old—despite the confident assertions of revered theologians that a world so old directly contradicts the word of God； and that at any rate information on the antiquity of the world is inaccessible except to faith。 These lines of evidence； as well； would have to be manufactured by a deceptive and malicious deity—unless the world is much older than the literalists in the Judeo…Christian…Islamic religion suppose。 Of course； no such problem arises for those many religious people who treat the Bible and the Qur'an as historical and moral guides and great literature； but who recognize that the perspective of these scriptures on the natural world reflects the rudimentary science of the time in which they were written。
Ages rolled by before the Earth began。 More ages will run their course before it is destroyed。 A distinction needs to be drawn between how old the Earth is （around 4。5 billion years） and how old the Universe is （about 15 billion years since the Big Bang）。 The immense interval of time between the origin of the Universe and our epoch was two…thirds over before the Earth came to be。 Some stars and planetary systems are billions of years younger； others billions of years older。 But in Genesis； chapter 1； verse 1； the Universe and the Earth are created on the same day。 The Hindu…Buddhist…Jain religion tends not to confound the two events。
As for humans； we're lateers。 We appear in the last instant of cosmic time。 The history of the Universe till now was 99。998 percent over before our species arrived on the scene。 In that vast sweep of aeons； we could not have assumed any special responsibilities for our planet； or life； or anything else。 We were not here。
Well； if we can't find anything special about our position or our epoch； maybe there's something special about our motion。 Newton and all the other great classical physicists held that the velocity of the Earth in space constituted a 〃privileged frame of reference。〃 That's actually what it was called。 Albert Einstein； a keen critic of prejudice and privilege all his life； considered this 〃absolute〃 physics a remnant of an increasingly discredited Earth chauvinism。 It seemed to him that the laws of Nature must be the same no matter what the velocity or frame of reference of the observer。 With this as his starting point； he developed the Special Theory of Relativity。 Its consequences are bizarre； counter intuitive； and grossly contradict mon sense—but only at very high speeds。 Careful and repeated observations show that his justly celebrated theory is an accurate description of how the world is made。 Our monsense intuitions can be mistaken。 Our preferences don't count。 We do not live in a privileged reference frame。
One consequence of special relativity is time dilation—the slowing down of time as the observer approaches light speed。 You can still find claims that time dilation applies to watches and elementary particles—and； presumably； to circadian and other rhythms in plants； animals； and microbes—but not to human biological clocks。 Our species has been granted； it is suggested； special immunity from the laws of Nature； which must accordingly be able to distinguish deserving from undeserving collections of matter。 （In fact； the proof Einstein gave for special； relativity admits no such distinctions。） The idea of humans as exceptions to relativity seems another incarnation of the notion of special creation：
Well； even if our position； our epoch； our motion； and our world are not unique； maybe we are。 We're different from the other animals。 We're specially created。 The particular devotion of the Creator of the Universe is evident in us。 This position was passionately defended on religious and other grounds。 But in the middle nineteenth century Charles Darwin showed convincingly how one species can evolve into another by entirely natural processes； which e down to the heartless business of Nature saving the heredities that work and rejecting those that don't。 〃Man in his arrogance thinks himself a great work worthy ＇of＇ the interposition of a deity；〃 Darwin wrote telegraphically in his notebook。 〃More humble and I think truer to consider him created from animals。〃 The profound and intimate connections of humans with the other life forms； on Earth have been pellingly demonstrated in the late twentieth century by the new science of molecular biology。
IN EACH AGE the self…congratulatory chauvinisms are challenged in yet another arena of scientific debate—in this century； for example； in attempts to understand the nature of human sexuality； the existence of the unconscious mind； and the fact that many psychiatric illnesses and character 〃defects〃 have a molecular origin。 But also：
Well； even if we're closely related to some of the other animals； we're different—not just in degree； but in kind—on what really matters： reasoning； selfconsciousness； tool making； ethics； altruism； religion； language； nobility of character。 While humans； like all animals； have traits that set them apart—otherwise； how could we distinguish one species from another？—human uniqueness has been exaggerated； sometimes grossly so。 Chimps reason； are self…conscious； make tools； show devotion； and so on。 Chimps and humans have 99。6 percent of their active genes in mon。 （Ann Druyan and I run through the evidence in our book Shadows of Forgotten Ancestors。）
In popular culture； the very opposite position is also embraced； although it too is driven by human chauvinism （plus a failure of the imagination）： Children's stories and cartoons make animals dress in clothes； live in houses； use knives and forks； and speak。 The three bears sleep in beds。 The owl and the pussycat go to sea in a beautiful pea…green boat。 Dinosaur mothers cuddle their young。 Pelicans deliver the mail。 Dogs drive cars。 A worm catches a thief。 Pets have human names。 Dolls； nutcrackers； cups； and saucers dance and have opinions。 The dish runs away with the spoon。 In the Thomas the Tank Engine series； we even have anthropom
