This 60-minute video documentary explores the conditions on Earth that allow for intelligent life and also make it a str | dG1fOG9odUczVmpfNDg
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Short filmTranscript
00:00 [MUSIC PLAYING]
00:28 A lot of things went right on Earth
00:30 to have yielded complex life, absolutely.
00:33 The number of factors that have been postulated has grown.
00:39 Currently, the typical number you would see in a typical list
00:42 would have something like 20.
00:46 We find that we need to be at the right location
00:48 in the galaxy, that we're inside the circumstellar habitable
00:51 zone of a star, that we're in a planetary system
00:54 with giant planets that can shield the inner planets
00:56 from too many comet impacts, that we're
00:58 orbiting the right kind of star that's not too cool or not
01:01 too hot, that we're on a planet that
01:04 has a moon that can stabilize the tilt of its axis,
01:08 that we're on a planet that's a terrestrial planet, a planet
01:11 that has a crust that's just thick enough that it can
01:14 maintain plate tectonic activity,
01:16 that it has enough heat in its interior
01:18 that it's still circulating its liquid iron cores
01:20 so it can generate a magnetic field,
01:22 that it has an atmosphere that has enough oxygen to allow
01:26 for complex organisms to survive,
01:29 that it has enough water and enough continents
01:32 to allow for the diversity of life or an active biosphere
01:35 that you need to support complex creatures such as ourselves.
01:39 All these factors have to be met at one place and time
01:43 in the galaxy if you're going to have a planet as
01:46 habitable as the Earth, which you
01:48 need for complex and even technological life.
01:52 In an attempt to estimate the probability of attaining
01:55 this combination of factors simultaneously,
01:59 some researchers have developed equations
02:01 assigning a conservative 1 in 10 value
02:05 to each factor deemed necessary for advanced life.
02:09 If every element has to be there at the same time,
02:12 you have to multiply the probabilities.
02:14 And that's what makes the probability at the end so
02:16 small.
02:16 You've got 10% of this and 10% of that.
02:19 And these things rapidly multiply
02:21 to exceedingly small numbers, numbers
02:23 on the order of 10 to minus 15, which is 1/1000th of 1/1 trillion.
02:27 And it's a number like that that you
02:29 have to compare to the 100 billion stars that
02:31 are in the galaxy.
02:32 100 billion is a very large number,
02:34 but 1/1000th of a trillion is much, much smaller.
02:38 On their face value, these probabilities are speaking.
02:42 What they're telling us is this can't happen,
02:45 or this is very unlikely to happen in the galaxy.
02:48 And that's where the evidence is pushing us.
02:51 There are many probabilistic resources in the galaxy,
02:54 but on the other side of the coin
02:56 are all these factors that you need.
02:59 You have to get just right in order
03:01 to have just one habitable planet like the Earth.
03:04 And that leads me to conclude that, yes, we're
03:07 rare in the galaxy.
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