Calculating The Odds of Intelligent Alien Life - Jill Tarter

1,260,039 views ใƒป 2012-07-02

TED-Ed


ืื ื ืœื—ืฅ ืคืขืžื™ื™ื ืขืœ ื”ื›ืชื•ื‘ื™ื•ืช ื‘ืื ื’ืœื™ืช ืœืžื˜ื” ื›ื“ื™ ืœื”ืคืขื™ืœ ืืช ื”ืกืจื˜ื•ืŸ.

00:00
Transcriber: Ido Dekkers Reviewer: Ariana Bleau Lugo
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(Music)
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ืชืจื’ื•ื: Ido Dekkers ืขืจื™ื›ื”: Zeeva Livshitz
(ืžื•ื–ื™ืงื”)
00:14
The basic question is, does life exist beyond Earth?
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ื”ืฉืืœื” ื”ื‘ืกื™ืกื™ืช ื”ื™ื, ื”ืื ื—ื™ื™ื ืงื™ื™ืžื™ื ืžื—ื•ืฅ ืœื›ื“ื•ืจ ื”ืืจืฅ?
00:17
Scientists who are called astrobiologists
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ืžื“ืขื ื™ื ืฉื ืงืจืื™ื ืืกื˜ืจื•ื‘ื™ื•ืœื•ื’ื™ื
00:21
are trying to find that out right now.
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ืžื ืกื™ื ืœื”ื‘ื™ืŸ ืืช ื–ื” ืžืžืฉ ืขื›ืฉื™ื•.
00:23
Most astrobiologists are trying to figure out
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ืจื•ื‘ ื”ืืกื˜ืจื•ื‘ื™ื•ืœื•ื’ื™ื ืžื ืกื™ื ืœื”ื‘ื™ืŸ
00:25
if there's microbial life on Mars,
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ืื ื™ืฉ ื—ื™ื™ื ืžื™ืงืจื•ื‘ื™ืืœื™ื ืขืœ ืžืื“ื™ื,
00:27
or in the ocean under the frozen surface of Jupiter's moon Europa,
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ืื• ื‘ืื•ืงื™ื™ื ื•ืกื™ื ืžืชื—ืช ืœืคื ื™ื ื”ืงืคื•ืื™ื ืฉืœ ื™ืจื— ืฆื“ืง, ืื™ืจื•ืคื”,
00:32
or in the liquid hydrocarbon lakes
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ื”ื•ื ื‘ืื’ืžื™ ื”ืคื—ืžืžื ื™ื ื”ื ื•ื–ืœื™ื™ื
00:34
that we've found on Saturn's moon Titan.
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ืฉืžืฆืื ื• ืขืœ ื˜ื™ื˜ืืŸ, ื”ื™ืจื— ืฉืœ ืฉื‘ืชืื™.
00:37
But one group of astrobiologists works on SETI.
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ืื‘ืœ ืงื‘ื•ืฆื” ืื—ืช ืฉืœ ืืกื˜ืจื•ื‘ื™ื•ืœื•ื’ื™ื ืขื•ื‘ื“ืช ื‘ SETI.
00:40
SETI is the Search for Extraterrestrial Intelligence,
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SETI ื”ื•ื ื”ื—ื™ืคื•ืฉ ืื—ืจ ืชื‘ื•ื ื” ื—ื•ืฆื ื™ืช,
00:43
and SETI researchers are trying to detect some evidence
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ื•ืžื“ืขื ื™ SETI ืžื ืกื™ื ืœื’ืœื•ืช ืขื“ื•ื™ื•ืช
00:46
that intelligent creatures elsewhere
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ืฉื—ื™ื™ื ืชื‘ื•ื ื™ื™ื ื‘ืžืงื•ื ืื—ืจ
00:49
have used technology to build a transmitter of some sort.
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ื”ืฉืชืžืฉื• ื‘ื˜ื›ื ื•ืœื•ื’ื™ื” ืœื‘ื ื•ืช ืžืฉื“ืจ ืžืกื•ื’ ื›ืœืฉื”ื•.
00:53
But how likely is it
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ืื‘ืœ ืžื” ื”ืกื‘ื™ืจื•ืช
00:55
that they will manage to find a signal?
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ืฉื”ื ื™ืฆืœื™ื—ื• ืœืžืฆื•ื ืื•ืช?
00:58
There are certainly no guarantees when it comes to SETI,
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ืžืžืฉ ืื™ืŸ ื‘ื˜ื—ื•ื ื•ืช ื›ืฉื–ื” ื ื•ื’ืข ืœ SETI,
01:01
but something called the Drake equation,
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ืื‘ืœ ืžืฉื”ื• ืฉื ืงืจื ืžืฉื•ื•ืืช ื“ืจื™ื™ืง,
01:04
named after Frank Drake,
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ืฉื ืงืจืืช ืขืœ ืฉื ืคืจื ืง ื“ืจื™ื™ืง,
01:07
can help us organize our thinking
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ื™ื›ื•ืœื” ืœืขื–ื•ืจ ืœืืจื’ืŸ ืืช ื“ืจืš ื”ื—ืฉื™ื‘ื” ืฉืœื ื•
01:09
about what might be required
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ืขืœ ืžื” ื“ืจื•ืฉ
01:11
for successful detection.
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ืœื’ื™ืœื•ื™ ืžื•ืฆืœื—.
01:14
If you've dealt with equations before,
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ืื ื”ืชืขืกืงืชื ืขื ืžืฉื•ื•ืื•ืช ืงื•ื“ื ืœื›ืŸ,
01:16
then you probably expect
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ืื– ืืชื ื›ื ืจืื” ืžืฆืคื™ื
01:18
that there will be a solution to the equation,
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ืฉื™ื”ื™ื” ืคื™ืชืจื•ืŸ ืœืžืฉื•ื•ืื”,
01:20
a right answer.
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ืชืฉื•ื‘ื” ื ื›ื•ื ื”.
01:22
The Drake equation, however, is different,
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ืžืฉื•ื•ืืช ื“ืจื™ื™ืง, ืขื ื–ืืช, ืฉื•ื ื”,
01:25
because there are so many unknowns.
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ืžืคื ื™ ืฉื™ืฉ ื›ืœ ื›ืš ื”ืจื‘ื” ืžืฉืชื ื™ื ืœื ื™ื“ื•ืขื™ื.
01:27
It has no right answer.
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ืื™ืŸ ืœื” ืชืฉื•ื‘ื” ื ื›ื•ื ื”.
01:30
As we learn more about our universe
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ื›ืฉืื ื—ื ื• ืœื•ืžื“ื™ื ื™ื•ืชืจ ืขืœ ื”ื™ืงื•ื
01:32
and our place within it,
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ื•ื”ืžืงื•ื ืฉืœื ื• ื‘ื•,
01:34
some of the unknowns get better known,
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ื›ืžื” ืžื”ืžืฉืชื ื™ื ื ื”ืคื›ื™ื ืœื™ื•ืชืจ ื™ื“ื•ืขื™ื,
01:37
and we can estimate an answer a bit better.
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ื•ืื ื—ื ื• ื™ื›ื•ืœื™ื ืœื”ืขืจื™ืš ืชืฉื•ื‘ื” ืžืขื˜ ื˜ื•ื‘ ื™ื•ืชืจ.
01:40
But there won't be a definite answer to the Drake equation
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ืื‘ืœ ืœื ืชื”ื™ื” ืชืฉื•ื‘ื” ื—ื“ ืžืฉืžืขื™ืช ืœืžืฉื•ื•ืืช ื“ืจื™ื™ืง
01:43
until SETI succeeds
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ืขื“ ืฉ SETI ื™ืฆืœื™ื—
01:46
or something else proves that
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ืื• ืฉืžืฉื”ื• ืื—ืจ ื™ื•ื›ื™ื—
01:48
Earthlings are the only intelligent species in our portion of the cosmos.
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ืฉืื ืฉื™ ื›ื“ื•ืจ ื”ืืจืฅ ื”ื ื”ืชื‘ื•ื ื” ื”ื™ื—ื™ื“ื” ื‘ื—ืœืง ืฉืœื ื• ืฉืœ ื”ื™ืงื•ื.
01:52
In the meantime,
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ื‘ื™ื ืชื™ื™ื,
01:53
it is really useful to consider the unknowns.
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ื–ื” ืžืžืฉ ืžื•ืขื™ืœ ืœื—ืฉื•ื‘ ืขืœ ื”ืžืฉืชื ื™ื.
01:56
The Drake equation attempts to estimate
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ืžืฉื•ื•ืืช ื“ืจื™ื™ืง ืžื ืกื” ืœื”ืขืจื™ืš
01:59
the number of technological civilizations
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ืืช ืžืกืคืจ ื”ืชืจื‘ื•ื™ื•ืช ื”ื˜ื›ื ื•ืœื•ื’ื™ื•ืช
02:02
in the Milky Way Galaxy -- we call that N --
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ื‘ื’ืœืงืกื™ื™ืช ืฉื‘ื™ืœ ื”ื—ืœื‘ - ืื ื—ื ื• ืงื•ืจืื™ื ืœื–ื” N --
02:05
with whom we could make contact,
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ืขื ืžื™ ืฉื ื•ื›ืœ ืœื™ืฆื•ืจ ืื™ืชื• ืงืฉืจ,
02:07
and it's usually written as:
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ื•ื–ื” ื‘ื“ืจืš ื›ืœืœ ื›ืชื•ื‘ ื›ืš:
02:10
N equals R-star
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N ืฉื•ื•ื” ืœR-ื›ื•ื›ื‘ื™ืช
02:13
multiplied by f-sub-p
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ื›ืคื•ืœ p ืฉืœ f
02:17
multiplied by n-sub-e
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ื›ืคื•ืœ e ืฉืœ n
02:20
multiplied by f-sub-l
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ื›ืคื•ืœ l ืฉืœ f
02:24
multiplied by f-sub-i
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ื›ืคื•ืœ i ืฉืœ f
02:27
multiplied by f-sub-c
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ื›ืคื•ืœ c ืฉืœ f
02:30
and lastly, multiplied by capital L.
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ื•ืœื‘ืกื•ืฃ, ื›ืคื•ืœ L ื’ื“ื•ืœื”.
02:35
All those factors multiplied together
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ื›ืœ ื”ื’ื•ืจืžื™ื ื”ืืœื” ืžื•ื›ืคืœื™ื ื™ื—ื“
02:37
help to estimate the number
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ืขื•ื–ืจื™ื ืœื”ืขืจื™ืš ืืช ืžืกืคืจ
02:39
of technological civilizations
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ื”ืชืจื‘ื•ื™ื•ืช ื”ื˜ื›ื ื•ืœื•ื’ื™ื•ืช
02:41
that we might be able to detect right now.
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ืฉืื•ืœื™ ื ื”ื™ื” ืžืกื•ื’ืœื™ื ืœื’ืœื•ืช ืขื›ืฉื™ื•.
02:44
R-star is the rate at which
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R-ื›ื•ื›ื‘ื™ืช ื”ื•ื ื”ืงืฆื‘ ื‘ื•
02:47
stars have been born in the Milky Way Galaxy
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ื›ื•ื›ื‘ื™ื ื ื•ืœื“ื• ื‘ื’ืœืงืกื™ืช ืฉื‘ื™ืœ ื”ื—ืœื‘
02:50
over the last few billion years,
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ื‘ืžืฉืš ืžืกืคืจ ืžื™ืœื™ืืจื“ื™ ื”ืฉื ื™ื ื”ืื—ืจื•ื ื•ืช,
02:52
so it's a number that is stars per year.
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ืื– ื–ื” ืžืกืคืจ ื”ื›ื•ื›ื‘ื™ื ื‘ืฉื ื”.
02:55
Our galaxy is 10 billion years old,
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ื”ื’ืœืงืกื™ื” ืฉืœื ื• ื‘ืช 10 ืžื™ืœื™ืืจื“ ืฉื ื™ื,
02:57
and early in its history stars formed at a different rate.
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ื•ื‘ืชื—ื™ืœืช ื”ื”ืกื˜ื•ืจื™ื” ืฉืœื” ื›ื•ื›ื‘ื™ื ื ื•ืฆืจื• ื‘ืงืฆื‘ ืฉื•ื ื”.
03:01
All of the f-factors are fractions.
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ื•ื›ืœ ืžืฉืชื ื™ ื” f ื”ื ืฉื‘ืจื™ื.
03:04
Each one must be less than or equal to one.
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ื›ืœ ืื—ื“ ืฆืจื™ืš ืœื”ื™ื•ืช ืคื—ื•ืช ืื• ืฉื•ื•ื” ืœืื—ื“.
03:08
F-sub-p is the fraction of stars that have planets.
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p ืฉืœ f ื”ื•ื ื”ืฉื‘ืจ ืฉืœ ื”ื›ื•ื›ื‘ื™ื ืฉื™ืฉ ืœื”ื ืคืœื ื˜ื•ืช.
03:11
N-sub-e
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e ืฉืœ n
03:13
is the average number of habitable planets
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ื”ื•ื ื”ืžืกืคืจ ื”ืžืžื•ืฆืข ืฉืœ ืคืœื ื˜ื•ืช ื ื™ืชื ื•ืช ืœื™ืฉื•ื‘
03:17
in any planetary system.
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ื‘ื›ืœ ืžืขืจื›ืช ืคืœื ื˜ืจื™ืช.
03:19
F-sub-l
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l ืฉืœ f
03:20
is the fraction of planets on which life actually begins
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ื”ื•ื ื”ืฉื‘ืจ ืฉืœ ืคืœื ื˜ื•ืช ื‘ื”ื ื—ื™ื™ื ื‘ืืžืช ืžืชื—ื™ืœื™ื
03:23
and f-sub-i is the fraction of all those life forms
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ื• i ืฉืœ f ื”ื•ื ื”ืฉื‘ืจ ืฉืœ ื›ืœ ืื•ืชืŸ ืฆื•ืจื•ืช ื—ื™ื™ื
03:27
that develop intelligence.
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ืฉืžืคืชื—ื•ืช ืชื‘ื•ื ื”.
03:29
F-sub-c is the fraction of intelligent life
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c ืฉืœ f ื”ื•ื ื”ืฉื‘ืจ ื›ืœ ื—ื™ื™ื ืชื‘ื•ื ื™ื™ื
03:32
that develops a civilization
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ืฉืžืคืชื—ื™ื ืชืจื‘ื•ืช
03:34
that decides to use some sort of transmitting technology.
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ืฉืžื—ืœื™ื˜ื” ืœื”ืฉืชืžืฉ ื‘ืกื•ื’ ื›ืœืฉื”ื• ืฉืœ ื˜ื›ื ื•ืœื•ื’ื™ื” ืฉื™ื“ื•ืจ.
03:38
And finally, L --
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ื•ืœื‘ืกื•ืฃ, L --
03:40
the longevity factor.
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ืžืงื“ื ื”ืืจื™ื›ื•ืช.
03:42
On average, how many years
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ื‘ืžืžื•ืฆืข, ื›ืžื” ืฉื ื™ื
03:44
do those transmitters continue to operate?
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ื”ืžืฉื“ืจื™ื ื”ืืœื” ืžืžืฉื™ื›ื™ื ืœืคืขื•ืœ?
03:47
Astronomers are now almost able
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ืืกื˜ืจื•ื ื•ืžื™ื ืขื›ืฉื™ื• ื›ืžืขื˜ ืžืกื•ื’ืœื™ื
03:50
to tell us what the product of the first three terms is.
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ืœื”ื’ื™ื“ ืœื ื• ืžื” ื”ืชื•ืฆืจ ืฉืœ ืฉืœื•ืฉืช ื”ืชื ืื™ื ื”ืจืืฉื•ื ื™ื.
03:54
We're now finding exoplanets almost everywhere.
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ืื ื—ื ื• ืขื›ืฉื™ื• ืžื•ืฆืื™ื ืคืœื ื˜ื•ืช ื›ืžืขื˜ ื‘ืขืœ ืžืงื•ื.
03:58
The fractions dealing with life and intelligence
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ื”ืฉื‘ืจื™ื ืฉืžื˜ืคืœื™ื ื‘ื—ื™ื™ื ื•ืชื‘ื•ื ื”
04:01
and technological civilizations
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ื•ืชืจื‘ื•ื™ื•ืช ืชื‘ื•ื ื™ื•ืช
04:03
are ones that many, many experts ponder,
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ื”ื ืืœื” ืฉืžื•ืžื—ื™ื ืจื‘ื™ื ืžืื•ื“ ืชื•ื”ื™ื ื‘ื”ื,
04:07
but nobody knows for sure.
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ืื‘ืœ ืืฃ ืื—ื“ ืœื ื™ื•ื“ืข ืืช ื”ืชืฉื•ื‘ื” ื‘ื‘ื˜ื—ื•ืŸ.
04:09
So far,
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ืขื“ ืขื›ืฉื™ื•,
04:11
we only know of one place in the universe
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ืื ื—ื ื• ืžื›ื™ืจื™ื ืจืง ืžืงื•ื ืื—ื“ ื‘ื™ืงื•ื
04:13
where life exists,
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ื‘ื• ืงื™ื™ืžื™ื ื—ื™ื™ื,
04:15
and that's right here on Earth.
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ื•ื–ื” ืžืžืฉ ืคื” ื‘ื›ื“ื•ืจ ื”ืืจืฅ.
04:17
In the next couple of decades,
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ื‘ืขืฉื•ืจื™ื ื”ื‘ืื™ื,
04:19
as we explore Mars and Europa and Titan,
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ื›ืฉื ื—ืงื•ืจ ืืช ืžืื“ื™ื ืื™ืจื•ืคื” ื•ื˜ื™ื˜ืŸ,
04:22
the discovery of any kind of life there
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ื”ื’ื™ืœื•ื™ ืฉืœ ื›ืœ ืกื•ื’ ื—ื™ื™ื ืฉื
04:26
will mean that life will be abundant
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ื™ืจืื” ืฉื”ื—ื™ื™ื ื™ื”ื™ื• ื ืคื•ืฆื™ื
04:29
in the Milky Way.
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ื‘ืฉื‘ื™ืœ ื”ื—ืœื‘.
04:30
Because if life originated twice
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ืžืคื ื™ ืฉืื ื”ื—ื™ื™ื ื”ืชื—ื™ืœื• ืคืขืžื™ื™ื
04:33
within this one Solar System,
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ื‘ืื•ืชื” ืžืขืจื›ืช ืฉืžืฉ,
04:35
it means it was easy,
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ื–ื” ืื•ืžืจ ืฉื–ื” ื”ื™ื” ืงืœ,
04:37
and given similar conditions elsewhere,
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ื•ื‘ื”ืชื—ืฉื‘ ื‘ืชื ืื™ื ื”ื“ื•ืžื™ื ื‘ืžืงื•ืžื•ืช ืื—ืจื™ื,
04:39
life will happen.
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ื—ื™ื™ื ื™ืชืคืชื—ื•.
04:41
So the number two is a very important number here.
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ืื– ื”ืžืกืคืจ ืฉืชื™ื™ื ื”ื•ื ืžืกืคืจ ืžืื•ื“ ื—ืฉื•ื‘ ืคื”.
04:45
Scientists, including SETI researchers,
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ืžื“ืขื ื™ื, ื›ื•ืœืœ ื—ื•ืงืจื™ SETI,
04:48
often tend to make very crude estimates
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ื ื•ื˜ื™ื ืœืขืฉื•ืช ื”ืฉืขืจื” ื’ืกื”
04:52
and acknowledge that there are very large
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ื•ืœื”ื›ื™ืจ ื‘ื–ื” ืฉื™ืฉื ื ืžืฉืชื ื™ื ืœื ื™ื“ื•ืขื™ื ืžืžืฉ ื’ื“ื•ืœื™ื
04:54
uncertainties in these estimates, in order to make progress.
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ื‘ื”ืขืจื›ื•ืช ื”ืืœื”, ื›ื“ื™ ืœื”ื’ื™ืข ืœื”ืชืงื“ืžื•ืช.
04:57
We think we know
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ืื ื—ื ื• ื—ื•ืฉื‘ื™ื ืฉืื ื—ื ื• ื™ื•ื“ืขื™ื
04:59
that R-star and n-sub-e are both numbers that
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ืฉ R-ื›ื•ื›ื‘ื™ืช ื•ื” e ืฉืœ n ื”ื ืฉื ื™ื™ื”ื ืžืกืคืจื™ื
05:02
are closer to 10 than, say, to one,
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ืฉืงืจื•ื‘ื™ื ื™ื•ืชืจ ืœ10 ืžืืฉืจ, ื ื’ื™ื“, ืœืื—ื“,
05:05
and all the f-factors are less than one.
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ื•ื›ืœ ืžืงื“ืžื™ ื”f ื”ื ืคื—ื•ืช ืžืื—ื“.
05:08
Some of them may be much less than one.
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ื—ืœืงื ื™ื›ื•ืœื™ื ืœื”ื™ื•ืช ื”ืจื‘ื” ืคื—ื•ืช ืžืื—ื“.
05:11
But of all these unknowns,
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ืื‘ืœ ืžื›ืœ ื”ืžืฉืชื ื™ื ื”ืœื ื™ื“ื•ืขื™ื ื”ืืœื”,
05:13
the biggest unknown is L,
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ื”ื‘ืœืชื™ ื™ื“ื•ืข ื”ื›ื™ ื’ื“ื•ืœ ื”ื•ื L,
05:15
so perhaps the most useful version of the Drake equation
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ืื– ืื•ืœื™ ื”ื’ืจืกื” ื”ื›ื™ ื™ืขื™ืœื” ืฉืœ ืžืฉื•ื•ืืช ื“ืจื™ื™ืง
05:19
is simply to say that
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ื”ื™ื ืคืฉื•ื˜ ืœื”ื’ื™ื“
05:21
N is approximately equal to L.
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ืฉ N ืฉื•ื•ื” ื‘ืขืจืš ืœ L.
05:26
The information in this equation is very clear.
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ื”ืžื™ื“ืข ื‘ืžืฉื•ื•ืื” ื”ื–ื• ื”ื•ื ื‘ืจื•ืจ ื‘ื™ื•ืชืจ.
05:29
Unless L is large,
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ืืœื ืื L ื”ื•ื ื’ื“ื•ืœ,
05:31
N will be small.
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N ื™ื”ื™ื” ืงื˜ืŸ.
05:33
But, you know, you can also turn that around.
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ืื‘ืœ, ืืชื ื™ื•ื“ืขื™ื, ืืชื ื™ื›ื•ืœื™ื ื’ื ืœื”ืคื•ืš ืืช ื–ื”.
05:37
If SETI succeeds in detecting a signal in the near future,
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ืื SETI ื™ืฆืœื™ื—ื• ืœื’ืœื•ืช ืื•ืช ื‘ืขืชื™ื“ ื”ืงืจื•ื‘,
05:41
after examining only a small portion
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ืื—ืจื™ ื‘ื—ื™ื ื” ืฉืœ ื—ืœืง ืงื˜ืŸ
05:44
of the stars in the Milky Way,
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ืžื›ืœ ื”ื›ื•ื›ื‘ื™ื ื‘ืฉื‘ื™ืœ ื”ื—ืœื‘,
05:46
then we learn that
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ืื– ืื ื—ื ื• ืœื•ืžื“ื™ื
05:48
L, on average, must be large.
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ืฉ L, ื‘ืžืžื•ืฆืข, ื—ื™ื™ื‘ ืœื”ื™ื•ืช ื’ื“ื•ืœ.
05:50
Otherwise, we couldn't have succeeded so easily.
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ืื—ืจืช, ืœื ื”ื™ื™ื ื• ื™ื›ื•ืœื™ื ืœื”ืฆืœื™ื— ื›ืœ ื›ืš ื‘ืงืœื•ืช.
05:54
A physicist named Philip Morrison
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ืคื™ื–ื™ืงืื™ ื‘ืฉื ืคื™ืœื™ืค ืžื•ืจื™ืกื•ืŸ
05:56
summarizes by saying
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ืกื™ื›ื ื‘ืื•ืžืจื•
05:58
that SETI is the archaeology of the future.
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ืฉ SETI ื”ื ื”ืืจื›ื™ืื•ืœื•ื’ื™ื ืฉืœ ื”ืขืชื™ื“.
06:02
By this, he meant that
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ื•ื‘ื›ืš, ื”ื•ื ื”ืชื›ื•ื•ืŸ
06:03
because the speed of light is finite,
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ืฉื‘ื’ืœืœ ืฉืžื”ื™ืจื•ืช ื”ืื•ืจ ื”ื™ื ืกื•ืคื™ืช,
06:06
any signals detected from distant technologies
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ื›ืœ ืื•ืช ืฉื™ืชื’ืœื” ืžื˜ื›ื ื•ืœื•ื’ื™ื•ืช ืจื—ื•ืงื•ืช
06:09
will be telling us about their past
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ื™ืกืคืจ ืœื ื• ืขืœ ื”ืขื‘ืจ
06:12
by the time they reach us.
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ืขื“ ืฉื”ื•ื ื™ื’ื™ืข ืœื›ืืŸ.
06:14
But because L must be large
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ืื‘ืœ ื‘ื’ืœืœ ืฉ L ื—ื™ื™ื‘ ืœื”ื™ื•ืช ื’ื“ื•ืœ
06:17
for a successful detection,
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ืœื’ื™ืœื•ื™ ืžื•ืฆืœื—,
06:19
we also learn about our future,
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ืื ื—ื ื• ื’ื ืœื•ืžื“ื™ื ืขืœ ืขืชื™ื“ื ื•,
06:22
particularly that we can have a long future.
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ื‘ืขื™ืงืจ ืฉื™ื•ื›ืœ ืœื”ื™ื•ืช ืœื ื• ืขืชื™ื“ ืืจื•ืš.
06:26
We've developed technologies that can send signals into space
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ืคื™ืชื—ื ื• ื˜ื›ื ื•ืœื•ื’ื™ื•ืช ืฉื™ื›ื•ืœื•ืช ืœืฉืœื•ื— ืื•ืชื•ืช ืœื—ืœืœ
06:29
and humans to the moon,
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ื•ืื ืฉื™ื ืœื™ืจื—,
06:31
but we've also developed technologies that can destroy the environment,
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ืื‘ืœ ื’ื ืคื™ืชื—ื ื• ื˜ื›ื ื•ืœื•ื’ื™ื•ืช ืฉื™ื›ื•ืœื•ืช ืœื”ืฉืžื™ื“ ืืช ื”ืกื‘ื™ื‘ื”,
06:34
that can wage war
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ืฉืžืฉืžืฉื•ืช ืœืžืœื—ืžื”
06:36
with weapons and biological terrorism.
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ืขื ื ืฉืงื™ื ื•ื˜ืจื•ืจ ื‘ื™ื•ืœื•ื’ื™.
06:38
In the future,
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ื‘ืขืชื™ื“,
06:39
will our technology help stabilize our planet
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ื”ืื ื”ื˜ื›ื ื•ืœื•ื’ื™ื•ืช ืฉืœื ื• ื™ื™ืฆื‘ื• ืืช ื”ืคืœื ื˜ื”
06:42
and our population,
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ื•ืืช ื”ืื•ื›ืœื•ืกื™ื” ืฉืœื ื•,
06:43
leading to a very long lifetime for us?
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ื•ื™ื•ื‘ื™ืœื• ืœื—ื™ื™ื ืืจื•ื›ื™ื ื‘ืฉื‘ื™ืœื ื•?
06:46
Or will we destroy our world and its inhabitants
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ืื• ื”ืื ื”ืŸ ื™ืฉืžื™ื“ื• ืืช ื”ืขื•ืœื ื•ืืช ืชื•ืฉื‘ื™ื•
06:49
after only a brief appearance on the cosmic stage?
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ืื—ืจื™ ื”ื•ืคืขื” ืงืฆืจื” ืขืœ ื”ื‘ืžื” ื”ืงื•ืกืžื™ืช?
06:53
I encourage you to consider
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ืื ื™ ืžืขื•ื“ื“ืช ืืชื›ื ืœื—ืฉื•ื‘
06:56
the unknowns in this equation.
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ืขืœ ื”ืžืฉืชื ื™ื ื”ื‘ืœืชื™ ื™ื“ื•ืขื™ื ื‘ืžืฉื•ื•ืื”.
06:58
Why don't you make your own estimates
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ืœืžื” ืœื ืชืขืฉื• ื”ืขืจื›ื•ืช ืžืฉืœื›ื
07:00
for these unknowns, and see what you come up with for N?
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ืœืžืฉืชื ื™ื ื”ืืœื”, ื•ืชืจืื• ืœืื™ื–ื” N ืืชื ืžื’ื™ืขื™ื?
07:03
Compare that with the estimates made by Frank Drake,
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ื”ืฉื•ื• ืืช ื–ื” ืขื ื”ื”ืขืจื›ื•ืช ืฉืœ ืคืจื ืง ื“ืจื™ื™ืง,
07:06
Carl Sagan, other scientists
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ืงืืจืœ ืกื™ื™ื’ืŸ, ื•ืžื“ืขื ื™ื ืื—ืจื™ื
07:08
or your neighbors.
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ืื• ืฉื›ื ื™ื›ื.
07:10
Remember, there's no right answer.
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ื–ื›ืจื•, ืื™ืŸ ืชืฉื•ื‘ื” ื ื›ื•ื ื”.
07:13
Not yet.
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ืขื“ื™ื™ืŸ ืœื.
ืขืœ ืืชืจ ื–ื”

ืืชืจ ื–ื” ื™ืฆื™ื’ ื‘ืคื ื™ื›ื ืกืจื˜ื•ื ื™ YouTube ื”ืžื•ืขื™ืœื™ื ืœืœื™ืžื•ื“ ืื ื’ืœื™ืช. ืชื•ื›ืœื• ืœืจืื•ืช ืฉื™ืขื•ืจื™ ืื ื’ืœื™ืช ื”ืžื•ืขื‘ืจื™ื ืขืœ ื™ื“ื™ ืžื•ืจื™ื ืžื”ืฉื•ืจื” ื”ืจืืฉื•ื ื” ืžืจื—ื‘ื™ ื”ืขื•ืœื. ืœื—ืฅ ืคืขืžื™ื™ื ืขืœ ื”ื›ืชื•ื‘ื™ื•ืช ื‘ืื ื’ืœื™ืช ื”ืžื•ืฆื’ื•ืช ื‘ื›ืœ ื“ืฃ ื•ื™ื“ืื• ื›ื“ื™ ืœื”ืคืขื™ืœ ืืช ื”ืกืจื˜ื•ืŸ ืžืฉื. ื”ื›ืชื•ื‘ื™ื•ืช ื’ื•ืœืœื•ืช ื‘ืกื ื›ืจื•ืŸ ืขื ื”ืคืขืœืช ื”ื•ื•ื™ื“ืื•. ืื ื™ืฉ ืœืš ื”ืขืจื•ืช ืื• ื‘ืงืฉื•ืช, ืื ื ืฆื•ืจ ืื™ืชื ื• ืงืฉืจ ื‘ืืžืฆืขื•ืช ื˜ื•ืคืก ื™ืฆื™ืจืช ืงืฉืจ ื–ื”.

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