From the Ted Talk by Jill Tarter: Calculating the odds of intelligent alien life
Unscramble the Blue Letters
(Music) The baisc qoieutsn is, does life exist beyond etarh? senctstiis who are called astrobiologists are trying to find that out right now. Most asgtiioobstrlos are trying to figure out if there's microbial life on Mars, or in the ocean under the frozen surface of Jupiter's moon Europa, or in the liquid hdaorybrcon lakes that we've found on Saturn's moon Titan. But one group of astrobiologists works on SETI. SETI is the seacrh for Extraterrestrial Intelligence, and SETI researchers are trying to detect some evidence that intelligent creatures elsewhere have used technology to biuld a transmitter of some sort. But how likely is it that they will manage to find a signal? There are certainly no gaeauntres when it comes to SETI, but something called the Drake equation, neamd after Frank Drake, can help us organize our thinking about what might be required for successful dtteiocen. If you've dealt with equations before, then you probably expect that there will be a solution to the equation, a right answer. The dkrae equation, however, is different, because there are so many unknowns. It has no right answer. As we learn more about our universe and our place within it, some of the unknowns get better known, and we can estimate an answer a bit better. But there won't be a dntiefie aewnsr to the Drake equation until SETI succeeds or something else proves that Earthlings are the only intelligent species in our portion of the cosmos. In the meantime, it is really useful to consider the uonnwnks. The Drake equation attempts to estimate the number of togaheoclnicl civilizations in the Milky Way Galaxy — we call that N — with whom we could make contact, and it's usually written as: N equals R-star multiplied by f-sub-p multiplied by n-sub-e multiplied by f-sub-l multiplied by f-sub-i meliiltpud by f-sub-c and lastly, multiplied by capital L. All those factors multiplied together help to eatmtise the number of technological civilizations that we might be able to detect right now. R-star is the rate at which srats have been born in the mliky Way Galaxy over the last few billion years, so it's a number that is stars per year. Our galaxy is 10 billion years old, and early in its history stars formed at a different rate. All of the f-factors are fractions. Each one must be less than or equal to one. F-sub-p is the fraction of stars that have planets. N-sub-e is the average number of habitable planets in any planetary system. F-sub-l is the fraction of planets on which life actually begins and f-sub-i is the fraction of all those life forms that deoevlp icleenilntge. F-sub-c is the fraction of intelligent life that develops a cvaiztliioin that decides to use some sort of transmitting tchoolgney. And finally, L — the longevity factor. On average, how many years do those transmitters continue to operate? Astronomers are now almost able to tell us what the product of the first three tmres is. We're now finding eelnaoxtps almost everywhere. The fctniaros dealing with life and intelligence and technological civilizations are ones that many, many experts pedonr, but nobody knows for sure. So far, we only know of one place in the universe where life esixts, and that's right here on Earth. In the next couple of decades, as we explore Mars and erpuoa and Titan, the discovery of any kind of life there will mean that life will be abundant in the Milky Way. Because if life originated twice within this one Solar System, it mnaes it was easy, and given siamlir conditions elsewhere, life will happen. So the nmbeur two is a very inpamortt number here. Scientists, including SETI researchers, often tend to make very crude estimates and acknowledge that there are very lagre ucntenreatiis in these estimates, in order to make progress. We think we know that R-star and n-sub-e are both nbmuers that are closer to 10 than, say, to one, and all the f-factors are less than one. Some of them may be much less than one. But of all these unknowns, the biggest unnwokn is L, so perhaps the most useful version of the Drake equation is smlpiy to say that N is approximately equal to L. The information in this equation is very clear. Unless L is large, N will be small. But, you know, you can also turn that around. If SETI succeeds in detecting a signal in the near future, after eiiaxnmng only a small portion of the stars in the Milky Way, then we learn that L, on average, must be large. Otherwise, we couldn't have sueeeccdd so easily. A physicist named Philip Morrison summarizes by saying that SETI is the archaeology of the future. By this, he meant that because the seepd of light is finite, any signals detected from distant technologies will be telling us about their past by the time they reach us. But because L must be large for a successful detection, we also laren about our future, particularly that we can have a long future. We've developed technologies that can send signals into space and humans to the moon, but we've also developed technologies that can dosrtey the environment, that can wage war with wopeans and biological terrorism. In the ftuure, will our technology help szatiilbe our planet and our population, leading to a very long lifetime for us? Or will we destroy our world and its inhabitants after only a brief appearance on the csoimc stage? I encourage you to consider the unknowns in this equation. Why don't you make your own estimates for these unknowns, and see what you come up with for N? Compare that with the estimates made by Frank Drake, Carl Sagan, other scientists or your neighbors. Remember, there's no right answer. Not yet.
Open Cloze
(Music) The _____________ is, does life exist beyond _____? __________ who are called astrobiologists are trying to find that out right now. Most _______________ are trying to figure out if there's microbial life on Mars, or in the ocean under the frozen surface of Jupiter's moon Europa, or in the liquid ___________ lakes that we've found on Saturn's moon Titan. But one group of astrobiologists works on SETI. SETI is the ______ for Extraterrestrial Intelligence, and SETI researchers are trying to detect some evidence that intelligent creatures elsewhere have used technology to _____ a transmitter of some sort. But how likely is it that they will manage to find a signal? There are certainly no __________ when it comes to SETI, but something called the Drake equation, _____ after Frank Drake, can help us organize our thinking about what might be required for successful _________. If you've dealt with equations before, then you probably expect that there will be a solution to the equation, a right answer. The _____ equation, however, is different, because there are so many unknowns. It has no right answer. As we learn more about our universe and our place within it, some of the unknowns get better known, and we can estimate an answer a bit better. But there won't be a ______________ to the Drake equation until SETI succeeds or something else proves that Earthlings are the only intelligent species in our portion of the cosmos. In the meantime, it is really useful to consider the ________. The Drake equation attempts to estimate the number of _____________ civilizations in the Milky Way Galaxy — we call that N — with whom we could make contact, and it's usually written as: N equals R-star multiplied by f-sub-p multiplied by n-sub-e multiplied by f-sub-l multiplied by f-sub-i __________ by f-sub-c and lastly, multiplied by capital L. All those factors multiplied together help to ________ the number of technological civilizations that we might be able to detect right now. R-star is the rate at which _____ have been born in the _____ Way Galaxy over the last few billion years, so it's a number that is stars per year. Our galaxy is 10 billion years old, and early in its history stars formed at a different rate. All of the f-factors are fractions. Each one must be less than or equal to one. F-sub-p is the fraction of stars that have planets. N-sub-e is the average number of habitable planets in any planetary system. F-sub-l is the fraction of planets on which life actually begins and f-sub-i is the fraction of all those life forms that ___________________. F-sub-c is the fraction of intelligent life that develops a ____________ that decides to use some sort of transmitting __________. And finally, L — the longevity factor. On average, how many years do those transmitters continue to operate? Astronomers are now almost able to tell us what the product of the first three _____ is. We're now finding __________ almost everywhere. The _________ dealing with life and intelligence and technological civilizations are ones that many, many experts ______, but nobody knows for sure. So far, we only know of one place in the universe where life ______, and that's right here on Earth. In the next couple of decades, as we explore Mars and ______ and Titan, the discovery of any kind of life there will mean that life will be abundant in the Milky Way. Because if life originated twice within this one Solar System, it _____ it was easy, and given _______ conditions elsewhere, life will happen. So the ______ two is a very _________ number here. Scientists, including SETI researchers, often tend to make very crude estimates and acknowledge that there are very __________________ in these estimates, in order to make progress. We think we know that R-star and n-sub-e are both _______ that are closer to 10 than, say, to one, and all the f-factors are less than one. Some of them may be much less than one. But of all these unknowns, the biggest _______ is L, so perhaps the most useful version of the Drake equation is ______ to say that N is approximately equal to L. The information in this equation is very clear. Unless L is large, N will be small. But, you know, you can also turn that around. If SETI succeeds in detecting a signal in the near future, after _________ only a small portion of the stars in the Milky Way, then we learn that L, on average, must be large. Otherwise, we couldn't have _________ so easily. A physicist named Philip Morrison summarizes by saying that SETI is the archaeology of the future. By this, he meant that because the _____ of light is finite, any signals detected from distant technologies will be telling us about their past by the time they reach us. But because L must be large for a successful detection, we also _____ about our future, particularly that we can have a long future. We've developed technologies that can send signals into space and humans to the moon, but we've also developed technologies that can _______ the environment, that can wage war with _______ and biological terrorism. In the ______, will our technology help _________ our planet and our population, leading to a very long lifetime for us? Or will we destroy our world and its inhabitants after only a brief appearance on the ______ stage? I encourage you to consider the unknowns in this equation. Why don't you make your own estimates for these unknowns, and see what you come up with for N? Compare that with the estimates made by Frank Drake, Carl Sagan, other scientists or your neighbors. Remember, there's no right answer. Not yet.
Solution
stars
terms
speed
numbers
astrobiologists
number
answer
technology
cosmic
drake
civilization
destroy
estimate
scientists
simply
search
future
milky
weapons
examining
important
basic
guarantees
unknown
multiplied
learn
build
hydrocarbon
develop
large
similar
stabilize
ponder
detection
definite
intelligence
exists
uncertainties
succeeded
earth
question
fractions
europa
means
exoplanets
technological
named
unknowns
Original Text
(Music) The basic question is, does life exist beyond Earth? Scientists who are called astrobiologists are trying to find that out right now. Most astrobiologists are trying to figure out if there's microbial life on Mars, or in the ocean under the frozen surface of Jupiter's moon Europa, or in the liquid hydrocarbon lakes that we've found on Saturn's moon Titan. But one group of astrobiologists works on SETI. SETI is the Search for Extraterrestrial Intelligence, and SETI researchers are trying to detect some evidence that intelligent creatures elsewhere have used technology to build a transmitter of some sort. But how likely is it that they will manage to find a signal? There are certainly no guarantees when it comes to SETI, but something called the Drake equation, named after Frank Drake, can help us organize our thinking about what might be required for successful detection. If you've dealt with equations before, then you probably expect that there will be a solution to the equation, a right answer. The Drake equation, however, is different, because there are so many unknowns. It has no right answer. As we learn more about our universe and our place within it, some of the unknowns get better known, and we can estimate an answer a bit better. But there won't be a definite answer to the Drake equation until SETI succeeds or something else proves that Earthlings are the only intelligent species in our portion of the cosmos. In the meantime, it is really useful to consider the unknowns. The Drake equation attempts to estimate the number of technological civilizations in the Milky Way Galaxy — we call that N — with whom we could make contact, and it's usually written as: N equals R-star multiplied by f-sub-p multiplied by n-sub-e multiplied by f-sub-l multiplied by f-sub-i multiplied by f-sub-c and lastly, multiplied by capital L. All those factors multiplied together help to estimate the number of technological civilizations that we might be able to detect right now. R-star is the rate at which stars have been born in the Milky Way Galaxy over the last few billion years, so it's a number that is stars per year. Our galaxy is 10 billion years old, and early in its history stars formed at a different rate. All of the f-factors are fractions. Each one must be less than or equal to one. F-sub-p is the fraction of stars that have planets. N-sub-e is the average number of habitable planets in any planetary system. F-sub-l is the fraction of planets on which life actually begins and f-sub-i is the fraction of all those life forms that develop intelligence. F-sub-c is the fraction of intelligent life that develops a civilization that decides to use some sort of transmitting technology. And finally, L — the longevity factor. On average, how many years do those transmitters continue to operate? Astronomers are now almost able to tell us what the product of the first three terms is. We're now finding exoplanets almost everywhere. The fractions dealing with life and intelligence and technological civilizations are ones that many, many experts ponder, but nobody knows for sure. So far, we only know of one place in the universe where life exists, and that's right here on Earth. In the next couple of decades, as we explore Mars and Europa and Titan, the discovery of any kind of life there will mean that life will be abundant in the Milky Way. Because if life originated twice within this one Solar System, it means it was easy, and given similar conditions elsewhere, life will happen. So the number two is a very important number here. Scientists, including SETI researchers, often tend to make very crude estimates and acknowledge that there are very large uncertainties in these estimates, in order to make progress. We think we know that R-star and n-sub-e are both numbers that are closer to 10 than, say, to one, and all the f-factors are less than one. Some of them may be much less than one. But of all these unknowns, the biggest unknown is L, so perhaps the most useful version of the Drake equation is simply to say that N is approximately equal to L. The information in this equation is very clear. Unless L is large, N will be small. But, you know, you can also turn that around. If SETI succeeds in detecting a signal in the near future, after examining only a small portion of the stars in the Milky Way, then we learn that L, on average, must be large. Otherwise, we couldn't have succeeded so easily. A physicist named Philip Morrison summarizes by saying that SETI is the archaeology of the future. By this, he meant that because the speed of light is finite, any signals detected from distant technologies will be telling us about their past by the time they reach us. But because L must be large for a successful detection, we also learn about our future, particularly that we can have a long future. We've developed technologies that can send signals into space and humans to the moon, but we've also developed technologies that can destroy the environment, that can wage war with weapons and biological terrorism. In the future, will our technology help stabilize our planet and our population, leading to a very long lifetime for us? Or will we destroy our world and its inhabitants after only a brief appearance on the cosmic stage? I encourage you to consider the unknowns in this equation. Why don't you make your own estimates for these unknowns, and see what you come up with for N? Compare that with the estimates made by Frank Drake, Carl Sagan, other scientists or your neighbors. Remember, there's no right answer. Not yet.