Horizons: Exploring the Universe (MindTap Course List)
14th Edition
ISBN: 9781305960961
Author: Michael A. Seeds, Dana Backman
Publisher: Cengage Learning
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Chapter 20, Problem 8P
Calculate the numb of communicative civilizations per galaxy using your n estimates of the factors in Table 20-1.
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The Drake equation In 1961 astronomer Frank Drakedeveloped an equation to try to estimate the number ofextraterrestrial civilizations in our galaxy that might be
able to communicate with us via radio transmissions. Nowlargely accepted by the scientific community, the Drakeequation has helped spur efforts by radio astronomers tosearch for extraterrestrial intelligence. Here is the equation:
NC = N # fp # ne # fl# fi# fc # fLOK, it looks a little messy, but here’s what it means:So, how many ETs are out there? That depends; valueschosen for the many factors in the equation depend onever-evolving scientific knowledge and one’s personalguesses. But now, some questions.a) What quantity is calculated by the first product, N # fp?b) What quantity is calculated by the product, N # fp # ne # fl?c) What probability is calculated by the product fl# fi?d) Which of the factors in the formula are conditionalprobabilities? Restate each in a way that makes thecondition clear.
The Drake equation attempts to calculate the number of communicative civilizations in the galaxy. What does the factor F S represent and why is it considered to be the most uncertain of all the factors in this equation?
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Chapter 20 Solutions
Horizons: Exploring the Universe (MindTap Course List)
Ch. 20 - If life is based on information, what is that...Ch. 20 - How does the DNA molecule produce a copy of...Ch. 20 - What would happen to a life-form if the genetic...Ch. 20 - What would happen to a life-form if the...Ch. 20 - Give an example of natural selection acting on new...Ch. 20 - Prob. 6RQCh. 20 - Why do scientists generality think that liquid...Ch. 20 - Prob. 8RQCh. 20 - What is the significance of the Miller-Urey...Ch. 20 - Prob. 10RQ
Ch. 20 - Prob. 11RQCh. 20 - Why is it reasonable to suspect that travel...Ch. 20 - How does the stability of technological...Ch. 20 - Prob. 14RQCh. 20 - Prob. 15RQCh. 20 - Prob. 16RQCh. 20 - How Do We know? Why are scientists confident that...Ch. 20 - Do you expect that hypothetical alien recipients...Ch. 20 - Prob. 2DQCh. 20 - Prob. 3DQCh. 20 - A single human cell encloses about 1.5 m of DNA,...Ch. 20 - If you represent Earth’s history by a line 1 m...Ch. 20 - Prob. 3PCh. 20 - If a star must remain on the main sequence for at...Ch. 20 - Prob. 5PCh. 20 - Prob. 6PCh. 20 - Prob. 7PCh. 20 - Calculate the numb of communicative civilizations...Ch. 20 - The star cluster shown in the image in Figure UN...Ch. 20 - Prob. 2LTL
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Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, physics and related others by exploring similar questions and additional content below.Similar questions
- What is the difference between chemical evolution and biological evolution?arrow_forwardConsider Figure 25-8. What is the ratio of the length of time since the origin of fish to the time since the origin of mammals? What does this value indicate?arrow_forwardWhy are upper-main-sequence (high-luminosity) host stars unlikely sites for intelligent civilizations?arrow_forward
- What are the advantages to using radio waves for communication between civilizations that live around different stars? List as many as you can.arrow_forwardTutorial A radio broadcast left Earth in 1923. How far in light years has it traveled? If there is, on average, 1 star system per 400 cubic light years, how many star systems has this broadcast reached? Assume that the fraction of these star systems that have planets is 0.50 and that, in a given planetary system, the average number of planets that have orbited in the habitable zone for 4 billion years is 0.40. How many possible planets with life could have heard this signal? Part 1 of 3 To figure out how many light years a signal has traveled we need to know how long since the signal left Earth. If the signal left in 1923, distance in light years = time since broadcast left Earth. d = tnow - broadcast d = 97 97 light years Part 2 of 3 Since the radio signal travels in all directions, it expanded as a sphere with a radius equal to the distance it has traveled so far. To determine the number of star systems this signal has reached, we need to determine the volume of that sphere. V, = Vb…arrow_forwardPut in order the organization levels for life: Organs→ - Organisms Populations :: Tissues :: Ecosystems : Organ systems : Cells : Communities 1 2 3 4 5 6 7 Support | Schoology Blog | PRIVACY POLIarrow_forward
- Suppose there are l0,000 civilizations broadcasting radio signals in the Milky Way GaIaxy right now. On average, how many stars would we have to search before we would expect to hear a signal? Assume there are 500 billion stars in the galaxy. How would the answer change if there were only 100 civilizations instead of 10,000?arrow_forwardSuppose there are 9000.0 civilizations broadcasting radio signals in the Milky Way Galaxy at the moment. On average, how many stars would have to be searched before a signal is heard? Assume that there are 8 × 1011 stars in the Galaxy and one civilization per star.arrow_forwardTutorial A radio broadcast left Earth in 1925. How far in light years has it traveled? If there is, on average, 1 star system per 400 cubic light years, how many star systems has this broadcast reached? Assume that the fraction of these star systems that have planets is 0.30 and that, in a given planetary system, the average number of planets that have orbited in the habitable zone for 4 billion years is 0.85. How many possible planets with life could have heard this signal? Part 1 of 3 To figure out how many light years a signal has traveled we need to know how long since the signal left Earth. If the signal left in 1925, distance in light years = time since broadcast left Earth. d = tnow - tbroadcast d = light years Submit Skip (you cannot come back)arrow_forward
- TRUE OR FALSE: According to an optimistic evaluation of Frank Drake’s equation, there can be as many as ten thousand technologically communicative civilizations in our Milky Way galaxy alone.arrow_forwardI don’t understand how that it was estimated as length of a mouse is 4 to 15 cm in length. Is that a guess and the answer just varies?also where did 10^-1 come fromarrow_forwardThe Drake equation tells us that the number of technological civilizations in our Galaxy at this time is: Group of answer choices About 100,000. About 14 billion. About 200 billion. It cannot predict this number at this time. About 6,000. About 1 million. Somewhere in the range 1-10.arrow_forward
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