MODIFIED MAST ASTRONOMY:COSMIC PERSPECTI
9th Edition
ISBN: 9780136904496
Author: Bennett
Publisher: PEARSON
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Chapter 24, Problem 51EAP
What’s Wrong with This Picture? Many science fiction stories have imagined the galaxy divided into a series of empires, each having arisen from a different civilization on a different world, that hold one another at bay because they all have about the same level of military technology. Is this a realistic scenario? Explain.
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200 years has passed and now it is year 2220. The Earth is out of basic resourcesas they have been drastically drained in the past 200 years. The president of theUnited World Council (UWC) has approved you and your crew’s Mission toMars. You will pilot the most advanced spaceship the world has ever known, theExcelsior! It will carry equipment that will help to transform Mars so as toresemble the Earth, especially so that it can support human life.Before the mission can launch a few items need to be figured out. What is thecapacity of the fuel tank? How long should the fuel burn to achieve escapevelocity (otherwise the Excelsior will be stuck in the Earth’s gravitational pull)?How long will it take the Excelsior to arrive at Mars?1. The ground crew is filling the fuel tanks. You know th
Which of the following seems least reasonable regarding life on Earth?
Group of answer choices
There is much scientific evidence suggesting that all creatures living on Earth today appear to have evolved from a common ancestor.
Louis Pasteur discredited the concept of spontaneous generation by demonstrating that even bacteria and other microorganisms arise from parents resembling themselves.
There is ample physical evidence that the earliest life forms on Earth were multicellular creatures, perhaps resembling some of our primitive fish.
When the earth formed some 4.6 billion years ago, it was a lifeless, inhospitable place.
Before the mid-17th century, most people believed that God had created humankind and other higher organisms and that insects, frogs, and other small creatures could arise spontaneously in mud or decaying matter
About billion years into its development, the Earth it was teeming with organisms resembling blue-green algae.
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.
Chapter 24 Solutions
MODIFIED MAST ASTRONOMY:COSMIC PERSPECTI
Ch. 24 - Prob. 1VSCCh. 24 - Prob. 2VSCCh. 24 - Prob. 3VSCCh. 24 - Prob. 4VSCCh. 24 - Prob. 5VSCCh. 24 - Prob. 6VSCCh. 24 - Prob. 1EAPCh. 24 - Prob. 2EAPCh. 24 - Prob. 3EAPCh. 24 - Prob. 4EAP
Ch. 24 - How are laboratory experiments helping us study...Ch. 24 - Prob. 6EAPCh. 24 - Prob. 7EAPCh. 24 - Prob. 8EAPCh. 24 - Prob. 9EAPCh. 24 - Prob. 10EAPCh. 24 - Prob. 11EAPCh. 24 - Prob. 12EAPCh. 24 - Prob. 13EAPCh. 24 - Prob. 14EAPCh. 24 - Prob. 15EAPCh. 24 - Prob. 16EAPCh. 24 - Prob. 17EAPCh. 24 - For each of the following futuristic scenarios,...Ch. 24 - Prob. 19EAPCh. 24 - Prob. 20EAPCh. 24 - Prob. 21EAPCh. 24 - Prob. 22EAPCh. 24 - Prob. 23EAPCh. 24 - Prob. 24EAPCh. 24 - Prob. 25EAPCh. 24 - Prob. 26EAPCh. 24 - Choose the best answer to each of the following....Ch. 24 - Choose the best answer to each of the following....Ch. 24 - Choose the best answer to each of the following....Ch. 24 - Choose the best answer to each of the following....Ch. 24 - Choose the best answer to each of the following....Ch. 24 - Prob. 32EAPCh. 24 - Choose the best answer to each of the following....Ch. 24 - Prob. 34EAPCh. 24 - Choose the best answer to each of the following....Ch. 24 - Prob. 36EAPCh. 24 - The Turning Point. The end of this chapter...Ch. 24 - Prob. 39EAPCh. 24 - Prob. 43EAPCh. 24 - Prob. 45EAPCh. 24 - Prob. 46EAPCh. 24 - Prob. 47EAPCh. 24 - Prob. 48EAPCh. 24 - Prob. 49EAPCh. 24 - Prob. 50EAPCh. 24 - What’s Wrong with This Picture? Many science...Ch. 24 - Nearest Civilization. Suppose there are 10,000...Ch. 24 - SETI Search. Suppose there are 10,000...Ch. 24 - SETI Signal. Consider a civilization broadcasting...Ch. 24 - Prob. 56EAPCh. 24 - Prob. 57EAP
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- Which of the following is least reasonable regarding the difficulty in contacting extraterrestrial life using space flight and radio communication. Group of answer choices Space flight to the nearest star would take thousands of years with current technology. Even if another intelligent civilization is within a few hundred light-years of us, conversations would be very slow with a turnaround time of decades or even centuries. The spacecraft that NASA sent to Proxima Centauri a few years ago should be approaching its target within a decade or two, depending on solar wind conditions. Earth has been broadcasting at radio wavelengths since the 1930's, so any civilization within a radius of about 100 light-years or so could have received the broadcast by now. Without some major breakthrough, interstellar space flight is totally impractical.arrow_forwardLanguage history Refer to Exercise 48 of Section 5.2. If a language originally had No basic words of which N(t) are still in use, then N(t) ured in millennia. After how many years are one-half the No(0.805)', where time t is meas- basic words still in use?arrow_forwardWhat are the advantages to using radio waves for communication between civilizations that live around different stars? List as many as you can.arrow_forward
- A radio broadcast left Earth in 1911. 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 0.20. How many possible planets with life could have heard this signal?arrow_forwardCalculate the numb of communicative civilizations per galaxy using your n estimates of the factors in Table 20-1.arrow_forwardAccording to modern science, Earth is about 4.5 billion years old and written human history extends back about 10,000 years. Suppose the entire history of Earth is represented with a 100-meter-long timeline, with the birth of Earth on one end and today at the other end. a. What distance represents 1 billion years? b. How far from the end of the timeline does written human history begin? a. 1 billion years is represented by meters of the timeline. (Type an integer or decimal rounded to the nearest tenth as needed.) millimeters from the end of the timeline. b. Written human history begins about (Type an integer or decimal rounded to the nearest hundredth as needed.)arrow_forward
- If we send astronauts to Mars, there will be a time delay anytime we send or receive messages to them here on Earth. Given that Mars is an average of 54.6 million km away from Earth, how long is this time delay for a 2-way 'round-trip' communication - sent to Earth, then back to Mars? (this might be important in emergency situations) answer choices a)About 4 minutes. b)About 30 seconds. c)About 10 seconds. d)About 6 minutes.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_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
- What is the difference between chemical evolution and biological evolution?arrow_forwardHow Do We know? How would you respond to someone who said, about biological evolution, “Oh, that’s only a theory.?arrow_forward18. An intelligent alien living on a planet in the solar system orbiting Alpha Centauri, the nearest star system to our Solar System in the Milky Way Galaxy, receives radio signals from Earth traveling at 186,421 miles/hour. The signal asks if the Alien likes McDonald Burgers. How long, in years, would it take for an Earthling to receive the answer back, Yes! (The distance from Earth to Alpha Centauri = 4.367 light years away, 1 light year = 6.0 x 10" miles, and 1 year = 365.2422 days) 12arrow_forward
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