Life in the Universe (4th Edition)
4th Edition
ISBN: 9780134089089
Author: Jeffrey O. Bennett, Seth Shostak
Publisher: PEARSON
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Chapter 12, Problem 39IF
To determine
If number of civilization in galaxy is large then is it necessary that they exist even todays.
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Students have asked these similar questions
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.
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Which of the following is not considered a likely solution to the question of why we are not currently aware of an extraterrestrial civilization?
Group of answer choices
There is no civilization because civilizations are not common.
The civilization is probably undetectable to us because it makes use of technologies that do not obey the known laws of physics.
There is no galactic civilization because civilizations do not leave their home worlds.
There is no civilization because most civilizations destroy themselves before achieving interstellar travel.
The civilization is deliberately avoiding contact with us.
Chapter 12 Solutions
Life in the Universe (4th Edition)
Ch. 12 - What is the purpose of the Drake equation? Define...Ch. 12 - What is convergent evolution? How does this idea...Ch. 12 - Prob. 3RQCh. 12 - Prob. 4RQCh. 12 - Briefly describe early attempts at interplanetary...Ch. 12 - Briefly discuss early SETI efforts. What do we...Ch. 12 - What are the three general categories of signals...Ch. 12 - Why do SETI researchers assume that beacon signals...Ch. 12 - Summarize the current techniques of radio SETI and...Ch. 12 - Explain why it is reasonable to imagine optical or...
Ch. 12 - Prob. 11RQCh. 12 - What are the three distinct categories of...Ch. 12 - Briefly discuss some of the issues that would...Ch. 12 - Discuss several types of claims about alien...Ch. 12 - Humans are the crown of creation and an inevitable...Ch. 12 - If, for some reason, we humans were to suddenly...Ch. 12 - Prob. 17TYUCh. 12 - Most of the intelligence in the universe is not...Ch. 12 - Because SETI researchers are listening to star...Ch. 12 - Prob. 20TYUCh. 12 - Prob. 21TYUCh. 12 - Looking for signals from star systems is a poor...Ch. 12 - If 10,000 people saw the same UFO, scientists...Ch. 12 - The absence of any scientific evidence for alien...Ch. 12 - The end result of a calculation with the Drake...Ch. 12 - Which of the following statements is true about...Ch. 12 - The fact that marine predators like dolphins and...Ch. 12 - Which of the following would lead an animal to a...Ch. 12 - Prob. 29TYUCh. 12 - Why are we more likely to be able to detect a...Ch. 12 - What is the distinguishing characteristic that...Ch. 12 - Two-way conversation with other societies is...Ch. 12 - Prob. 33TYUCh. 12 - One reason scientists doubt that crop circles have...Ch. 12 - Alien Visits. Learn more about a particular claim...Ch. 12 - Prob. 39IFCh. 12 - Evolution of Intelligence. Based on your...Ch. 12 - Intelligence on Other Worlds. Consider again the...Ch. 12 - Talking Back. Suppose SETI were to find a signal...Ch. 12 - Contact. Watch the movie Contact, paying careful...Ch. 12 - Invasions of Movie Aliens. Choose a science...Ch. 12 - Prob. 47IFCh. 12 - Actual SETI Searches. Project Phoenix, the largest...Ch. 12 - Power Used by E.T. A modern SETI search using the...Ch. 12 - Detecting Signals. SETI scientists are sometimes...Ch. 12 - Societal Reaction. It is frequently said that the...Ch. 12 - Dealing with UFO Claims. Given the large number of...
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- Tutorial 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_forwardA 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_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_forwardWhy are we limited to finding life on planets orbiting other stars to situations where the biosphere has created planet-scale changes?arrow_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
- 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_forwardThe 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.arrow_forwardTRUE 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_forward
- Put 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_forwardSuppose 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_forwardIf you represent Earths history by a line that is 1 m long, how long a segment would represent the 400 million years since life first moved onto the land? How long a segment would represent the 4-millionyear history of humanoid life?arrow_forward
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