Life in the Universe (4th Edition)
4th Edition
ISBN: 9780134089089
Author: Jeffrey O. Bennett, Seth Shostak
Publisher: PEARSON
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Question
Chapter 6, Problem 48IF
To determine
The four crucial events for existence of human life.
Expert Solution & Answer
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Check out a sample textbook solutionStudents have asked these similar questions
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.
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…
Tutorial
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
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Chapter 6 Solutions
Life in the Universe (4th Edition)
Ch. 6 - What are the three lines of fossil evidence that...Ch. 6 - How do studies of DNA sequences allow us to...Ch. 6 - Based on current evidence, what locations on Earth...Ch. 6 - What was the MillerUrey experiment, and how did it...Ch. 6 - What do we mean by an RNA world, and why do...Ch. 6 - Briefly summarize current ideas about the sequence...Ch. 6 - Briefly discuss the possibility that life migrated...Ch. 6 - Why do we think that evolution would have...Ch. 6 - Briefly discuss the early evolution of life, from...Ch. 6 - How do we think that eukaryotes evolved? What time...
Ch. 6 - What was the Cambrian explosion? Briefly discuss...Ch. 6 - How and when did life colonize land? Why did it...Ch. 6 - How do we know that the early Earth could not have...Ch. 6 - Summarize the history of the oxygen buildup as it...Ch. 6 - What was the KT impact, and how is it thought to...Ch. 6 - Briefly discuss the evidence for other mass...Ch. 6 - Discuss the threat that future impacts may pose to...Ch. 6 - Describe several adaptations that evolved so...Ch. 6 - When did hominids arise, and when did modern...Ch. 6 - Briefly describe and clarify a few common...Ch. 6 - Prob. 21RQCh. 6 - Briefly describe two main approaches to creating...Ch. 6 - We discover evidence of life, in the form of a...Ch. 6 - We discover an intact fossil of a eukaryotic cell,...Ch. 6 - We discover a preserved, 3.5-billion-year-old...Ch. 6 - We discover clear evidence that life arose on a...Ch. 6 - We discover a fossil of a large dinosaur that...Ch. 6 - We discover that, contrary to present belief,...Ch. 6 - We discover a crater from the impact of a...Ch. 6 - We discover an asteroid about 300 meters across...Ch. 6 - We find fossil remains of an early primate that...Ch. 6 - The first life created in the laboratory has an...Ch. 6 - The origin of life on Earth most likely occurred...Ch. 6 - The earliest living organisms probably were (a)...Ch. 6 - Prob. 35TYUCh. 6 - RNA world refers to (a) the possibility that life...Ch. 6 - Early life arose in an oxygen-free environment,...Ch. 6 - The oxygen in Earths atmosphere was originally...Ch. 6 - The Cambrian explosion refers to (a) a dramatic...Ch. 6 - Prob. 40TYUCh. 6 - The hypothesis that an impact killed the dinosaurs...Ch. 6 - According to the fossil evidence, modern humans...Ch. 6 - Origin of Life Studies. We cannot go back in time...Ch. 6 - A Brief History of Life on Earth. Take all the...Ch. 6 - Geology and Life. In Chapter 4, we discussed the...Ch. 6 - Prob. 48IFCh. 6 - Prob. 49IFCh. 6 - Impact Movie Review. Watch one of the Hollywood...Ch. 6 - Artificial Life Review. Numerous science fiction...Ch. 6 - Bacterial Evolution. Suppose that a mutation...Ch. 6 - Deep in Bacteria. In Cosmic Calculations 6.1, we...Ch. 6 - Prob. 54IFCh. 6 - Human Population Growth. During the twentieth...Ch. 6 - Impact Energy. Consider a comet about 2 kilometers...Ch. 6 - The Missing Link. As we discussed in this chapter,...Ch. 6 - Evolution by Choice. Consider the technology we...
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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_forwardWhat 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_forward
- Suppose astronomers discover a radio message from a civilization whose planet orbits a star 35 lightyears away. Their message encourages us to send a radio answer, which we decide to do. Suppose our governing bodies take 2 years to decide whether and how to answer. When our answer arrives there, their governing bodies also take two of our years to frame an answer to us. How long after we get their first message can we hope to get their reply to ours? (A question for further thinking: Once communication gets going, should we continue to wait for a reply before we send the next message?)arrow_forwardWhich 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.arrow_forwardasap pleasearrow_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_forwardWater is life. Nothing survives without water. Water is abundant everywhere. Now, we said before that water contains the primary components of good fuel. The hydrogen. Is there is a possibility that water will be a source of Hydrogen? Or we mean, we can subject water in a certain process and we are deriving Hydrogen from it continuously? If yes, how?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
- In a globular cluster, astronomers (someday) discover a star with the same mass as our Sun, but consisting entirely of hydrogen and helium. Is this star a good place to point our SETI antennas and search for radio signals from an advanced civilization? Group of answer choices No, because such a star (and any planets around it) would not have the heavier elements (carbon, nitrogen, oxygen, etc.) that we believe are necessary to start life as we know it. Yes, because globular clusters are among the closest star clusters to us, so that they would be easy to search for radio signals. Yes, because we have already found radio signals from another civilization living near a star in a globular cluster. No, because such a star would most likely not have a stable (main-sequence) stage that is long enough for a technological civilization to develop. Yes, because such a star is probably old and a technological civilization will have had a long time to evolve and develop there.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_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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