Horizons: Exploring the Universe (MindTap Course List)
14th Edition
ISBN: 9781305960961
Author: Michael A. Seeds, Dana Backman
Publisher: Cengage Learning
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Question
Chapter 20, Problem 14RQ
To determine
To Explain:
The water hole and why it is considered as a good place to search for extraterrestrial civilization?
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Students have asked these similar questions
The 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.
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.
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…
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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- What are the advantages to using radio waves for communication between civilizations that live around different stars? List as many as you can.arrow_forwardIf we do find life on Mars, what might be some ways to check whether it formed separately from Earth life, or whether exchanges of material between the two planets meant that the two forms of life have a common origin?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
- Why are scientists confident Earth has never been visited by aliens?arrow_forwardWhat are some reasons that more advanced civilizations might want to send out messages to other star systems?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
- Most of the stars we can see with the unaided eye in our night sky are hundreds or even thousands of lightyears away from Earth. (The very closest ones are only a few dozen lightyears away, but most are much further.) The vast majority of stars in our galaxy are many tens of thousands of lightyears away. IF intelligent life existed on planets orbiting some of these stars – and that’s a huge IF! – comment on the likelihood and practicality of (a) visiting, (b) communicating with, or (c) verifying the existence of those life forms. Describe how you might go about approaching EACH of these three tasks, or if you think they are even possible. (One or two sentences for each part would be appropriate.)arrow_forwardWhich 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.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
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