Life in the Universe (4th Edition)
4th Edition
ISBN: 9780134089089
Author: Jeffrey O. Bennett, Seth Shostak
Publisher: PEARSON
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Textbook Question
Chapter 12, Problem 10RQ
Explain why it is reasonable to imagine optical or other signals, and the method behind current optical SETI efforts.
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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…
When Mars is 90 million km (9 x 10^10 m) from Earth, a) How long would it take for a radio wave from a video camera mounted on the back of a Mars Rover to tell ground control on earth that the Rover is about to go over a cliff? b) How long would it take for a radio signal from Earth to reach the Rover saying "STOP". c) Why do our Mars Rovers have to be "intelligent" enough to figure out how to deal with obstacles themselves?
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 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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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_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
- 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?arrow_forwardWhich 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_forwardWhen Mars is 90 million km from Earth, a) How long would it take for a radio wave from a video camera mounted on the back of a Mars Rover to tell ground control on earth that the Rover is about to go over a cliff? b) How long would it take for a radio signal from Earth to reach the Rover saying "STOP". c) Why do our Mars Rovers have to be "intelligent" enough to figure out how to deal with obstacles themselves?arrow_forward
- Why do we think we would be able to decode a message deliberately sent to us by an alien civilization? Group of answer choices The message will probably be in video format, allowing us to watch it even without knowing the alien language. We can assume that aliens will also have 10 fingers and 10 toes and therefore that they can send a message that relies on this fact. They undoubtedly have already received our television broadcasts and would therefore be likely to send the message in English. The aliens presumably know the same laws of mathematics and physics as we do and therefore could develop a simple code based on these laws.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_forwardHow can we apply the principles of Charles Darwin's theory of evolution by natural selection in our everyday life?arrow_forward
- If you detected radio signals with an average wavelength of 37 cm and suspected that they came from a civilization on a distant Earth-like exoplanet, roughly how much of a change in wavelength (in cm) should you expect to detect as a result of the orbital motion of the distant exoplanet? (Hint: Use the Doppler shift formula.) (Note: Earth's orbital velocity is 30 km/s.) cmarrow_forwardWhat is the Oobleck fee? And what are its benefits? And what are his tools? Where do we use it?arrow_forwardWhat are the three requirements that scientists believe an environment needs to supply life with in order to be considered habitable?arrow_forward
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