UNDERSTANDING THE UNIVERSE(LL)-W/CODE
3rd Edition
ISBN: 9780393869903
Author: PALEN
Publisher: NORTON
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Chapter 18, Problem 19QAP
To determine
The first appearance of life on the Earth.
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Check out a sample textbook solutionStudents 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.
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.
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?
Chapter 18 Solutions
UNDERSTANDING THE UNIVERSE(LL)-W/CODE
Ch. 18.1 - Prob. 18.1CYUCh. 18.2 - Prob. 18.2CYUCh. 18.3 - Prob. 18.3CYUCh. 18.4 - Prob. 18.4CYUCh. 18 - Prob. 1QAPCh. 18 - Prob. 2QAPCh. 18 - Prob. 3QAPCh. 18 - Prob. 4QAPCh. 18 - Prob. 5QAPCh. 18 - Prob. 6QAP
Ch. 18 - Prob. 7QAPCh. 18 - Prob. 8QAPCh. 18 - Prob. 9QAPCh. 18 - Prob. 10QAPCh. 18 - Prob. 11QAPCh. 18 - Prob. 12QAPCh. 18 - Prob. 13QAPCh. 18 - Prob. 14QAPCh. 18 - Prob. 15QAPCh. 18 - Prob. 16QAPCh. 18 - Prob. 17QAPCh. 18 - Prob. 18QAPCh. 18 - Prob. 19QAPCh. 18 - Prob. 20QAPCh. 18 - Prob. 21QAPCh. 18 - Prob. 22QAPCh. 18 - Prob. 23QAPCh. 18 - Prob. 24QAPCh. 18 - Prob. 25QAPCh. 18 - Prob. 26QAPCh. 18 - Prob. 27QAPCh. 18 - Prob. 28QAPCh. 18 - Prob. 29QAPCh. 18 - Prob. 30QAPCh. 18 - Prob. 31QAPCh. 18 - Prob. 32QAPCh. 18 - Prob. 33QAPCh. 18 - Prob. 34QAPCh. 18 - Prob. 35QAPCh. 18 - Prob. 36QAPCh. 18 - Prob. 37QAPCh. 18 - Prob. 38QAPCh. 18 - Prob. 41QAPCh. 18 - Prob. 42QAPCh. 18 - Prob. 43QAPCh. 18 - Prob. 44QAPCh. 18 - Prob. 45QAP
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- Calculate the numb of communicative civilizations per galaxy using your n estimates of the factors in Table 20-1.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_forwardSuppose a human generation is defined as the average time from birth to childbearing, which is about 20 years long. How many generations have passed in the 200,000 years during which anatomically modern humans have existed?arrow_forward
- 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.arrow_forwardPut 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_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_forward
- 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 Skip (you cannot come back)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_forwardwhat would happen to a life-form if the information handed down to offspring was always the same? how would that endanger the future of the life-form?arrow_forward
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