Chapter 27

Front 1

The inhospitable caves known as Caeva De Willa Luiz in Mexico are home to bacteria which form large colonies that drip fromt eh ceilings. These colonies are called ___________.

Back 1

Snottities

Front 2

Lake Vostok is a large body of water which is located about 4,000 m below the __________ ice sheets and contains abundant life which can tolerate the extreme cold

Back 2

antarctic

Front 3

Bacteria live 3.5 km underground within the Earth's crust and gain their energy from __________ gas

Back 3

Methane

Front 4

_________, a moon of Jupiter, is hypothesized to have a liquid ocean capable of supporting life under its thich ice caps

Back 4

Europa

Front 5

SETI was the first scientific organization to look for evidence of ______________

Back 5

Extraterrestrial intelligence

Front 6

The equation formulated in the 1960's to extimate the possible number of intelligent civilizations in the Milky Way Galazy is called the _________ equation

Back 6

Drake

Front 7

Although it is currently impossible to see distant planets around other stars using telescopes, we can detect them because the planets exert a gravitational pull on the stars that they orbit. This pull causes the star to ________

Back 7

wobble

Front 8

___________ telescopes were the first type of teleschopes emplyed to look for the signals of communication from distant civilzations

Back 8

Radio

Front 9

One argument for the presence of intelligent life elsewhere in our galaxy assumes that because __________ evolved, the conditions of the universe must be suitable for intelligent life to evolve elsewhere

Back 9

Humans

Front 10

How are other planets located?

Back 10

Most astronomers are convinced that planets similar to those found in our solar system must exist in other stars but finding them is difficult. Planets outside our solar system are difficult to see due to the luminosity of the starts. Two astronomers have developed a way to determine the presence of a planet by measuring its gravitational pull on its star. This pull causes the star to wobble. This wobble can be determined by measuring the shifts in the wavelengths of the light that is emitted by the wobbling star. This is known as the Doppler Effect. Many planets have been discovered using this method, most of them similar to Jupiter and Saturn.

Front 11

Name the 4 extreme Earth environments detailed in class. For each, briefly describe the conditions found there and types of organisms present. What do these environments tell us about the possibility of life on other planets?

Back 11

1. The bacteria use the hydrogen sulfide gas as a source of energy, and sulfuric acid is produced as a by-product, making the cave environment inhospitable for other organisms. These bacteria form mucous colonies, known as snottities, hanging from the ceiling and walls of the caves.

2. These lakes are warmed by the geothermal heat produced in Earth’s mantle. Evidence of life is abundant and is rich in simple life forms. Because the glaciers above the lake were formed millions of years ago, the lake water could be as old as one million years.

3. The microorganisms present obtain their carbon source from carbonaceous materials present in the rock and they rely on methane gas that seeps from the Earth’s crust for energy.

4. This entire ecosystem of clams, tubeworms, shrimps, and other organisms is supported by bacteria that obtain energy from methane gas that seeps from the Earth’s crust. The bacteria form symbiotic relationships with clams and tubeworms. Together, they develop an extensive food web of predators and preys.



These four examples demonstrate that environmental conditions that are hostile to us (ph, pressure, temperature, energy) can still support life, as long as the basic requirements of energy, carbon source, and water are fulfilled. Based on these examples, there are many places in the solar system that might be able to support life.

Front 12

Name the two arguments that suggest intelligent life does exist somewhere in our galaxy? Describe what each argument suggests.

Back 12

Argument of scale, Anthropic argument.



The argument by scale is based the fact that there are billions of galaxies, each with billions of stars, and potential Earth-like planets). The chemistry of life is based on the most abundant elements in the universe. Because the Earth is governed by the same laws, chances, and effects, it occupies no special place in the universe). The vast universal scales of time and space make even very small probabilities of any one planet producing intelligent life an almost certainty.



The anthropic argument suggests that because humans have evolved into an intelligent civilization, then the conditions of the universe must be suitable to evolve life which can ultimately become intelligent. If intelligent life has evolved on Earth, it should and must evolve in other planets of this vast universe.

Front 13

Why do some scientist believe that life extraterrestrial life will never be found.

What is the fundamental argument for this belief and what does it have to do with the evolution of intelligence on Earth? Even if intelligent life did evolve somewhere else, what process is likely to affect its survival. What barrier exists to preclude us from communicating with extraterrestrial life if we find it?

Back 13

Some scientists think extraterrestrial life will never be found, because it does not exist.



Their arguments point toward the unlikely development of intelligent life on Earth.



Time is the most important factor in the evolution of intelligent life. Unicellular life dominated the planets over 90% of its geological time. Anatomically modern humans (humans like you and me) emerged from Africa about 200,000 years ago. Human civilization began about 10,000 years ago, and science did not become a way of acquiring knowledge until about 500 years ago. It was only in the last 100 years that science and modern technology have propelled our human society into a technologically extraterrestrial life.



Self-annihilation in a technologically-advanced civilization is highly probable.



Also, even if ETI does exist, our ability to communicate with them over vast periods of time and space will be extremely difficult. These difficulties can only be overcome if we invent time travel.