Life in the universe-Chapter 1 Notes PDF

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Life in the universe (Book notes)

Chapter 1.1- KEY NOTES  Possibility of life beyond earth = aliens  Scientists remain deeply skeptical about reports on aliens on Earth. They are searching for life elsewhere, looking for evidence on Solar Systems.  Scanning planets orbiting stars & signals broadcast by other civilizations.  E.T. discovery = discovery of life beyond earth and changes perspective on how we fit into the universe as a whole & teaches us more about life on earth.  Are still looking for E.T. that look like bacteria-like-microbes, plants/animals in parks and zoos, fictional characters in TV shows and movies or something completely different.  Searching for any life (simple, intelligent, different or complex) is hard since we cannot define life. Due to definitional difficulty, we search for life like Earth.  Have enough scientific tools like telescopes and spacecraft’s to know that NO civilizations ever existed on Mars or Venus.  KEY POINTS: 1) Although muli-cellular organisms are found only on earth, studies of planetary science & biology make it plausible for tiny microbes to exist on other planets. 2) Recently gained concrete evidence that more planets exist in the Solar System (meaning more places to look for life). 3) Advances in technology and scientific understanding make it possible to study the question of life in the Universe with established techniques of science.

CHAPTER 1.2- KEY NOTES  Scientific Context of Search = biology, astronomy, planetary science( includes geology & atmospheric science)  Astronomy- provides context to the search for life in many ways- especially by studying distant objects, we learned that the physical laws that are applied here on Earth are the same throughout the universe, meaning what happens on Earth, could’ve happened somewhere else.  Astronomical context makes it clear that the universe holds an enormous number of stars that could potentially be orbited by planets with life.  Planetary science- study of planets and the objects surrounding planets like asteroids and comets. It also helps set the context in several different ways.

1) By learning how planets form, we develop an understanding of how common we might expect planets to be. = In 1995, strong evidence of extrasolar planets was obtained and since then, the number of extrasolar planets exceeds the number of planets in our solar system. 2) Helping us understand how planets differ. = Rocky planets (Earth) VS Gaseous planets (Jupiter). Have a good idea as to why Mars was warmer/wetter in the past VS today where it is dry/cold.  Habitable worlds- worlds that have the same ingredients and conditions necessary for life. (Environmental conditions under which, life could arise or survive, not whether it actually harbors life.)  Planetary science- suggests that most stars have planets that could be potential homes.  Key question- Biological context of the search revolves around whether we should expect biology to be rare or common in the universe.  Galaxies sprinkled, stellar processes, orbital motions, law of gravity = basic laws of physics discovered in the universe.  Star observations tell us they are made up of the same chemical elements that are found on earth, and that interstellar gas clouds contain many of the same molecules on earth = basic laws of chemistry  Laboratory experiments tell us that chemical constituents found on early earth, would have combined with organic carbon-based molecules (building blocks of life), which were found in meteorites through spectroscopy in clouds of gas between stars.  Biology could be common- microscopic life can survive harsh conditions like life exists near extremely hot water near deep-sea volcanic vents, inside rocks & frigid conditions of Antarctica.  Biology suggests 3 lines of evidence that might be common on other habitable planets: 1) The fact that life arose on quickly on earth suggests that it might occur on any world that has the “right” conditions. 2) We know from observations of meteorites and interstellar clouds that organic molecules are common throughout the galaxy, suggesting we will find many worlds. 3) Some life on earth survives even seemingly extreme conditions suggests that life is hard enough to survive in other places.

CHAPTER 1.3- KEY NOTES  Places to Search  Best place to search is on Earth, because the more we know about life on Earth, the better we can search for it elsewhere. The next place is to search our Solar system and dwarf planets.  Mars has significant amounts of ice water, and strong evidence tells that the now barren surface of Mars, once had flowing water.  Some of the moons are the most promising abodes for life including- Jupiter’s moons (Europa- hides a deep ocean of liquid water under its icy crust, Ganymede & Callisto- show some evidence (weak) for sub-surface oceans). Other candidates include Saturn’s moon (Titan- has a thick atmosphere of lakes of liquid methane, and Enceladus, appearing to have sub-surface ocean from which we see fountains of ice spraying out into space)  Telescopes are the only hope for researching extrasolar planets that are too far for humans to travel to. Current extrasolar technology can detect extrasolar planets under certain conditions.  Aliens or intelligent life could be searching for us. If life is common in the universe, civilizations could be sending their own signals and searches of their existence. However, we have a telescope that specifically search’s for E.T life.  *SETI- SEARCHING FOR EXTRATERRESTRIAL INTELLIGENCEfocuses on searching for such signals from alien civilizations.

CHAPTER 1.4- KEY NOTES  The new science of Astrobiology  Astrobiology- the study of life in the universe  Research is focused on 3 main areas: 1) Studying the conditions conductive to the origin and ongoing existence of life 2) Looking for such conditions on other planets in our solar system and around other stars 3) Looking for the actual occurrence of life elsewhere  Astrobiology research seeks to reveal the connections between living organisms and the places where they reside....