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NATS 1880 midterm review (ch 1, 2, 3)

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Natural Science
NATS 1880
Paul Delaney

Chapter 1 Universality of the laws of science  macroscopic (multicellular) life does not exist outside of earth  microbial (bacterial) may exist outside our solar system  many stars have solar systems ∴ potential sites for life  Laws of physics work well on earth and proven to work elsewhere (universal)  Organic molecules (carbon, building blocks of life) found elsewhere o Very common o Survive harshest conditions o Do not equate to life Astrobiology  Astronomy + biology, also called “Exobiology” or “bio-astronomy” o Studies conditions conducive to origin & existence of life  Biology appreciates the tenacity and variety of life on earth o Conceivable that biological interactions can happen on other plants  Astronomy suggests that earth is not special and changes our view of earth  Planetary science helps us understand how planets behave and gives context to where to find life Importance of water and life  Liquid water is essential for life to occur  Heat or energy, time, radiation protection all needed for development and existence of life  Search for similarities in our own solar system, commonality of biology  Habitable planets have the right conditions to harbour life o Mars: had liquid water, good temp. etc o Europa (Jupiter Moon): oceans under icy surface o Titan (Saturn Moon): has lakes but is -180 degrees C o Meteorites  Milky Way galaxy is ~100k across and has more than 200 billion stars o A lot of “real estate” for life to develop SETI (search for extraterrestrial life)  SETI uses radio telescope currently used to detect life elsewhere  Varying frequencies and listening times  Ongoing since 1959 Chapter 2 Scientific method  1. observe phenomenon > 2. make a hypothesis > 3. make a prediction & devise an experiment > 4. test and publish the results > 5. reiterate (2 to 4) o unprejudiced, independent of observer, repeatable, unbiased and falsifiable o hypothesis: limited validity o model: hypotheses verified in limited circumstances o theory (law): hypotheses confirmed by multiple experiments Models of the solar system  Ancients learned sun rises in the east and sets in the west, observed motion in sky accurately  Thales: suggested universe is understandable  Anaximander: celestial sphere to understand celestial motion  Pythagoras: spherical earth (“perfect shape”)  Eratosthenes: approx. diameter of earth with accuracy  Planets move eastward but sometimes moved westward: retrograde motion  Greeks believed earth was the centre of the universe Geocentricity (sun & planets revolve around earth)  Ptolemy refined geocentric model to accurately reflect motion o predicted where planets would be in the future Heliocentricity (all planets & earth revolve around sun)  Aristarchus suggested sun was centre of universe (240BCE) o Simpler explanation to retrograde motion o Rejected; “earth was special” Early ideas of life beyond earth  Atomists thought and infinite number of particles of earth, air, fire, and water made up the universe; led by Democritus, writings showed planets “like” and “unlike” earth existed th  Aristotelians believed the 4 elements and a 5 element (the Ether) made up the universe; Aristotle said earth and its elements were unique Key scientific results  Nicholas Copernicus o Reproposed heliocentric model o Used model to determine layout of solar system o Made more sense but still used perfect circles like Ptolemaic model  Tycho Brahe o Compiled most accurate naked eye measurements (~1 arc minute) of planetary positions o Could not determine stellar parallax; thought earth was the centre of the universe but planets revolved around the sun  Johannes Kepler o Used Brahe’s data and Copernican model o 8 arc minute difference in position of Mars: ellipses orbits o 1 law of motion: planets orbit around the sun in ellipses o 2 law of motion: planets sweep out at equal times, move faster closer trdthe sun o 3 law of motion: square of orbital area = cubed of semi-major axis; p =a 3  Galileo Galilei o Aristotelian theories were wrong o Overcoming heavenly perfection with telescope; sun spots, valleys and mountains on moon; “imperfections” o Question of parallax  Showed stars were much farther than what Brahe thought  Showed Milky Way was thousands of individual stars
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