Origin Of The Universe-1

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Origin of the Universe

How Everything Started The Solar System The Goldilocks Planet How It Will End Points to Ponder

How It All Started: Two Theories  Steady State: 

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The Universe has always been and always will be

Inflationary -- Big Bang 

The Universe started in one vast explosion from an infinitely small point (singularity)

History of the Big Bang Theory 

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1915: Einstein formulates field equations describing space-time; arrives at a steady-state solution 1920s: Alexander Friedmann finds error in Einstein’s solution; Georges Lemaître proposes expanding universe (“cosmic egg”) 1929: Edwin Hubble discovers galaxies are moving away from each other 

The farther away a galaxy, the faster it moves

History of the Big Bang 

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1940s: George Gamow presents theory that universe started from a dense, hot state; theorizes that radiation from the big bang should still exist 1965: Arno Penzias and Robert Wilson detects by accident this leftover radiation 1970s: Alan Guth formulates currently accepted Inflationary Theory

The Big Bang 

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Not quite an explosion, but a vast sudden expansion of space No such thing as time before the Big Bang; descriptions start at 10-43 s after the event Between 10-35 and 10-32, universe expands in size by 1050 At 10-4 s, temperature is 1012°K, still no such thing yet as matter as we know it At 3 minutes after the Big Bang, things cool down enough to form atomic nuclei Elements, matter form a much, much

Stars 

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Form from gravitational accumulation and accretion of space debris (from old stars) Main source of energy: fusion of hydrogen into helium under high pressure at star’s core Larger stars have more mass, higher core pressure ⇒ burn brighter, burn out sooner

Galaxies

http://www.astro.princeton.edu/~frei/Gcat_htm/Sub_sel/gal_4731.htm

Hundreds of billions of stars, drawn together by gravity  Estimated number: several hundred billion 

http://www.astro.princeton.edu/~frei/Gcat_htm/Catalog/CJpeg/n3031.jpg

http://www.astro.princeton.edu/~frei/Gcat_htm/Sub_sel/gal_4254.htm

Star Trivia 

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Nearest Star: Proxima Centauri (4.2 light years away) No. of stars visible to naked eye in a typical sky: about 2 thousand, much fewer in Manila No. of stars in universe: 1022 Percentage of double or

More Trivia 

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Age of the Universe: ~14 B years Age of the Milky Way: ~200 MY younger than Universe Q. What’s at the edge of the Universe? A. There is no edge; space curves back on itself Stardust: Every atom in your body are remains of burned-out

The Solar System 

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Sun – averagesized star near edge of Milky Way Galaxy Planets – form with stars from space debris, but with much less mass

Planet Trivia     

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Age of the solar system: ~4.6 B yrs Distance to the Moon: 382,500 km Distance to Mars: 160 M km Distance to Pluto: 3.5 B km Planets with rings: Jupiter, Uranus, Neptune, and yes, Saturn No. of known extrasolar planets: 248 (as of 1 Aug 07 in http://exoplanet.eu) No. of planets in our solar system: 8, after Pluto’s demotion

Q. Why don’t planets crash into each other, or into the sun? A. They do, though not as often as they used to.

Earth: the Goldilocks Planet 

Just right distance from the sun; not too warm and not too cold 

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Just enough for liquid water to exist

Rotates on its axis (like a lechon) to cause even heating of the surface Axis tilted only slightly to cause seasons; too much tilt will burn up one side while the other side freezes Just big enough to hold an atmosphere, but not too big to attract too many comets and asteroids

The End of the Universe Two Possibilities  Big Crunch 

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Universe stops expanding, starts contracting due to gravity Possible if universe has enough mass (Dark Matter) After the crunch, a new Big Bang? 

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An oscillating universe?

Maximum entropy 

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All radiation and matter evenly spread out No more energy available to create stars

Points to Ponder Are we alone?

Drake Equation: N = R* × fp × ne × fl × fi × fc × L N = number of civilizations within communication range R* = rate of star formation fp = fraction with planets ne = number of those planets that can support life fl = fraction of the above that actually have life fi = fraction of the above with intelligent life fc = fraction of the

Points to Ponder 

All an Accident?

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Points to Ponder All an Accident?

Just six numbers define the properties of the universe (Rees 1999) If those numbers changed in value by a few percent, there would be no stars, no sun, no earth, no life as we know it