lecture_tan33 - Key Concepts: Lecture 33: The Big Bang! Age...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Key Concepts: Lecture 33: The Big Bang! Age of the Universe and distances from H 0 Closed, Flat and Open Universes Evidence for the Big Bang (Galactic Evolution; Microwave Background; Nucleosynthesis) Modern Theory for Galaxy Formation and Evolution Hubble’s Constant H o =70km/sec/Mpc ! o =14 billion Years Also gives us an estimate of the age of the universe Trace expansion back to size=0 Age = time of expansion = ! o = d/v = 1/H o Also, once we know H 0 this allows us to measure cosmic distances by measuring velocity from Redshift (Dopper shift) of spectral lines: v = H o d so d = v / H 0 Gravity slows down the expansion… So the age of the Universe would be less than we estimated based on constant velocities, because velocities were faster in the past. If there is enough mass (in other words if the density of the Universe is above a critical value) then perhaps the expansion can be reversed: the future of the Universe depends on this. (Like the escape speed from a planet: do the galaxies have enough speed to overcome their gravitational attraction?) Big Crunch The Geometry of Space If density > critical density Closed Universe Space curves in on itself Described by spherical geometry No parallel lines Finite (“closed”) in volume, but has no boundaries (no “edge”). Like surface of a sphere, but in 3 dimensions The Universe will turn around and collapse to “Big Crunch” If density = critical density Spatially Flat Universe (Euclidean geometry) Infinite in volume The universe expands forever, but just barely If density < critical density Open Universe Infinite in volume Easily expands forever
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
So what kind of Universe do we live in? The critical density is very small: about 9x10 -27 kg/m 3 . However, when we add up all the mass in the Universe
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 09/07/2011 for the course AST 1002 taught by Professor Dr.haywoodsmith,jr during the Spring '07 term at University of Florida.

Page1 / 5

lecture_tan33 - Key Concepts: Lecture 33: The Big Bang! Age...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online