Galaxies Big Bang

Galaxies and the Universe: 

Galaxies and the Universe

What Are Galaxies?: 

What Are Galaxies? Greek galax = milk William Herschel, 1783: A disk with the Sun slightly off-center

What Are Galaxies?: 

What Are Galaxies? 19th Century: 'Spiral Nebulae' Nearby? Maybe Solar Systems in Formation? 1920: Galaxies are Stars 1920’s: Galaxies are like the Milky Way Biggest single increase in our mental picture of the Universe in human history

Where Are We in our Galaxy?: 

Where Are We in our Galaxy? The visible Milky Way suggests our galaxy is a flat disk Surrounding other galaxies is a spherical halo of Globular Star Clusters

Galaxies and Globular Clusters: 

Galaxies and Globular Clusters

The Milky Way’s Globular Clusters: 

The Milky Way’s Globular Clusters

The Milky Way As We See It: 

The Milky Way As We See It

Anatomy of a Galaxy: 

Anatomy of a Galaxy

Spiral Arms: 

Spiral Arms

In Microwaves, We Can See the Hub of the Galaxy: 

In Microwaves, We Can See the Hub of the Galaxy

Mapping the Neighborhood: 

Mapping the Neighborhood

Mapping the Neighborhood: 

Mapping the Neighborhood

Mapping the Galaxy: Not There Yet: 

Mapping the Galaxy: Not There Yet

Mapping the Galaxy: Not There Yet: 

Mapping the Galaxy: Not There Yet

The Local Group: 

The Local Group

Downtown: The Virgo Cluster: 50 m.l.y: 

Downtown: The Virgo Cluster: 50 m.l.y

The Local Super-cluster: 

The Local Super-cluster

The Coma Cluster350 m.l.y.: 

The Coma Cluster 350 m.l.y.

Large-Scale Structure of the Universe to 500 m.l.y.: 

Large-Scale Structure of the Universe to 500 m.l.y.

Travel to the Stars?: 

Travel to the Stars? Kinetic Energy = 1/2 Mv2 What does it take to get a 1000-ton spaceship to 10% of the speed of light? (43 years to Alpha Centauri) M=106 kg, v = 3 x 107 m/sec KE = 1/2 x 106 x 9 x 1014 = 4.5 x 1020 joules Equals U.S. Energy Production for 4.5 years Once you get there, you have to stop.

Relativity: 

Relativity Speed of Light is Independent of Source Michelson and Morley, 1887 - Speed of Light Independent of Observer 'One of the Most Unexpected Results in the History of Science' - Isaac Asimov Conclusion: Speed of Light is the Same for All Observers Implication: Space and Time Must Change to Keep Speed of Light Constant

Why the Speed of Light is a Speed Limit: 

Why the Speed of Light is a Speed Limit Energy of a Moving Object in Relativity: E = mc2 -------------------------------------------------------------------------------  1 - v2/c2 One consequence: as v approaches c, Energy goes to infinity Also, as we approach c, Energy goes up very fast

Slide23: 

Fuel Economy of a Starship: 

Fuel Economy of a Starship

Another Consequence of Relativity- Gravitational Lenses: 

Another Consequence of Relativity- Gravitational Lenses

“The Big Bang”: 

'The Big Bang' Edwin Hubble, Recession of Galaxies, 1929 Red-shift increases with distance Cosmic Microwave Background, 1965 Estimated Age of Universe: 12-15 b.y. 'Big Bang' originally a derisive term, coined by Fred Hoyle

As Far Out as We Can See - Ten Days With the Hubble Telescope: 

As Far Out as We Can See - Ten Days With the Hubble Telescope

A New Name for the “Big Bang?”(Sky and Telescope, 1995): 

A New Name for the 'Big Bang?' (Sky and Telescope, 1995) The Big Boot God’s Log-On Fred Withair Day ('Nobody ever named anything else after me, so why not?') What Happens If I Push This Button? You’re Never Going To Get It All Back In There Again

90% of the Universe is “Missing”: 

90% of the Universe is 'Missing' Outer Stars in Galaxies revolve faster than expected What holds clusters of galaxies together? Conclusion: There must be a lot of invisible mass in the Universe Not really 'missing', just non-luminous

Astronomers Are Not As Upset As One Might Expect: 

Astronomers Are Not As Upset As One Might Expect MACHO’s (Massive Compact Halo Objects): faint stars, brown dwarfs, planets Cool non-luminous gas Massive Neutrinos? WIMP’s (Weakly Interacting Massive Particles) Magnetic monopoles Exotic objects: strings, mini-black holes