Galaxies and the Universe

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

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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.

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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

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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

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Fuel Economy of a Starship

At 0.1 c, energy is 0.7% greater than Newtonian formula

At 0.5 c, 24% greater

At 0.9 c, 3 x greater

At 0.99 c, 12 x greater

At 0.999 c, 43 x greater

Each extra 9 more than triples the energy

Getting our 1000 ton ship to 0.9 c takes 1.1 x 1023 joules = U.S. energy use for 1100 years

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Another Consequence of Relativity- Gravitational Lenses

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What Does The Universe Look Like?

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What Does The Universe Look Like?

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“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

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

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