Astronomy 100 The Beginning and End of the Universe.

Astronomy 100

The Beginning and End of the Universe

• Now: Explain the Big Bang to someone near you. Speculate: how will the Universe end?

• Goal:– Understand the basic theory of the Big Bang.– Understand that the Universe is expanding.– Understand the Big Three possibilities for the

“end” of the Universe.– Know the main evidence that supports these.

• Vocabulary: Big Bang Theory, raisin bread, Cosmic Microwave Background Radiation, Redshift, Dark Matter, Inflation, Acceleration, Dark Energy

Once Upon a Time

• There were four men: Digges, Kepler, Halley, and Olbers.

• If the Universe is infinite, why is the sky black?

• The observable universe is NOT infinite, in fact, it has a beginning. Whoa. Edgar Allen Poe was the first guy to suggest this.

Then…

• So, along comes another guy – Hubble.

• All galaxies are red-shifted (moving away from us) – and they’re red-shifted more the further away they are.

• The universe is expanding.

http://www.youtube.com/watch?v=FB0KsSrZbXY

Raisin Bread analogy

• If everything is expanding, it must have started sometime.

• The Big Bang• Happened everywhere at once• 14 Billion Years Ago

• But we need more evidence …

Along came …

• Penzias and Wilson.

• And some pigeons …

http://www.pmobs.org.au/cosmology1.html

Pigeon from Amy Ritalin:http://farm1.static.flickr.com/145/356393902_457b344514_o_d.jpg

They thought it was pigeon poop

This is actually WMAP – more detailed than what Penzias and Wilson saw.http://map.gsfc.nasa.gov/media/080997/080997_5yrFullSky_WMAP_1024W.jpg

• We’re looking back in time.• It was SUUUUUUUUUUUUPER hot. All energy.• That’s what we’re seeing – it’s about 3oK now.

• Since then the Universe has been cooling, and now we have matter instead of just energy.

Okay, so here’s the thing …

• We know the Universe is expanding, but is it – Expanding and slowing down– Expanding and speeding up, or– Expanding and staying the same?

• Two groups of people used the Hubble Telescope – they say expanding.

• WHAT ABOUT GRAVITY?

• This is (one of the places) where Einstein came in.

• He added the “Cosmological Constant” – something we currently refer to as Dark Energy. (Quintessence is another idea)

• Extra inexplicable energy that’s pushing the Universe apart.

And that’s where we are today.

• Dark Energy is confusing to us,• But this is the theory as it stands:

– 14 Billion Years ago the Big Bang happened everywhere.

– The Universe has been expanding since.– That expansion is accelerating.– Eventually we will

• … rip apart? (The Big Rip)• We don’t know yet. Chandra’s working on this.

• Answer Now: • Where is the center of the Universe?

Where is the edge?• How can we expand without a center?• What is the CMBR? Why is it important?• Define 1: Big Bang Theory, raisin bread,

Redshift, Dark Matter, Inflation, Acceleration, Dark Energy, Cosmological Constant