The origin and fate of the Universe.

Upper Fifth Physics

What do we see?• All of the non-local galaxies rushing away

from each other.• The further away the galaxy is the faster it

rushes away. • There’s a background radiation which is the

same (nearly) whichever direction you look.

Hubble’s Result

• A galaxy’s speed of rushing away is directly proportional to their distance.

• Near galaxies slow, distant galaxies fast.– Galaxies moving away faster appear redder. – The redder the light the faster it is. – Ask about standard candles!

What it all Means

• The universe is expanding• It started at one point.• This event is known as the ‘Big Bang’

Other Theories

• There are other theories (steady state), but none of them explain– The abundance of helium and other elements.– The cosmic background radiation.– The darkness of the Night Sky

The Fate of the Universe• This all depends on the universe’s density.• Too low and the universe expands for ever!• Too high and eventually gravity pulls everything back in

to a ‘Big Crunch’• Click the picture for more depth.

Are We Alone?

• Growing evidence for the conditions for life– Discovery of planets elsewhere in the universe– Meteorites containing ‘fossilized bacteria’– Pictures of water erosion on Mars– Water-like geology on Mars

• Passive searches of radio waves un-natural signals – the SETI project

Great links

• Loads of your questions answered at UCLA. (I still learn stuff from this…)

• SETI@home – Help search for signals from “Out There”.

• The Universe Timeline