The (In)finite Universe

The (In)finite UniverseThe (In)finite Universe

Suketu BhavsarDirector, Kellogg Honors College

Professor of Physics

Cal State Polytechnic, Pomona

MSU Oct. 1, 2007

Questions:

What is “the universe?”

Where did it come from?

What is its fate?

What was there before it?

What lies beyond it?

Spectra:

red shifted lines = moving awayblue shifted lines = moving towards

red shift and blue shift

Hubble’s law

*The speed at which a galaxy recedes is proportional to the its distance.

The Universe is Expanding!

More questions:

Why is everything moving away from us?

(Are we special …. or do we just have bad breath?)

the raisin at the “center”

Even More questions:

Will the universe expand for ever?

What is the universe expanding into?

Expansion of the universe …two possible fates

Density of matter decides the fate of the universe

A critical density universe just “turns around”

Does size matter?

..n…..f…..i…..n…..i…..t..

or

finite

N o b o u n d a r y

boundary

What lies beyond a finite universe?

The surface of a sphere is finite but has no boundary!

Two generic varieties of curved surfaces

Positive Negative

Can something infinite be bound?

A negatively curved surface

Can something infinite at both ends be bound?

further insights …..

the ant’s universe …….

Density of matter determines curvature of space

Space retains its geometry as it expands

How does this apply to the universe we live in?

• We live in a 3-D universe.

• What gets curved?

Einstein’s theory of General Relativity

A theory of space and time

Relates gravity to the curvature of space and time, more accurately spacetime

The universe arises from the creation of space at the beginning of time

Can we know the geometry of our universe?

The Geometry of the Universe

The Geometry of the Universe

The geometry of the Universe is flat. This means the geometry you learned in high school applies over the largest distances in the universe.

How can we explain such incredible fine tuning?

Inflation

A theory that the universe expanded very rapidly at very early times

Inflation predicts a flat universe

Structure in the Universe

Observational results from CMB –kinds of matter in the universe

The content of the Universe

ordinary matter - 4%.

cold dark matter - 23%

dark energy - 73%. (One possibility is Einstein’s,

“cosmological constant.”)

The Age of the Universe with New Accuracy

– WMAP data tell us the age of our universe the margin of error is close to 1%...

–The Universe is

13.7 Billion Years Old!

Recent observations of very distant type Ia supernovae

What the distant supernovae tell us

What could make the universe accelerate!??

Einstein’s “biggest blunder”the cosmological constant

“Even when I am wrong, I am right!”