The Origin of the Universe

Massimiliano Galeazzi

Miami, 20 November 2002MALS 601

Summary

• The Scientific method• The view of the Universe before 1900:

•The Greeks•The Heliocentric system

• The view of the Universe after 1900:•Einstein Theory of relativity•Beyond the solar system•Hubble law

• The Big Bang theory

The Scientific Method

Observations

Theory

Predictions

Experimental verification

Philosophy

Observations

Observations

Theory

Predictions

Experimental verification

• Sun

Observations

Observations

Theory

Predictions

Experimental verification

• Sun• Moon

Observations

Observations

Theory

Predictions

Experimental verification

• Sun• Moon• Stars

Observations

Observations

Theory

Predictions

Experimental verification

• Sun• Moon• Stars

Theory

Observations

Theory

Predictions

Experimental verification

Theory 1 Theory 2

Philosophy

Geocentric theory

Observations

Theory

Predictions

Experimental verification

• Movement is not so simple

Philosophy

• The movement is not perfectly periodic

• There are monthly, annual, and longer term changes

Geocentric theory

Observations

Theory

Predictions

Experimental verification

• Movement is no so simple• Planets Mars

Philosophy

Geocentric theory

Observations

Theory

Predictions

Experimental verification

• Movement is no so simple• Planets• Distance to the objects

Philosophy

Geocentric theory

Observations

Theory

Predictions

Experimental verification

Philosophy

Ptolemy, The Almagest,A.D. c.100-c.178

Geocentric theory

Observations

Theory

Predictions

Experimental verification

Philosophy

Geocentric theory

Observations

Theory

Predictions

Experimental verification

Philosophy

EARTH

SUN

Mercury

Venus

Geocentric theory

Observations

Theory

Predictions

Experimental verification

Philosophy

EARTH

SUN

Mercury

Venus

Simplicity

“Simpler” theories

Observations

Theory

Predictions

Experimental verification

Heliocentric system: the planets (including Earth) rotate around the Sun, and the Earth is also spinning around its axisPythagoreans, Aristarchus of Samos, Plato (?), Copernicus

“Hybrid” geocentric system: the Earth is not moving, the planets rotate around the Sun that rotates around the EarthHeraclides of Pontus, Tycho Brahe

Heliocentric theory

Observations

Theory

Predictions

Experimental verification

Nicolaus Copernicus, On the Revolutions of the

Heavenly Spheres, 1473-1543

Johannes Kepler,Epitome of Copernican

Astronomy,The Harmonies of the World,

1571-1630Galileo Galilei,

Sidereus Nuncius, 1564-1642

Heliocentric theory

Observations

Theory

Predictions

Experimental verification

The phase of Venus

Observations

Theory

Predictions

Experimental verification

The phase of Venus

Observations

Theory

Predictions

Experimental verification

Galileo Galilei, c1610

Parallax

Observations

Theory

Predictions

Experimental verification

Parallaxwinter

Observations

Theory

Predictions

Experimental verification

Parallaxsummer

Observations

Theory

Predictions

Experimental verification

Parallaxsummer

Observations

Theory

Predictions

Experimental verification

1832Alpha Centauri (nearest star), Henderson

Vega, Friedrich von Struve 61 Cygni, Friedrich Bessel

Beyond the solar system

1) High concentration of stars along the milky way The stars are distributed more in a disk than in as sphere

Beyond the solar system

2) The star distribution in the milky way is asymmetric, with respect to the Earth, but is rather symmetric with respect to a

point in the constellation of Sagittarius (Shapley, 1915) The Sun is not at the center of the Galaxy

Beyond the solar system

3) There are other galaxies in the Universe in addition to ours (Hubble)

Beyond the solar system

4) There are billions of galaxies in the Universe

Solar System Galaxy Universe COSMOLOGY

Doppler effect

Doppler effect

Doppler Effect in Galaxies

Earth

MovementFast

toward usSlow

toward us

Not moving

Slowaway from us

Fastaway from us

Hubble law (redshift)

Speed = H · distance (H = Hubble constant)

Edwin Hubble1929

Observations

Theory

Predictions

Experimental verification

ALL DISTANT GALAXIES ARE RECEDING FROM US

Consequences of Hubble Law

If all the galaxies move away from us, does it mean that we are at the center of the Universe?

What happens if we rewind the tape of the Universe?

How old is the Universe?

Expansion of the Universe

If all the galaxies move away from us, does it mean that we are at the center of the Universe?

Raisin Cake

Balloon

Expansion of the Universe

What happens if we rewind the tape of the Universe?

REWIND

Age of the Universe

speed = H · distance

AGE OF THE UNIVERSE IS APRROXIMATELY THE INVERSE OF THE HUBBLE CONSTANT:

T ~ 1/H

T ~ 2 1010 years = 20,000,000,000 years

Evolution of the Universe

What happened at the beginning?

What will happen in the future?

• COLD BIG BANG

• HOT BIG BANG

Observations

Theory

Predictions

Experimental verification

The Big Bang Theory

Observations

Theory

Predictions

Experimental verification

The Big Bang Theory

Observations

Theory

Predictions

Experimental verification

The Big Bang Theory

Can we try to “see” the explosion?

YES!!!

Speed of light: 300,000 Km/s ~ 675,000,000 Miles/h

distance = 20,000,000,000 light years~100,000,000,000,000,000,000,000 Miles

Observations

Theory

Predictions

Experimental verification

The cosmic microwave background

Observations

Theory

Predictions

Experimental verification

Arno Penzias and Robert Wilson, 1965(Nobel Prize in 1978)

What will happed in the future?

What happened before the Big Bang?

?

Philosophy