Our Universe in Time

(intro survey)

Everything's moving!

From studying these motions “we” find ….

• Our universe is expanding – and hence has a history

• We don’t know what most of the matter in it is!

How are we moving through space?

Earth spins on it’s axis!

Period: 1 day

Speed: 1670 km/hr (@ eq.)

Earth Orbits sun!

Period: 1 year Average speed: 107,000 km/hr

(relative to sun)

Sun’s motion within the galaxy!

PROBLEM

Matter-Energy in the universe

Motion within the Local Group!

~360,000 km/hr

Crash in 3 to 5 billion years

This illustration shows a stage in the predicted merger between our Milky Way galaxy and the neighboring Andromeda galaxy, as it will unfold over the next several billion years. In this image, representing Earth's night sky in 3.75 billion years, Andromeda (left) fills the field of view and begins to distort the Milky Way with tidal pull. (Credit: NASA; ESA; Z. Levay and R. van der Marel, STScI; T. Hallas; and A. Mellinger)

Motion at the Cosmic scale!

Is it just US?Is it something we said?

The Basic assumptions of cosmology:• Universe is isotropic

• Universe is homogenous

Expanding Universe

0 321 4 765-1-2

Expanding Universe

0 321 4 765-1-2

(1 hour later)

Positionbefore

Positionafter

apparentspeed

t

d

Galaxy

-1 ly

+1 ly

+2 ly

+3 ly

-2 ly

+2 ly

+4 ly

+6 ly

-1 ly/hr

+1 ly/hr

+2 ly/hr

+3 ly/hr

Relative to yellow galaxy

0 321 4 765-1-2

Current position (ly)

Relative speed (ly/hr)

-1

1

2

3

4

Mpc

km/s700 H

In a length of the universe 3.3 Mly long, 70 km of ‘new space’ is

added each second.

EXPANSION A BEGINNING

( ~ 14 billion years ago )

Tricky: Universe hasn’t always

expanded at the same rate

TIME = ~ 0

The Early Universe

Really hot and really dense

Hydrogen and Helium

~ 380,000 years

Where do we come from ?

Hydrogen and Helium

~ 400,000 yearsFirst Stars & Galaxies

(H and He)

Stellar recyling

Gas and dust

Star “lives”

Star “dies”

(Mostly H and He)

Stellar fusion creates heavier

elements: notably Oxygen and

Carbon!

Stellar recyling

Gas and dust

Star “lives”

Star “dies”

(Mostly H and He)

Stellar fusion creates heavier

elements: notably Oxygen and

Carbon!

Returns the ‘common’ light elements:

i.e. carbon, nitrogen, silicon, iron

Returns the rarer, heavy elements:

i.e. gold