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
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(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
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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
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