How Big is the Universe?
Really big!The Sun is 8 light minutes away.
There are 1011 stars in our galaxy.
COBE/DIRBE satellite image
The center of our Galaxy is 25,000 light years away.
The Milky Way in infrared emission.
The Universe is ExpandingHubble observed that the further away a galaxy is the faster it is moving away.
Us Galaxy
We are not (that!) special, all observers see the same. A neighbor
We should think about this as “making space” since the Big Bang, not as an explosion in a preexisting space. The Universe appears the same from all vantages.
The Universe is Infinite. We live in a “Hubble Patch”
Diameter set by:
2 (speed of light) x (age of universe)
Observable Universe or Hubble Patch
“Edge” of the observable universe
Ignore the expansion and imagine being able to go anywhere in the “whole universe” instantaneously
Because the Speed of Light is Finite, Telescopes Are Like Time Machines
We see distant objects as they were when they were younger.
“Edge” of the observable universe
Still ignoring the expansion
Younger
Now Add The Expansion
Light from the “edge” was emitted when the universe was much more compact.
The expansion of space stretches wavelengths.
“Edge” of the observable universe
Younger
Decoupling of the CMB
The universe expands and cools from its fiery beginning.
When the temperature of the Universe is roughly half the temperature of the Sun, atoms of hydrogen can form.
This is called the epoch of decoupling and it occurred 379,000 years after the Big Bang.
-e
-e -e-e
Neutral atomsIonized
plasma
Universe cools CMBproton
How Do We Measure the CMB?
With the expansion of the universe, the CMB has cooled to -270 oC, or 2.725 oC above absolute zero.
The CMB is about 1000 times cooler than the Sun and so “shines” in the microwave regime.
TV Channel 69 broadcasts at 800 MHz
CMB approx 1% of TV noise!
You’ve all detected the CMB!
UBCMark Halpern
JPLOlivier Dore
NASA/GSFCBob Hill Gary Hinshaw Al KogutNils OdegardJanet WeilandEd Wollack
PrincetonNorm Jarosik Lyman PageKendrick SmithDavid Spergel
ChicagoStephan MeyerHiranya Peiris
BrownGreg Tucker
UCLANed Wright
Science Team:
WMAPA partnership between NASA/GSFC and Princeton
Johns HopkinsChuck Bennett (PI)Ben GoldDavid Larson
CornellRachel Bean
MicrosoftChris Barnes
CITAMike Nolta
ICELicia Verde
UT AustinEiichiro Komatsu
OxfordJo Dunkley
ColumbiaMichele Limon
How do we get hot and cold patches?
Gravitational landscape--just like hills and valleys.
ColderColder
Hotter
Spot size = [speed plasma ( ) travels]x[age of universe at decoupling]
1 degree in angle
W. Hu
The “fundamental mode” acts as a fundamental “footprint” or yardstick at the edge of the observable universe.
This allows us to determine the size of the observable universe.
Us
(12,000 stacked hot spots.)
deg
Cosmic Paleontology
From the standard yardstick, we can deduce the distance to the edge of the universe.
Knowing this distance, and the speed of light, we deduce that the age of the universe is:
tU=13.75 +/- 0.13 Gyr
Basic model (with only six parameters) agrees with virtually all cosmological measurements.
Parameters of the Model
4.6%22.6% 72.8%
The “dark energy” has no foundation in any fundamental theory of nature.
It is as though the vacuum has an energy associated with it that drives the universe apart, like antigravity.
Most feel that “dark energy” represents a missing piece of theory as opposed to a substance.
The Standard Cosmological ModelAt a very early time a “quantum field” impressed on the universe a gravitational landscape. We measure characteristics of this field.
Abbreviated
This is a picture of a quantum field from the birth of the universe.
Matter fell into the valleys to form eventually “structure.” But only 1/6 of this matter is familiar to us.
The dynamics of the universe is now driven not so much by the matter but by an apparent
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