The expanding universe
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Transcript The expanding universe
Section 7.3
THE EXPANDING UNIVERSE
Hubble’s Ideas...
____________________________(1889-1953)
An American astronomer
One of the first to study _______________
Two of his major findings changed astronomy (1918-1929)
1. Confirmed many other galaxies existed beyond the
_________________________
2. Found that almost all galaxies are _________________
from each other
This meant that the universe is _____________________!!
(this was stated by a man named _________________)
But how?
How did Hubble do this?
Measured the distance from Earth of _____________
Measured the _____________of their movement
Collected light from the galaxies and examined their
__________________________ (spectra)
____________________________________: the rainbow
band of colours into which white light separates when it
passes through a prism
Hubble’s work and ideas remain the foundation
of modern understanding of the nature and
origin of the universe
The REAL Big Bang Theory
What is it?
One of the most remarkable theories of the 20th
century
_____________________________________________
_____________________________________________
_____________________________________________
_____________________________________________
_____________________________________________
NO _______________________________!!
All matter and energy today was created during the
early minutes of the hot, rapid expansion
Credited to George Gamow and Ralph Alpher
Evidence for the BBT
Commonly accepted that universe formed
________________________ years ago
______________of universe and SPACE and TIME!!
What Hubble saw:
Looking at light spectra, figured out each galaxy’s
speed moving away from ours
He saw that the _______________________ the
galaxy was, the ____________it was moving away
Loads of “light” elements (H and He)
The Wave Nature of Light
_____________________________: energy that
travels in waves of varying lengths
E.g.: light, radio waves, microwaves, ultraviolet
radiation, X-rays
__________________is E.R. we can see with our eyes
When it is split into a rainbow of colours, it’s called the
_______________________________________
Electromagnetic Spectrum
Full range of E.R. organized by wavelength from very
long to very short
The Wave Nature of Light
Wavelength of _________ light is longer than the
wavelength for ___________light
Spectroscope
This is an optical instrument that separates
_____________ into its spectral colours
Helps astronomers analyse star light
The Wave Nature of Light
•Spectral
Lines
• Look like a
UPC/bar code
• Created when
each gas that
makes up a
star absorbs
some of the
light energy
• Each gas does
this differently,
creating different
lines
•We can see the spectral
lines of H in the spectra
of almost all celestial
objects, meaning H is
present throughout the
universe
Red-Shifted Spectral Lines
___________________________
The change in position of spectral lines to the left
or right of where they normally are in the
spectrum of a light source that is not moving
Astronomers noticed that in all galaxies Hubble was
studying, spectral lines were shifted to the ________
This meant that the light source and observer are
________________________ from each other at a high
speed!!
Picture the Waves...
a) In this picture, the
duck sits still, creating
even ripples on the
water
b) As the ducks starts
swimming, ripples
behind stretch out
(wavelength is longer)
c) This is how Hubble
knew galaxies were
moving away from
earth (expanding); he
measured light
wavelengths emitted
from a galaxy to see if
and where it was
moving
Seeing Shorter VS Longer
Wavelengths
Red-Shifted Spectral Lines
Hubble saw this _________________ pattern
in many galaxies
Gave support to theory that space was
_____________________________!
_____________________ telescope in Hawaii
repeated Hubble’s work with 60 000 galaxies
instead of 46
Added to Hubble’s work
Learning Checkpoint
1. What is a spectrum?
2. What is the name given to the generally
accepted scientific theory that describes the
origin and evolution of the universe?
3. How is it possible to know that the element
hydrogen exists throughout the universe?
4. How does the idea that space itself is
expanding relate to the observation that the
spectra from distant galaxies are red-shifted?
Using Microwaves to Map
Cosmic Background Radiation
Critical question related to BBT:
__________________________________________
_________________________________________?
First bit of universe was HOT with short waves
Then universe cooled and waves lengthened
where did the extra energy go?
All space should have evidence of this
__________________________
More Evidence for BBT
____ Arno Penzias and Robert Wilson made
the big discovery (_________________________)
_________________________________________
Energy left over from the massive split-sec expansion
______________________ Radiation Maps
Maps of cosmic background radiation collected from
most distant parts of visible universe
CBR found fits with predictions consistent with BBT