Download Cosmic Times 1955, 65 PPT

Understanding the PHYSICS of
the Cosmic Times
Inquiring into
the Nature of the Universe
Adapted from Dr. James Lochner
USRA & NASA/GSFC
Sandra Sweeney, Joseph Petsko
Perkiomen Valley School District, PA
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Understanding the PHYSICS of
the Cosmic Times 1955
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The world mourns Einstein’s Death
Einstein’s four
revolutionary
theories:
E = mc²
explains how matter can come
from energy, and vice versa
(E=energy, m=mass, c=speed of
light)
Light is not only a wave, but also
a particle
Theory of Special Relativity:
“nothing can go faster than the
speed of light”
Gravity bends space-time
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Big idea inYardsticks:
The universe is twice as big as thought : Two
Types of Cepheids!
During the wartime blackouts in California, Walter
Baade used 200” Hale telescope and discovered two
different populations of stars in Andromeda
There are two types of Cepheids, with two different
period-luminosity relationships.
Hubble had unknowingly used the wrong relationship.
Like measuring with a Yardstick when he should have used
a Meterstick
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A new type of star discovered:
the supernova
Giant exploding stars
Create heavier,
bigger elements
Elements discovered
by use of
spectroscopy
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Star life cycle: see textbook
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New Radio telescope: Earth’s
largest steerable radio antenna
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Telescopes can see all parts of the
electromagnetic spectrum
Examples of telescope types:
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Radio telescopes – capture radio waves
The Very Large Array at Socorro,
New Mexico, United States – 27 telescopes!!
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The 64 meter radio telescope at
Parkes Observatory - Australia
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Visible light telescopes: reflecting
or refracting
Refracting
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Refracting telescopes
Advantages
Easy to use
Excellent for viewing
moon, planets, binary
stars
Sealed tube protects optics
and reduces image
degrading
Rugged, need little or no
maintenance
Disadvantages
Generally small apertures, 3 to
5 inches
Tough to see small and faint
deep sky objects (distant
galaxies and nebulae)
Heavy, long and bulky
Can be expensive per inch of
aperture
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Famous refracting
‘scopes:
Lowell Observatory
(Flagstaff AZ)
24” Clark Telescope
Yerkses
Observatory (Univ
Chicago)
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Reflecting telescope
Reflecting telescopes use a huge concave parabolic mirror
instead of a lens to gather and focus the light to a flat
secondary mirror that in turn reflects the image out of an
opening at the side of the main tube. You look through an
eyepiece on the side of the tube up near the top.
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Reflecting telescopes
Advantages
Easy to use and construct
Excellent for faint deep
sky objects (galaxies,
nebulae and star clusters)
Few optical irregularities,
deliver very bright images
Reasonably compact and
portable
Costs less per inch of
aperture compared to
refractors (mirrors cheaper
than lenses)
Disadvantages
Not suited for terrestrial
applications
Some light loss when
compared with refractors
Dust can get onto optics due
to open tube even if kept
under wraps
May require more care and
maintenance
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Famous Reflecting ‘scopes
Keck telescope
Mauna Kea, HI
Hale telescope
Mt Wilson CA
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Hubble space telescope
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2 different theories of the universe’s origin:
Steady State Theory: Universe is at it has always been
Red shifted galaxies? As universe expands, matter is created; may
appear unchanging
Evolutionary Theory (a.k.a. the Big Bang theory): if we
reverse pattern of galaxies, all was concentrated in a single
point. (created everything all at once)
2 possible outcomes:
All will suck back together due to gravity and rebound,
back and forth forever
OR
Everything expands forever
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Steady State Universe
Fred Hoyle, Hermann Bondi and Thomas
Gold see the movie The Dead of Night, in
which the end of the story circles back to
its beginning.
Unchanging situations need not be static
New matter can be created spontaneously as the universe
expands (a few hundred atoms per year per galaxy)
Expansion of universe and creation of new matter balanced
via a negative energy.
The universe is constant in its overall density
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Evolutionary Universe
George Gamow worked out the conditions in the early
universe
Universe is expanding from a state of high density
and pressure.
Hydrogen & Helium were formed as universe cooled.
There should be left over a background radiation with
a temperature of ~ 5 Kelvin
Hoyle scoffed at this theory and coined the term “Big
Bang”
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What is the Evidence?
The Mark 1 radio antenna constructed to detect radio
waves leftover from the Big Bang
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Spectroscopy
The study of light
What is
spectroscopy?
Most objects in space
give off visible light
This light is captured and
analyzed with
spectroscopes
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Spectroscopy – the study of light
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Purpose of
spectroscopy:
See the element’s
“fingerprint”
coming from star
or galaxy
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Using a spectroscope, astronomers can
detect the elements in a star – can know its
life stage, temperature, movement,…
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Light Source
Colors that you see
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Try the spectroscope activities…
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Use the known element’s spectrum to
identify the unknown elements
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Recording data from a
spectroscope
Light
Source
Natural
Color
Spectrum
(colors)
Sunlight
White
ROYGBIV
Fluorescent
Hydrogen
(H)
Helium (He)
Water Vapor
(H2O)
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1965
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Show clip from 1965 CT, with “Murmur of a Bang”
and “Big Hiss”
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THE FIRST OBSERVED EVIDENCE OF THE
BIG BANG
Tool used:
Penzias and Wilson were
using a 20-foot radio antenna
to test telephone satellite
communication.
Discovered 3°K of
microwave/radio wave
energy, But they didn’t know
its origin.
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Tool for Determining
“Steady State” vs. “Big Bang”
Peebles and Dicke (Princeton) had just calculated an
estimate for the temperature (3.5º K) of the residual
background radiation from the big bang explosion, and
found it was detectable in the microwave region.
Called “cosmic background radiation”
CONCLUSION: This was strong evidence against the
Steady State theory for the Big Bang theory.
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Review of…
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Supernovae Leave Behind X Rays
X rays in space
detected with
“sounding rockets”
Atmosphere blocks
harmful X-rays
Good for us that it
does
”
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Why do we need
telescopes in
space?
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Absorption of
electromagnetic radiation
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Sco X-1
Scorpius X-1
1st extrasolar
(outside our solar
system x ray source)
In the constellation
Scorpio
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Taurus XR-1
in the Crab Nebula
1st X Ray source in
constellation Taurus
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Ophiuchus XR-1
Found in constellation
Ophiuchus (serpent
bearer)
Kepler’s supernova
from 1604
In foot of Ophiuchus
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New Problem #1 in 1965,
assuming the Big Bang to be true:
Will the universe eventually collapse back into itself,
and explode again in an endless cycle (“oscillating
universe”)
OR
Will the universe keep increasing in size forever with
each galaxy isolated in emptiness?
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Problem #2 has arisen with
improved technological
observations
Galaxies do not appear to have enough mass in them
compared to their luminosity (brightness). Where is
missing mass? (99%)
E = mc2
The massive amounts of energy (brightness) must
come from some great amount of matter!!
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Problem #3
X-rays are being detected from the universe…
But from where?
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Discovery of QUASARS
Galaxy-like objects that emit radiation that we can detect
Power of 10 trillion suns
Travel at 450 million miles/hr. (2/3 speed of light)
They have been detected nearly 14 billion light-years away.
What does this distance tell us about the age of the
universe?
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