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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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Cosmic times 1955
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Einstein’s theories
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E = mc² , which 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, which includes nothing
can go faster than the speed of light
Gravity bends space-time
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Telescopes
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Radio telescopes
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The Very Large Array at Socorro, New Mexico, United
States
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Visible light telescopes: reflecting
or refracting
Refracting
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The Refracting Telescope or Refractor
REFRACTING TELESCOPES ARE THE MOST COMMON FORM OF THE TELESCOPE - A LONG, THIN TUBE W
HERE LIGHT PASSES IN A STRAIGHT LINE FROM THE FRONT OBJECTIVE LENS DIRECTLY TO THE
EYEPIECE AT THE OPPOSITE END OF THE TUBE.
Advantages
* Easy to use and consistent due to the simplicity of design.
* Good for distant terrestrial viewing
* Excellent for lunar, planetary and binary stargazing especially with larger apertures
* Sealed tube protects optics and reduces image degrading air currents
* Rugged, need little or no maintenance
Disadvantages
* Generally have small apertures, typically 3 to 5 inches
* Less suited for viewing small and faint deep sky objects such as distant galaxies and nebulae
* Heavier, longer and bulkier than equivalent aperture reflectors and catadioptrics
* Limited practical usefulness
* Good-quality refractors cost more per inch of aperture than any other kind of telescope
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Reflecting telescope
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There are many types: Wikipedia
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The Reflecting Telescope or Reflector
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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Advantages
* Easy to use and even construct
* Excellent for faint deep sky objects such as remote galaxies, nebulae and star clusters because of their
larger apertures for light gathering.
* Low in optical irregularities and deliver very bright images
* Reasonably compact and portable
* A reflector costs the least per inch of aperture compared to refractors and catadioptrics since mirrors can
be produced at less cost than lenses
Disadvantages
* Generally, not suited for terrestrial applications
* Slight light loss due to secondary obstruction when compared with refractors
* The tube is open to the air, which means dust on the optics even if the tube is kept under wraps
* Reflectors may require a little more care and maintenance
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The universe is twice as big as
thought : Two Types of Cepheids!
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During the wartime blackouts in California, Walter
Baade discovered two different populations of stars in
Andromeda
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Used 200 inch telecscope
This led to realizing there are two types of Cepheids,
with two different period-luminosity relationships.
Hubble had unknowingly used the wrong relationship.
Yardstick vs Metersticks
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[show clip of 1955 Cosmic Times showing “Origin of
Everything” article ?]
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Is Universe a “Steady State” or
Did it originate from a “Big Bang?”
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Steady State Theory: As universe expands, matter is created.
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Evolution Theory (a.k.a. the Big Bang theory): running
expansion backwards leads us to a point of high density and
high temperature from which universe originated. (Create
everything all at once)
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All will suck back together due to gravity and rebound, back and
forth forever
OR
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Everything will continue to expand outward
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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.
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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
Starting from earlier work, George Gamow & Ralph
Alpher 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 for Big Bang?
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Leftover heat from explosion (3.5 degrees Kelvin)
The Mark 1 radio antenna constructed to detect radio
waves leftover from the Big Bang
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A new type of star discovered:
the supernova
 Giant
exploding stars
 They create heavier, bigger
elements
 Elements discovered by use of
spectroscopy
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Star life cycle: see textbook
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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:
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Penzias and Wilson were
using a 20-foot horn detector
to test satellite
communication.
Effort to reduce fuzz/hiss in
the detector left them with a
3 degrees K residual. 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”
 Peebles and Dicke were convinced that Penzias and
Wilson had found it.
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This was strong evidence against the Steady State
model of the universe and for the Big Bang theory.
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Review of…
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New Problem #1, assuming the Big
Bang to be true:
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Will the universe eventually collapse back into itself,
and explode again in an endless cycle (“oscillating
universe”)
OR
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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). Most of
the galaxy’s mass is not giving off light.
How could 99% of the mass be MISSING!?
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Problem #3
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X-rays are being detected from the universe…
But from where?
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Discovery of QUASARS
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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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Cosmic Times
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1919 - Confirmation of Einstein’s Theory of Gravity
1929 - Hubble’s discovery of Expanding Universe
1955 - Debate between Big Bang and Steady State
1965 - Discovery of the Cosmic Microwave
Background
1993 - COBE Results; Development of Inflation
Theory
2006 - Grappling with Dark Energy.
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Cosmic Times: Scientific Themes
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Our understanding of the Expansion of the Universe
Nature of Supernovae
The size and scale of the Universe
A number of other themes also appear.
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Impact of improved technology.
Role of Women in early astronomy.
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