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Understanding the PHYSICS of the Cosmic Times

Inquiring into the Nature of the Universe

Adapted from Dr. James LochnerUSRA & NASA/GSFC

Sandra Sweeney, Joseph PetskoPerkiomen 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 DeathEinstein’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 supernovaGiant exploding

starsCreate 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: Yerkses

Observatory (Univ Chicago)

Lowell Observatory (Flagstaff AZ)

24” Clark Telescope

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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

Hale telescope Mt Wilson CA

Keck telescope Mauna Kea, HI

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Hubble space telescope

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2 different theories of the universe’s origin:

Steady State Theory: As universe expands, matter is created; may appear unchanging Universe is eternal, stars always being made

Evolutionary 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. (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

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? The Mark 1 radio antenna constructed to

detect radio waves leftover from the Big Bang

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Spectroscopy

What is spectroscopy?

The study of light

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 R O Y G B I V

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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Tool used: 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 K residual. But they didn’t know its origin.

THE FIRST OBSERVED EVIDENCE OF THE BIG BANG

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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.

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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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, 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 energy or luminosity (brightness). Most of the galaxy’s mass is not giving off light.

E = mc2 The massive amounts of energy (brightness) must

come from some great amount of matter!!

How could 99% of the mass be MISSING!

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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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Approaching the Present

Cosmic Times 1993 and 2006

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The Universe for Breakfast - Pancake or Oatmeal??

Which describes our Universe best? 1. Pancake: smooth surface but with small

differences if you look closely 2. Oatmeal: real “lumps” like galaxies

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COBE: BABY UNIVERSE’S 1ST PICTURE

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COBE Cosmic Background Explorer COBE took better

picture of CMB (Cosmic Microwave Background)

Shows some lumpiness that will become galaxies and stars

How universe looked 380,000 yrs after BB

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What is Inflation?

Shortly after Big Bang Universe

expanded tremendously in very short time

Shows how galaxies and

stars could be formed from

CMB

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Pulars show evidence of gravitational waves (discovery wins Nobel Prize)

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Into the Darkness – Dark Matter

Matter that gives no visible light – seen with X Rays

Dark matter could slow expansion of Universe

the distribution of dark matter simulation; dark matter is clustered into halos, connected by filaments

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Cosmic Times 2006 – our time in history

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Faster Walk on the Dark Side- Dark energy is…

a mysterious anti-gravity causing universe expansion to

accelerate pushing galaxies apart creating more space

Discovered by observations of: visible light, X-ray,

radio, and microwaves

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Sorting Out Dark StuffTells what universe is composed of

4% atoms (normal matter)

23% dark matter (tugs on normal matter with gravity)

73% dark energy (flings everything apart)

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Seeds of Modern UniverseWMAP helps see structure of early Universe

WMAP: satellite launched after COBE confirms Big Bang

Gives better picture of early universe structure Shows more details of what will become galaxies

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WMAP improves CMB resolution

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Journey to Cosmos’ Dark HeartScientists are working to understand dark energy

Using new satellites (Joint Dark Energy Mission) to measure distance between galaxies

Will tell how fast galaxies have moved away are moving away

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What is Future of the Universe??

Will Dark energy rip it apart??

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Will it reach a limit and collapse, and start again??

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The end

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Cosmic Times

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

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. Impact of improved technology. Role of Women in early astronomy.

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Unsung Heroes: Women in Early Astronomy

Objectives: The students identify and describe unfamiliar scientist “heroes” that contributed to the field of science up to the year 1929.

Summary: identify the women scientists of the Harvard

College Observatory use the world wide web to complete a product

on one of the these unfamiliar scientific “heroes” that they discovered in their research.

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A print of this Harvard College Observatory photograph was found in an album that had once belonged to Annie Jump Cannon.

These women assisted Pickering in measuring stars and features on the photographic plates.

Pickering’s Harem

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Cosmic Times Posters

“Newsletter version” for individual student use

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Cosmic Times Web Site

http://cosmictimes.gsfc.nasa.gov/

1919 & 1929 Posters and Lessons now Available

This presentation is available (with links to lessons)

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