The Scale of Things

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The Scale of Things

• Lecture 3
• NATS102-13
• 9/1/09

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Announcements
Homework 1 is due now. Homework 2 will be
posted this afternoon and is due next Tuesday. I
hope that you remembered your calculators. Jupiter
is up all night. Venus is visible in the
morning, in the east. The full moon is on
September 4th. At what time will the moon rise
on Sep. 4th?
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Homework 1

• Put a checkmark next to the assertions below that
  are falsifiable (2 pts each)
• _____ The sun is at the center of the solar
  system
• _____ J. S. Bach was a better composer than W.
  A. Mozart
• _____ The Earth is getting warmer
• ______ CO2 is a bad chemical
• ______ Aliens have visited the Earth but they
  are so advanced that they are able to completely
  hide their presence.

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Horoscope Results
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If Astrology Were Exact
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Astrology is Testable, but is it Science?
Where do the rules for constructing a horoscope
come from? What are they based on? Who decided
what these rules are? What, exactly, is measured?
Can we check them to see if mistakes were
made? Received wisdom is not science the only
authorities in science are observation and
experimentation. Scientific Arguments must be
open and traceable.
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Review Characteristics of Science

• Quantitative, objective, and repeatable
  measurements
• Abstraction in a noisy Universe
• Traceability and Openness
• Falsifiable with continual attempts at
  correction.

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Power of Ten Movie

• Two ideas
• The scale of things in the Universe.
• Organizing things according to their order of
  magnitude or power of ten.

Approximate values by the closest power of 10 1.6
? 1 100 , of order one 327 ? 100 102, of
order one hundred 2,678,193 ? 1,000,000 106, of
order one million
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Show Movie
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Clicker Practice

• To within an order of magnitude, the size of an
  ant is
• 1 mm (millimeter)
• 1 cm (centimeter)
• 1 m (meter)
• 1 km (kilometer)

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More Clicker Practice

• To within an order of magnitude, the size of a
  NATS102 student is
• 1 mm (millimeter)
• 1 cm (centimeter)
• 1 m (meter)
• 1 km (kilometer)

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Even More Clicker Practice

• To within an order of magnitude, the size of the
  Earth is
• 100 km
• 1000 km
• 10,000 km
• 100,000 km
• (1 km 0.62 miles)

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Yet Again

• To within an order of magnitude, the size of the
  Sun is
• 1000 km
• 10,000 km
• 100,000 km
• 1,000,000 km
• (1 km 0.62 miles)

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What is the Universe made of?
Elementary particles Quarks (up, down, charm,
strange, top, and bottom) Basic constituents
of matter, but they normally do not exist in
isolation but combine to form other particles
such as protons and neutrons. Leptons (electrons,
muons, tauons, neutrinos) Can exists in
isolation. Each Lepton has an associated
neutrino. Gauge Bosons (photons, gluons, W and Z
bozons) Force carriers in nature.
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James Joyce. Finnegan's Wake. Book 2, Episode 4,
Page 383
Three quarks for Muster Mark! Sure he hasn't got
much of a bark And sure any he has it's all
beside the mark. But O, Wreneagle Almighty,
wouldn't un be a sky of a lark To see that old
buzzard whooping about for uns shirt in the
dark And he hunting round for uns speckled
trousers around by Palmerstown Park? Hohohoho,
moulty Mark! You're the rummest old rooster ever
flopped out of a Noah's ark And you think you're
cock of the wark. Fowls, up! Tristy's the spry
young spark That'll tread her and wed her and bed
her and red her Without ever winking the tail of
a feather And that's how that chap's going to
make his money and mark!
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Hadrons
Protons and neutrons are hadrons. They are not
elementary particles but are composed of 3 quarks
A proton is made up of 2 up quarks and 1 down
quark. A neutron is made up of 1 up quark and 2
down quarks.
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Forces Fields
A field is something that exerts a force in all
places over some region of space. An example is
the gravitational field. There are four
fundamental forces in nature Gravity,
Electromagnetic, Weak, Strong. The latter two
forces are important in the nuclei of atoms.
Gravioty and Electromegnetism are the forces felt
in everyday life. Forces are associated with the
exchange of gauge bosons on the sub-atomic scale.
For example, the electromagnetic force is
associated with exchange of photons. Scientists
are still looking for gravitons.
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Atoms
Atom - a nucleus surrounded by a cloud of
electrons. Nucleus - a pack of protons and
neutrons held together by the strong force. Each
elements is associated with a particular atom. An
atom is roughly 5?10-11 meters in diameter
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MoleculesAtoms bound together in a stable
configuration
Recently discovered in interstellar space
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Solids, Liquids, Gases
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The Earth
12,713 km
12,756 km
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The Sun
1,391,000 km
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Figure 1.7
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The Solar System
Mostly Empty Space!
1.50?1011 meters
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Alpha Centauri is 4.37 ly away
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Light Years
Light travels at 3.00?108 meters/second in a
vacuum. 1 year has 3.16?107 seconds Light travels
(3.00?108 m/s)?(3.16?107 s/y) 9.46?1015
meters/year in one year. This is a light year
(ly).
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Clicker Question

• How long does it take for light to travel from
  the Sun to the Earth?
• 1 millisecond
• 7 seconds
• 8.3 minutes
• 0.4 days

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Calculation
Start with (1.50?1011 m)/(3.00?108 m/s)
5.00?102 seconds 1 minutes 60 seconds 500
seconds (500 s)/(60 s/m) 8.3 minutes
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Figure 1.3
Interstellar Clouds (Nebula)
Orion Nebula
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Pillars of Creation
400,000,000,000,000 km or 4 light years
M16, NGC 6611, The Eagle Nebula
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Galaxies
Figure 1.4
Andromeda Galaxyour closest neighbor
200,000 light years
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Figure 1.15 Annotated
Our Galaxy (the Milky Way) as seen from
outside There are roughly 1?1011 stars in the
Milky Way.
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Chapter Opener
The Universe
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Figure 1.14 Annotated
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Figure 1.1
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Something to Ponder
Since light travels at a finite speed, we detect
light (i.e. see) events that happened some time
ago. You are seeing me move about 30 nanoseconds
later than it actually happened. The light from
we see from the sun was emitted 8 minutes ago.
When we look deep into the Universe, billions of
light years away, were seeing events that
occurred billions of years ago. The stars that
emitted the light may no longer exist. Can we
look so far away that the Universe has not yet
formed?