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Computer Science 129
Science, Computing and Society
Week 3
Chapter 2
1
GRE/GMAT WORDS
• Pedant - person who orveremphasizes
rules and details, makes excessive display
of learning
• Vacillate – to waver or to be indecisive
• Capricious – subject to a whim, erratic
• Engender – to cause
2
GRE/GMAT WORDS
REGARDLESS
-adjective 1.having or showing no regard;
heedless; unmindful (often fol. by of).
–adverb 2.without concern as to advice,
warning, hardship, etc.; anyway: I must
make the decision regardless.
THERE IS NO SUCH WORD AS
IRREGARDLESS
3
Chapter 2
Machines and Metaphors
• Metaphor
– A figure of speech in which a word or phrase
that ordinarily designates one thing is used to
designate another, thus making an implicit
comparison, as in “a sea of troubles”
4
Chapter 2
SUPERPARADIGMS
• Point of view about what is fundamental in
determining what happens in the world
• Driving forces for history of modern
science
5
Chapter 2
SUPERPARADIGMS
• Clock
• Steam Engine
• Computer
All have inspired frameworks for science
6
Chapter 2
CLOCKS-14TH century we see weight driven
clocks
• Described the universe in terms of motion
governed by Force like moving parts of
weight driven mechanical clock
• Metaphor for scientific worldview based on
FORCE
• All of science was focused on force
7
Chapter 2
STEAM ENGINE
• Huge in end of 18th century and 19th
century (1765)
• Able to get power from steam
• Watt style steam engines largest source of
power in industrial England
• Pumping water out of mines
• Driving flour and textile mills
8
Chapter 2
• By the 19th Century, the Steam Engine
became driving force in transportation
• Became symbol of Industrial Revolution
• Metaphor for scientific worldview based on
ENERGY
• All of science began thinking in terms
of energy
9
Chapter 2
COMPUTER
• Fight over who actually invented the
computer
• Charles Babbage created 1st Analytical
Engine
• Metaphor for scientific worldview based on
INFORMATION
• All aspects of science and society are
focused on information
10
Chapter 2
• COMPUTERS USE BOOLEAN LOGIC
• BASE 2
• USES 0’s AND 1’s
11
Chapter 2
COUNTING IN BASE 2 = POSITIONAL
NOTATION WITH A RADIX OF 2
• 0 = 0 5 = 101 10 = 1010 15 = 1111
• 1 = 1 6 = 110 11 = 1011 16 = 10000
• 2 = 10 7 = 111 12 = 1100 17 = 10001
• 3 = 11 8 = 1000 13 = 1101 18 = 10010
• 4 =100 9 = 1001 14 = 1110 19 = 10011
12
Chapter 2
• When counting in base 2 you count up starting
at zero and only use numbers that only contain a
0 or a 1.
• 0,1, then you must skip 2,3,4,5,6,7,8 and 9
because they use a number other than 0 or 1.
The next usable number is 10, then 11, then
100. The number 12-99 all use numbers other
than 0 and 1. Study the table on the previous
slide. You will need to be able to count to 10 in
base 2 for the midterm.
13
Chapter 2
ALAN TURNING – 1930’s – USED
BOOLEAN LOGIC
• Cracked German secret code in WWIIENIGMA
• Analyzed Physics of pattern formation
• Turing Test
• Determined how, in theory, digital
computers work
14
Chapter 2
The Turing Test
• Called Imitation Game
• Used to test a machine to determine if the
machine is “intelligent”
• Measures the performance of a machine
against that of a human being
15
Chapter 2
How The Turing Test Works
• Machine and human placed in 2 rooms
• Another person (the interrogator) is in a third
room and cannot directly communicate with
other person or machine
• The interrogator asks questions of the
machine and person questions via a text
terminal
16
Chapter 2
• Based on the answers given, the
interrogator must try to distinguish
between person & machine
• If the interrogator cannot distinguish the
two, the machine is assumed to be
intelligent
17
Chapter 2
• You can ask any type of question. What
the interrogator is looking for is the human
answer…not the right answer.
• What is ultimately tested is how good the
programmer is…whether or not they wrote
a good program to respond to the
interrogator.
• This was the beginning of artificial
intelligence.
18
Chapter 2
• ARTIFICIAL INTELLIGENCE
– a system that perceives its environment and
takes actions which maximize its chances of
success
– EXAMPLES:
• Chess games
• Facial recognition software
• Fingerprint analysis
19
Chapter 2
TURING MACHINE
• Turing Machine is like a typewriter
• He wanted to find a machine that, using
some guaranteed method, could figure out
anything
• This method needs a set of specific
instructions (called algorithm)
20
Chapter 2
• This device needed a few things
– To read long strip of paper
– To write on paper (long strips divided into
squares)
– An erasing key to remove existing marks on
square
– Paper can move forward & backwards one
square
– Be able to change states
21
Chapter 2
• Think of states like your keyboard. There is a
set of instructions for each key and that would
be one state
• When you hold down the shift key, there are a
whole new set of instructions for the keys. This
would be another state.
• The machine could have an infinite number of
states…or an infinite number of sets of
instructions.
22
Lasers
from howstuffworks.com
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•
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•
CD players
DVD players
Dental drills
High speed metal cutting machines
Tattoo removal
Scar removal
Skin resurfacing (for wrinkles and discoloration)
Hair replacement
Eye surgery
23
Lasers
•
•
•
•
How are they different from a flashlight?
Lets look at the atom
Only 110 different kinds of atoms in the universe
Everything we see is made up of these 110
atoms in an unlimited number of combinations.
• How these atoms are arranged and bonded
together determines whether the atoms make up
a cup of water, a piece of metal, or the fizz that
comes out of your soda can!
24
Lasers
• Atoms have a nucleus made up of protons
and neutrons and an electron cloud with
electrons.
25
Lasers
• Atoms are in constant motion-BROWNIAN
MOTION
• Atoms can be in different states of excitation.
In other words, they can have different energies
• If we apply a lot of energy to an atom, it can
leave what is called the ground-state energy
level and go to an excited level. The level of
excitation depends on the amount of energy that
is applied to the atom via heat, light or electricity
26
Lasers
• When energy is applied, the electrons
move away from the nucleus from lower
energy orbitals to higher energy orbitals
• When the electron returns to the lower
energy orbital, it releases it’s energy as a
photon, or a particle of light
• All light is due to electrons changing orbits
and releasing photons
27
Lasers
• A laser is a device that controls the way
that energized atoms release photons.
• "Laser" is an acronym for light
amplification by stimulated emission of
radiation, which describes very succinctly
how a laser works
28
Lasers
• Typically, very intense flashes of light or
electrical discharges pump the lasing medium
and create a large collection of excited-state
atoms
• It is necessary to have a large collection of
atoms in the excited state for the laser to work
efficiently.
• In general, the atoms are excited to a level that
is two or three levels above the ground state.
29
Lasers
• Once excited, the electron can simply
relax, and in turn rid itself of some energy.
This emitted energy comes in the form of
photons (light energy).
30
Lasers
• The photon emitted has a very specific
wavelength (color) that depends on the
state of the electron's energy when the
photon is released.
• Two identical atoms with electrons in
identical states will release photons with
identical wavelengths.
31
Lasers
Laser Light has the following properties:
• Laser light is very different from normal light. The light
released is monochromatic. It contains one specific
wavelength of light (one specific color). The wavelength
of light is determined by the amount of energy released
when the electron drops to a lower orbit.
• The light released is coherent. It is “organized” -- each
photon moves in step with the others. This means that all
of the photons have wave fronts that launch in unison.
• The light is very directional. A laser light has a very tight
beam and is very strong and concentrated. A flashlight,
on the other hand, releases light in many directions, and
the light is very weak and diffuse.
32
Lasers
• To make these three properties occur
takes something called stimulated
emission. This does not occur in your
ordinary flashlight -- in a flashlight, all of
the atoms release their photons randomly.
• In stimulated emission, photon emission is
organized.
33
Lasers
• The other key to a laser is a pair of mirrors, one
at each end of the lasing medium.
• Photons, with a very specific wavelength and
phase, reflect off the mirrors to travel back and
forth through the lasing medium.
• In the process, they stimulate other electrons to
make the downward energy jump and can cause
the emission of more photons of the same
wavelength and phase.
34
Lasers
• A cascade effect occurs, and soon we
have propagated many, many photons of
the same wavelength and phase.
• The mirror at one end of the laser is "halfsilvered," meaning it reflects some light
and lets some light through.
• The light that makes it through is the laser
light.
35
Lasers
• There are many different types of lasers.
• The laser medium can be a solid, gas,
liquid or semiconductor.
• Lasers are commonly designated by the
type of lasing material employed
36
Lasers
Laser Types
• Solid-state lasers have lasing material
distributed in a solid matrix (such as the ruby or
neodymium:yttrium-aluminum garnet "Yag"
lasers).
• Gas lasers (helium and helium-neon, HeNe, are
the most common gas lasers) have a primary
output of visible red light. CO2 lasers emit
energy in the far-infrared, and are used for
cutting hard materials.
37
Lasers
• Excimer lasers (the name is derived from the terms
excited and dimers) use reactive gases, such as chlorine
and fluorine, mixed with inert gases such as argon,
krypton or xenon. When lased, the dimer produces light
in the ultraviolet range.
• Dye lasers use complex organic dyes, such as
rhodamine 6G, in liquid solution or suspension as lasing
media. They are tunable over a broad range of
wavelengths.
• Semiconductor lasers, sometimes called diode lasers,
are not solid-state lasers. These electronic devices are
generally very small and use low power. They may be
built into larger arrays, such as the writing source in
some laser printers or CD players.
38
What You Should Know
NAME THE 3 SUPERPARADIGMS OF THE
LAST THOUSAND YEARS.
1.
2.
3.
39
What You Should Know
SUPERPARADIGM
Metaphor for Scientific
World View
40
What You Should Know
• BE ABLE TO COUNT TO 16 IN BASE 2.
41
What You Should Know
What Requirements Did Turing Have For
His Computational Machine?
1.
2.
3.
4.
5.
42
What You Should Know
SHORT ESSAY:
EXPLAIN HOW A TURING MACHINE
WORKS. INCLUDE INFORMATION
ABOUT STATES.
43
What You Should Know
SHORT ESSAY:
EXPLAIN HOW THE TURING TEST
WORKS AND WHAT IS DETERMINED
FROM THE OUTCOME.
44
What You Should Know
What kinds of things use laser technology?
1.
2.
3.
4.
5.
6.
7.
8.
9.
45
What You Should Know
How many types of atoms are there in the
universe?
What two regions make up an atom?
1.
2.
46
What You Should Know
What do you find in the nucleus of an atom?
1.
2.
What do you find in the electron cloud of an
atom?
1.
47
What You Should Know
Describe an atom’s different states of
excitation
48
What You Should Know
Describe how light is emitted in a laser (how
is a laser created).
49
What You Should Know
What is the word laser an acronym for?
50
What You Should Know
What three properties does laser light have?
51
What You Should Know
What is required for the three properties of a
laser light to occur.
52
What You Should Know
What types of medium can be used to
create a laser?
1.
2.
3.
4.
53
What You Should Know
What are the 5 different types of lasers?
1.
2.
3.
4.
5.
54