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-14 TH 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 18 th century (1765) century and 19 • Able to get power from steam th • 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 19 th 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 1 st 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 • 1 = 1 5 = 101 6 = 110 10 = 1010 15 = 1111 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 WWII ENIGMA • 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

• 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 • The light is very

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.

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 "half silvered," 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

distributed in a solid matrix (such as the ruby or neodymium:yttrium-aluminum garnet "Yag" lasers). have lasing material

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

some laser printers or , 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 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

4.

5.

6.

7.

What kinds of things use laser technology?

1.

2.

3.

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