Quick lecture for high school students to get them excited about CS>

1. Computer Science = ideas
Ideas are powerful.
You up for it?
tim@menzies.us
Oct’12

2. Don’t say you were not warned
• If you want knowledge: bite the apple.
– Welcome to responsibility and shame.
• Make a choice
– Take charge
– Leave paradise
• Would you want it any other way?
– If Eden then no sex
– no anesthetics (anyone you know had a baby? had a tooth pulled?)
– no air travel (no spring break in Miami)
– no space program (we landed on Mars? wow)
– no internet, no smart phones, no Xbox
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3. Case study 1
How computers won WW-II

4. Convoys, sunk by U-boats
The enigma
machine
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5. Enter computers
• Bletchley Park,
England
• Massive banks
of computers
– looking for
patterns in
German radio
signals
• Massive kludgey machines
– run by an army of 10,000 woman
– Winston Churchill: “The geese that laid the golden eggs
- but never cackled.”
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6. The programmer
• Alan Turing:
mathematical genius
– Defined what it means
to be computable.
• By the way, he was gay
– we’ll get back to that.
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7. The curse of information
The power The shame
• Thanks to Turing, • So they had to let (some)
– the allies knew the location of boats get sunk and (some)
the U-boats bombs fall on England
• But they had to be careful – In order to mount the
– If the Germans knew they invasion and win the war
knew, they change the codes • Dead sailors
– Take years to break the new • Dead civilians
ones
• Bletchley Park hastily
dismantled post-WW2,
records quickly forgotten
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8. Case study #2
Computers and hydrogen bombs
were developed by the same people
at the same time for same reason

9. How to build a thermo-nuclear bomb
(don’t try this at home)
1. separation of stages into a
triggering "primary" explosive and
a much more powerful
2. "secondary" explosive, compression
of the secondary by X-rays coming
from nuclear fission in the primary,
a process called the "radiation
implosion" of the secondary,
3. heating of the secondary, after cold
compression, by a second fission
explosion inside the secondary.
Btw,
All in a microsecond
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10. Enter computers
• To design "radiation
implosion"
– Need massive simulations
• Enter the king of
the shock wave
– John Von Neumann
• Built computers at Princeton
– using Turing’s designs
– Ran the sims
– Built the bombs
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11. His favorite computer programmer
• His wife, Klara von Neumann
– Famous ballerina
– Bored by her first husband (a banker)
– Left him for Johnny, moved to
America
• Gifted
– While Johnny wined and dined the
generals
– She ran the clunky computers back at
Princeton
• Did not do well when Johnny died
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12. The curse of information
The power The shame
• Thanks to Von Nuemann, • Global annihilation
– American got the h-bomb • Nuclear proliferation
first
• In this case, it is not true that
• Which leads to the arms – “someone would have done
race and the cold war it”
• Von Neumann’s Princeton
team was … unique
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13. Case study #3
Turing’s “reward”

14. Alan Turing won the war
• Taught Von Neumann how to build computers
• His theories are the basis of all modern computers
• And his reward?
– Persecuted to death
– Homophobic rejection in the 1950s
– Security clearance revoked
– driven to suicide … by apple (sprinkled with arsenic) 13

15. 2009: A public apology
in Parliament
• British Prime Minister Gordon Brown
– issued a public apology for the British
government's "appalling" actions,
– after an online petition seeking the same gained
30,000 signatures and international recognition.
– “The debt of gratitude he is owed makes it all the
more horrifying, therefore, that he was treated so
inhumanely.”
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16. And what is the future?

17. Turing’s challenge to us all:
• Be responsible.
• Leave the shame behind us.
• Build a different future.
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18. CS = building blocks
• In times past, computers were very expensive
– Tools for the military
– For code breaking and designing bombs
• Computers today are cheap
– $30 for Raspberry Pi
– Now, computers are tools
for everybody
– What will do with that?
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19. Alan Turing:
We do more if we do it together
• Alan Turing, 1939:
– “The well-known theorem of Gödel (1931) shows that every system of logic
is in a certain sense incomplete, but at the same time it indicates means
whereby from a system L of logic a more complete system L′ may be
obtained. By repeating the process we get a sequence
L, L1 = L′, L2 = L1, ...
– each more complete than the proceeding. A logic Lω may then be
constructed in which the provable theorems are the totality of theorems
provable with the help of logics L, L1, L2...” .
• Translation
– We are all incomplete
– We all know part of the answer
– We know more if we work together
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20. Teams, working together
• Linus Torvalds
– a guy sitting on his Mum's lounge room floor
– invented a way to build software
– that now powers the internet.
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21. Groups, interacting
• Mark Zuckerberg
– Some guy in his dorm room at Harvard
– created a web site used daily by a billion people.
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22. Welcome to Science 2.0
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23. Computer Science = ideas
Ideas are powerful.
You up for it?