The Mathemagician talk was very good. Arthur Benjamin showed his ability to compute magic squares, compute the squares of 4 and 5 digit numbers in seconds, and find the missing digits in the product of a known number (his daughter's birth year) with an unknown 3 digit number. He also explained some of his methods. Arthur Benjamin teaches at Havery Mudd College in California. After the talk Mr. Benjamin explained that Harvey Mudd College teaches only science, engineering, and mathematics. It accepts the same kind of top students that go to MIT and Cal Tech. The difference is that Harvey Mudd College hires professors based on their teaching and research skills and not just research skills. Mr. Benjamin said that Harvey Mudd graduates are most likely to continue their education in graduate school of all colleges.
One of Arthur Benjamin's tricks:
To compute the square of a number x, find a close number y that is easy to compute with. The difference between x and y is d, such that y = x+d or y = x-d. The compute the value of:
(x+d)*(x-d) + (d*d)
which is the same as (x*x).
Example:
Compute the square of 23. The nearest "easy" number is 20, and the difference is 3. Compute the value of:
(23-3)*(23+3) + (3 * 3)
or
20*26 + 9
which is:
529.
We ate lunch at Salem Cafe and Restaurant, a Syrian Lebanese restaurant in 13th street. All of use except Sam ordered a salad platter, and Sam ordered a Syrian hamburger. Sam ordered a marzipan cake, and Dan ordered a coconut cake. Rena and I had a fruit salad. The food was very good.
Rena and Dorit went home after lunch, while Dan, Sam, and I went to the Time Since Einstein panel discussion. I fell asleep almost immediately. I can blame the lunch for it. I woke up near the end. Dan fell asleep as well but for a shorter time. Sam said that he enjoyed the panel discussion. I learned a few things from the panel:
- The universe expands by creating space between the galaxies. There is no "center" to the universe.
- The universe expands faster than the speed of light, but it is not a contradiction to the rule that you cannot travel faster than the speed of light.
- You cannot travel from one distant galaxy to another distant galaxy on the other edge of the universe, because the distance between them grows faster than the speed of light.
After the panel we ate dinner at Vegetarian Paradise II in 144 West 4th Street. Dan and I ate there several times, so we knew that everything is vegetarian. Sam was amazed that his "chicken" was made of soy.
We attended the last talk of the day on Nuclear Energy. I learned that Generation IV reactors can burn trans-uranium elements that are created by bombarding U235 with neutrons. The spent fuel of these reactors and conventional reactors can be reprocessed and then reused in Generation IV reactors. The result is using close to 100% of the fissionable material in the fuel, which is a great improvement over the 1% usage rate with conventional reactors. Other added benefits are much lower half-life of the fission waste and eliminating the heat source of the fission waste. The result is a much easier waste disposal of the fission waste.
I asked what is the fraction of the total human production of CO2 (including electricity generation, transportation, industry, heating, and agriculture) that could be eliminated by wide-spread use of nuclear energy. I did not get an answer, but a long speech about the necessity to replace coal generating plants with nuclear plants. I suspect that the answer is pretty low.
We arrived home around 11:30pm.
While reading the complete program of the festival, Dan said that he would have preferred to attend an earlier show of Mathemagician and attend the talk on Avian Einsteins. The talk on Cyborgs on Friday also seemed interesting.
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