Thursday, 30 December 2010

Fourier Photography?

A lens is a very simple device; essentially a lens "computes" the Fourier Transform of an "object". Indeed you can use lens to do computation (devices such as the 4F correlator). However, instead of using a lens, is it possible to capture a wider field of view directly and use software/hardware (such as GPU) to do the computations, including corrections to have a better (perfect?) lens?

Some related technology:
  • OmniVision's TrueFocus Cameras use "Wavefront Coding" which is a method of optically encoding light (using a special lens) and then using image processing to recover a focused image.
  • IATIA advertise technology that can capture high resolution digital wavefront images and extract phase information from incoherent, polychromatic radiation without requiring special optical components.

Wednesday, 29 December 2010

Ryokan Wabi Sabi

Just found out that there was a Ryokan in Kalamunda.

Student Questions

Scott Kim has some interesting ideas for teachers:

As teachers, we all know that the best way to learn something is to teach it. One teacher told me that he challenges students to invent questions that will appear on the exams. The questions from students are frequently quite hard, and involve students more deeply in their own learning.

This is something I must try -- perhaps for MATH2200 in 2011 ...

I now like the Baroque ...

I hated or ignored Baroque art until I watched Waldemar Januszczak's overview in Baroque! - From St Peter's to St Paul's.

The Lost JFK Tapes

Enjoyed watching The Lost JFK Tapes: The Assassination on ABC1.

Thursday, 9 December 2010

Scott Kim

I first encountered Scott Kim when I read Gödel+Escher+Bach. Later, when I worked for Wolfram Research and lived in Champaign IL, my colleague Bruce Sawhill invited Scott around for dinner and I seem to recall serving up some pretty crappy food including burnt corn on the cob ...

The Moon Hoax



See Darryl Cunningham's 19 page strip about Homeopathy.

One day sir, you may tax it

Faraday's reply to William Gladstone, then British Chancellor of the Exchequer, when asked of the practical value of electricity (1850), as quoted in The Harvest of a Quiet Eye : A Selection of Scientific Quotations (1977), p. 56

The search for randomness

Last night I attended the talk by Percy Diaconis on "The search for randomness" (his publications are listed here). I liked his approach, which focussed on understanding simple ideas in depth.

Diaconis discussed the notions of Newton determinacy, which is physics, versus randomness through examples of coin tossing, fair dice, darts, and shuffling cards. I particularly liked his discussion on the transition to, and onset of, randomness in a deterministic system, following the ideas of Poincaré. Poincaré used the method of arbitrary functions to bound probabilities by the integral of the derivative of the probability density function (PDF). See Keller (1986) on "The probability of heads".

Diaconis developed a (deterministic) coin tossing machine to analyze the dynamical bias in the coin toss. He also used simple ideas, such as variable-speed strobe lights and wrapping of dental floss, to count turns of a coin. The main result is that a coin rotates about 35-40 times/second, and the flight of a coin takes about 1/2 second. An important observation is that a coin spinning on edge is biased.

Regarding roulette, the Eudemonic Pie was mentioned. In Australia and the UK, this book was titled "The Newtonian Casino". I had the pleasure of having lunch with Doyne Farmer, mentioned in the book, when he visited Perth in 1992.

There was no mention of Jaynes, but Bayes was touched upon; the Bayesian point-of-view is that a PDF for a coin toss is simply the best guess for next toss. He stated that De Finetti, Machi, and Smith (1990) 'defined' probability in "Theory of Probability: A Critical Treatment". I should read this book.

Diaconis talked briefly about the quality of and sampling used in random number generators (RNGs) (see How we learned to cheat at online poker) and described how Gilbert, Shannon, and Reed began the mathematical study of card shuffling by introducing a good model for how people shuffle cards. He did not cover RANDU, but talked about the Numerical Recipes authors' bet, and how they went back to physics to generate random numbers (as used on the book's CD-ROM). Nor did he comment on Wolfram's cellular automata RNG which are deterministic and arise from trivial reproducible ICs. See also Hector Zenil's RNG demonstration.

Finally, he was very critical of "big models", something that resonated for me.

Deltoid: The Australian's War on Science

Deltoid, the blog by Tim Lambert, a Computer Scientist at UNSW, has an interesting thread on The Australian's War on Science.

I particularly enjoyed #53 on Chris Mitchell's defence against the charge that The Australian's coverage of climate change is biased; see Climate debate no place for hotheads. Really, who would have thought that? It must have been difficult finding "positive" comments on the science of climate change over the last 10 years of editorials.

One poster commented:
You seem to suggest that Chris Mitchell is a liar. For the sake of balance, you should quote the views of someone who thinks that Chris Mitchell is an idiot. For additional balance, please also include the views of someone who thinks that Chris Mitcthell is a lunatic.
and another:
I'm reminded of an old Private Eye cartoon, where a BBC compere introduces his two guests, saying 'on my right tonight is a government spokesman, and in the interests of balance I'm also joined by a wild-eyed Trot from the lunatic fringe'.
And from former Media Watch host, Richard Ackland:
This thin-skinned reaction is a poor look for a journalist. He doesn't need to use the courts to correct any alleged damage to his reputation. All the freedom of the press stuff that The Oz was spouting looks rather pathetic.
As I no longer have a newspaper to enjoy on the weekend (living in Perth, we really do not have any choice), perhaps I'll just subscribe to the iPad edition of The Guardian.

Wednesday, 1 December 2010

Some sceptics make it a habit to be wrong

I liked Mike Steketee's article Some sceptics make it a habit to be wrong. It is interesting to see the charming but evil Nick Minchin (described as "disturbingly likable" in Howe's recent book; see Howes Alarm) featured; The quote
Smoking is a hideous habit. But I defend the right of smokers in a liberal, free, democratic country to smoke. If people choose to die of something, as a Liberal I think: that's your problem.
is revealing. He forgets that smokers impinge on the rights of others by creating second hand smoke.

I also defend peoples right to choose how to die — as long as they are prepared to bear the cost of their choice. Both my parents died due to lung cancer caused by smoking, which was very sad. However it was fortunate for the rest of society that they did not linger in hospital, taking up a bed in intensive care. To civil libertarians: I am happy for cyclists not to wear helmets as long as I don't have to pay for long-term hospitalisation due to head injuries. Having had more than one crash where my helmet has saved me from a serious head injury, I know what I'm talking about.

I read Steketee's article after attending Naomi Oreskes' public lecture at the University of Western Australia on the Merchants of Doubt. I enjoyed it even more after finding that JoNova hated it (see her post of November 27th, 2010). I was amused to see that she tagged her post "Ad Hominem", which I can only assume means she realised that her own post was such an attack on Oreskes and Steketee. Perhaps Nova was annoyed that she was not mentioned in Steketee's article?

Oreskes' lecture was interesting and mostly enjoyable. That fact that at least 97% of the articles (and scientists) she surveyed all agreed that anthropogenic climate change was real is, I think, not surprising. However, she did not mention the difficulty of getting a contrary view into an academic journal, once a consensus has been reached. This is due to reviewers and editors enforcing the consensus and such "self-selection" can slow or obstruct the progress of science. Nevertheless, I take the position that "truth" in science is reached by a Bayesian process and eventually the weight of evidence wins out (Google "Facts versus Factions"; the first link is to Robert Matthews).

To me, the two most important points Oreskes made about what finally swung the balance against the tobacco industry were (1) scientific activism; and (2) litigation by affected parties. Perhaps what is required in the climate change "debate" is for people most directly and immediately affected by rising sea levels to start legal action. The US government may be dismissive of the effect of their contribution to global warming on Bangladesh or Tuvulu, but if Florida or North Carolina were to sue the Federal government, perhaps the situation could change.