Johnny Ball: A Betrayal of Science

Last night, I took my family to see a Christmas lecture by Johnny Ball, famous as a television presenter that popularized mathematics with shows in the 1970s and 80s such as Think of a Number.

The beginning of his talk was a beautiful introduction to square laws in the work of Galileo, Kepler, and Newton, with some lovely audience-participation demonstrations showing the value of experiment. Unfortunately, this was belied by the second half, a rant in denial of climate change that included statements such as 'The greens don't want modern society to work so they've decided to demonize carbon' and 'Carbon makes up only 1/3000 of the gases in the atmosphere. Can that have such a big effect? I don't think so'. No mention of the IPCC or the scientific consensus that contradicts his view.

The danger in this is that he may leave youngsters feeling that scientific disputes are similar to political disputes, with no understanding of how the scientific method can establish truth independent of popular opinion.

I gather his hosts, the University of Edinburgh and the Royal Society of Edinburgh, had no idea he was going to go off on this tangent. Going by the first half of his talk, he used to be capable of giving a truly wonderful introduction to science for young people. But now he should not be let near them; he has betrayed his trust.

[Update: This incident was reported in the TES
Johnny causes storm in lecture on climate change.]

Speculations on the Future of Science

From Kevin Kelly, former editor of Wired.

"Technology is, in its essence, new ways of thinking. The most powerful type of technology, sometimes called enabling technology, is a thought incarnate which enables new knowledge to find and develop news ways to know. This kind of recursive bootstrapping is how science evolves. As in every type of knowledge, it accrues layers of self-reference to its former state."

Droste

"The Droste effect is a Dutch term for a specific kind of recursive picture, one that in heraldry is termed mise en abyme."

Arithmetic for lists

Here are analogues of sum, product, and exponentiation for lists. Each takes two lists of values, of types a and b, and forms the list of all values of sum, product, and function (exponent) types.

type Sum a b = Either a b
type Prod a b = (a,b)
type Exp a b = [(b,a)] -- represents functions from b to a

(+++) :: [a] -> [b] -> [Sum a b]
xs +++ ys = map Left xs ++ map Right ys

(***) :: [a] -> [b] -> [Prod a b]
xs *** ys = [ (x,y) | x <- xs, y <- ys ]

(^^^) :: [a] -> [b] -> [Exp a b]
xs ^^^ [] = [ [] ]
xs ^^^ (y:ys) = [ (y,x):e | x <- xs, e <- xs^^^ys ]

The first two of these are already built-in to Haskell, in the form of append and list-comprehensions. The third is also quite useful, and I suggest it should be added to the standard List module. For example, if you want to form a truth table for the list of variables in names, your can do so using [True,False]^^^names to form all 2^n mappings of names to truth variables (where n is the length of names).

In case you doubt whether these actually correspond to sum, product, and exponentiation, here are Peano's definitions:

m+0 = m
m+(n+1) = (m+n)+1

m*0 = 0
m*(n+1) = (m*n)+m

m^0 = 1
m^(n+1) = (m^n)*m

And here are the above operations, rewritten to correspond to Peano's definitions:

(+++) :: [a] -> [b] -> [Sum a b]
[] +++ ys = map Right ys
(x:xs) +++ ys = Left x : (xs +++ ys)

(***) :: [a] -> [b] -> [Prod a b]
[] *** ys = []
(x:xs) *** ys = map f (ys +++ (xs *** ys))
  where
  f (Left y) = (x,y)
  f (Right p) = p

(^^^) :: [a] -> [b] -> [Exp a b]
xs ^^^ [] = [ [] ]
xs ^^^ (y:ys) = map g (xs *** (xs ^^^ ys))
  where
  g (x,e) = (y,x):e


Lambdacats

Thanks to Mitchell Wand.

Are our Civil Liberties being unduly eroded?

[From the newsletter of the Royal Society of Edinburgh.]

This Mock Trial, chaired by Dr Magnus Linklater FRSE, was staged at the Society on Monday 19 November, before a capacity audience, who acted as jurors. The protagonists were Baroness (Helena) Kennedy, QC, who led three witnesses, Shami Chakrabarti, Director of Liberty, Henry Porter, Novelist and Journalist and Roy Martin QC, Former Dean, Faculty of Advocates, arguing for the proposition; and Lord (Charlie) Falconer, PC QC, arguing to the contrary, leading Lord Elder, House of Lords, Alistair Bonnington, Solicitor to the BBC in Scotland and Lord McCluskey, former Solicitor General for Scotland. The event was supported by the Faculty of Advocates, Messrs Balfour & Manson and Messrs Simpson & Marwick, solicitors, and the Clark Foundation, to all of whom the Society is immensely grateful. This interesting and entertaining debate can now be viewed on the Society’s web page.

[The audience, in the role of jury, voted before and after the trial. The initial vote was 94 in favor, 33 against, 20 undecided; the final vote was 95 in favor, 45 against, 7 undecided.]

Hubble captures dance of the galaxies

A stunning photo, courtesy of the Guardian.

The Law of Leaky Abstractions

From Joel Spolsky's blog. Obvious, but no less important for that, and I've never seen a name attached to this important phenomenon before.

F# productized

Don Syme's F# will have commercial support from Microsoft, as part of Visual Studio. Well done, Don!

PC PC: Physical or Virtual?

[A post in honour of Blog Action Day.]

As program chair of POPL 2008, I followed tradition and organized a program committee meeting in Edinburgh last September, attended by 22 members. They worked very hard, and went to great lengths to attend (literally---members came from Japan, New Zealand, and India), and the result was a program I'm looking forward to seeing next January.

But after I sent out the invitations, I read George Monbiot's Heat, and began to wonder if I had made the right choice. If the world got serious about stopping climate change, what would be an equitable figure for Britain's carbon emissions? Monbiot reckons we would need to reduce our carbon footprint to 10% of current levels by 2030. Remarkably, he sketches out a plan whereby this can actually be achieved for house heating, energy sources, ground transport, and so on. With one exception: the only way he could find to reduce the carbon footprint of air travel is to travel less. Way less.

I'm not one of those campaigners who believes that the way to save the world is to bike to work. (I do bike to work, I just don't believe it will save the world.) The solution to our problems will be political, not personal. I'm not willing to stop flying abroad for vacation while the Government's official policy is to expand airport capacity.

But the carbon footprint of a program committee is not negligible. (For POPL, we have a 20+ PC, as compared to 200+ attendees.) And conferences are not personal, they are run by collections of people who can express a political point of view.

Without the climate issue, there are strong arguments both in favor of and against physical PC meetings. For me, the climate issue tips it: I think it is time for conferences like POPL to begin to experiment, to see whether virtual pc meetings might be comparable in effectiveness to physical. It's out of my hands now, but the program chair of the next POPL is considering just that.