Monday, May 19, 2008

Where Google got the idea.....

Google's Book Search project is possibly their most ambitious undertaking. From one point of view it is an attempt to reverse engineer a proposal entertained by Alan Turing 60 years ago. He was wondering how to design a computer which would have a very large, efficient and affordable digital memory. As a thought experiment he considered the potential for using books ( a library) as a system of machine memory:

We may say that storage on tape and papyrus scrolls is somewhat inaccessible. It takes a considerable time to find a given entry. Memory in book form is a good deal better, and is certainly highly suitable when it is to be read by the human eye. We could even imagine a computing machine that was made to work with a memory based on books. It would not be very easy but would be immensely preferable to this single long tape. Let us for the sake of argument suppose that the difficulties involved in using books as memory were overcome, that is to say that mechanical devices for finding the right book and opening it at the right page, etc. etc. had been developed, imitating the use of human hands and eyes. The information contained in the books would still be rather inaccessible because of the time involved in mechanical motions. One cannot turn a page over very quickly without tearing it, and if one were to do much book transportation, and to do it fast, the energy involved would be very great. Thus if we could move one book every millisecond and each were moved ten metres and weighed 200 grams, and if the kinetic energy were wasted each time, we would consume 1010 watts, about half the country’s power consumption. If we are to have a really fast machine then we must have our information, or at any rate a part of it, in a more accessible form than can be obtained with books. (a lecture to the London Mathematical Society in Feb 1947, quoted by Hodges: Alan Turing -- the Enigma, p 319)
Turing emphasizes the crucial importance of referential transparency in designing book-based machines ("...right book and opening it at the right page, etc. etc...."). There is no point in having a digital book unless the system can locate each and every constituent element within each and every book efficiently. File-based e-book systems have papyrus-like referential opacity. Google Book Search is certainly not making this mistake. Efficient search, random access, referential precision and interoperability will work together in the digital library.

I do not seriously suggest that Google took the idea for their great project from Turing, but it is remarkable that Turing's modest proposal is being captured in ways that he could not have imagined, but of which he would surely have approved.

2 comments:

Alain Pierrot said...

Wonderful quotation, thanks!

It also raises the question of the granularity of what makes sense for the readers as well as how much time or effort they are willing to spend to satisfy their curiosity…

The answers can vary a lot according to circumstances and types of books or periodicals.

And a very good point made about the fact that access is not costless and must be assessed.

Adam Hodgkin said...

Alain == There are, as you suggest, lots more resonances in Turing's comment:- interesting also that his 'power consumed' calculations are precisely of the kind that will be of concern to Google as they plan computing in the cloud. As they plant their data centres next to big hydro-electric plants.....