Alan Turing Quotes

Potremmo anche immaginare una macchina calcolatrice che viene fatta lavorare con una memoria basata sui libri. Non sarebbe molto facile, ma immensamente preferibile a un singolo lungo nastro. Per pura ipotesi supponiamo che le difficoltà implicite nell'uso di libri come memoria siano superate, cioè che si riesca a sviluppare gli artifici meccanici necessari per trovare il libro giusto, aprirlo alla pagina giusta e così via, imitando l'azione delle mani e degli occhi umani. Non si può girare una pagina molto velocemente senza strapparla, e se gli spostamenti dovessero essere numerosi e veloci, l'energia richiesta sarebbe molto grande. Se muovessimo un libro ogni millisecondo e ciascuno fosse mosso di dieci metri e pesasse 200 grammi, e se ogni volta l'energia cinetica fosse dispersa senza recupero, dovremmo consumare 10^10 watt, pari a circa la metà del consumo di energia della nazione. Per avere una macchina davvero veloce, allora, dobbiamo tenere la nostra informazione, o almeno una parte di questa, in una forma più accessibile di quella che può essere ottenuta con i libri. Sembra che questo risultato possa essere ottenuto solo al prezzo di sacrificare compattezza d economia, cioè tagliando le pagine dal libro e presentando ciascuna a un meccanismo di lettura separato. Alcuni dei metodi di memorizzazione che sono sviluppati ai giorni nostri non si allontanano molto da questo modello.

May not machines carry out something which ought to be described as thinking but which is very different from what a man does?

"Let us return for a moment to Lady Lovelace’s objection, which stated that the machine can only do what we tell it to do. One could say that a man can "inject" an idea into the machine, and that it will respond to a certain extent and then drop into quiescence, like a piano string struck by a hammer. Another simile would be an atomic pile of less than critical size: an injected idea is to correspond to a neutron entering the pile from without. Each such neutron will cause a certain disturbance which eventually dies away. If, however, the size of the pile is sufficiently increased, the disturbance caused by such an incoming neutron will very likely go on and on increasing until the whole pile is destroyed. Is there a corresponding phenomenon for minds, and is there one for machines? There does seem to be one for the human mind. The majority of them seem to be "sub critical," i.e. to correspond in this analogy to piles of sub-critical size. An idea presented to such a mind will on average give rise to less than one idea in reply. A smallish proportion are supercritical. An idea presented to such a mind may give rise to a whole "theory" consisting of secondary, tertiary and more remote ideas. Animals’ minds seem to be very definitely sub-critical. Adhering to this analogy we ask, "Can a machine be made to be super-critical?

We are not interested in the fact that the brain has the consistency of cold porridge.

Sometimes it is the people no one imagines anything of who do the things that no one can imagine

Infine vorrei avanzare qualche congettura sulle ripercussioni che le macchine calcolatrici elettroniche digitali avranno sulla matematica. Ho già accennato al fatto che l'ACE svolgerà il lavoro di circa diecimila calcolatori umani; c'è da aspettarsi dunque che il calcolo manuale su larga scala scomparirà.

We can only see a short distance ahead, but we can see plenty there that needs to be done.

Sometimes it is the people who no one imagined anything of who do the things that no one can imagine

A digital computer can usually be regarded as consisting of three parts: (i) Store. (ii) Executive unit. (iii) Control. ...The executive unit is the part which carries out the various individual operations involved in a calculation. ...It is the duty of the control to see that...[the table of] instructions are obeyed correctly and in the right order. ...A typical instruction might say—"Add the number stored in position 6809 to that in 4302 and put the result back into the latter storage position." Needless to say it would not occur in the machine expressed in English. It would more likely be coded in a form such as 6809430217. Here 17 says which of various possible operations [add] is to be performed on the two numbers. ...It will be noticed that the instruction takes up 10 digits and so forms one packet of information...

Suppose Mother wants Tommy to call at the cobbler's every morning on his way to school to see if her shoes are done, she can ask him afresh every morning. Alternatively she can stick up a notice once and for all in the hall which he will see when he leaves for school and which tells him to call for the shoes, and also to destroy the notice when he comes back if he has the shoes with him.

Those who can imagine anything, can create the impossible.

[T]he m-configuration may be changed.

If an ɑ-machine prints two kinds of symbols, of which the first kind (called figures) consists entirely of 0 and 1 (the others being called symbols of the second kind), then the machine will be called a computing machine.

For some purposes we might use machines (choice... or c-machines) whose motion is only partially determined by the configuration... When such a machine reaches... ambiguous configurations, it cannot go on until some arbitrary choice has been made by an external operator. This would be the case if we were using machines to deal with axiomatic systems.

It is possible to invent a single machine which can be used to compute any computable sequence. If this machine <math>\mathcal{U}</math> is supplied with a tape on the beginning of which is written the S.D of some computing machine <math>\mathcal{M}</math>, then <math>\mathcal{U}</math> will compute the same sequence as <math>\mathcal{M}</math>.