Richard Feynman
Richard Feynman proposes two techniques to write on a minuscule space. First, we need to understand that nanotechnology does not magnify a sample to its simplest form, but precisely the opposite. It comprises taking an object in its original form and then compressing it as a whole to its smallest form imaginable. To do this, we have to employ the use of an electron microscope but with a few modifications. Richard proposes the reversing of the lenses of the microscope so that we can magnify as well as demagnify. After which we can send a source of ions in reverse through the lenses of the microscope and focus these ions to a very tiny spot. We can use this very tiny spot of ions to write in the same way as in a TV cathode ray oscilloscope, by scanning across in lines. Feynman suggests an adjustment of the amount of ions to be deposited on a surface as we write in lines. However, this process can be very slow because of – as Feynman puts it – space charge limitations.
Later on, other rapid methods would hopefully be developed, and as a start, Feynman proposes some photo process as an example. In this method, we would strike an arc behind a screen with holes in the shape of letters, to draw metallic ions through the holes. Besides that, there is a more straightforward way, but Feynman is skeptical about its practicality. It is as follows: We run a light backward through an optical microscope and then focus it onto a very tiny photoelectric screen. Electrons will come off the photoelectric screen where the light shines. These electrons are demagnified down in size by lenses on the electron microscope to strike directly on a metal surface. Feynman wonders whether such a beam of electrons will etch away the metal surface if focussed long enough. If the beam of electrons is ineffective on metal, we can find a suitable material surface to coat the original pinhead.
Apart from writing information and pictures in their original form, we could represent the information content in the form of a code – for example, of dots or dashes or something similar – to represent various letters. In this case, each letter will represent “bits” of information say six or seven “bits.” That is, we will represent each letter with six or seven dots or dashes. This method makes it possible to write not only on the head of a pin as earlier described but also on the interior of the material. Feynman assumes that there are 24 million books in the world, and estimates the number of letters herein. Then, he calculates the bits of information in there. By allowing 100 atoms for each bit, it becomes clear that all the information in these books can be written in “bits” to fit a cube of material whose width is one two-hundredth of an inch.
Writing using code or “bits,” it is possible to compress all the information present in all books of the world and fit it on a space that is the size of the barest piece of dust that can we can see with the naked human eye. The speck of dust is infinitesimal. It is akin to DNA molecules that carry all the information in a cell of a human body.