To point out what everyone's overlooking: this was written in 1959, which means the wildest sci-fi nanotechnology he's imagining here... is, basically, achieved

To point out what everyone's overlooking: this was written in 1959, which means the wildest sci-fi nanotechnology he's imagining here... is, basically, achieved by magnetic HDDs since around 2011. "Why cannot we write the entire 24 volumes of the Encyclopaedia Brittanica on the head of a pin?" "Let's see what would be involved. The head of a pin is a sixteenth of an inch across. If you magnify it by 25,000 diameters, the area of the head of the pin is then equal to the area of all the pages of the Encyclopaedia Brittanica. Therefore, all it is necessary to do is to reduce in size all the writing in the Encyclopaedia by 25,000 times. Is that possible? The resolving power of the eye is about 1/120 of an inch – that is roughly the diameter of one of the little dots on the fine half-tone reproductions in the Encyclopaedia. This, when you demagnify it by 25,000 times, is still 80 angstroms in diameter – 32 atoms across, in an ordinary metal. In other words, one of those dots still would contain in its area 1,000 atoms. So, each dot can easily be adjusted in size as required by the photoengraving, and there is no question that there is enough room on the head of a pin to put all of the Encyclopaedia Brittanica." By his assumption, a pinhead is about 0.003 inches^2 (2 mm^2). The current Encylopedia Brittanica has about 300 million English characters [0], which is about 300 MB in a reasonable text encoding (although it should compress [1] to around 60 MB). So, what Feynman is speculating about, translates in digital language to a memory density of 300 MB/(0.003 in^2) or 100 GB/in^2 or 800 Gb/in^2. This is roughly an average magnetic HDD from 2011 [2]. To emphasize the point: Feynman is speculating about a dot "80 angstroms [8 nanometers] in diameter - 32 atoms across, in an ordinary metal". This is actually the size of a magnetic domain on a HDD platter -- wikipedia gives it as 10 nm [3]. Unfortunately, there now exists a far larger English-language encyclopedia which is 9 GB compressed [4] or 75 GB with images [5]. Using Wikipedia as the new benchmark, it is currently not possible to compress it onto the head of a pin. [0] https://en.wikipedia.org/wiki/Wikipedia:Size_comparisons#Comparison_of_encyclopedias https://en.wikipedia.org/wiki/Wikipedia:Size_comparisons#Com... [1] https://en.wikipedia.org/wiki/Entropy_%28information_theory%29#Introduction https://en.wikipedia.org/wiki/Entropy_%28information_theory%... ("1.5 bits per character") [2] http://storageconference.org/2013/Papers/2013.Paper.01.pdf http://storageconference.org/2013/Papers/2013.Paper.01.pdf [3] https://en.wikipedia.org/wiki/Magnetic_storage#Design https://en.wikipedia.org/wiki/Magnetic_storage#Design ("Magnetic grains are typically 10 nm in size...") [4] https://en.wikipedia.org/wiki/Wikipedia:Database_download#English-language_Wikipedia https://en.wikipedia.org/wiki/Wikipedia:Database_download#En... [5] http://xowa.sourceforge.net/image_dbs.html http://xowa.sourceforge.net/image_dbs.html