The weight of an ebook

jamesmith

The weight difference is unlikely to make much difference to holidaymakers' baggage allowances, however, because each new tome is about as heavy as a single molecule of DNA.

Filling a 4GB Kindle to its storage limit would increase its weight by a billionth of a billionth of a gram.

Prof John Kubiatowicz a computer scientist at the University of California, Berkeley, explained in the New York Times last week that storing new data involves holding electrons in a fixed place in the device's memory.

Although the electrons were already present, keeping them still rather than allowing them to float around takes up extra energy – about a billionth of a microjoule per bit of data.

Using Einstein's E=mc² formula, which states that energy and mass are directly related, Prof Kubiatowicz calculated that filling a 4GB Kindle to its storage limit would increase its weight by a billionth of a billionth of a gram, or 0.000000000000000001g.

This is roughly equivalent to the weight of a small virus, while the equivalent number of books – about 3,500 – would weigh approximately two tons.

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