Fully Loaded Kindle’s Weigh More? Huh?

Apparently so. But we are talking only a very, very small difference. Less than the weight of a virus!

Kindle makes for heavy reading

“One of the original selling points of Amazon’s Kindle was that the device weighed no more than the average paperback. In the brave new world of the e-reader, bibliophiles could load their gadgets with the complete works of Proust, Tolstoy and Dickens without fear of spraining their wrists on their way to work.

So imagine the consternation among gadget fans when it emerged this week that the Kindle actually weighs more when it is fully loaded with books.

John Kubiatowicz, a computer scientist at the University of California, Berkeley, tackled this vital question for the New York Times. He explained that e-readers store data by trapping electrons, and while the number of electrons in the gadget’s memory does not change, it takes more energy to hold them in place than to leave them roaming free. How much more energy? Around a billionth of a microjoule for each bit of data stored.

Working from Einstein’s famous equation, which states that energy and mass are equivalent, Kubiatowicz worked out how much the weight of a Kindle might change as the books built up. He compared an empty four-gigabyte Kindle with a full one, in which half the electrons were trapped, requiring an extra 17 microjoules of energy.

Popped into Einstein’s formula, this gives an answer of around one attogram, meaning the weight of a full Kindle was a billionth of a billionth of a gram more than a factory-fresh one. Which isn’t so bad, considering that 10,000 books – a fraction a Kindle can hold – might weigh five tonnes. An attogram, very roughly, is one tenth the weight of a small virus.”