Tuesday Jul 10, 2007

Laptop Mass

Here is a question that comes up again and again and I was asked it yesterday:

As I add more data to my laptop will it get heavier?

You would expect the answer to be yes, but it is not that simple. Since most data is made up of ones and zeros the ones, which weigh more are balanced out by the zeros so in general you don't notice.

The exception to this is when you store a lot of dark photographs. Since these contain more ones these photographs increase the weight of the disk. This is a particular problem for astronomers since most of the pictures they take through their telescopes are taken at night their disks tend to be heavier. They refer to this as “dark matter” and is one of the explanations for the apparent mass of the Universe.

While many think that digital photographs will not fade, this is not true if they are stored on rotating disks. The centrifugal force tends to throw the ones to the outer parts of the disk so photographs in the centre of the disk will fade while those at the edges get darker.

Measuring the effect is hard. With some really sensitive scales you may be able to notice this on your laptop, but remember to remove the battery otherwise the effect is overwhelmed by the difference in weight depending on whether the battery is charged or uncharged.

So that has cleared that one up.

For more information see here.

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This is the old blog of Chris Gerhard. It has mostly moved to http://chrisgerhard.wordpress.com

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