### 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.

I don't suppose you have a son called calvin.

Posted by Rob on July 10, 2007 at 12:45 PM BST #

Actually, that information is wrong. Zeroes are actually heavier than ones anyway you slice it.

Look: ZERO is fatter than ONE and the same is true when you compare 0 and 1 (regardless of the font being used).

As odd as it may sound, disks are heavier when empty that's why I'm pushing for a /dev/one so I can "dd if /dev/one of /dev/rdsk/c0t1d0s0" and make my server lighter when disks are not in use

lol, can you even imagine if this were remotely true? thanks for the good laugh

Posted by Oscar on July 10, 2007 at 03:22 PM BST #

This reminds me of a story about airplane design. Of course the weight of an airplane is important. So one of the design requirements the US Air Force imposes is to determine the weight of each component early in the design (so the overall weight of the plane can be estimated so you know early on if you are going to get a plane or a rock, I guess). As software became a part of airplanes, the Air Force asked for the weight of the software. And the programmers responsed that it didn't weigh anything. One day the Air Force guy came back all upset. He was hold a deck of cards and was insisting that this was what the software weighted. To which the programmers responded, "no, you don't understand, we only use the holes."

Posted by Steve Uhlir on July 10, 2007 at 04:57 PM BST #

I'm fairly certain that no increase in weight occurs. If we accept that matter cannot be created or destroyed, but changed from one state to another, then what happens in the hard drive is precisely that and hence no increase in weight occurs. However this has a worrying implication as it means that the information was already on the hard drive and we simply arranged it in a way that the computer could understand. THis implies that hard drives come preloaded with all knowledge and using them is simply a process of organising that information and changing it into a format which can be understood by the computer and then us....

Posted by Mr Thicko on July 12, 2007 at 03:05 AM BST #

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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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