#### Bah, old news

Lego mindstorms has been doing this for more than a decade. Except the 3D printing bit, you have to do that by hand.

5 publicly visible posts • joined 1 Nov 2007

Saturday 2nd February 2008 03:30 GMT #### A bit more than just 00 01 10 11

I think you've gotten the idea behind quantum computing a bit wrong. Qubits aren't just able to store 00 01 10 11 instead of only 0 or 1. If that were the case then they'd be nothing special.

The reason that Qubits are so interesting is because you can use them to solve problems that are impossible for "normal" computers to achieve in a practical timeframe.

For example, if you want to figure out which two prime numbers multiply together to make 65, a normal computer has to do this by trial and error, for example see if 65 can be divided by 2 (no), then see if it can be divided by 3 (no), divide by 5 (yes) -> ok then the answer is 5 * 13. When the numbers are very big, this takes billions of years even with very powerful computers.

Now the reason a quantum computer could be useful for this problem is because it can effectively try all possible combinations of prime numbers at the same time and immediately find the single correct answer. The Qubits are the reason it can do this.

There are a lot of these trial-and-error problems in practical situations that could be revolutionised by Quantum computing. Cryptography is the most obvious one but there are plenty of others.

Thursday 1st November 2007 12:54 GMT #### Not so dumb after all?

It's a pretty simple idea:

if a 5g bullet moving at 330 m/s undergoes an elastic collision (i.e. no loss of kinetic energy) with an 80kg person initially at rest, then after the collision the person will be travelling at about 0.04 m/s (i.e. 4 cm/s) and the bullet will riccochet off at about 329.96 m/s. The target absorbs a mere 0.064 Joules of energy, the same amount as dropping a marble onto your chest from a height of a metre. As Anonymous coward above said (although he/she got the physics wrong too), simple physics - conservation of momentum and conservation of kinetic energy.

As is clear from the article, this won't work unless you fix the nanotube fibres at the ends, so your armour will have to be very stiff - think a mesh of nanotubes like flyscreen, attached at the points that they cross over, so that any nanotubes being hit by the bullet will pull sideways on the perpendicular nanotubes. The armour would be a shell, not a flexible fabric.

But these are trifling details of implementation, once the theory proves it can be done....