We need to become more complex if biological systems :are to keep ahead of electronic ones. At the moment computers have art advantage of speed but they show no sign of intelligence. This is not surprising as our present computers are less complex than the brain of an earthworm, a species not known for its intellectual pincers. But sc computers' speed and complexity double every eighteen months and this will probably continue until computers have a similar complexity to the human brain.' But will computers ever show true intelligence, whatever that might be? 'It seems to me that if very m. complicated chemical molecules can operate in humans to make them intelligent, then equally complicated electronic circuits can aki make computers act in an intelligent way. And if they are intelligent, they can presumably en design computers that have even greater intelligence and complexity.' 'On the biological side, the limit of human intelligence has been set by the size of the human brain that will pass through the birth es male' Hawking says. 'Having watched my three child= being born, I know how difficult it is to get the head out. But in the next 100 years 1 expect we will learn how to grow babies outside the human body so this limitation will ro be removed. But ultimately. increases in the size of the human brain through genetic engineering will come up against the problem that the chemical messages responsible for our mental activity are relatively slow-moving - so further increases in the complexity of the brain will be at the expense of speed. We can be quick-wined or very intelligent, but not both.' It's time to ask the big one: will we make contact with aliens in the next millennium? He smiles. His fingers click the pressure pads The answer comes seven minutes later. 'Even if life developed in other stellar systems, the chances of catchigg it at a recognisably human so stage are very small. Any alien life we encounter will be much more primitive or much more advanced than us. And if it's more advanced why hasn't it spread through the galaxy and visited Earth? It could be that there is an advanced race out there which is aware of our existence but is leaving us to stew in our own primitive juices. However, I doubt they would be so amsiderate to a lower life form. Some people believe that the reason we have not been contacted is that when a civilisation reaches our stage of development it becomes unstable and destroys itself. But I'm an optimist. I think we have a good chance of avoiding nuclear war and Armageddon