All of my life, I have been fascinated by the big questions that face us, and have tried to find scientific answers to them. If, like me, you have looked at the stars, and tried to make sense of what you see, you too have started to wonder what makes the universe exist.

Now, radical forward thinking is offering hope for the future: Replacement body parts to order. A team of scientists in California believe that if you can design them on a computer, you should be able to print them out.

Of course it is possible that UFO's really do contain aliens as many people believe, and the government is hushing it up

There is a very real danger that we will kill everything on this planet now that we have the technological power to do so.

My first popular book, 'A Brief History of Time,' aroused a great deal of interest, but many found it difficult to understand.

We should seek the greatest value of our action.

I think those who have a terminal illness and are in great pain should have the right to choose to end their own life, and those that help them should be free from prosecution.