As Alastair Rae points out in his introduction, "quantum physics is not rocket science". It may have gained a reputation as the theory that no one really understands, but its practical applications are all around us in everyday life. If it were not for quantum physics, computers would not function, metals would not conduct electricity, and the power stations that heat our homes would not produce energy. Assuming no prior scientific or mathematical knowledge, this clear and concise introduction provides a step-by-step guide to quantum theory, right from the very basic principles to the most cutting-edge developments, such as super-fast computers and unbreakable codes, which could soon become reality. Finally, Rae turns to the philosophical questions posed by quantum physics and asks: if Einstein was wrong and God really does play dice, what are the consequences of this for the way we view ourselves and our relation to the world? Written by one of the most respected authors in the field, this authoritative and readable guide will be suitable for anyone wishing to gain a clearer understanding of one of the key scientific discoveries of our time.