IT can be a once-in-a-lifetime experience to come across a genius who, despite a severe disability, produces earth-shaking thoughts. This year's Hongkong International Film Festival offers such an opportunity by presenting the life of Stephen Hawking, the world's most famous cosmologist, in the documentary, A Brief History of Time , directed by American filmmaker Errol Morris. The documentary is named after Hawking's book which stunned the world with its theories on the origin of the universe when it appeared in 1988. Adapted for the screen, the book turns into an interesting portrait of the 50-year-old legendary wheelchair-bound British professor, regarded as the modern-day Albert Einstein, through about a dozen interviews with his family, colleagues and friends. One does not need to know anything about the Black Hole to understand the film, which unravels Hawking's efforts to understand the nature of the universe in stages, as well as his amusing human side. When Hawking was small, ''he has 11 ways of coming into the house'', a family member says at the beginning. And when he was about 15, he declared to the family he was staying with: ''I think we should have Scottish dances in the evenings.'' This rather high-spirited side of the future theoretical physicist adds colour to a personality normally known only for his theory on the Black Hole and Quantum Mechanics. Morris factually takes the audience through Hawking's ordeal of facing his personal disaster when, in his early 20s, he was diagnosed with the incurable amyotrophic lateral sclerosis, also known as Lou Gehrig's disease. The muscle-wasting disease gradually reduced him to ''a body of cabbage'' with only the heart, lung and brain functioning. And that is the life that vibrates throughout the film - Hawking's unusual intelligence, which raises him to almost superhuman status. Unable to speak or move, he communicates through an electronic synthesised voice computer and forms sentences by pressing a switch connected to the machine. Besides Hawking's computer voice, his colleagues also help to explain his thinking, such as how it is like falling into a Black Hole. ''You will be squeezed into spaghetti . . . and see some fireworks . . . but you will have no time to analyse them because you will soon fall flatly dead,'' one says. In discussing whether time can go back, graphic images of a tea-cup shattering and then re-assembling into one piece - shards and liquid - serves one's imagination well. One comes away from the movie inspired by Hawking's unbeatable quest for answers to life's most profound questions and his words: ''In our strive for the ultimate triumph of reason, we may probe the mind of God.'' A History of Time will be shown on April 12 and 15 at the City Hall Theatre and Columbia Classics cinema. Tickets are available at URBTIX outlets from April 2.