Sir— The death of Stephen Hawking — the man who defied the AlS disease for several decades — has created a vacuum that can never be filled. The remarkable physicist’s work shaped modern cosmology. Although the wheelchair-bound scientist lost the ability to speak a few years after he was diagnosed with AlS, he kept giving lectures by using speech synthesizer. His books that are written on complex and difficult concepts of space and time are often called layman’s guide to cosmology. Hawking will be missed by millions of people around the world. His legacy and work will live on forever.