C S Miller writes: Not much more to add.
The BBC is reporting that "Stephen Hawking is 'very ill' in hospital". He has had a few health scares before, and as a post-graduate he was told he didn't have much longer to live; he's now 67. Link to Original Source
We warn the reader in advance that the proof presented here depends on a
clever but highly unmotivated trick.
-- Howard Anton, "Elementary Linear Algebra"