Dave :

I would suggest (in defense) the application of the principle (rule) that when the starter of the thread changes topics (from structure and pond weeds in a northern pond to Gilda and singularity), as they have every right to do , then others who reply are not guilty of hijacking. What do you think ?

Theo, Hawking , as extreme sport, would before bed, get out of the chair and force himself to crawl in any way possible up and down the stairs to stay fit and challenge himself to fight on against his disease. The product of a superior mind which he did not have before he became sick. BTW the second pic at the link is crazy!!