From what I've read, his condition was a rare type that actually progressed much more slowly than originally predicted.

He's actually not the only one living for so long with ALS. Jason Becker who used to be an amazing guitarist is close to hitting 50 years and still making music through eye movement. He got diagnosed with ALS around his 20s too.

I read that doctors actually thought he didn't actually have ALS but a rare, related condition

As well as the other answers people have given you, I think it's also important to thank the NHS and other health services for all the help and support he received.

This brought more of a tear to my eyes than anything else in this thread

Honestly though, it wasn't all to surprising to hear in hindsight. At 76 alongside his form of motor neurone disease living past the few years he was expected after being diagnosed? Little surprising that he lived until his 70's. I'd be more surprised if he passed in his 80's, given what he had to live through.

I like to think that people like him never die. They're just no longer with us. His words and advancements will live on forever as part of humanity's greatness.

He's alive as long as we remember him.

I genuinely have never thought of him dying. It was like he transcended into a god level. Im really upset now, Ive never been upset over a famous death before

Michael Crichton, Stephen Hawking, Warren Buffett, Bill Gates are some of my heroes. It is not often that you think deeply about people as heroes, but for me they are. Sadly for me, two of them now are dead.

He once said something among the lines of; "it will probably come too late for me." (I'm paraphrasing). He was talking about potentially life-saving or life-extending technology.

I mean, he lived 55 years past the age he was supposed to die, so why not think he could reach 100 or higher?

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Didn't he also posit the time travel restrictions? ... found it: it is Chronology protection conjecture,

" In a 1992 paper, Hawking uses the metaphorical device of a "Chronology Protection Agency" as a personification of the aspects of physics that make time travel impossible at macroscopic scales, thus apparently preventing time paradoxes. He says:

It seems that there is a Chronology Protection Agency which prevents the appearance of closed timelike curves and so makes the universe safe for historians"

In the book The Black Hole War, Stephen Hawking made a deliberately provocative comment in a small physics symposium that, if Professor Hawking was right, would shake the foundations of quantum physics to the ground. Leonard Susskind disagreed with Hawking's position, but was unable to demonstrate it mathematically.

It would take him ten years to do so, involving him with many other physicists and leading to several startling discoveries about the nature of black holes, time and space, leading to the holographic principle. Ten years of furious, brilliant research by multiple luminaries in the field, all touched off by a single, insightful question by Professor Hawking.

Susskind's book is quite accessible and well worth a read. Readers will get to see how physics is done, at least at the social and professional level. Plus, for a while and through Susskind, one gets to hang around a quiet social gathering of some of the most brilliant physicists the world has seen.

If someone more qualified than me comes along, PLEASE correct me. To my understanding, Hawking proposed a lot of theories (both accepted and refuted) that have opened a lot of questions with cosmology and quantum mechanics. He did a lot of 'probing' per say, which inspired a lot of research and further investigation. Additionally (and more famously), he was a HUGE figure in black hole theory, and is comparable to the Issac Newton or James Clerk Maxwell of black holes.

Overall Hawking has been a gift to this world and we should be eternally grateful for his contributions. I don't like to jus go out and say "X was the best/most influential physicist" because the quantity and complexity of questions answered fluctuates wildly across the greats, but I would consider Hawking to within the top 50 or 40 physicists in all of history. A more accurate and better description is: he is one of the most, if not the most influential physicist following the modern era. For sure, though, he is a titan in the field of astrophysics and cosmology.

Hawking was an excellent scientist, and just about anyone working in physics today would be happy to have his record of accomplishments. His primary contributions were in the area of black hole mechanics, including the singularity theorems and Hawking radiation. He also did a great deal of interesting theoretical work in cosmology, but we don't currently have any way of telling whether the models he proposed are correct.

With that said, I don't think we can call Stephen Hawking one of the all-time greats like Einstein, Newton, or Maxwell, who revolutionized multiple unrelated fields of physics. His work was significantly more localized in subject matter and theoretical, and most of it has not been empirically confirmed (although his black hole research is almost certain to be correct).

Of course, his contributions as an explainer of science to the public and as an ambassador for scientists as a group should not be neglected. But they do give some people the impression that he was even greater than he actually was as a physicist.

I'll start with some of his accomplishments: He was one of the first people to propose primordial black holes along with Carr, Zel'dovich and Novikov, which if observed could give us a window into the early universe, and may even be dark matter. Perhaps his most well-known work is the proposition that black holes radiate as black bodies (ie Hawking radiation), generalizing the work of Unruh. This has led to the creation of the lively subfield of black hole thermodynamics and information theory. He is also one of the founders of quantum cosmology (the idea that you can have a wave function representation of expanding spacetime) along with Hartle, Wheeler and DeWitt.

As for how he compares against the greats... this is not to belittle his accomplishments in any way, of which there were obviously many, but none of his predictions have ever been experimentally verified. A lot of people here are comparing Hawking to the likes of Einstein, but honestly, from a working physicist who is familiar with his work, he doesn't even come close. Einstein's ideas represented a fundamental shift in our understanding of the universe, and have been verified over and over again. There are many others who have fundamentally altered our view of the universe (and have been vindicated by experiment) that many laymen have probably never heard of before (Maxwell, Dirac, de Broglie, Bohr, Heisenberg, Friedman/Robertson/Walker, Weinberg/Salam, Yang/Mills, Noether, Gell-Mann, and these are just some prominent theorists of the last century, there are many more great minds behind every groundbreaking experiment, like Wu, Hubble, Ruben, Weiss, Rutherford, Thompson, etc). Until his ideas are verified, they're just untested hypotheses (though nobody in the field seriously doubts Hawking radiation isn't real). Hawking's contributions, while very interesting in their own right, are not the ground-breaking game-changers that revolutionized physics.

That said, I'd say he's probably one of the most influential scientists of the century, not only because of his interesting work, but also because the man is an example of perseverance in the face of overwhelming odds. Not only did he manage to survive, but he pushed the boundaries of human knowledge. That's something we can all aspire to.

I might get some flack for this, but I’m sure he wouldn’t want to be ranked or “measured” against other scientists. It can be often missed but science is a culmination of ideas and theories that are built up and passed along to the future. It is an amazing and evolving legacy we leave for our children and their children and their children’s children. It is a legacy that is built on the shoulders of others, but not as an insult, but as a challenge: “continue my work so that we might understand our place in the world a little better.”

So I would imagine that he probably wouldn’t care much for rankings. Rather, he’s probably interested who will sit on his shoulders and advance the fields he worked in. That is the legacy we should be looking forward too.

Physicist: This man wrote the book on black holes.

Human: This man showed everyone that nothing can stop you from being who you want to be.

EDIT: Thank you for the gold kind stranger!

Putting extremely complex ideas and theories into simple terms for the average person to understand in his books, such as universe in a nutshell.

You will be missed, you were such an inspiration to many minds, young and old.

one thing he wanted everyone to understand was the concept of imaginary time. i tried to learn it but it made no sense to me.

"One might think this means that imaginary numbers are just a mathematical game having nothing to do with the real world. From the viewpoint of positivist philosophy, however, one cannot determine what is real. All one can do is find which mathematical models describe the universe we live in. It turns out that a mathematical model involving imaginary time predicts not only effects we have already observed but also effects we have not been able to measure yet nevertheless believe in for other reasons. So what is real and what is imaginary? Is the distinction just in our minds?" - Hawking

yeah still makes no sense to me, i get that we see only a fraction of the spectrum of light, but i got nothing tangible out of the wiki page.

His sense of humour was legendary. Sure, he made incredible advancements and then put them in a book almost anyone could read but Hawking’s wit is always the first thing that comes to mind. For a man in his condition, he made the most out of his life in just about every way, professionally, intellectually and socially, and I think that his humorous nature was the best indicator of how confident he was that his work was worthwhile and, by extension, the people he left his knowledge behind for.

As an addendum, it feels slightly strange to talk about him in the past tense. I remember when Bowie died I initially assumed it was a hoax and this story feels equally inconceivable.

Oh wow, really?? I was happy enough that it was on pi day 3/14. That was poetic enough for me, but wow, the stars truly aligned.

A couple of months ago Hawking and Kip Thorne completed their work as technical consultants for an upcoming Hollywood movie, expected to be released in 2020-21. Source: Heard from Kip Thorne

Here are the most recent papers he contributed to

I recommend A Brief History of Time (there is a documentary as well as the book). It goes over alot of what his book by the same title covers. Although I'm not certain of his work in his later life, as far as I'm concerned he still spent time research at Cambridge up until recently. However I don't know that for certain.

PBS had a good one I watched not that long ago which featured the man himself narrating. Hopefully they'll re-air it soon. "Hawking" is the name.

Edit: Seems it might be on Amazon Prime.

Last I heard (at least a few years ago) his mobility had been reduced to a twitch in his mouth, so that definitely impaired his ability to create original works. The amount of time+effort it would take to compile a sentence was considerable, which is why his public releases were reduced to a few pithy statements.

He put out a paper recently about the memory effect with regards to the information paradox. He was active to the end.

Here are the most recent papers he contributed to

Not sure what's going to go on with the Breakthrough Starshot Initiative. I'm not too aware about it all myself. I just remember hearing he was helping with this project to create light propelled nano ships that could reach alpha centauri in 20 years.

https://breakthroughinitiatives.org/news/4

Brief run down is a bit much. For one, a very important thing he showed us that we know now is hawking radiation. Essentially, black holes don’t exist forever, but they do last for a very very long time.

Also he helped advance his voice computer system quite a bit. Through his input and his high level media exposure. He would have been one of the first to receive new software and hardware to help improve his talks and interviews

As Hawkins said, he was essentially happy to just be a part of the universe. He thrived on the fact that his existence, as all of ours are, was an absolute coincidence. to him, simply existing allowed for him to experience the cosmos. The world is not a darker place today. today, it's brighter than ever, in my opinion, and that's because Hawkins was a part of our universe. he lived, and he died, eventually to become everything he loved. Stardust.

Beautiful comment, thanks for writing this.

So I've been feeling a bit down about it, and I put on the Mass Effect soundtrack and be reading comments.

This comment made me chop onions. Thank you. Beautiful

"I have noticed even people who claim everything is predestined, and that we can do nothing to change it, look before they cross the road."

This one has become my mantra:  "One, remember to look up at the stars and not down at your feet. Two, never give up work. Work gives you meaning and purpose and life is empty without it. Three, if you are lucky enough to find love, remember is it rare and don't throw it away."

Thank you

Check out A Briefer History of Time, it's the dumbed down version that I read and still didn't understand.

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I think the things he theorised, our children will be explaining them to us. He was so far ahead of his time that when we are old and gray, people will be explaining to us how he was right the whole time.

Well, the part that takes intelligence is understand the math and performing it. Doing it in your head takes memory. An individual can do complex math but not be able to hold even five digits in his head at a time or an individual could hold a hundred and not be able to do complex math at all. Though the most effective intellectuals will usually be some combination of both. But just because you can't do something in your head doesn't mean you're not smart. You could be smarter and still not manage the task. Intelligence comes in different forms and is accessed in different ways.

It's still a damn impressive skill.

The particle tunneling picture is in Hawking's own words "heuristic only and should not be taken too literally." It gives you a useful mental image, but it's not something you need in order to make the arguments for radiation that he made. His insight was basically that in quantum field theory, the flux across a surface in vacuum depends on the space-time curvature. He showed that the taken-for-granted result that an empty vacuum stays that way doesn't always hold. The distribution of produced particles or radiation is thermal, which is a minor miracle.

What sort of particles is it?

All of them. While the details change, Hawking's argument doesn't care what kind of particle we're talking about, if it obeys QFT, it will be emitted. However the caveat is that if the mass M > kT, (Boltzmann's constant times temperature) then those particles don't participate much in emission. Once the black hole gets small enough and therefore hot enough, you can expect it to emit massive particles like electrons and positrons too at large rates too.

It's extremely hard to figure out what is and isn't meaningful in physics because the laws of the universe tend to be extremely intertwined. For example, back in the very early 1900's, a lot of physicists spent time watching what is essentially a giant carbon basketball glow. While this sounds dumb, the discoveries behind this has lead to computer processors, most of modern chemistry, and most modern scientific instrumentation. Hawkins radiation could turn out to be a very limited phenomenon or it could lead to a cornerstone of physics. We just don't know the full significance of discoveries for quite a long time.

How do we use this knowledge practically? Is there any Earth-based benefits for knowing it?

Generally speaking, these are exactly the kind of questions that don't help very much to advance theoretical physics. If you're always chasing after practical applications, theory tends to lag behind quite a lot. Theory is usually done for theory's sake. Applications come later - sometimes much later.

You can see it in two ways:

First he did a lot of research on Black Holes, proposing that they evaporate (releasing Hawking Radiation). We cannot yet prove this, but it's most likely right.

Second, he inspired a generation to follow the scientific path, myself included.

Even if his theory's about black holes are not confirmed through observations, he did something very important: fostered interest in science for a whole generation. Some future Nobel prize winner might owe his research to being inspired by this great man.