Two weeks ago I read Penrose’s new book Cycles of Time. I enjoyed his review of the time’s arrow puzzle, and was intrigued by his proposal that distances fade away in vast infinite futures, allowing them to become tiny flat big bangs again. But not only did Penrose wave his arms pretty wildly on how there could be a metric along which metrics would disappear in approaching the vast-tiny border, he seems to make a very elementary mistake in positing that entropy could have a similar magnitude in our big bang post and our vast distant future, because info is lost in evaporating black holes. The entropy in black hole radiation is more than the holes themselves, which is far more than a tiny flat big bang before.

Well, I haven’t read the book so I can’t be sure this is what you are talking about, but it’s a pretty straightforward task in mathematics to put a metric on the space of metrics.

I think the context may have got muddled. The original question was: "isn’t Penrose’s fame built around mistakes?" I think the graph shows that his rise to fame mostly happened when he wrote "The Emperor’s New Mind" - which is a tapestry of nonsense and mistakes - Q.E.D.

Tim Tyler: It's not surprising that Penrose's name shows up in more text that Google indexes after he publishes his popular books. That metric is a terrible thing with which to judge him as a good scientist or thinker to be listened to, which is what's under discussion.

Ok, good point. I'm looking forward to finding out if any of these theories/laws are falsified one day under special conditions. The 2nd law of thermodynamics seems to be special because it plays a big role in the possible very long-term survival of life in general.

Jess Riedel, we don't disagree about importance. Whatever gave you the idea we did? I said "most widely known if not the most important". Apparently you interpreted that to mean "the most important", dropping the "not".

A black hole, it turns out, is not different. Penroses assertion that black holes destroy entropy is ﬂatly contradicted by the generalized second law of thermodynamics.

I'm not disagree with the idea that if Penrose was contradicting the beliefs of most of the physics community, he should be explicit instead of moseying over it. But for Busso to say his claim is obviously wrong because it "is ﬂatly contradicted by the generalized second law of thermodynamics" is like a 19th century physicist saying nuclear power is impossible because it contradicts the conservation of matter (an idea which had great experimental evidence to support it at the time).

The generalized second law is just a conjecture about black holes (and, ultimately, a quantum theory of gravity) based mostly off of analogies! Seriously, anyone who knows basic general relativity and quantum mechanics can read the original papers of Bekenstein and Sorkin. They are very pretty and suggestive ideas, but hardly conclusive.

Incidentally, Busso is no disinterested appraiser of Penrose. He's a major proponent of the holographic principle, which is based off of the generalized second law and the rest of black hole thermodynamics, and which would be thrown out of Penrose was right (unlikely as that may be). I think it's very disingenuous for Busso to dismiss Penrose, his intellectual opponent, by pretending that a speculative idea like the generalized second law is obviously true.

Of course, I strongly agree with the point about Penrose's latter dabblings in popular books having nothing to do with his fame as a mathematicians and physicist.

I guess "importance" is a matter of taste, but his various general relativity theorems, especially the ones proving the inevitability of singularities, seem vastly more important to me. Granted, I'm a physicists, not a mathematician. But I don't here many mathematicians talk about Penrose tilings, while the GR theorems of Hawking and Penrose are central to learning GR.

Penrose no more built his reputation on Emperor's New Mind than Stephen Hawking built his on A Brief History of Time. Possibly the most widely known, if not the most important, of his contributions is the Penrose tiling.

Sure, I'll play!What if the law of conservation of momentum were wrong? What if the law of conservation of charge were wrong?What if special relativity were wrong?What if the CPT theorem were violated?(After all, why single out the 2nd law of thermodynamics?)

"But not only did Penrose wave his arms pretty wildly on how there could be a metric along which metrics would disappear in approaching the vast-tiny border"

I haven't read the book so I can't be sure this is what you are talking about, but it's a pretty straightforward task in mathematics to put a metric on the space of metrics.

The 2nd law of thermodynamics applies to closed systems, not to open systems. If the universe is an open system, then it does not apply -- at least, in the sense it is usually taken to apply. Also, if information is the opposite of entropy, and information cannot be created or destroyed, then the universe must always remain in balance. If we look at the universe, it has crystalized out into ever-greater, ever-more-complex order. This had nothing to do with black holes (which Stephen Hawking already proved does not destroy information).

## Seek Criticism

Well, I haven’t read the book so I can’t be sure this is what you are talking about, but it’s a pretty straightforward task in mathematics to put a metric on the space of metrics.

Not to be overly critical, but I think you mean, "you’d still DO well to ask for and listen to criticism."

I think the context may have got muddled. The original question was: "isn’t Penrose’s fame built around mistakes?" I think the graph shows that his rise to fame mostly happened when he wrote "The Emperor’s New Mind" - which is a tapestry of nonsense and mistakes - Q.E.D.

Constant: sorry, I can't read.

Tim Tyler: It's not surprising that Penrose's name shows up in more text that Google indexes after he publishes his popular books. That metric is a terrible thing with which to judge him as a good scientist or thinker to be listened to, which is what's under discussion.

Checking Google NGrams, it looks as though the Emperor's New Mind made Penrose: http://ngrams.googlelabs.co...

A pity is was all wishful thinking.

Ok, good point. I'm looking forward to finding out if any of these theories/laws are falsified one day under special conditions. The 2nd law of thermodynamics seems to be special because it plays a big role in the possible very long-term survival of life in general.

Jess Riedel, we don't disagree about importance. Whatever gave you the idea we did? I said "most widely known if not the most important". Apparently you interpreted that to mean "the most important", dropping the "not".

A black hole, it turns out, is not different. Penroses assertion that black holes destroy entropy is ﬂatly contradicted by the generalized second law of thermodynamics.

I'm not disagree with the idea that if Penrose was contradicting the beliefs of most of the physics community, he should be explicit instead of moseying over it. But for Busso to say his claim is obviously wrong because it "is ﬂatly contradicted by the generalized second law of thermodynamics" is like a 19th century physicist saying nuclear power is impossible because it contradicts the conservation of matter (an idea which had great experimental evidence to support it at the time).

The generalized second law is just a conjecture about black holes (and, ultimately, a quantum theory of gravity) based mostly off of analogies! Seriously, anyone who knows basic general relativity and quantum mechanics can read the original papers of Bekenstein and Sorkin. They are very pretty and suggestive ideas, but hardly conclusive.

Incidentally, Busso is no disinterested appraiser of Penrose. He's a major proponent of the holographic principle, which is based off of the generalized second law and the rest of black hole thermodynamics, and which would be thrown out of Penrose was right (unlikely as that may be). I think it's very disingenuous for Busso to dismiss Penrose, his intellectual opponent, by pretending that a speculative idea like the generalized second law is obviously true.

Of course, I strongly agree with the point about Penrose's latter dabblings in popular books having nothing to do with his fame as a mathematicians and physicist.

I guess "importance" is a matter of taste, but his various general relativity theorems, especially the ones proving the inevitability of singularities, seem vastly more important to me. Granted, I'm a physicists, not a mathematician. But I don't here many mathematicians talk about Penrose tilings, while the GR theorems of Hawking and Penrose are central to learning GR.

Penrose no more built his reputation on Emperor's New Mind than Stephen Hawking built his on A Brief History of Time. Possibly the most widely known, if not the most important, of his contributions is the Penrose tiling.

Sure, I'll play!What if the law of conservation of momentum were wrong? What if the law of conservation of charge were wrong?What if special relativity were wrong?What if the CPT theorem were violated?(After all, why single out the 2nd law of thermodynamics?)

What if the 2nd law of thermodynamics is actually wrong? I mean, what if it has... loopholes? >.<

"But not only did Penrose wave his arms pretty wildly on how there could be a metric along which metrics would disappear in approaching the vast-tiny border"

I haven't read the book so I can't be sure this is what you are talking about, but it's a pretty straightforward task in mathematics to put a metric on the space of metrics.

The 2nd law of thermodynamics applies to closed systems, not to open systems. If the universe is an open system, then it does not apply -- at least, in the sense it is usually taken to apply. Also, if information is the opposite of entropy, and information cannot be created or destroyed, then the universe must always remain in balance. If we look at the universe, it has crystalized out into ever-greater, ever-more-complex order. This had nothing to do with black holes (which Stephen Hawking already proved does not destroy information).

Where was his editor and publisher?