Roger Penrose visits Cambridge
11-12 January 1997
(Note: This is a essay based on Roger Penrose's visit to Cambridge while I was doing postdoc in Horace Barlow Laboratory.)
(c) Ken Mogi
kenmogi@csl.sony.co.jp
11 January 1997
On the eve prior to the talk, I went to the station to pick up Roger Penrose with Adar Pelah and Roger Thomas. He came with two large bags. Apparently he just arrived from the States and has been staying at the Royal Society in London for a couple of days. He had this very fragile, elf-like atmosphere. The three of us introduced ourselves, and shook hands.
It had snowed earlier that day, and the air was very cold. We got in the car. Penrose began to explain that he had a bad flu in the states, and one of his eardrums was damaged. So he had some difficulty in listening.
We arrived at the restaurant at 22 Chester Road. It was a nice cozy restaurant with a special private room upstairs. The other guests were already there in the room. John Mollon, who suggested this restaurant to Adar, said proudly that it was almost like dining in one's own house. Horace Barlow, his wife Miranda, and Graeme Mitchison stood up to welcome Penrose. It appeared that they knew each other well.
So the meals began to arrive, and I sat at the opposite side of the table with Adar, and listened to what these old men would discuss. They talked about Scuba diving in Australia, how to publish a successful book, etc. etc. Penrose explained to us about an episode when he appeared in the film "A Brief History of Time". The Hollywood guys came down to Penrose's room in Oxford and said they would make a mock-up of his office in the studio, and made notes, measurements, etc. When Penrose went down to the studio, he found this monster of an office. They had installed a huge leather chair, and one huge desk before it, clean, with no papers scattered over it. And they have stacked the bookshelves with antique books which had nothing to do with Penrose's work. When Penrose sat in the chair, he found that he could not reach the desk. So he tried to pull the chair closer, only to find that it was nailed to the floor! Penrose complained, and there came a bunch of guys who denailed, moved, and renailed the chair. The whole business was incredibly expensive and stupid.
Then they asked to Penrose "when does time flow backwards?", referring to Stephan Hawking's idea that when the universe begins to contract, the time would flow backwards. Penrose answered, "I think that time would not flow backwards under any circumstances". They said "cut!" "No, No, you cannot say that. Please imagine some situation where the time flows backwards." Then Penrose says, "I just cannot imagine any circumstances under which the time begins to flow backwards." "Cut!". "No, No, we cannot take this. PLEASE think of some extreme situation where the time would flow backwards". So finally, Penrose was forced to say something incredibly contrived, something he never intended to say.
When Penrose began to talk, he looked much younger and vivace.
Then Graeme Mitchison said to Penrose that maybe he should show the Greeks the Penrose tiling and went on to ask if he would be able to produce them. Penrose briefly said "Yes".
I asked if he was writing a third book after Emperor's New Mind and Shadows of the Mind. He said yes. And then he said a book titled "The large and the small in the mind" is coming out in February. To be published from Vintage (Random House). Apparently it is a book about physics in which he pours out his opinions about other people's theories. So it should be VERY entertaining. Penrose said Stephen Hawking made some nasty remarks at the end of the book. I asked if he had written about superstrings. Penrose's eyes twinkled. "Yes, that is obviously something I should write, isn't it. But as far as I understand the superstring theory is gone and now they are talking about the m-theory. M supposedly stands for "mysterious", or "mother", or whatever. The great merit of the superstring theory they said was that the theory was unique. But now they have several different superstring theories, the uniqueness is gone. And they start talking about membranes. (Graeme;Does Ed Witten still say that superstrings is the theory of the 21st century?) Yes, I think it is still in the air. (Penrose looks at the watch). But the 21st century is just around the corner. I think they should hurry!"
Well, the dinner was over and the evening ended prematurely.
I took Penrose to St. John's college in Adar's car. The drive was a few minutes. Penrose sits in the front seat, I in the back. I begin to pour out.
"I think you should be able to derive the whole quantum mechanics from your twistor formalism. Don't you agree?"
"Well, there are these long-term dreams that you cannot work out right away. I still think quantum mechanics is incomplete"
"I noticed that you draw all the illustrations in your book. In Shadows of the mind, there is one particularly elaborate drawing about the evolutional merit of consciousness. A man is drawing some geometrical figures on the ground, while a tiger is about to jump onto him"
"Yes. There is a joke in that drawing, which nobody has noticed. It is the theorem that the guy is trying to prove."
(By this time, we are in St. John's college, and we are walking toward Penrose's room)
"Have you come up with a three-dimensional version of your tiling?"
"Yes, not me, but somebody has thought of it."
"How many pieces do you need?"
"4. In fact, there is a non-periodic tiling with just one piece. But this is not very interesting. It just spirals out from a point."
"Oh, like the one you have in Emperor's New mind. But that is two dimensional, of course."
"It is not difficult to explain this to you, Suppose there is a .....(I cannot catch the word). Then you add a roof to it. ....The angle is a irrational number..... but this is cheating, really."
"There is no (quasi) translational invariance in that case."
"No."
"You give this example of non-computational dynamical evolution which is defined using the halting of Turing machines. Suppose you have a particular series of evolution (in discrete time). Surely there is at least one algorithm that produces the same result?"
"Yes, you always have to think of a class of problems, you see. If you consider only one particular example, you can always do it computationally."
(I want to ask him if that class should have aleph 1, but we are approaching his room now.)
"That particular example of non-computational process is a non-implementable one, isn't it? Do you think you can ever come up with an implementable version of non-computational process?"
Penrose says something like "****" , but we are in front of his room.
So I and Adar say good night to Penrose. He looked very very tired by then. Maybe the trip to the States and the flu taxed him. So that was "day one" of my first encounter with Penrose. The clock was 11:30 p.m. On the way back to home Adar said he liked Penrose.
12 January 1997
On Friday, I went to pick up Penrose in St. John's college. We went up the spiraling stairs of the tower, and knocked the door of the senior guest room 1. There was no answer, and Adar had to knock on the door again and again.
A few minutes later, we heard some noise. Penrose opened the door and we walked in.
I saw several transparencies scattered over the table by the window. Some colour pens were laid down near the chair. Penrose began to pack his things, and told us about a time when he stayed in the same room. While he was working at the desk, he saw a helicopter land on the greens in front of the building. Several police cars rushed to the scene. It was Princess Anne visiting Trinity college.
Penrose asked me if I have come across a hard copy of the Psyche-D paper. He said that David Chalmers was the guy who originally induced him to write for Psyche-D, on two conditions. Namely, that the number of commentators should be less than 10, and that a physical copy should be eventually produced. Penrose asked David Chalmers if the copy was available, and he said yes, but so far he has failed to send any!
Penrose then said the last time he was there, a swarm of ladybirds invaded the room overnight. Adar said there was something about the colour of the ladybirds that makes you avoid harming it. I said that ladybirds are supposed to taste nasty any way, and added "not that I tried it". Penrose joked that he supposed that ladybirds were not considered as delicacies in Japan. I said no.
As we walked toward the bridge of sighs (St. Johns built the bridge imitating the famous one in Venice), I began the questions.
"If you take any particular result of non-computational process, you can always simulate it by a computational process. You said yesterday that you have to consider a class of problems to make a distinction between computational and non-computational processes. Is it the case that the class must be aleph 1?"
"No, that is not necessary. You see, I understand the argument about computability is always within the bounds of countable infinity. When you consider only the countable infinity, within that there is a special class of recursive functions....that is computable..."
That was as far as we got when we came to the porter, and Penrose returned the key. We got on the car.
Adar began to ask if he could use Penrose tiling for his home.
We parked the car in front of the Kenneth Craik building, and we walked up to Horace Barlow laboratory. I asked Penrose if he knew Horace Barlow before last night, and he answered that he has actually known Horace for a long time.
Adar took Penrose into his office, to settle the travel fare compensation, etc. Penrose asked for a copy of Shadows of the Mind, and began to prepare for the talk. I went to my mac and checked the mails. Some minutes later, I went up to him and gave him a non-periodic tiling handkerchief that I got when I was in Riken from the quasi-crystal laboratory. Penrose was delighted. The tiling had hexagonal symmetry, with two elementary pieces, it was not Penrose tiling, which has pentagonal symmetry. He said it was by a man named Amal?? and was fascinated by the handkerchief. He went on to say that some people confuse tiling by other people with Penrose tiling. In fact, "Penrose tiling" was sometimes used as a generic name for the whole class of non-periodic tiling. He asked me if I could really spare it, and he was genuinely glad to have the handkerchief. He said Amal? was an unlucky man, already deceased, who never had any real job. Then he bubbled on about non-periodic tiling with 12-fold symmetry, etc. It was a topic he loved.
Adar and Penrose went to the tea room. I joined them with my own coffee cup with the photos of Hara Setsuko on it. When I walked in, I found Graeme Mitchison already sitting in front of Penrose! Horace Barlow was there. A few minutes later, Andrew Huxley (who formulated the so-called Hodgkin-Huxley equation which describes the action potential in neurons and was awarded Nobel Prize for Physiology or Medicine) walked in, and Horace stood up and introduced Penrose to Huxley. Huxley is some 10 years senior to Penrose. Later, Adar told me that Huxley did not know Penrose, and said "you are the son of ??? Penrose, aren't you?" Huxley only recognized him as the son of his father. There was some humour in it, when you consider two men of age 66 and 76 talking to each other like that!
Graeme Mitchison was still talking about how to demonstrate your intellectual superiority when you travel back to ancient Greek! I talked with Horace about his forthcoming trip to Australia.
The lecture began at 1:00. Most of the stuff I knew very well from reading Emperor and Shadows twice each, so I just paid attention to Roger Penrose himself. He used two projectors. He began the lecture with the transparency of three spheres figure showing the relation between the physical, mental, and platonic worlds. I thought to myself maybe that was the figure which would represent 100 years from now the whole philosophy of Roger Penrose. Then he went on to argue about the non-computational nature of our intelligence. "Intelligence" needs "Understanding" needs "Awareness". All the transparencies were hand-written with colour pens. I found out that actually he was very fond of colors. Earlier, Penrose gave a direction to Adar Pelah in which color he should paint the three spheres representing the three worlds in the poster announcing his talk. For some unknown reason, Penrose thinks that the colours of the physical, mental, and platonic worlds are blue, red, yellow, respectively. I actually asked Penrose why he chose these particular colors as we walked up to the Barlow laboratory. He had no idea!
After the lecture, there were three mediocre questions. Adar had to cut it short, as Penrose had already talked for 70 minutes, whereas he was supposed to stop after one hour.
We went to the reception room. There I found Srimant and Adam. Adam is a earnest part II student who is doing some project with Srimant. Adam asked me what he should read to study computational neuroscience, and I suggested the book by Sejnowski. Penrose was surrounded by several eager youths.
Horace told me that he liked the lecture, and said it is possible that Penrose was right. He said Penrose was an awfully clever and charming fellow. But, for himself, "he is happy to live with the conventional classical physics".
Penrose wanted to catch the 3:00 p.m. bus to Oxford, so I and Adar whisked him out of the reception. As we went down the stairs, Graeme Mitchison catches Penrose. "Roger, you should come to my dinner party. I have these wonderful dinner parties".
As we walked to the car, I asked Penrose the most important question.
"I think you would rather think that the quantum reduction process is deterministic."
"Yes, that is right. Although there is some complication about the influence of the environment, which makes the dynamics random."
"If you have an isolated system, and the system reduces itself on its own, that reduction would be deterministic, wouldn't it?"
"Yes. I cannot say I am certain. But I would rather prefer it to be that way."
10 minutes later we saw Penrose off at the bus station. As we were standing in the queue, Penrose suddenly turned back to me and said if I had any question to ask him, I was welcome. I thanked him and just then the driver was ready to sell him a ticket. I noticed that the weather was getting mild.