Oral History Transcript — Dr. Wolfgang Priester
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Interview with Dr. Wolfgang Priester
Wolfgang Priester; January 19, 1987
ABSTRACT: In this interview, Wolfgang Priester discusses: University of Göttingen; University of Kiel's Institute for Theoretical Physics; Albrecht Unsöld; University of Bonn; Sputnik observations; Goddard Space Flight Center; Goddard Institute for Space Studies; Isadore Harris; Robert Jastrow.
Doel:This is an interview with Dr. Wolfgang Priester, Director of the Institute for Astrophysics and Extraterrestrial Research of the University of Bonn. We're recording this on January 19th, 1987, in Dr. Priester's office in Bonn. Dr. Priester, I know you were born on the 22nd of April, 1924, but I don't know a great deal about your family, or about your parents. Who were they, and what did they do?
Priester:Is this so important? My father was an architect. My mother was just his housewife. I have a brother who became a teacher of physics and mathematics and sports, and now he's already retired. And right after the war, I started of course to study physics, astronomy and mathematics, and got my PhD in Göttingen in 1953.
Doel:I wonder if, before we get into your university career, we could talk just a little bit more about your life and growing up in Germany. Did you feel that your parents played a strong influence in bringing you towards science?
Priester:Oh, I guess so, yes. Yes, my father was very interested, particularly in philosophy, not too much in physics, but my first book on astronomy, I came to find out, because I was ten years old, and each time I put a mark on with the date when I had finished a chapter, and I still have that old book. I saved it through the war.
Doel:Do you remember the name?
Priester:It was Bruno. It was a popular book on astronomy, which brought me into the interest in astronomy and physics, and of course, this was at the age of ten, and then of course, in high school, what we call gymnasium, I was lucky to have a famous high school which was already more than a thousand years old, and had this old tradition, and basically of course a tradition in Latin and ancient Greek, but of course, in mathematics and physics, so I had a good background, and right after the war, I got into Göttingen University to study astronomy and physics and mathematics.
Doel:What was the program that you had in high school? How much physics and astronomy were you able to take?
Priester:Astronomy, there was no special course in astronomy in high school in those days. It isn't even today. It's just incorporated into physics or geography, and — but mathematics was pretty good, and physics. But since I got my high school diploma in 1942, it was already during the wartime, and of course there was a reduction of everything, and the teachers, some of the teachers had to become soldiers already and so on. And then right after that, after finishing high school, I had to become a soldier too, and spent five years or four years in the war, but very luckily I survived it without major harm, and so, after the war, I started astronomy.
Doel:What particularly led you to Göttingen?
Priester:Oh, in those days it was very simple, because that was the, it was in the first place, a famous university for science, and secondly, it was the university next to my home.
Doel:Were you living at home then during the time you were in Göttingen?
Priester:No, no, of course not. That was 150 kilometers away, and one had to stay in Göttingen. I was lucky to get what we call a student room together with my brother. He studied physics and mathematics and sports to become a high school teacher, which he later did, and so we spent our time of studying in Göttingen together, and that that is —
Doel:Who influenced you the most during the first years at Göttingen? What kinds of courses did you take?
Priester:To get into the university in those days, there was something that we called which was much more severe than it is nowadays, and in particular, I missed, I came out of the war in November, ‘46, out of a prisoner of war camp, an American prisoner of war camp, and so I missed the first semester after '46, and so when I was back home, I took the train to Göttingen and tried to see one of the professors there, just to find out my chances and so on to get into it, and I took my diploma along, of course, and so I met the director of the Göttingen Observatory, a famous chair of Gauss 150 (50?) years ago, and the professor was and he was in solar physics, in those days. He had done lots of work in stellar physics and in particular globular stellar clusters, but this was all before the war, and after the war, he specialized in solar physics, and that's why I later then took my doctoral thesis in solar physics, and made observations of the center limb variation of the sodium D lines in order to find out the temperature variation in the solar atmosphere, and the entire physical state in the solar atmosphere.
Doel:How much of his work did you know already by the time that you first met him?
Priester:Of his personal?
Doel:Of his research.
Priester:His research, hardly anything. I had, in those days, a famous book by Sir James Jeans, what's the name? There's a German translation, “Stars, and Atoms," probably, I don't know what the English title is. I had the German translation of that. And —
Doel:It might be THE MYSTERIOUS UNIVERSE, but we'll —
Priester:— no, no, that's another one. This was not THE MYSTERIOUS UNIVERSE, it was another one. I don't know whether I — I probably have it at home, I kept it somewhere.
Doel:We can check on that later. What other works had you read prior to the time that you came to the university? What influenced you?
Priester:I did do some mathematics, but in astronomy, to get any information in astronomy basically was reading this kind of sort of popular books of a high level, like Sir James Jeans' books, and then, I had a German journal which is, well, it's a journal which is in the level above SKY AND TELESCOPE, because it had lots of equations in it and so on, but it was still considered to be a popular journal, and of course because of that high level, it never managed to get a large number of copies to be sold, so the journal died. I don't know when. Late in the late forties, after the war. It did not survive and doesn't exist anymore.
Doel:Was it a journal that the astronomers would read as well?
Priester:Yes. Yes, certainly.
Doel:Were you certain already when you entered Göttingen that you wanted to work specifically in astronomy, or were you thinking about other choices as well?
Priester:It's a little bit difficult to answer, because, right after the war, you must consider the situation in Germany, and to study a field like astronomy, which is sort of — I think that a very rare field and somewhat, most people think it's a little bit — so I wasn't really certain whether I could manage to stay in research in astronomy, the situation was so uncertain that I was — I said, OK, I study astronomy, physics and mathematics, and these three fields, actually, when I returned every semester then one had to re-enter the university, and the second semester I put, physics, astronomy, mathematics. In the first semester I put mathematics, physics, and astronomy. And so I wrote it every semester. But finally, when it came to start on the doctoral thesis and so on, it was very clear that I wanted to stay in astronomy, and by that time, I had established also a good relation with and other professors, Professor and Professor. He was already in his seventies in that time, and was a young man, and so, the doctoral thesis took me almost three years to finish it, because we didn't have computers then, and everything had to be done with a slide rule. It took a terrible long time to do the reduction of the data and so on. Actually, was very clever, in that I had, for my thesis, I had four students working under me on the data reduction, which you now do with a computer.
Priester:Human computers, four students working for me, and they kept me busy all the time. I hardly could do my research, because I had to supervise their work, doing the reduction for my thesis.
Doel:And these people were hired by…
Priester:They were hired by the Institute, yes, and paid by the Institute. Most lucky. Not everybody was lucky in this respect, but it might be that it was the research project that I was working on was very much interesting to himself, and so. And later on it turned out that this, — got quite a jump in solar physics, because then we realized that the temperature profile in the solar atmosphere is different in different wavelengths, so to speak, and that of course depends on the up and down streaming of the gasses in the solar atmosphere, that makes the temperature profile, which you derive in different wavelengths, becomes a function of wavelength. Sounds very strange if you look at it this way, but it was just due to the upstreaming, downstreaming, and now the whole problem in the solar atmosphere is what people are working on still since now almost 30 years, and it's still a very interesting field, and there are big telescopes to be built, and German solar astronomers just built a very big huge telescope, solar tower in the island of and there was even an inauguration last year. The King of Spain, and Deutches Bunde President, the King of Sweden and the Queen of the Netherlands, and — the Queen of England wasn't there; it was the Duke of Gloucester who replaced her, because the Queen of England is not on good terms with the King of Spain, since about 500 years. It's just because of, but, whatever it was, and then there was the King of Denmark, so there was a whole big inauguration ceremony for this solar tower, the European telescope, two years, it's already two years ago now. It was in '85.
Doel:You jumped ahead just a bit. In 1950 then would have been the time that you began doing your doctoral research.
Doel:Who else were you working with? I would assume primarily with
Priester:Yes, but of course there were assistants in the Institute. It was who later, after in 1960, took a job at the Einstein Tower in Potsdam, in East Germany. And —
Priester:Yes, it's very unusual. He had this offer, and in those days we were still hoping that there would be a United Germany some time, and so he just took his chances, and very unluckily, I would say. He's retired now and I've never seen him again since that time. He did his research with the Einstein Tower, but he never managed to make the jump back into the Western world. Even in 1961, that was before the Berlin Wall was erected, he was in West Germany, actually he attended the IAU meeting in Berkeley, but then he decided, during that time the Berlin Wall was built, and then he decided to go back, despite the fact that he had family in the West.
Doel:Were you in contact with him at that time?
Priester:Oh yes, of course. We were good friends. But I've never seen him really because I never went to East Berlin or Potsdam after the Wall.
Doel:Who else in addition to were you working with? Was there a sense of community in solar physics?
Priester:Quite a few people. For instance, there was who used to be the president of the Max Planck Society, now is director general of the European Space Agency. He worked on his thesis at about the same time, and his wife, Dr. [???], worked — they were not married in those days, they married after they both got their PhDs — and she worked in solar physics in those days, and Liszt took his doctor's, his thesis with at the Max Planck Institute in those days, and I ought to know, the — it's difficult to remember now who else was there. He's now in the States, at Ann Arbor. I've forgotten. It's a long time, thirty years ago.
Doel:Were there other students at Göttingen at that time that you came to know very well, who had an influence on your career?
Priester:Oh, I met my wife there, of course. She studied astronomy too.
Doel:Tell me about that.
Priester:Actually, to get into the astronomy in 1946 in the first semester, when I went to [???] he told me, "I have 19 applications and I will take, because of the numerous classes, a number small against ten, " that was his absolute, it turned out to be four, two boys and two girls. One of the girls is my wife now.
Doel:That's interesting. When were you married?
Priester:We were married in 1950. I was still working on my thesis, and she had given up after the financial situation in '48, when all our money went down the drain, the old money, and we got this new money, and so, her father was a high ranking man at the Karl Zeiss Company in East Germany, in Jena, so he couldn't manage to support her anymore, so she got a job, at the Karl Zeiss factory in Göttingen, in the laboratory as a laboratory assistant, and so she supported the family. Actually it was very nice. I didn't have any money either anymore. My parents had died very early, and so this was the way we managed it.
Doel:How difficult was it to get any kind of fellowship support in those years?
Priester:Oh, there was no fellowship support. The only thing I got, I got a free luncheon every day. That was the support I got. In the free luncheon, actually, most of the time even for lunch time and in the evening. It was the fellowship, you know.
Doel:How much contact did you have with [???]? Did you meet him also after?
Priester:Hard to know all these details, because — oh, it was much more contact than it is now with the students here, much more. There were about, at that time, five or six people working on the diploma of physics or the PhD, and usually once in the semester we were invited to his home, and so, for an evening social, and actually I saw him in the Institute. I saw him every day, because at 8:05 in the morning, he came swooping into the offices and said, "Hello, what kind of new research have you done during the last night?" and you'd better have an answer. Of course, it was also possible to say, "There's nothing new to report on, " but — it was his way of life, at 8:05 he started to go around, so you'd better be there on time. Of course, when I went to the solar tower, then we had to start very early in the morning, because right after sunrise, this is the best time to do solar spectroscopic research, because then the air level is rather quiet and you can, for the center limb observation, you have to do it at 5:30 in the morning in the summer time, and so we went walking up to the mountain every morning, it was half an hour's walk. We didn't have a car and there was no public transportation, so we started at 4:30 or something like that to be there on time. Of course then he couldn't come in at 8:05 and ask us, because we were up on the mountain.
Doel:In 1953, after you'd finished your doctoral research, you became a research assistant at the Institute for Theoretical Physics at University.
Priester:Yes. This was an agreement between [???] who was basically of course an observational solar physicist, and Processor Albrecht who was the famous astrophysicist, theoretical astrophysicist, and talked to Umsalt about my future, and so he suggested that I should, after my Ph.D, take a fellowship of the which he had asked the Kiel for me, but to carry it out, at the Institute for Theoretical Physics at University under Umsalt. It was an excellent idea certainly, and so, my wife and I, we changed to Kiel, and with the 370 marks per month salary, but very luckily there was another Zeiss Company in Kiel and so she was just transferred from the laboratory in Göttingen to the laboratory, the Zeiss Company in Kiel, and so she got a job there and I got a job, so we managed.
Doel:What were you doing? Your job of course was at the —
Priester:She did laboratory work in the factory in Kiel. The factory in Kiel made movie machines and things like that.
Doel:How was the experience at Kiel compared to Göttingen? How was it to work with Umsalt?
Priester:Oh, I guess it was pretty much the same, except the attitude of the two scientists was completely different. I can tell you a little story. [???] was always very careful. He said, "If you get a scientific result, you can never be certain that this is the final answer to everything, so when you put it in writing, you always put it very very carefully that you, let's say, even to leave a little door open in case of uncertainty. "And Umsalt was just the opposite. He said, "Once you have realized that some result is the best thing you can do, and you really believe it's true, then you stick out your neck and say, this is it." So these two poles of , I don't know how to put that in English — so in my career I switched back and forth between the two kinds of attitudes toward science, but I must say that I am more inclined towards Umsalt’s attitude, to stick out the neck, when you realize that this is the best way to do it.
Doel:You mentioned to me that your father was interested in philosophy. Were you also very interested in it?
Priester:Yes, my father read Emanuel Kant and Schopenauer and all these great philosophers, but I myself never really went into it. I had a relation with Emanuel Kant because I was born on the same day exactly 200 years after him. But I was also born in the same day as Robert Oppenheimer when he was 20. Of course by that time we didn't know. We knew about Emanual Kant but we didn't know about Robert Oppenheimer.
Doel:True. Can you tell me a little bit about the research, how you got into doing radio astronomy when you were at Kiel?
Priester:Yes, of course. I started out first to read lots of stuff, and then we had already a technician in Dr. [???] who did the electronic work, and — Dr. Franz [???] — at the Institute, and I was responsible for the program and for the reduction and so on.
Doel:Umsalt had suggested that you do radio astronomy.
Priester:Yes, he suggested it to me by saying, "OK, when you come in from Göttingen, you are new in the Institute," and if I would like to do it, and of course I said I would like to do it, except that I don't know anything about it really, but to read 150 papers, it didn't take me too long because one learns to read them diagonally. Umsalt usually said to read a scientific paper, to report on it, should take you less than 20 minutes. I thought it was a joke, but nowadays really you don't have time more than 20 minutes, except for the very few you really read very very carefully, of course, so one shouldn't make a joke, shouldn't emphasize that joke too much really.
Doel:He may have been ahead of his time. How did you come to the research that you began doing? How quickly did you find the area of research that you wanted to do in radio astronomy, or had Umsalt suggested it?
Priester:No, I realized, from the very beginning, that the only really good thing to do with that five times five meter telescope we had, it was a quadratic device, to do a survey of the entire sky, and I tried to make it an absolute calibration, and just make a survey of the entire sky, and this turned out — because there was already a survey going on in Australia for the Southern Hemisphere made by C.W. [???] and Colin S. Gamm. Gamm died unfortunately in an accident in the Swiss Alps in the later fifties. They had made a survey with a similar telescope of the Southern Hemisphere, and so it was very natural to extend it to the Northern Hemisphere, and in the overlapping area, which is a huge overlapping area of course, to fit both together, and this then became the first whole sky survey in radio astronomy, and the frequency was 200 megahertz, we call them hertz in the States, megacycles per second, megahertz, and so this was l.5 meter wavelengths, and this is one of the three we have on the wall up there. There are three nowadays, all sky surveys. On the left side is my old one, together with von [???], and of course with Colin S. Gamm's part in the Southern Hemisphere, and then in the seventies, who sits next door here in the Max Planck Institute, did it with together at 850 megahertz, and then came the real famous survey in '8l, with the 100 meter telescope, and the Australian 64 meter telescope, at 408 megahertz, which was made by Hazlem and his entire group and of course it's all done on a computer. In my old days, I had to do the data reduction all by hand and even the convolution integral by hand, so to speak, without computer, but I managed to do it. Nowadays you have much more detail, so much detail that you don't see the structure for the details anymore, so it’s —
Doel:I understand. Who, what people did you consider to be most active in radio astronomy at the time? Who did you have the most contact with, both within Kiel and outside? Priester; In Kiel we had a very small group. This was just Dr. [???] and myself really, and the [???], who is now here and manages our 100 meter telescope, and Umsalt of course was interested, but he was occupied writing this very very big book on physics of stellar atmospheres, the second edition, and it took him practically 48 hours per day, I have to put it that way.
Doel:Did he talk to you a lot?
Priester:Of course, we had social contact also, on the research projects, but since he was so much occupied with writing his real famous book, which is a marvelous book still, that we really couldn't rely upon him on all details. He wanted to see the results and that was it and no details please.
Doel:You learned how to condense material very well.
Priester:Of course, during that time we did some other radio astronomy with observation of the solar eclipse which happened to go through Kiel, the shadow area went through Kiel in those days, of course, and we managed to calculate the energy distribution in the solar corona. The resolution was not so good because the moon has the same size in the sky as the sun so the resolution was not good enough really that one can make use of it later on, but in those days it was interesting. But nowadays it's completely outdated, except for the all sky survey, it is good still, if you really want to have the gross structure, then you can still look at it and see what's going on there.
Doel:Right. It was in 1955 that you became part of the University Observatory here.
Doel:How did that come about?
Priester:The research project I had in Kiel was of course a time limited project, and I stayed here for a little bit more than two years, but by that time, the director of the Bonn Observatory, Professor Becker, he died last year at the age of 85, and he had decided to start radio astronomy in Bonn, besides the optical observatory. The optical observatory, the [???] in Bonn, was built, let's see, about , at that time a hundred years ago by [???] who made the famous Bonn [???] of the sky with 320,000 stars, which is still used in the Smithsonian stellar list nowadays, but nowadays it's all on computers, you can take it from the Smithsonian computer. But this was entirely optical observatory, up till about early fifties, when Becker decided that there should be a place in West Germany besides the little effort we could afford at Kiel in radio astronomy to, in those days, the financial situation here in Bonn was much better than it is now, I'd say — and so he decided to build a radio telescope. And so he was looking for a radio astronomer, and since I was one of the two radio astronomers in Germany in those days, in West Germany — in East Germany, at Berlin in East Germany was a large installation under Otto [???] who, in 1961, when the Berlin Wall was created, he lived in West Germany and worked in East Germany, so he couldn't go back to his office anymore, so we got hold of him and got him into Bonn. But this was not so in the fifties. And so we built a 25 meter telescope and started radio astronomy, and the main project in those days was the 21 centimeter line of hydrogen, and so we had lots of work in the hydrogen distribution in, the first place of course, in the galactic spiral arms, and then of course also in extra galactic objects. Of course there you can, with the 25 meter telescope, you usually can only get the entire spectrum, and you can't go into the details. This had to be left then to later development. This was in the fifties. It was, when I came, on the very first days I took office in Bonn, we went out to the Mountain to find the place where to put the telescope, and so Becker and myself, we looked around in that area which was available to us to site and said, "This is the place where to put it, " and that's where it is now. And actually, a little bit and more than a year later, the telescope was ready and working. It started working in '56, '57 really.
Doel:How much trouble was there to obtain the funds?
Priester:For that telescope, it was pretty easy, because it was, in we had a Secretary of State, that's a different term than your Secretary of State — secretary for research in the Ministry, Ministry of Economics, and he was very much interested in promoting science, and actually he was very vital. He , let's see — a nuclear research installation in [???], and he built the Society for Mathematical Research in Bonn and many other places, and also he got funding for the radio astronomy installation, so to get the 3.5 million marks for the 25 meter telescope was really pretty easy, as compared to the situation nowadays. But the more difficult thing was to get enough positions in the new Institute, scientists and so on. Of course, this basically had to be done all by what we call, the money you can get outside the university budget from NSF, so to speak, National Science Foundation, which is the But that means you have to apply every year, every two years, for new money and have time limited jobs and so on. Nowadays we have the time limitation to five years absolutely maximum, because the union's regulations don't allow having a time limit more than five years, because then you have the right to have a permanent job, and since nobody has permanent money or knows it in advance, all these jobs have to be terminated after five years. It is just absolutely disastrous for research.
Doel:An incredible amount of turmoil and turnover.
Priester:It's incredible, but we haven't found any way out of it. We tried very hard since twenty years and haven't succeeded.
Doel:Are there any other positions that you were thinking to go to, outside of Bonn, at that time? Or was that your first choice?
Priester:Let me see. As a matter of fact, when I got the offer from Bonn. I also got an offer from Umsalt in Kiel for a permanent assistantship, because he had got an offer to become director of the Munich Observatory, so he was going back to Munich, and back to Kiel, that is, whether to go to Munich or to stay in Kiel — so he, in Munich, he will get two or three openings for assistantships, but if he would stay in Kiel, he also would get openings there, but by that time, I had gotten this offer from Bonn, and I was in Bonn just for deciding whether I stay here and so on — I got a telegram from Umsalt right after I had decided to go to Bonn. So , but I never regretted it, because the situation in Bonn was, from the financial point of view, was much, much better than in that rather small theoretical institute, so from that point of view, it was a good decision.
Doel:By the time you got your [???] in 1958, you were already working in a number of different fields.
Priester:Oh yes. That's another story. Starting radio astronomy, but the telescope really became effective in the middle of '57, really, and then all of a sudden, on the 4th of October, '57, the Sputnik came out, and in our radio installation… In '57, when the radio installation was ready for starting working, on the 4th of October, '57, the first Sputnik went into the air, and in the radio laboratory was an engineer who had just, at the very first moment he got it from the news, very early on the next morning, had already the beep, beep of the first Sputnik on tape when I came into the office at 8 o'clock in the morning. And he jumped at me and said, "There's a satellite in the air!" And I said," I can't believe it. The American satellite is due in December." "No," he said, "it's the Russian satellite, of course." That was even more exciting, from that point of view. So we looked into it and then got this beep, beep and then realized that, what can we do with it — just to listen to it is nothing for a scientist, so you have to decide, what can you do with it? And so first we just tried to figure out the orbit of the satellite, and in the very early days, we figured out how to install — to measure the Doppler shift, when the satellite comes over and the signal, we get the Doppler shift — so what we had, the information of course was from the newspapers, from the Soviet Tass agency, that the satellite was moving around the earth and so on, in a circular orbit at a height of 900 kilometers above the earth's surface, and that it took it 96.2 minutes for one orbit. So we tried to figure out, to test this, and from the signal we could receive, because it was overcast, there was no chance to see the satellite. The entire October was cloudy in Bonn and was no chance to see it. And, but after two or three days, we realized that there was something fishy with the orbit the Soviets had released, and in particular there was then — actually the satellite started in the night, from Friday and Saturday, I believe, 4th of October, so on that Saturday morning when we started getting the results, and then on Monday, Tuesday, we started to install a Doppler effect measurement device, but on that same Monday...
Doel:Resuming again after a brief interruption.
The story in the first days after the launching of the first Sputnik, with a circular orbit of (height of) 900 kilometers, that Tass made the science community believe. So when we started with the Doppler Effect measurement on Monday, we got the news already from Cambridge, England, that Martin Riles, the famous Nobel Prize, he died unfortunately a couple or two years ago or so, and his group had already achieved Doppler effect measurements of the satellite, and found out that when the satellite passed over Cambridge, England, that the satellite was only 300 kilometers high. So 900 kilometers in the first day, according to Tass, and on Monday, 300, so the satellite came down very very rapidly, and actually we also believed the satellite will come down within this week, and this was the time when we made all Doppler effect measurements, and then also figured out what the orbit of the satellite was, and realized, there was no seeing of a circular orbit. It was an elliptic orbit with a perigee height of 230 kilometers, and the apogee height a little bit above 900 kilometers, but it was only the apogee height which Tass had released, and so this fooled the entire world, and actually the implications were very very severe, by saying, OK, the Russians are able to put a satellite of 84 kilograms into a 900 kilometer orbit, starting at 900 kilometers, with a rocket which brings it up to 900 kilometers — this was outrageous, and all the military were very much anxious to know a little bit more about that, of course. But then we immediately realized that the launching height, the perigee height, was only 220 kilometers, and so, there was nothing really very strange about the whole launching, and so the next day we got in the newspapers, because Moscow also had announced the satellite will not come down in this week, and then we gave the explanation, and so we got a headline in the German newspapers, "Bonn And Moscow Agree the Satellite Will Not Come Down." Which brought us really into satellite research of course. Then after, we immediately realized that there was a braking effect in the orbital motion due to the air drag acting on the satellite, and so one could use this drag in order to derive the density of the upper atmosphere, which , in that area, about 200 kilometers, there was no observational information on it before at all.
The highest rocket which had measured it directly went up to about that height, but there were only one or two rockets really which had measuring devices, and one location on the earth, and now you really could measure the behavior of the upper atmosphere, and so this really started an entirely new group in that institute, and then we found out that the upper atmosphere is breezy. According to solar activity , and it's also that , what has come a little bit later, that the atmosphere is of course being, even the upper atmosphere is being heated by the absorption of the solar [???] extreme ultraviolet radiation, and so this lifts up during daytime the entire atmosphere, and so the lines of constant density, the isobars, go up by , at a high range of 200, 300, 400 kilometers, go up by 50 or more kilometers every day, reaching a maximum height at 2 o'clock in the afternoon or even a little bit later, and then when the sun goes down it settles until at night it settles even more, but rather slowly. This was a very strange effect. And then next sunrise it goes up again, and all these interesting findings we published in that time, most of it we published in German, because our English wasn't good enough. It's still not good enough. But interestingly enough, the Royal Aircraft establishment in England always translated our publications into English, and I've just given them permanent permission to do so, and on the condition that they send us 200 reprints. Until I discovered that this was done by professional translators, and so when we discovered the atmospheric bulge, this blowing up in the afternoon, and we called it in German" which is literally translated" air bearer, "it should be atmospheric bulge, and when I discovered that, and there was another thing — the flux density of radiation in German is [???] , and that was translated as radiation current, so that the whole thing was very silly. From then when I discovered these two very bad mistakes, then I decided we'd rather learn English. Even with broken English, with the correct terms, it's better than perfect English with bad translation of the scientific terms.