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Interview of Sidney Van den Bergh by Spencer Weart on 1976 September 7, Niels Bohr Library & Archives, American Institute of Physics, College Park, MD USA, www.aip.org/history-programs/niels-bohr-library/oral-histories/2779
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Brief, informal, unedited interview on his current views on some questions of cosmology.
What I'm really asking is feel free about your answers because I'm not even quite sure what questions I should be asking. As I've mentioned to you, I'm trying to get some picture of what some of the developments have been in cosmology over the last decade or whatever, in terms of feeling perhaps rather than formal developments. Why don't we start with the big bang and so forth, and what the chairman called today the "established church." Do you think the big bang church has made much progress winning converts, and so forth, in the past 10 to 15 years?
Well, I think the real watershed is in the discovery of the 3 degree black body background radiation. I think that before the discovery of 3 degree black body background radiation, what had a considerable latitude, which kind of cosmology one felt were most reasonable; but now with the three degree black bodied background radiation observer isotropy, I think it's very difficult to avoid the conclusion that the universe went through the big bang early in its history.
You stress this isotropy, which means in fact that it wasn't the original discovery but not until maybe five years ago or whatever. I'm not sure when I would date it that people began to take it very seriously or be very convinced by it.
No, I think people right from the beginning realized this was a very strong clue; that if it had turned out that the background has been spotty then what presumably could have assigned it to some more localized origin, whereas if it really originated in the big bang then you would expect it to be smoother — as it is in fact observed to be.
Do you think that, of course, there's been a lot of other things done in the past ten years. [Inaudible]. Do you think that this has made much of a difference in attracting people to the big bang model?
That's, I think, a difficult question to answer. Perhaps the strongest other evidence comes from the consistency of big bang models with reasonable values of the Hubble Constant and reasonable values of 70 with the observed element that abundances (?) deutronium abundances presently observed. So although the evidence perhaps is not totally compelling, one does get what I would regard as a very reasonable and certainly simple set of assumptions that explained or are consistent with the observed values of the density of the universe, the acceleration parameter.
Do you think it has played the same role as the isotropy that is...
My own... is strictly my own personal feeling. The non-conventional, the people advocating the non-conventional interpretations of cosmology have been forced to adopt what I personally would feel are less and less reasonable positions as the observations accumulated. This is certainly not definitive in a way that if one would like to think in terms of the simplest possible kind of model and explanation for the universe, then I think the kind of alternative used would have been advocated as becoming less plausible than practiced.
What about your own views? You're saying that you more or less agreed with the content... [inaudible]... what sort of the big bang of microwave background that brought you to this view. What did you believe before that microwave background was discovered?
Well, before the microwave background was discovered, it's still very young, I didn't have terribly strong views.
You more or less grew up with the model.
Yes. My own work, I think, had been more concerned with details, establishing scale... [inaudible]... in the universe... [inaudible]... very big picture.
Although if you point out the consistency it becomes very important here. [inaudible]... important part of the whole thing. Voice: Do you feel that there's now quite a strong consensus? Do you agree that sort of an established church and that people who hold alternative views [are] sort of renegade?
Well, I certainly wouldn't say that they are outsiders. There are certain people advocating non-conventional views who are quite prominent in the astronomical community. This meeting here, we could have a number of examples of this. [Inaudible]... is certainly a very outstanding, well-recognized member of the astronomical community and he is taking non-conventional views on most things. The same can be said of Bert Shapiro — he certainly is a member of the establishment in many ways... [inaudible]... observer of the Hale Observatory... [inaudible] ... very non-conventional interpretations. [inaudible]... quite prominent is here whose views are quite non-conventional and certainly being given a fair hearing. So there certainly is a wide range of people who hold non-majority views and are being given a fair hearing. And I think that if only they had more data... [inaudible]... a way that they could probably gather many more.... [inaudible]
Do you think that there is any Caucasian among the non-consensus people?
No, in fact I find that they are the strongest critics of each other.
You mentioned... [inaudible]... Piccard is the only one I'm really familiar with.
Well, there are a number of people, of course, there's Piccard, there's Pier [inaudible], who's worked here with this group.... [inaudible] So there is certain nucleus of non-conventional people centered on.... [inaudible]
But not necessarily agreeing with each other.
Well, I think they agreed reasonably well with each other, although I think they are non-conventional in different ways from, let's say ...[inaudible]... or even ....[inaudible]
Do you think that there's any generational difference? Any way that one can divide the groups whether by age or perhaps observational...[inaudible]
The only distinction, if you want to use that term that I sometimes see and I think it unfair to apply this typification to all of the people involved was what... [inaudible]... remarked during the conference he gave in Toronto a few weeks ago. He said that generally speaking, the conservative seem to.... [inaudible]... more. (Laughter)
... [inaudible]...If I could ask you to be very speculative which I suppose is not unusual for a cosmologist but we had a question today about what would be the likely effect on some of the things ... [inaudible]... talked of ...[inaudible]... very large ray or in general all the extra instruments that we expect to have come along in the next fifteen, to twenty years. Do you think that these are likely to have a strong effect on people's view of the big bang model? Do you think that there is much of a chance that they would return that or a radical shift in it?
Well I think if one looks at the history of science, then one invariably finds that in order of magnitude, improvement in the performance of the major instruments of the science, microscope, telescope, always had a revolutionary impact on science and I'm sure that the more than order of magnitude improvement in revolution that you can get from space telescope it has have a very revolutionary effect on astronomy. I think the only reservation which I would have at this point is that perhaps the step from ...[inaudible]... observation with resolution of perhaps thirty-two seconds to the space resolution perhaps ...[inaudible]... seconds is so large that for a long time we wouldn't really know which problems to look at. In a sense I think it might have been more productive to start with the smaller telescope ...[inaudible]... three resolutions use this to learn which were really the most exciting problems that one could tackle with it ...[inaudible]... and then to go on ...[inaudible]... I think there are a number of examples in the evolution of science of problems that arise if development is too fast. ... [inaudible]... immediate steps were ...[inaudible]... I think for instance in the field that we're discussing here, one of the problems was that QUASAR's perhaps discovered two-thirds and QUASAR's were a hundred times brighter than any galaxy that you could have observed before. People just couldn't believe that kind of energy could be put out by galaxies. Perhaps if ... [inaudible]... galaxies in galaxies had become first which was ten times more luminous than ordinary galaxies, the whole subject would unroll, unfolded in a more natural way, and perhaps many of the controversies that we now see in this field could have been avoided if we had an evolution rather than revolution. I think perhaps the opposite kind of development of relativity, since this was all essentially in the hands of one man, ALBERT EINSTEIN. You get the very logical kind of unfold the hold of relativity and it might be that if relativity had been developed by seven or eight different people competing with each other, that the whole structure might have unfolded in a much less satisfactory satisfaction.
Interesting, I hadn't taught in things of that light of course it's very true the whole opening of radio astronomy, in fact it happened extremely rapidly. We were almost dazzled. ...[inaudible]... say when applying it you can take someone whose blind from birth and show him objects, he must be able to tell you what they are. So use to it. Do you think though, that with this tremendous advance in revolution, the ability to see things, that there is a strong likelihood that big bang theory would become completely displaced or do you think that it's more likely perhaps to simply become more firmly established? Then I think we'd go beyond that.
Well, my own guess would be that the kindest way in which the subjects will eventually be developed would be followed. The basic pattern that we see now big bang ...[inaudible]... will turn out to be correct, but that there will be a number of ...[inaudible]... which we hadn't taught of yet, superimposed. Why I think in the progress of science what usually starts with simple pictures but then eventually it turns out that there are all kinds of ... [inaudible]...
I think you mentioned there are a few problems which people are sort of aware of now, maybe you could name some others and ...[inaudible]... actually whether you think that any of these will perhaps be fruitful sources for extremely upsetting or very radical changes in the next ten years or whatever. For example, there's always a possibility that they will become too new general to these theories such as to ...[inaudible]... particle physics, ...[inaudible]... and so forth remain quite black bodied still, not black bodied, that is black ...[inaudible]... rather are still pretty much there role if not understood. There's always the threat that the ... [inaudible]... problem implies that we have to completely reorganize our ideas of stellar evolution and so forth. Do any of these or perhaps you can name some other likely sources for great changes in the future?
Well, this is obviously a very difficult problem.
I'm asking you questions of the things that people don't normally ask about.
Will one be struck by a lightning bolt, ...[inaudible]... that's the first question you'd want to ask. There is, are there really dark clouds in the sky. I think there are some small clouds in the sky. I don't see any gathering of some of the stars ... [inaudible]... there is tiny beauty about the simplicity of general relativity which I personally associate with. Theories which, if not entirely correct, at least must be awfully close. Getting back to the space telescopes, I think that there are some points which are perhaps not realized widely enough. That is that if one gets above the atmosphere, get into a regime where one can ...[inaudible]... very high resolution obviously one can start the stepping stream between stars ...[inaudible]... but when you are still faced with the problems 28 or 29 ...[inaudible]... stars, there's not very many hope ...[inaudible]... so in order to leisure brightness ...[inaudible]... of such an object one has to observe for many hundreds of hours and in telescopes where time may be worth a million dollars a day, no one is going to get a thousand hours observing time. So I think there is a definite ... [inaudible]... imposed on the rate of progress by the fact that with the data
Final number of ... [inaudible]... arriving.
It's a little bit like the problem of the inter stellar communication. It is quite possibly that someday you might communicate with some extraterrestrial intelligent civilization. It has been said well that perhaps this civilization will be a very dangerous force but it's not just enough to signal use mc2 to us, you have to signal a whole textbook in physics to go with it.
Not to mention the dictionary to go with the textbook in physics.
Data rate limitation of progress and I think one has very severe data rate limitation of the rate of progress with an ...[inaudible]...
So you haven't mentioned the ... [inaudible]...
Very valuable but I think it's not a ...[inaudible]...
You didn't mention the very large ray, I suppose that's where ... [inaudible]...
I'm basically not an astronomer, radio astronomer so I've really not talked quite as much about the impact of a large ray. From what I gather, the improvement merely will be in terms of data rate rather than in terms of performance, in other words ... [inaudible]... telescope in Holland. I think it can do most of the things that the ... [inaudible]... will be able to do but the ... [inaudible]... will be able to do the same things very much faster.
Because it's very large.
Let me turn now to the question that people are starting to discuss today, and that is the Q zero. Do you think that there is any visible progress for some possible consensus about what Q zero is? Over the last ten years?
Well I think there's been a definite shift in people's belief, whereas I think up till two or three years ago, most people I think more on religious than on scientific grounds felt most likely that the universe was ...[inaudible]... and eventually it would ...[inaudible]... again. The evidence gathered in the last two years or so does seem to indicate that one gets a more consistent picture of what is going on in the Q zero spot. The big difference, big advance is in the ...[inaudible]... but up till fairly recently it was taught that one could only learn about Q zero by going to the edge of the universe and there all of the observations become extremely difficult. But during the last two years it has become obvious that there are certain nearby things which contain a great deal of information about Q zero. In particular one has information about Q zero from ... [inaudible]... abundance and it has information about Q zero from the ...[inaudible] ... and clumpiness of nearby galaxies.
Do you think that there are many people finding the results already convincing?
Well, I think that the ...[inaudible]... of values that the average of the values that one is considering in it, this changes significantly, whereas one used to talk in terms of Q zero being half plus or minus 0.5 one perhaps is now talking in terms of 1/10 plus or minus or something.
You mentioned ... [inaudible]...
Well, I don't really see any strong philosophical argument that people have in favor of an open universe. I've seen arguments that people have been in favor of close universe.
Do you think people would prefer to have a close universe?
I think that many people ...[inaudible]... on philosophical grounds would prefer to have a close universe and argue in terms of the kind of allergy between breathing living things breathing universe alternately ...[inaudible]... Perhaps all of this ...[inaudible]... this is not a legitimate kind of comparison to make, but there is one philosophical objection ...[inaudible]... personally feel ...[inaudible]... presumably will go on forever, that is the accreory (?) probably that we should live only 15 billion years after the universe is going to go on forever, was formed, well on the other hand one might counter this by saying, it's during the first million years that the universe is going to be very exciting and after that it's going to be cold and ...[inaudible]...
... [inaudible]... This is what I should have called the modified principle that if you can't have a steady state universe then at least if you look at things over a long enough time scale, one would like to have looking the same. ... [inaudible]... recycling and so forth. You still have a couple of more minutes, if you do. I wanted to ask a little further about whether you feel that there are distinct schools ... [inaudible]... now of people who definitely believe pretty strongly in an open universe? Philosophers of science who believe strongly in a close universe?
I don't think that at this stage there are many people who believe strongly in a close universe. I think that there are some people who fear strongly in an open universe and perhaps a larger number of people who feel that the question is still open.
Do you think that any of these divisions are a long line of ago, or nationality, or type of work that people do?
Gee, no, I can't really see any clear pattern ...[inaudible]... There is obviously ... [inaudible]... in age ...[inaudible]...
It's not clear what conservative means in this context either. It might simply mean skepticism I suppose. Finally, what do you think the chances are for progress in the next ten years on providing at some much more definite consensus that say, now it's pretty clear consensus on big bang. Do you think that ten years from now that there will be a pretty big consensus on the open and closeness of the universe?
That's an awfully difficult question to answer. I think that just from refining the kind of observations that are being made at the present time, one does not likely to arrive at a radical change. In other words, the determination of the HUBBLE concept is ... [inaudible]... to improvement by ordinarily hard work. But I don't think that changing the uncertainty of the HUBBLE from the present value of perhaps fifty percent to five or ten percent will have major impact on this problem. So I think that if we are to make our minds definitely about this, this must be on the basis with information from entirely new direction that people haven't thought of up to now or form a wave length band that had not been properly accessible before.
So that the present approaches, while they help narrow it down, they still do not arrive at a discernible solution for some time.
I don't think that they will. What one really needs is a finding some parameter in the spectra quasar which will allow us to turn them enough so that we could start using quasars for cosmology. Or one might think in terms of some new type of observation that might be made with the next generation ...[inaudible]... far more progress with x-ray telescopes.
Better still, one might want several such things combining at, sort of combining to give us a value for ...[inaudible]...
Or there might be some new technique in nuclear (pause)
Nuclear ...[inaudible]... Some isotope ratio which gives one information on the rate of element formation
Well I have to cut it off so we can get back. You've been very helpful in answering my very vague and difficult questions but let me just repeat that if you have no objections, I'll feel free to use what you've said anonymously. I'll check with you in any case before I ever quote you as having said these things. Is that sort of satisfactory?
No problem, that's fair enough.