IN December, the European Center for Particle Physics (CERN) approved a proposal to build a particle accelerator known as the Large Hadron Collider (LHC). Physicists hope this machine will help them understand the most fundamental laws of nature. In a recent interview with Monitor writer Peter N. Spotts, University of Texas physicist Steven Weinberg explained why United States participation in the new project is important. Dr. Weinberg, a Nobel laureate, is also the author of ''The First Three Minutes'' (Basic Books, 1977), about the origins of the universe, and ''Dreams of a Final Theory'' (Vintage, 1992, 1993), about physicists' quest to understand the forces of nature. Excerpts from the interview follow.
In ''Dreams of a Final Theory'' you write of a breakdown in a centuries-old compact between scientists and society. What is that compact?
The motivations of scientists and the people who support them have always been somewhat different. Leonardo da Vinci, in order to get support for his work, had to offer to the Duke of Milan that he was going to build engines of war. Occasionally you find enlightened monarchs who supported pure research, but almost always they had some practical applications in mind. That's all right; nobody owes us a living. But the compact was a kind of tacit understanding that by supporting basic science -- the science that didn't have any immediate practical payoff or any foreseeable practical payoff -- benefits would still flow to society. In Congress and in the public that Congress responds to, you find that attitude less and less.
What evidence do you see of that breakdown?
I spent a lot of time campaigning for the [Superconducting] Super Collider [SSC]. This was a big project, and it was a fair question whether it was worth the money. I don't say that everyone who disagreed with me was hostile to the aims of science. But a lot of them were. A lot of congressmen showed that they simply had no use for science, except where it could promise some practical application. For example, I was on a radio show with [a congressman]. He was saying that he's not against science, but he felt we have to get our priorities straight. And I said, Well, what are your priorities? The super collider aims at discovering the most fundamental laws of nature. Isn't that something that interests you? He said: No, it doesn't. Well, that's really laying it out!
What will it take to restore the compact?
In this respect, the Republicans, although generally tighter in their support of public goods like the arts, are better than the Democrats because their [the Republicans'] ideology is against public support for applied research. To certain schools of Republicans, the only valid role for the National Science Foundation, for example, is to support pure research, because supporting applied research is intervening in the economy. And that's a no-no. So the recent election, although it's very bad for those of us who think in terms of spending on all kinds of public goods like welfare and the arts and so on, may not be such a bad thing for basic science. But if the Democrats and the Republicans engage in a budget-cutting competition, then science is going to lose. The thing that killed the supercollider was the intense concern about the deficit on the part of freshmen congressmen in 1993.
Why should the US participate in CERN's Large Hadron Collider project?
High-energy physics has always been run on a basis that all the big machines were open to research proposals from all countries. Already the single largest national contingent at CERN is American, and we didn't help build CERN. The quid pro quo always was that there were a lot of Europeans at Fermilab and SLAC [the Stanford Linear Accelerator Center], which were competitive with CERN. When the LHC becomes the only front-line machine in the world, and there's nothing in America that's comparable, Americans are not going to be very welcomed at the LHC if we haven't contributed to building it.
Another reason to help is that it will make a huge difference in the pace of the research. If America and Japan and similar countries don't help, the machine won't be up to full power until well into the 21st century. If we help, it will be working at full power in the first few years of the 21st century.
What should our participation in the LHC look like?
I presume that some of the help would be in kind; we could make some of the magnets. These magnets are so powerful that copper flows like butter in their magnetic fields. And the energy stored in the magnetic fields is like the energy in TNT. So they have to be designed with a certain care. This is high-precision, and yet these things are 60 feet long. So it's a superb exercise in technology.
Of course we're not the only ones being asked to help. There's the Japanese. I think that the CERN people have done it just right. I went to Japan during the period when we were trying to get the supercollider built. By and large I found a lot of sympathy for the supercollider project. The biggest single issue that kept coming up was: We don't want to get into this if we don't know that you're going to carry it through. And as it turned out, they were right -- except that if they had gotten into it, we probably would have carried it through. The Europeans have said: We will go ahead without non-European support, although it [the LHC] will be slower and less powerful; since we're definitely committed, now please really consider it seriously. That was very smart; we should have done that. And that may be what attracts the Japanese to participate, where they didn't participate in the SSC.
You've written that if the supercollider fell through, the US could lose a generation of physicists to Japan or Europe. Would we? In this age of Internet, shouldn't where experiments take place make little difference?
As a theorist, leaving aside the fact that I am an American and a Texan, I don't really care that much whether the work is done in Geneva or in Texas. It makes a big difference for experimentalists. You can't learn to be an experimentalist without experience under mentors, and when you lose the tradition you can't easily start it up again. You can learn to be a theorist sitting on a rock with just a bag of books.
But even theorists are affected by the decision. The European accelerator is not going to be the equal of what the supercollider would have been. It will have less than half of the power. And instead of being finished in 1998 or 1999, when the supercollider would have been finished, it will be partly finished in 2004. I was speaking today to a young physicist at Harvard -- also a theorist -- who was telling me that he felt his career would be largely over by the time the European accelerator was up to full power.
Without the stimulus of new experimental results, there's not going to be much for theorists to do.
If you could alter anything in your book ''The First Three Minutes,'' what would it be?
I think I would have expressed a little more skepticism about the simple picture of the universe starting in a singularity with a uniform expansion that's been expanding like that ever since, and that it definitely started between 10 billion and 20 billion years ago.
The picture has gotten much more complicated. There are very plausible theories -- I'm particularly thinking of the work of Andre Linde at Stanford, but there are a lot of people following up these ideas -- that have a much larger picture, in which our big bang is really just a little bang and that there are bangs like this going on all the time, more or less at random, in an eternal universe.