Edward Teller, the key figure in the development of the hydrogen bomb, is once again feuding with a number of his fellow scientists. President Reagan has the right and courageous idea when it comes to nuclear defense strategy, says Mr. Teller.
The still vigorous and articulate Teller argues that scientists who have been criticizing Mr. Reagan's call for a program to counter Soviet missiles with new defensive measures either are not informed about the latest technologies or are victims of ''group think.''
The feisty, bushy-browed physicist is widely believed to have exerted a major influence on Reagan's thinking on nuclear defense. Teller acknowledges only that he tries to have an influence and that the ideas recently put forth by the President run parallel to his own. Teller said that in the course of his first meeting with Reagan, in 1966, he suggested that Reagan visit the Lawrence Livermore Laboratories in California.
''He did come in, and we gave him a detailed briefing on what we were doing, '' said Teller in his heavy East European accent. ''I found him remarkably open-minded, and he picked up ideas very fast.''
The Hungarian-born Teller is close to the President's science adviser, George A. Keyworth, with whom he worked at the Los Alamos scientific laboratories. According to Science magazine, in August of last year Dr. Keyworth arranged a meeting for Teller with Reagan at which Teller recommended a ''crash program to develop space-based, X-ray laser weapons.''
In an interview, Teller said he could not discuss such details because his research work is classified. This is a scandal, he says, because the Soviet Union already knows much about what the Americans are doing in the field of defensive technologies.
The critics among his colleagues, he continues, are in some cases attacking ideas that actually are not his, such as recommendations made by a private group called High Frontier.
High Frontier proposes that a system of several hundred satellites be put into orbit some 300 miles above the Earth. Each satellite would be armed with 40 to 50 small, nonnuclear rockets capable of intercepting Soviet missiles.
What Teller will say is that he would prefer a multilayered defense. He denies that he is advocating a ''massive development in space.''
''High Frontier can be done for $100 billion dollars, let us say,'' said Teller. ''But the Soviets can get rid of High Frontier for $10 billion.''
Although Teller will not publicly acknowledge it, other scientists say that what he is advocating, among other things, is a laser that would use X-rays produced by nuclear weapons, based on space satellites.
The director of High Frontier, retired Gen. Daniel O. Graham, describes Teller as an old friend who was frequently consulted by High Frontier. But General Graham rejects the X-ray laser idea.
''Here's the rub,'' says Graham in one of his publications. ''The X-ray laser , dependent as it is on a nuclear explosion for its power, must destroy itself to operate. If the Soviets should launch a single missile at the X-ray laser satellite, it could defend itself only by destroying itself. It would not then be available to defend anything else.''
One of Teller's chief critics at the moment is Richard Garwin, the physicist who made the first detailed design of the hydrogen bomb, at Teller's request.
''We shot it more or less as Garwin designed it,'' said Teller, who describes Mr. Garwin as ''a very brilliant physicist.''
But Teller contends that a number of brilliant, lesser-known younger physicists who are working on defense technologies led him to change his thinking over the years.
''I'm an old stick in the mud,'' said Teller. ''When I hear about these radical ideas, I usually say, 'Go away. It won't work,' the same as Garwin. But my young friends come back and say, 'These are the details, these are our proof.' ''
Garwin argues that research already done on nuclear defenses shows that the Soviets can counter any defensive system in space, with space mines, for example , at a cost much lower than that which it would take to build the system. An attempt to destroy Soviet mines would lead to war in space as a prelude to war on Earth, he says.
''A complete defense is very difficult,'' said Teller. ''I don't even think we can do it. But . . . by putting down several layers - a multilayered defense - if the Soviets don't know whether they will succeed or not, then they are much less likely to attack. The Soviets don't like to take chances.''