What was going on when I was born?

Secretary of Defense Caspar W. Weinberger said today that neutron weapons were already in production and that the United States would shortly have the capability to deploy them overseas within a few hours of a decision to do so. Mr. Weinberger told reporters at a hastily called news conference in the Pentagon that the decision to produce the weapons had been made ''a couple of weeks ago'' and that assembly of the warheads had already begun. Meanwhile, Mr. Reagan's decision to begin full production of the weapons drew further reaction today from Western European governments. The response was characterized by annoyance at the timing of the announcement. France, however, appeared to accept the decision as unavoidable. (Page A6.)

As an ironic side effect of the air controllers' strike, overall constraints will be imposed on the airline industry -despite passage of the the Airline Deregulation Act of 1978, industry experts said yesterday. They voiced hope that as a result, the airlines' profitability would be enhanced in the coming months. ''There are going to be major changes,'' said John V. Pincavage, vice president and transportation analyst at Paine Webber Mitchell Hutchins. The airlines are expected to continue to operate fewer flights, enabling them to drop unprofitable routes and to attract more passengers to the remaining flights, while making less use of discount fares. At the same time, they are expected to reduce payroll costs and fuel outlays, sidelining inefficient aircraft. All these changes, as Mr. Pincavage put it, ''hopefully will enhance their profitability.''

THE offer is good for only a few more weeks. It is for one of the last remaining ''bargains'' in higher education: 9 percent loans to parents that will soon become 14 percent loans. To date, barely 2,000 of the loans, a new program authorized under the Higher Education Amendments of 1980, have been processed - all but a hundred of them in Massachusetts, which began accepting the loans on Jan. 2, one day after the Federal legislation had gone into effect. Six other states and the District of Columbia put the program in motion in May and four more, including New York State, expect to get the program rolling this month.

PHILADELPHIA FOR years, Aaron T. Beck had to struggle. In the 1970's he published his own journal to, as he puts it, ''bootleg'' reports of his studies that other psychiatric journals rejected. He wrote a textbook, too, to get the word out about the discipline he called ''cognitive therapy.'' Now, in an era when therapeutic approaches form and fade like so many snowflakes, Dr. Beck's cognitive therapy is finally being taken seriously by mental-health professionals. The 60-year-old University of Pennsylvania psychiatry professor's work is reported regularly in both psychological and psychiatric journals and the Federal Government is beginning a major study to compare the success of cognitive therapy to that of another promising approach in treating depression. To the public and behavioral scientists, Dr. Beck has been best known for his development of the Beck Depression Inventory, a scale of key symptoms that has been used almost universally for nearly two decades in the diagnosis of depression. But since the early 1960's, he has devoted a major part of his professional energies to devising his cognitive theory of behavior. In the making of science there is often an emotional component rarely seen by outsiders. In Dr. Beck's case it took the form of remarkable tenacity, that and an uncanny ability to notice themes or trends in human behavior that others might ignore.

Trans-Atlantic flights are delayed and canceled B7 Airlines seek penalties over union picketing B8 U.S. presses foreign governments to keep air routes open B8 Foreign support for controllers laid to solidarity tradition B9 International Price of a Punjab woman: $306 and much sorrow A2 Polish Government sends minister to Solidarity meeting A3 South Korea may free Kim Dae Jung A3 Around the World A7 Bolivian propaganda bears the imprint of Argentina A8 Third world statement condemns U.S. stand on law of sea A15 Government/Politics U.S. says expenses of retired couples rose 10.2 percent in year A10 Few major changes likely soon in nuclear agency's policies A12 Governors attempt to address state-local relations A13 Carol Bellamy criticizes plans to build new subway cars B1 Carey signs bill on arbitration panels for small issues B3 Staten Island G.O.P. leader is hopeful of party's future B5 Industry/Labor Tentative agreement reached between Minnesota and workers A18 Obituaries Alvin L. Feldman, chairman of Continental Air Lines B6 Edward Steese, retired architect and city preservationist B6 Features/Notes Man in the News: J. Lynn Helms, embattled head of the F.A.A. B9 Notes on People B10 Going Out Guide C8 Science Times The body's rhythms send messages C1 Scientific Mind: psychiatrist who won't take no for an answer C1 Education: Student loan program will soon go to 14 percent C1 Photographic chemists in pursuit of faster, sharper films C1 Science Watch C2 Doctor's World: simple tests are still effective C3 Science Q&A C3 About Education C6 General Around the Nation A10 Crowding in U.S. prisons may require building more cells A10 Fires rush across 80,000 acres in five Western states A10 Indian fights deportation with support of neighbors A10 Ex-bank aide pleads guilty in $21 million embezzlement A11 Mother's search results in settlement in daughter's death A13 Americans return to the roads, but keep travels shorter A14 Sixteen maternal cousins declared heirs to Hughes estate A18 Collision of ferry and freighter in Massachussetts injures 16 A18 New York spa's overriding focus is horses B1 Halfway houses try to smooth the path from jail to civilian life B3 Salvation Army to move U.S. headquarters to Jersey B3 U.S. scientists seek better understanding of climate change B4 Independent taxis will survey members on night surcharge B5 Style Notes on Fashion C7 Galanos: luxury, tunics and pants C7 Calvin Klein: suede and midriffs for resorts C7 Arts/Entertainment City plans to transform tenements into artists' co-ops C9 "An Enemy of the People," with Steve McQueen, at Public C9 Pan Asian Repertory stages "Yellow Is My Favorite Color" C10 Herman Gollob leaving Doubleday for Simon & Schuster C11 Two books about Jefferson are reviewed C11 David Grier to make Broadway debut as Jackie Robinson C11 Pat Benatar at rock festival C16 Peking Opera style is marked by intensity of acting C16 Sports Patience, accuracy mark rise of Nelson, new P.G.A. champion C12 Scott wins on knockout in 7th at Rahway C12 Yanks top Rangers, 2-0, as John works 7 innings and wins C13 George Vecsey on Yankees' "Opening Night" C13 Rose breaks Musial's National League hit mark C13 Mets win second-half opener from Cubs on 2 in 13th, 7-5 C13 Terms set for baseball playoffs C13 Carter's hit decisive as Expos down Pirates, 3-1 C14 Orioles top Royals, 3-2, in 12th C14 Matthews steps in as No. 1 Giant fullback C15 Jets' defensive ploy provides happy ending for Salaam C15 Genuine Risk returns to form at Saratoga C15 Chinaglia is angered by Cosmos' slump C15 Editorials/Letters/Op-Ed Editorials A16 Is it safe to fly? Kidporn, outrage and the law Principals and principle Letters A16 Sydney H. Schanberg: a society getting used to crime A17 Tom Wicker: the wrong way to a military buildup A17 Thomas Sowell: Justice and Poverty (first of two articles) A17 Fauzi M. Najjar: sectarian strife in Egypt A17

John Muir & Company, the controversial Wall Street brokerage firm propelled by Raymond L. Dirks from obscurity to prominence, announced yesterday that it will withdraw from the retail brokerage business. The firm said it was conducting discussions with other brokerage firms about selling its retail accounts to them. Muir, in a statement, attributed the decision to ''adverse publicity,'' which had caused ''some deterioration'' in its brokerage business. Muir is currently being investigated by the Securities and Exchange Commission for possible improprieties in some of its underwritings. It has recently been named as a defendant in several private lawsuits.

IF you need to hammer some nails, the best time to do it may be at 3 P.M. If you're running a 50-yard dash, you'll probably do it fastest at 4 P.M. If you're about to have a baby, chances are you'll go into labor around midnight. In fact, practically every system in the body -from the blood, with its rising and falling concentrations of iron, hormones and infection-fighting cells, to the body temperature, heartbeat and blood pressure - has its own rhythm that may fluctuate over a period of seconds, minutes, hours, days, weeks, months or years, according to research here that promises to change present approaches to diagnosis and treatment, and perhaps teaching, travel and work schedules as well. Studies at the University of Minnesota show that, far from being a pseudoscientific fiction, biological rhythms can influence susceptibility to disease, response to therapy and performance on a wide variety of mental and physical tasks. The research, which now involves cooperative studies with scientists in several other states and countries, has raised serious questions about the adequacy of current diagnostic techniques and treatment sch ules, the safety and productivity of shift work and the wisdom of typical American meal patterns.

In a further indication of the Reagan Administration's desire to end the Government's antitrust case against the American Telephone and Telegraph Company, the Justice Department's chief antitrust enforcer said today that the suit would be dropped as soon as a telecommunications deregulation bill is ''pretty well along'' in Congress. The antitrust chief, Assistant Attorney General William Baxter, acknowledged at a news conference that his statement represented a change from his earlier vow to prosecute the A.T.&T. case ''to the eyeballs.'' He said that the deregulation bill would have to include two key amendments sought by the Administration. And he added that the antitrust case would be kept alive until there was assurance of the passage of the legislation by Congress.

Indignation building within him, Frank T. Robbins, unofficial mayor of this resort community, scanned The Racing Form and brooded over his first beer of the day at Barclay's sidewalk cafe. Finally, he exploded in wrath. ''Nostriled - that's what I was, nostriled,'' he said, passing around the picture of a photo finish from the previous afternoon's race to prove that his thoroughbred had lost by even less than a nose. His fellow horseplayers nodded in sympathy, then resumed their concentration on their own statistics.

Ralph E. Bailey, a big sandy-haired man who rose through the ranks of the coal industry to become chairman of the nation's ninth-largest oil company, looked tired and distracted as he sank into an armchair in his corner office. ''I'm ready for a little vacation,'' said the chairman of Conoco Inc. as he gazed off in the distance. Mr. Bailey has not gone unscathed for his performance through all of the merger commotion of recent months. During an hour-long interview, he responded to such criticism as that leveled by Robert Le Vine, an analyst for E.F. Hutton, who said: ''Conoco was a victim of circumstances that the managment handled rather ineptly, but it was a victim.'' Added another analyst: ''If there was going to be a company that was going to fall by the wayside, then it was going to be Conoco. You could never accuse them of having bold leadership.''

The Federal Aviation Administration shut down several trans-Atlantic air routes from six major cities in the United States for three hours today. Secretary of Transportation Drew Lewis said that the reason for the suspension of clearances for flights on the routes was the refusal of some Canadian air traffic controllers, particularly those at Gander, Newfoundland, to handle flights to and from the United States. The Canadians acted in support of air controllers in the United States who have been on strike for a week. Alternate routes avoiding airlanes controlled by the Canadians were quickly approved, but conflicting announcements by spokesmen here and in Ottawa continued to confuse travelers on both sides of the Atlantic as the day and night wore on. Some flights were delayed for hours and some were turned back to European airports. (Page B7.)

Fifty-seven French citizens, whose departure from Iran had been held up by the Iranian Government since last week, arrived here tonight. Their arrival was greeted by a low-key official reception and considerable official relief. For the French Government, which had feared that a situation similar to that of the American hostages would develop, it was evidence that the Iranian authorities had both the intention and the power to carry out their agreement to permit the departure of French citizens who wanted to leave. A second flight, carrying about 60 other Frenchmen, is scheduled to leave Wednesday, according to the agreement. Among them is the French Ambassador, Guy Georgy. Expected to remain in Teheran are two French diplomats to keep the embassy open and 20 to 25 other French citizens, including two Agence France-Presse correspondents.