What was going on when I was born?

Forty years after World War II, strong majorities of both Americans and Japanese regard their countries as friends, with old hostilities apparently receding into the background, according to a New York Times/CBS News/Tokyo Broadcasting System Poll. But the poll found that war memories can still stir powerful emotions on both sides, with 44 percent of Japanese saying they held the atomic bombings of Hiroshima and Nagasaki against the United States and 27 percent of Americans saying they held the attack on Pearl Harbor against Japan. Current trade frictions have not altered their basic attitudes, most people in both countries said. But the corrosive potential of the trade issue was evident anyway. Those who reported that trade had changed their opinions were three times more likely to say that they now felt less friendly about the other country than more friendly.

MANY years ago, scientists deduced that the primary energy source of the Sun and other stars is the fusion of hydrogen nucleii. Experiments intended to verify this fundamental presumption, however, have indicated that something is seriously amiss. In theory, such a fusion reaction would bombard Earth with a stream of ghostly subatomic particles called neutrinos, yet this rich flow of neutrinos has not been observed. A consortium of European institutions has now embarked on the most ambitious effort yet to track the elusive particles, deep in a vast cavern near Rome. If the effort is successful, scientists will be a step closer to answering one of their most puzzling questions: What makes the Sun shine?

Companies BankAmerica cut its dividend nearly in half, to 20 cents a share from 38 cents. The decision will save the company, which posted a $338 million loss in the second quarter, more than $109 million a year. Directors made the decision at a lengthy meeting attended by Federal regulators. [Page D1.] MGM/UA said it was discussing a sale to Turner Broadcasting for $29 a share in cash, or a total of $1.5 billion. The complex agreement would initially give Turner control of the entire company, but MGM/UA would immediately sell off parts for about $500 million, leaving Turner with control of the MGM film library. But Wall Street was skeptical about the deal's prospects. [D1.]

A Boston-based utility holding company is seeking to place a big bet on the troubled Seabrook nuclear project. The company, Eastern Utilities Associates, has offered to buy the shares of four other utilities, which are being urged to sell by regulators. If the unusual bid succeeds, it would increase Eastern's share of Seabrook to 14.2 percent from 2.9 percent, and could put the company in a position to resell extra power to other utilities at a sizable profit. The uncertainty of Seabrook's future, however, makes Eastern's bid risky. The company wants to raise its stake in a project whose value would be reduced to near zero, if it were abandoned, and it has been near that stage several times. In addition, Eastern is making an open-ended commitment to pay another 11.3 percent of the completion costs, no matter how high those rise, in a business that is notoriously unstable.

Two prominent investors, Laurence A. Tisch and Warren E. Buffett, are considering joining with Richard Ravitch, the former chairman of the Metropolitan Transit Authority, and other investors in a move to own the ailing Bowery savings Bank, sources close to the negotiations said yesterday. The bailout of the Bowery, which has been losing money for years, is contingent on an agreement the Federal Deposit Insurance Corporation is expected to reach this week with Mr. Ravitch and the Bowery. Under the agreement the agency would inject an estimated $255 million to $265 million into the Bowery over the next 15 years, sources close to the talks said. The F.D.I.C. agreement calls for a $100 million infusion by an investor group led by Mr. Ravitch. This private investor group would then own the Bowery, which would be converted from a mutual savings institution that is owned by its depositors.

President Reagan today vowed ''a major fall offensive'' to press Congress to act on a series of domestic priorities, including his sweeping plan to modify the Federal income tax code. At a 30-minute news conference, his first since undergoing major abdominal surgery three weeks ago, a vigorous-looking Mr. Reagan made these remarks on a wide range of foreign and domestic topics: * He will continue efforts to reduce Federal spending by eliminating some programs, despite a budget compromise that curtailed spending levels and dismantled only one program. * His other major domestic priorities include a constitutional amendment requiring a balanced budget and a Presidential prerogative to veto individual items within an appropriation bill. * A pimple removed from his nose last Tuesday by a private dermatologist contained a basal cell carcinoma, one of the mildest forms of cancer. * Economic sanctions against South Africa would harm blacks in that country and neighboring countries. He declined to say whether he would veto legislation imposing such sanctions if it came to his desk.

A judge yesterday sentenced the defendant convicted of killing a drama student on a Manhattan roof to life in prison, saying the crime was of ''Shakespearean proportions in its foul and tragic dimensions.'' ''To this day,'' Justice Stephen G. Crane told the defendant, 23-year-old Emmanuel Torres, ''you have never expresssed regret at the murder of this beautiful human being. All you have ever done is boast about it to police, to television reporters and to fellow inmates.'' A jury in State Supreme Court in Manhattan convicted Mr. Torres in June of the slaying of Caroline Isenberg, an aspiring actress and a Harvard University graduate who came to New York City last October to try to get a start in the theater. She was 23 when she was stabbed to death on the roof of her apartment building at 929 West End Avenue.

Two Israeli soldiers and three Lebanese guerrillas were killed today in a shootout in south Lebanon, an Israeli Army spokesman announced. The spokesman described the incident as the biggest shootout in the area since most of the Israeli Army was withdrawn last June. The two slain Israelis were the first Israeli soldiers to die from wounds inflicted in Lebanon since April 24. That was by far the longest stretch of time for Israel to go without a death in Lebanon since the invasion of that country began on June 6, 1982. The total number of Israelis killed in action in Lebanon is now 656.

A NEW controversy over the safety of moderate weight gains in middle age has been set off by a Federal researcher's challenge of the prevailing medical view that lifelong efforts to stay lean are best for health. The lowest death rates are associated with ''leanness in the 20's followed by a moderate weight gain into middle age,'' contends the researcher, Dr. Reubin Andres, clinical director of the Gerontology Research Center of the National Institute on Aging. ''This is, in fact, the weight pattern of most Americans,'' said Dr. Andres, who has garnered the support of some leading gerontologists. At the center of the debate are the venerable height and weight tables compiled by the Metropolitan Life Insurance Company. The company's listings of ''desirable'' weights have been a guide, and not infrequently a source of anguish, for recent generations of body-conscious Americans. The weight ranges in the tables are said to be associated with the lowest death rates.

Sixteen prominent opponents of the South African Government went on trial for treason today. The trial, in Pietermaritzburg, is the largest judicial proceeding of its kind since Nelson Mandela, leader of the outlawed African National Congress, was imprisoned for life in 1964. If convicted, the 16 could face the death sentence. All are leaders of the United Democratic Front, the largest opposition movement outside of Parliament. The accused include the group's joint presidents - Archie Gumede, 72 years old, and Albertina Sisulu, 62, the wife of Walter Sisulu, who was convicted with Mr. Mandela 21 years ago and is still in prison.

Arthur J. Walker has told Federal investigators that when he was despondent over the failure of a family business in 1980, his brother recruited him as a spy, according to statements unsealed here today. The statements were released by order of the judge as Arthur Walker went on trial here on charges of espionage. They were part of legal papers filed by the prosecution, which plans to use them as evidence. Mr. Walker has pleaded not guilty to seven counts of espionage. The statements offer the fullest picture so far of the methods he says were used by his younger brother, John A. Walker Jr., to enlist family and friends in what officials have called the most extensive Soviet spy ring in 30 years. According to the documents, compiled from interviews with the Federal Bureau of Investigation, Arthur Walker said his brother kept maps for clandestine meetings hidden in a wall in his home. The defendant also told investigators that John Walker drove to the Soviet Embassy and parked out front for several days to begin his career as a spy.

The MGM/UA Entertainment Company said yesterday that it was engaged in negotiations for the sale of the company to the Turner Broadcasting System for $29 a share in cash, or a total of $1.5 billion. Even though the complex agreement being negotiated would initially give Turner Broadcasting control of the entire company, it provides that Turner would immediately sell off part of MGM/UA. But Turner would retain control of the MGM film library, which it badly needs, and the other MGM assets at a final cost of about $1 billion. The talks, which were first reported last week, apparently began several days before Ted Turner's attempt to buy CBS Inc. collapsed. Sources close to the negotiations said that the discussions continued throughout the weekend and that an agreement could be signed as early as today contingent on Mr. Turner's being able to raise the necessary funds.