What was going on when I was born?

A research group's findings that the United States could eliminate oil imports by improving energy efficiency have stirred considerable debate. The Energy Productivity Center of the Mellon Institute said in an unpublished study that the United States could eliminate oil imports by the year 2000, and save billions of dollars, by improving the efficiency of the equipment used to convert fuels to energy. ''We don't see any energy scarcity in our projections,'' said Roger Sant, director of the Washington-area research organization. The study calculates that the United States could cut the amount of money it pays for foreign oil from about $80 billion in 1980 to an average of $15 billion annually in the 1990's, to nothing at all after the year 2000.

The Art People column in Weekend on Friday incorrectly reported the time of a scheduled memorial service for the art dealer Julien Levy at the Cooper Union, Eighth Street and Astor Place. It will be held at 4 P.M. on Friday, April 24.

MILWAUKEE LINGERING near the foul line, Bob Lanier had vaguely heard his name being called. The Milwaukee Bucks' center - a striking, bearded man, 6 feet 11 inches tall, broad as Buddha - looked up. Quinn Buckner, a Bucks guard, was dribbling the ball hard with one hand and pointing with the other. ''Over there,'' shouted Buckner, who had called a play. Lanier snapped out of his reverie and moved across the gleaming floor of Milwaukee Arena, and planted a pick to set up the play; he was back in the game.

An outsized mouthful of pearly white teeth gleams from the magazine page. ''Introducing Advanced Formula Crest,'' the advertisement declares. ''Now, get fewer cavities with Crest than you ever got before.'' In a recent spate of television commercials, ''what's new'' at the neighborhood drugstore turns out to be ''new improved Colgate,'' with a ''100 percent pure'' mint taste. ''Mmmmmm,'' exclaims the customer. ''Colgate, better than ever.''

Leonid I. Brezhnev, the Soviet leader, flew to Prague today amid intense speculation here and in Eastern Europe that a decision by Moscow on whether to intervene in Poland would come in the next few days. Mr. Brezhnev was met at the airport by Gustav Husak, the leader of the Czechoslovak Communist Party, and the two men met again later to exchange ''views on some international problems,'' according to the Czechoslovak press agency, CTK. In Washington, officials said that President Reagan had sent a strongly worded message to Mr. Brezhnev on Friday that was intended to underscore the seriousness with which the United States viewed Soviet military moves in and around Poland. (Page A10.)

The final 1980 Census Bureau figures for New York City show a sharp decline in the city's white population, a moderate rise in blacks and a substantial increase in Hispanic people. Because of some confusion in the way the census counted different racial and ethnic groups, and because there are thousands of people whom the city asserts the Census Bureau missed, it is possible that Hispanic people have surpassed blacks as the city's second-largest ethnic group, some city and Federal officials believe. The citywide total for 1980 was 7,071,030, a decline of 10.4 percent from the 7,895,563 recorded in 1970. The figure differed only slightly from the 7,015,608 reported last Dec. 24 as the preliminary total.

The Toyota Motor Company wants the United States Government and Detroit to decide on specific ways to rejuvenate the American auto industry before asking the Japanese auto makers to take any steps to help, according to Shigenobu Yamamoto, executive vice president of Toyota. In an interview, Mr. Yamamoto also said that his company and the Ford Motor Company had reached a preliminary agreement to build jointly a recreational van-type vehicle but that the two companies had not yet agreed on specific production plans. Before Toyota or other Japanese auto companies begin any ''voluntary'' restraint of their shipments to the United States, which reached 1.8 million vehicles last year, the United States should agree upon the following measures, Mr. Yama@moto said: - American auto makers should develop programs to modernize and retool their production facilities to expand their capacity to make smaller, fuel-efficient cars. - The United States Government should pass preferential tax legislation to encourage investment by Detroit and should eliminate ''excessive regulations'' on the industry.

Magic Johnson reached into his bag of tricks and came up with air today - an ''air ball'' that never reached the basket with five seconds left - as his Los Angeles Lakers, the defending National Basketball Association champions, were eliminated by the Houston Rockets, 89-86. Johnson, the charming young man who carried the Lakers in the game that clinched their championship last spring, had complained about teammates' jealousies this week. But he gave them nothing about which to be jealous today. Johnson turned in a dreadful performance, making two of 14 fieldgoal attempts and six of 11 foul shots, including two missed free throws with 30 seconds left that would have greatly affected the outcome. Fifteen seconds later, Mike Dunleavy hit a 15-foot jump shot that gave the Rockets the lead for good.

In the last three years, more than 600 ground water wells have been closed in the New York metropolitan area because of contamination by chemicals, and public health and environmental officials fear that thousands more may be jeopardized in coming years. The ruined wells are only a small fraction of the hundreds of thousands thought to be in use in New York, New Jersey and Connecticut. But the officials say that the threat could spread as ''plumes'' of toxic organic chemicals move slowly through ground water aquifers in the three-state area. Tainted wells shut since 1978 include at least 455 in New Jersey, 50 in Connecticut, 51 in Putnam County, 23 in Nassau, 19 in Suffolk, 20 in Rockland, and 11 in Westchester. In addition, several hundred homes in the Town of Babylon on Long Island have been connected to municipal water supplies because of well contamination, according to Dennis Lynch, Babylon's Commissioner for Environmental Quality.

Proud Appeal outlasted Cure the Blues for a nose victory at Aqueduct yesterday in the $83,400 Gotham, ending the unbeaten streak of one of the early Kentucky Derby favorites. As Proud Appeal and Cure the Blues matched bobbing heads through a sloppy stretch that was labeled fast, the three extra pounds carried by Cure the Blues apparently became a factor. The missing ingredient at the finish line of this one-mile race, billed as a confrontation of three Derby contenders, was Noble Nashua. He was third, 8 1/2 lengths behind Cure the Blues. The remaining three horses were well up the track.

President Anwar el-Sadat of Egypt was reported today to have cleared the way for the presence of American troops in a contemplated peacekeeping force between Israel and Egypt. Mr. Sadat was also reported to have offered to be flexible in allowing American forces the right to use Egyptian military facilities to deal with crises in the Middle East. Secretary of State Alexander M. Haig Jr., who said that he had ''extremely fruitful talks'' with Mr. Sadat at the President's villa outside Cairo this morning, was reported by American and Israeli officials to have discussed Mr. Sadat's apparent openness during his meeting here later in the day with Prime Minister Menachem Begin and other Israeli officials. Talks With Israelis More Difficult Mr. Haig, however, was said to have had a more difficult time in his session with the Israelis than he did with Mr. Sadat. According to participants in the meeting, Mr. Begin strongly voiced his opposition to the projected American sale to Saudi Arabia of five Awacs electronic surveillance aircraft, as well as of equipment that will allow American F-15 fighters purchased by the Saudis to have greater range and firepower.

''This is a switch.'' - Vernon E. Jordan Jr. of the National Urban League visiting Ronald Reagan, who had called on him when he was recuperating from a gunshot wound.