What was going on when I was born?

Orders for durable goods plunged 2.8 percent in July as both the military and civilian segments of the economy suffered declines, the Commerce Department said today. It was the biggest drop since March and provided further evidence that the hoped-for rebound in economic activity is not on the horizon, economists said. Separately, the Government said that consumer prices rose two-tenths of 1 percent in July, the same increase as in June and May. And prices in the New York-northeastern New Jersey metropolitan area rose one-tenth of 1 percent. [Page D3.] Durable goods orders have been weak for most of the year. With the military segment removed, orders have posted an anemic one-tenth of 1 percent monthly rise since January.

The Department of Health and Human Services is drafting a report to Congress recommending a major change in the way the Government pays physicians under Medicare, the health insurance program for the elderly. According to department officials, the report suggests that the Government establish standard Medicare payments for 6,000 procedures. The fees would be based on historical data showing how much doctors have charged, or how much Medicare has paid, for the services. This system would bring greater uniformity into payments under Medicare. At present there is, in effect, a different fee schedule for each doctor, and payments are calculated according to a complex formula taking account of the physician's customary charges as well as the prevailing charges in an area.

An item in the Sports People column yesterday on the Masters Games in Canada incorrectly reported the amount of a Government grant to the games.

President Reagan, in a speech that reinforced the Administration's toughening posture toward the Soviet Union, today strongly defended plans to develop a defensive weapons system in outer space. His remarks were a strong reaffirmation of his commitment to the weapons project, and they came after a week of sharp exchanges and other developments that appear to have further chilled relations between the United States and the Soviet Union. Speaking here at a fund-raising affair for the Republican Party of California, Mr. Reagan said the proposed Strategic Defense Initiative, widely known as Star Wars, offered ''us a way out of our nuclear dilemma, the one that has confounded mankind for four decades.''

For the first time, changes in the acidity of rainfall have been directly linked to changes in pollution emissions hundreds of miles away, according to a new scientific report. The existence of such a correlation has been the subject of intense debate, and drafts of the report, which is being published today, have already stirred more controversy. Government experts questioned its conclusions, while other scientists said the report represented a major advance in acid-rain research. The Reagan Administration has maintained that too little is known about acid rain to justify costly efforts to contain it.

''All the 21 people are the shareowner of this ticket and will get the prize.

The Ford Motor Company plans to reduce its white-collar work force by 20 percent, or about 10,000 workers, over the next five years, company officials announced today. While Ford would not rule out the possibility of layoffs, it said it expected most of the cutbacks to come through attrition, a retirement incentive program and a voluntary termination plan. ''We are developing a new plan, which includes provisions for early retirements and voluntary termination, and we plan to put it into a test basis soon,'' said William T. Peacock, a spokesman for Ford. Details of the plan should be available to employees by the end of the year, he said.

International President Reagan strongly defended plans to develop a defensive weapons system in space. A Republican fund-raising speech by Mr. Reagan in Los Angeles reinforced the Administration's toughening posture toward the Kremlin. [Page A1, Column 6.] Washington's protest over Moscow's purported use of a possibly hazardous chemical to track the movements of Americans in the Soviet capital was not intended to ''sabotage'' the scheduled November meeting in Geneva between President Reagan and Mikhail S. Gorbachev, Administration officials said. [A6:1-2.]

If Warner Communications Inc. and the American Express Company had attempted to sell Warner Amex Cable Communications as recently as three years ago, they would have been hard pressed to find a buyer. Gone were the euphoric days when cable system operators envisioned a host of new pay-TV services to add to their existing monthly fee income. Instead, many media companies found themselves losing money after investing heavily to lay cables in new markets. Nowadays, however, cable operators have good reason to be optimistic. Rate deregulation has made the business more attractive; companies are getting increasingly sophisticated in marketing cable services to consumers, and the years of heavy investment are coming to an end.

In the end, the vision that tantalized millions of New Yorkers materialized for a group of men who had come to America in search of the American dream. Last night, the only identified winners of a lottery jackpot of $41 million, the biggest in the history of the United States, were a pool of 21 factory workers, most of them recent immigrants. They work at Hantscho Inc., in Mount Vernon, N.Y., but they have come here from such countries as China, the Dominican Republic, Poland, Trinidad, Thailand, Yugoslavia, Paraguay and Hungary. 'Cross Section of America' ''These guys are like a cross section of America, with every ethnic, racial and religious group represented,'' said Karl Wallburg, vice president for manufacturing at Hantscho, which makes printing presses, and himself an immigrant from Germany. ''It's wonderful, like a fairy tale, and all of us here, even those who didn't win, are on cloud nine.''

The SCM Corporation's stock price jumped $1.125 a share yesterday, to $64.125, a day after the Hanson Trust P.L.C. said it would offer $60 a share for the chemical and typewriter company. The stock's continued strength above the proposed offering price reflected the belief of analysts and investors that Hanson's bid was too low and that it might be sweetened, or that another bidder might emerge. SCM had soared by $8 a share on Wednesday before the announcement of the offer, closing at $63. SCM said yesterday that it was studying the unsolicited $755 million offer with its financial adviser and its law firm. In an interview yesterday, Paul H. Elicker, SCM's chairman and chief executive, declined to comment on the offer. But he left little doubt that SCM did not view it as attractive.

Companies Ford plans to eliminate 10,000 white-collar jobs in the next five years, reducing its salaried work force by about 20 percent. Ford said most of the cutbacks could be made through attrition, retirement incentives and a voluntary termination program, but it would not rule out the possibility of layoffs. The move was seen as part of a growing cost-consciousness in Detroit. [Page D1.] A rescue of Community Savings was reported to be near completion. Investment banking sources said the bailout's first stage could be completed in time to avert a default by the thrift unit's real estate subsidiary. The plan being assembled by Dean Witter Reynolds reportedly would involve a cash injection and then the sale of Community and its subsidiary. [D1.]