What was going on when I was born?

B. Altman & Company, which has opened only seven stores in its 119- year history, could be expanded nationally and its store sites offer the potential for ''significant additional value'' if some of the space is converted to offices and other uses, according to a confidential memorandum to prospective buyers. The bound-volume memorandum, prepared by Morgan Stanley & Company, spells out Altman's history, operations and financial data, much of it for the first time. The Altman Foundation, a charitable institution started by Benjamin Altman, the store's founder, was willed Altman's by the founder and has maintained privacy over its operations. But recently the foundation said it was considering the sale of the company to increase its assets for philanthropic purposes and to satisfy new tax laws. The memorandum was released late last month to a limited number of potential buyers.

Phibro-Salomon Inc., the big Wall Street investment banking and commodity trading house, yesterday announced that, after operating with two chief executives for nearly a year, it had decided to operate with just one. David Tendler, 46 years old, will step down as co-chief executive, a post he had been sharing with John H. Gutfreund. However, Mr. Tendler will continue to serve as co-chairman with Mr. Gutfreund, and chairman and chief executive of Philipp Brothers, Phibro-Salomon's commodities subsidiary. Mr. Gutfreund, 54, in addition to serving as the sole chief executive, will continue as chairman and chief executive of the Salomon Brothers subsidiary, one of the nation's leading investment banking firms.

Navy mine-sweeping helicopters have been sent to the Red Sea to help Egypt clear the waterway of explosives that have recently damaged commercial ships, Defense Department officials said today. The move to dispatch six RH-53D helicopters and spares came in response to a request from Egypt's President, Hosni Mubarak, and at the recommendation of a team of Navy mine-warfare experts. The team has been in the area since last Wednesday, according to State Department officials. Helicopters Loaded Over Weekend According to a Defense Department spokesman, Maj. James Pisciottano, the first transport planes carrying the helicopters took off before midnight for the Middle East. He added that the helicopters would be joined later by a Navy support ship.

The Senate today approved legislation designed to make it easier for women to receive retirement benefits under employee pension plans, either their husbands' or their own. The changes, which would apply to both men and women, have been pushed by both Democratic and Republican legislators and by the Reagan Administration as a symbol of concern for women's rights. President Reagan has said he would sign the bill, known as the Retirement Equity Act of 1984. Under the legislation, a spouse would have to give written permission before an employee could chose a plan that would stop pension payments upon the employee's death instead of continuing the payments to the surviving spouse. Under current law, an employee need not have a spouse's permission to waive payment of those benefits. Usually, payments to the employee will be slightly greater if payments to a surviving spouse are waived..

Officials said yesterday that 18 more children had reported being sexually abused at a Bronx day-care center, raising the total to 30. Edward McCarthy, a spokesman for District Attorney Mario Merola of the Bronx, said interviews by investigators had produced the new reports of abuse at the Praca day-care center, where three employees were charged last week with abusing 12 children. Mr. McCarthy said the children, 4 to 8 years old, named only the three suspects charged last Thursday. All the attacks had occurred since April, he said.

ANCIENT, gnarled pine trees struggling to survive at timberline in the mountains of Nevada and California have grown surprisingly fat, perhaps presaging momentous changes in the landscape of all the Earth. Scientists measuring those trees on the upper slopes of Western mountains believe they provide the first evidence that the growth of the Earth's vegetation is being accelerated by the rise in atmospheric carbon dioxide. Quite apart from its much-discussed climatic implications, the continuing climb in CO2, through its direct effect on photosynthesis, may profoundly transform the balance of nature over the decades to come, many scientists warn.Some species could be driven to extinction. Familiar natural haunts may be taken over by new mixes of grasses and trees, of butterflies and birds. And human diets will be altered along the way.

Thousands of illegal aliens in the New York area are living relatively normal lives by buying bogus documents, using the names of legal residents or simply relying on the inability of the Government to enforce the law, according to government officials and immigration specialists. They can rent apartments, open bank accounts, send their children to school, join unions, collect unemployment payments, get driver's licenses and pay taxes. Whether they get into the country with the help of smuggling networks or with temporary visitor's visas, they often settle down quietly in jobs and homes. A few - no one knows just how many - even manage to get various kinds of public assistance. ''Once aliens get here, they can move around fairly freely,'' said Milton D. Kramer, chairman of the New York chapter of the American Immigrant Lawyers' Association. ''I wouldn't get out the crying towel for them.''

The strike by New York City hospital workers was marked by increasing vandalism and increasing violence at picket lines yesterday. The police said that brick-throwing demonstrators at Long Island College Hospital in Brooklyn had trampled down police barricades and attempted to storm a main entrance on Hicks Street just before noon. Three ranking police officers, including a deputy chief, were injured, none seriously, before the demonstrators were driven back. At least three people were arrested.

''It's a paradox of sorts. People come here with ideals, and this place reinforces their idealism.

When Promising Star pulled into the lead and held under pressure in the fourth race at Aqueduct not long ago, Moreton Binn earned more than $5,000, even though he did not bet on the race or own the winner. The payment to Mr. Binn, who bred Promising Star and the two other horses that finished in the money, was part of an incentive program set up by New York State to spur a revival of the horse breeding industry. Since the program began in 1973, more than $15 million has been given to thoroughbred breeders whose horses finished in the money in New York races. Mr. Binn and his wife, Penny, own Pen-Mor Farms here, 80 acres of paddocks, stalls, tack houses and training tracks built in a former potato field. Last year the Binns earned more than $57,000 - a fraction of their total income from horse breeding - from state stipends.

Small investors are so far putting up little of the money that is fueling the stock surge. (Page D8.) The record stock market rally of last week lost some of its vigor yesterday, although most equities finished higher in a seesaw day. But trading, which had exploded in the previous three sessions, continued its jubilant pace, with the Big Board posting the second heaviest volume in history.

and foes - because of their increasingly vigorous attack on the standard view of how science works. The new school lauds technology as an overlooked force in expanding the horizons of scientific knowledge. The rebellion was led by Derek J. deSolla Price, an eminent science historian at Yale University. Shortly before his death last year Dr. Price landed his most powerful blow in the campaign, arguing that science moves forward not so much through of the insights of great men of genius as because of more mundane things like improved techniques and tools. The big breakthrough of the 17th century was not when Galileo first turned the telescope on the heavens, he argued in a lecture, but when improvements in lens-grinding techniques allowed eyeglass makers to construct the first telescope.