Parents, politicians and social scientists say too much violence, sex and vulgar language routinely appear in movies, television shows and recordings accessible to children. It's an age-old concern, but now the government appears ready to intervene. Congress is considering legislation that would require the broadcasting industry to create a universal ratings system for TV programs, and manufacturers to produce new TV sets with the technology to let viewers block out offensive programs. Broadcasters would have a year to create the ratings system; then the government would step in and devise the standards. The entertainment industry traditionally has resisted what it sees as censorship, but now it may be willing to respond on its own, rather than have government impose guidelines.