New Apple feature sends users back in time

This time, however, the goal is to prevent the universe from collapsing because the file with the big sales presentation has disappeared, or the picture of the family reunion was lost to a faulty hard drive.

No plutonium is necessary to use Apple's Time Machine software, but an extra hard drive is required.

Video: Leopard's Time Machine
Scott Forstall, Apple's vice president of platform experience, demonstrates the new application at the WWDC in San Francisco.

Time Machine will let Apple users running Leopard search for the last time they saved a document, picture or any other file on their Mac, said Apple's Scott Forstall, vice president of platform experience, as he introduced the backup feature at Apple's Worldwide Developers Conference on Monday.

Only around a quarter of all Mac users back up their files, and just 4 percent do so automatically, Forstall said. Time Machine will make it easy for Mac users to set up automatic backups and restore the file they desperately need, he said.

Judging by the audience response, Apple developers at the WWDC were thrilled by the user interface of the Time Machine feature. If users can't find a file in Apple's Finder application, they can click on a Time Machine button to bring up a series of windows stretching over the horizon, with a picture of a black hole off in the distance. Each window represents a day or another fixed period of time, and in order to find the desired file, the user "flies" back in time toward the black hole, with a time line on the right side of the screen marking progress as the days sweep underneath.

The software saves the "deltas," or the changes from one version of the file to a newer version, Brian Croll, director of Mac OS X development, explained in an interview after the keynote presentation. Once the last saved version of the file is located, it can be restored to the main Finder window with a click of the mouse.

"Consumers want it to be automatic and just work," Croll said. The company gathered feedback from consumers about the Backup feature in Mac OS X and came up with Time Machine, he said.

To make Time Machine work, Mac users will need to use a separate HFS+ compatible non-bootable hard drive, Croll said. This can be an external drive for notebook or iMac users, or one of the four hard drives that can fit into Apple's new Mac Pro desktop.

Time Machine is probably the biggest end-user feature Apple showed during its preview of Leopard on Monday, said Michael Gartenberg, an analyst at Jupiter Research. Jupiter's findings also showed that as more and more content is stored on the Internet, computer users aren't backing up their files, even those that are not duplicated on a server. "It's setting a stage for disaster," he said.

Gartenberg pointed out that automated backup software is offered by Microsoft and others, but that Apple managed to make such traditionally mundane tasks more interesting. "People don't smile and laugh when they see (Windows') System Restore," he said.

CNET News.com's Ina Fried contributed to this report.