CHICAGO — The discovery that a bizarre particle travels between the real world of matter and the spooky realm of antimatter 3 trillion times a second may open the door to a new era of physics, Fermilab researchers announced Monday.

The incredibly rapid commuting rate of the B sub s meson particle had been predicted by the Standard Model, the successful but incomplete theory aimed at explaining how matter and energy interact to form the visible universe. After 20 years of trying, scientists have now confirmed the rate, providing strong evidence for the theory.

The monumentally precise technology developed to measure the meson's back and forth dashes also may open the way to discovering a new family of fundamental particles and possibly a set of new forces that could be harnessed for technological applications, physicists suggested.

The discovery comes at a time when the future of Fermilab, located near Batavia, Ill., is in doubt. Its huge 4-mile circular Tevatron particle accelerator may be forced to close by 2010 if Congress does not approve construction at Fermilab of a multibillion-dollar, 18-mile-long International Linear Collider.

Without the collider, the United States would lose its lead position in high-energy physics discoveries to Europe, where a new accelerator seven times more powerful than the Tevatron is to start up within two years at a site on the Swiss-French border.

The meson finding shows that Fermilab, which began operations in 1967, is still capable of making breakthrough discoveries. Scientists there discovered two of the most fundamental particles, the bottom quark in 1977 and in 1995 the top quark, one of the constituent particles of protons, which form the nuclei of atoms.

Raymond Orbach, undersecretary for science with the U.S. Department of Energy, called the breakthrough "a triumph for Fermilab."

"This remarkable tour de force details with exquisite precision how the antiworld is tied to our everyday realm," he wrote in a statement. "It is a beautiful example of how, using increasingly sophisticated analysis, one can extract discovery from data from which much less was expected."

For all that scientists have learned about the universe it is still a mysterious place. Immediately after the Big Bang some 13 billion years ago equal amounts of matter and antimatter formed. Much of it quickly acted to annihilate the other, but for little-understood reasons a bit more matter than antimatter survived, providing the universe with the planets, stars and galaxies visible today.

Particles that bridge the two worlds, such as the B sub s meson, normally don't exist on their own but can be created in the great collisions generated by particle accelerators, which attempt to duplicate conditions close to the Big Bang. Studying the particles helps scientists understand the evolution of the universe.