STANFORD, Cal.--Stanford University has announced plans to build a $60 million underground addition to its linear accelerator to hold an energy beam of 100 billion electron volts--three times more powerful than any other in the world.

The addition, called a single-pass collider, will create two beams of 50 billion electron volts that collide with a force of 100 billion volts. The next largest facilities are in Hamburg, West Germany, and produce about 30 billion electron volts each.

"The goal of the new project is to find out how many forces there are in nature," Burton Richter, a Nobel laureate and the Stanford professor who designed the project, said recently.

Traditional physics theory holds that there are four independent forces in the world: gravity, electricity, nuclear force, and the weak force (radioactivity).

But some theorists today believe that electricity and radioactivity may be different manifestations of the same force. If this is so, the collider would show it Richter said.

The current Stanford linear accelerator attracts physicists from all over the world. At any one time there are usually 350 physicists at the accelerator, a spokesman for the facility said.