Your people had found a way to break out of the force field.

The only thing he could think of was to make a force field.

It was the sound of a force field being turned off.

There was nothing he could do on the other side of the force field.

If the force field was up, we would know it soon enough.

He finally had to turn the force field off to complete the test.

But the force field couldn't be the only security measure in use.

Once he passed through the force field, there would be no coming back.

I walked up to the edge of the force field.

When they hit the floor, the force field was still active.