Stephen Hawking was never “briefly free of the gravity normally limiting his motions.” (When boundaries flew away: Slipping the surly bonds of gravity, May 18 issue).
In the article it states that, “Although he was weightless for about a minute, actually in free-fall…” In free-fall he was being accelerated toward the earth with the full force of gravity. He was weightless because the 727 flew a path that gave no resistance to the acceleration of gravity. Think of weight as resistance to acceleration.
The name on the 727, “Zero-G,” causes confusion. I hope it does not cause confusion in the thinking of Stephen Hawking.
JAMES F. JACKSON