21.   Some scientists speculate that at least some of the chemical constituents of life originated in the interstellar medium, eventually drifting into the gravitational field of the Earth.

22.   The other five abstained, sending the idea into a limbo that may be as inescapable as the gravitational field of a black hole.

23.   Their gravitational fields are believed to be so dense that they swallow everything that surrounds them, pulling matter toward them in a violent whirlpool.

24.   There were days I wondered whether there was some gravitational field from the outer universe impinging on us.

25.   These analysts say the Web, which is based mainly on open, nonproprietary standards, has achieved sufficient mass to pull everyone and everything into its gravitational field.

26.   Think of it as two planets on a collision course, one that could rip away moons, rearrange orbits, and reorder gravitational fields.

27.   They must be relatively young, no more than a few million years old, as the gravitational field of the galaxy tends to disperse them.

28.   This refers to the apparent brightening of a background star caused by the gravitational field of a massive object passing directly in front of it.

29.   Two types have been known before of these massive objects whose gravitational fields are so intense that even light cannot escape from their grip.

30.   When the gravitational fields of only two objects interact it is easy to calculate the results exactly.