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Full Idea
Gravity is an odd sort of force, not least because it only ever works one way. Electromagnetism attracts and repels, but with gravity there are only positive masses always attract.
Gist of Idea
Gravity is unusual, in that it always attracts and never repels
Source
New Scientist writers (Why the Universe Exists [2017], 05)
Book Ref
New Scientist writers: 'Why the Universe Exists' [John Murray 2017], p.99
A Reaction
This leads to speculation about anti-gravity, but there is no current evidence for it.
13593 | Newton showed that falling to earth and orbiting the sun are essentially the same [Newton, by Ellis] |
13605 | Gravity isn't a force, because it produces effects without diminishing [Mayer] |
20636 | Newton is a special case of Einstein's general theory, with an infinite speed of light [Einstein, by Close] |
21236 | Instead of gravitational force, we now have a pervasive gravitational field [Farmelo] |
21167 | Gravity is unusual, in that it always attracts and never repels [New Sci.] |