Defense Intelligence Reference Document Negative Mass Propulsion

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1. Introduction
If we extend the law of gravity to negative masses, but hold onto the equivalence of
inertial and gravitational masses, we have to distinguish between the following four
cases, if a test particle is placed near a gravitational field producing mass (Table 1):
Table 1. Interactions
Case Gravitational field Mass of test Motion of test
producing mass particle particle
1 + + attraction
2 + - attraction
3 - + repulsion
4 - - repulsion
Under the principle of equivalence if a negative test mass particle would be placed in
the gravitational field of earth, it would not fall upwards, as happens in science-fiction
antigravity machines. A test particle, regardless of whether it has positive or negative
mass, would there always fall down. It would fall upwards only if placed in the field of a
large negative mass.
A somewhat different situation arises if both masses, the field producing mass and the
mass of the test particle, have the same absolute value but are permitted to have
different signs. There we have to distinguish between the cases shown in Figure 1.
Ca:;o
2 -0 ---(-) '
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3 O· () .
-·-----
4 --(-) 0·._L ____ -~-
Figure 1. Forces
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