Antigravity: a Down to
antigravity is usually associated with science fiction novels, an early
example of which is H.G. Wells' The First Men in the Moon (pub.
1901) where Cavorite, a gravity defying substance, forms the basis of
his spacecraft's reactionless drive. However, the most celebrated
antigravity device in science fiction is probably James Blish's
'spindizzy,' the gravitron polarity generator mentioned in his Cities
antigravity be more
than just science fiction? Carrying out a Google search on antigravity
revealed many sites devoted to the subject from a true believer's
perspective. Could it be that all we have to do is reverse the polarity
of the gravitational field (or some such thing), and the stars are
ours? The purpose of this article is to examine the likelihood of
antigravity being possible.
What is Gravity?
investigation with an outline of what scientific inquiry has revealed
concerning the force of gravity, for when we understand the nature of
gravitation we will be in a better position to assess the probability
of antigravity's existence.
is one of the
fundamental forces of Nature — the force of attraction existing between
all material bodies. Isaac Newton's Law of Universal Gravitation was
the first successful attempt to scientifically describe gravity and can
account for most of the observed planetary motions and tides. Indeed,
even in modern cosmology there are many instances where Newtonian
calculations are still perfectly adequate.
sufficiently accurate for most applications, Newton's work has been
surpassed by the more complete understanding of gravity expressed in
Albert Einstein's Theory of General Relativity that describes
gravitation as a distortion in the space-time continuum caused by the
presence of matter.
analogy of this
conception of gravity can be illustrated using a thin sheet of rubber
whose two-dimensional surface represents three-dimensional space. When
spherical weights of different mass (representing the Sun and planets)
are placed upon the sheet they create depressions in its surface — the
more massive the sphere, the deeper the depression, with the steepness
of the depression's slope corresponding to the strength of the
be seen, gravity,
unlike electromagnetism, is always attractive because of the way it
deforms space. It does not have two possible charges — that of
attraction (between unlike charges), and repulsion (between like
charges). Consequently, antigravity can't be generated, as there is no
polarity to reverse.
difficulties, a number of claims have been made concerning the
detection of anti-gravitational effects, and these shall now be
An article in New Scientist (September 21, 1996) reported the
work of Eugene Podkletnov, a researcher into high temperature
superconductivity at the Tampere University of Technology in Finland.
to the report,
Podkletnov found that objects lost up to 2% of their weight when placed
above a ring-shaped superconductor spinning at 5000 rpm, and suspended
in a magnetic field. Unfortunately, this claim is surrounded by
controversy. A paper was to be published in the October issue of the Journal
of Physics D Applied Physics, published by the British Institute of
Physics, however, according to New Scientist the paper was
withdrawn after Tampere University issued a statement denying all
knowledge of antigravity research. Indeed, the only organization that
seems to have taken these claims seriously is NASA which has spent
considerable time and money trying to replicate the results with little
Podkletnov's claim seriously enough to attempt to replicate his work —
except NASA. NASA has spent four years and more than $1 million
attempting to repeat it. So far the results have been "inconclusive."
In this case, that means researchers measured a weight change of only
two parts in a hundred million, which they admit could have just been
an artifact of the measurement. Any weight reduction at all would be a
revolutionary discovery, but small effects always raise questions about
flaws in the experiment." (Robert Park: Voodoo Science, page 137)
Other similar claimants include Hideo Hayasaka and colleagues at the
Faculty of Engineering, Tohoku University, Japan who claimed to detect
an anti-gravitational effect in spinning gyroscopes.
consisted of dropping a gyroscope spinning at 18,000 rpm in an airtight
container so that it passed between two laser beams that recorded the
time taken to fall the 6 ft separating them. After ten runs the team
claimed that the spinning gyroscope took approximately 1/25,000th of a
second longer to fall the same distance than when it was stationary.
did not survive independent scrutiny — the experiment was repeated with
greater sensitivity at the Joint Institute for Laboratory Astrophysics
in Boulder, Colorado, with negative results.
Is it possible to invent some kind of material like Wells' fictional
cavorite that could shield objects from the force of gravity? It's
difficult to see how this could be done using conventional matter
because matter itself is responsible for gravity.
against a cavorite-like substance is that it would violate the
conservation of energy, a fundamental natural law, by enabling us to
construct a perpetual motion machine — all that would need to be done
is place this miraculous material under one half of a huge wheel.
one side of the
wheel is always lighter than the other it will be continuously
overbalanced, and so be in perpetual motion, thus producing energy out
of nothing — a violation of the first law of thermodynamics.
Negative matter is a hypothetical form of matter first proposed by
Hermann Bondi in Reviews of Modem Physics (1957). This form of
matter is negative in the sense that its mass is opposite in sign to
that of normal matter and, strangely enough, the laws of nature do not
appear to forbid its existence.
unusual properties of
negative matter, if it exists, could enable us to construct an
antigravity engine. In theory this can be done because the
gravitational field of a negative matter object would repel all other
objects (both negative matter and positive, or ordinary matter), while
the gravitational field of a positive matter object would attract all
other objects, including those of negative matter.
negative and positive matter produces a rather interesting effect — if
a sphere of negative matter were placed next to a sphere of positive
matter of equal magnitude, then both spheres will move off in the same
have two objects, one made of negative matter and one made of positive
matter. The negative-matter object will create a repulsive
gravitational field at the position of the positive-matter object. The
positive object then responds to that repulsive gravitational field by
producing a gravitational force in the direction away from the negative
object. The positive mass then accelerates in the same direction as the
applied force — away from the negative mass.
In a similar manner, the positive object creates an attractive
gravitational field toward the positive mass. The negative object
responds to the gravitational field by producing a force in the
negative direction — away from the positive object. The force applied
to the negative object produces an acceleration. The acceleration,
however, is towards the positive object, because the applied force was
away from the positive object and the negative mass acts perversely to
the applied force. We thus have the expected but paradoxical result
that both the positive and negative masses move off in the same
direction at a constantly increasing velocity." (Robert Forward: The
Power of Negative Matter, Page 37 in New Scientist, 17 March 1990)
strange behaviour appears to violate the conservation of momentum.
However, if the masses are equal and of opposite value, the momentum of
the system will be zero if they both travel and accelerate together,
regardless of speed.
antigravity engine would have to flatten the curvature of space in
order to neutralize Earth's gravitational field. However, the
reengineering of the space-time continuum is clearly beyond our current
technology, and will no doubt remain so for the foreseeable future.
other hand, if
negative matter is more than a mathematical fiction, and substantial
quantities exist in close proximity to Earth, then it may just be
possible to construct something like an antigravity engine. However, if
it is nothing more than a hypothetical concept (and I think it may be
just this) then antigravity, like perpetual motion, will be forever
beyond our reach.
Forward, R. The Power of
Negative Matter, New Scientist, 17th March 1990
Nicholls, P. The Science
in Science Fiction, Michael Joseph Ltd., London, 1982
Park, R. Voodoo Science,
Oxford University Press, New York, 2000
Rothman, M. Pseudoscience
on the Internet