subspace
- (MATH) A subset A of
a topological space X
with the inherited topology: the open set in A consists of the
intersections of the open sets of X with A.
TOPOLOGY
MATHEMATICS
- (SF) In the Star
Trek universe, a domain outside of the normal spacetime
continuum through which communication signals and data streams are able
to travel faster than the speed of light (see FTL
travel). In ST jargon, a subspace fracture is a
rupture or tear in the subspace continuum that allows subspace to enter
normal space.
Something akin to subspace or faster-than-light communication might
be possible if a theory reported by Fabrice Petit of the Belgian Ceramic
Research Centre and Michael Sarrazin of the Facultés Universitaires
Notre-Dame de la Paix, in Belgium, in September 2007 in the journal
Physical Review D, proves to be true. These researchers describe
what amount to shortcuts through extra dimensions.
Petit and Sarrazin, inspired by string
theory, describe a situation in which the universe we know is actually
just one sheet or brane in a higher dimensional
spacetime. In this model of reality, our universe includes a second
sheet that we're not normally aware of because we're confined to our
own sheet. Petit and Sarrazin describe a specific "braneworld" scenario
in which there are just these two branes. In this case, although particles
can't exist between branes, they can travel back and forth between the
sheets by way of quantum mechanical tunneling,
which allows passage across barriers that classical physics considers
insurmountable. Under the right circumstances, a powerful magnetic
field can cause a particle to oscillate between the two branes.
If the other brane is warped in a certain way, distances there may be
shorter than in our own brane. This means if a fast-moving particle
were made to travel in the other brane for a while before returning
to ours, it could actually get to a distant part of our universe much
faster than a light signal confined to our brane.
Petit and Sarrazin point out that their theory only works for fermions
– particles that include protons and neutrons, but not all types of
atoms. Since our bodies contain a lot of atoms that are not fermions,
humans could never take such shortcuts. But by making electrons or other
fermionic particles take shortcuts through the other brane, it might
be possible to communicate faster than light speed, just like in Star
Trek. Breaking the light speed barrier is normally thought to be impossible
because it allows particles to time
travel, leading to problems with causality
– paradoxes that spring up when effects can happen before their
causes. The Petit-Sarrazin scenario needn't violate causality because
the shortcutting particles get to their destination faster than light
only when confined to our brane. When their path through the extra dimension
is taken into account, they actually obey an overall speed limit, allowing
causality to be preserved.
SCIENCE
OF STAR TREK
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