202
PHVSICS OF THE IMPOSSIBLE
Similarly, if we have a pair of scissors, the point at which the
blades cross each other moves faster the farther you are from the joining point. If we imagine scissors that are a light-year long, then by closing the blades the crossing point can travel faster than light. (Again,
this is not important since the crossing point carries no energy or information.)
Likewise, as I mentioned in Chapter Four, the EPR experiment enables one to send information at speeds faster than the speed of light.
(In this experiment, we recall, two electrons are vibrating in unison
and then are sent speeding in opposite directions. Because these electrons are coherent, information can be sent between them at speeds
faster than the speed of light, but this information is random and hence
is useless. EPR machines, hence, cannot be used to send probes to the
distant stars.)
To a physicist, the most important loophole came from Einstein
himself, who created the general theory of relativity in 1915, a theory
that is more powerful than the special theory of relativity. The seeds of
general relativity were planted when Einstein considered a children's
merry-go-round. As we saw earlier, objects shrink as they approach
the speed of light. The faster you move, the more you are squeezed. But
in a spinning disk, the outer circumference moves faster than the center. (The center, in fact, is almost stationary.) This means that a ruler
stick placed on the rim must shrink, while a ruler placed at the center
remains nearly the same, so the surface of the merry-go-round is no
longer flat, but is curved. Thus acceleration has the effect of curving
space and time on the merry-go-round.
In the general theory of relativity, space-time is a fabric that can
stretch and shrink. Under certain circumstances the fabric may stretch
faster than the speed of light. Think of the big bang, for example, when
the universe was born in a cosmic explosion 13.7 billion years ago.
One can calculate that the universe originally expanded faster than the
speed of light. (This action does not violate special relativity, since it
was empty space-the space between stars-that was expanding, not the
stars themselves. Expanding space does not carry any information.)
PHVSICS OF THE IMPOSSIBLE
Similarly, if we have a pair of scissors, the point at which the
blades cross each other moves faster the farther you are from the joining point. If we imagine scissors that are a light-year long, then by closing the blades the crossing point can travel faster than light. (Again,
this is not important since the crossing point carries no energy or information.)
Likewise, as I mentioned in Chapter Four, the EPR experiment enables one to send information at speeds faster than the speed of light.
(In this experiment, we recall, two electrons are vibrating in unison
and then are sent speeding in opposite directions. Because these electrons are coherent, information can be sent between them at speeds
faster than the speed of light, but this information is random and hence
is useless. EPR machines, hence, cannot be used to send probes to the
distant stars.)
To a physicist, the most important loophole came from Einstein
himself, who created the general theory of relativity in 1915, a theory
that is more powerful than the special theory of relativity. The seeds of
general relativity were planted when Einstein considered a children's
merry-go-round. As we saw earlier, objects shrink as they approach
the speed of light. The faster you move, the more you are squeezed. But
in a spinning disk, the outer circumference moves faster than the center. (The center, in fact, is almost stationary.) This means that a ruler
stick placed on the rim must shrink, while a ruler placed at the center
remains nearly the same, so the surface of the merry-go-round is no
longer flat, but is curved. Thus acceleration has the effect of curving
space and time on the merry-go-round.
In the general theory of relativity, space-time is a fabric that can
stretch and shrink. Under certain circumstances the fabric may stretch
faster than the speed of light. Think of the big bang, for example, when
the universe was born in a cosmic explosion 13.7 billion years ago.
One can calculate that the universe originally expanded faster than the
speed of light. (This action does not violate special relativity, since it
was empty space-the space between stars-that was expanding, not the
stars themselves. Expanding space does not carry any information.)