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If a person in a machine traveling faster than
the speed of sound cannot hear the noise of a
sonic boom, what might a person "see" or not see
if they could (hypothetically) pass the "light
speed" barrier? What would we, on the ground, see?
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Question Date: 2002-04-15 | | Answer 1:
To be perfectly honest with you, I have no idea
what things would look like if you could go past
the speed of light. The laws of physics
essentially break down for an object moving at the
speed of light. You are basically asking the
question, "If we throw out the laws of physics (so
far as we understand it), what would the world be
like?" I'm sorry for such an unsatisfying answer,
but we can at least think about some of the basic
issues related to this idea.
Breaking the
sound barrier and breaking the light barrier are
two entirely different scenarios. While there is
no fundamental reason why traveling faster than
the speed of sound would be impossible, there is
one for breaking the light barrier. As objects
approach the speed of light, the laws of physics
(specifically Einstein's special theory of
relativity) state that the mass of that object
would also increase. As you get closer and closer
to the speed of light, the mass continues to
increase such that the mass would approach
infinity (which would, in turn, require an
infinite amount of energy to accelerate!) From the
ground, if you could watch an object approach the
speed of light, it would appear to slow down, or
ultimately (from your point of view) come to a
stop (as it came infinitely close to the speed of
light) due to the time dilation. I should also
note that there is nothing that says an object
cannot be at a velocity greater than the speed of
light, but that object would not be able to cross
the light speed barrier, meaning it could not
travel slower than the speed of light. Theoretical
physicists have predicted such particles and named
them tachyons. Does this mean that traveling
faster than the speed of light is impossible?
Perhaps not.
Einstein's special theory of
relativity applies to "flat" space-time. However,
Einstein's general theory of relativity permits
speeds above the speed of light in a curved
space-time. How can you imagine this?
As a
crude example, imagine the Earth being a giant
balloon (approximately spherical) with two people
on it - one on the north pole, and one on the
equator. Because it is so large, to each person it
appears to be flat "locally" on the surface. But
that "flat" frame of reference depends on what
part of the Earth each one is at. Now imagine that
the earth (balloon) expands. The special theory of
relativity would say that each person would still
find that nothing could break the light barrier.
However, general relativity has no restrictions
for the rate at which the Earth (balloon) can
expand. Believe it or not, there are actually
theoretical proposals out there that describe
"warp drive" or "warp bubbles" based on
this idea!
If you're interested in following up on that, try
looking for information on "Alcubierre warp
bubbles."
| | Answer 2:
As you approach the speed of light, you see the
lengths of things in front of you shrink, and
distances collapse. I imagine (don't know for
sure!!!) that if you could BE a photon, traveling
at light speed, you would lose all your individual
identity and just become a wave, and then the
concept of distance in front of you would be
meaningless. Lengths would contract down to zero
from your viewpoint, but you would cease to be an
individual particle also... at least, that is my
guess from what I know of Special
Relativity.
I have no idea what you would
see if you were traveling faster than light
yourself... it is impossible, because you would
have to have either infinite mass or zero mass. I
have heard it speculated that you would see events
running backwards in time.... I don't know if this
is theoretically sound, though.
We do see
particles that break the light speed barrier from
the laboratory reference frame however. Not for
particles traveling in a vacuum, though -only in a
medium. They emit a bluish light - similar to what
we hear when airplanes break the sound barrier.
This happens ONLY for particles traveling in a
medium like water or air, not in a vacuum, because
nothing can go faster than light in a vacuum.
HOWEVER, light SLOWS DOWN in water, which is why
rulers look bent to you when you put one in a
glass of water and observe it. Certain high-energy
particles travel faster in water than light does
IN WATER. When these particles are trapped in huge
vats of water underground,they emit a bluish light
which is called Cherenkov radiation,
read more about this after the
person who discovered it. | | Answer 3:
As far as anyone knows, it is not possible to
travel at the speed of light or to accelerate
beyond it. Science doesn't/cannot answer any
possible question, but only questions about the
physically measurable world. As your question
presupposes a state (a person traveling at the
speed of light)which cannot be observed, your
question is not answerable by the scientific
method. Does this make your question a 'bad
question'? I don't think so, many important
questions cannot be answered by Science. Can you
think of a few such questions?
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