Time and Vector
Well i've heard that we are travelling forward in time
at a certain rate.
If this is true, then does that mean that time is a vector quantity
since we are travelling at a speed in a direction (forward)?
I so how does that tie in with the fact that particles that travel at
the speed of light experience no time?
Are they travelling at the speed of time
but in the opposite direction? Does this even make any sense?
According to the Physics Texts that I have used, Time is a scalar
quantity -- it is not defined as having a direction. But I think your line
of reasoning is very perceptive! You might want to pose this question to a
PhD in Physics; try a local university and call their Physics department.
To understand things moving close to, or at, the speed of light, Einstein's
Theory of Special Relativity is required. Einstein invented the idea of
space-time: thinking about time as just another dimension. What makes it
hard to imagine is the fact that we can't "see" it. Someone who lives in a
two-dimensional existence, perhaps a spot on a piece of paper, could never
move up from the paper, probably could not even imagine the dimension
perpendicular to the paper as even existing. Erase the dot, and as far as
other dots are concerned it has disappeared. This is how the time dimension
is imagined to relate to us. It is there, but we cannot see it. We move
along the time dimension, but our senses can only experience one point (what
we call "now").
As for traveling through time, relativity is based on perception. Both
spatial length (distance) and time length between events can appear
different to different observers, depending on how fast the observers are
moving with respect to each other. So long as speeds are not near the speed
of light, everything works the same for everybody. If an observer sees you
as moving close to the speed of light, and you in turn see the observer as
moving close to the speed of light, effects of relativity start to matter.
The time between events and the distance between events as you see things
can appear different from how the other observer sees things. Passage of
time as a very fast particle sees it is different from how you see it.
There are particles that, when still, appear to exist for less than one
second before decaying into smaller particles. When these particles move
close to the speed of light, they can live long enough to get here from
other stars. According to Einstein's theory, the particle sees things as a
fast moving solar system moving to it. The particle sees the distance
traveled by the solar system, as well as the time for the journey, to be
much smaller than we see it. For the particle, the time of the journey was
half of a second. For us, it was several years. Each is correct in its own
frame of reference.
As objects, even objects as big as galaxies, travel toward or away from you,
they appear to become flattened. The width stays constant, but distance
from front to back appears to shrink.
This is not noticed until the object is moving close to the speed of light.
As the speed approaches the speed of light, such distances (and
corresponding time durations) approach zero. How a speed of light particle
truly experiences time can not be known for sure, but it appears that at the
speed of light, everything is in one position and everything happens at one
time. Distance and time cannot be percepted at the speed of light.
This in turn supports the theory that no object can be accelerated to the
speed of light: it would require infinite force and infinite energy.
Likewise, no speed-of-light object can be slowed down. It can be delayed
for short spurts of time, but not actually made to travel slowly.
Click here to return to the Physics Archives
Update: June 2012