Time required to do what? To move from one place to another, divide the distance by the speed of light.
Electrons are able to travel close to speed of light.
Nobody knows for sure. We have never witnessed a physical object traveling faster than the speed of light.
When you (or an object) travel without changing speed, then you have constant velocity (speed). This means there is no change in speed (acceleration) when you (or an object) is traveling.
a car traveling the speed limit
No, speed is directionless.
The speed of light is constant. It is 671,000,000 mph.
That depends on the speed of the spaceship. If it were traveling at the speed of light, which is the maximum speed that any object can reach, it would take 640 years to get there.
An object that normally doesn't move at light speed (so, this doesn't include photons for example) CANNOT move at the speed of light. As it approaches the speed of light, its mass will get higher and higher (and tend towards infinity); as will the energy required to continue speeding it up.
subsonic
It is not possible for any physical object to accelerated to the speed of light. But in one particular extreme it is possible to slow the speed of light according to the Bose-Einstein Condensate. The question better stated would be "Would an independent observer see light emanating from a source that is traveling backwards at the speed of light?" Yes. Light always travels at the same rate. No matter how fast you are traveling, any light that you emit will always travel at a constant rate. (note that it's not possible for a physical object to actually travel at the speed of light in a vacuum).
No. Speed of light is constant in all frames of reference, even if you are also traveling at the speed of light, the photon will speed away from you at the speed of light. When you see an object, what is happening is that photons are reflected off the object you are looking at and bounce back into your eye. However, if you are traveling faster than the speed of light, the photons can never reach you to start with, hence, you are invisible until your speed decreases to something below the speed of light. It is possible to travel faster than light in many ways. First, if you have a negative amount of energy, you will always travel faster than a speed of light. Another possible way is to compress the space in front of you, then move to your destination before re-expanding the space you have just past.
there's four speed. There are constant speed, average speed, increasing speed, and decreasing speed. choose one of them