Special Relativity

What is a frame of reference?

a coordinate system that defines the location of the observer

What is an inertial frame of reference?

any frame of reference that moves at a constant velocity

what are the two postulates of relativity?

1. the laws of physics are all the same in all inertial frames of reference

2. the speed of light remains constant at “c” in all inertial frames of reference

what is simultaneity?

simultaneity refers to the occurrence of two events at the same time in a given frame of reference

why can no object travel the speed of light in a vacuum?

as an object approaches the speed of light, its Lorentz factor approaches infinity. this means it will require infinite momentum, thus infinite energy to travel at the speed of light, which is not physically possible. thus no object with mass can travel at the speed of light.

why can photons travel at the speed of light.

they have zero rest mass allowing them to travel at the speed of light.

what is time dilation?

the difference in elapsed time between observers moving relative to each other

what is proper time interval?

the time interval measured in the frame of reference in which the object is at rest

what is relativistic time interval?

the time interval measured in a moving frame of reference

what is length contraction?

the length of an object moving at high speed appears shorter along the direction of motion to a stationary observer.

what is proper length

the length measured in a reference frame where the object is at rest

what is relativistic length?

relativistic length of an object is the length measured by an observer who sees the object moving relative to their frame of reference.

what is rest mass?

the mass of the object, measured in a frame of reference where the object is at rest

what is relativistic momentum?

the momentum of an object traveling close to the speed of light