Lesson 43 Velocity and Time

If one uses a loop of wire and a galvanometer a light will move when an electric current passes through the wire. This electric current can be created by moving and removing a bar magnet from the loop of wire. The force that sets electric charges in a wire in to motion are described by the equation below:

F = qE + qv x B

Einstein desired to further explain why this equation remains true and developed the Theory of Relativity and found that time is relative:

delta(t) = gamma delta (t)o

gamma = 1/sqrt(t - v^2/c^2)

According to the Theory of Relativity, timed events occur more slowly by a factor of gamma, depending on the position of the observer. The Theory of Relativity is a theory of motion based upon different observers where there is no absolute motion and no absolute rest.

Nothing travels faster than the speed of light. If an observer is detecting the speed of a baseball thrown from a moving platform the speed or velocity cn be determined by the slope of the observer and baseball in the space-time continuum where both space and time are independent axes.

v' = delta(x)'/delta(t)'

Speeds computed in the spacetime frame are always less than one, or the speed of light.

Ux = (U'x + v)/(1+ VU'x/c^2)

Even along the direction of relative motion, components of velocity never add to a speed greater than the speed of light.

Uy = U'y/(gamma(1 + VU'x/c^2))

Uz = U'z/(gamma(1 + VU'x/c^2))

The veocity transformation does affect components perpendicular to the motion because although distances remain the same, time changes from one frame to the next.

There is a test of relativity in the phenomenon decay of cosmic ray muons.

Because time is relative, if one travels close to the speed of light to an area of space ten lightyears away, due to Lorentz contractions, the individual travelling only ages several months. An individual on earth ages 20 years.

In a completely empty universe time and space have no relevance. In a universe with many bodies, no object is at complete rest, but remains in motion until an object acts upon it, following the law of inertia. Time and space are relevant in this universe. Rest can only be observed in frames of time and space.