##### volume **II:** Synopsis

#### Part III: Modern Physics

### page 17: Albert Einstein

(1879-1955)

At the turn of the twentieth century even the existence of atoms was moot. Einstein not only produced a new way to look at space and time, but made great contributions to the new idea that the physical world is discrete or quantized. In particular he suggested that light, even though it has wave properties, is emitted and moves as a particle, the photon. He is best known, however, for the special and general theories of relativity. Photon - Wikipedia

Einstein announced his 'new kinematics', now known as the special theory of relativity, in 1905. He was motivated by the apparent asymmetry between the classical treatment of electric and magnetic fields even though Maxwell's equations. which describe these fields, see them as symmetrical. Albert Einstein

Maxwell's equations determine the velocity of light, and Einstein found that if we are to treat electric and magnetic fields symmetrically we must conclude that the velocity of light is independent of the velocity of the both the source of light and the observer of that light. Classical physicists like Maxwell imagined light waves travelling in a medium called the ether, like sound waves in air. Maxwell's equations - Wikipedia

This idea led to an attempt by the physicists Michelson and Morley to measure the velocity of the Earth through the ether by measuring the differences in the velocity of light coming from different directions. Despite the high precision of their measurements, they found that the velocity of light was the same in every direction. Einstein's conclusion was consistent with this result and suggested that the ether did not exist. Michelson and Morley

The special theory of relativity reveals that ordinary space appears to have a rather extraordinary structure. This structure arises from the fact that the finite velocity of any physical signal delays communication between different points in space. How an observer sees an event depends on the velocity of the event relative to the observer. Metric space - Wikipedia

Special relativity predicts that time appears to go more slowly, distances appear shorter and masses greater in a relatively moving event. Because of the great velocity of light, these phenomena are very small at the velocity differences we ordinarily experience but they become important at velocity differences typical of observations in astronomy and particle physics. Special relativity - Wikipedia

The special theory of relativity shown how to transform observations on a moving system to the rest frame of the observer. These 'Lorentz transformations' are based on the well verified assumption that all observers seen the same physical phenomena in their own rest frame. Lorentz transformation - Wikipedia

Another effect of the finite velocity of communication is the 'relativity of simultaneity'. Two events separated in space may appear to be simultaneous to one observer, but not to another, depending on the relative velocities between the observes and the events in question.

Particles at rest with respect to a given observer appear to have neither kinetic energy nor momentum. Particles in relative motion, however, are seen to have momentum which varies linearly with their relative velocity and kinetic energy that varies as the square of their relative velocity. These observations are verified if and when the observer comes into collision with the moving particles. Momentum - Wikipedia, Kinetic energy - Wikipedia

If we apply the Lorentz transformations to this situation, we find that mass and energy are related by the famous equation *E = mc ^{2}*. We will examine the consequences of this relationship when we come to deal with quantum field theory. Quantum field theory, Mass-energy equivalence - Wikipedia

Newtonian physics works in a space that comprises the three dimensions of ordinary space, plus the fourth time dimension. Newtonian space and time are independent because signals are considered to move with infinite velocity yielding zero travel time. Nevertheless, distinction between space remains real in both Newtonian and Einsteinian physics. We can move in any direction in physical space, but we are restricted to one direction in time which we usually see as a movement from past to future.

The metric imposed on physical space by the finite velocity of light has an analogue in all other situations where communications take a finite time to cover a finite distance. The evolution of email to replace snail mail, for instance, changes the spacetime metric of written communication in a manner analogous to increasing the velocity of light in physics.

From the special theory, which describes the phenomena observed by systems in uniform relative motion, Einstein extrapolated to accelerated motion to arrive at the general theory of relativity. The general theory which has the capacity to represent the whole of spacetime, and so have become one of the foundations of modern cosmology. General relativity - Wikipedia, Cosmology - Wikipedia

The structure of the Universe is constrained by the time delay in communication, so we will not be surprised to find that much of the structure of the Universe is constrained by the structure of communication. One hope for this work is to use the idea that the Universe is a transfinite communication network as a tool to develop the much sought after connection between general relativity and quantum mechanics. Unified field theory - Wikipedia, Equivalence principle - Wikipedia

[revised 23 May 2013]