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**These are excerpts and elaborations from my book "The Nature of Consciousness"**

The Special
Theory of Relativity was born ("On the Electrodynamics of Moving
Bodies", 1905) out of Albert Einstein’s belief that the laws of nature
must be uniform, whether they describe the motion of bodies or the motion of
electrons. Therefore, Newton’s equations for the dynamics of
bodies and Maxwell’s equations for
the dynamics of electromagnetic waves had to be unified in one set of
equations. In addition, they must be the same in all frames of reference that
are "inertial", i.e. whose relative speed is constant. Galileo had shown this to be true for Newton's mechanics, and Einstein
wanted it to be true for Maxwell's electromagnetism as well. In order to do
that, one must modify Newton’s equations, as the Dutch physicist Hendrik
Lorentz had already pointed out in 1892. The
implications of this unification are momentous. Relativity
conceives all motion as "relative" to something. Newton's absolute motion, as the
Moravian physicist Ernst Mach had pointed out over and over, is an oxymoron. Motion is always
measured relative to something. Best case, one can single out a privileged
frame of reference by using the stars as a meta-frame of reference. But even
this privileged frame of reference (the "inertial" one) is still
measured relative to something, i.e. to the stars. There is no frame of
reference that is at rest, there is no "absolute" frame of reference.
While this is what gave Relativity its name, much more "relativity"
was hidden in the theory. In Relativity,
space and time are simply different dimensions of the same space-time
continuum, as shown by the Russian mathematician Hermann Minkowski ("The
Basic Equations for Electromagnetic Processes in Moving Bodies", 1908). Einstein showed that the length of
an object and the duration of an event are relative to the observer. This is
equivalent to calculating a trajectory in a four-dimensional spacetime that is
absolute. The spacetime is the same for all reference frames and what changes
is the component of time and space that is visible from your perspective. One person’s
time is another person’s mixture of time and space. All quantities
are redefined in space-time and must have four dimensions. For example, energy
is no longer a simple (mono-dimensional) value, and momentum is no longer a
three-dimensional quantity: energy and momentum are one space-time quantity
which has four dimensions. Which part of this quantity is energy and which part
is momentum depends on the observer: different observers see different things
depending on their state of motion, because, based on their state of motion, a
four-dimensional quantity gets divided in different ways into an energy
component and a momentum component. All quantities are decomposed into a time
component and a space component, but how that occurs depends on the observer’s
state of motion. This phenomenon
is similar to looking at a building from one perspective or another: what we
perceive as depth, width or height, depends on where we are looking from. An
observer situated somewhere else will have a different perspective and will
measure different depth, width and height. The same idea holds in space-time,
except that now time is also one of the quantities that changes with
“perspective” and the motion of the observer (rather than her position)
determines what the “perspective” is. This accounts for bizarre distortions of
space and time: as speed increases, lengths contract and time slows down (the
first to propose that lengths must contract was, in 1889, the Irish physicist
George Fitzgerald, but he was thinking of a
physical contraction of the object, and Lorentz endorsed it because it gave
Maxwell's equations a
particularly elegant form, whether the observer was at rest or in motion). This
phenomenon is negligible at slow speeds, but becomes very visible at speeds
close to the speed of light. An observer who
travels away from a clock-tower at the speed of light, would always observe the
same time, as if the clock's hands never moved and time was still. If the
observer traveled at a speed slightly less than the speed of light, the
observer would see the hands of the clock moving very slowly over the years as
the light would take a long time to travel that distance. On the other hand an
observer who travels very slowly away from the same clock-tower (all of us on
human-made vehicles), would observe the clock's hands moving. Therefore time
depends on the speed of the observer relative to the clock (or viceversa). A
moment of time is slower at higher speed. Time intervals are dilated by higher
speeds. A further
implication is that "now" becomes a meaningless concept: one
observer's "now" is not another observer's "now". Two
events may be simultaneous for one observer, while they may occur at different
times for another observer: again, their perspective in space-time determines
what they see. The traditional law of causality is an illusion. Two events that
follow each other from an observer's point of view may be simultaneous from the
point of view of another observer who is moving at a different speed. The
present is a concept that depends on the observer. Each observer has a
different set of contemporary events that constitute its present. Even the very
concept of the flow of time is questionable. There appears to be a fixed
space-time, and the past determines the future. Actually, there seems to be no
difference between past and future: again, it is just a matter of perspective. Time and space
complement each other: as one dilates, the other contracts. The traditional law
of causality had ceased to exist, but a new sort of causality was introduced
because any warping of space corresponded to a warping of time. The speed of
light is the same in every frame of reference. What changes in each frame of
reference is the very notion of distance and duration. That's why the speed of
light remains the same regardless of what the frame of reference is doing: what
it is doing alters its space and time in such a way that the speed of light
remains the same for everybody. Mass and energy
are not exempted from "relativity". The mass and the energy of an
object increase as the object speeds up. This principle violates the
traditional principle of conservation, which held that nothing can be destroyed
or created, but Einstein proved that mass and energy can transform
into each other according to his famous formula E=mc Light has a
privileged status in Relativity Theory. The reason is that the speed of light
is always the same, no matter what. If one runs at the speed of a train, one
sees the train as standing still. On the contrary, if one could run at the
speed of light, one would still see light moving at the speed of light. Most of
Relativity's bizarre properties are actually consequences of this postulate.
Einstein had to adopt the Lorentz transformations of
coordinates, which leave the speed of light constant in all frames of
reference, regardless of the speed it is moving at, but, in order to achieve
this result, one must postulate that moving bodies contract and moving clocks
slow down by an amount that depends on their speed. If all this
sounds unrealistic, remember that according to traditional Physics the bomb
dropped on Hiroshima should have simply bounced, whereas according to Einstein’s Relativity it had to explode
and generate a lot of energy. That bomb remains the most remarkable proof of
Einstein’s Relativity. Note that most
of the equations in Einstein’s Relativity had already been derived by others
(Lorentz, Fitzgerald, Poincare) but they were merely attempts at explaining
experimental data. Einstein introduced the principle of relativity (that the
laws of physics must be the same in all inertial systems), and those equations
became natural consequences. De facto, Einstein made a metaphysical choice: he
decided that space and time are not absolute. Once the metaphysics changed, the
oddities of the experimental data went away, or, better, became the natural
consequences of a bigger oddity. Back to the beginning of the chapter "The New Physics" | Back to the index of all chapters |