Life on Earth Without the Theories of Relativity

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Life on Earth Without the Theories of Relativity

• How would our lives be different on Earth if we
  did not have any knowledge of the theory of
  relativity?

Meagan Thiedemann Physics 11A
Mr. Jennings December 9, 2005
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Overview
In 1905, Einstein published a paper that became
known as the special theory of relativity. Other
than this theory, there is the general theory of
relativity. The special theory of relativity is
special because it applies the principle of
relativity to a special case of inertial
reference frames in flat spacetime. The effects
of gravity are ignored in flat spacetime. This
theory of special relativity says that there is
no set frame of reference, but that physics has
to look the same to all observers who are
travelling at a constant velocity. The equation
Emc2 is also explained in the special theory of
relativity, and is the only equation in which
mass can change. Mass is a magnitude that is
dependant on the amount of energy. The general
theory explains how the special theory and
Newtons law of universal gravitation tie in with
the fact that gravitation is not due to a force,
but a manifestation of curved space and time,
which is produced by the mass-energy content of
spacetime. Spacetime is treated as a 4-d
Lorentzian manifold that is curved because there
is mass, energy, and momentum within it. What is
seen on Earth as the force of gravity, is
described in the general theory as continuous
physical acceleration caused by the mechanical
resistance of the surface of Earth.
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Without These Theories

• Understanding of Gravity
• Space shuttles, and Satellites in orbit
• Perception of Straight and Curved Lines in Space
  Travel

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Understanding of Gravity
Our understanding of Gravity may have been very
different today if the theories of relativity had
never been produced. It is quite possible that
scientists may not know why it is that a block of
wood half the size of another falls at the same
rate. Because the theory of general relativity
states that it is continuous physical
acceleration caused by Earths mechanical
resistance that makes things fall at the same
rate as one another, we may not understand why it
is that an object that is clearly heavier than
another falls at the same rate as it. In this
sense, our understanding of why gravity works the
way it does would be very different.
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Space Shuttles, and Satellites in Orbit
There would be effects on the people in space
shuttles that we would not be able to explain if
it werent for these theories. The special
theory states that the closer an object travels
to the speed of light for prolonged periods of
time, the time will actually be slower for them
than it is for people on Earth. This means that
the astronauts traveling on space shuttles would
actually age a bit slower than the rest of the
population on Earth. We would not understand why
this happens without the theories of
relativity. Satellites in orbit would be
difficult to explain as well without the theories
of relativity. We may not understand why it is
that these satellites can be suspended in space,
and travel around the Earth at very high speeds.
The equation Emc2 can be derived to E/mc2.
This means that if the energy of these satellites
goes up, the mass will go up as well. This makes
the satellites seem heavier when they are in
space, allowing them to stay in orbit, although
they will never reach the speed of light (c).
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Perception of Straight and Curved lines in Space
Travel
What our mind translates as a curved line in
space, for example if we see something flying
through space, is actually a straight line. It
is difficult for our minds to see that there are
actually 4 dimensions in space, the fourth
dimension being time. Our minds have a much
easier time picturing space as flat, much like a
map of the Earth that is drawn out. Because of
this, we see straight lines as being curved.
Whatever it is that we see flying is actually
going straight, from one destination to another,
and is in fact not making an arc. Einsteins
theory explains that the curvature of spacetime
is caused by the presence of stress-energy. This
is when there is an object with a very large
mass, in this case the Earth, that is causing the
local spacetime geometry to produce a curve. The
larger this object is, the more curvature there
will be. This causes everything to accelerate
towards the object causing the curvature. So
objects that are accelerating towards Earth
against this curvature, which almost seems like a
dent look like the are creating a curved line
in their travel, when they are in fact moving
straight.
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It Goes Unnoticed
The theories of Relativity are something that we
dont pay much attention to in our daily lives.
It is something that is simply there, and it is
difficult to imagine what would be different
about life without it. These theories have
become a part of our lives in many ways, and have
maybe influenced many people in many ways. The
theories of relativity are not something that we
can simply ignore, but they are also not
something that everyone must know everything
about. We, as people, do not notice the effects
of the Theories of Relativity until we stop to
actually think about it.
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The End