Relativity 2: General Theory of Relativity
The general theory of relativity
The theory that changed all basic concepts of thinking with regard to the Universe when it was published by Einstein in 1916. It is a mathematical resolution for many bizarre effects which occur in the Universe, for which Newton's Laws give no solution, and shows that gravity is a property of space and not just a force between two bodies.
It explains that time is not a constant factor, but will be dilated not only when traveling at high velocities, such as the speed of light, but also in area's of large gravity.
The theory is a complex of mathematics that calculate the relation between the three dimensions of space and the dimension of time, the time space.
Resting mass is equal to
inertial mass
To change a body's velocity a force must be acting on it (Newton's
Laws). The required force is proportional to its resistance against
changes in velocity : the inertial mass of the object,
massive objects require larger forces, and lighter objects smaller.
The strength of gravitational force between two objects is proportional
to the product of their rest mass (the quantity of matter).
The special theory of relativity assumes
that the speed of light is equal to all observers, even if these observers
are changing in speed. This results in the equality of gravity and acceleration.
Most of the time this is explained with an example of an elevator.
When a person who stands in an enclosed elevator suddenly feels himself
getting heavy, he will not be able to tell the cause of this.
The lift could suddenly be pulled-up (inertial mass), or additional mass
may have appeared below the elevator, which increased the force of gravity
(rest mass).
In both cases the person would feel the same downward pull of gravity.
Einstein asserted that these effects are actually the same, which means
that gravity and acceleration are the same.
Space
is curved.
With his special relativity theory Einstein showed that in accelerated
environments the space is curved and times is dilated.
In his general theory of relativity he explains that acceleration
and gravity are equal, this implies that also gravity
will curve space and dilate time, just like acceleration does. The greater the forces of gravity the more space will be curved and time
dilated.
Newton already showed that gravity is a property of mass,
the more mass, the greater the forces of gravity. In other words it is
mass that curves space and dilates time.
A conclusion of the general theory of relativity is that distances
in space are influenced by mass. Due to mass the space is curved, these
curves prolong the distances between objects and so the traveling time
between two objects increases.
The greater the mass the greater the curvature, the longer the traveling
time will be.
This could be imagined by means of a large elastic surface, for example a sheet of
rubber. This is the 'empty time space' as Einstein called it.
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Hold the mouse over the image to see the marble roll. |
Now if we place a heavy sphere in the center of the rubber sheet, the
sheet will become curved, this is the deformation of space by heavy mass.
When a small marble rolls over the sheet, it will roll in a linear direction, however when it rolls along the massive sphere, then the marble will follow the way of the deformation in the sheet made by the sphere. That is the 'force of gravity' according to the theory of relativity. |
Due to the curved sheet, it takes longer for the marble to cross the sheet than when the large sphere was not there. Thus the traveling time is influenced by the mass. The equations of relativity predict that gravity, or the curvature of space time by matter, not only stretches or shrinks distances, but also will appear to slow down or "dilate" the flow of time.
Long before they were actually observed, the theory predicted the existence of black holes.