論文の公開元へBehavior of Chameleon Mechanism on F(R) Gravity
概要
The equations of motion devised by Newton in the 17th century allowed the motion of objects
to be treated mathematically. In Newtonian mechanics, force was understood as a remote action
acting instantaneously on distant points of matter. In contrast, electromagnetic mechanics,
invented by Maxwell in the 19th century, introduced a field called electromagnetic field to mediate
the force. In this theory, an object such as a magnet generates a magnetic field, and this field
acts on a distant substance to transmit force. This concept is called proximity action as opposed
to distance action. With the birth of electromagnetism, it was discovered that light is a wave
that propagates through an electromagnetic field. This electromagnetic field was thought to be
transmitted through an unknown substance called the ether. According to this conventional idea,
the speed of light changes depending on the relative speed of the inertial system and the ether.
However, actual observation and experiments have shown that the speed of light does not depend
on the inertial system. Einstein’s special theory of relativity showed that there is no such thing as
an absolutely stationary system in time and space, but rather that they are relative to each other
and vary depending on the observer. This discovery led to a unified understanding of Newtonian
mechanics and Maxwell’s electrodynamics. In addition, Einstein developed the general theory of
relativity to describe curved space. With this theory, he succeeded in calculating the movement
of the perihelion of comets, which had been impossible to calculate with Newtonian mechanics.
Despite the success of general relativity, there are still unsolved problems. Three typical
examples are Dark Energy (DE), inflation, and Dark Matter (DM). When the general theory of
relativity was first completed, Einstein thought that the solution that the universe is expanding
was unnatural. Therefore, he added a cosmological constant term to the Einstein equation to
cancel out the expansion. However, Hubble’s observation of the redshift of galaxies revealed that
the distance between two galaxies increases the relative velocity of their separation from each
other. This fact led to the discovery that the universe is expanding at an accelerating rate. To
explain this accelerated expansion, we need an unknown energy (DE) whose density does not
diminish with the expansion of the universe, and the cosmological constant added by Einstein
corresponds to this DE. The cosmological constant written by Einstein is equivalent to this DE.
There are various possible origins of this DE. For example, in quantum field theory, the vacuum
has a constant energy. However, this energy has the Planck scale Mpl ∼ O(1038 )GeV 2 , which is
123 orders of magnitude higher than the DE energy scale Λ ∼ O(1085 )GeV 2 . Therefore, theories
to explain this hierarchy and the effects that produce DE are currently being studied.
The second unsolved problem is the inflationary universe, which was the subject of the Big
Bang theory proposed by G. Gamow in 1928, which states that the universe began as a ball of
fire. In 1928, G. Gamow proposed the big bang theory that the universe began as a ball of fire.
However, this theory raised the problems of flatness, in which the present universe is extremely
flat, the horizon problem, in which there are correlations in regions of space that cannot be
causally related, and the monopole problem, which has been predicted by the grand unified
theory but has not yet been found [1, 2]. The inflationary universe was devised as a solution
to these problems. In this theory, the universe expands rapidly at the beginning, and then the
expansion energy is instantaneously dissipated into heat energy to produce particles. However,
general relativity cannot induce the inflation that is said to have occurred at the beginning of
the universe. ...
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