Speed of
light may have changed over time
Recent results (New Scientist, American
Institute of Physics,…,) have indicated that fine structure constant may not be
a constant, meaning that speed of light may not be a constant also
and may have changed over time !
The fine-structure constant, α (dimensionless number,
α = e2/4πε0hc = 1/137.03599) is the
ratio of the quantum unit of electromagnetic
force to the electron-based quantum unit of inertial force. This number determines
the strength of the electromagnetic force. More accurately, it governs how
strongly a charged particle will interact with that force (i.e. absorb or emit
photons).
The size of alpha determines how
well atoms hold together and what types of light atoms will emit when heated
up. And just as the elastic band keeping a swimsuit snug will gradually relax
with time, so it is reasonable to ask whether an atoms' elasticity (or alpha)
might also vary with time.
The idea that the constants might
evolve over time is an old one. Paul Dirac first took these constants and
combined them together to form dimensionless numbers. One example is the
magnitude of the ratio of the universe's age and the time it takes light to
travel across an electron, is very similar to the magnitude of the
electrostatic and gravitational forces present in the hydrogen atom. (1040
compared to 1039) As the universe has of course got older, to keep
this relationship constant, the values of the fundamental forces would have to
change over time.
A recent investigations of numerous
group of scientists test this proposition by sampling ancient light emitted by
ancient atoms, and comparing them to modern light from modern atoms. In
particular they looked at the relative spacing of doublets of absorption lines
in the spectra of several types of atoms in distant gas clouds lying in front
of still more distant quasars. The fine-structure constant is so called because
it is related to the fine-structure apparent in atomic spectra. These spectral
lines are due to the transitions of electrons between available energy levels.
This is one of the primary physical constants that determines
the nature of the Universe. If it were a different value, electrons wouldn't
orbit atomic nuclei in quite the same way, if at all.
If it were
larger, you wouldn't be able to tell the difference between matter and
radiation.
If it were
smaller, particles might as well ignore the electromagnetic interaction.
Another reason having the fine-structure constant change
over time is that it allows one to postulate the speed of light might not be
constant. This would explain the flatness, horizon and monopole problems in
cosmology.
Recent work has shown the universe is expanding at an ever
faster rate, and there may well be a non-zero cosmological constant after all.
(Einstein said his inclusion of the constant to balance the books was his
"worst mistake".) There is a lot of theories where the speed of light
is determined by a scalar field (the force making the cosmos expand, the
cosmological constant) that couples to the gravitional effect of pressure.
Changes in the speed of light convert the energy density of this field into
energy. The basic upshot being when the universe was very young and hot during
the radiation epoch, this prevented the scalar field dominating the universe,
as the universe expands pressureless matter dominates, variations in c
decrease (and therefore alpha becomes fixed and stable) and the scalar
field begins to dominate, driving a faster expansion of the universe.
Well,
the jury is still out on this one, there is quite simply not
enough evidence to prove the fine-structure or any other fundamental constant
changes with time.
If the constants can be proven to change however,
it could possibly validate new theories of physics, and help confirm other
hypothesis such as the existence of dark energy and quintessence; scalar fields
involved in a varying cosmological constant.
Scientific American recently published an
article that suggests that perhaps the fine structure constant isn't, in fact,
constant. More specifically, astronomers have found observational evidence that
seems to indicate that the fine structure constant
was weaker by one part in a thousand around 5 billion years ago. One the one hand, this seems almost irrelevant. A difference of one part in a
thousand, 5 billion years ago, doesn't affect us directly in any way. On the
other hand, it makes all the difference; if one of the so-called
constants of the Universe is changing, this
pokes holes in all sorts of current theories in physics.
Anyhow, fact that fine structure constant was
weaker in the past imply that light velocity (c = e2/4πε0hα)
should have (with same: e, π, ε0 and h) a larger value !!!
Current experimental value for light velicity is
cexp= 299792458 m/s and “one part in a thousand” difference is
299792458/1000 = 299792,458 m/s. Considering that fact we obtain:
299792458 m/s + 299792,458 m/s = 300092250.458
m/s
what is very, very close to ours “Maxwell’s
EMW theoretical value” !!! Moreover, basic matter–radiation relationship
“mechanism” is very close to our suppositions !
If You have any comment you can email me immediately or send me Your oppinion later on: gmarjanovic@beotel.rs