In this century many astronomers, cosmologists and physicists deal with
the expansion of cosmos. Einstein created a cosmological constant which
was served to describe the stability of cosmos. He didn`t know than that
the cosmos was expanded. But the astronomers told about their observations
that the cosmos was expanded he named his constant a great mistake and
canceled it. The constant was fergotten for a long time.
The newest observations served such reasons which was pop up the cosmological
constant again. These observations showed that the cosmos expanded with a
great acceleration. This is problem for the experts becouse they think
it must be a power which contradicts the gravitation and pushes the elements
of cosmos. Actually this power must overtake the gravitation (which is a
contractive power) to be able to push the elements in an accelerated speed.
There are some imagines about this power. To solve this problem they
research the first second after the big bang when the powers (gravitatin,
atomic powers, and so on) and materials (normal, radiation, dark) emerged.
Very complicated quantummechanical calculations need to solve these things.
Hence some people think the gravitation at a conditions is contracting
but at another condition is pushing. They say to must modify the cosmological
constant that it follow this statement and it may describes the acceleration
too. Others think there is such field which push the other materials
like it has negative gravitations (quintessence). Else operate the
dark material which is invisible for us but it is found everywhere consists
of vacuum. So we must consider the vacuum elseway what we think about it
this time. This dark material has energy (vacuum-energy) what pushes the
elemnts of cosmos. "Virtual" particles serve this energy when they arise
and consumate. These problems was pop up becouse the observations showed
the expansion of the cosmos. These observations based on redshift what
I`d like to deal with.

     The redshift may described in a short form in this paragraph.
In the light of incendescent gas emit spectrum lines which are found in
the lightspectrum. This spectrum may produced by a prisma or an optical
grid. These spectrum lines are specific to the chemical elements and
they are found at the corresponding place of the lightspectrum.
The astronomers can conclude the presence of a chemical element in a star
by the proper spectrum line is found in the spectrum.
I notice here that there are emission and absorption spectrum lines.
Both are able to identify the chemical elements. The spectrum held the
blue (short wavelength) to red (long wavelength) colors. There are
invisible wavelength in the spectrum too.
After this description we can understand the redshift. If the spectrum
lines offset from the expected place to the direction of red color
than we name this redshift. This happen when the source of light moves
away from the observer. We call this optical doppler-effect. This true at
the soundwaves too. In fact it was discovered at event of soundwaves.
We can observe this if we hear a sound of car which approaches to us than
moves away from us. When it approach to us we hear its sound higher and
when it moves away we hear its sound deeper. Actually its sound is betwen
the both one. The deeper sound match to the longer wavelength.
Consequently we say that a star or galaxy moves away form us when its
spectrum lines show the redshift.

     Next I describe how I explain the expansion of cosmos considered the
redshift. Instead of mathematical formation I use the graphical solution.
This is a fact that the redshift exists becouse it is measurable and
many experts measured yet. We know form the physics that a moving source
of waves couses this phenomenon which moves away form us. You can see on
the below figure how the wavelength changes by the moving source of waves
if we compare it to a standing one. We can relate the motionless or
movement to a fixed point independently that there is an observer on that
point or not becouse if we take there an observer than he will observe
the phenomenon immediately.




                                1. figure

     The circles denote the front of waves which follow each others.
A standing source of waves is shown on the left of the figure and the other
side of the figure is shown a moving source of waves. If the observer stands
on the A point he observes that the source of waves approaches to him.
But he stands on the B point he senses that the source of waves moves away
fom him becouse he observes that the wavelength longer than he expected it.
Actually he must know how long wavelength of the motionless source of waves
emits. Let us suppose that he know it form else measurements. The rapidity
of front of wave depends on the kinf of wave and medium in which the waves
move. At event on the light is (in the vacuum) nearly 300.000 km per secund.
We mark this rapidity with c. The v rapidity of source of waves may far
smaller than the c rapidity. Certainly the observer may move any direction.
In this event we must add up the both rapidity to calculate the rigth
movement. For simplicity we consider that the observer stands.
If the moving source of waves stops the observer measures the original
wavelength for the next time when it arrives him.
     
     Although the oscillation go on time, like all processes in the
physics, but this time is humanlike. But we must face up to very huge
time and distance in the astronomy. They measure the redshift by the
distant galaxies. We know this galaxies are many billions of lightyears
from us ( 1 lightyear is that distance what the light travels in 1 year).
But this distances not only distances but some billion years are back to
past. The light what we see now starts some billion years before form
that galaxy. Consequently we detect (measured the redshift) the galaxy
moved away from that point where we moved to now. But this happened in
the past so we can`t say anything about the movement persists in present
time too. I show it in the figure below.




                                2. figure

     The time-axle is horizontal and the distance-axle is vertical.
In the past the S star moved away in v rapidity from that place where
the O observer takes place now. The light which arrived to us signs the
moving away by its redshift what happened in the past. It can`t tell
anything about the two objects relative rapidity at this time.
The location of the S` star is a guess becouse it`s not sure to changed
the direction of movement of S star betwen the two situations.
I notice here that the experts can measure the distance by the brightness
of a star (magnitude), but we consider an average brightness of a galaxy
compared it the another galaxy what we know its distance, calculated that
the brightness reduces the square of distance. The gravity lenses can help
us to measure the distance too. The light which pass on a great mass
deviates by the attraction so the mass operates like a convex lens.
We can calculate the distance of source of light from the deviation which
came from the behind of mass. Anyway the distance what we measure now
shows a distance in the past. The idea is similar to the event of redshift.

     What can we tell about the expansion of cosmos then?
According to me only the cosmos expanded in past. And we can`t say
anything about the present situation. We would say something about it
in the future some billions of lightyears away.
If there was big bang what obviously coused expansion, than the redshift
verify that. If we shaw an explosion of a missile than we can shaw that
the elements of soil blow up meanwhile move away from each others and
next thouse pull down to the soil again. I think the expnasion of the cosmos
similar to that. At the bid bang happened in a spheric symmetrical explosion.
While the pushing power existed  the elements of cosmos moved away from
each others in an accelerating rapidity. But when the pushing power
stoped the gravitation became dominating what effected to the contraction.
becouse that is an attractive power. The below figure shows the process.




                                3. figure

     The two parts of the figure show the expansion and the effective power.
On the above part of the figure the vertical axle shows the expansion,
the horisontal axle shows the time. The expansional bent line descibes
a cycle of life of cosmos from the big bang to the collaption (singularity).
The bent line assimilates to a line of slanted throwing when two forces
effects too (the accelerating force and the gravitation). The coloured
stripes show the sections of expansion of cosmos. The time intervallums
are very deformed. The closer stripe to the big bang may measured in
second but for example the green stripe denotes some billions of years.
The below part of the figure are showed the effecting powers (the original
pushing power and the gravitation). Certainly else forces were than too
but I think these two powers were significant to the expansion.
We can consider that the gravitation is a stationary power becouse it
depends to the mass of cosmos. The other power induced the explosion so
it was a very great power what decreased step by step becouse the pressure
became week. That time the part of cosmos moved away from each others
in an accelerating speed. After a long time remained the gravitation what
wanted to contract the cosmos. The green section shows an average stability.
The cosmological constant suits to that section, supposed that there is
a power which is contradict to the gravitation. The galaxies and its stars
may emerged in the third section so we see such galaxy which was in that
section than we observe an acceleration. But we may see a closer galaxy what
is closer to us in time too than we measure a plain rapidity, supposed that
we are after that section now. We can`t tell it becouse we don`t know
exactly how long a section and what section we are now. If we are in the
end of accelerating section than we measure to the galaxies move from
each others in an accelerating speed. But for example if we are the green
section we can see accelerating speed (if we see back in time enough far
from now) and plain speed (if we see back in time closer to now).
This idea follows the Hubble-law which states if the distant of a galaxy
is longer then its rapidity is greater. Certainly is right becouse if a
galaxy is further away from us we see it closer to the big bang so its
rapidity must visibly greater. If we are in the last section than we can
see so galaxies what approach to us. (No observed such phenomenon so maybe
we are in the green section). At the T time the size of cosmos approaches
to zero. The mass of cosmos is closed in space-time (singularity) and it
will remain in this statement for ever or a newer big bang will come again.

     In conclusion I compose my idea about the redshift.
The redshift what we measure now hints to a process which happened in past.
There was such section of the past when pushing power effected. That
reasoned to expand of the cosmos in an accelerating speed. There was such
section of the past when the accelerating power stoped. After that the
gravitation effected to the parts of cosmos only. For a time, while the
moving energy of the part of cosmos was so great that thouse overtake
the gravitation, the expansion continued. But after that the gravitation
won and the process became contraction. If now the astronomers measure
that a galaxy moves away from us in an accelerating speed than he likely
see back in time so far when the accelerating powers effected yet.
We don`t know what section we are now, maybe we are in the contractive
section or maybe not. The cosmological constant by Einstein denoted the
stationary statement of the cosmos. If it true than maybe wosn`t a big bang.
The world was such statement like now from the origin of time and it will
remain the present statement for ever, apart from the inside processes.
But there is the redshift what hints to an explosion and there are the black
holes (see it at the Black hole) what contradict the cosmological constant.
So that idea remained that there was a big bang. Obviously the cosmos
expanded in the past and likely expands now too, but we could say about it
really true if we would take a time-travelling to the future to see back
to the present time.

Nagy Sándor
Debrecen, May. 2001.


         
  Nasa       Homepage