The cosmological principle 7

 

Models of the universe consistent with the cosmological principle

Many models can be built, but here we will limit ourselves to a very simple, elementary model, although this particular model is very consistent with what is apparent from the observations. In my books I made more in-depth analysis. But that's enough for the rest of our discussion.

Here I am omitting views based models that are unacceptable to me, which I think are wrong. Among them, the LCDM (Lambda Cold Dark Matter) model is very popular today. I mentioned this at the end of Article 6. Lambda (Λ) is Einstein's "cosmological constant". He gave it up when it became clear that the universe was not static - Hubble's discovery in 1929. But today this constant is in fashion because it creates dark energy. However, in my opinion, dark energy does not exist. I described this in the article: "Horizontal Catastrophe B".  I do not accept at all a cosmology based on mathematical equations, based on general relativity. In my opinion, this theory as local does not fit the description of the universe that is not local.

But it is not everything. Let's summarize first. We have already talked about the homogeneity and isotropy of the universe, about the same properties of matter everywhere and of course about the same laws of nature everywhere. We spoke of the coordinated, concerted evolution of the entire universe, and then also of global time. It will soon turn out that, on the basis of our conclusions, we can also describe the cosmological motion of objects, the motion that determines the incessant change of the entire universe.

The question then arises: what conclusions can be drawn by observing the movement of distant galaxies? Is there a clear trend in their movement independent of the direction of observation? Although observation would do us a lot, at this point we will only think. Obviously it is a radial motion (near - far). Various movements can be considered (as long as they do not contradict the cosmological principle).

Is the averaged (statistically) speed zero? This is hard to accept as we have already concluded that the universe is changing - it is not static. If the universe is not static, then perhaps there is some mathematical relationship between the velocity of the galaxies and the distance (from us). Two options are preferred: accelerated (or retarded) motion and uniform motion (constant speed). If the motion is accelerated, it is a sign that every galaxy is affected by a force. In what direction? After all, there is no preferred direction (according to the cosmological principle). Looking at the same galaxy from two different points, we find that the directions of the force vectors are different. Thus, the direction of acceleration is not clear. This complicates our description a lot. In addition, according to the cosmological principle, there is no non-locally preferred direction of motion.

In this situation, it is worth checking the simpler option - uniform motion, since, according to the cosmological principle, the forces acting on each galaxy from all sides balance each other. [Even in the center of a massive sphere, gravity is reduced to zero according to Gauss's law.] This leads to the hypothesis that relative motion, with respect to any pair of objects, is uniform. [Everyone either gets closer or away.] And yet the speed is different for different distances (in a set of different objects). The farther away a galaxy is from us, the faster it moves (at a constant speed). "Faster" and not slower, which would be absurd, because then the nearest galaxies would move very fast. And this observation does not confirm. In the simplest case, the speed is proportional to the distance, which means that a galaxy twice as far is moving twice as fast. This case is preferred because it is not the result of simultaneous action of different local factors. Again: the universe is non-local. We can put it briefly as follows:

v/r = const

Of course, the existence of proportions follows the cosmological principle (the simplest option). This is a hypothesis that, at this point, is not based on any observation. If the observation rejects this model, we will go back to the earlier, more complicated option.

    Interestingly, scientists did not consider this option, even though the cosmological principle was well known and even constituted an important criterion in cosmological research. The discovery made in 1929 (more on this later) did not change the attitude of scientists who, even to this day, sort of have forgotten the cosmological principle. Even after the publication of general relativity, Einstein did not think about this model when he tried to describe the universe. At that time, everyone was convinced that the universe was infinite and static. Therefore, the discovery of Hubble in 1929 took the scientific world by surprise. Hubble's empirical law confirms our hypothesis (about the proportionality of distance and velocity).