Paradoxes, the solution of which can change our view of the Universe

Original author: The Physics arXiv Blog
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Revolutions in science often occur in the process of researching seemingly insoluble paradoxes. Focusing on them and, ultimately, finding a solution is exactly what led us to many important breakthroughs.

It will be interesting to list those of the paradoxes that are associated with modern ideas about cosmology. It is possible that their solution will lead to a breakthrough and development of ideas about the structure of the next-generation Universe.

Yuri Baryshev from St. Petersburg State University is working on issues of modern cosmology. The result of his work is a list of paradoxes based on well-known ideas and observations about the origin of the universe.

Perhaps the most dramatic and, at the same time, the most important paradox for cosmology is associated with one of the greatest achievements of this science - the assertion that the Universe is expanding.

And it is based on the following observations.

We know that other galaxies are moving away from us. The proof of this fact is that the light from these galaxies has a redshift , and the greater the distance, the stronger it is.

Astrophysicists interpret this fact as evidence that more distant galaxies are moving away from us at a faster rate. Moreover, recent data suggests that the expansion rate is increasing.

What is really interesting is that for such an expansion appropriate conditions must be created - space and vacuum. But how this happens, we still do not understand. The creation of space has not yet been described in cosmology; this is a new phenomenon whose existence has not been confirmed by us in the laboratory.

In addition, in a given volume of the universe, only the corresponding amount of energy can exist. If we observe an increase in the size of the Universe, then the total amount of energy corresponding to it should also increase. But if we turn to physics, then the Law of Conservation of Energy says: energy cannot appear from nowhere and disappear into nowhere.

The British cosmologist, Ted Harrison comments on this as follows: "Summing up, whether we like it or not, it becomes obvious: the energy in the universe is not conserved ."

This problem is well known to space scientists, but if you ask them directly, they will only shift from one foot to another and silently bury their eyes on the floor. Obviously, any theorist who can solve this problem will secure a bright scientific future in cosmology.

The nature of the energy associated with the vacuum is still a mystery. This phenomenon is called differently: either the energy of zero vibrations, or the Planck vacuum energy. Quantum physicists have spent enough time trying to calculate it.

The results of their work show that the vacuum energy density is huge, of the order of 10 94 g / cm 3 . Since energy is equivalent to mass, it should have a gravitational effect on the Universe.

Cosmologists searched for this gravitational effect (cosmological constant) and calculated its value based on their observations. According to calculations, the energy density of the vacuum (in the broad masses better known as "Dark Energy" ) is about 10 -29 g / cm 3 .

The figures obtained by scientists are difficult to combine, since their values ​​differ by 120 orders of magnitude. For what reason this contradiction arises, no one can explain, which is extremely confusing for every cosmologist.

In cosmology, there is another mystery - the redshift mentioned above. Physicists attribute this phenomenon to the Doppler effect , comparing it with the change in pitch of the police siren as the car passes by.

The Doppler effect occurs due to the relative movement of objects. But in our case, the cosmological redshift is different in that, according to cosmologists, space itself moves during the expansion of the universe, and the galaxies remain motionless in it.

Therefore, a different mathematical apparatus is also used to describe such an extension, not least because in ordinary physics the relative speed must always be less than the speed of light. But the speed of expansion of the space itself can be anything.

Interestingly, the nature of the cosmological redshift opens up the possibility of direct measurements in the coming years. The idea of ​​such measurements is that the redshift of very distant objects should increase with distance. For a distant quasar, this change can be about one centimeter per second per year. Such a change can already be observed with the help of the largest telescopes of the next generation.

And finally, we mention one more paradox. It originates in one of the assumptions of Einstein's General Theory of Relativity that if you observe the universe from a sufficient distance, then it should be the same in all directions.

It is clear that the assumption of homogeneity is not applicable at the local level. Our Galaxy is part of the Local Group of galaxies, and that, in turn, is part of an even larger supercluster.

Such a device assumes a fractal structure of the Universe, i.e. The universe consists of clusters, regardless of the point of observation.

The problem is that this contradicts one of the main ideas of cosmology - the Hubble Law , the observation that the redshift of an object is linearly proportional when it moves away from the Earth.

Hubble's law is deeply integrated into the structure of modern cosmology. At the moment, it is the most common theory and says that the expansion of the universe is linear. And all is well if the Universe is homogeneous and, as a result, linear at large scales.

But the results of the observations are contradictory. Astrophysicists measured linearity according to the Hubble Law at a distance of several hundred megaparsec. And the presence of clusters on the same scale indicates that the Universe is heterogeneous .

So the arguments in favor of the fact that the linear dependence in the Hubble law is due to the homogeneity of the Universe (or vice versa) do not stand up to criticism. And modern cosmologists are once again embarrassed by this failure.

Sometimes it is difficult to resist the temptation to say that the cosmological picture of the world as a whole is almost complete, that the Big Bang model and everything that follows from it correctly describes everything that we see around. No matter how! Cosmologists only managed to temporarily patch holes in their theories. Such a “success” is nothing more than an illusion.

But it should be so. If scientists really begin to think that they are close to a complete and final description of reality, then a simple list of paradoxes can do them a great service and return them from heaven to earth.

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