Will the universe have a catastrophic end? This says science

Let’s put in Shaker a shocking title, an old question and a few drops of physics. If we shake it well, we’ll just have to taste it. But will it leave a good taste in our mouths for knowing the fate of the universe? We gather here the testimony of all the people who have asked themselves about it since ancient times. However, we have an advantage: we can finally provide answers using the latest science and Expectations are that we may be heading towards a violent end, a big rip or tear.

The experimental data fit well with big rip, indicating that it is very likely to happen. The basis is that the universe contains enough dark energy to “stretch” it, expanding it in an increasingly accelerated manner. The galaxies will move away more and more, and the gravity will gradually become less and less until its influence wears off. Planets and satellites will lose their orbits and stars will be separated from galaxies. Then come those great tears of the universe.

Dark energy is expanding the universe rapidly

Sure enough, the large-scale universe is getting bigger and bigger. Specifically, its rate of expansion is accelerating. Einstein’s equations suggest that the reason is that they are mostly made up of dark energy, which produces repulsive gravity. But can we polish more?

Let us humbly admit before moving forward that our paradigms hide our ignorance by presenting it as wisdom. In them we imagine dark energy as a liquid described in a very elementary way. For this we use the variables inherited from thermodynamics.

On the one hand, we will have the pressure of this fluid and on the other hand its density, that is, the amount of energy per unit volume. If we only had particles with small velocities, that energy would basically be the energy of their masses. Thus, it is sufficient to think of gravity in the manner of Newton, without relying on Einstein. But this is not possible because in our universe very fast particles, such as photons and neutrinos.

In light of this, we therefore suggest that the universe is a soup of different liquids with their different properties. Thus we make Einstein’s equations tell us what properties the different fluids must have for the accelerated expansion to occur. And not only that, they tell us in what proportions these components should be. Aside from the photons (neutrinos and other crap), we’ll have dark matter in the component segment that produces gravitational attraction. They are incompatible with dark energy.

The rate of expansion can become unlimited

The most interesting type of dark energy is the cosmological constant and it presents a very unique barrier. The most common working hypothesis for describing any of the above fluids is that pressure and energy density are proportional to each other.

But beware! While the energy density is always positive, dark energy has a negative pressure. In fact, it should be negative enough. The number that controls the ratio of pressure versus energy density plays a crucial role in the solutions of Einstein’s equations. This parameter primarily tells us whether or not the universe is expanding rapidly. In other words, it dictates whether the pressure is negative enough to create the necessary repulsion.

But more negative pressure can lead to dramatic behavior: the rate of expansion can suddenly become unlimited. In fact, the same thing would happen to the size of the universe itself (and its scale factor). s That would have disastrous consequences, destroying all known structures. In fact, it would all be nonsense under the circumstances. Also, the change will suddenly become infinite.

There is a clue

The probability of this situation occurring is well known from a theoretical perspective. Surprisingly, the empirical data seems to favor this position. In other words, there is evidence that the universe could end with Big rum.

Well, it is convenient to make a nuance to avoid the protests of some colleagues. Depending on the sources consulted, this scenario is not necessarily the one that statistics strongly support. But, interestingly, the consensus is that the current range of uncertainty includes big rip Among the highly potential final destinations.

Phantom dark energy is to blame

The type of dark energy causing this violent end to the party is called illusory dark energy. To give more details, it is necessary to resort to the system of modules selected for this. Using it we see that big rip It will occur if the pressure exceeds the energy density in absolute terms. If they are identical, then we are faced with an end state, namely the famous cosmological constant. Einstein introduced this well-known type of fluid. Paradoxically, his goal was to achieve a static universe, without expansion. The genius abandoned him, calling it the biggest mistake of his life.

130 billion years until the Great Rip

But back to what matters. If the universe were to break into a thousand pieces, what things should we stop worrying about? Will those who are still considering continuing to pay their mortgage for another 20 years breathe a sigh of relief? I’m afraid I’m not the bearer of good news. It would take about 130 billion years for the Great Rip to occur. This is 10 times the age of the current universe.

This estimate is based on selecting a pair of values ​​within the windows that are statistically valid. In the first place we put that dark energy accounts for 70% of the content of the universe. And second, we will make the relationship between pressure and energy density only 10% larger than the cosmological constant. However, voila! expect big rip Which will take a long time to arrive.

To fine tune this entire panorama, we need to observe the universe on a large scale in greater quantity and quality. Data provided by the James Webb Telescopes (in progress) or the Nancy Grace Roman telescopes (planned), along with data from other international efforts, will undoubtedly contribute to this. And perhaps the most interesting thing is that the mystery of the ultimate fate of the universe has not been solved. Nor is there an opportunity to solve other people’s problems that we haven’t talked about. The really exciting thing is the possibility of unknown mysteries emerging. Because, as physicist and Nobel laureate Kip Thorne said, “The right answer is seldom as important as the right question.”

* To read the original note, Posted in Conversation, click here.

* Written by Ruth Lazkoz, Professor of Theoretical Physics at the University of the Basque Country.

* The Conversation is an independent, non-profit source for news, analysis, and commentary from academic experts.