The story of the universe provided by the different observational missions is exciting and confusing. In addition, it has many episodes; It almost looks like a desktop snake. Every time a surprise arises that keeps us hooked to the key enigmas of the cosmos. Will we solve them?
Some of the different models that cry out to offer the best description of the universe present strong discrepancies with each other. These dissensions are known as “tensions” in the jargon that cosmologists handle. And the discussion is burning.
How is the matter that forms galaxies and the stellar clusters brings together? What rhythm does the universe expand? Isn’t dark energy as they have told it so far?
Far from finding a unified solution, the already populated collection of mysteries in cosmology is continuously increasing. Although sometimes there are favorable surprises and some of those conflicts end up diluting.
The latest results of the spectroscopic instrument of dark energy (desi) on the expansion of the universe show a marked preference for dynamic dark energy, a model where this dark energy is not constant, but changes over time. This is a revolution to explain the cosmos.
What rhythm does the universe expand?
The veteran between these discomforts is the so -called Hubble tension, which has more than a decade with us. It is summarized in a strong disparity in the rhythm of expansion of the current universe. In this debate there are two observational contestants.
The first of the fighters willing to defend their champion title is the collection of exquisite measures of the cosmological microwave background (CMB). And on the other side of the quadrilateral they are preparing to battle certain measures of the local universe. Specifically, they correspond to measures of a type of supernovas.
The first data set uses electromagnetic radiation that has come to us since the confines of the universe and on its trip has contemplated virtually its entire history. Not only has he witnessed its expansion, but of the formation of structures.
Instead, Supernovas data reports us from the physics of a mature universe, and resort to the light of nearby stars. These predict a rhythm of expansion of the universe faster than its rivals.
Today the difference in values is so accused that the probability that this result is due to a pure coincidence is very low. It can be estimated at 0.0000002 %, which is equivalent to 1 in 500 million. Clearly this inclines to think that there is something very important that is overlooking.
This generates great expectations about new and independent experiments. Currently, reliable observations of the luminosity of morbundas stars are put on the side of the Supernovas. The universe would expand too fast for the taste of some researchers. So we do not lose track of this incipient research route that, I insist, increase the problem. And so wide is the gap that some already call it the “Hubble crisis.”
How is matter brings together in different places of space?
Another tension that has had very entertaining cosmologists is linked to the variations between the areas with more matter and the most empty in the universe.
We can see it as if the cosmos had lumps, just like the famous chocolate drink.
For historical reasons, the amount of matter present in spheres is measured of 8 megapats or MPC (about 26 million light years) Radio in a community reference system. This results from choosing coordinates such that the distances between stars are fixed despite the expansion of the universe. It is like nailing a pin in the position of each object in an elastic sheet that is being stretched and taking as an immovable distance the initial.
The value of 8 MPC is not random; On the contrary, it is key. It corresponds approximately to the scale of the most massive galaxies, which gives fluctuations in large matter density with respect to its average value in the universe.
NGC 6355 globular cluster in the internal regions of our galaxy, the Milky Way. ESA/HUBBLE AND NASA, E. NOYOLA, R. COHEN, CC BY
In this way, precise measures are achieved that correspond to perfectly settled structures after collapsing. In opposition, at smaller scales (less than 1 MPC, about 3.26 million light years) The non -linearity of gravity should be taken into account. Specifically, it would be necessary to study how clusters are gravitatorially feedback from galaxies. But at much larger scales (more than 100 mpc, about 326 million light years) We would not see fluctuations, but a homogeneous cast.
The discrepancy of the tracers
So far the measures that gave us that Pepito Grillothe cosmic microwave background faced a problem. They presented a strong statistical discrepancy with other measures. These are the ones that would be obtained through the so -called tracers. This is called observable objects or phenomena that provide maps of the distribution of matter in the universe.
Most of the matter is dark and does not emit light, we cannot observe it directly. Instead, we can see how galaxies, clusters and other objects that make markers of the underlying matter are grouped. The good news that the Kids experiment (kilo-degree survey), of the European Observatory Southern (ESO) brings, is that this tension has been resolved. Their data confirms that the groups follow the rules of the standard model of the cosmos. For this they have carried out a series of improvements.
And the greater the accuracy and the amount of data in the universe, the greater the surprises that emerge.
The tension of dark energy
Without being strictly new, the question of tension between a dark energy that evolves and an impassive has been accentuated.
The new DESI experiment data and their corresponding analysis are recently out of the oven. They tell us about the acoustic bariones oscillations (BAO). They are like sound waves arising in the primitive universe that were frozen. This break was caused by cooling due to the expansion of the universe. The temperature decrease allowed light and matter to be separated.
Today these patterns are printed in the distribution of galaxies of the universe, giving us rules to measure their expansion. And from his study it follows that the power of dark energy to cause gravitational repulsion is being diluted.
This problem that we have on the table for now a year conflict with what other CMB data says. Being electromagnetic radiation we can study its electric field by spreading through the universe. This gives us knowledge about the changes in density of matter that is finding. The most recent collection of data has reached us from Atacama Cosmology Survey. The dark energy model of the cosmological constant fits these observations as a glove.
Having seen all this panorama we can overwhelm a bit for not having answers for so much question. But if cosmology manages to advance it is precisely for ignoring those who say “do not look up.”
This article was originally published in The Conversation.