Physics is permeated with puzzles, and in a sense this is what keeps the field going. Theseto support the race towards the truth. But of all the dilemmas, I would say that two of them undoubtedly fall under Priority A.
First, when scientists look at the sky, they constantly see stars and galaxies moving farther away from our planet and away from each other, in every direction. The universe looks like a bubble that explodes, so we knew it was expanding. But something doesn’t make sense.
The universe doesn’t seem to have enough of the things that float in it — stars, particles, planets, and everything else — to inflate so quickly. In other words, the universe is expanding much faster than our physics says it can, and is even picking up speed as you read this. Which brings us to problem two.
According to the best calculations of experts, the galaxy rotates as incredibly fast as everything moves around it, that we would expect the spirals to behave like uncontrollable carousels throwing metal horses from the ride. There don’t seem to be enough things in the universe to connect them. Nevertheless, the Milky Way is not moving away.
So what is it all about?
Physicists generally call the “missing” substances that push the universe out of dark energy, and the pieces holding galaxies together – probably in the form of halo-like – dark matter. Neither interacts with the light or matter we see, so they are essentially invisible. The combination of dark matter and dark energy makes up an incredible 95% of the universe.
The authors of a recent review published in the journal Science Advances focus on the proportion of dark matter and write that “it may well consist of one or more types of parent particles” although some or all may consist of macroscopic lumps of some invisible form of matter such as black holes. . “
Black holes or not, dark matter is completely elusive. In an effort to unravel its secrets, scientists have selected a handful of suspects from the cosmic array, and one of the most sought-after particles is a strange small spot called an axion.
Hypothesis of axions with rounded eyes
You may have heard of the Standard Model, which is largely the Holy Grail, an ever-expanding handbook of particle physics. Outlines how each single particles in space work.
However, as the Science Advances review points out, some “particle physicists are restless and dissatisfied with the Standard Model because it has many theoretical shortcomings and leaves many pressing experimental questions unanswered.” More precisely, for us, this leads directly to a paradox concerning a well-established scientific concept called CPT invariance. Ah, the physical puzzles continue.
The CPT’s invariance basically says that the universe must be symmetrical in terms of C (charge), P (parity) and T (time). For this reason, it is also called CPT symmetry. If everything had the opposite charge, the left-handed place was right-handed and traveled backwards instead of forwards, saying that the universe should remain the same.
For a long time, the symmetry of the CPT seemed unbreakable. Then came 1956.
In short, scientists have found something that violates the P part of the CPT symmetry. This is called weak force and determines things like neutrino collisions and fusions of elements in the sun. Everyone was shocked, confused and scared.
Almost every basic concept of physics is based on the symmetry of the CPT.
About ten years later, researchers discovered a weak force that also disrupts C symmetry. Things were falling apart. Physicists could only hope and pray that even if P is violated … and CP is violated … maybe the CPT still isn’t. Perhaps only weak forces need a trinity to maintain the CPT’s symmetry. Fortunately, this theory seems correct. For some unknown reason, the weak force follows the overall symmetry of the CPT despite the C and CP blips. Yuck.
But here’s the problem. If weak forces disrupt the symmetry of CP, you would expect them to be strong forces as well, right? Well, they don’t, and physicists don’t know why. This is called the powerful CP problem – and exactly where things are getting interesting.
Neutrons – uncharged particles inside atoms – are subject to strong forces. In addition, for simplicity, their neutral charge means that they break T symmetry. And “if we find something that breaks the T symmetry, then it must also break the CP symmetry so that the CPT combination is not broken,” the paper states. But … that’s weird. Neutrons not due to a strong CP problem.
And so the idea of an axion was born.
Years ago, physicists Roberto Peccei and Helen Quinn proposed adding a new dimension to the standard model. It included an array of ultralight particles – axions – which explained the strong problem of CP, thus easing the conditions for neutrons. The Axions seemed to have fixed everything so well that the pair’s idea had become “the most popular solution to a strong CP problem,” the paper said. It was a miracle.
To be clear, axions are still hypothetical, but think about what just happened. Physicists have added a new particle to the Standard Model that sketches spots the whole universe. What can this mean for everything else?
The key to dark matter?
According to Peccei-Quinn’s theory, axions would be “cold” or move very slowly through space. And studie the researchers of the study say “existence [dark matter] it is derived from its gravitational effects, and astrophysical observations suggest it is ‘cold’. “
The document also states: “There are experimental upper limits on how strongly [the axion] interacts with visible matter. ”
In principle, therefore, the axions that help explain the strong CP problem also seem to have theoretical properties that are consistent with the properties of dark matter. Extremely good.
The European Nuclear Research Council, better known as CERN, which runs the Large Hadron Collider and conducts antimatter research, also emphasizes: “One of the most suggestive features of axions is that they could be produced naturally. in huge numbers soon after the Big Bang. This population of axions would still be present today and could form the dark matter of the universe. “
Here you go. Axions are among the hottest topics in physics because they seem to explain so much. But again, these wanted pieces are still hypothetical.
Will we ever find axions?
It’s been 40 years since scientists began hunting axions.
Most of these surveys “use mainly the interaction of the action field with electromagnetic fields,” the authors say in a recent review published in Science Advances.
For example, CERN has developed the Axion Search Telescope, a machine designed to find a hint of particles produced in the solar core. Inside our star are strong electric fields that could potentially interact with axions – if they really are.
But so far the quest has faced several quite big challenges. First, “the mass of the particles is not theoretically predictable,” the authors write – meaning that we have very little idea of what an axion might look like.
Right now, scientists are still looking for them, assuming an extremely wide range of masses. Recently, however, researchers have offered evidence that the particle is probably between 40 and 180 microelectronvolts. This is unthinkably small, about 1 billionth of the mass of an electron.
“Besides,” the team writes, “the axion signal is expected to be very narrow … and extremely weak due to the very weak particle and field coupling of the standard model.” Basically, even if the tiny axions are trying their best to signal our existence to us, we can miss them. Their hints may have been so faint that we could barely notice them.
Despite these obstacles, the axionic search continues. Most scientists say it must be there somewhere, but it seems too good to be true when it comes to fully explaining dark matter.
“Most experimental experiments assume that axions make up 100% of the halo of dark matter,” the study’s authors point out, suggesting that there may be a way to “look into axion physics without relying on such an assumption.”
Although they can be the star of a show, what if axions are just one chapter in the history of dark matter?