What is Dark Matter? Axions may be the answer to the biggest mystery in the Universe | Science and Education
|What is Dark Matter? Axions may be the answer to the biggest mystery in the Universe | Science and Education|
Dark Matter: What Is It? Axions could hold the key to solving the universe's largest puzzle
The story of how a strange speculative particle became a candidate for stellar dark matter.
Physics is full of mysteries and in a way, this field is growing because of it. Start a race to uncover the truth of this perplexing riddle. But in all dilemmas, I would say that the two undoubtedly have priority A.
First, when scientists look up at the sky, they consistently see stars and galaxies that are further away from our planet and further away on either side. The universe looks like an exploding bubble, expanding as we know it. But some things don't make sense.
It doesn't seem like there are enough things in space to expand so fast - stars, particles, planets and everything else. In other words, the universe is expanding faster than our physics, and it's accelerating as you read on. This problem brings us two.
According to the best calculations of experts, galaxies spin so fast because everything spins so fast, we expect these spirals to act like a runaway carousel, kicking the metal horse out of its journey. There doesn't seem to be enough in the universe to hold them together. However, the Milky Way did not collapse.
As a general term, what physicists call "absence" pushes out the universe with dark energy as well as debris—perhaps in the form of a halo—in the form of dark matter uniting galaxies. They do not interact with light or objects that we can see, so they are inherently invisible. Dark matter and dark energy together make up 95% of the universe.
The authors of a recent review in the journal Science Advances focusing on the dark matter section wrote that "it may consist of one or more types of elementary particles although some or all of them may include some macroscopic ones." It's like a black hole."
With or without a black hole, dark matter is completely elusive. To unravel its secrets, scientists have picked up a few suspicious individuals from the cosmic roster, and one of the most iconic particles is a strange little blob called an axion.
Axion's Big Eyes Hypothesis
You've probably heard of the Standard Model, the Holy Grail, a growing handbook of particle physics. It explains how every particle in the universe works.
However, as noted in Science Advances Review, "some particle physicists feel uncomfortable and dissatisfied with the Standard Model because of its many theoretical flaws and its many pressing experimental questions that cannot be answered." More precisely, in our case it is straight forward. In a contradiction about a well-established scientific concept called CPT invariance. Ah, the physics puzzle continues.
Basically, the CPT invariance states that the universe must be symmetric when it comes to C (charge), P (parity), and T (time). Hence it is also called CPT symmetry. If each object has an opposite charge, is left-handed instead of right-handed, and moves backwards rather than forwards in time, it suggests that the universe should remain the same.
The CPT symmetry has long seemed to be inseparable. Then came 1956.
Long story short, scientists have found something that violates the P part of the CPT symmetry. This is called the weak force, and it governs things like neutrino collisions and the fusion of matter in the Sun. Everyone is shocked, confused and scared.
Almost all fundamental concepts in physics depend on the CPT symmetry.
Nearly a decade later, the researchers also discovered weak forces violating the C symmetry. Things are falling apart. Physicists can hope and pray that even if P gets hurt... and CP gets hurt... CPT still can't happen. Maybe the weaker ball just needs a trio to maintain CPT symmetry. Fortunately, this theory appears to be correct. For some unknown reason, the weak force follows the perfect CPT symmetry, regardless of external factors in C and CP. phew
But here is the problem. If the weak force violates the CP symmetry, you would expect the strong force to do the same, right? Well, they don't know, and physicists don't know why. This is called the strong CP problem - this is where it gets interesting
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Neutrons – the uncharged particles in atoms – are subject to strong forces. For simplicity, their neutral charge also means that they violate the T-symmetry. And "if we find something that violates the T-symmetry, it must violate the CP-symmetry that does not violate the combinatorial CPT," the paper says. But... that's weird. Neutrons are not the cause of strong CP problems.
And so the concept of Axion was born.
A few years ago, physicists Roberto Pacey and Helen Quinn proposed adding a new dimension to the Standard Model. It is a region of ultralight particles - the axis - that explains the strong CP problem and the position of the neutrons at rest. Axions seemed to solve everyone's problems so well that the idea of these two has become "the most popular solution to the powerful CP problem". It's a surprise.
To be clear, the axis is still speculative, but think about what happened. Physicists have added a new particle to the Standard Model, outlining the droplets of the entire universe. What does this mean for everything else?
The key to dark matter
According to the PC Queen theory, the axes would either "cool down" or move very slowly through space. And... the researchers say, "The existence of [dark matter] was inferred from its gravitational action, which is 'cooled' by astronomical observations."
The paper further states that "there is an experimental upper limit to how strongly [the axis] interacts with visual matter".
Basically, the axes that help explain strong CP problems also have theoretical properties favorable to dark matter. Very good.
The European Council for Nuclear Research (CERN), which operates the LHC and directs antimatter research, also emphasizes that "one of the most instructive properties of the axis is that it can be generated naturally."
To continue. Axions are one of the most debated topics in physics because they explain so much. But then, these hugely popular parts are still speculative.
Can we find Axion?
Scientists have been searching for the spindle for 40 years.
Most of these discoveries "use primarily spectacle and the interaction of the electromagnetic field," the authors said in a review recently published in Science Advances.
For example, CERN has developed the Axion Search Telescope, an instrument used to locate the source of particles generated at the center of the Sun. There are strong electric fields within our stars that could potentially be communicating along an axis - if they exist.
But till now this work has faced many challenges. On the one hand, "particle mass is theoretically unpredictable," the authors wrote, meaning we know very little about what an axis looks like.
Scientists are still looking for them assuming the general public. However, the researchers' recent findings indicate that the particle voltage may be between 40 and 180 microelectron volts. It is incredibly small, about a billion times the mass of an electron.
"Furthermore," the team wrote, "the action signal is expected to be very narrow and the Standard Model is very weak due to very weak connections in particles and fields." Basically, kids try their best to show even the smallest of movements. Presence, and we can even remember it. Their clues may be so faint that we can hardly notice them.
Despite these obstacles, Axis Search will continue. Most scientists think they must be somewhere, but they seem too good to be true when it comes to fully explaining dark matter.
"Most experimental efforts assume that axes generate a 100 percent dark matter halo," explain the study authors, "that axes may be a way to study physics without relying on these assumptions."
Although they may be the stars of the show, what if the ax was just one chapter in the story of Dark Matter?
Source: Monisha Ravisetti, Cnet, Direct News 99