What is the mysterious supernatant "dark matter (dark matter)" that forms the universe?

ByMaxwell Hamilton

What a human knows about the universe is actually only a small part of the various elements that make up the universe. Unknown energy and substances are flooded in the universe, but about 25% of the universe is "Dark matter (dark matter)It is said to be a mysterious substance called.

BBC - Earth - What is our Universe made of?

Even if an alien exists and comes to the galaxy where the human being lives, there is a possibility that it will pass by not noticing the human race. The universe is vast, the planets floating in it are very small, for example the earth is like a small blue dot. So the alien is just one of the small points Even if you do not notice the moon turning around the earth and its surroundings, there is no irritation. Also, a large amount ofSpace debrisIt is very difficult to figure out the human being's pinpointing earth from among them. But even the facts listed here are only a small part of the elements that make up the universe and the remaining elements are energy or matter that no one has ever seen.

Everything that human beings can see with eyes, such as the body, the house, the car, the earth, all consist of "atoms". This atom is composed of two particles "proton" and "neutron", and many atoms can be decomposed even into finer particles.

ByMrs Pugliano

It was during the early twentieth century that humans noticed the existence of atoms that are the building blocks of matter, initially thought to be "the main component of all substances present in the universe." However, in 1933 he was a Swiss astronomerFritz TubikkiArgues the existence of dark matter for the first time saying that "most of the universe is formed by something else", denying the idea that all substances present in the universe are composed of atoms.

Tsubikki calculated the brightness and mass of one star by measuring the brightness of each galaxy in the galaxy. And as a result of the calculation, we discover that observable substances alone can not obtain sufficient gravity to form galaxies. In addition, we also observe that the galaxy rotates at high speed.

From these facts, we can not observe Tsukikki, but I am convinced that "there is something with a stronger gravity to keep the galaxies together". Tsubikki seems to have testified that this unknown substance is "dark", but scientists and astronomers at the time admitted that he did not claim that he handled him as a strange owner.

Until the 1970s Tsubikki's claim was almost forgotten, but astronomersVera Rubin, But discovered that the galaxy near the earth is not rotating correctly, this is "Galactic rotation curve problemIt will be called.

A very simple rule is applied in the solar system, "The planet floating in a place far from the sun weakens gravity and the planet moves very slowly, so its orbit becomes very long." The same theory applies to planetary orbitals in other galaxies, and stars that are furthest away from the center were thought to move slowly as the gravity weakens.

However, in the galaxy found by Rubin, the star farthest from the center was moving as quickly as the other stars. In order to rotate at such a speed, we must think that some force is working so that stars do not jump out of the galaxy, and it is presumed that the identity of this "some kind of power" is dark matter. And the existence of dark matter will be recognized. And now we believe that the foundation of what most astronomers form the universe is dark matter.


Dark matter can be compared to "wind" in that we can not see it directly by eye, but because we know that it exists. Such dark matter is thought to be a substance constituting 25% of the universe, sometimes 80% is said to be composed of dark matter. It is to be noted that 30% of the elements constituting the universe are considered to be substances (5% is a substance composed of atoms recognized by humans, the remaining 25% is dark matter) and the rest are dark energy (dark energy) I will.

By the 1980 's, there were several pieces of evidence to show that dark matter existed. For example, in 1981, a research team headed by Dr. Mark Davis of Harvard University conducted the first galaxy investigation, and it turns out that the galaxy does not stay in a certain shape in the investigation. In addition, the galaxy also reveals that hundreds of thousands of galaxies gather like gigantic lumps and have a huge structure like a spider's web, and we believe that it is the dark matter that connects these galaxies together It is now available.

In 1980, Russian research team led by Dr. VA · Lubimov, advocate that neutrinos, which are ghost-like particles that do not interact at all, are "constituent particles of dark matter". Dr. Lubimov's explanation was "If all the neutrinos in the universe are connected, it might be able to explain the existence of dark matter". However, there was a problem with this. If the dark matter is made up of neutrinos, neutrinos emit light and move quickly, so the dark matter becomes "hot".

Dr. Frenk found out that it is not like the present universe as a result of simulating the case where hot dark matter exists in the universe. Dr. Frenk commented on this, "It was that we discovered that there was no hot dark matter in the real universe, which badly disappointed us." from here,Cold Dark Matter(Cold dark matter) is born.

ByNASA Goddard Space Flight Center

Although humans can not see the dark matter directly, they can recognize their existence from the dark matter's "bending light" nature. This phenomenon is somewhat similar to the phenomenon that the light inserted into the pool diffracts,Gravity lens effectIt is called. By applying this technology, scientists will show where in the universe dark matter existsmapIs created. Also, this team seems to have the ambition to map one-eighth of the universe.

There are billions of stars even in the Milky Way Galaxy with the Earth, so mapping one-eighth of the universe will cover millions of galaxies.


Despite the existence of various kinds of information, human beings are considered to be "almost understanding only about the outline" with respect to dark matter, and it is completely unknown what kind of substance actually is. A number of ideas have been proposed, but the most popular idea at the moment is that "dark matter is made up of new kind of particles, it is predictable in theory but it has not been detected yet". This new kind of particle is "Weakly Interacting Massive Particles", abbreviated asWIMPsIt is called.

WIMPs are barely interactive particles and are considered to have weak actions with normal substances. For example, if a hand strikes this WIMPs when hitting a wall, WIMPs particles have the property of slipping through hands or walls. Furthermore, although WIMPs exist in large quantities, they are not necessarily large. Therefore, it can be hundreds or thousands times as heavy as protons. Furthermore, it can be pointed out that human beings can not recognize particularly important characteristics.

Professor Anne Green of the University of Nottingham, deeply conscious of this WIMPs said, "WIMPs are initially defined as" invisible substances ", and now they are composed of new kinds of substances which are undetectable It is defined as "This is ridiculous."

By▓▒░ TORLEY ░ ▒ ▓

Back in 1983, some physicists insisted that "there is no such thing as dark matter," this pointed out that the law of universal gravitation must be wrong. In addition, it seems he insisted that the galaxy has become strange as the law of universal gravitation is wrong. This idea is "Modified Newtonian Dynamics (Modified Newtonian mechanics) "Abbreviated as MOND, which says," You must define substances that are unknown because the law of gravity is wrong. "

The problem of this idea is that it is not "something that can be thought of as a substitute for dark matter". If you want to propose a new law of gravity, it is necessary to explain all the events better than Einstein, and it is obvious that this is very difficult, as it also needs to explain about dark matter as well.

ByDavid Stone

In 2006, NASA released a certain photo. This photograph shows how two huge clusters of galaxies are colliding, and most of the substance can be seen clearly in the center where gravity is considered to exist. However, at the outer edge of this picture the light is twisted by gravity, indicating that "There is something unknown substance, this is twisting light". In other words, this photo was a direct proof of the existence of dark matter, it was greatly welcomed by scientists and astronomers who believe in dark matter.

In fact, there are three ways to recognize dark matter. One is to observe the action of dark matter on the universe. Using a map showing where the dark matter exists, the astronomer monitors the timing at which the dark matter collides now or not. As explained, dark matter goes through ordinary substances, but it may collide with the nucleus rarely as it passes through thousands of substances. At this time, the nucleus bounces back like the ball that floated on the pool was kicked, high energy gamma rays are generated, so we observe this.

In 2014, researchers found that gamma rays generated by collision between dark matter and nuclei were detected using NASA's Fermi gamma ray space telescope dataAssertionI have done it. In this study, gamma rays shining like burning in the galaxy were claiming that it was "probably born of collision of dark matter and nuclei". Although this was reasonable as a logical model, it has not been explained to explain whether or not gamma rays originated from dark matter.

Fermi Galactic Center Zoom - YouTube

Also, there is a similar method to recognize dark matter, "Detect collision between dark matters". A research team of Professor Richard Massy, ​​who works at Durham University in the UK, said the moment when two galaxies collide violentlyObservationDid. The research team thought that all the dark matters existing in the galaxy would pass through everything but in fact it seems that it was able to observe that some objects decelerated. This indicates that the dark matter collided with each other, he said.

However, there are drawbacks in "observing the action of dark matter on the universe" and "detecting collision between dark matters". That is, data on dark matter detection of galaxy size is too huge.

ByPink Sherbet Photography

As a more realistic way to recognize dark matter, physicists built CERN in Geneva, SwitzerlandLarge-scale hadron collision type accelerator(LHC) is expected. LHC is a device capable of causing elementary particle reaction at high energy by hitting protons accelerated to a speed close to light. In other words, using LHC makes it possible to investigate subatomic debris.

In the course of experiments using this LHC, "It may be possible to discover unknown particles like WIMPs" is Professor Malcolm Fairben of King's College London. According to Professor Fairben, "If WIMPs constitute dark matter and it was possible to detect this using LHC, it would be a great opportunity to know what the dark matter that makes up the universe is made" And that. But, of course, if WIMPs are not constituents of dark matter, you can not use LHC to detect dark matter. Also, even if the LHC can produce dark matter, it will not get caught by the detector. "Instead, the system may detect a group of particles moving in one direction, but it will not detect anything else," Fauben said.


And the third way to recognize dark matter is "adventure into the ground". Billions of dark matter particles are constantly slipping through our world, "It's also in your room and work, these pass through your body at billions of seconds per second, but you I can not feel anything, "Dr. Fleck. In theory, if the dark matter and the nucleus collide, the emitted gamma ray should be detectable. The problem is that other energy such as radiation and cosmic rays will also pass through matter like dark matter.

So it is important to understand that it is an underground experiment. The rock blocks most of the radiation, but perhaps dark matter can pass through it. So underground experiments may be suitable for detecting collision between dark matter and nuclei.

However, so far, most physicists have not been able to detect any reactions, and in August 2015 the Italian dark matter detection project "XENONPublished bypaperHowever, it is revealed that we have not succeeded in detecting dark matter.

ByJon Vidar Sigurdsson

There is plenty of opportunity to succeed in detecting dark matter for the first time in LHC or underground experiments. However, it seems that it is not enough to just find dark matter at one location, Professor Fairben said in the end, "We discovered a way to detect dark matter in the universe as well as we are observing at the laboratory I must do it. "

80 years have passed since Tsubikki suggested the existence of dark matter, but at this time humans have not been able to detect dark matter or sample them as a sample. This may be an indicator that informs us that it is still necessary for humans to understand the universe perfectly.

in Science,   Video, Posted by logu_ii