What is Dark Matter? Mystery still unsolved! - Groovy Science


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Sunday, June 30, 2019

What is Dark Matter? Mystery still unsolved!

Our universe is expanding, and we all know that. However, expansion is Accelerating. When big-bang happened, this expansion was nearly constant, but after 13.772 billion years, the expansion is accelerating, as of now it might have enough energy density to stop expanding and recollapse, it might have so little energy density that it would never stop expanding, and also gravity was certain to slow the expansion as time went on. But, the universe slowing down hasn't observed. But, theoretically the universe had to slow. In 1998 the Hubble Space Telescope(HST) observed very distant supernovae, which showed that a long time ago, our Universe was expanding more slowly than it is today. We concluded that the expansion of the Universe hasn't been slowing because of gravity; in fact, it is Accelerating. Well, no one could explain what this was and what is the cause of Expansion of our Universe. There had to be something that is pushing the edge of our universe or at least filling our universe, resulting with expansion.

It's been 113 years that we've known this mysterious Entity, and so far we only know so little about it. We've known it since 1906 when physicist Henri Poincaré’s 1906 speculated about the amount of “matière obscure” in the Milky Way. It went even back in 1846 and the first successful detection of dark matter: the discovery of the planet Neptune, whose existence had been inferred by its gravitational pull well before it was actually observed. The whole universe is consist of 68% of Dark energy,27% Dark Matter and the rest is ordinary matter like our earth, sun, stars and all the visible matter, which combines of only 5% of the universe. Scientists and astronomers have not yet observed dark matter directly. Because, it does not interact with baryonic matter and it's completely transparent to light and other forms of electromagnetic radiation, making it difficult to detect with modern instruments. But scientists are certain it exists because of the gravitational effects it appears to have on galaxies and galaxy clusters.

What is Dark Energy?

One of many explanations for dark energy is that it is a property of space. Our genius, Albert Einstein, was the first ever person to realize that empty space is not nothing. Space possesses amazing properties, many of which are just beginning to be understood. The first property that Einstein observed that it might be possible for extra space to come into existence. Then one version of Einstein's gravity theory, the one which contains a cosmological constant makes another prediction, which concludes that empty space might hold its own energy. Since this is the property of space it does not dilute as space expand. The more space expands more of this energy comes into existence, and that is why most of the universe is filled with Dark Energy. Now, that more and more energy is coming into existence by the expansion, the more it fills the space in the universe, which causes the universe to expand rapidly.

Another theory says that this might be a new kind of dynamical energy fluid or field. Something that is weird, something that fills all of the space but also that its effect on the expansion of the universe is opposite of that of normal matter and normal energy. Some of the scientists have named this "Quintessence", after the fifth element of Greek Philosophers. We have no idea what it interacts with, or even why does it exist. We need more instruments and better technology and the brightest minds to work on this subject to collect the data so that we can solve this undefined mystery.

What is Dark Matter?

Dark Matter, We know more about what it's not than what it is. From the name, we might conclude that it is dark, which means it is not in the form of stars and Planets. Since 27% of the universe is filled with Dark matter we know that it is the second highest quantity after Dark Energy. We know that it is not in the form of dark clouds of normal matter, anything that is made up of baryons. Dark matter is not antimatter, because we do not see the unusual gamma rays that are produced when antimatter obliterates with the matter. According to standard physics, the stars that are placed at the edge of a spinning spiral galaxy should move slower than the stars which are placed at the galactic center where all the matter is concentrated. Turns out our observation shows that stars orbit at more or less the speed regardless of their position in the galaxy. This would make sense if we assume that the stars which are the edge are experiencing the gravitational effect of an unknown and unseen mass(Dark matter).

Scientists have several ideas for what dark matter might be. One of the interesting hypothesis is that Dark Matter is consist of exotic particles which does not interact with matter and light, but that still exert a gravitational pull. Several scientific groups, including one at CERN's Large Hadron Collider, are currently working to generate dark matter particles for study in the lab.

Recently scientists at Flatiron Institute were able to create a model called Deep Density Displacement Model, or D3M for short. They used artificial intelligence techniques to generate complex 3D simulations of the universe in an amazing Thirty milliseconds, including how much of the Universe is dark matter. The actual shock was that Deep Density Displacement Model could accurately simulate how the universe would look if specified parameters were tweaked even though the model had never received any training data where those parameters varied. The results are so fast, accurate and strong that even the creators aren’t sure how it all works.

So, What can we do with it, if we ever acquire it?

If it was possible to acquire Dark Matter, we would be able to create small artificial singularities(Micro black holes), which would drive portable fusion power sources. It is probably possible, but first, the physics of Dark Matter would need to be figured out, and after that. A specific technology would need to be developed to contain and harness the power generated by that fusion reactor. Small singularities are not as dangerous as everyone automatically assumes, but there would need to be some safety precautions once the physics is clearly defined. Creating something stable would be difficult. The ground state of dark matter which pervades the milky way, and is concentrated in the halo, is probably not directly useful dark matter. There would be a lot of engineering work needed to create useful dark matter structures. We don't really know what Dark matter is yet. Since we can't directly observe it, we can't really work out what kind of properties it might have (apart from the obvious one of not interacting with normal matter or energy in the usual manner.) Without knowing that much, figuring out a practical application for the material is pretty much a non-starter.

Dark Matter is a very Weird entity that we don't really understand yet. Once we understand its properties, I hope vast opportunities would be created for Humankind. The universe is filled with unknown possibilities and entity, it inspires us to explore more and gain more and more knowledge. We have barely started an awesome journey of exploring the universe. With the first every picture of a black hole this year, we've proved that we can achieve any goal that we choose to Obtain. Dark Matter is one of them, and I'm pretty sure we will reveal the mystery behind this unknown entity in the future.

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