Humans have made a staggering amount of scientific and technological progress over the past century. We’ve created technology that has transformed our society; scientific advances have helped us answer fundamental questions about who we are and the world that we inhabit. And, yet, mysteries persist.
People have debated questions for decades — sometimes centuries. Fortunately, our unfaltering will to uncover the world’s mysteries has brought us closer to some answers than ever before. Here are some mysteries that still keep scientists up at night, and how close they are to solving them.
Dark Matter
What are the spaces beyond the universe? How do stars move within Galaxies? The visible components of the space which are made up of atoms, molecules, etc. take up only 5% mass of the entire universe. (Earth, Planets, Sun, etc). The remaining 95% matter is invisible known as the Dark Matter. Scientists came to the conclusion of this invisible matter due to the galaxy movements and its interaction with the gravitational pull.
Scientists even drew skepticism about there being only one type of gravitational pull due to the enigma of dark matter. If scientists possibly unravel this mystery, they might know whether the universe will continue to expand. But the question arises, how do we know that dark matter exists if it is invisible which makes Dark matter the top and the most explored one in our list of unsolved mysteries of science.
Why is there a monster black hole in the heart of every galaxy?
There are about two trillion galaxies in our Universe and, as far as we know, almost every one contains a central supermassive black hole. They range in size from monsters, weighing almost 50 billion times the mass of the Sun, to the 4.3-million-solar-mass tiddler known as Sagittarius A* in the core of our Milky Way (one solar mass = mass of our Sun). But how they got there is one of the great unsolved mysteries of cosmology.
We know that a stellar black hole forms in a supernova explosion in which the core of a star implodes. But nobody knows how a supermassive black hole forms.
For most of cosmic history, the centres of galaxies have been where a lot of matter is confined in a small volume. It could be the case that supermassive black holes form in a dense star cluster out of stellar black holes which repeatedly merge with each other.
Why is there an arrow of time?
Time moves forward because a property of the universe called "entropy," roughly defined as the level of disorder, only increases, and so there is no way to reverse a rise in entropy after it has occurred. The fact that entropy increases is a matter of logic: There are more disordered arrangements of particles than there are ordered arrangements, and so as things change, they tend to fall into disarray. But the underlying question here is, why was entropy so low in the past? Put differently, why was the universe so ordered at its beginning, when a huge amount of energy was crammed together in a small amount of space?
What happens inside a black hole?
What happens to an object's information if it gets sucked into a black hole? According to the current theories, if you were to drop a cube of iron into a black hole, there would be no way to retrieve any of that information. That's because a black hole's gravity is so strong that its escape velocity is faster than light — and light is the fastest thing there is. However, a branch of science called quantum mechanics says that quantum information can't be destroyed. "If you annihilate this information somehow, something goes haywire," said Robert McNees, an associate professor of physics at Loyola University Chicago.
The Theory of Everything
The theory of everything, it’s perhaps the most popular problem in physics, which has the most number of theoretical physicists trying to solve the problem (directly or indirectly). The aim is to have a theory that links together and explains all physical properties and observations of the universe.
In modern physics, we have Einstein’s explanation of gravity that involves the use of the four dimensions of spacetime called General relativity, this is an explanation by Einstein that works so well that it explains precisely the orbits and motions of all celestial bodies we have ever seen. While Newton’s theory (which General relativity replaced later) was based on simple mass and distance of two objects, and never explained why gravity was experienced, GR actually explained how gravity worked and was far more precise. This theory works perfectly for all large objects in the macro scale. It does not really work at the subatomic scale.To describe the subatomic scale of the universe, the theory of choice is the Standard Model, which successfully explains the other three observed forces of nature, which are electromagnetic, weak and strong forces. The recent (2012) discovery of the Higgs Boson was another confirmation of the veracity of the Standard Model.
How does gravity work?
We all know that gravity from the moon causes tides, Earth’s gravity holds us to the surface, and the sun’s gravity keeps our planet in orbit, but how much do we really understand it? This powerful force is generated from matter, and more massive objects therefore have a greater ability to attract other objects. While scientists do understand a great deal about how gravity acts, they aren’t really sure why it exists. Why are atoms mostly empty space? Why is the force that holds atoms together different from gravity? Is gravity actually a particle? These are answers that we really just can’t answer with our current understand of physics.
Why do we sleep?
While we do know that the human body is regulated by a circadian clock that keeps humans on a sleep/wake cycle, we don’t really know why. Sleep is the time when our bodies repair tissues and perform other maintenance activities, and we spend nearly a third of our lives snoozing. Some other organisms don’t need to sleep at all, so why do we? There are a few different ideas out there, but none seem to solidly answer the question. Some theorize that animals who are able to sleep have evolved the ability to hide from predators, while others who need to remain more alert are able to rest and regenerate in other ways without fully going to sleep. While scientists don’t quite know why we do it, they are starting to learn more about why it is important, and how sleep impacts important things like brain plasticity.
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