It can look like an uphill challenge to try to comprehend the universe around us. We have found many responses to the mysteries in our world: how planets orbit the Sun, why an apple falls from a branch to the ground, and why the sky is blue. The quest to reveal all of the secrets of the cosmos is certain to be filled with difficult challenges, unbelievable problems and a mountain of ingenuity require to overcome them.
Many physicists have at present wrestled with the riddles of existence, but there are many more puzzles to solve. Get ready for the ten extreme unsolved mysteries of physics... the paradoxes that have evaded the most eminent minds the world has ever known.
We cannot observe it and we cannot feel it, but we can test for it, and nobody knows what it is. In spite of this, researchers believe that dark energy makes up about 70% of the cosmos. It was imagined to explain why galaxies do not just drift apart but instead accelerate away from each other. You can think of it as a repulsive gravity that drives matter apart. How it works, though, is still a mystery.
The other "dark" substance in our cosmos. Dark matter, like dark energy, cannot be observed or felt. This elusive substance has some differences to dark energy however; the only way that we have detect it is indirectly. We know that there must be more matter in the cosmos than we can witness because we can measure its gravitational effects, but no one knows precisely what makes up this enigmatic stuff.
It's a wave... it's a particle!
Rays of light have a split personality. They produce interference patterns that are typical of waves. They reflect off surfaces, proposing that they could be a wave or a particle, or both at the same time. They can also be used to release electrons from their shells: something that shows that they are particles. But how does light conclude whether it acts as a particle or a wave?
Time, the onward rally
We only get older, not younger. Trees only get taller; they do not return to acorns. Our Sun only ever utilizes up its fuel, never recurring to a cool ball of hydrogen gas. Time only goes in one direction... but why is it impossible for us to reverse the clocks?
We are living in a hologram
This one confuses the mind. The cosmos, everything we observe and feel and experience, may in fact have two spatial dimensions. Think of a 2D hologram, like the one on the back of a credit card: it can have all of the information of a 3D picture but in only two dimensions. Some researchers have proposed that our universe is like the hologram on your credit cards: space appears like it has three dimensions, but it may turn out that all we are seeing is a projection from a 2D cosmos outside of our perception.
Matter and antimatter
There is a definite inconsistency between the ratios of these two substances. There was thought to be an equal amount of ordinary matter and antimatter – particles with the same mass but opposite charge – in the initial cosmos, but now the universe is dominated with normal matter. Many theories have been thrown around, for example that particle evolution favored one way of producing matter, but nothing conclusive has popped up. The mystery of how matter "won" over antimatter may be exposed in the newly-upgraded Large Hadron Collider at CERN.
The lifetime of the Universe
This mystery, the end of the universe, might not keep you up at night, but it will surely be of concern to beings alive far into the future. This epic event is prophesied to happen in around 10 billion years. Two opposing theories are the Big Crunch and the Big Rip. Neither of these consequences sound terribly fun. The big crunch is the opposite of the Big Bang – all of the pieces of matter in the cosmos will stop accelerating away from each other and start rushing toward each other. A boiling collision of all of the matter in the cosmos follows (and mankind is improbable to survive that). The Big Rip is where all of the pieces of matter in the universe continue to accelerate away from each other, faster and faster till ultimately space-time moves so fast that it rips atoms apart (mankind is also improbable to subsist that one).
These two possibilities are not the only probable conclusions for the universe – sadly it appears improbable that our generation will ever know its fate.
Why cannot we picture four dimensions?
We little humans struggle to imagine a world with four spatial dimensions. Some theories (such as string theory) requires as many as eleven dimensions to be hypothetically likely. If string theory turned out to be correct, we would have to find out how there are six missing dimensions tangled up in our reality. I can feel a headache coming on...
Why does light have a universal speed limit?
c, the speed of light constant, is valued at 3x108 ms-1. But why this figure and not, for example, 4x1020 m/s? Is it a random digit pulled out of a bag of numbers when a new universe blasts into existence? It's at present impossible to know why the speed of light is the speed that it is... all we know is that our universe could not exist without this limit.
Unifying the big and the small
Everything big, like stars and black holes, is made up of small things: particles. Einstein's laws of relativity govern the very big, while quantum mechanics is king in the realm of the very small. But physicists cannot appear to jam the two theories together. The trouble is that gravity just does not seem to work on the nanoscopic scale. And bizarre quantum effects, like quantum tunneling (whereby an atom can "tunnel" over an otherwise impenetrable boundary), cannot be applied to planets or stars. Your eyes would possibly pop if the Moon rapidly "tunneled" through the Earth. It appears barmy that there would be one theory for everything big and another for everything small. Some researchers are trying to tackle this problem, and even making headway, but the missing link is still extremely elusive.
This post was written by Usman Abrar. To contact the writer write to firstname.lastname@example.org. Follow on Facebook