It is a tough task for everyone to understand the universe in which we live. Till date, many mysteries have been found in our world starting from why the sky is blue to why an apple falls down to the ground instead of going up or left or right. The hunt to reveal all the secrets of the universe is sworn to be filled with unimaginable problems, difficult challenges and a mountain of ingenuity needed to overcome them. Physics is all about probing the most fundamental mysteries in nature, so it’s no surprise that physicists have some very basic questions about the universe in their mind. There are many unsolved mysteries in physics.

Here are the five biggest unanswered questions in physics,

1. All about Dark Energy:

Dark energy is something that we cannot feel and we cannot see but it can be tested and the most astonishing thing is nobody knows what it is. Scientists have known for almost a century that the universe is expanding, with all of the galaxies flying apart from each other instead of just drifting apart. As per the assumptions, dark energy is a repulsive gravity that pushes matter apart and dark energy makes up around 70% of the universe. However, it’s working and existence is still a mystery.

2. Is light a wave or a particle:

Light can be described as an electromagnetic wave. A changing electric field creates a changing magnetic field. The changing magnetic field then creates a changing electric field and there you have light. Hence, light can be a wave.  But, When light is emitted and absorbed or in general interaction with matter, it behaves like it is made up of photons which are quanta of light energy. Photons have all the properties of particles except rest mass. We know that in quantum mechanics, particles are represented by their representative wave functions. These wave functions contain all information of the particles. Hence, light is a particle. The mystery is yet to be solved.

3. Why is gravity so weird?

Gravity is a mysterious force that makes everything falls down towards the Earth. Or we can say that Gravity also called gravitation, in mechanics is the universal force of attraction acting between all matters. It is always believed that gravity is the weakest of the four fundamental forces such as the strong nuclear force, the weak nuclear force and electromagnetism. Just imagine how much power rockets have to generate to escape the Earth’s gravitational pull but we can consider it another way. We can probably jump a few feet into the air. For a second, we have been able to overcome the gravitational pull of a huge planet. Or, what about the fridge magnet? The magnetism holding it to the fridge door is greater than the pull of gravity acting on it. Not a very strong force, really, then. But, why? It is thought that, at the moment of the Big Bang, all four were merged but after an unimaginable short time, gravitation became separated from the other three and the reasons are unknown till date.

4. Why is it difficult to imagine four dimensions?

We humans struggle to visualize a world with four spatial dimensions. Some theories need as many as eleven dimensions to be hypothetically possible. If string theory turned out to be correct, we would have to figure out how there are six missing dimensions tangled up in our reality. This is so complex to understand isn’t it?

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