## Simple Understanding Of The Complex Universe Part-7

In the last article, we have understood the concept of a black hole, and it’s applications. In this article, let us know the idea of wormholes.

Wormhole: In simple terms, a wormhole is like a tube connecting two places in space. By travelling through the wormhole, you could travel large distances across space exceptionally faster.

As of now, wormholes are a theoretical concept. If a wormhole is created, you can theoretically travel faster than the speed of light from one point to another in the universe. According to the math, wormholes are very unstable and collapse immediately once they are formed.

Let us try to understand the history of the wormholes.

History of wormholes:

Wormholes were first theorized in 1916, While reviewing another physicist’s solution to the equations in Albert Einstein’s theory of general relativity, Austrian physicist “Ludwig Flamm” realized another solution was possible. He described a “white hole,” a theoretical time reversal of a black hole. A space-time conduit could connect entrances to both black and white holes.

In 1935, “Einstein” and physicist “Nathan Rosen” used the theory of general relativity to develop on the idea, proposing the existence of “bridges” through space-time. These bridges connect two different points in space-time, theoretically creating a shortcut that could reduce travel time and distance. The shortcuts came to be called “Einstein-Rosen bridges”, or wormholes.

Theoretically, a wormhole can be created by creating two black holes opposite to each other. The black holes suck in all the horizons of each other and leave a tunnel to pass through. If a wormhole is ever to be formed, it must have a matter called “exotic matter.”

Exotic matter: These are hypothetical particles and states of matter that have “exotic” physical properties that would violate laws of physics, such as a particle having a negative mass.

Imagine a particle having a negative mass; it will move away from the direction where a force is applied. That is the reason even if a wormhole is created, it collapses as the force acts inwards very fast due to the negative mass effect.

Applications of a wormhole:

• Time travel is possible if we can create a wormhole. According to special relativity, time slows down when we approach the speed of light. But in a wormhole, we can travel faster than the speed of life. By this, the time stops, and we can travel through it.
• If we can create a wormhole, we can make the fastest mode of transport. As wormholes act like a tube of travel between two points, you can travel between them faster than the speed of light.
• By reversing the properties of the wormhole, we can create a controlled black hole and study the properties of the same and uncover the secrets of the universe.

Let us hope that the scientists can create a wormhole and can be used for the betterment of human life.

## Simple Understanding Of The Complex Universe Part-6.

In the last article, we have understood the concept of antimatter and its applications. In this article, let us know the concept of black holes.

Blackhole: In simple terms, we can define blackhole as space which has a powerful gravitational force. So strong that even light can’t escape it. In physics terms, A black hole is a region of spacetime where gravity is so strong that nothing, no particles or even electromagnetic radiation such as light can escape from it. The theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a black hole.

Black holes are formed when dying star implodes itself at the centre and creates a “supernova”. A supernova is a star that increases significantly in brightness because of a catastrophic explosion that expels most of its mass. As even light cant escape black hole, black holes are not visible to the naked eye.

There are two main parts of a black hole, the event horizon and singularity. Let us try to understand them.

1. Event Horizon:  It is the boundary surrounding the region of space of a black hole from which nothing (not even light) can escape.
2. Singularity: In the heart of a black hole is a gravitational singularity, a one-dimensional point which holds a huge mass in an infinitely tiny space. The density and gravity become infinite and spacetime curves infinitely. The laws of physics as we know them to cease to operate.

If we fall inside a black hole, we don’t get sucked in like a vacuum cleaner. If we fall inside, we get stretched vertically and compressed horizontally. We are stretched to an extent where you become hot stram of plasma. As gravity acts like a million times more than the standard gravity, your body becomes a massive massacre. But for the nth zeptosecond you are in the black hole, you can see the universe in fast-forward like looking into the future.

The sun of our solar system cannot be turned into a black hole as it is not massive enough to explode. But hypothetically if it turns, there will be no effect of planets as the gravitational force in the solar system would be the same. But we will freeze to death due to lack of sunlight. Let us understand the history of the black hole.

History Of Black Hole: Albert Einstein first predicted the existence of black holes in 1916, with his general theory of relativity. The term “black hole” was coined many years later in 1967 by American astronomer John Wheeler. After decades of black holes being known only as theoretical objects, the first physical black hole ever discovered was spotted in 1971.

In 2017, using eight telescopes known as “Event Horizon Telescopes,” the first image of the black hole was captured.

Applications Of Blackhole:

1. Black Holes gives us a way of studying abstract concepts like gravity and general relativity, magnetic field and many properties of these concepts.
2. A supermassive black hole is theorized to be at the centre of every galaxy, implying it is necessary for the existence of a galaxy.
3.  It explains the concept of Tidal Forces.
4. It accounts for a significant amount of mass in the universe.
5.  A moving or spinning black hole can hypothetically create a wormhole, a way of transitioning across space faster than light. It is hoped that in the future some means of transport can be founded to help us travel in these portals, which may lay the base for the search of extraterrestrial beings and uncommon minerals and elements.

## SIMPLE UNDERSTANDING OF THE COMPLEX UNIVERSE, Part-3

In the last article, we have understood the concept of quantum physics, and how it explains the laws of the universe. In this article let us learn the theory of relativity which brought a massive revolution in modern physics.

Before that we need to know how and who came with this idea. Albert Einstein came up with the ideas of theory of relativity. One day when he was working as a patent clerk at Bern, finished his work and boarded a tramp car on his way home. He used to finish his work as soon possible so that he can contemplate the truths of the the universe. In his free time, he used to think of different experiments for the better understanding of the universe.

That day, he devised one experiment on that tramp car which changed modern physics forever. While travelling in the tramp car, Einstein saw a clock tower, and he is moving away from it. He imagined what would happen if the tramp car would move with the speed of light? The speed of light is 186,000 miles per second; he realised if he travelled at that speed, the clock’s hands would appear to be completely frozen. At the same time, he knew that back the clock tower the hands would tick along with normal pace. Time has slowed for Einstein.

This thought blew his mind; he concluded that the faster you move in space, the slower you move through time. His work was heavily influenced by two of the great physicists of all time. First, the “laws of motion by” “Sir Isaac Newton” and second by the “laws of electromagnetism” by “James Clerk Maxwell.” According to the laws of motion, velocities are always relative. For example, imagine a train travelling at 50 kilometres per hour. The speed of the train is 50 Kilometers per hour for someone at rest. It is only 30 kilometres per hour if another train is travelling with respect to this train and in same direction with a speed of 20 kilometers per hour.

This is true for the earth, sun, Milky Way galaxy and other galaxies. According to Maxwell, the speed of an electromagnetic wave(in this case light) is constant, regardless of the observer. If we take Newton’s laws into this, there is a clash, according to newton the velocity and speed are relative but the speed of light is constant regardless of the observer. Thus Einstein proposed his “Special Relativity theory” in 1905.

Special Relativity Theory: There are two postulates of special relativity.

1. The laws of physics take the same form in all inertial frames of reference.
2. As measured in any inertial frame of reference, light is always propagated in space with a definite velocity “c” that is independent of the state of motion of the emitting body. Or: the speed of light in free space has the same value “c” in all inertial frames of reference.

The first postulate says that the laws of physics are the same for the person who is in moving in constant velocity or at rest. If we apply any laws of physics the results will be the same. The second postulate is very explanatory.

Mass–energy equivalence: Mass-energy equivalence states that the total mass of a system may change, although the total energy and momentum remain constant. In simple words,  mass can be converted into energy and visa-versa.

E=mc2

Where E = Energy.
M = Mass.
C = Speed of Light.

Applications of special relativity: There are many applications of some of the important ones are GPS (Global Positioning System), Cathode-ray tubes (Old Television screens), modern computer chips and most important of all, by the concept of “Energy – Mass equivalence” was essential for the development of “nuclear fission” and “nuclear fusion” which are used in all nuclear plants.

So we understood the concept of special relativity, now let us understand the concept of general relativity. Before that, we need to understand the back story of the same.

Again back to Einstein and his brilliant imagination. One day he was observing a window washer on a ladder from his office. He imagined what would happen if the washer fell, for most of us it is a horror story which will never end will. But Einstein thought it differently, he imagined himself in the place of the washer while falling. He didn’t imagine what would happen if he hits the ground but imagined what he would experience while falling.

He realised that gravity was the only force acting on him while he was falling and accelerating towards the ground. Without the wind resistance, he would be free in fall, which is no different from being weightless as the ground is not coming up. This is nothing, but he is falling in space where there is zero gravity. He wanted to connect gravity to his theory of relativity through acceleration.

Einstein imagined a room without windows and it has a weighing scale and checked his weight, it would be constant at any point on the earth. Now he imagined the room is in a spaceship, which is moving upward with a speed of 9.8 meters per second which the speed of acceleration due to gravity on earth. Now, what would happen if he stepped on the scale? The weight should be the same as the space ship is accelerating upwards with the same speed that of acceleration due to gravity but this time it is upwards.

Einstein thought about telling the difference between acceleration and gravity, now he imagined shooting a light or laser beam from one point of the room to the other while the spaceship is moving upwards. He saw that the light is bent while moving from one point to another. The size of the light would be lower compared to the projection point. This is because the room is moving upwards with a speed of 9.8 meters per second. The light beam would appear a bit curved downward.

However if you are on earth, you wont see this phenomena. The projection point and the projected points height would be the same. Einstein thought why is this different as it would the equivalence of gravity. The force is constant while it is upwards or downwards. He thought light must bend under the influence of a gravitational field, but how could this be possible as the light always takes the shortest path. May be the shortest point between two points is a curve?

Imagine earth which is spherical in shape, the surface if the earth is never a straight line, it is always a curve. So may be the gravitation causes the curvature of space somehow. He hypothesized may be the straight line is not the shortest path in space, with the presence of mass and energy space somehow becomes curved. This is again different from Newton’s hypothesis in which space and time are fixed. In Newton’s model, gravity acted within space and time.

Einstein’s theory was gravity emerges when there is an interaction between space and time. This is General Relativity in a nutshell.

General Relativity: The central idea of general relativity is that space and time are two aspects of spacetime. Spacetime is curved when there is matter, energy, and momentum resulting in what we perceive as gravity.