NEWS- Magnetic Bubble could act as a saviour for Astronauts

By: Arjit Mishra

Human race is trying it's real best to set foot on Mars and other Exoplanets but apart from all the obstructions one of them is that sending astronauts on long-duration missions is kind of impossible because of the hazardous radiation levels in space.

However a new concept offers some hope on the horizon, this Idea takes advantage of the latest advances in superconducting magnet technology to effectively shield spacecraft—and the astronauts inside—from harmful space radiation.

The researchers behind it have received funding from NASA innovative Advanced concepts (NIAC) program to build a prototype called CREW HaT.

HaT stands for Halbach Torus, which is a circular array of magnets that creates a stronger field on one side while reducing the field on other side, They've came up with a design for lightweight, deployable and mechanically supported magnetic coils activated by a new generation of high temperature superconducting tapes.

This configuration produces an enhanced external magnetic field that diverts cosmic radiation particles, but the most interesting thing is that the geometry being proposed creates a magnetic field outside the spacecraft but not inside, so the astronauts are not exposed. The created magnetic field is directly extended out into space it's not bounded within a chamber or something.

Researchers believe that this design can divert over 50 percent of the biology-damaging cosmic rays and higher energy high-Z ions that are responsible for health complications and deaths of astronauts in space. Moreover They still need to reduce the weight and work on the design to make it more efficient.

"GOD HAS NO INTENTION OF SETTING A LIMIT TO THE EFFORTS OF MAN TO CONQUER SPACE"

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TIME CRYSTAL: A NEW 4-D MATTER

 BY: Arjit Mishra

The act of Modification of theories into facts is ,always in continuation and will continue in future. The biggest prophecies of Theoretical Physics like- Einstein's gravitational waves, Higgs Boson, etc. have came into being by experimentation. Recently Scientists have discovered a new and rare state of matter, which was first theorized in 2012 but the theory was unfortunately rejected.

This new state of matter is often called Time Crystal. The interesting fact is that the Atomic state of this state of matter repeats in space-time, which means Time crystals are 4-dimensional objects. Till now we have only examined 3-D matter but in today's Blog I will describe a 4-D Matter.

What are Time Crystals ?

Before I will explain you the concept of Time Crystals, firstly we should know about crystals :

A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. simple examples are-Diamond and pieces of ice.

if we observe Atomic structures of simple 3-Dimensional crystals, we can say that they repeat their arrangement to some extent in space but Time doesn't effect it's arrangement. which means if we observe a diamond now and observe it again after few hours their would be no change in it's Atomic arrangement.

Now coming to Time Crystals: In case of Time Crystals atoms not only repeat their arrangement in space but also in Time and because of which their shape changes every time on it's own without any force and they always remain in perpetual motion, They can't attain thermal equilibrium state because they are non-equilibrium metals, very much different from simple theory crystals.

How Time Crystals Work ?

Normal Matter: Suppose we have a simple crystal in which atoms repeats their arrangement over space. If we provide some energy from external source then the energy would flow adjacently in the atoms till all the atoms attain thermal equilibrium which is often called Zero point state, In this state heat is equally divided among all the atoms and thus in most of the cases they don't have enough energy to cause motion because of which they stops.

 for understanding this in a more simpler way let us take an example- when we kick a football, it stays in motion for few seconds and eventually stops but football in state of rest can't come to the state of motion on it's own.

Non-Equilibrium Matter: In case of Time Crystals, Atoms in Quantum Entanglement are arranged in repeated patterns. So as the Energy reaches an Entangled particle it's entangled pair came to know about it instantaneously (independent to the distance between them) and before energy actually reaches to the entangled pair, it starts to react because of which all particles come into the state of motion and this reaction exists perpetually that's why the Time Crystals can't attain the state of Thermal Equilibrium and show movement even in their lowest energy state.

 [If you don't know about Quantum Entanglement visit- Theoarmi ].

Idea behind Time Crystals ?

In 2012 noble prize winner Frank Wilczek thought of a crystal which breaks time translation symmetry. Time Translation symmetry says that "Laws of Physics are applied equally in all the places of UNIVERSE and in all the times which have ever existed." Till many years we have believed that symmetry is always same in Laws of nature but eventually we came to know that Deviation occurs in the symmetry of Laws of Nature. Some object breaks this symmetry by staying in their ground state without breaking the laws of physics. Frank thought that if symmetry breaks in the space then it should also break in Time. He imagined a crystal which could break the symmetry in time that's how Time crystal was Discovered but theory of time crystal was approximately same as the theory perpetual motion machines which can work till eternity without any Energy. According to physics laws these machines can't be invented in reality that's why theory of Time Crystal was also rejected. Later on scientists corrected and modified this theory with help of Quantum Entanglement and Non-Equilibrium metals. With the help of two different experiments scientists have made Time crystals in a Lab.

How can they be useful in future ?

Time crystals could be useful in Quantum Computing, Physicists can use these Time crystals to build stable Quantum system which would work efficiently even on higher temperatures. Discovery of Time crystal is just an initiation, what would happen in the future would be amazing!

"You will always have time for what you make time for"

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QUANTUM ENTANGLEMENT AND EPR PARADOX EXPLAINED

BY: Arjit Mishra

Today our whole Scientific Community agree to the fact that the Quantum World is intensely mysterious and weird because in this stuffs don't work according to our thinking. 

when Quantum Theory was new, It  has bothered number of scientists back then which includes Albert Einstein too.

Actually Albert Einstein was not able to swallow the Theory beyond his throat because predictions of Quantum Theory were literally weird. So to prove this Theory wrong, he though described a Thought Experiment with his two colleagues, which he named EPR Paradox. and this thought Experiment birth an unique phenomenon which is still a topic for research due to its weird behaviour. This phenomenon is called Quantum Entanglement. Einstein and his colleagues just created the base of EPR Paradox to defy the concept of Quantum Theory but happened contrary. Actually when Einstein and his colleagues discussed about EPR Paradox ,then there were no required instruments to go for experimentation that's why it has been treated as a Thought Experiment, because of which any conclusion can't be made. 

But after some years when they have required instruments, they Experimented it and found that Einstein and his colleagues were wrong, not the Quantum Theory because the results of the performed experiment were same as predicted by the Quantum Theory.

As Quantum Theory and it's weird predictions were true, It has completely changed our visionary perspective for the REALITY. Today Scientists agree to the fact leaving no room for debate that

the Real Nature of this UNIVERSE can only be explained by the Quantum Theory.

In 1920s Nature of Reality was the biggest Topic of Debate between Einstein and Neil Bohr.
Einstein believed that our reality is always fixed that's why there is no difference in it's format, if we observe it or not. He said Moon is always present at it's position whether we observe it or not, In fact our whole classical physics is based on this notion and we blindly believe that entities present near us that we are observing are present in same nature and position at the time when we are not observing them.but Quantum Theory doesn't agree to this notion and believe in fuzzy nature of Reality.

Neil Bohr believed that In the Quantum World and in absence of observations and measurements our Reality do not exist, In case of Quantum particles till when we don't observe or measure them we can't tell anything about their characteristics because before observation and measurement they are actually not in a well defined form instead they exist in all the possible states of themselves together which we call Superposition state and till this time physical nature of Reality doesn't make sense at all because till then there is no physical form of these Quantum Particles and the Reality form of this time can only be represented by Wave Function which itself describe the superposition state but as we observe and measure these Quantum Particles their wave function collapses and because of this, A single possible state is chosen from all the possible states it could ever have and in the end this state is obtained; After our observation and measurement we only get a single possible state and because of this we come to a conclusion that this state only is the Reality of that Quantum particle but actually amongst all those possible states any one could be obtained and this means it is not fixed that after observation or measurement which possible state would be obtained. thus in the absence of observation and measurement our Reality doesn't makes sense.

The Copenhagen Interpretation is based on this theory which is believed to be true in the Quantum Mechanics.(I will make a separate Blog on this concept later. )

Anyway, Einstein can't swallow Neil Bohr's theory beyond his throat. He thought everything is Real always and doesn't rely on our observation and measurement.About the Weird predictions of Quantum Theory Einstein said that the Quantum Theory is still incomplete and lacks some Local hidden variable which can be used to predict everything accurately so that we don't need the concepts of superposition state and wave function. Einstein with Boris Podolsky and Nathan Rosen designed the base of EPR paradox to prove Neil Bohr's theory wrong, which itself was the good example of Quantum Entanglement. Actually at that time required equipments were not present which could test Neil Bohr's Theory that's why EPR paradox is considered as a Thought Experiment at that time.
In EPR paradox, paradox word is used because in this experiment the information between the two particles is travelling more than the speed of light which is violating the rule of Einstein which states-"Spread of Any information in this UNIVERSE can achieve maximum to the speed of Light ."

Let us now understand Quantum Entanglement :

To understand Quantum Entanglement we should firstly understand these two concepts:-

1- Superposition State: As I have already described, in absence of observation and measurement Quantum particles do not exist in their single possible state instead they exist in their all the possible states.
 for example-

 There is a intrinsic property of subatomic particles like electrons which we call 'spin'.
 [NOTE- don't confuse spin to be something like electrons are spinning on their axis, no please not I will describe spin in later Blogs]

now the electron has two possibilities in aspect of spin, 'up spin' and 'down spin'. According to superposition principle the electron is not present in one of the single possibilities mentioned above, but occur in both possibilities together, means the existence of 'up spin electron' and 'down spin electron' together.

2- Measurement Rule: It states that till when we don't observe Quantum particle it occurs in superposition state but as we observe or measure the Quantum particle it's wave function collapses and in the end a single possible state is obtained which becomes our Reality.

In Quantum Entanglement Entangled particles are used, let us understand what are Entangled particles and how they are formed:

Imagine we have a energetic Photon, and this energy can be converted to mass using Einstein's mass-energy equivalence. for example we can make other different particles using photon but our UNIVERSE has laws which decides how and what would be the nature of these particles, as photon has no electrical charge that's why the electric charges of produced particles must add up to zero.
which means if a photon produce a electron then it should produce a positron to maintain the electrical neutrality. along with this there is a property which is called as conservation of spin-
photons have no spin but electrons and positrons have their spins, it can be 'up' or 'down' and one of them must have 'up' spin and other one must have 'down' spin because then only they add up to zero spin(which correspond to photon) but we can't specify that which one would have which spin. if we take the perspective of superposition state, till when we don't observe and measure them they occur in 'up state' and 'down state' together. now if we talk about Entangled state, it is the state in which two particles are linked in such a way that they exist only in combined state which means without knowing the states of both the particles we can't define the state of a single particle. if you didn't get it yet understand with an example- we have an electron and a positron, there spins could be 'up' or 'down'. which particle have which spin that we don't know. In superposition state it can be represented as: 

here electron and positron are in 'up-down' and 'up-down' spins together. which means without knowing the state of one we can't tell the state of the other and in conclusion we can say that in Entanglement, particles can only be described through joined states.

According to EPR paradox  or Quantum Entanglement if we have two Entangled particles and if we somehow get the state of one particle then we can surely tell the state of other particle irrespective of  their distance. for example- after measuring if we get the spin of one particle to be 'up' then we can tell that other particle would have it's spin 'down' and vice-versa. Quantum Theory explain it through this way- As we have two Entangled particles, there properties are linked in such a way that both can exist only in combined state. Before measuring both particles are present in superposition state, which means electron and positron have their spins 'up-down','up-down' together. it can be represented as:

but as we measure any one of them, their wave function collapses and amongst their two possible states only one would be selected .

if we get spin of first particle to be 'up' then second one would have 'down' spin.

or if we get spin of first particle to be 'down' then second one would have 'up' spin.

As Entangled particles exist in combined state only, it doesn't makes sense that these two particles are kept at which distance from one-another. the effect is instantaneous and is independent of distance.
which means if we keep one particle in first end of the UNIVERSE and other one in the second end of the UNIVERSE, then also spin state observed in the first particle changes the spin of other particle and would be instantaneous. As the state of Entangled particles depend on the measurement and observance of one of the particle present in Entangled pair, it can be seen that these particles inform their states to each other with speed more than Light. but Einstein's special theory of Relativity states that-"Spread of Any information in this UNIVERSE can achieve maximum to the speed of Light ."
then how it is possible that Entangled particles present in two different ends of this UNIVERSE effect each other instantaneously because if the exchange of information is taking place with the speed of light then also information should take much Time that's why Einstein called it a paradox.
Einstein agree to the fact that if two particles are away from each other and if we know the state of one particle, state of other one could be found but he didn't agreed that information between them can travel with the speed more than the speed of light. He believed if we have local hidden variables and if we somehow able to  know the state of one particle then state of other particle could be obtained at that time only, information doesn't need to travel with the speed more than light.

Quantum Entanglement was firstly experimented by John Steward Bell and this experiment has proved the Quantum Entanglement Theory to be true, and it has been tested many times till now.
But it is still a mystery for us that two Entangled particles create which type of medium between themselves that enable them to share the information with the speed more than Light. 

“Life is a field of cosmic consciousness, expressing itself in million ways in space-time through quantum entanglement.”

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WHAT IS GRAVITATIONAL LENSING ?

BY: Arjit Mishra

Infinitely dispersed this Universe has number of mysteries, to remove the counts from these mysteries we created a powerful Telescope renowned as Hubble Telescope, which not only just enable us to observe distant and complicated Astronomical events but also we can peep into Past and observe the Past time of our Universe.

It is not completely true to say that only we(Humans) have to make efforts and build powerful machines for solving the mysteries of this Universe, sometimes nature also help us to do so. Gravitational Lensing is one amongst the natural phenomenons which stands for the above given fact.

The concept of Gravitational Lensing completely depend upon Properties of Space. It help us to see those Galaxies, Quasars and Stars which are billion of Light years away from us but we can't observe them directly. It is Gravitational Lensing which reveal the concept of Dark Energy.
This Blog will reveal the basic understanding behind Gravitational Lensing along with How Dark Matter was discovered with the help of Gravitational Lensing.

"what is Gravitational Lensing? and how does it work?" before answering these questions I would like to tell you the concept of lenses in normal Life:

Atually Lenses have the tendency to bend the path of Light.In case we have a Convex lens on which a beam of Light is focused it will converge the beam of light at a particular point.but if we have a Concave lens it will diverge the beam of light.

However Gravitational Lensing works similar to a Magnifying Glass. Let us understand how a simple Magnifying glass works:

We could see anything around us only if it's Light is reaching our EYE.When we see an object with our eyes it appears of same size as it is actually but if we see it through a magnifying glass it appears bigger in size.It is because beam of Light coming from the object got converged by the convex lens present in the magnifying glass and if we extend this converged path of light in it's backward direction we would be able to see that object apparently Bigger than it's original size; this is because our human brain can only perceive Light as a straight line.

Now we should move on to Gravitational Lensing Phenomenon:

In 1915 Albert Einstein proposed his general theory of Relativity which truly define gravitational force. He proposed that every mass warps the space-time continuum, and this warping phenomenon shows direct proportionality to the mass of an object. which means higher mass object would distort space-time more as compare to smaller one and because of this smaller mass object feel attraction towards the curve formed by higher mass object bcoz of the shape of space-time at that position, and this attraction is so called Gravitational Force.

We know that Light always travel in a straight in vacuum, but if Einstein's general theory of Relativity was true then it is obvious that higher mass objects like: Stars, galaxies, clusters, etc. would also warp the space-time according to their masses.which means when light passes near to these objects,it also changes it's original path because of shape of space-time at that position indicating to a fact that Gravity will act as a Lens similar to a Magnifying Glass, if this theory is true then we should get a natural Magnifying Glass witch would magnify the far present Galaxies, clusters, etc. along with we would be able to observe those stars, quasars, etc. which are hidden behind another big galaxies.but these are only theoretical considerations therefore there was need for experimental verification.

It was the year of 1919, when Eddington decided to prove this theory. He observed sun in Total Solar Eclipse through Telescope at that time a star was present behind the sun which we can't observe as sun was present just before it resisting it's vision. But if Einstein was right and sun warps space-time due to it's mass then due to Gravitational Lensing phenomenon we can observe that star, but you won't believe that Predictions of EINSTEIN'S theory were true and Eddington observed that star.
Originally light from that star shouldn't get to Earth by any means but as sun has bend the space-time by some extent so when light from that star passes through the sun it also gets bended by some extent and due to this virtual position of star changes and we can observe the star (hereby we can't see the original position of star but its apparent position).

TYPES OF GRAVITATIONAL LENSING:

Strong Lensing: This occurs when Gravitational lens is powerful or more specifically the light source behind it is situated very close it. For example- if a galaxy is present behind the galaxy cluster which is situated very close to galaxy cluster then the Galaxy cluster present in front of us act as a  strong lens and the galaxy present behind it appears bigger in size as compare to it's original size as similar to magnifying glass.  As I have already said we can observe an object only if it's light is reaching us.  The light of hidden galaxy takes different paths to reach us due to strong lensing, therefore we can observe multiple images of same galaxy and if position of galaxy somehow changes the positions of multiple images though changes because these multiple images are of same galaxy but it can happen that all images don't change their positions at a same TIME because Light has taken different paths to reach us more specifically the image formed by short path taken by light changes first as compare to images formed by other paths.

Strong Lensing reveals one more wonderful phenomenon called Einstein Ring, when source of Light, observer and lens are present in a same line then light coming from source is uniformly bended by the lens which results a formation of bright light ring which we call Einstein Ring.

Weak Gravitational Lensing: We observe weak gravitational lensing when gravitational lens is not much powerful to propose multiple images of source or Einstein Ring. In this case source appears to be extra streched or magnified. If we know the size and shape of source then we can easily discover the properties of gravitational lens by calculating how much the light bend from it's original path.
Generally we don't know about shape and size of source but we know about their average properties which can be used. for example if we have images of 1000 galaxies and all are of spiral shape then we can say that far present this galaxy is of spiral shape. by using weak Gravitational lensing mainly we discover the properties of those galaxies and clusters which are working as weak gravitational lens.

Micro Lensing: This is totally different from strong and weak gravitational lensing because in this case gravitational lens is much smaller. In strong and weak gravitational lensing we observed that gravitational lens are either galaxy clusters or galaxy. but in micro lensing the work of gravitational lens is done by stars or exoplanets, by this type of lensing we can discover those far away planets or stars whose emitted light turns dim while reaching to us but with help of micro lensing this dim light turns out to be shining for some time let us know how?

As we know that gravity bends the light and lead to the formation of gravitational lens. micro lensing occurs when gravity of a star or planet focuses the light coming from the far away planet or star such that those far away star or planets appears to be shining for some time.

Let us now understand how Dark Matter was Discovered with the help of Gravitational Lensing:

NOTE: About 23% of our Universe is composed of Dark Matter, It is not alike our ordinary Matter and we can't see it but it exists.(I will make a separate blog about Dark Matter and Dark Energy )

We know that Gravitational Lensing takes pace when a mass comes between us and a Light source. for example a Galaxy cluster; it acts as a lens which results distorted magnified or multiple images of that Light source. Imagine the light of hidden galaxy needs to pass through galaxy cluster before reaching us which works as a gravitational lens. The amount of Light we have received can be used to calculate the mass of that galaxy cluster (whiz acting as lens) with the help of computer simulation.
As we know that how Gravity works,we prepare the same gravitational lensing effect on computer and enter the data of received Light, Now we enter the observed mass of galaxy cluster(causing gravitational lensing) and see if we get the amount of light on computer same as we get in real life but surprisingly we obtain that original mass of Galaxy Cluster is not sufficient to bend the Light to an extent same as an extent Light has reached us. In fact the original mass of galaxy cluster is only 10% of that mass which actually done the work of Gravitational lens. It means in computer simulation to make the same gravitational lensing effect we require the mass of 9 other galaxy clusters, this missing mass can be of faint baryonic objects like- Black Holes, Interstellar objects, dust and planets.but after observing many galaxies closely we discover that the masses of these objects too are not same as missing masses. which means it is true that In this Universe something is there which we can't see but it has it's mass and is responsible for Gravitational Lensing but question is what is this new entity and where it exists. After further studies we concluded that it is present everywhere in this Universe and as we can't see it we call it as Dark Matter, it do not interact with Light and therefore is not visible.

  "WE HAVE QUESTIONS BUT DARKNESS HAS ANSWERS TO THEM"

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WHAT IS SPACE-TIME ?

BY: Arjit Mishra

 Time we can't see it, can't hear it, but we can feel it or more specifically we can observe it.
                                        

 What is it ? is it somehow related to Space ?

Before Einstein Scientists used to believe that space and time both exist independently; Any change in Space doesn't effect Time. According to Newton "Time is Absolute" means in every place and every condition it remains same.
But Einstein has it's own definition of Time, He believed that Space and Time are connected to each other and do not exist independently. He defines Time to be Relative instead of Absolute, means it is never same for everyone, it passes differently for different conditions. In the relativistic context we can't separate Space and Time.

Moreover speed of propagation of time depends upon object's velocity and it's Gravitational Field.
If my Gravitational field and velocity is different from your's then Time will not be same for me and you.
An Increase in velocity and Gravity will decrease the speed of time propagation.
                             
                                     Let us understand this with the help of an Example :

As Saturn is bigger than Earth then it's Gravity is also bigger than Earth and because of this Time propagation speed will be less on Saturn as compare to that of Earth.
If a Human/Animal somehow able to live on Saturn then he/she/it would live longer than a person/Animal of same age on earth because Time would pass differently for both of them.

Similarly If we are travelling in a spaceship whose velocity is very high then time propagation speed would be slow as compare to outer world. This clearly indicate that Space and time are interconnected. The concept of Time dilation  and Length contraction is very amazing but I would talk about them on my later blogs.

According to Einstein speed of Light is fixed for any inertial frame. As we tend towards the speed of Light, Time propagation speed tends to Zero. Specifically at the speed of Light Time completely stops. To explain the events happening in space and time a Mathematical model is there which we call "Space Time Continuum".

            Before understanding Space-Time we have to understand Space and Time separately :

Everything present around us is a part of Space. To define the position of object in space we take the help of 3-D Graph which has X, Y and Z axis which depict the length, width and height/depth of an object and makes up the 3-Dimensional object.

While in the case of Time it would be difficult for us to define it, but we know that it always moves in one direction that's why we can say that it is our 4th Dimension.

If we combine the space and time then we have presented with 4-Dimensional Space-Time.

as space-time is 4-Dimensional and unfortunately we can't visualize 4-D , but we can visualize it through a 2-Dimensional Graph :

Here X axis defines the space and Y axis defines Time, since Space and Time are connected to each other Anything that moves in Space It also moves in Time.

Physicists observe this world frame by frame Let us know how ?

When we throw a stone into pond we can clearly observe the formation of ripples in it, This is a very common Event that we have observed at least once in a lifetime.

Now let us observe it frame by frame :

When we throw a stone instantly nothing happens but after 1 second one ripple is formed, after 2 seconds two ripples are formed and after 3 seconds formation of three ripples can be observed.

When we see it with full concentration a cone can be observed, Basically this cone is the Locus of light through Space-Time, If we reverse the direction of time then we could obtain the opposite cone which describes the events in past. This cone is specifically called as Light Cone. 

EINSTEIN SAID :

"For us Physicists, the separation between past, present and future is only an illusion, although a convincing one"

Which means past, present and future always exist, propagation of Time is just an Illusion.

A question must be arising in your mind that "why the world seems to moving ?" 

The answer this question is very philosophical, answer totally depends upon principle of video. when we play a video it seems to be moving but actually it is the combination of sequential images slide showed in such a way that the time interval between any two sequential images is very less. but actually there are number of images/Frames at a same time.

Now what is the Advantage of Space-Time Graph ?

Actually with the help of space-time graph we could determine the position and conditions of various celestial bodies and even Universe itself by drawing Bigger and Smaller graphs appropriately.

"Our virtues and our failures are inseparable, like force and matter. When they separate, man is no more."

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WHAT ARE GRAVITATIONAL WAVES? | LIGO AND IT'S WORKING?

In this mystical universe there are some entities which we can observe and understand, but beyond this fact some entities are also there which we could not observe and understand but yet they exist and can be predicted through mathematical equations.

From this undefined amount of treasury I present you the concept of Gravitational Waves :

In 1916 Albert Einstein first predicted the gravitational waves on the basis of his General Relativity.

On 14 september 2015 LIGO detected the Presence of gravitational waves which were radiated by merging of two black holes situated Billions of Light years away from Earth.

This discovery has created revolution in the history of science or more specifically provided another Pillar to Modern physics.

In 1915 Einstein published his general relativity in which he talked about 4-dimensional space-time concept which completely changed the meaning of Gravity. According to him every type of mass Distorts the space-time fabric.

If an object has huge mass It will distort the space-time fabric more and small mass object cause less distortion and this results to attraction of low mass objects towards huge mass objects; this attraction is what we call GRAVITY.

If that huge mass object start moving from its place, It produces ripples(disturbance) in space-time and this disturbance propagate around the UNIVERSE, which we call Gravitational Waves.

Above Example was just introduction. Let us know how Gravitational Waves are actually formed

When Two Neutron stars or black holes are nearby; they firstly revolve around each other and then merges to form single entity.

From the very moment they start revolving around each other repels also start forming in space-time and when they merges to form single entity, a huge amount of energy is released.

NOTE : Gravitational waves are created by two ways -

1. Merging of two massive objects.
2. Motion of a massive object.

These Gravitational waves travel around UNIVERSE at the speed if LIGHT.

Let us know how Gravitational waves were detected :

In 1974 two Astronomers discovered an Binary Pulsar  in which extremely dense and heavy stars were revolving around each other and this was the perfect system to test the theory of Gravitational waves.

After observing till 40 years It was found that both the stars were really attracting each other. Thus Einstein was correct and it means they have also created Gravitational waves bit till 2015 we were not able to detect them.

On the day of 14 september 2015, LIGO detected the distortion in space time field which was caused by merging of two Black holes situated BILLIONS of light years away from Earth(as mentioned earlier). After then we have detected them TWICE.

FACT : As Gravitational waves are ripples produced in space-time. If any source of  Gravitational waves is present near Earth we would have died years ago.

But as they emerge from very very distant source, before reaching earth their effect is very small that it effect earth as same as it's effect on 1000th part of nucleus present in an ATOM. That's why we can't feel this Effect.

WHAT IS LIGO AND HOW DOES IT WORKS  ?

LIGO : It is the Biggest Gravitational waves observatory in the world. In Technical terms it work as same as INTERFEROMETERS.

WORKING : From the central building a laser beam is fired which at base splits into two long perpendicular tubes and these tubes have same length and at the end of them a mirror is placed. when laser beam meets at base after reflecting from the mirrors. The light waves are aligned in such a manner that they cancel out each other which causes no detection at the Photo Detector(placed in central Building). Normally LIGO don't detect anything but when Gravitational waves arrives the earth, It distorts the space and because of that Length of both perpendicular tubes alters for some time.

Sometimes 1st tube gets expanded and 2nd one gets contracted and vice-versa, This happens till Gravitational waves completely passes the earth.

Instruments of LIGO are so powerful and accurate that if 1000th part of proton get effected they could detect it. Because of this the alignments of light waves are not same as before and they can't completely gets cancel out and thus same light reaches to photo detectors and the intensity of  light depends upon difference caused in the length of tubes.Measurement of this intensity provides measurement of Gravitational Waves.

NOTE : LIGO can only detect the Gravitational waves of massive events like merging of black holes or big bang itself.

Gravitational waves not only help us to understand gravity but also to understand the behaviour of unknown entities like WHITE HOLES, WORM HOLES, etc.                    

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