Launch of PSLV-C45/EMISAT Mission (ISRO) on April 1, 2019 at 9.30 hours (IST) from Sriharikota, India

The Indian Space Research Organization (ISRO) is all set to launch the Polar Satellite Launch vehicle (PSLV) C45 on 1st April, 2019. The launch will take place from the rocket port at Sriharikota, Andhra Pradesh at 9.30 hours. The event will be live telecasted on Doordarshan and webcasted on the ISRO website from 9.00 hours. This mission from the Indian space agency is going to be the first of its nature because the satellites is going to be placed in three different orbits.

The PSLV-C45 rocket is going to carry a total of 29 satellites in it. Out of these there are 28 international satellites and 1 indian satellite. Out of the 28 international satellites 2 are from Lithuania, 1 each from Switzerland and Spain and 24 from United States. The most important satellite that the rocket will carry is india's electronic intelligence satellite (EMISAT), which weighs around 436 kgs. This satellite will help the Defence Research and Development Organization (DRDO) in research and development.

The triple orbit launch will take around 3 hours and weather conditions does play a big role int this. In fact, the launch was supposed to take place on 21st March, 2019 which was postponed to 1st April, 2019. The countdown has already begun. Its going to be yet another achievement for the Indian space agency. Watch it live on Doordarshan or ISRO website from 9 hours onwards.

Rocket Launch

By Prabir Rudra

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LIGO will come back online on 1st April, 2019 after a big upgrade

LIGO (Laser Interferometer Gravitational wave observatory) is a facility that was responsible for the first Gravitational wave detection back in February, 2016. Gravitational waves are ripples in the fabric of space-time caused by highly explosive events like black hole mergers, collision of stellar remnants (white dwarfs, neutron stars, etc.), supernova, etc. Einstein predicted this almost 100 years back as a possible test of his theory of General Relativity. The 2017 Nobel prize in Physics went to three distinguished scientists Kip Thorne, Barry Barish and Rainer Weiss for their ground breaking work in designing and setting up LIGO. 

There are two set-ups one located at Hanford, Washington and the other at Livingstone, Louisiana. Last year both the facilities of LIGO was taken down so that its detectors could undergo some serious hardware upgrades. 

The set-ups basically consists of two perpendicular concrete pipes joined in the shape of a giant 'L' each extending to around two miles (3.2 kilometres). Inside these these pipes two powerful Laser beams are bounced off a series of mirrors. Since the two pipes are of the same length the two beams remain in phase with each other. But whenever a gravitational wave passes through the facility it extends one of the pipes and contracts the other one thus creating a difference in length. This distortion in space gets the beams off balance and they become out of phase. This is what is measured with extreme precision. 

Till date 11 such events have been recorded by the facilities. Out of these, 10 events were due to merging of black holes and 1 event arose from the collision of two neutron stars.

LIGO has recently announced that these upgrades are almost complete and the observatories will be up and working from 1st April, 2019. We hope that better technology will give us better observations and we will soon make serious breakthrough into gravitational wave astronomy.

LIGO facility

For more on LIGO visit  https://www.ligo.caltech.edu/




Image courtesy:  https://www.ligo.caltech.edu/images

By Prabir Rudra

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Live webcast of the super worm moon and the vernal Equinox

Slooh.com is an online observatory that is going to live webcast the Super worm moon and the vernal equinox today (20th March, 2019) at 2 p.m. EDT (1800 GMT) . The observations will be conducted via the Canary island telescopes. Two Slooh Astronomers Paul Cox and Dr. Paige Godfrey will discuss the dynamics involved between Earth and Sun during an Equinox. You can watch it directly at  https://www.slooh.com/shows/event-details/621

By Prabir Rudra

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Relativity for All Contd.!! (The General theory of Relativity)

On the 140^th birth anniversary of Albert Einstein it is our great pleasure to revisit one of his greatest masterpiece, the General theory of Relativity (GR) (arguably the best theory of Einstein). Today we discuss GR in his memory and ponder over the extraordinary genius of the man who redefined Physics in the 20^th century.

Albert Einstein

Background

After his miraculous year in 1905, when he laid the foundation of 4 groundbreaking theories of nature (Photoelectric effect, Brownian motion, special theory of relativity and “the world’s most famous equation, E= mc2”), Einstein came to the limelight. 

World’s most famous equation

From a patent clerk in Bern, Switzerland Einstein became a lecturer in the University of Bern in 1908. The following year he was appointed as an associate professor of theoretical physics in the university of Zurich. Einstein became a full professor in the Charles-Ferdinand university in Prague in April, 1911. In 1912 he returned to Zurich as a professor of theoretical physics in ETH, Zurich. He decided to move to Germany and on 1^st April, 1914, he joined the Berlin University.

During all these switch overs from one institute to the other Einstein kept nourishing his original idea of generalizing the theory of relativity that he proposed back in 1905. It was as situation of crisis to humanity. First world war was about to break out. But all these seemed to have minimal effect on the genius. A sense of incompleteness kept haunting him through days and nights.

General theory of Relativity

                                       The Problem 

If we recall our last discussion of Special theory of Relativity we will note that the theory was valid only for inertial (non-accelerated) frames of references. But in reality almost all frames are accelerated . A moving car needs to accelerate or de-accelerate. Similarly a cyclist has to use brakes while cycling. A football rolling on the ground de-accelerates due to friction. All these are non-inertial (accelerated) frames of references where special theory of relativity is not applicable. 

So we need a general theory of relativity that will be applicable to all frames of references (both inertial and non-inertial frames).

Why a theory of Gravity?

In the attempt to generalize his theory of relativity, Einstein knew that he has to incorporate acceleration in his theory. Now acceleration comes from force. In a great insight Einstein understood two things which he stated as the Principle of Equivalence.

1)  The equivalence of inertial and gravitational mass.    

2)  The gravitational force experienced locally while standing on a massive body like Earth is the same as the pseudo force experienced by an observer in a non-inertial frame of reference.

He had the feeling that this can really be a theory of gravity. He started to consider the problem of gravity seriously. He consulted Max Planck (who laid the foundations of Quantum mechanics in 1900) and told him about his intentions to work out the gravity problem. 

The legend says that Planck told him “There are two possibilities: (1) The gravity problem is so difficult that probably you will never succeed.  (2) Even if you are able to find a solution to the problem nobody will believe you.”

Max Planck

The weak link of the prevailing Newton’s theory of Gravitation

The first comprehensive theory of gravitation was stated by Isaac Newton in the 17^th century. It stated that:

Any two masses separated by a certain distance will attract each other by a force directly proportional to the product of the masses and inversely proportional to the square of the distance between them.

The theory seemed to be fine at that time with no flaws and was universally accepted. Newton became the God and very few people had the guts to question his intellect. Moreover the problem of gravity was very difficult to address and so only a few showed any further interest and believed in Newton.

Isaac Newton

But some natural questions arise:

What is the source or the origin of the force?

What is creating it?

Why is it present at all?

Newton was silent to these questions. He did not have any logical answer to it. 

The Theory that answered the above questions

Einstein’s theory of General Relativity is a geometric theory of gravitation that answered the prevailing questions of the critics.

Einstein argued that space-time (space and time together) is like a stretched fabric.  Now when we put a mass on such a fabric naturally it will create a curvature around itself. This is warping (curving, bending or twisting) of space-time that gives rise to a gravity well around the mass. Now when a second mass comes within the curvature quite naturally it moves towards the first body due to the gravity well produced. 

Curvature in space-time

Einstein argued this is what gravitation is!! It is not a force at all as Newton had proposed almost 250 years back. It is a phenomenon that is created by the geometry or curvature of the space-time.

Greater the mass greater the curvature on the space-time fabric

What a masterstroke indeed!! What a beautiful insight!! The common mind can only bewilder and get lost in its aura!! Such was the extraordinary genius of a curious mind.   

The Race to Glory

Einstein had developed the physics of the theory back in 1912, but he did not have any clue about the Mathematics. He needed sufficient knowledge about the geometry of curved space-time (Non-Euclidean geometry) before he could proceed towards developing any meaningful mathematics of the theory. 

Einstein was far from being an expert in such a geometry. But one man by the name of David Hilbert was. He was a mathematical giant of that era. Hilbert took up the problem and started developing the mathematics, which came as a terror to Einstein. His theory was in danger of being credited to somebody else. He had to act and act fast.

David Hilbert

Einstein’s friend Marcel Grossmann (a great mathematician) came to his rescue. With his help Einstein learnt the concepts of Riemannian (Non-Euclidean) geometry and started developing the mathematics of his theory. Hilbert on the other hand continued his effort silently but swiftly. 

As the race to glory became more and more intense the scientific community watched the battle of the two scientific giants (one physicist, the other mathematician) and waited eagerly for a result.

By the grace of God, it so happened that both these great minds reached their destination independently and almost simultaneously. By 1915 both had their own versions of the mathematics of GR ready. On careful scrutiny it was found that both were correct.

Hilbert accepted that the contributions to the theory was far more loaded in favour of Einstein and the theory of general relativity must go by the name of Einstein. This ended all confusions if at all there was any. Finally in 1916, Einstein published his theory of general relativity in the Annals of Physics.

It is difficult to contemplate the feelings of the great man. During his quest, at some point he must have felt that he was losing the battle. After all Hilbert was a great mathematician and matching him was a herculean task. Therefore after the publication, it could have felt like winning a battle once thought to be lost. But it should be remembered that the physical basis of the theory was solely laid by Einstein and probably that’s enough to retain the credit. 

The Equations of General Relativity

This is a relation between mass and spacetime geometry.

Equation of GR

The Reaction from the scientific community

Accepting this theory was not at all easy for the scientific community. The theory will shake the very foundations of physics. Shock-waves were abundant and far reaching. Scientists had many years of scientific career jeopardized. Isaac Newton’s theory of gravitation was in danger. So it happened as Max Planck had predicted some years back. Everybody demanded a proof for the theory.

The radical nature of the theory was criticized by many great minds. Some even thought that GR is not a theory of physics, but the whims and fantasies of Einstein, who is living in a fantasy world.

Experimental physicists like Philipp Lenard (Nobel Laureate, 1905) went into direct confrontations with Einstein and mocked him publicly. He said that physics is a subject of experiments and observations. We believe what we see. There is no place for dreamers like Einstein in the scientific community. Science got really ugly!!

Einstein retaliated but he understood that he had to give a proof to save his theory from being demolished by the critics (specially nazi).

The Proof of General Relativity

The paper was published. The theory was complete. But it didn’t matter to anybody because nobody believed it. Now the genius of Einstein faced a bigger challenge. How will he provide a proof for the theory for which he fought for over a decade. Moreover he was not an expert in experimentation at all. It was an uphill task for him.

But again his extraordinary genius came out with an extraordinary idea. He proposed the bending of starlight around the solar limb (gravitational lensing) as a possible proof for general relativity. 

He argued that the light from the distant stars that pass by the sun before reaching us on Earth will bend while their journey near the sun. The sun being a massive mass will create a huge curvature in the space-time around it. The starlight while passing by the sun will follow this curvature and get bent. As a result multiple images of the star will be formed in the sky. This is in complete compliance with general relativity.

So if Einstein’s theory is correct starlight will bend around the sun and if it is not then the light will pass unaffected. Einstein requested the astronomers all over the world to go and check it.

Many astronomers including Arthur Eddington, a renowned British astronomer took up the challenge. Watching the faint starlight in the presence of powerful sunlight was always going to be difficult. So they chose total solar eclipse for their observations.

In 1919, Eddington’s observations of a total solar eclipse provided concrete proofs in favour of Einstein’s general theory of relativity. 

A British proof to a German theory provided a thrust towards world peace in the post first world war era. Einstein dreamt of a peaceful world without any wars. Even his greatest scientific theory advocated his humane feelings.

In 1921, Einstein was awarded the Nobel prize, not for his general theory of relativity, but for his discovery of the photoelectric effect (may be to his disappointment).

General theory of relativity has been termed as ‘the most beautiful theory of physics’ ever. Till date it remains arguably the best theory of nature not to win a Nobel prize.

I am not a genius. I am just curious...I ask many questions and when the answer is simple, then God is answering.     

         --Albert Einstein.

By Prabir Rudra

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Relativity for All !!! (The Special theory of Relativity)

We are fast approaching the birthday of Albert Einstein on 14th March, the most celebrated physicist of the 20^th century. Although he was awarded the Nobel prize for the discovery of Photoelectric effect (a pivotal step towards the development of the Quantum mechanics), yet his best scientific work considered by many scientists is the theory of Relativity. Here we revisit the theory in simple terms. So sit back and contemplate the genius of the man and enjoy the beauty of his masterpiece.

Albert Einstein

Background

In 1905, while working in the capacity of a clerk in a patent office in Bern, Switzerland, Einstein had an insight that was going to change the path of science forever. This year is called Einstein’s miraculous year (annus mirabilis) during which he published four ground breaking research papers in the prestigious journal Annalen der Physik (Annals of Physics). Special theory of Relativity was one of them.

Einstein's paper on Relativity in Annals of Physics

Special Theory of Relativity

Einstein always thought that Newtonian mechanics was not enough to reconcile the laws of classical mechanics with the then newly developed Electromagnetism. He developed Special theory of Relativity to address this issue. His fascination with light from his early childhood played a big role in the development of the theory.

Some technical details

The Problem

Newtonian mechanics used the Galilean transformation for the change of reference frames. Due to this the speed of light (c) varied with the transformation of frames of references. This was the weak link which created doubt in Einstein’s mind since he always thought light to be an universal entity which should be invariant to transformation of frames of reference.  So we needed a transformation that will keep the speed of light invariant with the transformation of frames of reference.

Moreover at the turn of the 19^th century Michelson-Morley experiments showed that the speed of light is an universal constant and cannot vary under any circumstance. Keeping these in mind Einstein stated the postulates of special theory of relativity.

Postulate 1:  Speed of light is an universal constant and it is the universal speed limit.

Postulate 2:  All the laws of nature remain invariant under transformation of reference frames (inertial or non-accelerated systems).

Using these, Einstein went on to derive Lorentz transformation that became an alternative for the unacceptable Galilean transformation of Newtonian mechanics.

Note: The basic idea behind the transformation was to preserve the constancy of the speed of light with the transformations of reference frames.

However from the mathematics of the theory it is seen that a deviation from the Newtonian mechanics is obtained only when the speed of a particle is comparable to the speed of light. For low speed particles special theory of relativity coincides with Newtonian mechanics.

It must also be noted that special theory of relativity is only valid for inertial (non-accelerated) frames of reference.

Consequences of the Theory

The consequences of the theory are numerous and far reaching. Here we discuss two important consequences:

       

        1.  Length Contraction

  2.  Time Dilation

Length Contraction

A body travelling with a speed comparable to the speed of light will have its length shortened by a certain amount determined from the Lorentz transformations. This phenomenon is known as length contraction.

An Example: 

Suppose there is a spaceship moving at a speed 0.8c (say) i.e. at 80% of the speed of light  which is close to the speed of light. There is a rod of length 100cm (say) inside the spaceship. For the astronaut on board everything will seem to be normal and the length of the rod will be 100cm.

But consider a stationary observer outside the spaceship. For him the observed length of the rod inside the spaceship thus moving with it will not be the actual length, but a length shorter than it. The length of the rod observed by the observer outside the spaceship will be 60cm.

Thus 100 cm for the astronaut inside a spaceship moving with a speed of 0.8 times the speed of light is equivalent to 60cm for us on Earth. For us the length seems to have shortened compared to the actual length. Hence length decreases as the speed approaches the speed of light. That’s Length contraction for you.

Time Dilation

Time for an observer stationed inside a body travelling with a speed comparable to the speed of light will run slower compared to the time for a stationary observer outside the body as observed by the latter. This is the phenomenon of time dilation.

An Example: 

Suppose a spaceship is moving at a speed of 0.6c (say) i.e. at 60% of the speed of light which is comparable to the speed of light. Now suppose a particular event occurs inside the spaceship which takes a time of 80 seconds (say) as measured by a clock inside the spaceship thus moving with it.

Now consider a stationary observer outside the spaceship with a clock in hand measuring time. The time recorded by him for the same event that occurred inside the spaceship will 100 seconds as calculated from the special theory of relativity.

This means that 80 seconds for an astronaut inside a spaceship moving with a speed of 0.6 times the speed of light is equivalent to 100 seconds for us on Earth. Time has run slow for the astronaut as compared to time on Earth. That’s what we called dilation of time.

Note: Both the above phenomenon are true and practically observed

Twin Paradox

This is a scenario that evolves as a result of time dilation. Suppose we have an identical twin. Lets name them X and Y. We send X for a space travel for some years, say 50 years (time passed on Earth, i.e. time on Y’s clock who stayed on Earth) at speed of 0.8 times the speed of light.

Then from our calculations of special theory we see that for X the corresponding time spent in space will be just 35 years (time on X’s clock who went for the space travel). So when X returns to Earth after his space journey then X and Y are no longer twins. X is younger than Y by 15 years. 

35 years in space was equivalent to 50 years on Earth.

Now isn’t that difficult to digest!!! But it is true. Practically it has been verified for astronauts who go for space expeditions. On their return they look younger than expected. This is in fact regarded as time travel in future.

Now this difference in time elapsed on Earth and in space can be regulated. It can be increased by increasing the speed of the spaceship. 

An unbelievable scenario that defies human imagination

Suppose we consider a scenario when the spaceship carrying X is passing by a black hole or any gigantic body which has immense gravitational pull. It will be gain a speed almost equal to the speed of light.

In that case our calculations will give terrifying results. A few hours on the spaceship can amount to a few years on Earth. Difference between the ages of X and Y will increase more and more.

So it is quite possible that the timeline of human relations that we generally know can get defied. For example a son or daughter staying on Earth can become older than his or her father who has gone for a space travel and met that black hole. The father has actually performed a time travel in future and met his daughter who is quite old by that time. Now isn’t that mind blowing!!! That’s special theory of relativity for you.

"When you are courting a nice girl an hour seems like a second. When you sit on a red-hot cinder a second seems like an hour. That's relativity."

......Albert Einstein

Note:   We will discuss the General theory of Relativity in our next article.

By Prabir Rudra

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Prisoners of Space and Time

Prisoners of Space and Time:

Prisoner of time:

Right from the dawn of ages, human beings have always been a prisoner of time. Time has kept on flowing uni-directionally, unconditionally, and above all uninterestingly without giving us any break at all. Probably it presents us with the best natural example of continuity. 

Sand clock showing the passage of time

Enormity of Time

Great men like Albert Einstein have pondered over the nature of time and tried to understand its fabric. But it is unfortunate that the mystery of time remains unsolved till date. Man has almost reconciled to his fate of not being able to gain control over the flow of time and use it to his advantage.

Einstein and Time

                                    

                                                 

There is no going forward or backward in time for man. Once a moment passes it will be lost forever in the infiniteness of time. All of us long for our childhood days and hope against hope that it would be great to be able to relive those days once more in a lifetime. 

Likewise a point of time in future cannot be lived before it actually arrives by the natural flow of time. We are the captives of time in a helpless situation. The invisible prison holds us tight and we have no way out. This victory of time over man is so comprehensive that it has compelled him to live within the vicious cycle of life and death.

Prisoner of Time

                                               

The much awaited time machine is just an item of fiction for the time being and probably for many years to come. Our knowledge of time is so constrained that even the thought of a time machine seems to be an utter luxury for the time being. Our ignorance has pushed us to such a point that time itself seems to be an illusion to us!!! The illusion of time keeps wielding its magic over us.

The illusion of Time Travel

                                          

Prisoner of Space:

Most of us will think that we are free to move around in space with unlimited freedom. Indeed we can move freely forward and backward, up and down, left and right. That allows us three dimensional motion through space. In that sense we are really free to move spatially. Here we will consider a different point of view of motion through space.

We know that we can move through space. No doubt about that. Now we ask the question how far can we move or how far have we moved till now?

We know that we have travelled to Moon whose distance is 384400 kilometres from Earth. May be we will travel to Mars in near future which is at a distance of 54.6 million kilometres from us. Thats all!!

Our Moon

                                                   

The Mars

                                                    

                                                  Which is our nearest star? 

Most of us know that it is the Proxima Centauri situated in the Alpha Centauri system. It is situated at a distance of 4.2 light years away from us. Now 1 light year is the distance that light travels in a year at an enormous speed of 300000 kilometre/second.  Now if we calculate we see that,

                                   1 light year=  9461,000,000,000 Kilometres.

Proxima Centauri

                                                  

Our Latest Technology:

Nasa’s Juno probe is currently the fastest spacecraft built by man. It was slipped into an orbit around Jupiter in July, 2016. It briefly clocked around 2,66,000 kilometres/hour (1,65,000 miles/hour) making it the fastest till date. This was certainly assisted by sun’s own gravity.

Nasa’s Juno probe 

Helios I and II, which started their journey way back in 1970’s reached speeds of around 2,41,000 kilometres/hour (1,50,000 miles/hour).

Nasa’s Parker Solar probe is set to beat all these records. By December, 2024 it will be at its peak speeding at around 6,92,000 kilometers/hour (4,30,000 miles/hour). With that speed we can travel from Washington DC to Tokyo under a minute. Now thats very fast!!

Nasa's Parker Solar probe

                                           

Other latest technology spacecrafts that we have built are Deep Space, New horizon, Voyager, etc. These have a maximum speed of around 60,000 kilometres/hour.

Our biggest Nightmare:

Even if we consider the highest speed attained or to be attained by our latest technology spacecraft (Parker solar probe in 2024) using repeated gravity assists the time taken to reach our nearest star (Proxima Centauri) will be around 6555 years. With an average human life span of 80 years, it will amount to more than 100 human generations. That’s ridiculous!!!!!

This means that an astronaut who decides to travel to Proxima Centauri or its exoplanet Proxima B, will never reach it in his lifetime or in a few lifetimes. He or she is defeated by his or her biological setup. In other words, the human life span seems to be totally inconducive to interstellar travel. These numbers are so staggering that space travel seems to be beyond the realm of practicality. Although we are free to move around at will our movement in space seems to be highly constrained when large distance travel is considered. In a sense, we are the prisoners of space as well.

Prisoner of Space

                                                  

Very little time in hand:

With the expansion of the Universe, the stars, the planets, the moons, the galaxies are all moving away from us every second. With the passage of time it becomes more and more difficult for research and for any realistic chance for an interstellar travel. We have to act very fast otherwise it might be too late. Everything might go beyond our reach and we will be left contemplating in despair.

                        

                                What if we fail!!

The result of our incapability will be terrifying. It will have far reaching consequences than it seems. Probably our future generations are going to see a dark starless sky only to live and die believing that they are alone in this universe with nowhere to go. What a boring life that would be deprived from the beauties of heavens!! The stories of stars, planets, galaxies will only become fantasy tales for them which they will pass on from generation to generation as legends. Slowly and silently time is leading us towards such a terrible situation.

Space Travel: A choice or a compulsion for us?

With the advent of science and technology human civilization have reached new heights. But every success has its disadvantages as well. Pollution, deforestation, ozone layer deflation, use of nuclear weapons, etc. have led to global warming on large scale. This has eventually led to the melting of polar ice cap and rise in sea level all over the planet.

Effect of Global warming

Rise of Sea Levels is threatening life on Earth

The effect on life is already visible. Already a lot of species of animals have become extinct and the number is on the rise as the days go by.

Slowly but surely this will catch up with the humans in near future. The end of days is not very far away! Earth will not be a suitable place to sustain life for a long time unless we take serious steps to preserve it.

 The End of Days (The catastrophe leading to human extinction)

                   

In such a situation we have to think of an alternative home for us. We should attempt more and more space travel in the quest of some other planet that can sustain life and think of colonizing it. Some exoplanets have shown promising signs and are already on the list. So space travel will no longer be a choice but soon a compulsion for the human race in order to save it from extinction.

Our dream of Colonizing some other planet

We know that we have already thought of warp drives, worm holes, etc that can assist in our venture. But unfortunately, they are still mere theories and are considered as objects of science fiction pictured in Hollywood movies. We need to get practical results from our theories very soon.

Let us hope that we will soon understand the secrets of the fabrics of space and time and reveal the mysteries of nature. This along with our technological advances will help us realize our dream of interstellar travel and liberate us from the invisible prison of space.

By Prabir Rudra

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