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IN QUEST OF INFINITY - 04
By Prof G. Venkataraman


Previous Articles In The Same Series

THE BIRTH AND DEATH OF STARS CONTINUES....

Loving Sai Ram and greetings. I hope you are ready to resume our journey from where we left off last time. On that occasion, I told you about how [some] stars finally end their life as a White Dwarf, and how young Chandrasekhar made an astounding discovery about the White Dwarf. To recall briefly, Chandra not only confirmed that quantum mechanics creates an outward pressure [called degeneracy pressure of the electrons] that prevents the stellar corpse from being relentlessly crushed by gravity [as Fowler of Cambridge had already pointed out] but added a new twist. According to Chandra, when the mass of the dead star equals 1.44 times the mass of our Sun, then even the degeneracy pressure due to electrons fails to prevent gravity from asserting itself. Thus, in Chandra’s analysis, a stellar corpse of mass 1.44 times the solar mass would be crushed to a point. That of course is ruled out by physics and so young Chandra merely ended by wondering what new physics would intervene to take over and prevent this undesirable collapse. It is here that Chandra’s discovery was stunning. As passing years have revealed, there is in fact wonderful physics that became revealed over the decades, and it is that story we shall be concerned with presently.

A New Discovery: The Neutron

The first step in going beyond Chandra was taken by Lev Landau, a brilliant Russian physicist, who in 1932 argued that electron degeneracy pressure would not and cannot work beyond a point, and the reason for that was relativity. Remember I told you that where Chandra went beyond Cambridge Don Fowler was in adding relativity to quantum mechanics, and that was what changed the whole story. What Landau was now saying was,

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Russian Physicist Lev Landau
 
Sir James Chadwick

“Hey, hold on a minute. True, relativity is a must and sure it modifies the repulsive pressure the electrons generate, opposing gravitational collapse of the White Dwarf. But you know what? As the mass of the star increases, there are more and more electrons and in this situation of much higher electron density, you find that the electrons have to move really very fast, faster than light in fact. But Prof. Einstein would not allow that, which means that something else must happen, not discussed hitherto.”

Landau argued that maybe some other particle of Nature, not known till then, might step in. Boy, was that a great guess! Almost close on the heels of Landau, a man named Chadwick in Cambridge [a student of Rutherford, the Titan of nuclear physics in England ] discovered a new particle named the neutron. The neutron was more or less of the same mass as the proton [an important component of the atomic nucleus] but slightly heavier. What was more important was that the neutron was electrically neutral, quite unlike the electron which carried a negative charge and the proton which carried a positive charge.

Baade and Zwicky: From Supernovas to Neutron Stars

So how could the neutron make any difference? That was pointed out by Fritz Zwicky. Zwicky was born in Bulgaria in 1898 but went to live with his grandparents in Switzerland at the age of six. In 1916, he enrolled in the University and earned a degree in theoretical physics. During this period, Zwicky met Einstein, Pauli and interestingly enough also Lenin [the Father of the Russian Revolution of 1918]. After getting his Ph.D, Zwicky moved to America and ended up in California where he teamed up with Walter Baade who had migrated from Germany. Both were at the Mount Wilson Observatory, and after studying bright novae inside galaxies made a remarkable observation. They wrote:

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Dr. Fritz Zwicky
 
Physicist Walter Baade

We advance the view that a super-nova represents the transition of an ordinary star into a neutron star, consisting mainly of neutrons. Such a star may possess a very small radius and an extremely high density. As neutrons can be packed much more closely than ordinary nuclei and electrons, the ‘gravitational packing’ energy in a cold neutron star may become very large …. A neutron star would therefore represent the most stable configuration of matter as such.

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Mr. Robert Oppenheimer
 

What Baade and Zwicky were doing is start where Chandra left off, and pick up where Landau gave a new opening. And by doing this, they “invented” the neutron star! Of course, all this was done with words, meaning that it was more of an idea that a proper theory. The proper theory came a few years later in 1939, almost on the eve of the World War, when Robert Oppenheimer [later to head the atom bomb project] and George Volkoff, who worked out in detail the physics of stellar collapse and thus gave a formal theory for the formation of a neutron star.

Now you may say: “Wait a minute. Baade and Zwicky were studying novae or cosmic gas clouds and in that process came up with the idea of a neutron star. What precisely is the connection between the two that is, between a nova and a neutron star?” Good question and that is what we shall now consider. What I am going to describe is the picture that has emerged over decades, and an amazing picture it truly is! Let us consider a “dead” star, that is, a star that has ceased thermo-nuclear burn and is now collapsing due to the overwhelming force of gravity.

This “corpse’ has a mass say 1.44 times the mass of the Sun. Remember this is the Chandrasekhar Limit, when physics of those times threw in the towel. Here is a blow by blow account of what happens at that limit, in the light of present knowledge.

  • To start with, the stellar remains start collapsing, thanks to gravitational crush.
  • The inward crush is resisted by the electron degeneracy pressure, which acts towards the outside.
  • However, because the mass is 1.44 times the solar mass, electron degeneracy pressure is not able to stop the ruthless force of gravity. Why? Because to really stand up to gravity, the electrons have to move faster than light, which of course Prof Einstein will not permit. So gravity wins and electrons quit!
  • The gravitational squeeze now becomes maddeningly fast and believe it or not in about a second or so, the gas cloud shrinks from a size of, I don't know, several hundreds of thousands of km to just 10 km! Mind you, all this in the twinkling of an eye! This is what happens in the core.
  • As a result of this amazingly rapid squeeze, the shrunk core overshoots, going beyond what it shoots. It then sort of recoils outwards [this is like an overswing followed by a reverse rebound], and this recoil collides with the matter that is continuing to [slowly] fall from the outer layers earlier left behind in the fast crush.
  • That collision [between the rebounding matter from the highly compressed core and inward falling matter] then generates a shock wave, which swiftly travels outward, meeting the outer layers of the collapsing cloud. You have to remember that during the gravitational crunch, the speed with which different layers move inwards depends on the gravitational force that acts on the layer concerned. The force is more for inner layers, which is why they move much, much faster than the outer layers. It is the vast difference in the layer speeds, that creates the scenario described above.
  • Let us for a moment go back to the crushed “core” and examine its nature.
  • This core contains neutrons. Where did these neutrons come from? Recall we started with a gas cloud containing nuclei of all sorts including that of iron and of course lots of electrons. All these get crushed, and due to that crush, the nuclei get stripped into protons and neutrons [of which all nuclei are made]. Further, the electrons which cannot exist as electrons [because if they do they have to move faster than light, which of course is banned] combine with protons to become neutrons. Thus it is that the core is essentially made up of neutrons. We now return to the shock wave travelling outwards and away from the core.
  • On the periphery of the collapsing cloud, a different scenario is being enacted. The shock wave has arrived there and crushing the layers there.
  • The crush due to the shock generates heating. Remember these outer layers contain nuclei. Heat generated by the shock now triggers thermonuclear reactions in the nuclei [lighter than iron of course], and in the process, many neutrons are produced.
  • These neutrons get absorbed in the nuclei present in the outer layers. In a fraction of a second, these nuclei absorb many, many neutrons and transform to elements much heavier than iron, elements like mercury, silver, gold, uranium and so on. You know something? All the gold and uranium on our earth is the remnant of some ancient stellar explosion! So, our earth can, in a manner of speaking, trace its ancestry to a star that lived long ago!
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    Italian Physicist Enrico Fermi
    To complete the story, when the shock wave triggers thermo-nuclear reactions in the outer periphery, there is an explosion and a bright flash, which is what we normally call a super-nova explosion. This explosion is very bright, incredibly bright in fact, and soon I shall tell you how bright. In short, while a neutron core is being formed, the shock wave generated by it creates a super powerful thermo-nuclear bomb in the periphery! Who says natural phenomena are dull!?
  • One or two more facts to wrap it all up. Going back to the formation of a neutron core due to massive compression in an incredibly short time, you might ask: “But surely this would generate a lot of energy! How does that energy get released? Is it as heat or light?” And the answer is neither. The enormous energy gets released with the liberation of an incredible number of very tiny electrically neutral particles called neutrinos. By the way, the name neutrino was first used by the famous Italian Physicist Enrico Fermi; in Italian the suffix ‘no’ is often used to indicate something small, like bambino for a baby. Fermi was trying to convey that the neutrino was like the neutron but small.

To repeat all that in different words, in short this is what happens:

1. First there is a gravitational collapse, with all layers in the collapsing gas cloud moving inwards. The inner layers move fast while outer layers move slow.

2. The inner layers soon start moving with incredible speed, crushing the interior into a dense core, which is made up of neutrons.

3. The core is formed at such a terrific speed, its surface rebounds, meeting the matter from outer layers slowly falling inwards.

4. This generates a shock wave that travels fast outwards.

5. The outward travelling shock them meets the layers of nuclei in the outer regions and compresses that those layers.

6. This generates extreme heat, triggering thermo-nuclear reactions.

7. An explosion then results and a there is a bright flash, the supernova flash.

8. The two events, the formation of the neutron core and the simultaneous release of an intense neutrino burst, followed by the supernova explosion in the “outer” region are connected, being two aspects of one story; the formation of the neutron core is the ‘first’ chapter so to speak while the supernova explosion is the ‘second’ chapter. Very little time elapses between the two, though they are distinct aspects.

I am sure all this would make your head dizzy, and so to help you, we have series of sketches that illustrate the process described here in words. Please take a good look at the text and the accompanying sketches.

Hearing the Bell Toll for a Dead Star

You may now say: “Nice story, but how do we know it is all true?” Fair enough, and that is where human curiosity and ingenuity show up brilliantly. The “story” I have just told has been put together from various events that happened in history, and maybe I should start in 1967 with a young lady named Jocelyn Bell, a student of astronomer Anthony Hewish of Cambridge, who was scanning the sky with a radio telescope looking for turbulence in stellar plasmas far, far away. On November 28, Bell recorded a strange radio signal; it was amazingly periodic, with a period of about 1.3 seconds.

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Ms. Jocelyn Bell
 
Astronomer Anthony Hewish

She just could not make heads or tails of this incredible signal, because till then, there was no reason to expect a radio signal from outer space with such extra-ordinary regularity. Could it be that these were signals from some intelligent beings out there? No one knew, and these signals were simply dubbed LGM standing for “little green men”! Bell and her supervisor were not serious that these signals actually came from little green men, but a name had to be given, and this seemed a nice and intriguing one to give!

This is what Jocelyn Bell said later:

As the chart flowed under the pen [Hewish and Bell used a pen recorder like they use in ECG machines] I could see that the signal was a series of pulses, and my suspicion that they were equally spaced was confirmed as soon as I got the chart off the recorder. They were 1.33 seconds apart. I contacted Tony Hewish who was teaching an undergraduate lab in Cambridge and his first reaction was that they must be man-made. This was very sensible response to the circumstances, but due to a remarkable depth of ignorance. I did not see why they could not be from a star.

And indeed, from a [dead] star they were! Later, Hewish shared the Nobel Prize for his discovery!!

Intensive investigations followed and soon it was discovered that these signals actually came not from intelligent beings but from an astral object the like of which had never been detected before. This pulsating radio source of natural origin was named a pulsar. Since then, hundreds of pulsars have been detected in all parts of the sky.

The question now became: “What are these pulsars?” From the short pulse duration and the rapid rate, it became evident that pulsars must be exceedingly small objects. The fact that pulsars were radiating radio signals meant that there must be moving charges in them. [According to the laws of physics, if there is electromagnetic radiation, then that means there must be moving charges.] And the fact the radio signals were coming in the form of short pulses meant that pulsars must be rotating fast, acting like lighthouses and emitting radio waves instead of light.

The Pulsar - A Signal of Nebulous Origins

All this is fine but why pulsars and how did they form? The clue to that came when a pulsar was discovered right in the middle of the famous Crab Nebula. This pulsar was pulsating at 30 times a second. I must here digress and narrate briefly the history of the Crab Nebula. This was discovered in 1731 by the British astronomer John Bevis. Charles Messier independently found it in 1758 when he was looking for the famous Halley’s comet; in fact, Messier first mistook this nebula to be a comet but later corrected himself. This gaseous object or nebula was christened the “Crab Nebula” on the basis of a drawing made by Lord Rosse around 1844, and since then the name has stayed. In 1921, J.C. Duncan of Mt. Wilson Observatory in California discovered by comparing two pictures of the Crab Nebula taken about 11.5 years apart that the nebula was in fact expanding.

From the expansion rate, Duncan deduces that the nebula was probably born about 900 years earlier in some cosmic event. This backtracking 900 years is significant because it took one to around the year 1054 A.D. That story soon but first I must tell you that Knut Lundmark of Sweden also noted in 1921 that the Crab went back about 900 years and in fact its location was very close to where a spectacular astronomical event had been seen in 1054. This brings us to the story of 1054, which is remarkable tale in itself.

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The Crab Nebula hides and secret...
 
A Neutron Star! (seen here under X-Ray telescope)

On 4 th July that year [4th of July by the way, happens to be America ’s Independence day! Was this God’s gift to America several hundred years before it was born?!] Chinese astronomers noted a “guest star” in constellation Taurus. At least four Chinese astronomers left records and one Japanese observer too has noted this sudden appearance of a “star” on that day in the sky. One astronomer, Yang Wei-te presented this report to the Emperor of China on August 27th:

Prostrating before Your Majesty, I hereby report that a guest star has appeared; above the star in question there is a faint glow, yellow in colour. If one carefully examines the prognostications concerning the Emperor, the interpretations is as follows: The fact that the guest star does not trespass against Pi the Lunar mansion in the Taurus and its brightness is full means that there is a person of great wisdom and virtue in the country. I beg this to be handed over to the Bureau of Historiography.

According to the Chinese records, when it first appeared, the “guest star” was so bright it could be seen during daytime. When it was one week old, the remnant cloud was as big as the solar system and as bright as the Sun! For twenty three days, the luminous cloud could be seen during day time. After four weeks, the cloud was visible only during night. It kept getting fainter and fainter, and after 653 days, was no longer visible to the naked eye. It was that very same cloud that was later picked up by European astronomers viewing through the telescope, and subsequently named the Crab Nebula.

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A Native American carving depicting a supernova

By the way, intensely bright though it was, the supernova explosion of 1054 A.D was not seen by Indian astronomers but then that is understandable because July is the peak of the South West Monsoon in India, when the sky is covered with clouds practically all the time. Interestingly, Arabian astronomers and observers in Europe also missed but not so the Indian tribes in Arizona. Carvings in caves discovered in the mid-fifties suggest that they too saw the event. This is based on the fact that in the carving, the crescent moon is very close to the star, which was the case for observers viewing from North America. Putting all this together, Baade and Zwicky in fact argued that there must be a neutron star in the Crab Nebula. But at that time, no one knew and no one could assert either.

The discovery of the pulsar changed all that. People said, “Let us say that the Crab is a supernova remnant and that the bang occurred in 1054. If so, a neutron star must have been born then. Maybe the neutron star also acted like a pulsar. Let us look at the centre of the Crab to see if there is a pulsar there.” Many astronomers did, and lo and behold, there was a pulsar there!

The Aurora Borealis of the Universe

You might still shake your head say, “Wait a minute. I agree that the birth of a neutron star is signalled by a huge SN explosion that might sometimes even be seen by the naked eye [by the way, after 1054, there have been other sightings but more about that a bit later]. But how come the neutron star behaves like a pulsar?” Valid question and there have been detailed theoretical studies on that. There are the following considerations that form a part of the argument.

  • To start with, though electrically neutral, each neutron acts like a tiny magnet. Since there are trillions and trillions of neutrons in a neutron star [its density is amazingly high], the neutron star as a whole behaves like an extremely powerful magnet. Thus, the neutron star would have a magnetic north pole and a magnetic south pole, even as our Earth does. But unlike the Earth, the magnet that the neutron star represents would be unimaginably powerful.
  • Next, when free, a neutron can disintegrate due to radioactive forces into a proton and electron, both of which, please note, carry electrical charge.
  • This disintegration cannot happen in the interior of the neutron star where the density is too high, but in the outermost region, this is certainly possible.
  • Thus, like an onionskin, the neutron star could have charged particles in its outer layer.
  • Some of these particles could escape from the surface but they cannot quite get away. Dragged by the magnetic field, they would spiral into the polar regions.
  • Am I making all this up? By no means. All this is not only mandated by the laws of physics but in fact, even on earth, charged particles in the upper atmosphere do spiral into the geomagnetic north and south poles. And when they do, they give rise to the phenomenon of Aurora Borealis and Aurora Australis.

OK, like on earth, when charged particles on the surface of the neutron star fall into the magnetic poles of the neutron star, they emit electromagnetic radiation. This radiation could be in the form of radio signals, of light, and even x-rays.

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The Northern Lights: The Aurora Borealis
 
The Aurora Australis seen from the space shuttle

All this is fine. How come the signals are emitted as pulses? Does that mean that particles fall into the poles, take rest, resume their falling and so on? Not at all! You see, due to angular momentum effects, the neutron star is spinning all the time like our Earth does, and our Sun does too. If you take that into account, you end up with a celestial lighthouse! Ever seen a lighthouse? It is always emitting light but since it is rotating, the light is always directed in one direction [two if you want to be technically fussy!]. Thus, an observer on earth would receive electromagnetic signals from a neutron star/pulsar only when the radiation beam sweeps the antenna; very similar to a sailor seeing the lighthouse only when the light beam sweeps across him.

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I think we should pause and let all this sink slowly!

  • We started with a stellar corpse with a mass say more than 1.44 solar mass.
  • We then said that such a mass cannot become a White Dwarf; Chandra would not allow that.
  • But Baade and Zwicky, backed by Oppenheimer and Volkoff, say no problem. This object would become a neutron star.
  • However, the transformation of the gaseous remnant into a neutron star would do two things. First, it would release an INCREDIBLE amount of energy, about which I have not said anything so far but would shortly.
  • The formation of the neutron star is accompanied by the generation of a powerful shock wave that, travelling outwards, compresses and heats those outer layers.
  • The atomic nuclei in those layers then undergo thermo-nuclear reactions, during which process there is copious neutron production.
  • Most of these neutrons get capture in those layers, generating new elements far heavier than iron.
  • At this stage, there are two entities, a neutron core that is very small and dense and a gaseous outer layer, the remnant of shock heating, thermo-nuclear transformation and all that. That layer is gaseous in nature and contains heavy elements, not a part of the original stellar corpse that had only elements up to iron.
  • The neutron star [it is not really a star in the usual sense we use the word!] now spins and continues its existence while the outer gas cloud slowly expands [this is what is happening in the Crab, for example].
  • And thanks to the electrons and protons in the outer layer of the neutron star, the neutron star tells everyone about its presence by acting as a celestial lighthouse!

Wow, what a story! At this point, I must add some important additional facts.

Super Facts about Supernovas

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Artist's rendition of a supernova explosion

First about supernova sightings. I told you that the Chinese observed a great event in 1054 A.D. Any other such sightings? Yes, there have been many, and two significant and reliable ones are 1) by Tycho Brahe in 1572, and 2) Kepler in 1604. Both these are universally accepted. A third important one is that which occurred in 1987, concerning which I give some interesting facts separately.

These days, astronomers regularly track and study SN explosions and using fancy telescope a large number have been detected. In fact, the study of SN is an active subject in itself that has led to many wonderful insights into the nature of our amazing Universe.

Next, the amount of energy released in the SN explosion. Careful studies made on the recent SN 1987 A event give a good idea. In this, the sudden formation of the neutron core released an energy equivalent to that which would be generated if 1/10 th of the mass of our Sun were to be converted all into energy, and this happened almost instantly. For your reference, the mass of our Sun is about 2 x 10 30 kg; one tenth of that would mean 2 x 10 29 kg or 2 x 10 32 grams. Imagine that! Hiroshima was devastated when a mere 5 grams of matter was converted into energy. And now, we are talking of one tenth the mass of the Sun all being converted into energy in a fraction of a second! Mind boggling, is it not?!

Now how is this energy released? Whereas our Sun releases energy in the form of electromagnetic radiation mainly, when a neutron star is formed, energy is released in the form of neutrinos. These neutrinos, as I told you earlier, are extremely tiny. They are as tiny as the electron but with much less mass; they therefore travel almost at the speed of light. You know how many neutrinos were released in the SN 1987 A formation/explosion? A cool 10 58 neutrinos! That number, by the way, means 1 followed by 58 zeros! We can’t even imagine such a number, can we?! That is Nature, all sorts of amazing things happen there.

Detecting Neutrinos is no Small Matter

You may ask, “How do we know that neutrinos are actually emitted?” We know because scientists have actually detected the neutrinos emitted by SN 1987 A! That is a fabulous story and I must give you the highlights of that. It all starts with a group of Japanese scientists who in collaboration with some scientists from America were involved in a difficult experiment to check if the proton would ever decay by itself due to radioactivity. From the point of basic Physics, this was a crucial experiment and many years and many millions of dollars were spent in setting this experiment underground in a place in Japan.

The scientists waited and waited – the proton decay experiment is a very difficult one but the result was expected of vital importance to Physics, which is why so much effort went into designing that experiment. Of course, data collection was all automatic, done with computers, 24/7.

One day during this long, long wait, the scientists heard that astronomers had detected a SN explosion on 23rd February. These scientists then said, “Hey, our detector can detect neutrinos. If neutrinos had been emitted, then some of them would reach the earth. Of those reaching the earth, some would hit our detector. And since our detector can detect neutrinos, some of those hitting our detector would actually have left their signatures behind. So why not we look for those tell-tale signatures?” That precisely is what they did. It was truly a needle-in-a-haystack kind of detection, but the effort seemed worth it.

The detector In Japan that caught Neutrinos from the 1987 supernova explosion

I said earlier that about 10 58 neutrinos were emitted in the SN event. Of these only about 10 16 or ten-thousand trillion neutrinos hit the detector in Japan . And do you know how many of these 10 16 were actually detected? Just twelve, yes only 12, but the scientists were damn sure of every neutrino they had caught. Believe me, it is not easy to get the world to accept this kind of data, but the entire scientific world not only accepted all this but also applauded, including by awarding Masatoshi Koshiba the leader of the Japanese team with the Nobel Prize.

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The Scintillator Neutrino Detector, Japan
 
Scientist Masatoshi Koshiba

Incidentally, I urge you to take a look at Boxes 1 and 2, where some info about neutron stars etc. is assembled.

God Allows Us to See His Cosmic Form

You know, when I think about it all, I am simply wonder struck. On one side of it is God who has created the Universe in which all these wonderful things happen. On the other side, there He is in human form in Parthi, going about as if He is not aware of any of the mysteries in the Universe He has created. But do not be fooled by that great put on. Five thousand years ago, Arjuna was fooled in precisely this manner, with the Lord taking Arjuna for a ride for about seventy and odd years. But then, on the battlefield in Kurukshetra, Krishna said, “Arjuna, do not be fooled, and take a look at My Cosmic Form!” Swami blessed Arjuna and gave him special powers to behold the Cosmic Form – the famous Viswaroopa!

Many a time, I have seen boys in the old days praying to Swami, “Swami, please show us the Cosmic Form!” And the Lord would smile and reply, “What is there for Me to show specially? It is there all round you. See it and feel amazed; Everything you see around you is an aspect of My Cosmic Form. Understand that!”

What I am trying to say is that when we see Swami during Darshan, we must not only rejoice in that beautiful form of matchless beauty, but also take a minute off to appreciate that hidden in this form is the enormous Cosmic Power that animates the Universe.

Let us also take a minute off to realise how much man has unravelled of the mysteries of God’s Creation. All that I told you about the White Dwarf, neutron stars, pulsars, SN explosions etc., have been discovered by man simply by sheer brain power combined with ingenious experiments and amazing instruments, including those sent into space. Newton once said that the thumb alone is enough to prove that God exists. I would say that man’s achievements alone are enough to prove that God exists. It is the power of God packed into the human frame that enables man to do the many things he is so very proud of. Man is constantly proud of his achievements but as Swami told Arjuna, man is able to do all this [and much more] because God has blessed him with all that incredible capacity and capability. Alas, man does not remember that! That is man’s great foolishness and tragedy.

 
sai-mudra

Yes dear reader, the road to Infinity that we are trekking along is filled with amazing scenes; but do not be surprised if the road eventually ends within us! But that comes later!! Meanwhile, thanks for your company and all the best till we meet again.

Jai Sai Ram.

BOX 1

Turning next to the progenitor, the figure below gives a rough schematic of a star of about 20 times the solar mass, before it is ready to settle down into a final state.

Turning now to some interesting numbers about neutron stars, don’t imagine that just because the neutron stars are small, they are insignificant! Their enormous density gives them enormous power! Know about escape velocity, the velocity with which an object must move to escape the gravity of the celestial object on which it is located? I am sure you are aware that the escape velocity on earth is about 11.2 km/sec that is to say, if we want to launch an object into space from the surface of the earth, we must make it move upwards with this velocity. This is a big number and it is for generating this velocity that the space people employ huge rockets. Turning to the neutron star, do you know what the escape velocity there is? Any idea? It is a whopping 0.5 c or about half the speed of light! That is to say, it is around 150,000 km/sec! Small the neutron star may be, but what a mighty punch it carries!

Another impressive number. Suppose you drop a 1 kg object from a height of 1 metre. It would of course fall towards the earth and hit it with a thud; we all know that. If you did that on a neutron star, do you know how powerful that thud would be? It would have the energy of two thousand hydrogen bombs!

I am mentioning all these numbers for several reasons.

  • Firstly, we must realise there are amazing forces at work out there in space.
  • Secondly, when we see Swami or think of Him, let us also remember that it is He who is orchestrating all these incredible forces.
  • Thirdly, the neutron star is too tiny to be seen with any telescope that man can ever build. Yet, he has devised clever methods and reasoning to infer their presence, and also designed remarkable instruments to detect them through the radiations they emit as pulsars etc.

God is infinitely powerful but God has also packed samples of that infinite power into man. That is why the Upanishads declare, “Poornam adam, Poornam idam, …” etc., meaning roughly: “This and that are the same; one is the Macrocosm while the other is the microcosm."

Spend a minute to appreciate how much man has learnt about the physical aspect of the Cosmos just by gazing at the sky, wondering what’s up there, and devising clever and ingenious means of finding out what’s going on out there! You will then appreciate how much power God has given man to satisfy his curiosity.

Yes, stunning aspects of Infinity are already manifest in the Physical Universe but then that ought not to be surprising because, as Krishna explains, the Universe is the manifest aspect of His Divinity. God has given man the capacity to cognise also the Un-manifest Divinity, but alas, that is what man consistently misses, not because God has not equipped to cognise this Universally-present subtle aspect of Divinity but because he is too drunk with his “achievements”. That is a different story, that we shall discuss later in our quest.

BOX 2

CONCERNING THE SUPERNOVA 1987A

We reproduce below extracts from an article on SN 1987A by Richard McCray. This would offer some further insight into the SN phenomenon.

On the evening of February 23, 1987, a young Canadian astronomer named Ian Shelton took a photo of a nearby galaxy, the Large Magellanic Cloud (LMC) with his Nikon Camera. Shelton developed the photo and immediately noticed a bright star where none had been seen before. He told his colleagues, and within hours the word had sped around the world, by phone, e-mail and fax. This was a nearby supernova -- the brightest one to be seen since 1604 AD, when Johannes Kepler observed a supernova in our own galaxy.

supernova

Supernova 1987A before and after the explosion. The arrow in the panel on the right points at the blue giant parent of the supernova before it blew up. The panel on the left shows the supernova about 2 months after the explosion. Copyright by Anglo-Australian Observatory.

Before it blew up, it was already a fairly luminous (about 10 5 times the Sun) blue star; but after the explosion it suddenly became 1000 times brighter (about 10 8 times the Sun), as seen on the left panel.

From its location in the LMC, the light from SN1987A must travel for about 160,000 years before it reaches the Earth. So, when Ian Shelton first saw the supernova explode in 1987, he saw an event that had actually occurred in about 158,013 BC (1987 - 160,000 years). Today, when we look at the event with a telescope, we are seeing a delayed-action re-run of the actual event. [The temperature associated with the neutron core formation is about 40 billion degrees, and the event happens in about 10 seconds!]

The light from SN1987A faded at almost exactly the same rate observed in laboratories for the decay of the radioactive nucleus Cobalt-56 into the stable nucleus Iron-56 (the half-life of Cobalt-56 is 77 days). This was not a great surprise, because astronomers had long suspected that supernova explosions were responsible for the formation of the heavy elements in the universe. Theoretical calculations of the formation of heavy nuclei at billions of degrees (the temperature expected during the explosion) indicated that about this much Cobalt-56 would be formed. But the fact that the supernova light decayed just as expected was the strongest confirmation to date of the idea that supernova explosions really did make the heavy elements -- and, for the first time, we could measure exactly how much Cobalt-56 was made (0.07 Solar masses).

After 500 days the visible light faded even faster than the Cobalt-56 decay rate. That happened because after that time dust particles began to form in the supernova debris. The grains absorbed part of the optical radiation and converted it into infrared radiation. Moreover, the supernova debris had thinned out enough so that the gamma rays could escape directly without first becoming converted to optical light. In fact, gamma ray telescopes in space could observe these gamma ray photons, and they saw that the gamma ray photons had exactly the same energy as those produced by Cobalt-56 in laboratories on Earth. That clinched the idea that the supernova explosion made Cobalt-56. Think about it: the iron that makes your blood red was once radioactive Cobalt-56. It was produced in a supernova explosion several billions of years ago. The observations of gamma rays from SN1987A leave little doubt about that. The same with the oxygen you breathe, the calcium in your bones, and the earth you stand on. We are, literally, stardust. In fact, we might consider ourselves the consciences of supernovae: the creatures supernovae have created to worry about the consequences of their unruly outbursts.

Even though the supernova became as luminous as a billion Suns, the total energy of the light that it produced was a tiny fraction -- only 10 -4 -- of the energy released as neutrinos during the first few seconds after the collapse.

In 15 years, we have seen the debris of SN1987A cool from one of the hottest places in the universe (T > 10 10 K) to one of the cooler places (T < 100 K).


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Vol 5 Issue 04 - APRIL 2007
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