Colossal Himalayan Slides, Massive Pilgrims’ Stress and lessons from History: Gaia as Ardhanareshwar.

Gaia, the goddess who brought order out of chaos, was the appropriate title for a hypothesis about an Earth system that regulate its climate and chemistry so as to sustain habitability  --- James Lovelock (author of Gaia, a new look at life on earth, Revenge of Gaia).

What Lovelock wanted to say, has probably been earlier (much earlier) incorporated in our life-philosophies by the duo of Shiva and Shakti. This philosophy is perhaps best incorporated in Himalayan Hindu (Indian) philosophies by the concept of Ardhanareshwar --- half Shiva and half Parvathi, a manifestation of Shakti. I will briefly describe below an interpretation (my?) for those unfamiliar. For a visual image of Ardhanareshwar I choose Amita Pandey’s interpretation (Fig below) of Ardhanareshwar (http://fineartamerica.com/products/ardhnarishwar-shiv-amita-pandey-poster.html) which has Shiva in a tandaav dance and Parvati (or Shakti) with fire (energy) in her hand. I will, for convenience, also use the term Gaia philosophy (or just Gaia) which means the sustaining of the earth ecosystem by regulation and redress of trespasses from excesses.

The Colossal Himalayan devastations of 2013 involve not only landslides of hill slopes into the rivers below but also involve the thrusting up of ill-prepared, soft, people from the plains to unfamiliar hilly terrains. It is the catering to the unpreparedness of the latter that could have precipitated the former. These devastations being over for the moment, this blog would speculate on what has to be kept in mind before one attempt a recovery.

I have been reading newspapers and watching television for the last week or so, to understand objectively what reasons could have been behind the recent Himalayan devastations of 2013 must have tremendously increased television channel TRP ratings/profits. I did not get informed any better nor did I really expect to.

One would have expected these channels to have studied the problem a little more in detail and highlight what could have happened from a studied historical/technological viewpoint. In this way they could have perhaps succeeded in injecting a sense of responsibility into their usual irresponsible, ill-researched, and unnecessarily dramatized shrieks and screeches for TV audiences that like saas-bahu serials.

So I read up further on things that could be important to see whether I could have reinforced my earlier impressions that were formed during my early (pre-1980) contacts with tree-hugging (chipko) environmental activists. At that time Sunderlal Bahagunaji was echoing earlier concerns that deforestation and road-building was causing havoc on the hill-slopes because pf landslides of proportions not seen earlier at that time.

Even earlier to that time of my first Himalayan walk, I had read about the Gaia theory, and it had been reinforced by those early landslides and during conversations with the original mountain people, many of whom were of Tibetan-Nepali ethnicity, They shared the same belief even if they would not have heard of Lovelock nor Gaia. These hill people, however, would have lived the philosophy and thereby created and contributed to the worship of Ardhanareshwar even if they may have known it.

The Gaia hypothesis could also extend to the dangers of peopling the mountains by plainsmen. The hill-people carry the load of visiting un-acclimatized pilgrim plainsmen who can hardly stand straight on these steep slopes when they first land there. In these early days the outsiders from the plains with different ethnicity kept calling the hill-people bahadur much to their resentment. Gaia, must be having her method to keep these unfit people away from places where only the ethnic or fit (and gods) walk.

Post the tragedy, there has been statements that there will be reconstruction on a more massive scale. The Gaia hypothesis would say that Gaia’s revenge would be proportionately damaging. It is time we stepped back and let nature rebuild the safest way that only she knows and she can.

This blog will essentially agree with the refreshing view of Tom Alter on NDTV (27-06-2013) who spoke so eloquently on how one should pause, look back, go back to the old ways and let the wounds on the Himalayas recover. The blog was written before the interview. It will outline the reasons why we should do so.

Gaia as Ardhanareshwar

I started this blog keeping in mind James Lovelock’s Gaia hypothesis. I will save the details of this hypothesis for another blog. Most of the attention on Lovelock’s work concerns global warming. As some skeptic (Alain Bates) put it, some evidence for this hypothesis may lie in the changes in the size of swim-wears with increasing time of global heating as in the cartoon below.

I am not a skeptic, however. I like the concept of Gaia. The absence of global warming at rate predicted by Lovelock could only mean that Gaia is cooling down the earth by other mechanisms such as heavy rainfall, tornadoes, storms, landslides. The Gaia philosophy is, moreover, rooted in our blood, especially if we are not of the very clichéd and very real petit-bourgeois kind.

Just as a reminder or a paraphrase, this Gaia hypothesis is more familiar as a Mother Earth image that we (hindus and other pagans) instinctively have. It moulds (at least it used to) our mind to thinking that mother Earth looks after all her children equally. The essence of this philosophy is that in order to save the tiger one needs also to save the toads and the bugs and the weeds. This philosophy, I guess, should also include the notion that the very notion of looking after each other is more than just food for thought; it is food (or action) as well should we be hungry.

The Gaia hypothesis basically states that every harm that is seen by Mother Earth is redressed so as to restore the desired balance as perceived by her infinite wisdom and within her time-scale. The goddess Durga or Shakti  (right of figure 1 below) are figures of worship of those who already the mindset of Gaia.

It is the goddess Shakti who, I think, has the energy to restore balance. For this, Shakti or mother Earth has Shiva doing his dance of creation and destruction. Amita-Pandey’s image of Ardhanareshwar is therefore appropriate for this blog.

Shiva would be very unforgiving at times if Shakti urges him to be so. We therefore pray more to Shiva for forgiveness during his redress of trespasses. 

It is not as if the benevolent all-knowing mother Earth concept is not known to the ordinary Westerners. They may require giving it more tangible form especially once their religions bcame mono-theistic and institutionalized. One of these forms could be the goddess Venus (the yielding, watery female principle, essential to the generation and balance of life, --- Wikipedia). The birth of Venus is depicted in Fig 1, left (read legend, click to expand) as painted by Botticelli (1443-1510). As an aside, we should note that the main figure, Venus, in Botticelli’s very famous painting, Primavera (1482) has a very striking resemblance to the very young Simonetta Vespucci (1453-1476; Botticelli, I have read, was buried at the foot of her tomb 35 years after her death) who looks like Venus in The Birth of Venus. It is because of Simonetta that all of us ---certainly I --- like Primavera so much!  It requires a lot of love for Botticelli to choose her as Venus the mother goddess. Boticelli’s image of Venus is probably the basis for the image of Gaia in the modern (1990s) Elsie Russell’s altar painting (middle of picture above) even if Russell’s interpretation of the painting has a mix of everything including Pan, Jimi Hendrix with guitar, the Green Man (European deity of virgin forest), a snake goddess, as well as Dionysus (god of chaos, spontaneity, freedom, fertility).

Landslides and McAdam’s peril.

The question here is whether the landslides and devastation in the Uttarakhand area is Gaia’s redress of one of its inhabitant’s excess. If one jumps to conclusions,  as one must to begin with, it would seem (Fig 2) that the landslides are associated with man’s road building. In the image of landslides below (taken from a Landslide Blog of Durham University) it is clearly seen that the fan-shaped landslide begins from a point on a road. The devastation becomes bigger as the road become bigger and firmer with macadamized roads!

John Loudon McAdam, a Scot, laid his first roads in Bristol, Scotland.  Wikipedia informs us “McAdam's method was simpler, yet more effective at protecting roadways: he discovered that massive foundations of rock upon rock were unneces sary, and asserted that native soil alone would support the road and traffic upon it, as long as it was covered by a road crust that would protect the soil underneath from water and wear”.

 

We forget that the soil on the Himalayan terrain is not protected from water and from wear. How come this is not schoolboy knowledge as yet?

It would seem that, at least, for some parts of the Himalayan topography there is a limit to the size of the roads that can afford such a Macadam protection. In such cases Gaia takes her revenge through landslides. Torrents of water cut fast and deep through loose soil to form deep gorges. Mountain roads in the Garhwal hills should then avoid such gorges. A Gaia-safe road path (say, in the future) in the Himalayas must traverse through firm rocky terrain! Geologists need to find such terrain for roads that Gaia could approve. The small, older paths which skirt river sides should be left to the local people and foot-pilgrims.

When the reconstruction happens, as there is every greedy commercial reason for it to happen, one would be making broader roads. Maybe there will find more profit if there were concretized roads. It will not stop the landslides, however; they will only become larger and more devastating.

This reminds me of the effort of a very ‘religious’ professor of the college where I did my Ph. D. in chemistry. This professor was researching for his Ph. D. on, what he said, was the milk of the “Ongole bull”. He must have meant cow but could have preferred the term “ongole bull” which was making news at that time (late 1960s). He had to digest the milk with acid or something in a sealed tube that was heated in a oil bath. He did it very rarely, probably waiting for an auspicious time. After some time the tube would explode. He would come back on another auspicious day. He would use stronger tubes. The explosion would be delayed but would be stronger when it came. This went for some time. It finally stopped when the explosion carried the oil bath along with it. That stopped his experiments. He continued with his thesis and wrote a virtual one using the results and language of another thesis submitted to the university and only changing the caption from cow to the specimen of the ‘Ongole bull’. He got his Ph.D.! Gaia let’s you get away with it in the small mind-scales.

The moral of this story is that if one thinks one has to go to the Uttarakhand for religious salvation, one may as well do it with a virtual trip from home. Mother Earth would be extremely happy.

We learn a bit further from the history of early landslides on Himalayan slopes.

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Early Himalayan landslides.

One of my more favorite descriptions of landslides from my school days is that by Rudyard Kipling, Second Jungle book, Miracle of Purun Bhagat:

“There was a sigh in the air that grew to a mutter, and a mutter that grew into a roar, and a roar that passed all sense of hearing, and the hill-side on which the villagers stood was hit in the darkness and rocked to the elbow. Then a note as steady, deep, and true as the deep C of the organ drowned everything for perhaps five minutes, while the very roots of the pines quivered to it. It died away, and the sound of the rain falling on miles of hard ground and grass changed to the muffled drum of water on soft earth. That told its own tale.

“When (the day) came they looked across the valley and saw that what had been forest, and terraced field, and track-threaded grazing ground was one raw, red, fan-shaped smear, with a few trees flung head-down on the scarp. That red ran up the hill of their refuge, damming back the little river, which had begun to spread into a brick-colored lake. Of the village, of the road to the shrine, or the shrine itself, and the forest behind, there was no trace. For one mile in width and two thousand feet in sheer depth the mountain-side had gone away bodily, planed clean from head to heel.”

It is not clear if this landslide was Gaia’s revenge for some immediate man-made cause.

Kipling’s story was probably based on the great landslide of 1880 at Nainital. This landslide could easily have been due to the wrath of Gaia.

The Great Landslide of 1880 at Nainital. There used to be a wonderful, serene lake at Naini Tal, which was kept secret as a secluded piece of land not meant for ordinary mortals. The lake itself is thought to have been named after the eyes, Naina, of goddess  Sati (Parvathi), consort of Shiva (see Wikipedia). Sati was burnt in the holy fire of an yagna (holy offering). Shiva danced his tandaav dance with the burnt body of Sati on his shoulder. During this dance parts from Sati’s body fell. A Naina Devi temple was built at the spot where the eyes fell. There are many Naina Devi temples in India (the current more famous one is at Bilaspur) indicating, logically, that the event occurred several times in the universal cycle of creation and destruction? One of these spots is at Nainital which is marked as a Shakti peet, a place of worship for followers of Shakti. Landslides at Nainital¸ especially those around the Naina Devi temple would therefore be appropriate to the theme of this blog.

A great landslide occurred in 1880 when the Naina Devi temple was washed away,  along with a lot of the Nainital. Goddess Shakti, or mother Earth, did not require to be confined in a temple, after all.

The serenity of the Nainital lake could not be kept for long when people with different (say, monotheistic) attitudes became aware of it. The first westerners to visit Nainital were two Irish men of different attitudes. The contrast in their attitudes illustrates some of the main points in this blog.

One of the Irish was named Trail, a bureaucrat and Commissioner of Kumaon and Garhwal, who thought, like any other pre-existing environmentalist, that “crowds would violate the sanctity of the place” as he first saw it in 1823. Trail’s “power in Kumaon was practically unfettered and he exercised it jealously and disliked the possibility of any influx of European intruders in his domain” (based on J. M. Clay’s 1926 book on Nainital).

The more commercially appreciated person was the other Irish, Barron, a sugarcane merchant from Shajahanpur and hunter. He first saw the lake in 1839 and realized its potential as a hill resort. Barron carried with him a light 20-foot boat to the lake in 1940 and thereby became the first to boat in the lake to the delight of the local people who hailed him as Vishnu coming out of the lake. With the cunning that a modern CEO of a multinational developing, say, a Lavasa hill station would be proud of, Barron coerced the local thekedar, who claimed the lake and surroundings as his ancestral property, to take a ride to the middle of the lake in his private boat. He then threatened the thekedar, who did not know swimming, to throw him overboard if he did not sign the paper relinquishing his rights. Barron, who for some reason called himself a pilgrim when he wrote articles advocating Nainital as a resort, built a lodge for himself, Pilgrim’s Lodge, on a piece of land that was leased out to him for one-eighth of a rupee per year.

The rapid development of Nainital by the British is said to have started after the mutiny of 1857 as a refugee for civilians after its ‘horrors”.

The early serenity of the Nainital lake is perhaps captured in the 1867 figure on the top left of Fig 3. The question mark indicates asks whether the lodge on the hill could have been Barron’s Pilgrim’s lodge. The satellite image of Nainital as it stands now is shown on the top right of Fig 3. The Pilgrim’s Lodge compound (see circle in red in the figure below) still stands on the top of the Nainital club.  

In 1880 there was the great Landslide in Nainital. This landslide occurred before Kipling wrote Kim. A very often quoted description of this landslide in (http://www.oldindianphotos.in/2011/02/landslide-in-nainital-september-1880.html) Is as follows:-

In September 1880 a landslide (the Landslip of 1880) occurred at the north end of the town, burying 151 people. The first known landslide had occurred in 1866, and in 1879 there was a larger one at the same spot, Alma Hill, but "the great slip occurred in the following year, on Saturday 18 September 1880." "Two days preceding the slip there was heavy rain, ... 20 inches (508 millimetres) to 35 in (889 mm) fell during the 40 hours ending on Saturday morning, and the downpour still lasted and continued for hours after the slip. This heavy fall naturally brought down streams of water from the hill side, … At a quarter to two the landslip occurred ,,, The total number of dead and missing were 108 Indian and 43 British nationals.

In this landslide the old Naina Devi temple was washed away.

The photos before and after the landslide of 1880 is shown in the bottom of Fig 3. The landslide washed away a path carved out of the hills. It is not clear whether Barron’s Pilgrim lodge is the structure located on the top of the landslide or whether the road that was washed away led to his house. There is little doubt, however, that the construction of the path or the house or both led to the landslide.

That could have been Gaia’s revenge.

Ravindra Pande (http://savethehills.blogspot.in/2012/04/nainital-landslide-town.html) has recently (April 2012) described Nainital as a landslide town noting that landslides continue to occur with three major ones occurring after 1880 which were caused by ill-conceived urban growth with their being about 25 instability incidences in 10 sq km area.

The landslides shown in Fig 1 and almost in all other images in the internet of mountain landslides may be clearly associated with road building. This aspect is what was asserted by Sunderlal Bahuguna in his early Chipko movements. My wife and I once walked with him --- we ended up walking all the way to Gangi --- along with an assortment of then budding and now prominent environmentalists, who made themselves comfortable in the luxury and hospitality of Sunderlalji’s Shilyara ashram. They did not venture outside as they were warned of the dangers of wild animals. My wife and I had come along more to see the Himalayas than to environment. So we went with Sunderlalji’s daughter to the then virgin rhododendron forests on the way to Gangi.

There were no motor-able roads in these rhododendron forests; just walking paths. There was also no landslide. Gaia was happy.

I should have discussed what led to the flash floods of the 2013 disaster. For this, I require a little more thought on the fragile nature of the ecosystem. I am examining the sand-pile model where a fragile system may be sustained in a self-organized critical state. In such a state a slight disturbance can lead to long-range catastrophes that stabilizes the system but again to another critical system.

Gaia and the Pilgrim’s Choice

Why the pilgrimage?

One could just say: “because it is there”!

There used to be times when only the brave, mainly those who trusted Gaia enough to be fearless, even if they were poor in health and wealth, who would take the pilgrim’s route to go to, what they thought, would be the abode of the gods. They undertook the trek up the hills because their god had many a time answered their prayers.

The pilgrims walked in those earlier days with their bundle on their heads. I have seen them. For a little while I may have even walked with them. It is not easy for us plainsmen to have walked on the hills. The pilgrims walked not because they had a choice, but because they wanted to. There is no penance without working for it.

Or, maybe, May-June is the time of the Dasar festival when the new moon is the brightest, when the water in the rivers are full, and they float lamps along the river. This is the time Ganga descends in mythology, and the time that the monsoon opens up in meteorology. This is the pilgrim’s time for a pilgrimage. It is not a pilgrimage to any particular god but perhaps to energy, the goddess Shakti, and her obeying consort, Shiva. Gaia could not be happier!

Where men are gods?

It is good to remember that the Uttarkhand area are not peopled by people from the plains. They have Tibetan (Kipling would call them Esquimaux) or Khasi features. The region around Nainital itself was called Khasi-desh. The Khasis still constitute nearly 40-50 percent of the population (as Khasi Brahmins or rajputs). These are people who are from the hills, who are used to the hills, are comfortable in the hills. They would not require vehicles to travel ten-twenty miles in a day. They do not require roads the way people from the plains do. 

Gaia, who looks after all her people, would probably like the Hill-people to live on their own terms, terms with which they have been born with and terms that know how to walk the rugged terrain without leveling their paths.

Rudyard Kipling, through the sensitivities of Kim (and Perhaps Tom Alter), a plainsman, would make this distinction. I have been reading Kim lately, especially Chapter 14. The part I am quoting from this chapter is quite long. It saves me the trouble of being a fraction as clear. Kipling would write in Kim:-

Kim had all a plainsman's affection for the well-trodden track, not six feet wide, that snaked among the mountains; but the lama, being Tibetan, could not refrain from short cuts over spurs and the rims of gravel-strewn slopes. As he explained to his limping disciple, a man bred among mountains can prophesy the course of a mountain-road, and though low-lying clouds might be a hindrance to a short-cutting stranger, they made no earthly difference to a thoughtful man. Thus, after long hours of what would be reckoned very fair mountaineering in civilized countries, they would pant over a saddle-back, sidle past a few landslips, and drop through forest at an angle of forty- five onto the road again. Along their track lay the villages of the hillfolk - mud and earth huts, timbers now and then rudely carved with an axe - clinging like swallows' nests against the steeps, huddled on tiny flats half-way down a three-thousand-foot glissade; jammed into a corner between cliffs that funnelled and focused every wandering blast; or, for the sake of summer pasture, cowering down on a neck that in winter would be ten feet deep in snow. And the people - the sallow, greasy, duffle- clad people, with short bare legs and faces almost Esquimaux - would flock out and adore. The Plains - kindly and gentle - had treated the lama as a holy man among holy men. But the Hills worshipped him as one in the confidence of all their devils. Theirs was an almost obliterated Buddhism, overlaid with a nature-worship fantastic as their own landscapes, elaborate as the terracing of their tiny fields; but they recognized the big hat, the clicking rosary, and the rare Chinese texts for great authority; and they respected the man beneath the hat. 

Kipling would write further:-

At last they entered a world within a world - a valley of leagues where the high hills were fashioned of a mere rubble and refuse from off the knees of the mountains. Here one day's march carried them no farther, it seemed, than a dreamer's clogged pace bears him in a nightmare. They skirted a shoulder painfully for hours, and, behold, it was but an outlying boss in an outlying buttress of the main pile! A rounded meadow revealed itself, when they had reached it, for a vast tableland running far into the valley. Three days later, it was a dim fold in the earth to southward.

'Surely the Gods live here!' said Kim, beaten down by the silence and the appalling sweep and dispersal of the cloud-shadows after rain. 'This is no place for men!'

Kipling must have meant the men from the plains when he said “this is no place for men”. Gaia protects them by landslides even if the mountain people may not like it that way.

By all indications the early peopling of the Himalayas were by hill people such as the bon people from Tibet who occupy Bhot-land at the border with Tibet. Some of the family names, such as Bhotia and Bhutia are said to be derived from the bon people. In the lower Uttarakhand, like the Kumaon, the features could be of the Khalsa kind. In the Figure 4 below the features of the people from Kumaon (left, probably three generations of women) become closer to those from the plains: those from Bhotland (Fig 4, right) have features closer to Tibetans.

The gods of the Uttarakhand are then those worshipped by the native mountain people of Uttarakhand. If they are also the gods of some people from the plains, then these people have memories of the Himalayas. 

It is said that people from the plains fled to the hills to escape the Muslims. There does not seem to be ancient Muslim shrines in the Uttarakhand.

Maybe the hill people benefitted (or thought so) by the visit from the planes. My recent internet reading informs me that the Bahugunas are Bannerjees who came there 800 years ago and helped the local king to solve his problems. They became known as Bahugunas because of their wisdom in many areas. Despite their 800 years or so in the hills, I have a suspicion that they have the mentality of plainsmen.

Uttarkhand also does not seem to be an important place in our mythologies such as Ramayana except, perhaps,  for Hanuman and the Sanjeevani episode. The Himalayas are more the abode of Shiva/Shakti worshippers. After all, the Dusshera festival of worship of Durga and her family in October-November --- when rivers freeze, farming ceases, and families reunite --- is most widely observed in Nepal and Bengal. The hill shrines of the Himalayas close.

Temple of the Gods

A little bit may be learnt from the style of the Himalayan temples. It is said that Shankaracharya built these temples. Little is known with certainty about Shankaracharya’s life. I discount these tales. If at all, one may concede that he or his followers may have helped in installing the yoni-lingam symbol there. Even those symbols seem to be fairly recent.

I may like to think instead that Shankaracharya’s philosophies or those attributed to him originated from Tibet itself. I have little evidence for that. It is said that some of our early yoga gurus learnt their philosophies there.

It is a moot question to me now of whether the temple arcitcetures also evolved from some of the Uttarakhand temples.

The temples in Uttaranchal were usually said to be made in Nagara style of architecture or the Garhwali Style of architecture. Some of the more popular panch-kedar temples are shown to the left of Fig 5. In the inset of this figure, a late nine-teenth century painting of the Bhimeshwar temple built on the edges of the Bhimtal lake in the Kumaon hills is shown. The Nagara architectural style is simple but striking with its tall curvilinear spire ‘Sikhara’ with an ‘Amalaka’ (capstone) on top of the spire. The Garhwal temples do not usually have the Amalaka but have a tiled roof resting on pillars. The function of this tiled roof is not clear to me. It could have been a rest/bed room or a place to escape from when there is a flood or when there are fear of marauders and wild animals, Sometimes the pillared structure on top has no base (especially if the shikara is small) and seems to be just placed on the stone shikara as in the Siva temple at Lakhamandal (Fig 5, bottom right). This temple also seems to have an an Amalaka typical of the classical Nagara style.

The original model for such temples could be the Mahasu devta temple (Fig 5, top right) at Hanol village near Chakrata This temple includes the room with a tapering roof in front of shikara at ground level. Such a structure is seen in almost all the temples.

The tapering brass kalash pinnacle is typical of all the -nath temples in Garhwal as seen from Fig 5 (click to expand).

Wikipedia writes:-

Architecturally Mahasu Devta Temple at Hanol is one of the rarest examples of perfect and harmonious blend of stone and wooden structure to form one composite grand edifice. The sanctum proper is a pure stone shikhara in classical naga (Nagara?) style. The whole wooden structure is covered with a high pitched slated pent roof surmounted by a two-tiered conical canopy over it on which a gracefully tapered kalash pinnacle stands.

The panch-kedar temples, including Kedarnath, are therefore likely to be of hill- or tribal- origin in style. They are supposed to be built around 8^th-10^th century AD when stone technology to build temples was evolving. The earliest Nagara style temples in Orissa started only around 8^th century.

An early structure is the Lakhamandal structure near Chakrota. The area where this temple is found is said to be a tribal land where polyandry and polygamy is practiced. Following arguments which seem to be obvious to some, if not to all, the Pandavas of Mahabharata followed the same practice and therefore this should be Pandava land. The temples had to be built by the Pandavas. Could these legends be the basis that the Garhwal hills are associated with the Pandavas of Mahabharata?

It is also not clear when these temples became Shiva-Shakti temples.

 

All this does not rule out the possibility that the Pandavas were actually tribals of the Himalayas. It also does not rule out the possibility that the colonization of Uttarakhand by people from the plains is a recent phenomenon. Some say, it started with Brahmins fleeing from the moghul invaders. Some will say that it started with the British who wanted a more malleable populace rather than the proud hill-people. After the princely state of the Garhwals was roundly thrashed by the Gorkhas from Nepal, they got back their rule after ceding two-thirds of their earlier kingdom to the British. West Garhwal became the Kingdom of Tehri and thus the legend that the kingdom of Tehri always remained outside British colonial rule.

 

So when did the Garhwals become a pilgrimage spot for the people from the plains?

 

I don’t think I could even attempt an answer to this. It won’t stop me from attempting an answer, though.

 

The Tibetan bon-worshippers are all around the Mansarovar lake, most sacred lake for Hindus. The pre-Buddhist Bon worship is animistic which worship natural elements with the tenet that there is life/spirit in everything animate/inanimate --- heaven, earth, sun, moon, mountains, rivers, thunder, lightning, hail, fog, birds, and animals.

 

All this is quite consistent with the Shiv,  Shakti, Ardhanareshwar concepts. It is therefore possible to think that the pilgrimage from the plains to the hills must have been from the memories of prayers in their early Himalayan temples. For such worship a symbolic rock is sufficient even if later worshippers should have given symbolic shape by installing the man-women (Ardhanareshwar?) union in a more familiar lingam-yoni symbols in Shiva temples.

 

Epilogue. Death in the Himalayas.

It is difficult to think of Death in the Himalayas as part of the grander scheme of Ardhanareshwar or Gaia. It helps in resettling to the tragedy.

 

I have had a personal loss in the Himalayas of May-June 1986. It snowed unexpectedly heavily in Gangotri when I visited with my parents and my sister’s family. The first snows were wonderful and enjoyed by my parents. The parents were extremely happy with this experience (see photo below).

 

My wife, Lalitha, had gone for a trek to Gangotri with her sister, Sharada’s, family. It snowed more heavily after they left and there was no news from them for some time. There were no mobiles at that time. We were worried. There were many pilgrims. They walked in the snow in their thin saris and almost barefoot when they ploughed through the snow in their flimsy slippers. We saw the pilgrims come back with all the composure that we thought were reserved only for the gods. We realized the power of the pilgrimage.

 

Looking back at the pictures (below left) of Laltha’s return I noticed that the style of the Gangotri temple to be the same as in Fig 5. I had not noticed this earlier. The more frequented temple is adjacent to this structure (right of photo below). I hope that future reconstruction of the Himalayan temples will not take the Gangotri route.

The snow continued for some time. We were stuck at Joshimath because of landslides for another few days. My father felt the cold badly. He developed breathing trouble. We made some logistic mistakes trying  to get back. My father passed away in Shilyara of, what we learnt later, an oedema of the heart.

 

My father did not want to die there. Gaia helped us reconcile to his death if only because we were told that that gods die there.

 

The Gods also really require being listened to.

 

I don’t know what collective wisdom the three heads of the Trimurti, Brahma, Visnu and Siva will take when they look upon the damage brought to the Earth they helped create and maintain. They do not get enough appreciation from mankind. I am reminded of a cartoon from Ananth (http://www.hindu.com/lf/2004/11/19/stories/2004111913620200.htm, for a review) Shankar’s book of Cartoons called “Bisi, busy Bangalore” 

 

Hundred Years of the Bohr Atom. Part III: The road to Bohr’s Model

“ … children at school should not be introduced to quantum phenomena through any description of the atom which includes Bohr’s orbits” Mott, Contemporary Physics, 1962

With that qualification from the very reverend Rev Sir Neville Mott, Nobel Laureate 1977, it seems necessary for me to cite what Bohr himself said:- 

“Every sentence I utter must be understood not as an affirmation, but as a question.” — Bohr

It is the possible questions in Bohr’s postulates that we need to be interested in if not in the model itself.

This series of blogs was actually started with the intention of it being my beginner’s interpretation of the method behind Bohr’s model for the atom. Why it was necessary? How it evolved? In the next blog I hope to deal with how it impacted the development of quantum theory as applied now?

As dwelt with in my previous blog (Part II), quantum theory actually began with Planck (quantum of action) and was extended by Einstein (light quantum). The nature of Bohr’s contributions a hundred years ago is directly based on the work of these two giants. However, it has to be remembered that the impact of Bohr’s work was so great that the Nobel prize (1922) was awarded to him within nine years of the publication of his paper. Planck would have to wait 18 years after his 1900 publication; Einstein would have to wait 20 years. Despite this success, Bohr’s model has been the only one to have been almost completely ignored  (see left of figure below) in recent times mainly because of its failure to be generally applicable to atoms other than hydrogen-like atoms and its failure to be applicable to the simplest molecule, the hydrogen molecule. But then the Nobel committee has its own ways and Bohr’s success must be taken as a lesson in the way science is sometimes recognized. 

In the latter part of his life (right of above figure) Bohr worked mainly on the philosophical aspects of Quantum Mechanics most important of which perhaps is the “... postulation that the act of observing something affects the results of that observation”  as well as the wave particle duality. There is much to admire about Bohr and I would love to read Ottavani and Purvis’s illustrated comic book “Suspended in Language” from which two cartoons have been taken in the right of the figure above. As a Jew, he escaped from Nazi Germany in the bomber hold of an allied aircraft. He was also in the secret Manhattan project where he “...soon became a security concern, however, since his philosophical and globalist nature drove him to encourage open sharing of nuclear information with the Russians.”

Around a hundred years ago, Planck’s evidence for the quantum of action must have been the immediate scientific quantity seeking an application. Bohr indeed starts his first paper “On the Constitution of Atoms and Molecules” by noting the “... inadequacy of the classical electrodynamics in describing the behaviour of systems of atomic size...” and that “... it seems necessary to introduce in the laws in question a quantity foreign to the classical electrodynamics, i. e. Planck's constant, or as it often is called the elementary quantum of action … .“ Bohr acknowledges that the “... general importance of' Planck's theory for the discussion of the behaviour of atomic systems was originally pointed out by Einstein...”.

The pre-Bohr history on application of Planck’s constant to a model for the atom seems to be important in understanding the way Bohr applied his quantum model for the hydrogen atom even though he had many shoulders of others to stand upon.  It nevertheless marks the origin of the quantum chemical model for the structure of atoms which now stands in his name,

Early contributions to the development of Bohr’s model.

Bohr has acknowledged by name the contribution of Arthur Eric Haas, Bohr writes “The agreement as to the order of magnitude between values observed for the frequencies and dimensions of the atoms, and values for these quantities ... was first pointed out by Haas*, in an attempt to explain the meaning and the value of Planck's constant on the basis of J. J. Thomson's atom model.”  The remarkable aspect of Haas’s work in 1910 is that it was before Rutherford’s model.(1911). Haas’s model had a heavy positively charged nucleus with extranuclear electrons and was based on alpha-particle scattering.

Haas’s aim, it seems, was to produce a simple model for a Planck resonator and the one-electron case was the simplest. It need not have been the hydrogen atom. Haas actually changed Thomson’s plum pudding model where electrons are fixed in space and instead modelled a negatively charged electron as revolving around the surface of the atom with one energy quantum.

The important difference with Haas is that he considered the spatial dimensions of the atom to be fundamental, instead of the Planck’s constant.  Using the constant of Balmer’s equation, Haas also correctly derived the Rydberg constant from the action quantum h, the velocity of light c, and the fundamental magnitudes of the electron, e and m. He achieved this relation by a very formal second hypothesis, namely, that the frequency derived from his quantum rule corresponds with the constant of Balmer’s equation. From this size Haas obtained the value of the Rydberg constant within a numerical factor of eight. The value of Planck’s constant could then be expressed it in terms of the mass and radius of the hydrogen atom.

Arthur Erich Haas is a remarkable figure. Born as a Bohemian, he stumbled across Thomson’s earlier work while working on his thesis on history of science and the went on to write a treatise on Physics. Haas later went on to become a founding father of cosmology believing, like a true Christian --- and other seemingly simple folks --- the age of the universe to be finite. More interestingly (at least for me) Haas was among the first to propose that the total energy of the universe is zero having both positive and negative contributions.

Around this time, Bohr was in Copenhagen completing the defence of his doctoral thesis on the nature of electrons in metals. This interest was based on Thomson’s discovery that the spooky glow of cathode-rays emitted from metal electrodes were not disturbance of the aetherial medium as one expected, but were actually particles (which were later called electrons). Because of this interest in electrons in metals, Bohr would naturally use his award of a stipend from the Carlsberg foundation to join Thomson’s group in the prestigious Cavendish Laboratory at Cambridge. It has been well documented that Bohr was disappointed by Thomson’s lack of interest in Bohr’s interest in Thomson’s model.  Bohr became more attracted to the idea of joining Rutherford at Manchester.

When Bohr joined Rutherford’s group around 1912, phenomena associated with scattering of charged particles when impacted on matter was of natural interest, with the focus being naturally on what more information can be obtained on the constitution of matter from way Rutherford’s model of the atom. It is this interest that gave rise to powerful new results. These included, Geiger and Marsden’s crucial results with alpha particle scattering that confirmed Rutherford’s theory; Van den Broek’s results on atomic number, Z, and nuclear electrons; Moseley’s association of frequencies of X-ray radiation with atomic number; Soddy’s discovery of isotopes of elements and so on. All of these experiments are the jewels in Rutherford’s crown that followed directly from his model for the atom. The most shining theoretical jewel at that time was Bohr’s planetary model for the hydrogen atom, which precedes chronologically or is contemporaneous with the discoveries just mentioned.

It must have been “bliss in that dawn to be alive” in Rutherford’ laboratory. In Spangenbrg and Moser’s book “Niels Bohr: Atomic Theorist” we have this description

Each afternoon in the lab, work was set aside for tea. Rutherford would come in, sit down and talk. The lab group avidly discussed politics and sports and, of course, work. Ideas always were exchanged freely at these daily get-togethers. So much was happening in physics that no one was afraid that someone else would take his idea and publish it first. There were plenty of vital topics for everyone.

Bohr was little motivated by discussions with Rutherford. Instead, Bohr’s theoretical/mathematical background drew him to Charles Galton Darwin, an unusual man who later, at sixty, wrote a scientific treatise on the evolution in “The Next Million Years”. He was perhaps burdened by the reputation of his grandfather who had his treatise on the Origin of Species during the previous Million Years. We cannot really judge the merits of CGDarwin’s book until a million years have passed since it was written!

The Chapter on Material Conditions in this book, is perhaps the more easily judged from contemporary results. CGDarwin considered various environmental and energy issues that is relevant. He reveals his views on, what seems to be, the empiricism of theoreticians. He writes (about the various ages of the earth) “…theorists claim to have given an explanation on astronomical grounds for the recent four ages—but then if there had been five, might they not have discovered a different but equally cogent reason for there having been five?” This comment becomes relevant when one considers, say, the recent debate on the status of Pluto as a planet from both astronomical and astrological considerations. The more notorious recent example (perhaps not so recent) for the empiricism of theoreticians must be, of course, the theories for high-temperature superconductivity! During Darwin’s time also, there were various attempts to describe atomic structure that must have hampered his own research, since it could have depended on such knowledge.

Galton Darwin was set by Rutherford to make a theoretical model for the trajectory of α-particles when traversing matter. Darwin assumed that the a-particles lost velocity because of transfer of their kinetic energy to the electrons of the atoms during collisions of the atoms. The electrons were treated as free particles and the a-particles acted by forces varying inversely as the square of the distance apart. Consequently Darwin’s results depended on the size of the atom and the charge on the nucleus. Darwin was found that his formula would hold for the hydrogen atom if it had only one electron. There was no clear evidence for it at that time. 

Bohr’s first 1913 paper On the Theory of the Decrease of Velocity of Moving

Electrified Particles on passing through Matter in Philosophical Magazine built on CGDarwin’s work. He stressed the importance of forces “ … by which the electrons are kept in their positions in the atoms. Under the influence of these forces the electrons will have a sort of vibratory motion if they are disturbed by an impulse from outside.” This seems to be the crucial point in Bohr’s modification of Darwin’s approach. Thus, as Mott writes, “…quantization applies to any movement of particles within a confined space, or any periodic motion, but not to unconfined motion such as that of an electron moving in free space or deflected by a magnetic field.”                              

The concept of Planck’s constant or the elementary quantum of action does not appear in Bohr’s first 2013 paper “On the theory of the decrease of velocity of moving electrified particles on passing through Matter” although he borrowed concepts from Planck’s resonator. However, in the first of his 1913 papers “On the Constitution of Atoms and Molecules” Bohr, like Haas before him, would use Planck’s quantum of action:- “Now the essential point in Planck's theory of radiation is that the energy radiation from an atomic system does not take place in the continuous way assumed in the ordinary electrodynamics, but that it, on the contrary, takes place in distinctly separated emissions, the amount of energy radiated out from an atomic vibrator of frequency n in a single emission being equal to thn, where  t is an entire number, and h is a universal constant”. Such forces “… will materially alter the motion of the electrons during the collision, and consequently the loss of energy of the particle, if the time of vibration of the electrons is of the same order of magnitude as the time …  the particle takes to travel through a distance of the same order of magnitude as the shortest distance apart of the electron from the path of the particle.” The decrease in velocity “… will depend purely on the frequency of the electrons and the velocity of the particles,”

Bohr acknowledged that such a theory borrows from the electromagnetic theory of dispersion when the frequency of the light is replaced “by the different times of collision of particles of different velocities” .Bohr realized that effects due to changes in the “frequency” (binding energy) of the “vibratory” electrons would be more rapid than the loss of velocity of “moving” (free) particles one could get “some more information about the internal structure of the atoms.” Bohr then concluded “If we adopt Rutherford's conception of the constitution of atoms, we see that the experiments on absorption of a-rays very strongly suggest, that a hydrogen atom contains only one electron outside the positively charged nucleus.”

Despite his association with Niels Bohr (see below), CGDarwin does not mention the word “quantum” in his future million years. CGDarwin writes that ordinarily “… scientific progress means the discovery of yet more exact effects produced by exact causes, and … that the cause-and-effect relation is the sole idea in the scientific method. He then emphasized that “… a very different new type of procedure is connected with the principle that the result of a great number of chances may be far more certain than the result of a few. … This newer type of reasoning is connected with the principle of probability.” CGDarwin has the Boltzmann-Planck-Bose models in mind.

Planck’s statistical distribution model for the scattering of light would help Bohr improve upon Darwin’s model for the scattering of a-particles by matter from which he came to the very important conclusion of there being only one electron in the hydrogen atom. Once this was dealt with, the theoretical problem of the hydrogen atom had no electron-electron interactions to contend with. Further, this single electron character of the hydrogen atom allows Bohr to assume “that the orbit in question is circular … for systems containing only a single electron.” For those few working on the structure of atoms at that time this would have been a blessing. Bohr would be the first to realize this and the first to exploit this to account for a structural model for the one-electron hydrogen atom. 

From distinct allowed rotation to the idea of quantized angular momentum seems to be a logical step. It was Nicholson in 1912 who suggested that the angular momentum assumed values which were integral multiples of h/2π.

”If, therefore, the constant h of Planck has, as Sommerfeld has suggested, an atomic significance, it may mean that the angular momentum of an atom can only rise or fall by discrete amounts when electrons leave or return. It is readily seen that this view presents less difficulty to the mind than the more usual interpretation, which is believed to involve an atomic constitution of the energy itself.”

                                                                                 Nicholson (1912)

Mott, writes in his 1962-Contemporary-Physics article

Bohr-as every schoolboy knows-made the assumption that the angular momentum L should be given by L = nh/2p  where n is an integer. The factor 2p, turning up as it does, often seems arbitrary, and I do not think it can be explained without quantum mechanics. Bohr introduced it to obtain agreement with experiment for the energy levels of hydrogen.

Bohr’s first paper on the structure of the atom

One of the first lines of the first part of his paper in which he makes general considerations on the binding of electrons by positive nuclei, Bohr writes:-

Let us at first assume that there is no energy radiation. In this case the electron will describe stationary elliptical orbits.

It is the concept of stationary orbits and not quantization that seemed to be the most important step. In this Nobel lecture for “… a formulation of the principles of the quantum theory that could immediately account for the stability in atomic structure and the properties of the radiation” he states:-

(I). … there exist a number of so-called stationary states which, in spite of the fact that the motion of the particles in these states obeys the laws of classical mechanics …, possess a peculiar, mechanically unexplainable stability, of such a sort that every permanent change in the motion of the system must consist in a complete transition from one stationary state to another.

(2). … in contradiction to the classical electromagnetic …, a process of transition between two stationary states can be accompanied by the emission of electromagnetic radiation, which will have the same properties as that which would be sent out according to the classical theory from an electrified particle executing an harmonic vibration with constant frequency. This frequency v has, however, no simple relation to the motion of the particles of the atom, but is given by the relation hv = E’ – E”, where h is Planck’s constant, and E’ and E” are the values of the energy of the atom in the two stationary states that form the initial and final state of the radiation process. Conversely, irradiation of the atom with electromagnetic waves of this frequency can lead to an absorption process, whereby the atom is transformed back from the latter stationary state to the former.

Although Bohr agreed with Nicholson that from Planck’s theory the radiation from an oscillator “is sent out in quanta” such a radiation cannot be “homogeneous … for, as soon as the emission of radiation is started, the energy and also the frequency of the system are altered.” This statement is perhaps a quantum equivalent of the classical argument that as electrons move about the nucleus it would lose energy and would spiral into the nucleus.

In order to obtain the binding energy of the hydrogen atom Bohr had to make two important assumptions. The first of these is that “… the stationary states can discussed by help of the ordinary mechanics …”. In a classical model, the electron’s acceleration in the hydrogen atom, is the centripetal acceleration, v²/r , and the only force (e²/4pe₀r²) acting on the electron is the Coulomb attraction of the proton. From Newton’s second law mv²/r = (e²/4pe₀r²). Since the kinetic energy, K, for a classical system is mv²/2 and the potential energy, U, for a negatively charged electron and a positively charged proton is – e²/4pe₀r. we obtain from Newton’s second law, K + U/2 = 0. In classical mechanics this result is obtained from the virial theorem. The total energy E = K + U = -e²/4pe₀r. In classical mechanics the virial theorem cannot have an absolute validity, but will

only hold in calculations of certain mean values of the motion of the electrons. What is necessary in order to account for spectroscopic facts is that “in obvious contrast to the ordinary ideas of electrodynamics” “one need not distinguish between the actual motions and their mean values”.

The second point is that the transition between different stationary states cannot be treated classically. Here, the transition leads to emission of a homogeneous radiation following Planck with hv = E’ – E”. In order to obtain these energies, one requires a knowledge of the radii, r’ and r”, of the two states between which the transitions take place. Bohr then used the term of a “permanent” state for the “the one among the stationary states during the formation of which the greatest amount of energy is emitted.” This “permanent” state is now referred to as the ground state. The calculation of the energy required a knowledge of the angular momentum.

Bohr acknowledges Nicholson’s effort in showing “… that the ratios between the wave-length of different sets of lines of the coronal spectrum can be accounted for with great accuracy by assuming that the ratio between the energy of the system and the frequency of rotation of the ring is equal to an entire multiple of Planck's constant.” Bohr would introduce quantization by stating that “… the angular momentum of the electron round the nucleus in a stationary state of the system is equal to an entire multiple of a universal value, independent of the charge on the nucleus.” It may be argued that such a quantization of angular momentum is conceptually different from Planck’s quantization of energy. However, the quantization of angular momentum is equivalent to the quantization of energy.

The “entire multiple” (integer) by which the angular momentum is quantized was given the notation, t, by Bohr and it is now known as the principal quantum number. For the present we continue to use Bohr’s notation, t. The “permanent” or ground state would correspond to t = 1, which has the lowest energy and is mainly occupied at low temperatures. The radius of the “allowed” (t = integer) stationary states was obtained as what is now known as the Bohr radius. For the hydrogen atom, the Bohr radius, a_H, for the ground state (t  = 1) is given by a_H = (h/2p)²/me². In general, a_H(t) = t²(h/2p)²/me² From the virial theorem we then obtain the energy E_(t=1) for the ground state as E_(t=1) = ­-e²/2a_H. In general, E_t = -me²/2a_H(t) = -2p²me⁴/2t²h²,

If now we suppose that the radiation in question is homogeneous, and that the amount of energy emitted is equal to hn, where n is the frequency of the radiation, we get

Et₂ - Et₁ = 2p²me⁴/2h²(1/t₂² -1/t₁²)

or the frequency, v, of the “homogeneous” radiation is given as

v = (Et₂ - Et₁)/h = 2p²me⁴/2h³(1/t₂² -1/t₁²)

Bohr then concludes

“We see that this expression accounts for the law connecting lines in the spectrum of hydrogen. If we put t₂ = 2 and let t₁ vary, we get the ordinary Balmer series. If we put t₂ = 3, we get the series in the ultra-red observed by Paschen and previously suspected by Ritz. If we put t₂ = 1 and t₂ = 4, 5, . . , we get series respectively in the extreme ultra-violet and the extreme ultra-red, which are not observed, but the existence of which may be expected.”

Bohr commented also

It may be remarked that the fact, that it has not been possible to observe more than 12 lines of the Balmer series in experiments with vacuum tubes, while 33 lines are observed in the spectra of some celestial bodies, is just what we should expect from the above theory. According to the equation (for a_H(t)) the diameter of the orbit of the electron in the different stationary states is proportional to t². For t = 12 the diameter is equal to 1.6 x 10¯6 cm., or equal to the mean distance between the molecules in a gas at a pressure of about 7 mm. mercury; for t = 33 the diameter is equal to 1.2 x 10¯5 cm., corresponding to the mean distance of the molecules at a pressure of about 0.02 mm. mercury. According to the theory the necessary condition for the appearance of a great number of lines is therefore a very small density of the gas …

All this would strongly suggest that the more important immediate impact of Bohr’s contributions has been in accounting for the spectral lines of the hydrogen atom. He was thought at that time to be a spectroscopist explaining spectral lines such as the Balmer lines. Even as a spectroscopist, Bohr was not the first to invoke quantization. In his Nobel lecture Bohr acknowledges Bjerrum’s contributions on spectra of rotating molecules in which Bjerrum “… emphasized the fact that the effect should not consist of a continuous widening of the lines such as might be expected from classical theory, which imposed no restrictions on the molecular rotations, but in accordance with the quantum theory he predicted that the lines should be split up into a number of components, corresponding to a sequence of distinct possibilities of rotation. … and the phenomenon may still be regarded as one of the most striking evidences of the reality of the quantum theory …” (From Bohr’s Nobel lecture).

Bohr’s derivation of the formula for the spectral lines of hydrogen atom is accurate. To date, it is the only quantum mechanical result that gives accurate values using first principle arguments. Later developments in wave mechanics through Schrödinger’s wave equation, do not give such striking agreements from completely ab-initio calculations. The formula is identical with that obtained by wave mechanics.                                        

Bohr is nevertheless historically associated with the initiation of a quantized approach to electronic structure of atoms that now dominates modern theoretical thinking, even if it is now in another Schrodinger’s-wave-function way. Bohr’s model would have many shortcomings. One of the earliest was when Rutherford would draw Bohr’s attention to the Stark effect which showed a splitting of lines in the presence of an electric field. This effect could not be explained, much as Bohr tried, using non-elliptical electron orbits that is imposed by Bohr’s use of t (later known as the principal quantum number, n) alone.

Sommerfield (around 1916) extended Bohr’s model to include elliptical orbits and magnetic fields he was able to model other quantum numbers such as the angular momentum quantum number, l (- 0, 1, 2, … (n-1)), and the (2l + 1) magnetic quantum number, m_l (= -l, -(l -1), …(l-1), l), and Pauli added the spin quantum number, m_s to complete the quantum numbers of the so-called old quantum theory. Such quantum numbers were mainly designed to explain the spectral lines of atoms, before Schrödinger’s wave equation (1926) became established as the new quantum mechanics.  What is important is that the use of such quantum numbers does not necessarily require Schrödinger’s wave equation as a pre-requisite.

The various quantum numbers are a consequence of the Bohr-Sommerfield model which, with its various quantum numbers, gives some validity to treating atoms like a microscopic solar system --- each electron keeping its place through its own unique identification card (its adhaar card, that we Indians like to complain about) consisting of various quantum numbers.

It was Fermi who first examined this aspect in detail. In the translation (arXiv:cond-mat/9912229v1 [cond-mat.stat-mech] 14 Dec 1999) of his Italian paper) of his 1926 paper On the Quantization of the Monoatomic Ideal Gas (Rend. Lincei, 3,145-149 (1926)) Fermi writes “It is necessary to admit that we must add some complements to Sommerfeld’s rules, in the case of systems, … in which the elements are not distinguishable from each other …like … atoms heavier than hydrogen … containing more than one electron. The fact that “…the K ring is already saturated when it contains two electrons, and in the same way the L ring is saturated when it contains 8 electrons, was interpreted by Stoner,[ E. C. Stoner, Phil. Mag. 48, 719 (1924)] and even more precisely by Pauli,[ W. Pauli, Zs. f. Phys. 31, 765 (1925)]. … To realize this fact, it is sufficient to assume that in the atom there can not be two electrons with the orbits described by the same quantum numbers; in other words it is required to admit that an electronic orbit is already ”occupied” when it contains only one electron.” It was this that gave the Pauli exclusion principle and then the complete Aufbau (building-up) principle from which the electronic configuration of atoms  could be obtained and the periodicity of the periodic table could be obtained. It is, however, to Bohr’s credit that it was he who first introduced the concept of an Aufbau principle based on two quantum numbers, principal and subordinate.

Bohr’s idea of stationary states as states --- such as those of a hydrogen atom --- is that in which an electron remained in the same orbital state for all time, in contrast to that in classical physics which would require the orbiting electron to radiate away its energy and spiral into the nucleus. Although Bohr’s original concept is now no longer appropriate, the notion of a stationary state remains a valid one. The stationary states of such quantum systems do not change in time in the sense that the probabilities of outcomes of a measurement of any property of the system is the same no matter at what time the measurement is made. The cartoon below on self-reference effect (“tendency of people to effectively recall information about themselves”) probably represents one view of this stationary state.

Bohr’s stationary states really follows Hamilton's principle of classical physics which means that of all the possible equations of motion of a mechanical system between two time intervals, the motion will occur along the curve that gives a stationary value (extreme value of a function where the derivative is zero) to the action integral which is the integral of the Lagrangian (difference between kinetic and potential energy) over the time interval. It is this Hamilton’s principle that was used by Schrödinger in developing his theory for “undulatory mechanics” (see An undulatory theory on the mechanics of atoms and molecules” Schrödinger, 1926, Phys. Rev.). The Hamilton principle comes from the “theory of propagation of light in a non-homogeneous medium, which... became the starting point for his (Hamilton’s) famous theories in pure mechanics.”

The philosophies on quantum mechanics that arose from Bohr’s model of stationary states follows in the next blog.