Round Earth: The Proofs

What is the evidence for a round Earth?

In this post, we explore some of the evidence for proving that the Earth is indeed spherical in shape (if not a perfect one), and not a flat one. Though in the current age we can all point to the images of Earth taken from space  (like the one shown below)

In the age of satellites is easy for us to dismiss the doubting minds who think that the Earth is not flat. But this was always not so. Apart from the evidence from the space age, people in the past had good evidence and arguments for believing that the Earth was indeed spherical in shape and not flat or any other shape. Somehow this misconception that all ancient people considered that the Earth was flat, was generated in nineteenth-century science books.
earth

Ancient evidence

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It is commonly believed that people till very recently believed that the Earth is flat and that some European explorers, by circumnavigating the Earth, proved that it was round. But this is not correct. Ancient Greeks already knew about the spherical shape of the Earth, and it forms the basis of many cosmological models that they built. This, in turn, had implications for the philosophical worldview of the ancient
Aristotle presents us with one of the first evidence for the roundedness of the Earth. For the ancient Greeks, the circle and the sphere presented the perfect form in nature. This was also tied to their worldview in which the celestial and terrestrial was demarcated from each other. The celestial bodies, which included the planets and stars were supposed to be perfect. There were seven planets known to the ancients, which included the Sun and the Moon. The planets were supposed to be spherical themselves revolving with a constant speed in circular orbits around the Earth. One of the core assumptions was that the heavens are unchangeable. So anything that was considered celestial was by definition (a) perfect (spherical or circular), (b) unchangeable (constant). So any mechanism that explained celestial phenomenon had to include these two concepts.
 
The cosmology of the ancient Greeks then was built upon these basic assumptions which were non-negotiable for them. This lead to the formation of various models based on the basic theme of a fixed Earth and planets on circular orbits moving constant speeds. Due to these assumptions and also due to some observed phenomena, led to the conclusion that Earth should also be indeed spherical.
Let us look at the arguments given by Aristotle in this regard. This is from Book II of On the Heavens.

The shape of the heaven is of necessity spherical; for that is the shape most appropriate to its substance and also by nature primary.
Part 11
With regard to the shape of each star, the most reasonable view is that they are spherical. It has been shown that it is not in their nature to move themselves, and, since nature is no wanton or random creator, clearly she will have given things which possess no movement a shape particularly unadapted to movement. Such a shape is the sphere, since it possesses no instrument of movement. Clearly then their mass will have the form of a sphere. Again, what holds of one holds of all, and the evidence of our eyes shows us that the moon is spherical. For how else should the moon as it waxes and wanes show for the most part a crescent-shaped or gibbous figure, and only at one moment a half-moon? And astronomical arguments give further confirmation; for no other hypothesis accounts for the crescent shape of the sun’s eclipses. One, then, of the heavenly bodies being spherical, clearly the rest will be spherical also.

In Part 13 of the book Aristotle talks about the shape of the Earth.

There are similar disputes about the shape of the earth. Some think it is spherical, others that it is flat and drum-shaped. For evidence they bring the fact that, as the sun rises and sets, the part concealed by the earth shows a straight and not a curved edge, whereas if the earth were spherical the line of section would have to be circular. In this they leave out of account the great distance of the sun from the earth and the great size of the circumference, which, seen from a distance on these apparently small circles appears straight. Such an appearance ought not to make them doubt the circular shape of the earth. But they have another argument. They say that because it is at rest, the earth must necessarily have this shape. For there are many different ways in which the movement or rest of the earth has been conceived.

Here we see the cognisance of the fact that the curvature tends to be linear when see it is too large. Aristotle then goes on to discard the ideas by Anaximenes, Anaxogoras and Democritus who claim that flatness of the Earth is responsible for it being still. He argues, even a spherical Earth can remain at rest. The Earth being at rest and it being spherical are related. In Part 14 he takes this discussion further. The first argument uses the symmetry of weight distribution.

Its shape must necessarily be spherical. For every portion of earth has weight until it reaches the centre, and the jostling of parts greater and smaller would bring about not a waved surface, but rather compression and convergence of part and part until the centre is reached.

He further argues using reasoning of additional weight distribution how a spherical Earth can still be

If the Earth was generated, then, it must have been formed in this way, and so clearly its generation was spherical; and if it is ungenerated and has remained so always, its character must be that which the initial generation, if it had occurred, would have given it. But the spherical shape, necessitated by this argument, follows also from the fact that the motions of heavy bodies always make equal angles, and are not parallel. This would be the natural form of movement towards what is naturally spherical. Either then the earth is spherical or it is at least naturally spherical.

After this, he looks at evidence from lunar eclipses to reason that Earth is indeed spherical.
eclipse

The evidence of the senses further corroborates this. How else would eclipses of the moon show segments shaped as we see them? As it is, the shapes which the moon itself each month shows are of every kind straight, gibbous, and concave-but in eclipses the outline is always curved: and, since it is the interposition of the earth that makes the eclipse, the form of this line will be caused by the form of the earth’s surface, which is therefore spherical.

Finally Aristotle takes into account the fact that stars change their positions in the sky relative to the horizon when we move to North or South, indicating that we are indeed on a spherical surface. This will not happen on a flat surface.
stars

Again, our observations of the stars make it evident, not only that the earth is circular, but also that it is a circle of no great size. For quite a small change of position to south or north causes a manifest alteration of the horizon. There is much change, I mean, in the stars which are overhead, and the stars seen are different, as one moves northward or southward. Indeed there are some stars seen in Egypt and in the neighbourhood of Cyprus which are not seen in the northerly regions; and stars, which in the north are never beyond the range of observation, in those regions rise and set. All of which goes to show not only that the earth is circular in shape, but also that it is a sphere of no great size: for otherwise the effect of so slight a change of place would not be quickly apparent.

Another evidence which can be seen since antiquity is that the masts of the ships on ocean became visible first on the horizon, the ship appear later. This can be simply explained by assuming that the surface of the ocean is curved too.
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Thus we have seen the ancient evidence for a spherical Earth. It was well known and well established fact, both theoretically and empirically.
Images from:
All About The Telescope – P. Klushantsev
A Book About Stars and Planets – Y. Levitan
Physics for The Inquiring Mind – Eric Rogers.
 

On PhD

And then there’s a joke in which a young man told his mother he would become a Doctor of Philosophy and she said, “Wonderful! But what kind of disease is philosophy?

The Blank Slate, Steven Pinker

The Wolf-Children of Midnapore

Physics was one of the first sciences which helped develop the modern “scientific method”. One of the processes in the scientific method involves controlling of variables during an experiment. Performing an experiment in this manner one can possibly find the effect of the independent variable on a dependent variable. In this manner, we are supposed to find out if there is any causal link/correlation between the variables. This method was seen as a hallmark of true science and was widely adopted while discovering and developing new other disciplines.
Now in the case of psychology and behavioural sciences, we have a long-running debate regarding the effects of nature and nurture on human growth and development. By nature here it is meant our genetic make-up, while by nurture it is meant the environment (both physical and social) around us. For long people have tried to establish the link between nature/nurture and various aspects of human growth and development. This dichotomy has a deeper connection to the nature of knowledge and learning, which in turn in related to the two basic schools of philosophy: empiricism and rationalism. In the extreme forms, put very crudely, empiricism proposes that we can gain knowledge through our sense organs only, while rationalism proposes that we make sense of the world in our mind only. For example, in The Matrix the machines have developed a simulation which makes the human mind “experience” the world only in the mind. When Morpheus asks Neo

What is real? How do you define ‘real’? If you’re talking about what you can feel, what you can smell, what you can taste and see, then ‘real’ is simply electrical signals interpreted by your brain.

Here Morpheus is actually subscribing to the rationalist school as he denies that our sense organs are the primary source of our knowledge. In The Matrix the brain is simulated and it doesn’t know it is being simulated. How can we ever know? This is exemplified further by many Gedanken experiments which have been brought out by psychologists and philosophers. The Brain in a Vat is an example of such experiments.
On the other hand, the other extreme form of human development from empiricists would be considering humans a tabula rasaIn this perspective, the human brain is not born with any innate capabilities. And it is the experience with the physical world through the sense organs makes us understand the world. Thus, in this case, the environment is the factor on which our growth and development occur.
Now coming back to nature vs nurture debate, whether people believe in either depends strongly on the orientation and grounding people have regarding how the society works. We will see what is the basis both philosophical, epistemological and political when people subscribe to these viewpoints. First some thoughts on what exactly we mean by human growth and development in this context. We all see human babies grow from infants who are incapable of talking, understanding, even walking for that matter to being adults in a society who can talk, understand and do a variety of other things which infant versions of ours are not capable. How does this change occur, over let’s say a span of 15-20 years or so? Are we predestined by our genes to develop in a particular way, or does our immediate environment play a fundamental and crucial role in making this happen? What is the nature of learning and what is it dependent upon? Physical growth can be perhaps linked to the unfolding of the genetic predispositions that we have. For example, physical maturity occurs with age. Piaget has given us evidence on the basis of the so-called Piagetian tasks that thinking also matures with age and is a universal phenomenon across cultures.
But what happens to our thinking or our behaviours are they too natural and will occur even if we are not in contact with the society? People have thought over this question for a long time. We will discuss the evidence that people over the last 200 years or so have put up in support of each side, which is related to the title of the post.
In general, there are two groups who subscribe to the primacy of nurture in human development. The first group is of the people who are usually are influenced by Marxism and have a left orientation tend to favour nurture more than the nature aspect. According to them the social environment, including the socio-economic status of the family influence the way in which humans develop and learn. For this school of thought, the genetic composition (nature) of the individual has little or no effect on the way the individual develops or learns. This is in line with the central tenets of Marxism, in which capital plays a fundamental role in the way society works. The construct of cultural capital is a good way to understand how this group, in general, thinks about the effects of society and societal factors on human growth and development.
The other school which subscribes to the primacy of nurture in human learning and development is behaviourism. The behaviourists, very strongly influenced by logical positivists, and playing along with the zeitgeist gave credence in psychological studies to only things that could be observed. This was linked to the deep debates in the philosophy of science of the 1930s which was dominated by the logical positivists. The basic idea was that if anything is not observable directly by our sense experience like human thinking, it should not be considered scientific. This led to an entire programme which was very influential during the 30s-50s in which studying higher order thinking skills were banished from scientific enterprise. The definition of learning in case of behaviourists was seen in terms of behaviour. And according to them, the behaviour could be controlled by operant conditioning hence effectively we could control learning by providing required stimulus in the environment.
Bringing in the metaphor of a blank slate, people with this leaning would say all individuals are of equal potential, given a chance and environment anyone can perform anything. This was one of the basic assumptions of behaviourism. In Marxist sociological perspective, the metaphor of the blank slate allowed individuals to transcend the class that they were born in and to achieve their true potential irrespective of the social status of their parents. The quote below summarises this viewpoint very well:

Give me a dozen healthy infants, well-formed, and my own specified world to bring them up in and I’ll guarantee to take any one at random and train him to become any type of specialist I might select – doctor, lawyer, artist, merchant-chief and, yes, even beggar-man and thief, regardless of his talents, penchants, tendencies, abilities, vocations, and race of his ancestors. I am going beyond my facts and I admit it, but so have the advocates of the contrary and they have been doing it for many thousands of years.

From – Behaviorism by J. B. Watson, 1930, pp. 82.
Now let us look at the other group which takes the genetic makeup of ours as the most influential aspect for development and learning. In this perspective, your genes determine everything. There is no scope for anyone to do anything which the genes do not permit. Sometimes this is termed as genetic determinism. According to this view, the potential for learning and development is completely determined by genes. Unless one has a particular genotype, one by definition, is not capable of doing certain things. Now, of course, we do inherit our biological and physical structures from our parents. Physical characteristics like hair and eye colour, skin colour, size are inherited from our parents. So are tendencies for certain diseases like diabetes and others. Now the question that is interesting is this heritance limited to only physical characteristics or it can be used for determining other factors like intelligence, learning and development also?
In general, the people who are conservatives, leaning towards the right favour this point of view. This is because it provides a sort of legitimacy to the existing social order. The people who are in positions of power are there because they have better genes or are from a better stock. This also implies that nothing can be done to improve this situation as nature is unmutable. Of course, this position has racial, class gender, and caste overtones. Such an argument can be used to effectively defend and justify any existing social order. Sometimes, this entire range of ideas is put under the notion of Social Darwinism. Analogies from the natural world like artificial selection and breeding for producing better breeds (of plants and animals) are used to justify such a worldview. The movie GATTACA shows an example of a dystopian future is a good example of how a society where your genes are the only factors to determine your worth. In such a world, what matters is what your genes are, and not your skills.
Now apart from the philosophical, sociological and cultural aspects do we have any “scientific evidence” for deciding which factors are more influential. There have been many studies which claim a very strong evidence (mostly observational) regarding either worldviews. But none of the experiments or studies are seen to be conclusive. Critics on the other side point to experimental issues with data, samples, statistics, assumptions and personal beliefs and so on. Let us ask ourselves this question:

Can we design any critical experiments which will decide once and for all whether nature is important or nurture?

Ideally, the experimental design should be such that we should be able to control for nature and nurture. Now how would such an “ideal” experiment be designed? Let us look at each of the two variables. To control for nature we can take individuals from different genetic stocks and give them similar treatment. This way we will know from the differences in the outcomes/performance of the individuals and accordingly in their genes too. Now the question arises if we take adult individuals from different genetic stocks, they are already “contaminated” via the various nurture aspects of growing up. For example, they might have a different value system, a different language, different learning experiences, different social norms, different environments and so on. So ideally an “uncontaminated” sample should be with us.
How do we create an uncontaminated sample of human beings? Who are not touched by any aspect of nurture or environment? Ideally, we take don’t allow nurture to touch the newborn infants in any manner. That is to take them away from their mothers right after they were born. Oh! What a horror!! But such a thing would never be done in practice now. Though in the ancient times there were many who actually performed similar “experiments“. There are serious moral and ethical issues involved. Now strict research guidelines are in place whenever human subjects are involved in research studies. This came to force when evidence emerged post-World-War II which involved experimenting on human subjects by treating them like animals. That is basically not valuing human life and dignity. Hence I had put “ideal” in quotes.
In Rudyard Kipling’s The Jungle Book the protagonist Mowgli, is raised by the wolves. Although fictional, this story presents us with an interesting case study. Mowgli, who has been raised by the wolves, is not human in the sense of how we identify with the society. He identifies himself as a wolf and behaves like one. But then this is fictional story and a Mowgli is a fictional character. Now if we could find such an individual like Mowgli, we could perhaps test many of the basic questions regarding aspects of nature and nurture. One such opportunity came to us in an episode which is the title of this post: The Wolf-Children of Midnapore.
Now it so happened that in 1920s a rector  Joseph Amrito Lal Singh in an orphanage in the town of Midnapore in Bengal, India reportedly found two girls in a wolf den. They were named Amala and Kamala. The discovery of these two girls was seen as a major event. The rector apparently maintained details notes about their discover and behavior in his diary. So much so, it was published into a book Wolf-Children and Feral Man J.A.L. Singh and Robert M. Zingg published in 1942. The discovery was also reported in a reputed journal as Scientific American (Vol. 164, No. 3 (MARCH · 1941), pp. 135-137).
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So what did the rector observe in these two children? Can it resolve any fundamental questions regarding the nature-nurture debate? The book and the entries in the diary of Rev. Singh make many such attempts. However, it so happened that people raised serious doubts about the authenticity of the story, and further analysis has shown that it was a hoax. Recently, there was a case in which a girl was discovered living with monkeys. Again, girl showed some feral characteristics, but according to some reports nothing conclusive could be said.
So our basic question regarding nature/nurture remains unanswered. Perhaps due to moral and ethical concerns we may never be able to answer question on “experiments” such as these. But there have been other ways, surveys, studies and experiments which do indicate the complex ways in which nature and nurture do interact to produce the social human animal. But what cases like these show is that there is so much that is still to be discovered in the respect of nature/nurture debate. Perhaps we will be able to resolve these issues at some point.
http://www.midnapore.in/wolf-children-of-midnapore/wolf-children-of-midnapore14.html

The Villain

Can’t but help post this little gem from an eleventh-century Sanskrit author by the name of Kshemendra. This is the first chapter of his book Desopadesa which is a satirical work on different types of base people in the society. One can’t stop from making the comparison of people around us, particularly those in power with what he describes.

The Villain

Salutations to the villain. He is like a mortar: full of chaff as well as grain, and always fit for crushing both. Friend and foe are the same to him, as are respect and derision, and he is practised at bypassing rules. Thus is he ordained for salvation/ but he is also vile, like a dog: greedy for crumbs, fierce in quarrels and always dirty. His tongue pollutes the worthy as the dog’s does the bowl. In tardiness, malevolence and harming good works out of ill will, he is like the planet Saturn. Strangely, he is also that planet’s opposite: a thunderbolt that strikes mankind. (5-8)
Though a fool devoid of sacred learning, the villain claims to be a scholar because of his past good deeds. In extolling his own merits he is like Shesha, the thousand-headed serpent, and in running down others, like Brihaspati, the guru of the gods.
His throat is so afflicted with jealousy that his tongue cannot utter words of praise for the good, even if it is pulled out with a pair of tongs; though in slandering them, he has eyes and mouths on every side. His ears, too, are everywhere, and he hears all as he bides his time. (9-11)
The villain is like the world: illusory by nature; afflicted by passion, hatred and craziness; deluding even great minds. Whom has he not corrupted? Like a person’s pubic parts, he is, in fact, a source of shame, addiction and infatuation, and an instigator of desire. (12-13)
Ignoring his own and another’s food, the wretch always sits close to his patron, whispering slander into his ear as if it were the cosmic science. Indeed, he talks of everyone’s faults. But who talks of his? For who will ever discuss the blemishes in a dirty garment? As if in sport, the trickster even creates pictures in the sky: But he is still considered base, for among the tall he remains puny: (14-16)

With a villain, influential,
mad for money, base and cruel,
holding high office,
O people, alas, where will you go? (17)

Yet, a villainous fool is preferable to a clever villain, just as a toothless snake is to a deadly serpent, black and winged. Pollution follows the villain as it did the ogre Khara. Both are spoilers of human habitation; arrogant and hostile to the learned; devourers of mankind. Should a villain tum, by some stroke of luck, into a sincere and good person, it would be like an ape in the forest turning to prayer with its arms upraised. (18-20)
To say that a villain will praise merit is questionable, that he will love, unreasonable, and that he will give something, quite meaningless. But to say that he will kill cannot be an untruth. Influencing the master by whispering slanders in his ears night and day, I believe he spreads his control everywhere. What is the worth of anything, in the course of getting which the dust from his chamber door will adorn one’s head? It can only be a defect, never a merit. Arrogant with a bit of money, given to grand talk, the villain is a strange invention of the Creator. With eyebrows raised, he maligns, in public gatherings, the reputations of good men, which are as radiant as the expanse of Mount Kailasa.
(21-24)
from Desopadesa by Kshemendra