Galileo’s Experiments on Accelerated Motion

A short account of Galileo’s description of his own experiment on accelerated motion — a short account of it, the apparatus he used and the results he got.

The first argument that Salviati proves is that in accelerated motion the change in velocity is in proportion to the time (𝑣 ∝ 𝑡) since the motion began, and not in proportion to the distance covered (𝑣 ∝ 𝑠) as is believed by Sargedo.

“But for one and the same body to fall eight feet and four feet in the same time is possible only in the case of instantaneous (discontinuous) motion; but observation shows us that the motion of a falling body occupies time, and less of it in covering a distance of four feet than of eight feet; therefore it is not true that its velocity increases in proportion to the space. (Salviati)

Also, he proves that the increase in proportion is not of simple doubling but larger. They agree upon a definition of uniformly accelerated motion,

“A motion is said to be equally or uniformly accelerated when, starting from rest, its momentum receives equal increments in equal times. (Sargedo)

To this definition Salviati adds an assumption about inclined planes, this assumption is that for a given body, the increase in speed while moving down the planes of difference inclinations is equal to the height of the plane. This also includes the case if the body is dropped vertically down, it will still gain the same speed at end of the fall as it would gain from rolling on the incline This assumption makes the final speed independent on the profile of the incline. For example, in the figure below, the body falling along𝐶 → 𝐵, 𝐶 → 𝐷 and 𝐶 → 𝐴 will attain the same final speed.

This result is also proved via a thought experiment (though it might be feasible to do this experiment) for a pendulum. The pendulum rises to the height it was released from and not more.

After stating this theorem, Galileo then suggests the experimental verification of the theorem. of The actual apparatus that Galileo uses is an wooden inclined slope of following dimensions: length 12 cubits (≈ 5.5 m, 1 cubit ≈ 45.7 cm), width half-cubit and three-finger breadths thick . In this plank of wood, he creates a very smooth groove which is about a finger thick. (What was the thickness of Galileo’s fingers?) The incline of this plank are changed by lifting one end. A bronze ball is rolled in this groove and time taken for descent is noted.

“We repeated this experiment more than once in order to measure the time with an accuracy such that the deviation between two observations never exceeded one- tenth of a pulse-beat.

Then Galileo performed variations in the experiment by letting the ball go different lengths (not full) of the incline and “found that the spaces traversed were to each other as the squares of the times, and this was true for all inclinations of the plane”. Each variation was repeated hundreds of times so as to rule out any errors. Also, the fact that for different inclines the times of descent were in noted and were in agreement with the predictions.

Since there were no second resolution clocks to measure time, Galileo devised a method to measure time using water. This was not new, water clocks were used earlier also.

The basic idea was to the measure the amount of water that was collected from the start of the motion to its end. The water thus collected was weighed on a good balance.This weight of water was used as a measure of the time. A sort of calibration without actually measuring the quantity itself: “the differences and ratios of these weights gave us the differences and ratios of the times”

Galileo used a long incline, so that he could measure the time of descent with device he had. If a shorted incline was used, it would have been difficult to measure the shorter interval of time with the resolution he had. Measuring the free fall directly was next to impossible with the technology he had. Thus the extrapolation to the free fall was made continuing the pattern that was observed for the “diluted” gravity.

“You present these recondite matters with too much evidence and ease; this great facility makes them less appreciated than they would be had they been presented in a more abstruse manner. For, in my opinion, people esteem more lightly that knowledge which they acquire with so little labor than that acquired through long and obscure discussion. (Sargedo)

 

Reference

Dialogues Concerning Two New Sciences

Experiments, Data and Analysis

There are many sad stories of students, burning to carry out an experimental project, who end up with a completely unanalysable mishmash of data. They wanted to get on with it and thought that they could leave thoughts of analysis until after the experiment. They were wrong. Statistical analysis and experimental design must be considered together…

Using statistics is no insurance against producing rubbish. Badly used, misapplied statistics simply allow one to produce quantitative rubbish rather than qualitative rubbish.

–  Colin Robson (Experiment, Design and Statistics in Psychology)

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).

Screen Shot 2018-09-20 at 8.16.26 AM

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

Does Tulsi has environmental benefits too?

Recently there was a news item in Times of India which had the same heading as that of this particular post. The news claimed

(Around two decades back Dada Dham, a socio-spiritual organization brought together a team of botanists, ayurvedic scholars and environmental enthusiasts to study the environmental benefits of tulsi.)

NAGPUR: Ayurvedic medicinal values of Tulsi are well known. Our ancient scriptures have enumerated the medicinal benefits of tulsi. Its extracts are used widely for curing common ailments like common cold, headache, stomach disorder etc.

But the environmental benefits have been comparatively unknown. Around two decades back Dada Dham, a socio-spiritual organization brought together a team of botanists, ayurvedic scholars and environmental enthusiasts to study the environmental benefits of tulsi.

Now the next claim from an “eminent botanist” that the report does is startling indeed.

“Tulsi gives out oxygen for 20 hours and ozone for four hours a day along with the formation of nascent oxygen which absorbs harmful gases like carbon monoxide, carbon dioxide and sulphur dioxide from the environment,” said Shyamkant Padoley, an eminent botanist.
How would the tulsi plant (Ocimum tenuiflorum) do this? Is it anatomically so different that it is capable to do this? How does the plant regulate this 20 and 4 hour cycle?  I would really like to know. How is that no other plants have this cycle? How did they detect presence of ozone, what detectors they used? What mechanisms in presently known cycle of photosynthesis account for this cycle? And if this is part of the standard photosynthesis process, then all plants should have it. This seems fishy, and a most preliminary search did not yield any positive result. All of them talk about production of oxygen and not ozone, as reported by Padoley. And if this is indeed true, it might lead to change in our conception of the photosynthetic cycle.
And if the ozone report is to be believed at all then this is what ozone does to you quote from Wikipedia article on ozone:
Ozone is a powerful oxidant (far more so than dioxygen) and has many industrial and consumer applications related to oxidation. This same high oxidizing potential, however, causes ozone to damage mucus and respiratory tissues in animals, and also tissues in plants, above concentrations of about 100 parts per billion. This makes ozone a potent respiratory hazard and pollutant near ground level.
There is evidence of significant reduction in agricultural yields because of increased ground-level ozone and pollution which interferes with photosynthesis and stunts overall growth of some plant species. The United States Environmental Protection Agency is proposing a secondary regulation to reduce crop damage, in addition to the primary regulation designed for the protection of human health.
There is a great deal of evidence to show that ground level ozone can harm lung function and irritate the respiratory system.Exposure to ozone and the pollutants that produce it is linked to premature death, asthma, bronchitis, heart attack, and other cardiopulmonary problems.
Ozone is air pollutant, green house gas.
To summarize this is that ozone is NOT GOOD for us at ground level! It may do us good in upper atmosphere to block UV Rays, but down here on ground it is bad. And if this claim of ozone production by Tulsi is true why is the campaign of “Tulsi lagao pradushan hatoa (Plant tulsi, remove pollution)” which follows in the article is being implemented?

Padoley, member of technical committee, ministry of environment and forest, NewDelhi, and forest tech committee, also read a paper at the International Conference on Occupational Respiratory Diseases at Kyoto in 1997 where cyclo oxygenate, an enzyme only found in tulsi was labelled for the first time. This enzyme regulates the entire mechanism of oxygen evolution. (emphasis added)

This again I am unable to understand. It says this enzyme is “only found in Tulsi”, and it also “regulates entire mechanism of oxygen evolution”. One can agree that a particular enzyme is found in a particular plant, but if this enzyme controls “entire mechanism of oxygen evolution”, how do other plants regulate their mechanisms of oxygen evolution.

Dada Dham initiated a campaign ‘Tulsi Lagao Pradushan Hatao’ in 1987 under the guidance of Narendra Dada, the institution’s head. It was under this campaign that the above mentioned panel of experts was formed. After finding out the environmental benefits of the plant, Dada Dham organized a number of programmes like street plays, nukkad sabhas and lectures to propagate the use of the plant.

Dr Dattatraya Saraf, an ayurvedic doctor and expert said, “The plant enriches the environment with oxygen almost 24X7 and also absorbs other pollutants.” He further added that if the size of the plant can be increased, the environmental benefits can be increased.

This statement that “plant enriches the environment with oxygen almost 24X7” is in contradiction to statement by above Padoley regarding 20 and 4 hour cycles. Which one is to be believed? And mind you this is just appearing a few lines later, this is either very poor editing and reporting, or hogwash to the public.

“That is why we want to urge scientists and concerned authorities to make research on the issue of increasing the height of tulsi plant. If big trees can be converted to bonsai plants then big tulsi trees can be possible too,” said Kishor Verma, PRO of Dada Dham.

This is another statement that I would like to contest. Did they compare the rate of oxygen production vis-a-vis to other plants. That is to say simply did they have any control sample? And does making “tulsi tree” make any sense (can one really do it is another question), will it really increase oxygen making capabilities, is it a linear relationship between these two variables? The water is completely muddy in this !

He also citied the research and work by other organization in support of tulsi’s environmental benefits.

“The forest department of Uttar Pradesh, with the help of an organization called Organic India Limited, Lucknow planted lakhs of tulsi saplings around Taj Mahal to protect its surface from industrial emissions. This step has yielded positive results,” Verma said.

“We are just asking the administration to take notice of these extra ordinary benefits of tulsi and take steps for utilizing them. Even simple steps like planting tulsi plants on road dividers, parks etc can bring a difference,” said Verma.

The reporter and also the editor make no effort to correct these glaring inconsistencies in the report itself, forget about doing nay research on the topic, or verifying the claims made by these people. Maybe this was like the paid news that is talked about a lot these days.

What I find here i that the agenda of what is to be done was already set, the conclusions were already drawn, by our ancestors, written in black and white in ancient texts. The point was only to justify what they were doing, and trying to provide a “scientific basis” of what they already believed to be true (for whatever reasons, mostly religious, and presence of a religious organization in this sort of confirms this).

A good example of  pseudo-science and bad science reporting.