The theory of relativity includes two theories (that of the special relativity and that of the general relativity) formulated by Einstein at the beginning of the twentieth century, which sought to solve the incompatibility existing between the Newtonian mechanics and the electromagnetism.
The first theory, published in 1905, deals with the physics of the movement of the bodies in the absence of gravitational forces, in which the Maxwell equations of electromagnetism were made compatible with a reformulation of the laws of the movement. The second, of 1915, is a theory of gravity that replaces Newtonian gravity but coincides numerically with it in weak gravitational fields.
It was not until March 7, 2010, that the original Einstein manuscripts were publicly shown by the Israeli Academy of Sciences. The manuscript has 46 pages of hand-drawn mathematical texts and formulas, had been offered by Einstein to the Hebrew University of Jerusalem in 1925, on the occasion of its inauguration in Palestine, then under British Mandate.
1. Darwin and Evolution
- 1 1. Darwin and Evolution
- 2 Newton and Inertia
- 3 Pythagoras and the numbers
Being a lion or a cat or a rose carries something special, something that no other animal or plant shares with it. Each one of them is a unique species of vegetable or animal. Only lions can bear lion cubs, only cats can have gambling, and only pink seeds — and not carnations — can come out of roses.
Even so, it is possible that two different species show similarities. Lions look a lot like tigers, and jackals to coyotes, even though lions only breed lions and not tigers, and the jackals just stop jackals and not coyotes.
And it is that the whole realm of life can be arranged conveniently in groups of similar creatures. When scientists first became aware of this, many thought it could not be pure coincidence. Two similar species were they because some members of one of them had become part of the other? Wouldn’t it be that they looked alike because they were both intimately related?
Some Greek philosophers had suggested the possibility of a relationship between the species, but the idea seemed by then too far-fetched and had no echo. It seemed unlikely that some lions would have turned into tigers, or vice versa, or that some feline creature would have spawned both tigers and Lions. No one had ever seen such a thing; Had it happened, it had to have been a very slow process.
Most people believed, at the beginning of modern times, that the earth was only about six thousand years old: an absolutely insufficient time for species to change nature. The idea was rejected by absurd.
But was it true that the earth was only six thousand years old? The scientists who studied at the beginning of the eighteenth century the structure of the
Rocky layers of the Earth’s crust began to suspect that these strata could only have been formed after very long periods of time. and towards 1760 the French naturalist Georges de Buffon dared suggest that the earth could have up to seventy-five thousand years.
A few years later, in 1785, Scottish physician James Hutton took things a little farther. Hutton, who had adopted his fondness for minerals as the central occupation of his life, published a book titled Earth Theory, where he gathered abundant data and solid arguments that showed that our planet could actually have many millions of years of age. Hutton asserted without ambages that he saw no signs of any origin.
The door opens
For the first time it seemed possible to talk about the evolution of life. If the earth was millions of years old, there had been plenty of time for animals and plants to have slowly transformed into new species, so slowly that man, in the few thousand years of civilized existence, could not have noticed that evolution.
But why would they change the species? And why in one direction and not in another? The first person who tried to answer this question was the French naturalist Jean Baptiste de Lamarck.
In 1809 he presented Lamarck his theory of evolution in a book titled Zoological Philosophy. The theory suggested that the creatures changed because they tried to change, without necessarily know what they were doing.
According to Lamarck, an antelope that feeds on tree leaves would stretch its neck upward with all its forces to reach the maximum amount of grass; And along with his neck he would also stretch his tongue and legs. This stretch, maintained throughout life, would cause the legs, neck and tongue to lengthen slightly.
The offspring born of this antelope would inherit this elongation of the body proportions. The offspring would lengthen the body even further by an identical stretching process, so that, little by little, over thousands of years, the process would come to a point where the lineage of the antelopes convert into a new species: the giraffe.
Lamarck’s theory was based on the concept of inheritance of acquired characters: the changes that were operated on the body of a creature throughout its life passed to the offspring. The downside is that the idea lacked entirely empirical support. And when it was investigated it became more and more clear that it could not be true. Lamarck’s doctrine had to be abandoned.
In 1831, a young English naturalist named Charles Darwin was enlisted on a chartered boat to explore the world. Shortly before sailing he had read a book of geology written by another English minion, Charles Lyell, where he commented and explained Hutton’s theories about the age of the Earth. Darwin was impressed.
The journey through remote shores and the scales on islands that were little less than unexplored gave Darwin the opportunity to study species still unknown to Europeans. Special interest aroused in him the animal life of the Galapagos Islands, located in the Pacific, about a thousand kilometers from the coast of Ecuador.
Darwin observed fourteen different species of finches on these remote islands. All of them differed slightly from the others and also from the finches that lived on the South American coast. The beak of some of the finches was well designed to eat small seeds; that of others, to split large seeds; A third species was armed with an ideal beak to eat insects; And so on.
Darwin intuiteded that all these finches had their origin in a common ancestor. What made them change? The idea was the following: it could be that some of them had been born with slight modifications in the beak and that they had then transmitted these innate characteristics to the offspring. Darwin, however, was still harboring his doubts, because those accidental changes would be enough to explain the evolution of different species?
In 1838 he found a possible solution in the book titled An Essay on the principle of population, published in 1798 by the English cleric Thomas R. Malthus. Malthus maintained that the human population was growing ever faster than its food resources. Therefore, the number of inhabitants would be reduced ultimately by hunger, if not by diseases or wars.
Darwin was impressed by the arguments of Malthus, because they made him see the powerful force that nature could exert, not only on the human population, but on the population of any species.
Many creatures multiply with great prodigality, but the offspring survive only a small proportion. It occurred to Darwin that, speaking in general terms, only those individuals who were more efficient in one aspect or another were going out. Among the finches, to put a case, only those who were born with slightly more robust beaks would survive, being more able to crush hard seeds. And those others who were able to digest from time to time an insect would have even greater odds of surviving.
Generation after generation, finches that were slightly more efficient in any respect would survive at the expense of the less effective. And since that efficiency could occur in very diverse terrains, in the end there would be a whole series of very different species, each one specializing in a different function.
Darwin believed it justified to claim that this process of natural selection was worth not only to finches, but to all creatures. Natural selection determined which individuals should survive, at the cost of starving those who enjoyed no superiority trait.
Darwin worked on his theory of natural selection for years. Finally he poured in 1859 his ideas in a book titled: On the origin of the species by means of the natural selection, or the preservation of the favored races in the fight for the life.
The ideas of Darwin raised at the beginning acrimonious controversies; But the amount of evidence accumulated over the years has confirmed the central core of its theories: the slow change of species through natural selection.
The idea of evolution, originally envisioned by Greek philosophers and who finally left Charles Darwin seated, revolutionized biological thought in its entirety. It was undoubtedly the most important idea in the history of modern biology.
Newton and Inertia
Aristotle observed that down here, on earth, everything changes or disintegrates: Men age and die, buildings deteriorate and collapse, the sea curls and then calms, the winds carry and bring the clouds, the fire turns on and then goes out , and the Earth itself trembles with earthquakes. In the skies, on the contrary, only serenity and immutability seemed to reign. The sun went out and set on time and its light never rose or lowered in brightness. The moon shelled its phases in regular order, and the stars shone without fainting.
Aristotle concluded that the two parts of the universe functioned according to rules or “natural laws” of different species. There was a natural law for the objects of the Earth and another for celestial objects.
Some forty years after the death of Galileo (who had defied Aristotle with regard to the speed in the fall of the Bodies), the English scientist Isaac Newton studied the idea that the resistance of the air influenced the objects in movement and achieved Discover other ways to interfere with it.
It established the laws of classical mechanics, both in static and dynamic, laws that allowed to direct a rocket to the moon.
I create a new mathematical branch or differential calculus, in order to study and deepen their theoretical studies on natural phenomena.
He developed the theory of gravity among the bodies of the universe.
He proposed a corpuscular theory to explain the optical phenomena.
You are saying that Newton proved that Aristotle was mistaken to think that there were two sets of natural laws, one for heaven and another for Earth.
The three laws of the movement explained just as well the fall of an apple or the bounce of a ball that the trajectory of the moon. Newton showed so that the heavens and the earth were part of the same universe.
Pythagoras and the numbers
Very close to the time of such, about 2500 years ago there was another Greek sage called Pythagoras, who lived in Crotona, in the south of Italy. He had gotten strings of musical instruments and was determined to make some experiences and relate mathematical numbers to the notes that those strings generated.
He did many experiments and it was he, the first man to study, not the music, but the game of lengths that produced the music. Why were these proportions of simple numbers — 2 to 1, 3 to 2, 4 to 3 — the ones that originated particularly pleasing sounds? , he had found the musical numbers, which both marveled at his ears.
And if the numbers were so important, it was worth studying them in themselves. You had to start thinking, for example, in number 2 to dry, not in two men or two apples. Number 2 was divisible by 2; It was an even number. Number 3 could not be divided exactly by 2; It was an odd number. What properties shared all the even numbers? What about the odd ones? It could begin with the fact that the sum of two odd or even two numbers is always an even number, and that of a pair and an odd is always odd. He continued to investigate and obtained the numbers square, triangular, etc..
Later it followed with geometry and showed the property between the sides of a triangle rectangle, expressing its famous conclusion, that almost all of us still remember the secondary school: “The square of the hypotenuse of a triangle rectangle, is equal to the sum Of the square of their Hicks ”
We can say that the teachings of Pythagoras, and especially his great success in finding a deductive proof of the famous theorem, were a source of inspiration for the Greeks, who continued working on this line. In the 300 years following erected a complex structure of mathematical tests that relate mainly to lines and forms. This system is called ‘ geometry ‘.
In the thousands of years that have elapsed since the Greeks have made much progress in science. But, however much the modern man has achieved in the field of mathematics and penetrated in his mysteries, everything rests on two pillars: first, the study of the properties of the numbers, and second, the use of the method of deduction. The first was born with Pythagoras and the second was reported by him. What Pythagoras had torn from his strings were not only musical notes: It was also the vast world of mathematics.
Nicolás Copernicus and the heliocentric theory
The heliocentric theory holds that the Earth and the other planets revolve around the Sun (star of the Solar system). The heliocentrism, was proposed in ancient times by the Greek Aristarchus of Samos, who was based on simple measures of the distance between the Earth and the sun, determining a much greater size for the sun than for the Earth. For this reason, Aristarchus proposed that it was the earth that revolved around the sun and not vice versa, as was the geocentric theory of Ptolemy and Hipparchus, commonly accepted at that time and in the following centuries, according to the prevailing anthropocentric vision.
More than a millennium later, in the sixteenth century, the theory would be formulated again, this time by Nicolás Copernicus, one of the most influential astronomers of history, with the publication in 1543 of the book of Revolutionibus Orbium Coelestium. The fundamental difference between Aristarchus’s proposal in antiquity and Copernicus ‘ theory is that the latter employs mathematical calculations to support his hypothesis. Precisely because of this, his ideas marked the beginning of what is known as the Scientific Revolution. Not only a very important change in astronomy, but in the sciences in general and particularly in the worldview of civilization. From the publication of his book and the Refutation of the geocentric system defended by Greek astronomy, civilization breaks with the idealization of the indisputable knowledge of antiquity and launches with greater impetus in search of knowledge.
Einstein and unified field theory
Einstein dedicated his last years to the search for one of the most important theories of physics, the so-called unified field theory. This search, after its general theory of relativity, consisted of a series of attempts to generalise its theory of gravitation to unify and summarize the fundamental laws of physics, specifically gravitation and Electromagnetism. In the year 1950, he exhibited his unified field theory in an article titled “On the Generalized Theory of gravitation” (on the Generalized theory of gravitation) in the famous Scientific American magazine.
Although Albert Einstein was world famous for his work in theoretical physics, Paulitinamente was isolated in his research, and his attempts were unsuccessful. Pursuing the unification of the fundamental forces, Albert ignored some important developments in physics, being notably visible on the issue of strong nuclear and weak nuclear forces, which were not understood well but after fifteen years of the Einstein’s death (around the year 1970) through numerous experiments in high-energy physics. The attempts proposed by string theory or M theory show that it still endures its momentum of attaining to demonstrate the great theory of the unification of the laws of physics.
Hippocrates and medicine
How wonderful is the miracle of life and how amazing are the living things! The smallest plant, the tiniest animal seems more complex and interesting than the larger mass of inert matter we can imagine.
Because, at the end of the day, inert matter doesn’t seem to do anything most of the time. Or if you do something, you act in a mechanical and uninteresting way. Let’s think of a stone that lies on the road. If nothing disturbs her, she will remain there forever and ever. If we kick him, he’ll move and he’ll stop again. We give it stronger and it will move away a little more. If we throw it in the air, it will describe a curve in a certain way and fall. And if we hit it with a hammer, it’ll break.
With some experience it is possible to predict exactly what will happen to the stone in any circumstance. One can describe their avatars in terms of cause and effect. If such a thing is done with the stone (cause), it will occur to you such another (effect). The belief that equal causes work more or less the same effects on all occasions leads to the vision of the universe we call “mechanism”
Democritus and the ÁtomosDemócrito
were born around the year 470 BC in the Greek city of Deraa. He always had a risueña attitude, and pleasant, his fellow citizens called them “the philosopher Ruiseño” and may take that attitude of his by symptom of madness, because the legend says they had him for lunatic and they came to collect the help of doctors to cure him .
Democritus seemed to house, of course, very pilgrim ideas. He was concerned, for example, how far a drop of water could be divided. One could go getting smaller drops to almost lose sight of them. But was there any limit? Did it ever come to a point where it was impossible to continue dividing?
Democritus announced his conviction that any substance could be divided up to a limit and no more. The smallest piece or particle of any kind of substance was indivisible, and to that minimum particle it called atoms, which in Greek means “indivisible”. According to Democritus, the universe consisted of these tiny and indivisible particles. In the universe there was nothing else but particles and empty space between them.
But it was at the end of 1700 when the chemist Joseph Louis Proust, chemist French, made very careful measurements of the formation of chemical compounds, like for example the carbonate of copper and verified, for example, that always that the copper, the oxygen and the carbon They formed copper carbonate, were combined in the same weight ratios: five units of copper per four of oxygen per one of carbon. In other words, if Proust used five ounces of copper to form the compound, he had to use four of oxygen and one carbon.
Shortly thereafter, another great English chemist named Dalton, thought: How strange!, “why should it be so?” and analyzed the possibility of indivisible particles. Wouldn’t it be that the oxygen particle always weighs four times as much as the carbon, and copper is five times more than this? By forming copper carbonate by combination of a copper particle, another of oxygen and another of carbon, the proportion of weights would then be 5:4:1.
Dalton announced his revolutionary theory of indivisible particles in the year 1803, but now in a somewhat different way. It was no longer a matter of actually believe or not. Behind him was a century of chemical experimentation, and in this way he could confirm that first and innocent idea that 2000 years before Democritus had proposed to the Greek world.
Faraday and the practical application of magnetic fields
The scientists of the early eighteenth century thought that the whole universe was working on the basis of these forces of contact: it was what is called a mechanistic vision of the universe.
Could there be forces without contact? No doubt: one of them was the gravitational force explained by Newton himself. The Earth pulled the moon and kept it in its orbit, but it did not touch it at all. Between the two bodies there was absolutely nothing, not even air; But still, both were linked by the great gravitational force.
Another kind of non-contact force can be observed if we place a vertical iron bar perfectly in equilibrium. All we need is a little magnet. We approach it to the top point of the bar and it leans towards the magnet and falls. The magnet does not need to touch the bar at all, nor is the air the cause of the phenomenon, because exactly the same thing happens in the void.
The English scientist Michael Faraday addressed in 1831 the problem of this mysterious force. He placed two magnets on a wooden table, with the North pole of one facing the South pole of the other. The magnets were close enough to attract, but not so much as to come together; The attraction at that distance was not enough to overcome the friction with the table. Faraday knew, however, that the force was there, because if he dropped iron filings between the two magnets, those were moving toward the poles and stuck to them. How to explain this invisible and magical phenomenon?
To experiment he used a white paper on the magnets and light iron filings, and he could observe that the same ones were moving on paper and were arranged following lines very similar in forms of arcs, to which it called magnetic lines, which in turn were generated by a Special power, called magnetic field.
Until then, the electric current could only be obtained with batteries, which are closed containers in which certain chemicals react. The electricity generated with batteries was quite expensive. Faraday’s new discovery allowed it to be generated with a steam engine that moved certain objects through magnetic force lines. The electricity obtained with these steam generators was very cheap and could be produced in large quantities. It should be said, then, that it was the magnetic lines of force that electrified the world in the twentieth century.
Tales of Miletus and his idea of science
The Greek thinker such in the year 600 BC wondered the following: What is the universe composed of?, and gave an answer, “All things are water.” Of course the idea was incorrect, but it is still one of the most important statements in the history of science, because without it — or another equivalent — there would be not even what we now understand as “science”.
It is not surprising that he has given this answer, for such was born and raised in a world surrounded by seas and oceans.
The continent, the firm land, had, according to such, the form of a disc of some thousands of miles in diameter, floating in the midst of an infinite ocean. Nor did he know that the continent itself was furrowed by the waters. There were rivers that crossed it, lakes scattered here and there and springs that arose from its bowels. The water dried up and disappeared in the air, to become then again in water and to fall in form of rain. There was water up, down and everywhere.
At that time the important thing was to build temples and altars, invent prayers and sacrifice rituals, fabricate idols and make magic. And the downside is that nothing could disqualify this system. Because let us suppose that, despite all the ritual, the drought was coming or the plague was unleashed. The only thing that meant that was that the healers had incurred error or omitted some rite; What they had to do was try again, sacrifice more cattle and pray with more fruition.
Instead, such his disciples posed a hypothesis (which was correct), they said that the universe worked according to natural laws that did not vary, and then it was worth studying the universe, observing how the stars move and how the Clouds, how the rain falls and how plants grow, and also in the assurance that these observations would always be valid and that they would not be unreasonably altered by the will of any god.
And then it would be possible to establish a series of elementary laws that describiesen the general nature of the observations. The first hypothesis of such led to a second: human reason is able to clarify the nature of the laws that govern the universe.
This thought so elementary in our life today was the great idea of such, to begin to study, and explain the natural phenomena through our reason, observing and experimenting.