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two general facts which at the outset speak very much in favour of the validity of the principle of relativity

The principle of relativity must therefore apply with great accuracy in the domain of mechanics

And that is, certain genes can evolve progressively over a long period of time, because they don't encode vital functions, or they may even be sequences between genes that don't encode phenotype at all. Imagine, for example, we have a situation were here we have a gene which encodes a vital function, like the eye, here's another gene that encodes another function, oh I don't know, a leg. And here we have intergenic sequences. After all, as you have learned by now, more than 96% of the DNA in our genome, doesn't encode proteins, and probably isn't even responsible for regulating genes. So these sequences, right in here, can mutate freely during the course of evolution, without having a deleterious effect on the phenotype of the organism. There's no evolutionary pressure to constrain the evolution of these genes

And many of these neutral mutations, which have no effect on organismic fitness, but are simply evolutionary neutral, are sometimes called polymorphisms. The term polymorphism, -morph is once again morphology, derives from the fact that species tend to be polymorphic, we don't all have blond hair, we don't all have brown eyes.

If you look at two chimpanzees living on opposite sides of the same hill in West Africa, they are genetically far more distantly related to one another, than any one of us, by a factor of 10 to 15. Two chimpanzees, they look exactly the same, they have the same peculiar habits, but they're genetically far more distantly-related than we are to one-another, than I am to any one of you, or than any one of you is to one another. And what does that mean? It means that, roughly speaking, the species of chimpanzees is, at least, 10 or 15 times older than our species are. We're a young species, chimpanzees probably first speciated three or four million years ago, if the paleontological record is, is accurate. Paleontology is the study of old, dusty bones, so you can begin to imagine when chimpanzee bones become recognizable in the earth.

And what you see already, in such small populations, is that for example, this male here has two girls, and right away, to the extent he had an interesting Y chromosome, that Y chromosome was lost from the gene pool. This girl, here, had an interesting mitochondrial DNA, but right away that's lost, because she has, she has just two boys. And what you see, in very rapid order, in small populations, there's a homogenization of the genetic compliment, just because the alleles are lost within what's called, genetic drif

And if you ask that question, the answer is that we all had a common ancestress who lived about 150,000 years ago. All of us trace our mitochondrial DNA to her. Does that mean that there was only one woman alive there, she's called, Mitochondrial-Eve, again, we don't know her name. Does that mean there was only one woman alive, well it doesn't mean that at all because of what I just told you, in small populations the proto-human population.

How much are all of our mitochondrial DNA are related to one another, how distantly related are they to one another, given the rate of evolution of mitochondrial DNA sequences?

So where do we all come from, all of us human beings? How closely related are we to one another? Here's, here's a measurement of the distances between different mitochondrial DNA's from different branches of humanity. And what you see is something really quite extraordinary and stunning. Here, you'll see that the people, the non-African lineages here and here, are actually relatively closely related to one another.

And by the way, all the genes that are present here, the alleles that are present here, can also be found in Africa, but in relatively small proportions in Africa

So, what happens there, that's a testimonial to the tragic fate of the Indians, where the conquistadors from Spain came in, killed all the men, and took all the women, to be their brides. How else can you explain the fact that there's no Indian Y chromosomes, there's all, there is instead only European Y chromosomes.

When you do genetic counseling of family these days, one of the strictures is, that you never tell the family if the children have genetic polymorphisms that don't match that of the person whom they think is their father. They don't look like their, the person whom they regard as father, but that's always assumed to be a role of the genetic dice.

Here's a fun story I like to tell each year, and it's about the Cohen and Y chromosome, and you'll see what an amusing story this is, just from genetics. Now the name Cohen, in Hebrew means, a high priest, and you've heard people named Cohen, it's not such an uncommon name among the Jews. And it says, in the Bible, in Genesis and Exodus, that all the high priests in the Bible are the descendants of Aaron, the brother of Moses.

hen it should be the case that all male Cohen's should have the same Y chromosome, right?

Because keep in mind, any single affair with the milkman or the mailman, over 3,000 years, would've broke this chain of inheritance, any single incidence of non-paternity. It's a really astounding story, and it's hard, there can be no artifact to it, there's no bias in it, there's no other way to explain it.

And what they found was that all members of the, almost all members of the ruling cast among the Lembas, had the same Y chromosome, and the Y chromosome had exactly the same polymorphisms of the Cohen Y chromosome

What I'm telling you is that these two genes are totally interchangeable, that they are effectively indistinguishable from one another, functionally they have some sequence relatedness, but in terms of the way they program development, they are effectively equivalent. And what this means is that the progenitor of these two genes must've already existed at the time that the flies and we diverged, which six or seven-hundred million years ago, and in the intervening six or seven-hundred million years, these genes have been totally unchanged.

once the gene was developed, evolution could not tinker with it, and begin to change it in different ways, ostensibly because such tinkering would render these genes dysfunctional, and thereby would inactivate them, thereby depriving the organism of a critical sensory organ.

horrors of the recent World War

s the factor which disturbs our relations with our neighbor and which forces civilization into such a high expenditure [of energy]

civilized society is perpetually threatened with disintegration

instinctual passions are stronger than reasonable interests.

commandment to love one's neighbor as oneself -- a commandment which is really justified by the fact that nothing else runs so strongly counter to the original nature of man

liverance from our evil

The communists believe they have found  the path to de

Since everyone's needs would be satisfied, no one would have any reason to regard another as his enemy; all would willingly undertake the work that was necessary.

but we have in no way altered the differences in power and influence which are misused by aggressiveness, nor have we altered anything in its nature. Aggressiveness was not created by property

If we were to remove this factor, too, by allowing complete freedom of sexual life and thus abolishing the family, the germ-cell of civilization, we cannot, it is true, easily foresee what new paths the development of civilization could take; but one thing we can expect, and that is that this indestructible feature of human nature will follow at there.

We can now see that it is a convenient and relatively harmless satisfaction of the inclination to aggression, by means of which cohesion between the members of the community is made easier

n this respect the Jewish people, scattered everywhere, have rendered most useful services to the civilizations of the countries that have been their hosts;

find its psychological support in the persecution of the bourgeois

s Civilization imposes such great sacrifices not only on man's sexuality but on his aggressivity, we can understand better why it is hard for him to be happy in that civilization.

primitive man was better off in knowing no restrictions of instinct.  To counterbalance this, his prospects of enjoying this happiness for any length of time were very slender.

Civilized man has exchanged a portion of his possibilities of happiness for a portion of security.

But I shall avoid the temptation of entering upon a critique of American civilization; I do not wish to give an impression of wanting myself to employ American methods.

was the preparation of firing and bombing tables for the Army which at that time, of course, included the Army Air Corps.

The analyzer installed at Aberdeen had ten integrating units and provisions for two input and two output tables as well. But, despite its value as an important mechanical aid to computation, it had several severe limitations.

It was, of course, known that the Moore School of Electrical Engineering of the University of Pennsylvania had a Bush differential analyzer of somewhat larger capacity than the one installed at Aberdeen. As a matter of fact, the one at the Moore School had fourteen integrating units. Therefore one of the first steps taken was the award to the University of Pennsylvania of a contract by the Ordnance Department for the utilization of this device.

he original agreement between the United States of America and the trustees of the University of Pennsylvania, dated June 5, 1943, called for six months of "research and development of an electronic numerical integrator and computer and delivery of a report thereon." This initial contract committed $61,700 in U.S. Army Ordnance funds

The ENIAC was placed in operation at the Moore School, component by component, beginning with the cycling unit and an accumulator in June 1944. This was followed in rapid succession by the initiating unit and function tables in September 1945 and the divider and square-root unit in October 1945. Final assembly took place during the fall of 1945. By today's standards for electronic computers the ENIAC was a grotesque monster. Its thirty separate units, plus power supply and forced-air cooling, weighed over thirty tons. Its 19,000 vacuum tubes, 1,500 relays, and hundreds of thousands of resistors, capacitors, and inductors consumed almost 200 kilowatts of electrical power. But ENIAC was the prototype from which most other modern computers evolved. It embodied almost all the components and concepts of today's high- speed, electronic digital computers. Its designers conceived what has now become standard circuitry such as the gate (logical "and" element), buffer (logical "or" element) and used a modified Eccles-Jordan flip-flop as a logical, high-speed storage-and-control device.

The ENIAC was not originally designed as an internally programmed computer. The program was set up manually by varying switches and cable connections. However, means for altering the program and repeating its iterative steps were built into the master programmer

The ENIAC led the computer field during the period 1949 through 1952 when it served as the main computation workhorse for the solution of the scientific problems of the Nation. It surpassed all other existing computers put together whenever it came to problems involving a large number of arithmetic operations. It was the major instrument for the computation of all ballistic tables for the U.S. Army and Air Force.

1925-1926   Introduction of lightweight, air-cooled radial engines The introduction of a new generation of lightweight, air-cooled radial engines revolutionizes aeronautics, making bigger, faster planes possible.

  1917   The Junkers J4, an all-metal airplane, introduced Hugo Junkers, a German professor of mechanics introduces the Junkers J4, an all-metal airplane built largely of a relatively lightweight aluminum alloy called duralumin.

1904   Concept of a fixed "boundary layer" described in paper by Ludwig Prandtl German professor Ludwig Prandtl presents one of the most important papers in the history of aerodynamics, an eight-page document describing the concept of a fixed "boundary layer," the molecular layer of air on the surface of an aircraft wing. Over the next 20 years Prandtl and his graduate students pioneer theoretical aerodynamics.

1933   First modern commercial airliner In February, Boeing introduces the 247, a twin-engine 10-passenger monoplane that is the first modern commercial airliner. With variable-pitch propellers, it has an economical cruising speed and excellent takeoff. Retractable landing gear reduces drag during flight.

935   First practical radar British scientist Sir Robert Watson-Watt patents the first practical radar (for radio detection and ranging) system for meteorological applications. During World War II radar is successfully used in Great Britain to detect incoming aircraft and provide information to intercept bombers.

1937   Jet engines designed Jet engines designed independently by Britain’s Frank Whittle and Germany’s Hans von Ohain make their first test runs. (Seven years earlier, Whittle, a young Royal Air Force officer, filed a patent for a gas turbine engine to power an aircraft, but the Royal Air Ministry was not interested in developing the idea at the time. Meanwhile, German doctoral student Von Ohain was developing his own design.) Two years later, on August 27, the first jet aircraft, the Heinkel HE 178, takes off, powered by von Ohain’s HE S-3 engine.

  1939   First practical singlerotor helicopters Russian emigre Igor Sikorsky develops the VS-300 helicopter for the U.S. Army, one of the first practical singlerotor helicopters.