The Feynman Lectures on Physics Vol. I Ch. 3: The Relation of Physics to Other Sciences
Science and Technology. Physics. Science: General · Physics · Physics: Biographies · Weights and Measures. See also: Science and Technology. The Relationship between Science and Technology. Discussion Document prepared for the New Zealand Ministry of Education Curriculum Project. Dr Vicki. the History of Science and technology Held in London from June 29th to July 3rd, by There is a very close relationship between physics and industry.
Space science can also include the history of spaceflight and exploration.
It's basically the study of everything related to space, including where and how life might form in places other than Earth. Physics is integral to space science, because if we don't understand how our universe works, we can't begin to explore it.
We had to understand that the Moon was a body that orbits the Earth before we could even think of going there. We also had to understand the laws of gravity and the distances and movement between bodies in space before we could successfully build a rocket to get anywhere and back. Sending shuttles into space would not be possible without physics Understanding the compositions of stars and planets, and how they form, allows astrobiologists to talk competently about the elements that may be present in different parts of the solar system.
The technologies we use to communicate with astronauts also came as a result of discoveries in physics. In a very real way, all of space science is reliant on physics.
There the nerve branches out into fine little things, connected to a structure near a muscle, called an endplate. For reasons which are not exactly understood, when the impulse reaches the end of the nerve, little packets of a chemical called acetylcholine are shot off five or ten molecules at a time and they affect the muscle fiber and make it contract—how simple!
What makes a muscle contract? A muscle is a very large number of fibers close together, containing two different substances, myosin and actomyosin, but the machinery by which the chemical reaction induced by acetylcholine can modify the dimensions of the muscle is not yet known.
Thus the fundamental processes in the muscle that make mechanical motions are not known. Biology is such an enormously wide field that there are hosts of other problems that we cannot mention at all—problems on how vision works what the light does in the eyehow hearing works, etc. The way in which thinking works we shall discuss later under psychology.
Now, these things concerning biology which we have just discussed are, from a biological standpoint, really not fundamental, at the bottom of life, in the sense that even if we understood them we still would not understand life itself. But you can have life without nerves.
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Plants have neither nerves nor muscles, but they are working, they are alive, just the same. So for the fundamental problems of biology we must look deeper; when we do, we discover that all living things have a great many characteristics in common. The most common feature is that they are made of cells, within each of which is complex machinery for doing things chemically.
In plant cells, for example, there is machinery for picking up light and generating glucose, which is consumed in the dark to keep the plant alive. When the plant is eaten the glucose itself generates in the animal a series of chemical reactions very closely related to photosynthesis and its opposite effect in the dark in plants.
In the cells of living systems there are many elaborate chemical reactions, in which one compound is changed into another and another. To give some impression of the enormous efforts that have gone into the study of biochemistry, the chart in Fig. Here we see a whole series of molecules which change from one to another in a sequence or cycle of rather small steps. It is called the Krebs cycle, the respiratory cycle.
Each of the chemicals and each of the steps is fairly simple, in terms of what change is made in the molecule, but—and this is a centrally important discovery in biochemistry—these changes are relatively difficult to accomplish in a laboratory. If we wanted to take an object from one place to another, at the same level but on the other side of a hill, we could push it over the top, but to do so requires the addition of some energy.
Thus most chemical reactions do not occur, because there is what is called an activation energy in the way. In order to add an extra atom to our chemical requires that we get it close enough that some rearrangement can occur; then it will stick.
However, if we could literally take the molecules in our hands and push and pull the atoms around in such a way as to open a hole to let the new atom in, and then let it snap back, we would have found another way, around the hill, which would not require extra energy, and the reaction would go easily.
Now there actually are, in the cells, very large molecules, much larger than the ones whose changes we have been describing, which in some complicated way hold the smaller molecules just right, so that the reaction can occur easily. These very large and complicated things are called enzymes. They were first called ferments, because they were originally discovered in the fermentation of sugar.
In fact, some of the first reactions in the cycle were discovered there. In the presence of an enzyme the reaction will go. An enzyme is made of another substance called protein.
Enzymes are very big and complicated, and each one is different, each being built to control a certain special reaction. The names of the enzymes are written in Fig. Sometimes the same enzyme may control two reactions. We emphasize that the enzymes themselves are not involved in the reaction directly. They do not change; they merely let an atom go from one place to another.
Having done so, the enzyme is ready to do it to the next molecule, like a machine in a factory. Of course, there must be a supply of certain atoms and a way of disposing of other atoms. Take hydrogen, for example: For example, there are three or four hydrogen-reducing enzymes which are used all over our cycle in different places. It is interesting that the machinery which liberates some hydrogen at one place will take that hydrogen and use it somewhere else.
The most important feature of the cycle of Fig. So, GTP has more energy than GDP and if the cycle is going one way, we are producing molecules which have extra energy and which can go drive some other cycle which requires energy, for example the contraction of muscle. The muscle will not contract unless there is GTP. An enzyme, you see, does not care in which direction the reaction goes, for if it did it would violate one of the laws of physics.
Physics is of great importance in biology and other sciences for still another reason, that has to do with experimental techniques.
In fact, if it were not for the great development of experimental physics, these biochemistry charts would not be known today. The reason is that the most useful tool of all for analyzing this fantastically complex system is to label the atoms which are used in the reactions.
They are different isotopes. We recall that the chemical properties of atoms are determined by the number of electrons, not by the mass of the nucleus. But there can be, for example in carbon, six neutrons or seven neutrons, together with the six protons which all carbon nuclei have. Now, we return to the description of enzymes and proteins. Not all proteins are enzymes, but all enzymes are proteins. There are many proteins, such as the proteins in muscle, the structural proteins which are, for example, in cartilage and hair, skin, etc.
However, proteins are a very characteristic substance of life: Proteins have a very interesting and simple structure. They are a series, or chain, of different amino acids. There are twenty different amino acids, and they all can combine with each other to form chains in which the backbone is CO-NH, etc. Proteins are nothing but chains of various ones of these twenty amino acids. Each of the amino acids probably serves some special purpose. Some, for example, have a sulfur atom at a certain place; when two sulfur atoms are in the same protein, they form a bond, that is, they tie the chain together at two points and form a loop.
Another has extra oxygen atoms which make it an acidic substance, another has a basic characteristic. Some of them have big groups hanging out to one side, so that they take up a lot of space. One of the amino acids, called proline, is not really an amino acid, but imino acid.
There is a slight difference, with the result that when proline is in the chain, there is a kink in the chain. If we wished to manufacture a particular protein, we would give these instructions: In this way, we will get a complicated-looking chain, hooked together and having some complex structure; this is presumably just the manner in which all the various enzymes are made.
One of the great triumphs in recent times sincewas at last to discover the exact spatial atomic arrangement of certain proteins, which involve some fifty-six or sixty amino acids in a row.
Over a thousand atoms more nearly two thousand, if we count the hydrogen atoms have been located in a complex pattern in two proteins. The first was hemoglobin. One of the sad aspects of this discovery is that we cannot see anything from the pattern; we do not understand why it works the way it does. Of course, that is the next problem to be attacked. Another problem is how do the enzymes know what to be?
A red-eyed fly makes a red-eyed fly baby, and so the information for the whole pattern of enzymes to make red pigment must be passed from one fly to the next.
This is done by a substance in the nucleus of the cell, not a protein, called DNA short for desoxyribose nucleic acid. This is the key substance which is passed from one cell to another for instance sperm cells consist mostly of DNA and carries the information as to how to make the enzymes.
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First, the blueprint must be able to reproduce itself. Secondly, it must be able to instruct the protein. Concerning the reproduction, we might think that this proceeds like cell reproduction. Cells simply grow bigger and then divide in half. Must it be thus with DNA molecules, then, that they too grow bigger and divide in half? Every atom certainly does not grow bigger and divide in half!
No, it is impossible to reproduce a molecule except by some more clever way. Schematic diagram of DNA. The structure of the substance DNA was studied for a long time, first chemically to find the composition, and then with x-rays to find the pattern in space.
The result was the following remarkable discovery: The DNA molecule is a pair of chains, twisted upon each other. The backbone of each of these chains, which are analogous to the chains of proteins but chemically quite different, is a series of sugar and phosphate groups, as shown in Fig. Thus perhaps, in some way, the specific instructions for the manufacture of proteins are contained in the specific series of the DNA.
Attached to each sugar along the line, and linking the two chains together, are certain pairs of cross-links. Whatever the letters may be in one chain, each one must have its specific complementary letter on the other chain. What then about reproduction? Suppose we split this chain in two. How can we make another one just like it? This is the central unsolved problem in biology today. We still use glass in our windows and electric lamps which cut off the highly important ultraviolet rays.
Powerful beams of high-speed electrons or protons and concentrated electro-magnetic waves could find considerable application within the chemical and electrical industries. The limiting stresses which a physical body can stand were found to be much in excess of the limits actually reached. For instance, we are able to state that an electrical breakdown could be prevented up to a field of over one hundred million volts per centimeter, while we still use a field of forty thousand volts.
We have also increased the mechanical strength of crystals many hundreds of times. We have succeeded in discovering substances with an electric constant of over 20, while no more than ten are used. An extensive field of investigations is awaiting exploration in order to make the results available to technique. The sensitiveness of the methods developed by physics and chemistry is very striking. We can detect a single electron and proton, and less than one hundred photons of ultra-violet and even visible light.
X-Rays and electron rays analysis reveal the finest details of structure. Wireless waves can be detected after they have travelled a hundred thousand miles. Why have we not adapted these methods to use in everyday life?
There are innumerable other such problems. I am convinced physicists are wrong in neglecting them. Not only would their investigations be of practical use, but they would lead to the development of new problems, would lay bare new features of phenomena known to us only under one aspect.
Thus set to work, our interest would lead to a further theory and thence to further experiments, all regarded from one aspect supplied by its origin. New light would be thrown on the old problems and new points of view could be expected as the result of an independent course of research.
We are glad that in our own country we have removed all obstacles to an undisturbed development of science closely bound up with the building of a new future.
We have some two thousand physicists. We hope to have the co-operation of millions of workers who are enthusiastic about improvement in their industry and about learning. We do not pursue the policy of keeping the population from science by giving them alcohol, by keeping them 75 per cent. The more we proceed with improvements in the standard of living, in shortening the hours of work, in increasing the interest in science and art, the more real will become the co-operation of millions of workers in science and technique.
By building up the industry of to-day science will simultaneously be working on the great problems of the future.