Matter Into Energy (Revised, 1978)

foreign [Music] [Music] this is the USS Enterprise it is one of the largest warships that has ever been launched if the Enterprise were stood on end in New York City it would be almost as tall as the Empire State Building yet this giant vessel can race through Heavy Seas at speeds up to 35 knots or 40 miles per hour even more important the Enterprise can cruise for five years without stopping to refuel unlike ordinary ships the Enterprise need not carry bulky supplies of fuel because it is nuclear powered the source of its energy is uranium if we could build a nuclear engine for an automobile one cubic centimeter or about a quarter of a teaspoon of uranium-235 would release enough energy to power the car for over 230 000 kilometers which is the expected lifetime of most cars this incredible amount of energy is derived from the nucleus of the uranium atom even when represented by a simplified model the uranium-235 atom appears large and complex so let's start with the model of a very simple atom helium the small dense center of the atom is called the nucleus it is made up of Two basic kinds of particles protons and neutrons these particles generate many forces between them some pushing and some pulling some simple and some very very complex for example protons have a positive electrical charge neutrons have no electrical charge they are neutral since like charges repel each other why don't the protons fly apart and why don't the neutrons which have no charge at all Drift Away there must be powerful forces holding these particles together they are called nuclear binding forces actually The Binding forces are related to an amount of energy called The Binding energy of the nucleus now think about the nucleus of a uranium-235 atom one of the largest of all atoms its nucleus is a cluster of 235 particles 143 neutrons and 92 protons there are so many forces pushing the 92 protons apart that an enormous amount of binding energy is needed to hold the nucleus together when some of this energy is released it becomes the basic source of power of the USS Enterprise but how is this energy released in a device called a nuclear reactor uranium nuclei are bombarded by free neutrons when one of these free neutrons collides with a uranium nucleus it is absorbed unbalancing the internal structure of the nucleus so it splits into two smaller nuclei freeing a few neutrons this is what it looks like in stop action actually these particles fly apart the nuclear energy that is released goes into the movement of the speeding particles some of the neutrons released then split other uranium nuclei releasing more nuclear energy and still more neutrons thus a chain reaction is started this splitting of the nucleus is called nuclear fission during nuclear fission a curious thing happens to understand it let's weigh this uranium nucleus when an actual uranium atom splits the pieces weigh less than the original nucleus now think about this a little matter disappeared and a large amount of energy appeared is it possible that the matter turned into energy in 1905 a young German physicist announced a bold new scientific theory the young man who was later to become the world's most famous physicist was Albert Einstein he proposed that matter and energy are actually different forms of the same thing furthermore Einstein predicted that matter and energy could be changed into each other according to the Formula E equals m c squared e energy equals m the amount of matter that is changed into energy times c squared the speed of light multiplied by itself the speed of light is 300 000 kilometers per second or 186 000 miles per second when this number is multiplied by itself the result is such an enormous number that if even a tiny bit of matter is converted into energy a tremendous amount of energy is released on the other hand it would take a tremendous amount of energy to produce even a speck of matter for example if all the matter in a one kilogram lump of coal or any other substance could be completely converted into energy it would equal all the electrical energy needed in the entire United States for 60 days but that same enormous amount of energy would be needed to produce the mass in one kilogram of coal with the world gripped in an energy crisis because the Earth's reserves of coal oil and gas are being used up rapidly energy from nuclear fission is becoming increasingly important you have already seen that huge ships can be propelled by nuclear reactors on land nuclear reactors are being constructed in many parts of the world to Supply electrical energy some experts are convinced that it already costs less to generate electrical power from nuclear fuel than from our Vanishing supplies of fossil fuels such as oil coal and natural gas though many feel that there are serious problems with nuclear power plants scientists and Engineers are working to overcome the problems their research and development May provide the world with a safe reliable and economical source of energy for many years to come it's hard to imagine a greater source of energy than nuclear fission but there is such a source it is the power source of the sun itself the sun's energy also comes from changing matter into energy but in a different way this process called nuclear fusion goes on constantly in the Sun by several series of complicated nuclear reactions in one of these series The Net result is the nuclei of four hydrogen atoms Each of which is simply a proton combined or fuse releasing a tremendous amount of energy and forming a helium nucleus but now let's see what happens to the mass of the four hydrogen nuclei each nucleus has a mass of about 1.008 units so the total combined mass of the four nuclei is 4.032 but when Fusion takes place the mass of the resulting helium nucleus is only 4.003 units wait a minute shouldn't the mass of the helium nucleus be 4.032 by subtracting the mass after Fusion 4.003 from the mass before Fusion 4.032 you discover that during Fusion 0.029 units of mass disappeared but a large amount of energy was produced so in both fission and fusion matter is converted into energy so far the hydrogen bomb is the only way that man has learned to use energy through Fusion but scientists are now learning to control and harness the nuclear fusion of hydrogen atoms taken from water if and when they Master the process we will have a source of energy as vast and unlimited as the Seas themselves foreign