This post is the next in a series that dates back several years. In fact, it's been going on for long enough that several posts ago I decided to upgrade from "50 Years of Science" to "60 Years of Science". And, if we group them together, this is the nineteenth main entry in the series. You can go to https://sigma5.blogspot.com/2017/04/50-years-of-science-links.html for a post that contains links to all of the entries in the series. I will update that post to include a link to this entry as soon as I have posted it.
I take Isaac Asimov's book "The Intelligent Man's guide to the Physical Sciences" as my baseline for the state of science when he wrote the book (1959 - 60). In this post I will be reviewing two sections. "Electricity" and "Electrical Gadgets" are both from the chapter titled "The Machines".
In "Electricity" Asimov goes all the way back to the ancient Greeks. Amber, the material, can attract feathers, threads, bits of fluff, and other light things, if it is rubbed with fur. The Greek word for amber is "elektron" and that's where we get the name for the subatomic particle. Many centuries later Gilbert decided to call whatever it was that caused the attraction "electricity". And he noted that other materials, particularly glass, could be induced to perform the same trick.
In 1733 du Fay discovered that two rods of the same material, when suitably rubbed, would repel each other. He also noted that two similar rods, when allowed to come in contact with each other, would lose their electrical property.
Franklin was the most famous early investigator of electricity and its properties. He suggested that it was a fluid. He opined that "positive" electricity was caused by a material containing a surplus of electricity and that "negative" electricity was cause by a shortage. Electric fluid would then naturally flow from positive to negative.
It turns out that in most circumstances electrical flow is the result of the movement of electrons. Franklin had nothing concrete to go on so his decision about what was "positive" and what was "negative" was arbitrary. And, as luck would have it, he got it backwards. Electrons flow from the negatively charged material to the positively charged material.
But, in the long era of electronic devices based on vacuum tubes, successful designs required that the power supply to provide a positive voltage to the circuit. It was only with the change to solid state "transistorized" designs that power supply designs were changed to provide a negative voltage to the circuit. So, for a long time, from a practical perspective Franklin had the right of it.
In 1740 Desaguliers suggested that the pipe through which electrical fluid flowed be called a "conductor". On the other hand, materials that blocked flow would be called "insulators". Experimenters of the time found that a modest quantity of electrical fluid could be stored using a suitable device.
A popular early device of the time was the Leyden jar, so called because it was developed in 1745 at the University of Leyden. This was created by coating the inside of a glass jar (insulator) with metal foil (conductor). This design is still in use today in the "capacitor", a common electronic component.
Leyden jars could only hold modest amounts of electricity. (Not surprisingly, modern capacitors do much better.) But it was enough to allow for experimentation. It was possible to create sparks and to get them to jump small gaps. They could also produce a shock in a person or an animal. It was natural to conjecture that thunder and lightning might be caused by much larger quantities of electricity. Franklin was famous for coming up with an experimental method for determining if this was correct.
He flew a kite during a thunderstorm. The silk thread he used as a kite string, when wet, became a poor but adequate conductor. He attached a key to the string because it was known that sparks liked to jump from sharp points. The experiment worked.
He managed to shock himself using electricity produced by a thunderstorm without getting killed. (It was a good thing the silk cord was a poor insulator.) Others who duplicated Franklin's setup were killed. But the connection between Leyden jar electricity and thunderstorm electricity was firmly established. The difference was merely in the matter of the amount, not the kind.
Electricity stored in a Leyden jar is "static" electricity. It's not flowing. Things get more interesting when it flows, when it becomes "dynamic" electricity. In the same way Franklin established the connection between Leyden jar electricity and thunderstorm electricity, Galvani began the exploration of how electricity is used by living creatures. Famously, he stimulated the muscles in the legs of dead frogs to twitch by applying electricity to them.
He used an improvement on the Leyden jar called the "Voltaic Pile". Volta stacked discs made of copper then zinc then fabric soaked in brine on top of each other repeatedly. This could produce much more electricity than the Leyden jar. And it could produce it continuously for long periods of time.
This "anode", "cathode", and "electrolyte" design is how batteries are made to this day. As with modern capacitors, modern batteries work much better than Volta's original Pile. But the primary principal is exactly the same.
As all cell phone owners know, even the best battery runs down eventually. What was needed was a way to turn mechanical energy into electricity. Faraday was the first to figure out how to do this. His "dynamo-electric machine", generally shortened to "dynamo" and often referred to as a "generator" provided a proof of concept.
But it didn't work all that well. The weak spot was the magnet used. Wheatstone solved the problem in 1845. He replaced the permanent magnet of Faraday's original design, with an "electromagnet", a device developed by Henry.
The magnetic field was produced by wrapping many turns of wire around a piece of iron then running electricity through the wire. Each turn produced only a weak magnet. But the close proximity of the turns, and their large number, caused them to combine and produce a magnetic field that was much more powerful than the one a permanent magnet could produce.
The combination of a steam engine and a dynamo made it possible to produce large amounts of electricity on demand. Now, what to do with it? Henry of electromagnet fame stepped in with one of the first ideas, the telegraph. "Telegraph" essentially means "writing at a distance". The electric telegraph was only the latest in a long line of devices used for this purposes. The original version was perhaps the "signal fire" or maybe "smoke signals".
When Henry's design came along, ships had been communicating across miles of oceans using "signal flags". One ship could read another ship's "flag hoist" by using a telescope. Land systems using large arms that could be positioned in various configurations, and other similar systems, could also be read across a distance of miles using a telescope. These systems were popular during the Napoleonic Wars.
Henry's telegraph design started with the "key", essentially a switch that could be used to turn electricity off and on quickly and easily. That was connected by a long wire to a "sounder", a device that emitted a loud "click" when the current was turned off or on. He also developed the "repeater", essentially a sounder connected to a key. Wires of the time were poor. So the electrical signal diminished quickly with distance.
At a distance where the electrical signal was weak but still usable the repeater would use the remaining weak signal not to make a click but to operate a key hooked to a new wire that was charged using a new power supply. The message was thus repeated several times to greatly expand the usable range of the telegraph system without needing to station a human operator every few miles. This system allowed electric "telegraph lines" to be operated over distances that were long enough to make them useful.
Samuel F. B. Morse added an efficient coding system in 1844, Morse Code. It used short sequences of dots and dashes to represent common letters like "E", and long sequences for uncommon letters like "Q". Morse Code provided the last piece necessary to made the whole enterprise feasible. "What hath God wrought" was the inaugural message transmitted via electric telegraph.
Henry was also the first to come up with a design for an electric motor. It was again more of a proof of concept than a useful device. But, unlike the steam engine, it could be turned off and on quickly. More, importantly, now a dynamo could be used to turn power from a steam engine into electricity and an electric motor could used to reverse the process.
Asimov finishes the section by noting that moving electricity around via wires, "transmitting" it from one place to another, was initially very inefficient. One trick for improving the situation was the introduction of the "transformer". It can be used to transform the combination of a low voltage and a high current into the combination of a high voltage and a low current. Generally speaking, low currents result in smaller losses as the electricity moves along the wire.
Transformers only work if the electricity is in the form of "Alternating Current". With AC, both the voltage and the current alternate up and down quickly. With "Direct Current", the voltage and current stay relatively constant. Edison was a proponent of DC. But he never figured out how to move DC power over significant distances. Westinghouse championed AC. The flexibility that AC transformers made possible made it become the standard.
Edison invented and then championed the "Electric Chair" as a "humane method of execution". It was anything but. People were supposed to be so horrified by executions using an electric chair powered by AC that they would force AC's abandonment. Edison kept his role in all this secret. And the scheme failed.
One reason was that Tesla, originally an Edison employee, defected to Westinghouse after Edison treated him shabbily. He developed many of the components a full AC system needed. Following in Tesla's footprints, Steinmetz, an employee of General Electric, developed a complete theory for AC that put it on a firm mathematical basis and allowed others to exploit it more fully. On to "Electrical Gadgets".
The telegraph was an early electrical gadget. But it was what we would now call a "text based" method of communication. In 1876 Bell made it possible to use electricity to transmit the spoken word. And that meant music and all kinds of other sounds could be transmitted too. In 1877 Edison followed up with the "phonograph". That made it possible to record sounds for later playback.
It also made possible the mass duplication and sale of identical "records". This extended to the realm of sound the role that books and newspapers had long played in the text based realm. For the first time, many people could hear the same sounds in many places and at many times. That had never been possible before.
Berliner took Edison's cylinders, originally made from tin foil, later made from lacquer, and replaced them with the much handier flat disk that we now associate with the "phonograph record".
By 1925, electrical components were being introduced at various stages into a process that had previously been 100% mechanical. Various inherent limitations meant that purely mechanical systems were unable to produce a sound much above that of a whisper.
The introduction of electrical components, permitted the sound to be "amplified", made louder. There was essentially no limit to the amount of amplification possible. Soon it became possible to use "loud speakers" to transmit the same sounds to a large crowd, say at a baseball park.
The early equipment was limited in both the quantity and the quality of this sound amplification. But as time went by these limitations diminished. By the time Asimov wrote his book "hi-fi" (high fidelity) had been introduced. This produced natural sounding recordings of everything from birdsong to symphony orchestras. "Stereo", two audio channels instead of one ("monaural"), was introduced just a few years before the book came out.
At the time of the book the best method of sound reproduction available is what we would now call "analog". A needle in the grove of a record moved up and down as it tracked the varying depth of the groove. The movement of the needle was amplified using various mechanical tricks to produce the sound that came out of the attached "horn". Even the best design produced a weak sound because there was little energy to be derived from the needle's movement.
Electricity immensely improved the situation. The needle could be attached to a device that translated needle movement into a variation in an electrical signal. Amplification could then boost the power. This could then be fed into speakers that could translate the now much more powerful electrical signal into a powerful air movement, a loud sound.
With the need to be mechanically connected to a horn removed much more delicate needle movements could be used. A clever design change allowed one side of the grove be tracked to produce the signal for the "left channel" while the other side of the groove was independently tracked to produce the signal for the "right channel". Two channels were now available to produce stereo output. But this technique could only be used to produce two channels.
Sound reproduction has since moved to using "digital" formats. Various methods can be used to encode and store the long sequence of numbers that represents even a short digital recording. It can be stored on a CD, something that at first glance appears to be similar to a phonograph record. But anywhere large amounts of numbers can be stored, and any way that large amounts of numbers can be transmitted, can now be used.
And, if you have enough computing capacity available, any number of "audio channels" can be carried around. The popular "5.1" format requires six channels of audio data, for instance. The "5" is for the five high frequency channels and the ".1" is for the sixth, low frequency (base) channel.
Another alternative to the "needle in a groove" method of recording audio was the "tape recorder". The technology is actually older than the radio. It was first demonstrated by Poulson in 1898. But it didn't come into widespread use until after World War II. A wire, then later a plastic ribbon, was coated with a goo containing particles whose magnetic properties could be manipulated.
A powerful moving magnet could be used to "record" (change the alignment of the poles of the magnetic particles to conform to a specific pattern) a signal then later "play back" (use another, less powerful magnet and some sensitive electronics, to detect and amplify) whatever pattern of sounds you wanted. Various tape based recording methods persisted for audio until about 1990 and for video for a decade or so longer.
So all this sound business is nice but what about light? The arc light was the first method used to change electricity into light. It involved using high voltage electricity to burn carbon rods at high temperature. It was not practical for most uses. The first practical light bulb was the one Edison designed in 1879. It heated a "filament" until it was literally white hot. Edison was the first to produce a device that was small, cheap, safe, and could be manufactured in large quantities.
His design is for what we now call an "incandescent" device. It is wildly inefficient. Most of the electrical energy goes into producing useless heat. A more efficient design is the "fluorescent" tube, which dates from 1936. It works by smashing high energy electrons into the side of a tube that is coated with a phosphor that lights up under this insult. Surprisingly, this design is about three times as efficient as the incandescent design. But it is hard to get the phosphors to glow with the kind of soft, warm, inviting light that incandescent lights put out.
When the book came out incandescent and fluorescent were pretty much the only options for use in most situations. Since then the LED (Light Emitting Diode) light has become available. I am not going to go into how they work. But they do. And they are capable of producing the warm light that we love in an incandescent.
At the same time they are also about three times efficient as a fluorescent. And, since they don't get hot, they tend to last forever. So they cost more to buy in the first place. But they save money by using far less electricity and because they take a very long time to "burn out". Fluorescent lights burn out much more quickly. Incandescent lights burn out even more quickly than fluorescent lights.
So what else? Photography is "what else". The first recognizably modern stabs at photography happened in 1839 and were originated by Talbot and, more famously, Daguerre of Daguerreotype fame. Improvement followed improvement. Asimov goes through this briefly but I am going to skip it because it's chemistry and we are talking electricity.
In parallel with these developments was an investigation of how to capture motion. The key insight was made in 1824 by Roget. He noticed that the eye forms a persistent image, one that persists for a small period of time after the image is removed. Various people tried to exploit this to produce "moving pictures". Asimov skips over the famous "trotting horse" demonstration, assembled by Eadweard Muybridge in 1878 to prove a bet, that is widely considered the first moving picture. Instead, he moves on to Edison.
Edison produced the first successful moving picture camera and projector. By this time others had produced a type of film that was suitable for use with Edison's equipment. And significant to our story is the fact that his projector used electricity to produce the light that was "projected" onto a screen where the "movie" could be viewed by an audience.
The first commercial exhibition of a movie was in 1894. the first full length "motion picture" premiered in 1914. But what was missing at this time was sound. Initially, sounds were recorded using standard phonograph record technology. A synchronization system was supposed to keep the record in sync with the film. But even though "The Jazz Singer", the first successful "sound movie", used this method in 1927, the system never worked very well.
Advances in electronics, and clever design, soon moved the "sound track" to a band adjacent to the pictures on the same piece of film that held the "moving" pictures. Advances in chemistry allowed movies to routinely incorporate color by the 1930s. Eventually the "black and white" movie became uncommon.
And that's where things stood when Asimov wrote his book. Other than the additions necessary to record then eventually broadcast sound, the movie camera and projector remained unchanged from Edison's original designs. And the movie was the best technology for producing high quality moving images.
But at about the time that the book came out audio tape recording technology had improved enough to be good enough for use with moving images. Initially, it was barely good enough to record and play "TV quality" black and white images. And the equipment and video tape were expensive and difficult to work with. But technology marched on.
Soon (the early '60s) the technology got good enough to use routinely in professional situations. Shortly thereafter (the late '60s) it became good enough for routine use in professional situations with color images.
Then a decade or so later, the consumer VCR (Video Cassette Recorder) became cheap enough and easy enough to use that it became a standard staple in many households. This allowed movies to be transferred to video tape cassettes and sold to consumers. Some "cult" movies made more money from cassette sales that they did from their theatrical run.
Producers of pornographic movies soon jumped on the bandwagon. Movie theaters that were willing to show "XXX" movies initially did not exist. Then they were confined to a few seedy theatres in run down neighborhoods in big cities. This, and the fact that XXX movies were soon forbidden from advertising in most newspapers, made it impossible to make big money on a pornographic film.
But it turns out that people in large numbers all over the country were willing to buy XXX video cassettes. Now it became possible to sell millions of dollars worth of cassettes of a particularly popular XXX movie. This made the producers of "Deep Throat", for instance, into multi-millionaires.
Soon stores renting movies on cassette became popular. Most people were only interested in viewing a movie once. So they were very selective when it came to shelling out $80 for a movie. But a video rental store could rent that same $80 movie out 50 or 75 times at $2 a pop and make a nice profit. And in the early days pretty much every video rental store had an XXX section in the back.
As with everything else, digital eventually intruded. Computer, and later home based "Personal Computer" equipment became available at progressively lower and lower prices and higher and higher quality. Digital CCD (Charged Coupled Device) components became available at a price and quality that made them appropriate for incorporation into a camera. LED and other "solid state" components became available at a price and quality that made them appropriate for incorporation into a projector.
And, of course, the computer processing, data storage, and data transportation, components also became available at at a suitable price and quality point that allowed everything to be connected together. The CD with its audio quality that was superior to a phonograph record was the first "digital media" to be successfully introduced.
Laserdisks had far less commercial success in the video realm than CDs did in the audio realm for reasons I am going to skip over. But they too produced a product that was of higher quality than the competing video cassette. In spite of the commercial failure they represented, they still managed to pave the way for the highly successful DVD (Digital Video Disk).
And the eventual wide availability of home high speed internet connections made it possible to "stream" a movie rather than buy or rent it. Internet streaming has almost completely killed the buy/rent options. And both the picture and sound quality that can be delivered into the home is now much higher than the best that was available when Asimov's book came out, even if you went to a movie theater.
There is much more that could be said about electrical gadgets. But Asimov stops here so I will too.
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