Introduction
Several monumental events happened in the 1860's: The land-grant university act was established in 1862. The assassination of Abram Lincoln happened in 1865, and James Clerk Maxwell's equations were published by the British Royal Society in the same year. The birth of Purdue Engineering and the land-grant universities in America happened around the same time. Therefore, the birth of Purdue University and many land-grant universities roughly coincides with the beginning of 150 years of electromagnetics technologies. These technologies were primarily governed by Maxwell's equations. This set of equations, consisting of four major equations, have set the stage for engineering science for the next 150 years approximately, even though Maxwell has a relatively short life span (1831-1879).
The First 50 Years!
These equations, in the notation used by Oliver Heaviside, are:1
∇×H = ∂D/∂t + J
∇×E = -∂B/∂t
∇·B = 0
∇·D = ρ
Simple though they look to the experts, they have been the harbinger of modern electrical and electronic engineering.2
In the beginning, they were the foundational theory that gives rise to electrical circuits theory such as Kirchhoff circuit law and Kirchhoff voltage law. Later, they yielded Faraday's law (1831), Ampere-Maxwell law (1855), and Gauss' law for magnetic flux as well as electric flux.
In the early days (1820), these laws were motivated by experimental measurements: it was found that when current flows in a loop, it gives rise to magnetic flux, or
∇×H = J
This law was known as Ampere's law.
Then it was discovered that time-varying magnetic flux gives rise to electric field that gives rise to voltage. This law was known as Faraday's law. It was realized that this voltage can be used to drive electric current through a wire even though the wire has a small resistance. The fact that a current flowing through a small resistance gives rise to a voltage drop was known as Ohm's law. When voltages are summed over a closed loop, they add up to zero giving rise to Kirchhoff's voltage law (KVL). Then it can be shown that divergence of J=0 assuming that the frequency was very low. This law was known as Kirchhoff's current law (KCL). These two laws, KVL and KCL are the fundamentals of circuit theory: circuit theory has been the driver of electrical engineering for over a hundred years now.3
One of the early technologies that emerged from electromagnetics was telegraphy. Telegraphy, as the name suggests, was important for telegraphy technology. Telegraphy was used to transmit information long distance via the use of telegrams and Morse codes. Telegraphy also allowed the transmission of information using telegraph cables. As early as the 1800's, these cables were laid under the ocean from Britain all the way to Hong Kong on the rim of South China Sea. With a turn of a switch, Queen Elizabeth could send a telegraph signal all the way from London to Hong Kong. In 1871.4
What is more interesting was that the original four equations of electricity and magnetism were incomplete. For instance, it could not explain why electric current can flow through a capacitor. To complete the equations, and make them consistent with circuit theory and charge conservation, James Clerk Maxwell added a displacement current term to Ampere's law.
∇×H = ∂D/∂t + J
Only with this modified Ampere's law, also called generalized Ampere's law by some authors, did electromagnetic theory was complete. One can show the emergence of wave theory from the completed electromagnetic theory. These equations have been shown to be valid from atomic lengthscale to galactic lengthscale. They can be used to calculate the interaction of electromagnetic field with protons and electrons inside an atom. Also, many of these are subatomic particles whose sizes are much smaller than the atoms; hence, it is accepted that electromagnetic theory is valid down to subatomic lengthscale.
In addition, many of these subatomic particles have spins, with dipole moments like that of a small magnet. These dipole moments have been calculated using theoretical physics methods. They have proved these dipole moments are validated to high precision showing the validity of electromagnetic theory.5 Electromagnetic theory has also inspired special relativity, implying that the speed of light in vacuum is a universal constant. This also implies that Maxwell's remains the same irrespective of what inertial reference frame the measurement was done to validate the theory. Therefore, electromagnetics theory has been validated from subatomic lengthscale to galactic lengthscale. At the present moment, it has been used for nano-lithography to intergalactic communications.6
The Birth of Electrical Engineering and Computer Technology!
Maxwell's equations allow engineers and scientists to manipulate the flow of electrons which is electricity. This was the beginning of electrical engineering. Electricity was then generated by voltaic cells that used chemistry to generate electricity. Then electric generators were later invented to convert mechanical motion into electricity. This allowed engineers to harness the power of steam engine, turbine, windmills to generate electricity. Electricity operates in reverse can operate a motor.
Electricity was then used to power telegraphy which requires switching technology to generate the Morse codes. Switching technology requires nonlinear circuits, and vacuum tube was one such a device. Electronics came about after vacuum tubes. Vacuum tubes, with its ability to rectify and amplify signals, gave rise to the birth of radio engineering. Vacuum tubes consumed too much power, which later motivated the invention of energy-efficient diodes, transistors, and nonlinear circuits as rectifier and amplifiers. Transistor electronics were too noisy in the beginning, but advances in materials, high quality electronics were produced.
Then it was realized that the basic unit of information was a ''bit'' by Shannon.7 It gives rise to the need to store information as bits of signals, or in terms of digital signals. Then information needs to be transmitted in bits of signals in terms of 1's and 0's, called digital signals, rather than continuous signals called analog signals. In digital signals, the amplitudes of the signals are coded in binary numbers. Then, they are converted to precise digital signals. Hence, intuitively, one surmise that digital signals need more bandwidth to transmit a signal. The bandwidth is needed to ensure the precision in the signals. Parity check methods are used to ensure that the sequence of digital signals are precisely transmitted. As we enlarge our knowledge to manipulate digital signals, then came the age of computer and information science.
Information and Communication Technology!
Because of the broad frequency range, and the validity of electromagnetic theory, it has been used from classical electromagnetics to quantum electromagnetics. Electromagnetic sources from kilo-hertz to mega-hertz have been used very early days in radio wave engineering. They can carry voice signals as well as music; they have greatly enrich the lives of humanity. Another great gift of electromagnetics is its use in communication. Humans can now communicate with each other almost at the speed of light. Electromagnectics can carry a signal that goes the planet Earth about 7 times per second. This is almost instantaneous in many applications. Because of this, collaborators can now discuss ideas as if they are next door to each other, greatly enriching the international collaboration. This would not have been possible if our planet Earth was large. Via the use of the Internet, researchers and scholars can have video meetings for international synergy and interaction that change how we collaborate internationally. Some scholars tout this as that ''the Earth is flat'' due to our proximity to each to other after the coming of the Internet. For instance, manufacturing projects can now be designed in one part of the world, and then almost instantly made in another part of the world.
Nanotechnology And Lithography!
Nanotechnology8 has been an important driver in the growth of many modern technologies. It intrinsically capitalizes on the growth of nano-lithography. Our hair is about tens of micrometers, but we can engineer a cube or a transistor that has dimension of a few nanometers. As a consequence, we can pack millions of transistors in the space as small as a strand of hair. Hence, memory has become very cheap because memory chips can now be made extremely small amortizing their cost of production. This compounding effect of exponential growth in memory capacity has made them almost free. Some companies like Google are giving out email accounts for free.
Computers and Computational Technologies!
Because of the growth of modern technologies, computers can now compute a lot faster. More memory and computational power can be packed into a smaller space. In the beginning, computers made of vacuum tubes, because of their sizes, can easily fill a room. But with growth of nano-technologies, now a cell phone that everyone carries can have billions of transistors. That is almost as numerous as the number of neurons that God has given us in our brain. These computers can perform calculations at lightning speed. Growth of lightning speed of computations and algorithms have allowed problems, that take years to simulate, can now be done in a short while. One important consequence of this is the popular demand to replace real experiments in the lab with virtual prototyping, and digital twins to reduce design turn around times. This has spurred the growth of computational electromagnetics that in which my colleagues at Purdue, Dan Jiao, Luis Gomez, and Thomas Roth, are performing world-class research. Rise of rapid computers has spurred another important growth: artificial intelligence (AI). Because computers can now compute a lot faster, and memory is a lot cheaper, data-driven expert systems, the new AI, are in vogue. These systems can work a lot faster than the human mind, and hence, have great potential in replacing the meaning of ''work'' in the modern world.
The Next 50 Years!
I have summarized what has happened approximately in the last 150 years. It is harder to project what is going to happen in the next 50 years. By studying the knowledge we have created in the last 150 years, we have many unsolved problems that we can embark on solving in next 50 years. Many problems remain unsolved, and it will be foolish for me to conjecture what their solutions are. It will be more stimulating to list what these unsolved engineering problems are and challenge all to solve them:
1. Quantum technology and information science.
2. Biotechnology and bio-engineering.
3. Global warming, environmental sustainability.
4. Eradication of corruption, human poverty and inequality.9
5. Eradication of human tribalism, racism, and penchant for violence.10
The above are earthly problems affecting us. One can also think of heavenly problems such as space travel, and colonization of other planets and space. To me, the earthly problems are more important than heavenly problems!
1. Quantum technology and information science: We humans have constant quest for technologies that help us solve problems in exponential faster time. Quantum computers offer such possibilities. Quantum communications and quantum networks promises communication of exponentially large data set in a finite time.
2. There are many unsolved problems in biotechnology, such as ''why is the human brain so efficient in energy consumption compared to modern digital computers?'' The human brain consumes about 25 watts of power while a modern digital computer consumes thousands of watts of power to perform the same task.
3. Due to negligence of the human species, we have spewed over 40 Gigatons of CO2 into our atmosphere.
Eradicating Poverty, Promoting Equality, Peace, and Global Colloboration!
China, with accumulated wisdom over five millennium, has a tradition of managing large projects. She has used her wisdom to lift 800 million people out of poverty. The human mind is one of the greatest natural resources and a gift of God just as technology. Peoples of the world should collaborate to save our planet from global warming.
Short Bio of W.C. Chew:
I am glad to have lived in the last 70 years, the period of most rapid whirlwind technological change in human history. I grew up in the developing world in Malaysia with no running water, and I first saw radio when I was six-year old in our neighbor's house. Then I learned to build my first vacuum tube and transistor radios when I was a teenager. I lived through the era of Sputnik, and later, the moon landing by Neil Armstrong. As I grew up, I programmed the early punch-card IBM main-frame computer at MIT. I became avidly interested in electromagnetics due to its impactful nature, and its wide range of validity. I spent 32 years of my life at U of Illinois and eventually became a distinguished professor at Purdue University.