What is energy as we understand it

Dr Irengbam Mohendra Singh
Silas Weir Mitchell was one of the most prominent physicians in 19th and early 20th century America, famous for his research on phantom limbs. In his youth, however, his father wanted him to become a surgeon. There was one major problem. He had no energy ie capacity for performing surgery, often fainting at operations.
The ancient Egyptian civilisation depended on the ‘energy’ given by floods of the River Nile. The Indus civilisaton harnessed the energy of the Indus River. So did the Babylonian civilisation that exploited the water of the Rivers of Tigris and Euphrates.
One definition of energy is the “capacity of a physical system to perform work”. Energy is a word we use everyday all over the world, as some sort of an unseen power. Human energy for example, can be affected by changes in the levels of vitamins in the body. We know where our energy comes from. Starved of food, we lack energy. But what is energy?
While studying mechanics at high school, we have been taught about kinetic and potential energy, and physics at college, as “capacity for work”. But we were never told exactly what energy is. I became a graduate in physics, chemistry and biology, and later in medicine, without any clear idea of what energy is. At medical college, how energy is stored in the ATP (Adenosine Triphosphate) molecule and released when it’s converted to ADP (Adenosine Diphosphate) in cells, is a ‘must know’ for every student.
Music is moral energy for some. I find it manifest every night as I listen to old Hindi movie songs from my smart TV. It physically lifts me up to Heaven, with the module of ‘memories of my youth’, which is every bit as engaging as Byron’s swagger.
Orthodox Hindu Meiteis Like my father, used to release moral energy, also called human energy, and transfer it to listeners, by performing Nat Sankritan, which is ‘inscribed as UNESCO’s ‘intangible heritage’. Their ritual singing, drumming, crashing of small brass cymbals, and dancing, reflect the community’s Vaishnav culture, in which they narrate the lives and times of Krishna.
Energy, we know, can exist in many forms: potential, kinetic, chemical, thermal, electrical, nuclear or other forms. It takes energy to do absolutely anything, from steam-powered locomotives that pulled all trains in India to the latest nuclear-powered giant British aircraft carrier HMS Queen Elizabeth.
When we eat food we engage chemical energy stored in plants and animal flesh to power our muscles in the body to do mechanical work. When we feel hungry we are lacking energy. We get energy from glucose, converted from carbohydrate in our food. Plants also get energy from glucose produced by ‘photosynthesis’ with the energy of sunlight.
Some bacteria living deep at the bottom of the sea, get their energy from ‘chemosynthesis’ ie without sunlight, but energised by the chemical hydrogen sulphide, released by thermal vents (discovered in late 1970’s). The energy which keeps us going is released by chemical reactions in our body cells, in the form of heat energy that is produced by mitochondria inside the nuclei of cells (cf. Author’s The Origin of Meiteis[ …], p72). Corpses are cold because no energy is produced.
In the split seconds following the creation of our Universe with the Big Bang, 15 billion years ago, according to particle physicists, there was nothing but ‘energy’ (?). And they say, from that intense energy emerged hydrogen and then by their fusion, helium, followed by a few light elements. Eventually, stars like our Sun and galaxies were formed.
Since its birth, the Sun has been giving our Earth an enormous amount of energy by nuclear fusion of hydrogen, a tiny fraction of which was produced by the explosion of the first hydrogen bomb by the US on November 1 1952 at an atoll in the Pacific Ocean. This hydrogen bomb produced 450 times more energy than the combined bombs dropped over Nagasaki and Hiroshima, which were produced by nuclear fission.
Thermal energy released by the burning coal, was used to produce steam from water, to perform mechanical work by moving pistons that make the wheels of a train to turn. The physical energy of water in high speed as in the Loktak Project in Manipur, turns propeller-like turbines, which in turn, rotate metal shafts in electric generators to produce electric energy. Sound energy is converted to electrical energy by an object inside the telephone. It then travels along the wire to the receiving telephone where it’s reconverted to sound energy. All phone lines have a constant flow of electrical energy of about 2v.
Now we have an idea of what energy is, and that energy can be converted from one to the other and to the other. Mass and energy are basically the same and energy cannot be created or destroyed. But what is this energy? It still baffles me. It doesn’t allow me to bootstrap my way through kinetic or potential energy.
Modern technology has now enabled scientists to measure energy. Even emotions like anger, which is energy, can now be measured by fMRI (functional magnetic resonance imaging) scan, by computing the increase in the uptake of oxygen at emotion-specific areas of the brain. PET (positron emission topography) can locate ‘emotion specificity’ activation in specific brain regions by assessing metabolic activity through injection of radioactive isotope, the concentration of which can be measured.
As I walk along the isles in food supermarkets with my wife, I notice that pre-packaged food has a legal requirement to have a label printed with its ingredients and calorie/energy value as kca (kilocalories) or kJ (kilojoules) per 100g. It’s mainly because of the growing trend in obesity particularly in the young.
An average British diet contains is 2000 kcal (8368 KJ) per person. Andy Murray, the British two-time Wimbledon tennis champion is known to eat 6,000 calories during tournaments, to cope with his performance. Our body is like a car. When you depress the accelerator, the engine will open the throttle and introducing more fuel to explode. The bigger the explosion the greater is the energy, which then will move the pistons and turn the wheels faster.
A Joule of energy is equal to the force used to move a specific object one metre in the same direction as the force. Energy can be calculated using Einstein’s equation, E = mc2 (emc2). ‘E’ is energy in Joules; ‘m’ is mass in kilograms; and ‘c’ is the speed of light in metres per second, and “squared”.
The complicated process of photosynthesis in which energy is transferred from one form to the other, unknown in my student days, shows mindboggling chemical reactions. It involves a series of electron transfers. Plants take in carbon dioxide, produced by all breathing organisms, and reintroduce oxygen into the atmosphere, for them to breathe. They chemically mix carbon dioxide with water, using the Sun’s energy, which the green pigments of chlorophyll capture. Chlorophyll is a large molecule, containing many elements. It’s capable of converting the energy of sunlight into chemical energy by transforming carbon dioxide and water into carbohydrate in its simplest form as glucose, while releasing O2. During the process the chlorophyll molecule combines with oxygen and loses electrons, which can move to an appropriate recipient (vide infra). Photosynthesis thus creates energy that makes glucose, cellulose and starch for plants , algae, and certain bacteria known as cyanobacteria.
Botanists have now discovered another type of photosynthesis without oxygen (vide supra), known as ‘anoxygenic photosynthesis’, using electron donors other than water, usually a molecular hydrogen in the bacterial environment. The process uses light-energy (photons) to synthesise ATP by chemosmosis. All known organisms that carry out anoxygenic photosynthesis are known as anaerobes.
In anoxygenic photosynthesis, according to David Braun, professor of Botany at the University of Wisconsin-Madison, the process in which electron donors other than water are used, typically occurs in bacteria, such as purple bacteria and green sulfur bacteria. The process does not produce O2. What is produced depends on the electron donor eg many bacteria that use foul-smelling hydrogen sulfide, produce sulfur as a byproduct.
We get energy from glucose, which is converted from sugar in the intestinal wall by an enzyme after a meal containing carbohydrate. Glucose is absorbed within 15 minutes and will dissolve in the circulatory blood stream and thence, diffuse into body cells where they combine with oxygen we breathe in, to release energy. Protein and fat are not usually converted to glucose except in emergency. Body reserves them for vital functions.
As glucose is absorbed quickly, athletes like Wimbledon Tennis players eat or drink glucose- containing stuff to provide instant energy. Bananas also provide a quick-fix energy with potassium that prevents muscle fatigue.
All the energy we use for our sustenance comes mostly from ‘fossil fuels’ ie wood buried under rocks for ages and cooked by Earth’s internal heat to make coal, oil or gas. The energy originally came from the Sun, captured through photosynthesis. As they are now depleted, scientists are working to find ‘renewable’ energy, such as solar, wind, wave, biomass, hydropower and geothermal energy, as well as nuclear energy.
In conclusion, energy for me, is still an elusive driving force. The word energy is relatively young. It was first coined by a physician Thomas Young in 1807.
(The writer is based in the UK. Email:[email protected] Website:www.drimsingh.co.uk)

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