In one of the revolutionary scientific articles published by Albert Einstein in 1905, the formula E = mc was presented2, where "E" stands for energy, "m" for mass and "c" for the speed of light in vacuum. Since then E = mc2 has become one of the most famous equations in the world. Even those who have no knowledge of physics know this equation and are aware of its prodigious influence on the world we live in. However, most people miss its meaning. In simple terms, this equation describes the relationship between energy and matter, making us essentially deduce that energy and matter are interchangeable. This seemingly so simple equation has forever changed the way we look at energy, providing us with the basis for arriving at many of the advanced technologies we currently have.
Steps
Part 1 of 2: Understanding the Equation
Step 1. We define the variables present in the equation
The first step in understanding the meaning of any equation is to understand what each variable involved represents. In our case E represents energy, m the mass and c the speed of light.
The speed of light, c, is normally understood as a constant that assumes a value of 3, 00x108 meters per second. In the equation it is squared, based on the following main property of energy: to move at twice the speed of another, an object must use four times the energy. The speed of light is used as a constant because by transforming the mass of an object into pure energy, the latter would move at the speed of light.
Step 2. Understand what is meant by energy
There are many forms of energy in nature: thermal, electrical, chemical, nuclear and many others. Energy is transferred between systems, i.e. it is supplied by one system which in turn takes it from another. The unit of measurement of energy is the joule (J).
Energy cannot be created or destroyed, it can only be transformed. For example, coal has a significant amount of energy that it releases in the form of heat when it is burned
Step 3. We define the meaning of mass
Mass is generally defined as the amount of matter contained in an object.
- There are also other definitions of mass, such as "invariant mass" and "relativistic mass". The first is the mass which remains the same, no matter which frame of reference you use; relativistic mass, on the other hand, depends on the speed of the object. In the equation E = mc2, m refers to the invariant mass. This is very important, because this means mass Not it grows with speed, contrary to popular belief.
- It is important to understand that the mass and weight of an object are two different physical quantities. The weight is given by the force of gravity that is exerted on the object, while the mass is the quantity of matter present in the object. The mass can only be changed by physically altering the object, while the weight varies as the force of gravity exerted on the object varies. Mass is measured in kilograms (kg) while weight is measured in newtons (N).
- As in the case of energy, mass cannot be created or destroyed, only transformed. For example, an ice cube can melt and become liquid, but the mass will always remain the same.
Step 4. Fully understand that energy and mass are equivalent
The equation in question clearly states that mass and energy represent the same thing, and is also capable of providing us with the exact amount of energy contained within a given mass. Basically, Einstein's formula indicates that a small amount of mass contains a large amount of energy within it.
Part 2 of 2: Applications of the Equation in the Real World
Step 1. Understand where the energy we use every day comes from
Most forms of energy consumed in the real world come from the burning of coal and natural gas. These substances, by burning, take advantage of their valence electrons (these are the electrons located in the outermost layer of an atom) and the bond they have with other elements. When heat is added, this bond is broken and the energy released is what is used to power our society.
The method by which this type of energy is obtained is not efficient and, as we all know, it costs a lot in terms of environmental impact
Step 2. We apply Einstein's most famous equation to obtain energy much more efficiently
The formula E = mc2 shows that the amount of energy contained in an atom's nucleus is much greater than that contained in its valence electrons. The amount of energy released by splitting an atom into smaller parts is far greater than that obtained by breaking the bonds that hold its electrons
The energy system based on this principle is the nuclear one. In a nuclear reactor, the nucleus fission (i.e. fragmentation into smaller parts) is caused and then the enormous amount of energy released is stored
Step 3. Let's discover the technologies made possible by the formula E = mc2.
The discovery of the equation E = mc2 made it possible to create new technologies, many of which are the basis of our life today:
- PET: Medical technology that uses radioactivity to scan the human body internally.
- The formula of relativity made it possible to develop satellite telecommunications and vehicles for space exploration.
- Radiocarbon dating determines the age of an ancient object by exploiting radioactive decay based on Einstein's equation.
- Nuclear energy is an efficient form of energy used to power our society.
