Physics is second only to mathematics in the purity of its principles. Physics describes how the natural world works through applied mathematical formulas. It deals with the fundamental forces of the universe and how they interact with matter looking at everything from galaxies and planets to atoms and quarks and everything in between. All other natural sciences stem from physics. Chemistry is essentially applied physics and biology is essentially applied chemistry. Physics theory is responsible for the breakthroughs in electronics that precipitate advances in modern computers and electronic media.
One of the biggest discoveries that humankind has ever made is electricity. Through a proper understanding of physics, we have been able to harness it into something useful for electricity, which is just a large collection of electronics. By creating a voltage differential through something as simple as a battery, we can make electrons move, which is the entire basis of electricity. Moving electrons power the circuits that allow radios, televisions, lights and every other electronic device to work.
A transistor is the most basic part of a computer that has allowed for the creation of computer chips and has fueled the computer age. The transistor was developed through a breakthrough in solid state physics—the invention of the semiconductor. Semiconductors are simply pieces of elements that act differently under differerent temperatures and voltages. This means that upon different applications of voltage, a semiconductor can be made to hold information, which is stored because, until you apply a voltage to change it, a semiconductor outputs a high or low voltage. High voltages are interpreted as 1s and low voltages are interpreted as 0s. Through this simple system, all computers are able to store information in billions of little transistors.
The advance of the airplane is due primarily to advances in physics. Airplanes are capable of flight according to Bernoulli's fluid dynamics formulas. The amount of people that a plane can carry is proportional to the amount of thrust it can generate. This is true because the thrust pushes the wing forward and air curves over the wing and causes lift. The air that curves over the wing causes an area of low pressure, and the slower moving air underneath the wing pushes up on the bottom of it. The faster the wind, the more lift generated and the more weight the plane can carry.
Rocket science relies heavily on physics, deriving the formulas for thrust and combustion directly from it. The force of combustion is a measurable quantity, and the force can be directed through a nozzle to create a knowable thrust. With these knowable equations, we can calculate the thrust needed to achieve liftoff. The vacuum of space is overcome through an understanding of pressure. The low pressure outside the vessel has to be overcome through a seal of proper strength. We can use pressure calculations to figure the strength of the seal. In conclusion, space flight being one of the greatest achievements, the future of humankind was determined through an understanding of physics.
The nuclear bomb, one of the most powerful weapons humankind has at its disposal, is directly related to physics. An atomic bomb uses a process called fission to split apart heavy atoms. This process allows us to unlock the energy inherently present in matter. This understanding of matter also has the possibility of allowing us to produce untold amounts of energy we can harness for nonmilitary purpose. Additionally, fusion, or the combination of different atoms, could be the future solution to all our energy needs.