Physics is Essential

The status of physics is the subject of great concern. More students are going on to university than ever before and yet many universities in the UK are struggling to keep their physics departments going. Should we worry about this? Why is physics important?
On a personal level, physics is important if you would like to have an interesting career. A wide variety of companies employ physics graduates because they have very good analytical and problem solving skills. If you enjoy solving puzzles and understanding how things work, then physics is a fascinating subject that will enrich your life and advance your career. At a more fundamental level, studying physics is important because it seeks to understand the world at its most basic level. It is satisfying to know why the world is how it is. Even the most mundane objects have hidden in them a multitude of physics. As I write this article, I have on my table a glass of cherry-aide which absorbs most of the incident white light except for the red part of the spectrum which is why I see it is red in colour. The glass is stationary which mean the forces acting on it are in equilibrium. There is a downward force from the glass on the table and an equal and Gate Valve opposite force from the table pushing on the glass. We can look at the growth of bubbles of carbon dioxide in the liquid and how they form on the aspirates of the glass or on a particle of dust. The cohesvie forces of the molecules at the surface create surface tension. There is also the adhesive force of liquid to the glass which are greater than the surface tension, causing the liquid to rise at the edge of the glass forming a meniscus. If I move the glass sharply, the surface of the liquid oscillates with a well defined period. The viscosity of the fluid damps the oscillations. Light passing through the glass is refracted and the produces a image which is horizontally reflected and there are many more.
The principles of physics applied with engineering creates the technology which we all use without thinking. All the machines that we use in life depend work using physics can be analysed using physics to a certain extent. In fact it is difficult to explain how physics has changed our lives because the physics has been around for such a long time that we just don't think about it. However, there is one area of our lives that has been revolutionised due to our understanding of the so called modern physics.
At the beginning of the 20th century, it seemed that we pretty much knew all the physics required to describe everything. However, this was in fact far from the truth. As physicists explored the structure of matter, we found that instead of answering questions more questions were posed.
Our view of the structure of matter was a changed by the discovery of the electron by J. J. Thompson in 1897. At the time, Thompson remarked, "Could anything at first sight seem more impractical than a body which is so small that its mass is an insignificant fraction of the mass of an atom of hydrogen?" It was soon realised that electrical current results from the flow of electrons, it makes the electron just about the most practical sub-atomic particle ever discovered.
When physicists tried to applied the laws of physics that applied to objects much larger than electrons or atoms such as snooker balls or cars, they found that these rules no longer worked. For example there was a problem with the radiation emitted by hot objects known as blackbody radiation.
Blackbody radiation is the spectrum of light emitted by a perfectly absorbing object when it is heated. A good example of blackbody radiation would be the small amount of light emitted from the peephole of a hot furnace or oven (hence blackbody radiation is sometimes known as cavity radiation). As the temperature increases the interior changes colour. From a dull red, to cherry-red, orange, yellow and white as the temperature increases.
The amount of radiation emitted in a given frequency range should be proportional to the number of modes in that range. According to classical physics, all modes Freede Valve had an equal chance of being produced and the number of modes went up in proportion to the square of the frequency. However this predicted increase was not observed. It became known as the 'ultraviolet catastrophe'.
Planck suggested that blackbody radiation curves could be understood if intensity of the radiation from the walls of the oven were somehow constrained so that they could not continuously emit radiation but could only emit energy in discrete amounts called quanta. At higher frequencies, the radiation had to be emitted in bigger chunks. The lack of radiation in the oven at these higher frequencies was not seen because it would be very unlikely that one oscillating charge would by random excitation have an energy of, say, five times the average thermal energy. Even at high-frequencies, it would almost never have enough energy to emit one quantum, so by Planck's theory, it wouldn't emit any radiation at all. This idea lead was to lead to the development of quantum mechanics where particles have waves like properties, waves have particle like properties and we have to give up the certainty of the Newtonian clockwork universe and replace it with probability.
As if that were not bad enough, the very laws of motion were also under strain when applied to electromagnetic waves. Maxwell's equations related changes in magnetic fields that cause changes in electric fields and vice versa, in such a way that a solution for propagating electromagnetic waves could be set up. It is an amazing fact that the velocity of waves is given exactly by the ratio of two unrelated constants. This turned out to correspond to the speed of light, so that Maxwell identified 'light' to be an electromagnetic aether wave as well.
As the equations referred to light propagation with respect to the hypothesised aether, physicists tried to use this idea to measure the earth's velocity with respect to the aether. The most famous such attempt was the Michelson-Morley experiment. While these experiments were controversial for some time, a consensus emerged that the speed of light does not vary with the speed of the observer, and according to Maxwell's equations, it does not vary with the speed of the source, the speed of light must be the same (invariant) between reference systems.
It is this framework of ideas that lead Albert Einstein to formulate his theory of special relativity and later general theory of relativity which changed how we view the universe we live in. Instead of three dimensions of space, we were forced to accept that time is not an absolute property of the universe separate from space but that they are linked in a four-dimensional space-time. This leads to effect such as length contraction in the direction of motion and time dilation. These effects are very small for situations we encounter in our everyday lives but become significant at when velocities become close to the speed of light.
In 1905, Einstein published a paper on the photoelectric effect which changed the way we understood light. Light incident on the surface of a metal was able to eject electrons from the surface of a metal.
Ultra-violet light was able to eject electrons from the surface of a metal at almost any intensity. If light were a wave as experiments had shown, then the energy contained in the wave increased with its amplitude. Therefore, as the intensity of the light was reduced, fewer electrons should be ejected. If the intensity was so low then there would not be enough energy to eject an electron. But experiments showed that this didn't happen. For ultra-violet light, the number of electrons reduced but it was always possible for the light to eject an electron. But if red light were used, the light was not able to eject any electrons from the surface of the metal and it didn't matter how intense the light was.
Einstein realised that the energy was related to the frequency of the light and the energy was carried in discrete packets we call photons. The energy of a photon, E is related to its frequency, f, by E = hf where h is Planck's constant. The frequency of blue light is greater than that of red light and therefore it has more energy; the blue light has enough energy to knock the electrons from the metal atoms. Since increasing the intensity is just increasing the number of photons incident on the surface of the metal, red light, no matter how intense, will have enough energy to dislodge electrons from the surface. Einstein received the Nobel prize for this discovery in 1921.
Discoveries in physics are essential to create advances in technology. It is important to understand that these technologies could not be created by engineering alone; simply making an existing technology more efficient or smaller can lead to great progress, for example increasing the speed at which data can be sent down copper cables is increased but it is still essentially the same technology of the Victorian telegraph. Contrast that with fibre optics and laser communication which are direct descendants of the application of quantum physics in lasers.
The transistor, is of course, the basis of all electronic digital computers. Prior to their invention computers took up whole rooms because they where made using valves. Valves are large, fragile, expensive, generate a lot of heat and were unreliable. The transistor does the same job as a valve but relies on quantum physics in semiconductor materials. The difference in scale between a valve and the transistor allowed computers to become more powerful so that today (2007) a microprocessor has around, 200 million - 1.7 billion transistors. It is safe to say that the computing power we have today would not have been realised without the invention of the transistor and that would not have been possible without quantum physics.
It is difficult to put a price on the increased GDP (Gross Domestic Product) that discoveries like quantum mechanics and the electron produce.
It would be in the trillions of dollars. If you add on top the technology which directly stems from the understanding of the new physics: transistors, lasers, telecommunications, computers and the World Wide Web which are also at the root of trillions of pounds of GDP.
Developments in the future will be based on controlling the fragile stability of the quantum world. Quantum computers perform calculations on all the possible states of a system at once. Digital computers have bits which can exist in only two states, a 1 or 0. A quantum bit (qubit) is both 1 and 0 at the same time. When combined the with another qubits the computer is in all of the possible 2^the number of qubits states at the same time. The benefit is that calculations performed on all states at the same time, the final result is probabilistic, the answer being skewed to the correct answer. It is a bit like, 'Ask the Audience' option in who wants to be a millionaire. One hopes that the majority of the audience will have enough education to guess the correct answer and it is usually the most voted for. When the result is determined the correct answer is the most probable after the calculation has been repeated a number of times.
Of course, the aim physics in its purest sense is to discover the fundamental forces that make the universe what it is and from which every thing ultimately stems. The conditions that bought the universe into being cannot be studied directly but we can get close to the initial conditions of the universe by colliding sub-atomic particles at high energies. In collision of these particles, energy is transferred, particles are created and destroyed. The greater the energy, the closer we get to the conditions that existed a fraction of a second after the 'Big-Bang'. Whether one day physicists will eventually find all the laws of nature and become redundant is a matter for debate but as far as the technology the evolves from these discoveries is concerned we don't know where the next big discovery is going to come from and may be thought completely without application, like the discovery of the electron, or the laser. We can see that physics isn't important, it's essential.