Like any branch of science, physics is inherently interesting because it helps to explain so much about the natural world around us. It satisfies basic curiosities about the workings of our world, and it reveals order in a universe that otherwise can appear pretty random and chaotic. There is a certain beauty in this order, similar to a classical symphony or a fine painting of a landscape. However, physics brings a lot more to the table than just its aesthetic appeal. Physics also provides the basis for a lot of incredibly useful technology, as we will see.
Any attempt to understand the natural world begins first and foremost with observation. After all, we have to know what it is we’re trying to explain before we go about explaining it. Observations can be mundane (e.g., dropped objects always go down) or subtle (e.g., the high tide is a little higher when the moon is full). Generally speaking, observations are qualitative in nature; that is, they help us to determine traits, characteristics, or qualities of some aspect of nature.
A souped-up form of observation is measurement. Measurements go one step further and provide quantitative information; that is, they assign a value of some sort to what we have observed. For example, we can merely observe that the sun rises and sets, but we can also measure when exactly that happens. Time, temperature, mass, and size are all common quantities that are measured. As we will see over and over again, measurement is vital to the development, validation, and application of new laws of physics.
DEFINITION
A qualitative observation provides information about the distinguishing attributes, properties, or characteristics of an object or phenomenon.
A quantitative measurement provides information about the size or magnitude of the characteristic under study, and assigns a numeric value in terms of some basic unit.
Physicists, and scientists more generally, make use of observation and measurement to begin the process of understanding the natural world. They try to attach their observations to a logical framework based on a set of self-consistent physical laws, usually in the form of mathematical models. Once uncovered, these laws of physics can be used to explain a wide range of phenomenon, from the interactions between tiny particles to the explosions of enormous stars. Moreover, we will see throughout that the quest of physicists is not merely to discover more and more physical laws, but to unify and reduce these to the smallest and simplest set of laws possible.
While a clear and coherent understanding of the natural world is a worthy goal in and of itself, it is really just the starting point of something much more powerful. The laws of physics offer the additional utility of predicting and controlling the future of physical and chemical systems. We can say with near certainty that tomorrow morning the sun will not only rise, but will do so in the east at such-and-such time. This is because the mathematical framework that governs the rotation of Earth and its revolution about the sun says so. Few physicists are clairvoyant, though most have probably predicted the future in one way or another.
Finally, if observation, understanding, and prediction weren’t enough, physics serves as the basis for countless technologies. Once we have uncovered the laws of physics, we can apply them to do useful things. If cut at just the right length, a swinging pendulum helps us keep track of time. If arranged in just the right manner, a system of wires will light our homes. If refined in just the right way, ores dug from Earth can produce vast amounts of heat and unimaginably strong explosions.
The control of physical phenomena can be used to improve the quality of our lives. But to develop new technologies, we need to understand the underlying physical laws. To discover physical laws, we rely on measurement and observation. But how do physicists go about turning observations and measurements into the laws of physics in the first place? Clearly, before we go much further we need to explain what physicists actually do when they go to work. By this we don’t just mean taking measurements or solving equations or writing computer codes, we are referring to the process of physics as a whole.
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