By Chad Orzel, Union College
Albert Einstein is unquestionably the most iconic scientist in modern times. He pretty much sets the image most people have for what a physicist looks like: a white man with a mustache, wild white hair, a German accent, and an otherworldly air. His name conjures up images of some of the most brain-bending theories in the history of science. Read on to know more.
Einstein is best known for his theories of relativity, which transformed our understanding of space and time. Einstein also made key contributions to the theory of quantum mechanics, which tells us that light waves actually behave like particles, and material particles have some wave nature.
In his later years, he broke with the theory over philosophical difficulties relating to the randomness inherent in quantum theory and the ‘spooky’ interactions that seem to connect particles over long distances. He was wrong about some of these concerns, but even his mistaken ideas proved to be insightful and stimulated later breakthroughs.
Einstein’s Theories in Our Everyday Life
Together, the theory of quantum and the theory of relativity have utterly transformed our understanding of the universe and our place in it. They have also proven enormously important for modern technology, particularly quantum physics.
Without an understanding of the quantum nature of electrons, we wouldn’t be able to make the computer chips that are central to so many modern devices. Without an understanding of the quantum nature of light, we wouldn’t be able to make the lasers that carry the internet over a global network of fiber-optic cables. Without both quantum physics and relativity, we wouldn’t have the Global Positioning System to help us navigate through our daily lives.
Both quantum mechanics and relativity have been around for a hundred years, and are the subject of innumerable books, but popular treatments tend to emphasize the difficult and troubling aspects of these theories. This leaves many non-physicists with the impression that the science Einstein is known for is very far removed from our everyday reality.
Quantum Physics and a Toaster
However, physicists inhabit the same everyday world as everybody else, and they don’t just make theories up for no good reason. The modern theory of quantum mechanics exists because physicists were led to it by observations made right here, in the everyday reality we all deal with.
In fact, we probably see one of the key phenomena every morning, when we cook breakfast. Everything we know about quantum physics starts with the red glow of the heating elements in a toaster.
The glow of a hot object is a very simple and universal phenomenon. Take an object and heat it up, and it will glow red, then yellow, then white. The precise color depends only on the temperature. Physicists call this blackbody radiation, and it doesn’t matter what the object is made of or how you get it hot. No matter what you have, if you get it to the same temperature; it will glow in exactly the same way.
This is a transcript from the video series Einstein’s Legacy: Modern Physics All around You. Watch it now, on Wondrium.
Different Wavelengths of Light and Their Frequency
Physicists describe the color of objects in terms of their spectrum: the amount of light the object emits at every possible wavelength. What we call visible light falls in a particular band of wavelengths, from violet light at around 400 nanometers up to deep red light at around 700 nanometers.
But of course, there are many wavelengths that our eyes don’t register. As we move to wavelengths below 400 nm, we have ultraviolet light, then x-rays, and then gamma rays, and as we move to wavelengths longer than 700 nm, we have infrared, then microwave, and then radio waves.
Each wavelength has a corresponding frequency, which varies in the opposite direction: Short wavelengths have high frequencies; long wavelengths have low frequencies. The two are simply related—the wavelength multiplied by the frequency is always equal to the speed of light—so physicists tend to switch back and forth between wavelength and frequency, using whichever is most convenient for a particular problem.
The Blackbody Radiation
The spectrum of light from blackbody radiation is appealingly simple. We can represent this spectrum as a line on a graph showing the amount of light emitted at every possible wavelength for an object at a given temperature. As we start at long wavelength and low frequency and move to shorter wavelengths and higher frequencies, we see the amount of light emitted slowly increase, rising to a peak at a particular wavelength.
Then the amount of light being emitted drops very rapidly to zero. The position of the peak, the particular wavelength at which the object emits the most light, changes with temperature: The higher the temperature, the shorter the wavelength where the peak occurs. This explains the change in color: At low temperatures, the peak is off in the infrared, too long a wavelength for our eyes to see—at room temperature, the peak wavelength is around 10,000 nanometers.
As the temperature increases, the peak moves first into the red wavelengths, then yellow, and so on. At a temperature of a few thousand degrees Celsius, the peak spans the entire visible spectrum, so it appears white to us.
No matter what the temperature of the object is, the shape of the spectrum is always the same: on the long-wavelength side of the peak, a long tail, and on the short-wavelength side, a steep drop. As temperature increases, the total amount of light increases, and the peak moves to shorter wavelengths, but the shape is exactly the same.
Common Questions about Toasters and the Revolutionary Understanding of Quantum
Quantum theory is vital in our everyday life. For example, without quantum, it would not be possible to build computer chips that play a key role in many modern devices. Also, the technology of GPS would not have been possible without quantum physics.
Quantum theory has been around for a century, but attention only to its difficult aspects has led non-physicists to believe that quantum is far removed from everyday reality. However, contrary to popular belief, the modern theory of quantum exists because physicists were led to it by observations made in the everyday reality we all deal with.
Physicists’ observations are based on everyday reality. In fact, everything we know about quantum physics starts with the red glow of the heating elements in a toaster. The glow of a hot object is a very simple and universal phenomenon. Take an object and heat it up, and it will glow red, then yellow, then white. The precise color depends only on the temperature.