It is common that we just take for granted the existence of certain daily use tools or artifacts, without considering that their solely existence is based on quantum physics effects.
Many times I have heard how investment used in scientific research is questioned, especially considering that there are more pressing problems such as poverty or health; These discussions are based heavily on the premise that the investment made in such investigations is not productive and therefore it doesn’t make a difference to improve our society.
In my opinion, this is simply a problem of vision, confusion and unawareness about these facts, especially considering that history indicates the opposite; showing how research in pure sciences such as Physics and Mathematics has been the key to being able to have the technological benefits that we enjoy on a daily basis; and how these have been a transforming force that has changed our way of life in practically all its aspects.
A branch of science that is rarely considered as part of everyday objects is quantum physics, this topic commonly presented as something purely theoretical, and related to stories of somewhat unknown science characters, or well-known by clichés (such as Schrödinger’s cat, a subject for another post). This scientific branch, which was developed in the early twentieth century, is so intrinsically combined with our daily life that it is undoubtedly the most successful branch of science so far. If you wonder where the aspects of quantum physics apply to everyday objects, we can review some examples.
The LASER (Light Amplification by Stimulated Emission of Radiation) is the most distinctive example of a device based on quantum effects. In this effect, discovered by Einstein and known as the “stimulated emission of Radiation.”
Light travels in waves (electromagnetic waves), and they are distinguished by their wavelength. Red light for example, has a wavelength that’s longer than blue light. The light that we see from a lamp or from the Sun, contains light of several wavelengths, and such waves travels without order or “phase”, that is, the crests and valleys of these waves do not coincide, in the end the light we perceive is white light, a combination of all these waves.
In Lasers, a medium is used that is subjected to a stimulated radiation using for this purpose a medium such as ruby or gases such as rubidium. This light causes electrons in their atoms to be stimulated or “energized,” moving those electrons from a low-energy state (or from a low energy atomic orbital), to one of high-energy. This state is maintained briefly, and upon returning to its usual state of low energy, it does so by emitting a photon or a quantum package of electromagnetic energy; This “jump” is the quantum effect, and the emitted photons have the property of having the same frequency (distinctive of the medium), and the same phase. Therefore, the beam travels in only one direction and is of a specific frequency (or color).
It is difficult to consider that Einstein could have guessed how the laser will be used for cases such as bar code scanner devices or for audio or video players (such as CD or BluRay), Laser is used in a myriad of systems and services, from medicine to technology and science. all these working by the quantum effects of the stimulated light emission.
Today we take for granted the use of various electronic devices, from the simplest things like electronic keys in modern cars or USB data storage devices; to the indispensable smartphone, TV’s or portable computers. All of them function based on quantum effects that occur in solid state micro circuits such as those used in microprocessors or memory used in them.
These devices use transistors to operate, and in microelectronics, transistors etched on silicon substrate operate thanks to the tunnel effect, another quantum effect that allows a particle like the electron to cross an insulating physical barrier when reaching a certain level of energy. (from which derives the name of “semiconductor” since these materials partially conduct the electric current, given certain conditions).
This happens given the quantum property of duality of the electron (which can behave as as wave, as well as a particle), with this quantum effect, when gaining energy, the electron can cross this physical barrier; In a simple but not-so-precise analogy, it is as if the electron were a “ghost” particle and could cross this barrier, just as ghosts in some movies can cross walls, as long as the barrier reaches a certain level of energy.
Currently it is difficult to imagine any service or system where the use of microelectronics is not used (all based on quantum effects), this is the foundation with which information services and communications systems such as the Internet, operate.
The study derived from the invention of incandescent lamps, at the end of the nineteenth century, was what gave rise to quantum physics; this new branch of physics was discovered by Max Planck, who seeking an explanation of the phenomenon of why an incandescent material emits light. Until then, this effect was known, but the reason of why it happens wasn’t, or the explanation of why a material such as metal at a very high temperature has a reddish glow. Planck encountered difficulties and inconsistencies trying to explain this effect with classical physics, having to invent a new theory where the energy absorbed by a body is emitted as electromagnetic radiation, mostly at a specific frequency, but this radiation was not emitted as waves, but as small energy packages that he called “quanta”, and with this he created a revolution in science and the new branch of quantum physics.
Other lamp types are also based on quantum effects are fluorescent lamps, of commonly called Neon lamps (because of the gas some of them use), these works by vaporizing Mercury, and its atoms, when ionized by an electric current, cause their electrons to absorb energy and then release it as light, that for Mercury turns out to be ultraviolet light; all this based on a quantum effect. This ultraviolet light is then converted into visible light using a fluorescent coating these lamps have.
Finally, the most recent and commonly used lamps are based on LED’s, an acronym for Light Emitting Diode, LED’s also work on the same principle of semiconductors as those from transistors used in electronic equipment, but in its particular arrangement, the recombination of electrons in its atoms release energy in the form of photons, or particles of light, all of them of a single frequency. In addition to its advantages in terms of duration and lower energy consumption; having them for primary colors (Red, Blue and Green), these are now used to manufacture screens such those used in smartphones and flat screen TVs, as they can reproduce a wide range of colors.
Quantum physics is not only an interesting scientific description of certain effects, this is a fundamental part of science that has allowed us to obtain enormous technological benefits, effects that by the way, are also frequent in nature.
The mechanisms with which stars, like our sun, work, the our own brain functioning or how plants generate oxygen through photosynthesis are also cases that are possible by quantum effects. So it is not only artificially how these effects are applied, these are also intimately related to nature.
Regards Alex, ScienceKindle!