Quantum Physics: Curiosity and Perplexity

10-01-2024 | Posted by Joaquín Martí

Física cuántica

Christopher Nolan’s recent biopic has brought theoretical physicist Robert Oppenheimer into the limelight, popularly known as the leader of the Manhattan Project and the “father” of the atomic bomb. While this is what brought him fame, it is also true that he was passionate about physics and made valuable contributions in areas such as quantum physics and black holes.

Quantum physics is not a topic in which we at Principia consider ourselves experts, not even one whose foundations we master, although we use its findings. This post rather reflects our perplexity at physical concepts that we take advantage of, and most likely will take advantage of even more in the future, without our intuition really being able to familiarize itself with them.

Quantum physics studies the behaviour of subatomic particles, such as electrons and photons. Its formulation is not recent, as it has been on the table for over a century, with the work of Max Planck, Albert Einstein, Niels Bohr, and others. But it is so counterintuitive that it challenges our efforts to understand it in the light of macroscopic experience.

Física cuántica

Classical physics, developed by scientists like Isaac Newton, author of the Principia Mathematica that gives our company its name, was the dominant physics for many centuries. It describes the world in terms of mechanical laws and allows us to predict the movement of objects on human scales. But it ceases to be sufficient when studying objects on very small scales.

Quantum physics emerged in the early 20th century to address these limitations. One of the key ideas of quantum physics is that subatomic particles do not behave in the same way as objects on a human scale. For example, in quantum physics, a particle can be in two places at the same time, or it can be in a superposition of states, which means that its quantum state cannot be known until it is measured. And that several particles can be entangled and, by measuring the state of one of them, the state of the others is instantly fixed, even if they are light years away.

Another key concept of quantum physics is Heisenberg’s uncertainty principle, which states that it is impossible to simultaneously know with precision pairs of complementary variables, such as the position and momentum of a particle, or energy and time. The more is known about one of the two, the less is known about the other, and vice versa. And this is a fundamental limitation, not dependent on measurement technology.

Consequences of quantum physics, some with important practical implications, are:

– Tunnelling effect

– Zero-point energy

– Existence of virtual particles

– Vacuum energy and the non-existence of absolute vacuum

– Hawking radiation and the instability of black holes

Thus, quantum physics has allowed the construction of electronic devices such as transistors and computer chips. It has also led to the creation of new technologies such as lasers and magnetic resonance scanners. And advances in sensors, cryptography, computing, and information storage are promising.

But beyond specific applications, quantum physics has changed our understanding of the very nature of the universe. Quantum physics has shown that, at the level of subatomic particles, the universe is not a deterministic and predictable place, but is full of uncertainty and probabilities. And that is not easy to digest for engineers whose intuition is governed by purely macroscopic experience, even if they are capable of incorporating its results.

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