From the birth of quantum mechanics to the cutting edge of nanoscience and the deepest reaches of fundamental physics, this article explores how our understanding of the universe has evolved—from the scale of everyday experience down to the Planck length
It all started at the end of the 19th century and the beginning of the 20th century. Max Planck came up with his description of black-body radiation and the introduction of quanta—packets of energy. J.J. Thomson discovered the first elementary particle, the electron. Albert Einstein had his memorable year, 1905, in which he furnished indirect proof of the existence of atoms in his paper on Brownian motion. With the photoelectric effect explained and wave–particle duality introduced, he cemented his status as ‘a man apart’, and continued to do so even after his Nobel Prize for this in 1921.
This marked the start of an intense quest for a description of the infinitesimal. Ernest Rutherford attempted to unravel the atomic model, but it was Niels Bohr and his followers who perfected the theory. Quantum mechanics was born. Niels Bohr described the atom as consisting of a positively charged atomic nucleus with negatively charged electrons orbiting around it, like a minuscule solar system. Wolfgang Pauli’s exclusion principle assigned the electrons to well-defined orbitals or energy states around the nucleus. Werner Heisenberg’s matrix mechanics and Erwin Schrodinger’s famous equation described a model for the movement of electrons around the nucleus as a probability function. Heisenberg introduced his uncertainty principle, and Louis de Broglie demonstrated that if an electromagnetic wave can have a particle nature, each particle or object can also have a wave nature.
The world of the smallest appeared to be very strange and confusing. Here, not only concepts like wave–particle duality, but also entanglement, nonlocality, superposition, quantum tunnelling and nuclear spin resonance are regarded as perfectly normal. Nonrealism—in which a particle or object has no physical identity unless it is measured or observed—is the concept that a property has no value unless it is measured. The outcome depends on how it is measured. This all felt completely counterintuitive.
The Aristotelian worldview was more comprehensible, but the laws and equations of relativity theory and quantum mechanics led to very real applications. However incomprehensible, these theories give a much more accurate description of reality than the first, more intuitive concepts. Without a relative view of time, GPS would be impossible. Quantum mechanics has proven to be one of the most successful theories of physics, and today, around 30% of the global economy is based on it. The most bizarre aspect of quantum physics appears to be the significance of observation, perception, measurement, and interaction with the environment. The fact that the ‘conscious’ observer interacting with the environment experiences another, macroscopic reality other than the microscopic reality that lies behind it.
Energons and the universe
Aristotle’s worldview gave humanity an intelligible and static universe. Science has since discovered that the universe arose some 13.8 billion years ago. The general consensus is that this occurred in a ‘Big Bang’, in which everything suddenly emerged from nothing.
Some scientists, such as Erik Verlinde, have a problem with this. It is intuitively very difficult to imagine that everything can arise from nothing. Galileo Galilei reduced the role of intuition in science and argued for the criterion of experimental verification. Still, assumptions that are impossible to verify or falsify experimentally and contradict sound intuition must be properly challenged.
In his 1958 lecture ‘There is plenty of room at the bottom’, Richard Feynman laid the foundation for the development of nanotechnology, a term introduced by Eric Drexler in 1986.
Nanoscience and the microworld
In nanoscience, we learn that when material particles become smaller than a limit of around 100 nanometers, the surface area of the particle becomes more significant than its volume. This is in contrast to the situation in which the bigger an object—and in cosmological terms, a space—is, the bigger and more significant the volume becomes relative to the surface area. This is a crucial aspect of Erik Verlinde’s concept of gravity as an emergent entropic force in an elastic universe.
Returning to the microworld, we find that material particles of 100 nanometers or less begin to exhibit unusual properties. When the surface area becomes more significant than the volume, even familiar macroscopic properties appear to change. Gold nanoparticles have a different colour and melting point. When they interact with the right wavelength of electromagnetic radiation, they are capable of plasmon resonance. A familiar substance, such as gold, appears to exhibit completely different physical behaviour and obey different physical laws when it is split into dimensions where the surface area dominates over the volume.
Moreover, 100 nanometres in the microworld is still enormous. The diameter of atoms ranges between 0.6 and 6 angstroms, or 0.06 and 0.6 nanometres. Quantum dots—nanoparticles consisting of a number of semiconductor atoms and whose size is comparable to or smaller than the width of the wave function of an electron—enter a state where quantum effects predominate. They then behave like a single molecule, and their energy bands shift accordingly. This is the effect of quantum confinement. They interact with electromagnetism, allowing them to radiate light of very specific wavelengths or, when they absorb it, to supply high-energy electrons capable of starting photochemical reactions.
Probing the fundamental particles
From 100 nanometres down to the dimensions that the LHC, CERN’s Large Hadron Collider, can currently penetrate is another order of magnitude. This allows scientists to observe the interactions of elementary particles on a scale and to study the carriers of fundamental natural forces.
With the most advanced measuring equipment available today, the LIGO (Laser Interferometer Gravitational-Wave Observatory), it is possible to detect a change of less than the diameter of an atomic nucleus at a distance of 4 km. This has allowed the gravitational waves predicted by Einstein to be detected. The changes measured are on the improbable order of 1 attometre: 10-18 m.
From attometres to planck lengths
An attometre is an almost incomprehensible distance. It is far removed from 100 nanometres, the distance at which surface area begins to predominate over volume. If we then note that the distance between 1 m and 1 attometre is, relatively speaking, about the same as the distance between 1 attometre and 1 Planck length, we may be entering a completely different reality. Most physicists consider a Planck length, lp ≈1.616199 10-35 m, to be the smallest possible distance, because it is the limit to which Heisenberg’s uncertainty principle applies. At such small distances, we can assert that volume becomes insignificant or even disappears completely, leaving only a one-dimensional surface.
Calculations of how much information empty space contains show that precisely a single bit, a qubit or quantum bit, fits into such a Planck area or Planck surface. This has led some scientists to suggest that information is a fundamental building block of the universe.
Using their theory of the ‘holographic principle’, Gerard’t Hooft, Leonard Susskind, and later, Juan Maldacena have demonstrated the law of ‘conservation of information’. That is why Erik Verlinde has trouble with the concept of the Big Bang, in which all information suddenly appears from nothing. According to him, the information from the very beginning of the universe can’t be equivalent to the rich collection of information found in the cosmos today.
Information as a fundamental entity
We can imagine a more fundamental entity than the universe. An ‘information entity’, that consists only of qubits—of information, of energons as one-dimensional Planck surfaces, out of which information can bubble up like vapour bubbles in boiling water, comprising all the information for the birth, evolution and end of a universe. This would then result in the system reverting to its state of maximum entropy—returning to its pure information state.
Sci 2021, 3,35. https://doi.org/10.3390/sci3040035
