Top 10 Physics Highlights of the Year

2024 was a year of great research into many topics in physics. Two scientists were awarded the Nobel Prize in Physics for their work in artificial intelligence for the very first time. End-of-year roundups from New Scientist, Physics World, BBC Science Focus, Science News, Discover, How It Works, and Scientific American included significant discoveries of the year. his list brings together 10 of the most-talked-about research works. The ranking of the list is not in order of priority or importance; numbering has been done for ease only.

1. Nobel Prize in Physics for Research on Artificial Intelligence

This year's Nobel Prize in Physics was awarded to American scientist John J. Hopfield and Canadian scientist Geoffrey E. Hinton for their groundbreaking discoveries and innovations that paved the way for the creation of machine learning through artificial neural networks. Their work dates to the 1960s.

John Hopfield theorized artificial neural networks that would mimic the neuronal connections within the human brain by using computational techniques. His "Hopfield Network" used basic concepts in physics, particularly the atomic spin properties of matter. These atomic spins enable each atom to behave like a small magnet. This is the basis for teaching artificial intelligence systems or machines.

Later, Geoffrey E. Hinton, a professor at the University of Toronto, extended the Hopfield Network to create a new network called the "Boltzmann Machine." Although it is based on the basics of the Hopfield Network, its operating procedure differs considerably. Hinton utilized ideas in statistical physics to develop this network.

The awarding of the Nobel Prize in Physics for AI research was a bit controversial, but it gained large attention within the scientific community. The contribution of technology, especially artificial intelligence, to scientific research is expected to have even greater impact in the future.

2. Discovery of the New Subatomic Particle "Glueball"

At the midpoint of the year, a group of physicists discovered empirical support for the existence of the subatomic particle referred to as the "glueball." Through the examination of particle collisions within particle accelerators, they accumulated evidence indicative of the glueball.

Glueballs are supposed to emerge from a theoretical interaction involving gluons, the carriers of the strong nuclear force. Up until this study, there was no means to affirm the existence of glueballs. Gluons can interact with both quarks and other gluons. Researchers theorized that gluons might collide with each other, creating a new particle, now referred to as the glueball.

While glueballs have not yet been included in the Standard Model of particle physics, this research has finally allowed scientists to make a move towards considering the potential existence of these particles. This discovery is one of the most important for the field of particle physics this year.

3. Interaction Between Photons and Matter

Photons, the particles that make up light, enable us to see the world. But when these photons interact with matter at an atomic scale, the exact mechanisms involved have been shrouded in mystery despite much interest from physicists like those at the University of Birmingham, UK. Later this year, an academic paper on the subject was circulated. The team proposed a new theoretical approach to understand photon-matter interactions while simultaneously using computational models to discern geometric properties of photons.

This discovery is of significant importance for several reasons. It can bring about advancement in secure communication technologies in the information technology field, improve disease diagnosis methods, and enable the control of chemical reactions at a molecular level. By understanding how photons interact with matter, scientists hope to design components for quantum computing and better solar energy systems.

4. Communication and High-Resolution Imaging with Entangled Photons

Scientists have discovered a method for sending pictures using entangled photon pairs. A team at Sorbonne University in France has used quantum entanglement to encode pictures into beams of light. Because the photons are entangled, the process is extremely secure—pictures are only visible to cameras that detect single photons and are invisible to all others.

This method also clears the path for making cameras that would do well under high-illumination conditions. It opens up possibilities for photographing images of biological tissues and enhancing long-distance communication.

In an investigation of related interest, researchers at the University of Glasgow in the United Kingdom have utilized entangled photons to increase the effectiveness of adaptive optical imaging techniques. Their solution significantly increases image resolution when compared to conventional bright-field microscopy. This breakthrough is foreseen as crucial in the development of quantum microscopes.

5. Semiconductors and New Switches Made from Carbon

Earlier in the year, there was a lot of talk about the possibility of making switches or logic gates—transistors used for logical operations in computers—out of graphene—single layers of carbon atoms. Marcelo Lozada-Hidalgo and his team at the University of Manchester, USA, have now done just that by exploiting the fact that graphene can carry both protons and electrons. The researchers created a device that can execute logical operations via the movement of protons, simultaneously encoding memory bits through the flow of electrons. Historically, these operations have been carried out by distinct circuits, leading to greater energy and temporal expenditures during data transmission. This advancement holds the promise of transforming the computing sector, contingent upon its commercial implementation.

In the middle of the year, there was a new use for graphene. Scientists from Tianjin University and the Georgia Institute of Technology in the US developed a material called "epigraphene." Unlike graphene, epigraphene has a bandgap similar to that of silicon, allowing it to act as a semiconductor. It can also withstand high temperatures above those withstood by silicon, making it a significant addition to the field of semiconductors. The discovery is seen as a major step in the development of electronic devices reliant on semiconductor technology.

6. Transparent Biological Tissue

Scientists at Stanford University in America have found a way to temporarily turn living mouse skin transparent. Biological tissues usually reflect light, which makes it hard to take clear pictures. This new study found that the molecular structure of yellow food dye, tartrazine, absorbs near-ultraviolet and blue light exceptionally well. Scientists used this dye to make biological tissues transparent.

The researchers applied the dye to various parts of the mouse, such as the abdomen and scalp, allowing the internal organs, including the liver, small intestine, and bladder, to be visualized without surgical intervention or high levels of radiation exposure. Once the dye was removed, transparency was lost. Although this methodology has been tested so far only in mice, scientists remain hopeful that it will develop novel ways of diagnosing human diseases.

7. Detection of Single-Nucleus Decay

Physicists at Yale University in the USA have been able to measure nuclear decay rate of a single helium nucleus this year. They have done this by embedding radioactive lead-212 atoms in silica spheres about one micron across. Then they measured the tiny reactions inside the sphere when a nucleus decays and calculated the decay rate of helium nuclei.

Their method can measure forces as small as 10–20 newtons and accelerations as tiny as 10–7 times gravitational acceleration. Researchers imagine that the technique could become sensitive enough to uncover neutrinos one day.

8. Cooling Positronium

Physicists from the CERN AEgIS Collaboration and the University of Tokyo this year, led by Kosuke Yoshioka, have taken independent approaches to cool positronium. Positronium is an atomic-like structure made of an electron and a positron, used mostly in laboratory experiments on antimatter. Currently, most experiments with positronium are done in a hot environment, which makes spectroscopic measurements difficult.

By cooling positronium to lower temperatures, scientists have opened up new avenues to examine the properties of antimatter with unprecedented precision. That results in the ability to make 10 to 100 times more antihydrogen than with previous techniques. Physicists are hugely interested in antihydrogen, which consists of a positron and an antiproton. Further study in this direction could eventually reveal more details on quantum electrodynamics and antimatter properties.

9. Describing the Structure of the Nucleus

For the first time, an international team of researchers has united two different ways of understanding an atomic nucleus. Underlying the laws of particle physics, an atomic nucleus is composed of quarks and gluons. Nuclear physics, however, has traditionally described the nucleus as a gathering of protons and neutrons that interact with each other.

The research team developed a new theory for nucleon pairs, that is, protons or neutrons, which are tightly bound to each other, forming strong interactions only lasting a few femtoseconds (10⁻¹⁵ seconds).

The accuracy of their model was tested by scattering experiments conducted on 19 different nuclei, ranging from helium-3 to lead-208. Experts consider this study as a big development in the understanding of nuclear structure and strong interactions.

10. Enhanced Titanium-Sapphire Laser

Sapphire, which is basically aluminum oxide, is combined with titanium to produce titanium-sapphire lasers. These lasers produce light in the red and near-infrared spectrum, a range of 650 nanometers to 1100 nanometers, and are widely used in scientific research. The conventional set-ups use high-powered laser light and produce specific wavelengths through the sapphire laser, costs of which run into more than $100,000.

A team of researchers at Stanford University has created a titanium-sapphire laser using a green laser diode costing only 37 dollars, compared with the traditional high-power laser light. The new approach would not only significantly reduce costs but also contribute to energy efficiency. The breakthrough makes critical laser technology more accessible both to scientific research and for industrial applications.