Circa 2019 o.o
In analogy to the coupling of atoms into molecules, the authors fuse colloidal semiconductor nanocrystals into quantum dot dimers. These nanocrystal ‘molecules’ exhibit significant quantum coupling effects, making them promising for applications in devices and potential quantum technologies.
The story of particle mass starts right after the big bang. During the very first moments of the universe, almost all particles were massless, traveling at the speed of light in a very hot “primordial soup.” At some point during this period, the Higgs field turned on, permeating the universe and giving mass to the elementary particles.
The Higgs field changed the environment when it was turned on, altering the way that particles behave. Some of the most common metaphors compare the Higgs field to a vat of molasses or thick syrup, which slows some particles as they travel through.
Others have envisioned the Higgs field as a crowd at a party or a horde of paparazzi. As famous scientists or A-list celebrities pass through, people surround them, slowing them down, but less-known faces travel through the crowds unnoticed. In these cases, popularity is synonymous with mass—the more popular you are, the more you will interact with the crowd, and the more “massive” you will be.
It looks like the LHC may have found a surprise massive particle that gives a glimpse into a better – and entirely unexpected – theory of reality.
Circa 2000 o.o 100000 times hotter than the sun quark gluon plasma is.quite interesting.
The European Laboratory for Particle Physics (CERN) plans to announce today (10 February) that it has “compelling evidence” that its scientists have created the quark–gluon state of matter predicted to have existed shortly after the Big Bang.
If confirmed, this would be the first time that conditions within the first three minutes after the Big Bang — the point at which the protons and neutrons that make up atomic nuclei came into being — have been observed under experimental conditions.
Continue reading “CERN claims first experimental creation of quark–gluon plasma” »
The very first moments of the Universe can be reconstructed mathematically even though they cannot be observed directly. Physicists from the Universities of Göttingen and Auckland (New Zealand) have greatly improved the ability of complex computer simulations to describe this early epoch. They discovered that a complex network of structures can form in the first trillionth of a second after the Big Bang. The behavior of these objects mimics the distribution of galaxies in today’s Universe. In contrast to today, however, these primordial structures are microscopically small. Typical clumps have masses of only a few grams and fit into volumes much smaller than present-day elementary particles. The results of the study have been published in the journal Physical Review D.
A force is something which tends to change the state of rest or state of motion, or size, shape, the direction of motion of a body, etc… There are four fundamental forces: gravitational, electromagnetic, strong nuclear and weak nuclear forces. These forces are responsible for all possible interactions that can take place in this universe, from planets orbiting a star to protons and neutrons confined in the nucleus of an atom. In classical physics, the assumption was that an imaginary field exists, through which a force can be transmitted. But with the advent of quantum mechanics, this idea was changed radically. A field exists, but that is a quantum field. The field vibrates gently, and these vibrations give rise to particles and their corresponding antiparticle partners, i.e., particles with opposite charge. But these particles can exist for a limited amount of time. What gives rise to forces then? Particles called bosons. Bosons, named after Indian physicist Satyendra Nath Bose, are particles, the exchange of which give rise to forces. Bosons, along with the fermions (which make up matter), are referred to as elementary particles [1].
In quantum mechanics, energy can be temporarily ‘borrowed’ from a particle. But, as per Heisenberg’s uncertainty principle, the greater the amount of energy you ‘borrow’, the sooner you must return it [2].
Continue reading “The Higgs Boson and the Creation of Forces and Mass” »
Physicists at the LHCb Collaboration at CERN have found particles not behaving the way they should according to the guiding theory of particle physics. Could it be evidence of a brand new physics?
Data from ESA’s Gaia star mapping satellite have revealed tantalizing evidence that the nearest star cluster to the Sun is being disrupted by the gravitational influence of a massive but unseen structure in our galaxy.
If true, this might provide evidence for a suspected population of ‘dark matter sub-halos’. These invisible clouds of particles are thought to be relics from the formation of the Milky Way, and are now spread across the galaxy, making up an invisible substructure that exerts a noticeable gravitational influence on anything that drifts too close.
Continue reading “Tantalizing Evidence: Is the Nearest Star Cluster to the Sun Being Destroyed?” »
Artificial microswimmers that can replicate the complex behavior of active matter are often designed to mimic the self-propulsion of microscopic living organisms. However, compared with their living counterparts, artificial microswimmers have a limited ability to adapt to environmental signals or to retain a physical memory to yield optimized emergent behavior. Different from macroscopic living systems and robots, both microscopic living organisms and artificial microswimmers are subject to Brownian motion, which randomizes their position and propulsion direction. Here, we combine real-world artificial active particles with machine learning algorithms to explore their adaptive behavior in a noisy environment with reinforcement learning. We use a real-time control of self-thermophoretic active particles to demonstrate the solution of a simple standard navigation problem under the inevitable influence of Brownian motion at these length scales. We show that, with external control, collective learning is possible. Concerning the learning under noise, we find that noise decreases the learning speed, modifies the optimal behavior, and also increases the strength of the decisions made. As a consequence of time delay in the feedback loop controlling the particles, an optimum velocity, reminiscent of optimal run-and-tumble times of bacteria, is found for the system, which is conjectured to be a universal property of systems exhibiting delayed response in a noisy environment.
Living organisms adapt their behavior according to their environment to achieve a particular goal. Information about the state of the environment is sensed, processed, and encoded in biochemical processes in the organism to provide appropriate actions or properties. These learning or adaptive processes occur within the lifetime of a generation, over multiple generations, or over evolutionarily relevant time scales. They lead to specific behaviors of individuals and collectives. Swarms of fish or flocks of birds have developed collective strategies adapted to the existence of predators (1), and collective hunting may represent a more efficient foraging tactic (2). Birds learn how to use convective air flows (3). Sperm have evolved complex swimming patterns to explore chemical gradients in chemotaxis (4), and bacteria express specific shapes to follow gravity (5).
Inspired by these optimization processes, learning strategies that reduce the complexity of the physical and chemical processes in living matter to a mathematical procedure have been developed. Many of these learning strategies have been implemented into robotic systems (7–9). One particular framework is reinforcement learning (RL), in which an agent gains experience by interacting with its environment (10). The value of this experience relates to rewards (or penalties) connected to the states that the agent can occupy. The learning process then maximizes the cumulative reward for a chain of actions to obtain the so-called policy. This policy advises the agent which action to take. Recent computational studies, for example, reveal that RL can provide optimal strategies for the navigation of active particles through flows (11–13), the swarming of robots (14–16), the soaring of birds , or the development of collective motion (17).
Physicists from the LHCb Collaboration at CERN’s Large Hadron Collider (LHC) have observed four new exotic particles: Zcs (4000)+, Zcs (4220)+, X(4685), and X(4630). The new results provide grist for the mill of theorists seeking to explain the nature of tetraquark binding mechanisms.
“Hadrons discovered in the 1950-60s, the pioneering years in particle physics history, were called elementary particles till their structure was finally understood in the framework of quark model,” the LHCb physicists said.
