New research led by Northeastern University suggests that Alzheimer's disease may not progress like falling dominoes, as conventional wisdom holds, with one molecular event sparking the formation of plaques throughout the ...
Sep 16, 2016
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In a long-awaited finding, an international team of scientists using high-brightness x-rays from the U.S. Department of Energy Office of Science's Advanced Photon Source at Argonne National Laboratory has determined the high-resolution ...
Sep 27, 2013
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Cartilage is a fascinating substance. It coats the ends of our bones, allowing them to glide by one another at joints like our elbows and our knees. The surface it creates is about five times more slippery than ice on ice.
Mar 15, 2022
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With worldwide cardiovascular deaths at an all-time high, European scientists have developed a new handheld scanner that can read your heart's vital signs like a supermarket barcode reader can scan items at the checkout, ...
Jul 4, 2017
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(Medical Xpress)—When the brains of those who have succumbed to age-related neurodegeneration are analyzed post-mortem, they typically show significant atrophy on all scales. Not only is the cortex thinner and sparser, ...
Anesthetics have been used for patients undergoing medical procedures for about 175 years, but doctors and scientists have never known exactly how these drugs disrupt consciousness in the brain.
Aug 12, 2020
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Blood flow abnormalities found in the brains of veterans with Gulf War illness have persisted 20 years after the war, and in some cases have gotten worse, according to a new study published online in the journal Radiology.
Sep 13, 2011
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The pain and itching associated with shingles and herpes may be due to the virus causing a "short circuit" in the nerve cells that reach the skin, Princeton researchers have found.
Sep 10, 2013
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Our brains are made of billions of neurons, which are connected forming complex networks. They communicate between themselves by sending electrical signals, known as action potentials, and chemical signals, known as neurotransmitters, ...
Apr 6, 2023
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The brain is perhaps the most sensitive organ with respect to changes in blood flow and oxygen supply. Even brief interruptions in capillary flow (or "stalling") can indicate acute neurological issues; evidence suggests that ...
Sep 13, 2023
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In physics, a photon is an elementary particle, the quantum of the electromagnetic field and the basic "unit" of light and all other forms of electromagnetic radiation. It is also the force carrier for the electromagnetic force. The effects of this force are easily observable at both the microscopic and macroscopic level, because the photon has no rest mass; this allows for interactions at long distances. Like all elementary particles, photons are governed by quantum mechanics and will exhibit wave-particle duality – they exhibit properties of both waves and particles. For example, a single photon may be refracted by a lens or exhibit wave interference, but also act as a particle giving a definite result when its location is measured.
The modern concept of the photon was developed gradually by Albert Einstein to explain experimental observations that did not fit the classical wave model of light. In particular, the photon model accounted for the frequency dependence of light's energy, and explained the ability of matter and radiation to be in thermal equilibrium. It also accounted for anomalous observations, including the properties of black body radiation, that other physicists, most notably Max Planck, had sought to explain using semiclassical models, in which light is still described by Maxwell's equations, but the material objects that emit and absorb light are quantized. Although these semiclassical models contributed to the development of quantum mechanics, further experiments proved Einstein's hypothesis that light itself is quantized; the quanta of light are photons.
In the modern Standard Model of particle physics, photons are described as a necessary consequence of physical laws having a certain symmetry at every point in spacetime. The intrinsic properties of photons, such as charge, mass and spin, are determined by the properties of this gauge symmetry.
The photon concept has led to momentous advances in experimental and theoretical physics, such as lasers, Bose–Einstein condensation, quantum field theory, and the probabilistic interpretation of quantum mechanics. It has been applied to photochemistry, high-resolution microscopy, and measurements of molecular distances. Recently, photons have been studied as elements of quantum computers and for sophisticated applications in optical communication such as quantum cryptography.
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