Latest news with #light
The National
3 days ago
- Politics
- The National
IDF soldiers told to shoot at unarmed Gazans waiting for aid
Haaretz, Israel's longest running newspaper and its paper of record, reported that commanders had ordered troops to shoot at crowds to drive them away, even though it was clear they posed no threat. According to Gaza's Health Ministry, 549 people have been killed and more than 4000 wounded near aid centres and in areas where people were waiting for UN food trucks since May 27, when the Gaza Humanitarian Foundation (GHF) started operating. The GHF, which is a new aid organisation backed by Israel and the US, was tasked to take over aid operations in Gaza from humanitarian agencies. It has seen its distribution of aid marred by chaos. The distribution sites typically open for just one hour each morning. According to officers who served in their areas, the IDF fires at civilians who arrive before opening hours to prevent them from approaching, or again after the centres close, to disperse them. READ MORE: Labour rebels urged to 'stand firm' over welfare cuts despite Keir Starmer U-turn One soldier told Haaretz that the IDF's "form of communication is gunfire". He said: "We open fire early in the morning if someone tries to get in line from a few hundred metres away, and sometimes we just charge at them from close range. But there's no danger to the forces. "I'm not aware of a single instance of return fire. There's no enemy, no weapons." The soldier added that he has heard this being referred to by soldiers as "Operation Salted Fish", which refers to the Israeli version of the children's game "Red light, green light". An officer serving in the security detail of a distribution centre told the paper: "At night, we open fire to signal to the population that this is a combat zone and they mustn't come near. "Once, the mortars stopped firing, and we saw people start to approach. So we resumed fire to make it clear they weren't allowed to. In the end, one of the shells landed on a group of people." He also pointed towards other cases: "We fired machine guns from tanks and threw grenades. There was one incident where a group of civilians was hit while advancing under the cover of fog. It wasn't intentional, but these things happen." Another senior officer told the paper that the normalisation of killing civilians in Gaza has often encouraged firing at them near the distribution centres. He said: "The fact that live fire is directed at a civilian population – whether with artillery, tanks, snipers, or drones – goes against everything the army is supposed to stand for. "Why are people collecting food being killed just because they stepped out of line, or because some commander doesn't like that they're cutting in? "Why have we reached a point where a teenager is willing to risk his life just to pull a sack of rice off a truck? And that's who we're firing artillery at?" READ MORE: Four arrests after UK military planes damaged in Palestine Action RAF break-in An IDF spokesperson told Haaretz that troops were "conducting systematic learning processes to improve their operational response" and to minimise, "as much as possible, potential friction between the population and IDF forces". They said: "Recently, forces worked to reorganize the area by placing new fences, signage, opening additional routes, and more. "Following incidents where there were reports of harm to civilians arriving at distribution centres, in-depth investigations were conducted, and instructions were given to forces on the ground based on lessons learned." The number of fatalities near food distribution centres has risen sharply in recent weeks. According to Gaza's Health Ministry, 57 people were killed on June 11, 59 on June 17 and around 50 on June 24. The UN and other humanitarian agencies have refused to take part in the new system. Thameen Al-Keetan, the UN's human rights office spokesperson, said on Tuesday that "the weaponisation of food for civilians" constitutes a war crime. In the last 24 hours, Israeli forces killed at least 72 people in the Gaza Strip. Since October 7, 2023, a total of 56,331 Palestinians have been killed.
Yahoo
7 days ago
- Science
- Yahoo
Did light exist at the beginning of the universe?
When you buy through links on our articles, Future and its syndication partners may earn a commission. Nowadays, the dark of night is interspersed with the light of stars. But before the stars were born, did light shine at the beginning of the universe? The short answer is "no." But the long answer reveals light's extraordinary journey. At first, the early universe's light was "trapped," and it took several hundred thousand years for it to escape. Then, it took about 100 million years for stars to form. By examining the speed and direction in which galaxies were moving, astronomer Edwin Hubble discovered the universe was expanding. This 1929 discovery suggested that the cosmos was once smaller, with scientists eventually calculating that the entire universe was concentrated into one, infinitely dense point about 13.8 billion years ago, until the Big Bang happened. "With the Big Bang, space was created and expanded, along with everything in the universe," Andrew Layden, chair of physics and astronomy at Bowling Green State University in Ohio, told Live Science. The only way all the matter that now makes up the universe could fit in a tiny spot "is if it was energy at that time," Layden said. Einstein's famous equation E=mc2 revealed that energy and mass can be interchangeable, Layden explained. As the universe expanded, the density of its energy decreased, and it cooled. The first particles then began to form within the first second after the Big Bang, according to Las Cumbres Observatory. These included the photons that make up light, as well as the protons, neutrons and electrons that make up atoms. By about three minutes after the Big Bang, protons and neutrons could fuse together to create the nuclei of atoms such as helium, according to NASA. "Think of fog and dew," Layden said. "Particles in a high-energy state are dispersed like water in fog, and when the energy gets low enough, they can condense out like droplets of dew." Related: Can anything travel faster than the speed of light? However, although photons of light existed since the first second after the Big Bang, they could not yet shine across the universe. This is because the early cosmos was so hot that "electrons were moving too fast for atomic nuclei to hold them in orbit around them," Layden said. "The universe was just this very hot, dense soup." All the electrons zipping around freely in the early universe meant that light could not move around very much. "As light tried to travel in a straight line during this time, it always bumped into electrons, so it could not go very far," Layden said. A similar situation is found within the sun, Srinivasan Raghunathan, a cosmologist at the University of Illinois, Urbana-Champaign, told Live Science. "You can imagine a photon of light created by nuclear reactions at the center of the sun trying to come out to the sun's surface," he said. "The center of the sun is extremely hot, and so there are a lot of free electrons present. This means light cannot travel in straight lines." The distance from the center of the sun to its surface is about 432,450 miles (696,000 kilometers). The speed of light in a vacuum is about 186,000 miles per second (300,000 km/s), but in the sun, "it takes about 1 million to 2 million years for light to escape from the center of the sun to its surface," Raghunathan said. However, about 380,000 years after the Big Bang, the expansion of the universe let the cosmos cool enough for atomic nuclei to glom onto electrons. "When that happens, all those electrons are no longer free," Layden said. "This happens at about 3,000 Kelvin [4,940 degrees Fahrenheit, or 2,725 degrees Celsius], the surface temperature of a coolish reddish star." Within a short number of years, "everything goes from being a hot dense soup to a clear universe where light can travel freely," Layden said. "At that moment, the first photons in the universe can escape." The light typical of the universe when it was about 3,000 kelvins was in near-infrared to visible wavelengths, Layden noted. However, as the cosmos expanded over the course of more than 13 billion years and cooled to an average temperature of about 2.73 Kelvin (minus 455 F, or minus 270 C), the universe's first light stretched to longer microwave wavelengths. Astronomers first detected this leftover radiation from the Big Bang, called the cosmic microwave background, in 1964. RELATED MYSTERIES —What is the smallest particle in the universe? (What about the largest?) —What would happen if the speed of light were much lower? —Where do electrons get energy to spin around an atom's nucleus? Analyzing these microwaves has yielded many insights. For instance, the gravitational pull of galaxies can distort light — a phenomenon called gravitational lensing. Examining the amount of distortion the cosmic microwave background has experienced at different points in the sky can help scientists reconstruct the large-scale structure of the universe — the arrangement of galaxies and the giant voids between them across the cosmos, Raghunathan said. After the light from the Big Bang was released, the universe experienced a period known as the cosmic dark ages. Eventually, after millions of years, the gravitational pull of clouds of gas led these clumps of matter to collapse in on themselves. "This created the first generation of stars, and the universe had galaxies full of stars by about 1 billion years after the Big Bang, beginning the cosmic dawn," Layden said.
Associated Press
16-06-2025
- Science
- Associated Press
The Phenomenological Origin of Photons in Classical Fields: Cheyney-backed Research Transforms Understanding of Light
LITLINGTON, England--(BUSINESS WIRE)--Jun 16, 2025-- A recent research article supported by Cheyney Design and Development Ltd. presents a revolutionary theory on light. Dr. Dhiraj Sinha, a faculty member at Plaksha University, has published an article in Annals of Physics, a peer-reviewed journal from Elsevier, where his discovery on a critical link between the ideas of Maxwell and Einstein on light has been disclosed. It transforms a century-old scientific theory on the nature of light, while forging a vital link between classical and quantum theories of light. The study is derived from a prior article published in Physical Review Letters, where Dr. Sinha showed that electromagnetic radiation is generated under explicit symmetry breaking of the electrodynamic field. The research project, funded by Cheyney, presented an integrated theoretical framework on the generation of radiation, ranging from radio to optical frequencies. This press release features multimedia. View the full release here: Electrons ejected under photoexcitation from a metallic surface The nature of light has remained one of the most intriguing scientific challenges. Newton's conjecture that light consists of particles was replaced by the wave theory of light pioneered by Young and Fresnel, which found additional support from Maxwell in 1865, who postulated that light is an electromagnetic wave. It was experimentally verified by Heinrich Hertz in 1887, but later experiments on the photoelectric effect where electrons are generated when light falls on a metal plate, led to new questions. Einstein's heuristic argument that light consists of packets of energy or light quanta could explain the energy dependence of electrons on the frequency of light in the photoelectric effect. This led to the revolutionary perspective that light behaves like a wave in free space and like particles under interaction with matter. Currently, the scientific establishment believes that light-matter interaction can only be explained by the concept of photons which has no direct theoretical links to Maxwell's electromagnetic field theory. In the recent research article, Dr. Dhiraj Sinha has presented his discovery that photons directly emerge from Maxwell's fields. He has used the Maxwell-Faraday equation to substantiate his point which says that the time varying magnetic field of electromagnetic radiation generates an electric potential defined by ds/dt where ds is the differential change in magnetic flux s of radiation over a differential change in time dt. Dr. Sinha argues that an electron of charge e is energised by the electric potential generated by light which is expressed as W=eds/dt. The frequency domain or phasor representation of electron's energy is esw, where w is angular frequency of light. Dr. Sinha's fundamental discovery is associated with correlating ' esw' to Einstein's expression on the energy of a photon ħw, where ħ is the reduced Planck's constant. Thus, he has demonstrated that Faraday's law of electromagnetic induction plays the central role in energising electrons from the changing magnetic flux of radiation field. This theoretical discovery by Dr. Sinha implies that photons are directly generated from Maxwell's fields while assuming magnetic flux quantisation, which has been observed in superconducting loops as well as two-dimensional electron gas systems. Thus, light-matter interaction can be explained using Maxwell's fields. The idea has received strong support from a team of well-known physicists spanning many universities. Jorge Hirsch, professor of physics at University of California San Diego, wrote a letter of support for the editorial board members. Steven Verrall, former faculty member at University of Wisconsin-La Crosse, says, 'Dr. Sinha provides a new semiclassical approach to modelling quantum systems. His unique approach may ultimately add valuable insights to the continued development of semiclassical effective field theories in low energy physics.' Lawrence Horwitz, professor emeritus at the University of Tel Aviv, notes, 'This article is indeed a valuable contribution to the theory of photons and electrons.' Richard Muller, professor of physics at University of California Berkeley and Faculty Senior Scientist at Lawrence Berkeley National Laboratory, commented, 'The ideas are intriguing and they address the most fundamental of the non-resolved issues of quantum physics including the particle/wave duality and the meaning of measurement.' Dr. Sinha's discovery provides a revolutionary structure towards integrating the principles of classical electromagnetism into modern photonic devices. It can have a transformational impact in optics, photonics and electronics. It implies that the devices like solar cells, lasers, light-emitting diodes, along with radio antennas which operate on the principle of Maxwell's equations can be integrated on the same platform. The work offers a novel framework for one of the most radically transformative pathways towards their seamless integration. Dr. Richard Parmee, founder of Cheyney Design and Development, stated, 'Cheyney is proud to support Dr. Sinha's pioneering work, which has the potential to transform our understanding of light and its applications. Our mission is to champion early-stage innovations that push the frontiers of knowledge, and this research exemplifies our vision of nurturing high-impact scientific advancements.' Additional Information 1. Sinha, D. Electrodynamic excitation of electrons. Annals of Physics, 473, 169893 (2025). 2. Sinha, D., & Amaratunga, G. A. Electromagnetic radiation under explicit symmetry breaking. Physical Review Letters, 114, 147701 (2015). About Cheyney Design & Development Ltd. Cheyney Design & Development Ltd, Litlington, UK, founded by Dr. Richard Parmee, is at the forefront of innovations in X-ray inspection technology. Its patented, cutting-edge technology and advanced stochastic algorithms position it as technical leader in the X-ray inspection arena. Cheyney is dedicated to supporting early-stage innovations with transformative potential in science and engineering. View source version on [email protected] KEYWORD: GERMANY EUROPE IRELAND UNITED KINGDOM INDUSTRY KEYWORD: RESEARCH OTHER ENERGY ALTERNATIVE ENERGY ENERGY TECHNOLOGY OTHER EDUCATION UNIVERSITY EDUCATION SCIENCE PHOTOGRAPHY AUDIO/VIDEO OTHER TECHNOLOGY OTHER SCIENCE SOURCE: Cheyney Design and Development Ltd. Copyright Business Wire 2025. PUB: 06/16/2025 04:35 AM/DISC: 06/16/2025 04:34 AM
Gizmodo
25-05-2025
- Science
- Gizmodo
Does Light Traveling Through Space Wear Out?
My telescope, set up for astrophotography in my light-polluted San Diego backyard, was pointed at a galaxy unfathomably far from Earth. My wife, Cristina, walked up just as the first space photo streamed to my tablet. It sparkled on the screen in front of us. 'That's the Pinwheel galaxy,' I said. The name is derived from its shape–albeit this pinwheel contains about a trillion stars. The light from the Pinwheel traveled for 25 million years across the universe–about 150 quintillion miles–to get to my telescope. My wife wondered: 'Doesn't light get tired during such a long journey?' Her curiosity triggered a thought-provoking conversation about light. Ultimately, why doesn't light wear out and lose energy over time? Let's talk about light I am an astrophysicist, and one of the first things I learned in my studies is how light often behaves in ways that defy our intuitions. Light is electromagnetic radiation: basically, an electric wave and a magnetic wave coupled together and traveling through space-time. It has no mass. That point is critical because the mass of an object, whether a speck of dust or a spaceship, limits the top speed it can travel through space. But because light is massless, it's able to reach the maximum speed limit in a vacuum–about 186,000 miles (300,000 kilometers) per second, or almost 6 trillion miles per year (9.6 trillion kilometers). Nothing traveling through space is faster. To put that into perspective: In the time it takes you to blink your eyes, a particle of light travels around the circumference of the Earth more than twice. As incredibly fast as that is, space is incredibly spread out. Light from the Sun, which is 93 million miles (about 150 million kilometers) from Earth, takes just over eight minutes to reach us. In other words, the sunlight you see is eight minutes old. Alpha Centauri, the nearest star to us after the Sun, is 26 trillion miles away (about 41 trillion kilometers). So by the time you see it in the night sky, its light is just over four years old. Or, as astronomers say, it's four light years away. With those enormous distances in mind, consider Cristina's question: How can light travel across the universe and not slowly lose energy? Actually, some light does lose energy. This happens when it bounces off something, such as interstellar dust, and is scattered about. But most light just goes and goes, without colliding with anything. This is almost always the case because space is mostly empty–nothingness. So there's nothing in the way. When light travels unimpeded, it loses no energy. It can maintain that 186,000-mile-per-second speed forever. It's about time Here's another concept: Picture yourself as an astronaut on board the International Space Station. You're orbiting at 17,000 miles (about 27,000 kilometers) per hour. Compared with someone on Earth, your wristwatch will tick 0.01 seconds slower over one year. That's an example of time dilation–time moving at different speeds under different conditions. If you're moving really fast, or close to a large gravitational field, your clock will tick more slowly than someone moving slower than you, or who is further from a large gravitational field. To say it succinctly, time is relative. Now consider that light is inextricably connected to time. Picture sitting on a photon, a fundamental particle of light; here, you'd experience maximum time dilation. Everyone on Earth would clock you at the speed of light, but from your reference frame, time would completely stop. That's because the 'clocks' measuring time are in two different places going vastly different speeds: the photon moving at the speed of light, and the comparatively slowpoke speed of Earth going around the Sun. What's more, when you're traveling at or close to the speed of light, the distance between where you are and where you're going gets shorter. That is, space itself becomes more compact in the direction of motion–so the faster you can go, the shorter your journey has to be. In other words, for the photon, space gets squished. Which brings us back to my picture of the Pinwheel galaxy. From the photon's perspective, a star within the galaxy emitted it, and then a single pixel in my backyard camera absorbed it, at exactly the same time. Because space is squished, to the photon the journey was infinitely fast and infinitely short, a tiny fraction of a second. But from our perspective on Earth, the photon left the galaxy 25 million years ago and traveled 25 million light years across space until it landed on my tablet in my backyard. And there, on a cool spring night, its stunning image inspired a delightful conversation between a nerdy scientist and his curious wife. Jarred Roberts, Project Scientist, University of California, San Diego. This article is republished from The Conversation under a Creative Commons license. Read the original article.
Times
14-05-2025
- Science
- Times
The World, the Universe and Us review — endearingly nerdy science news
A recent episode of New Scientist's ambitiously titled podcast The World, the Universe and Us begins with a shamefaced confession. 'We got the whole nature of light wrong,' Dr Rowan Hooper says. Hang on. Not just a bit of the nature of light, but the whole nature of light? I wouldn't like to have to report that to my boss if I were a scientist — I get nervous enough about making spelling errors. Imagine having to fess up to getting the whole nature of light wrong. I can only imagine the performance review that followed that clanger. Thankfully, it turns out that getting 'the whole nature of light wrong' is less dramatic than it sounds. The point at issue is the interpretation of
