Latest news with #physicists
Yahoo
3 days ago
- General
- Yahoo
The Universe's Most Powerful Cosmic Rays May Finally Be Explained
Somewhere in our galaxy are engines capable of driving atomic fragments to velocities that come within a whisker of lightspeed. The explosive deaths of stars seems like a natural place to search for sources of these highly energetic cosmic bullets, yet when it comes to the most powerful particles, researchers have had their doubts. Numerical simulations by a small international team of physicists may yet save the supernova theory of cosmic ray emissions at the highest of energies, suggesting there is a brief period where a collapsing star could still become the Universe's most extreme accelerator. For more than a century, scientists have scanned the skies for phenomena that may be responsible for the relatively constant showers of atomic nuclei and occasional electrons that pepper our planet. Simply following their trajectory would be like picking up a bottle on the beach and looking to the horizon for its home. The charges of most cosmic rays put them at the mercy of a turbulent ocean of magnetic fields across the galaxy and beyond, leaving researchers to search for other clues. A mere few thousand light years away in our galactic backyard, the historic supernova known as Tycho's star has been studied for signs of physics capable of accelerating charged particles. In 1572, astronomers marveled at the star's sudden brightening, now understood to be the final hoorah of a white dwarf ending its life in a thermonuclear catastrophe. As its core collapsed under its own weight, the burst of heat and radiation slammed into the shell of surrounding gases, generating immense magnetic fields. In 2023 researchers published their analysis on those fields, finding their ability to generate cosmic rays was "significantly smaller" than those expected of existing models. While this doesn't rule out collapsing stars as potential particle accelerators, it does raise questions on just how much power they can provide. Every now and then, Earth is struck by some true monsters – particles that are up to a thousand times more powerful than anything our own technology has been capable of generating. These peta-electronvolt (PeV) energies are the work of hypothetical cosmic engines dubbed PeVatrons. According to astrophysicists Robert Brose from the University of Potsdam in Germany, Iurii Sushch from the Spanish Centre for Energy, Environmental and Technological Research, and Jonathan Mackey from the Dublin Institute for Advanced Studies, dying stars just might be the mysterious PeVatrons scientists have been searching for. For it to work, the dying star first needs to cough up enough material to form a dense shell around itself. Then, at the moment of supernova the rapidly expanding shock wave smashes into this dense environment, generating the necessary magnetic turbulence to whip nuclei and electrons towards PeV-levels of acceleration. The critical element, they claim, is timing – only within its first decade or two is the surrounding shell dense enough to provide the amount of turbulence required for particles to reach the highest of energies. "It is possible that only very young supernova remnants evolving in dense environments may satisfy the necessary conditions to accelerate particles to PeV energies," the team writes. Had Tycho's star held its breath for just another few centuries, astrophysicists may have recorded a shower of cosmic rays at the highest of magnitudes. Perhaps in the near future, the violent end of another nearby star just might give us the opportunity they need to solve the perplexing mystery of PeVatrons once and for all. This research has been accepted for publication in Astronomy & Astrophysics. China's Tianwen-2 Launches to Grab First 'Living Fossil' Asteroid Samples Scientists Have Clear Evidence of Martian Atmosphere 'Sputtering' Chance X-Ray Discovery Reveals Mystery Object 15,000 Light Years Away
Yahoo
18-05-2025
- Politics
- Yahoo
Kashmir conflict: A look at how India and Pakistan became nuclear powers
India and Pakistan, two nuclear-armed nations, saw a decades-old conflict reignite May 7 as a terror attack in the disputed region of Kashmir led India to carry out cross-border airstrikes. India's government blames Pakistan for an April 22 terror attack that killed 26 tourists in India-administered Kashmir. Islamabad denies involvement. The Pakistani military claims it shot down Indian planes during the airstrikes and it fired artillery across the disputed border. Pakistan promised further retaliation. More: Why India attacked Pakistan, its neighbor and nuclear rival The rising tensions have alarmed world leaders, to include President Donald Trump. Trump told reporters in the Oval Office on May 7 the fighting is "so terrible" and said he wants the warring countries to work it out. "I get along with both. I know both very well," he said. "I want to see them stop. And hopefully they can stop now. They've gone tit-for-tat, so hopefully they can stop now." He added: "And if I can do anything to help, I will − I will be there." Although Trump did not directly reference the possibility of a nuclear exchange between the two countries, concern about the countries' nuclear arsenals has historically spiked during perious of conflict. Here's how India and Pakistan developed their nuclear weapons. Related: Putin, Ukraine, long-range missiles and why there's talk about WWIII In the late 1950s, India established its nuclear program with assistance from the U.S. and Canada, who provided nuclear reactors and nuclear fuel. The program was explicitly peaceful in its stated intent, and India agreed to safeguards meant to prevent the reactors and their fuel from being used for weapons. Nuclear nonproliferation experts say India exploited a loophole in the safeguards when it began secretly reprocessing spent fuel into plutonium in the 1960s − one of the two main methods of producing fissile material for a nuclear weapon. New Delhi's secret bomb development program officially began in 1964, but it reached a fever pitch by the early 1970s when multiple teams of Indian physicists simultaneously developed different weapons components needed to create a nuclear explosion from the reprocessed plutonium. More: Timeline of India and Pakistan's military conflicts The country's first nuclear test, code-named Smiling Buddha, took place in 1974 in a remote portion of the country's northwest. India claimed the explosion was "peaceful," but the international community concluded (and lead scientists later revealed) they had detonated a bomb. In response, Canada halted nuclear cooperation with India. Although the U.S. did not impose sanctions or terminate nuclear assistance to New Delhi, the failure of the safeguards helped inspire Congress to pass the 1978 Nuclear Nonproliferation Act. Over the ensuing decades, India developed stronger thermonuclear weapons and − to the world's surprise − successfully tested them in 1998. Today, New Delhi controls around 172 nuclear weapons, according to the Arms Control Association. The story of Pakistan's nuclear weapons program all but begins with A.Q. Khan, a metallurgist born in pre-partition India and raised in newly independent Pakistan. Khan pursued graduate study in Europe and in 1972, he started working for a nuclear engineering consulting firm in Amsterdam where he gained access to information on ultra-centrifuges that were able to highly enrich radioactive uranium — the second main method of producing fissile material for a nuclear weapon. More: India strikes Pakistan in aftermath of Kashmir tourist killings After India handed Pakistan a humiliating military defeat in a 1971 war and conducted the Smiling Buddha nuclear test in 1974, Khan wrote to Pakistan's prime minister, Zulfikar Ali Bhutto, and offered to spearhead a nuclear weapons program for his home country. Khan successfully smuggled information, photos, blueprints, and even components of the centrifuges to the Pakistan embassy in the Netherlanda before successfully escaping to lead the program. Khan led secret production efforts (in parallel to another Pakistani weapons program) that successfully yielded nuclear warheads in 1986, though they were not tested until 1998 − mere weeks after India tested its new thermonuclear weapons. Khan also was linked with distributing nuclear weapons technology to rogue states including North Korea, Iran, and Libya. Pakistan today has approximately 170 nuclear warheads, according to the Arms Control Association. Contributing: Francesca Chambers If you have news tips related to nuclear threats or U.S. national security, please contact Davis Winkie via email at dwinkie@ or via the Signal encrypted messaging app at 770-539-3257. Davis Winkie's role covering nuclear threats and national security at USA TODAY is supported by a partnership with Outrider Foundation and Journalism Funding Partners. Funders do not provide editorial input. This article originally appeared on USA TODAY: How India and Pakistan got their nuclear weapons
The Independent
13-05-2025
- Science
- The Independent
Scientists accidentally achieve alchemy by turning lead into gold
Medieval alchemists dreamed of transmuting lead into gold. Today, we know that lead and gold are different elements, and no amount of chemistry can turn one into the other. But our modern knowledge tells us the basic difference between an atom of lead and an atom of gold: the lead atom contains exactly three more protons. So can we create a gold atom by simply pulling three protons out of a lead atom? As it turns out, we can. But it's not easy. While smashing lead atoms into each other at extremely high speeds in an effort to mimic the state of the universe just after the Big Bang, physicists working on the ALICE experiment at the Large Hadron Collider in Switzerland incidentally produced small amounts of gold. Extremely small amounts, in fact: a total of some 29 trillionths of a gram. How to steal a proton Protons are found in the nucleus of an atom. How can they be pulled out? Well, protons have an electric charge, which means an electric field can pull or push them around. Placing an atomic nucleus in an electric field could do it. However, nuclei are held together by a very strong force with a very short range, imaginatively known as the strong nuclear force. This means an extremely powerful electric field is required to pull out protons – about a million times stronger than the electric fields that create lightning bolts in the atmosphere. The way the scientists created this field was to fire beams of lead nuclei at each other at incredibly high speeds – almost the speed of light. The magic of a near-miss When the lead nuclei have a head-on collision, the strong nuclear force comes into play and they end up getting completely destroyed. But more commonly the nuclei have a near miss, and only affect each other via the electromagnetic force. The strength of an electric field drops off very quickly as you move away from an object with an electric charge (such as a proton). But at very short distances, even a tiny charge can create a very strong field. So when one lead nucleus just grazes past another, the electric field between them is huge. The rapidly changing field between the nuclei makes them vibrate and occasionally spit out some protons. If one of them spits out exactly three protons, the lead nucleus has turned into gold. Counting protons So if you have turned a lead atom into gold, how do you know? In the ALICE experiment, they use special detectors called zero-degree calorimeters to count the protons stripped out of the lead nuclei. They can't observe the gold nuclei themselves, so they only know about them indirectly. The ALICE scientists calculate that, while they are colliding beams of lead nuclei, they produce about 89,000 gold nuclei per second. They also observed the production of other elements: thallium, which is what you get when you take one proton from lead, as well as mercury (two protons). An alchemical nuisance Once a lead nucleus has transformed by losing protons, it is no longer on the perfect orbit that keeps it circulating inside the vacuum beam pipe of the Large Hadron Collider. In a matter of microseconds it will collide with the walls. This effect makes the beam less intense over time. So for scientists, the production of gold at the collider is in fact more of a nuisance than a blessing. However, understanding this accidental alchemy is essential for making sense of experiments – and for designing the even bigger experiments of the future. Ulrik Egede is a Professor of Physics at Monash University
Yahoo
11-05-2025
- Science
- Yahoo
Could a human enter a black hole to study it?
Curious Kids is a series for children of all ages. If you have a question you'd like an expert to answer, send it to CuriousKidsUS@ Could a human enter a black hole to study it? – Pulkeet, age 12, Bahadurgarh, Haryana, India To solve the mysteries of black holes, a human should just venture into one. However, there is a rather complicated catch: A human can do this only if the respective black hole is supermassive and isolated, and if the person entering the black hole does not expect to report the findings to anyone in the entire universe. We are both physicists who study black holes, albeit from a very safe distance. Black holes are among the most abundant astrophysical objects in our universe. These intriguing objects appear to be an essential ingredient in the evolution of the universe, from the Big Bang till present day. They probably had an impact on the formation of human life in our own galaxy. The universe is littered with a vast zoo of different types of black holes. They can vary by size and be electrically charged, the same way electrons or protons are in atoms. Some black holes actually spin. There are two types of black holes that are relevant to our discussion. The first does not rotate, is electrically neutral – that is, not positively or negatively charged – and has the mass of our Sun. The second type is a supermassive black hole, with a mass of millions to even billions times greater than that of our Sun. Besides the mass difference between these two types of black holes, what also differentiates them is the distance from their center to their 'event horizon' – a measure called radial distance. The event horizon of a black hole is the point of no return. Anything that passes this point will be swallowed by the black hole and forever vanish from our known universe. At the event horizon, the black hole's gravity is so powerful that no amount of mechanical force can overcome or counteract it. Even light, the fastest-moving thing in our universe, cannot escape – hence the term 'black hole.' The radial size of the event horizon depends on the mass of the respective black hole and is key for a person to survive falling into one. For a black hole with a mass of our Sun (one solar mass), the event horizon will have a radius of just under 2 miles. The supermassive black hole at the center of our Milky Way galaxy, by contrast, has a mass of roughly 4 million solar masses, and it has an event horizon with a radius of 7.3 million miles or 17 solar radii. Thus, someone falling into a stellar-size black hole will get much, much closer to the black hole's center before passing the event horizon, as opposed to falling into a supermassive black hole. This implies, due to the closeness of the black hole's center, that the black hole's pull on a person will differ by a factor of 1,000 billion times between head and toe, depending on which is leading the free fall. In other words, if the person is falling feet first, as they approach the event horizon of a stellar mass black hole, the gravitational pull on their feet will be exponentially larger compared to the black hole's tug on their head. The person would experience spaghettification, and most likely not survive being stretched into a long, thin noodlelike shape. Now, a person falling into a supermassive black hole would reach the event horizon much farther from the the central source of gravitational pull, which means that the difference in gravitational pull between head and toe is nearly zero. Thus, the person would pass through the event horizon unaffected, not be stretched into a long, thin noodle, survive and float painlessly past the black hole's horizon. Most black holes that we observe in the universe are surrounded by very hot disks of material, mostly comprising gas and dust or other objects like stars and planets that got too close to the horizon and fell into the black hole. These disks are called accretion disks and are very hot and turbulent. They are most certainly not hospitable and would make traveling into the black hole extremely dangerous. To enter one safely, you would need to find a supermassive black hole that is completely isolated and not feeding on surrounding material, gas and or even stars. Now, if a person found an isolated supermassive black hole suitable for scientific study and decided to venture in, everything observed or measured of the black hole interior would be confined within the black hole's event horizon. Keeping in mind that nothing can escape the gravitational pull beyond the event horizon, the in-falling person would not be able to send any information about their findings back out beyond this horizon. Their journey and findings would be lost to the rest of the entire universe for all time. But they would enjoy the adventure, for as long as they survived … maybe …. Hello, curious kids! Do you have a question you'd like an expert to answer? Ask an adult to send your question to CuriousKidsUS@ Please tell us your name, age and the city where you live. And since curiosity has no age limit – adults, let us know what you're wondering, too. We won't be able to answer every question, but we will do our best. This article is republished from The Conversation, a nonprofit, independent news organization bringing you facts and trustworthy analysis to help you make sense of our complex world. It was written by: Leo Rodriguez, Grinnell College and Shanshan Rodriguez, Grinnell College Read more: Supermassive black hole at the center of our galaxy may have a friend The scariest things in the universe are black holes – and here are 3 reasons Rotating black holes may serve as gentle portals for hyperspace travel The authors do not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.
Yahoo
10-05-2025
- Science
- Yahoo
Is alchemy real? Physicists turn lead into gold using the Large Hadron Collider
The Brief CERN physicists created gold atoms by smashing lead ions together at near-light speed inside the Large Hadron Collider. The transmutation occurs when lead nuclei lose three protons, transforming into gold, but the resulting atoms last only about a microsecond. Between 2015 and 2018, 86 billion gold nuclei were created—equivalent to just 29 trillionths of a gram. At CERN's Large Hadron Collider (LHC), the dream of alchemists has become a fleeting reality. Physicists with the ALICE collaboration have successfully turned lead into gold — not through magic or chemistry, but by smashing lead nuclei together at near-light speeds. The experiment produced gold atoms by causing the nuclei to eject three protons through a process called electromagnetic dissociation. When two lead ions narrowly miss a head-on collision inside the LHC, their intense electromagnetic fields interact. In some of these near-misses, the collision creates a pulse of energy that strips three protons from a lead atom (which has 82 protons), turning it into gold (which has 79). Using ALICE's Zero Degree Calorimeters (ZDCs), the team tracked these events and filtered them out from the background of the LHC's usual particle chaos. Their analysis, published May 7 in Physical Review Journals, measured gold production at an estimated rate of 89,000 nuclei per second during the collider's latest run. By the numbers Despite the impressive physics, the actual gold yield is vanishingly small. During the LHC's second run (2015–2018), around 86 billion gold nuclei were created — totaling about 29 picograms (that's 29 trillionths of a gram). Even with current upgrades doubling production in Run 3, the gold still exists only for a microsecond before disintegrating or smashing into equipment. To put it simply: you'd need trillions of years of collisions just to make enough gold for a single earring. What they're saying "It is impressive to see that our detectors can handle head-on collisions producing thousands of particles, while also being sensitive to collisions where only a few particles are produced at a time," said ALICE spokesperson Marco Van Leeuwen. Uliana Dmitrieva, a physicist with ALICE, added: "Thanks to the unique capabilities of the ALICE ZDCs, the present analysis is the first to systematically detect and analyze the signature of gold production at the LHC experimentally." "The results also test and improve theoretical models of electromagnetic dissociation," said physicist John Jowett, noting that these insights could help address one of the LHC's biggest challenges: predicting and managing beam losses. Big picture view While no one is cashing in on atom-sized bits of gold, this research offers more than just symbolic significance. It improves scientists' understanding of how matter behaves at extreme energies and helps validate models used to run the LHC safely and efficiently. It also sheds light on rare particle interactions — including those that may mirror conditions just moments after the Big Bang. In chasing the mythical goals of alchemy, modern physics is once again unlocking deeper truths about the nature of the universe. The Source This article is based on reporting from Physical Review Journals and official CERN releases, with contextual coverage from Nature and ALICE collaboration statements. This story was reported from Los Angeles.
