Latest news with #quantummechanics
Yahoo
30-07-2025
- Science
- Yahoo
Physicists still divided about quantum world, 100 years on
The theory of quantum mechanics has transformed daily life since being proposed a century ago, yet how it works remains a mystery -- and physicists are deeply divided about what is actually going on, a survey in the journal Nature said Wednesday. "Shut up and calculate!" is a famous quote in quantum physics that illustrates the frustration of scientists struggling to unravel one of the world's great paradoxes. For the last century, equations based on quantum mechanics have consistently and accurately described the behaviour of extremely small objects. However, no one knows what is happening in the physical reality behind the mathematics. The problem started at the turn of the 20th century, when scientists realised that the classical principles of physics did not apply to things on the level on atoms. Bafflingly, photons and electrons appear to behave like both particles and waves. They can also be in different positions simultaneously -- and have different speeds or levels of energy. In 1925, Austrian physicist Erwin Schroedinger and Germany's Werner Heisenberg developed a set of complex mathematical tools that describe quantum mechanics using probabilities. This "wave function" made it possible to predict the results of measurements of a particle. These equations led to the development of a huge amount of modern technology, including lasers, LED lights, MRI scanners and the transistors used in computers and phones. But the question remained: what exactly is happening in the world beyond the maths? - A confusing cat - To mark the 100th year of quantum mechanics, many of the world's leading physicists gathered last month on the German island of Heligoland, where Heisenberg wrote his famous equation. More than 1,100 of them responded to a survey conducted by the leading scientific journal Nature. The results showed there is a "striking lack of consensus among physicists about what quantum theory says about reality", Nature said in a statement. More than a third -- 36 percent -- of the respondents favoured the mostly widely accepted theory, known as the Copenhagen interpretation. In the classical world, everything has defined properties -- such as position or speed -- whether we observe them or not. But this is not the case in the quantum realm, according to the Copenhagen interpretation developed by Heisenberg and Danish physicist Niels Bohr in the 1920s. It is only when an observer measures a quantum object that it settles on a specific state from the possible options, goes the theory. This is described as its wave function "collapsing" into a single possibility. The most famous depiction of this idea is Schroedinger's cat, which remains simultaneously alive and dead in a box -- until someone peeks inside. The Copenhagen interpretation "is the simplest we have", Brazilian physics philosopher Decio Krause told Nature after responding to the survey. Despite the theory's problems -- such as not explaining why measurement has this effect -- the alternatives "present other problems which, to me, are worse," he said. - Enter the multiverse - But the majority of the physicists supported other ideas. Fifteen percent of the respondents opted for the "many worlds" interpretation, one of several theories in physics that propose we live in a multiverse. It asserts that the wave function does not collapse, but instead branches off into as many universes as there are possible outcomes. So when an observer measures a particle, they get the position for their world -- but it is in all other possible positions across many parallel universes. "It requires a dramatic readjustment of our intuitions about the world, but to me that's just what we should expect from a fundamental theory of reality," US theoretical physicist Sean Carroll said in the survey. The quantum experts were split on other big questions facing the field. Is there some kind of boundary between the quantum and classical worlds, where the laws of physics suddenly change? Forty-five percent of the physicists responded yes to this question -- and the exact same percentage responded no. Just 24 percent said they were confident the quantum interpretation they chose was correct. And three quarters believed that it will be replaced by a more comprehensive theory one day. ber/dl/jj Solve the daily Crossword
France 24
30-07-2025
- Science
- France 24
Physicists still divided about quantum world, 100 years on
"Shut up and calculate!" is a famous quote in quantum physics that illustrates the frustration of scientists struggling to unravel one of the world's great paradoxes. For the last century, equations based on quantum mechanics have consistently and accurately described the behaviour of extremely small objects. However, no one knows what is happening in the physical reality behind the mathematics. The problem started at the turn of the 20th century, when scientists realised that the classical principles of physics did not apply to things on the level on atoms. Bafflingly, photons and electrons appear to behave like both particles and waves. They can also be in different positions simultaneously -- and have different speeds or levels of energy. In 1925, Austrian physicist Erwin Schroedinger and Germany's Werner Heisenberg developed a set of complex mathematical tools that describe quantum mechanics using probabilities. This "wave function" made it possible to predict the results of measurements of a particle. These equations led to the development of a huge amount of modern technology, including lasers, LED lights, MRI scanners and the transistors used in computers and phones. But the question remained: what exactly is happening in the world beyond the maths? A confusing cat To mark the 100th year of quantum mechanics, many of the world's leading physicists gathered last month on the German island of Heligoland, where Heisenberg wrote his famous equation. More than 1,100 of them responded to a survey conducted by the leading scientific journal Nature. The results showed there is a "striking lack of consensus among physicists about what quantum theory says about reality", Nature said in a statement. More than a third -- 36 percent -- of the respondents favoured the mostly widely accepted theory, known as the Copenhagen interpretation. In the classical world, everything has defined properties -- such as position or speed -- whether we observe them or not. But this is not the case in the quantum realm, according to the Copenhagen interpretation developed by Heisenberg and Danish physicist Niels Bohr in the 1920s. It is only when an observer measures a quantum object that it settles on a specific state from the possible options, goes the theory. This is described as its wave function "collapsing" into a single possibility. The most famous depiction of this idea is Schroedinger's cat, which remains simultaneously alive and dead in a box -- until someone peeks inside. The Copenhagen interpretation "is the simplest we have", Brazilian physics philosopher Decio Krause told Nature after responding to the survey. Despite the theory's problems -- such as not explaining why measurement has this effect -- the alternatives "present other problems which, to me, are worse," he said. Enter the multiverse But the majority of the physicists supported other ideas. Fifteen percent of the respondents opted for the "many worlds" interpretation, one of several theories in physics that propose we live in a multiverse. It asserts that the wave function does not collapse, but instead branches off into as many universes as there are possible outcomes. So when an observer measures a particle, they get the position for their world -- but it is in all other possible positions across many parallel universes. "It requires a dramatic readjustment of our intuitions about the world, but to me that's just what we should expect from a fundamental theory of reality," US theoretical physicist Sean Carroll said in the survey. The quantum experts were split on other big questions facing the field. Is there some kind of boundary between the quantum and classical worlds, where the laws of physics suddenly change? Forty-five percent of the physicists responded yes to this question -- and the exact same percentage responded no. Just 24 percent said they were confident the quantum interpretation they chose was correct. And three quarters believed that it will be replaced by a more comprehensive theory one day.
ABC News
28-07-2025
- Science
- ABC News
Quantum mechanic physics theory was born 100 years ago, thanks to Heisenberg's hay fever
In 1925, a young German physicist fled to the treeless island of Helgoland in the North Sea to ease a severe bout of hay fever. With nothing but daily walks and long swims to distract him, 23-year-old Werner Heisenberg had time to grapple with a conundrum. The macro world — of apples falling from trees — behaved differently to the micro world — of atoms and their subatomic components. While the macro world could be explained by Sir Isaac Newton's laws of motion, nature's tiniest particles seemed lawless. As Heisenberg later wrote in his memoir, all attempts to make sense of their behaviour with "older physics" seemed doomed to fail. And so he arrived to the bracing sea air of Helgoland — "far from blossoms and meadows" — determined to find a mathematical solution. A month after this trip to Helgoland, on July 29, Heisenberg submitted a paper considered to be the advent of quantum mechanics. In the years that followed, the greatest minds in physics wrestled with what it all meant. As a consequence, they discovered some of the strangest pillars of quantum physics. Heisenberg's musings and subsequent writings were triggered by the concept of "quanta", which was introduced at the end of the 19th century. Quanta are discrete packets of energy, and their existence challenged the old view of energy as a continuous phenomenon. Heisenberg managed to come up with a mathematical formulation to make sense of this shift in 1925 with what he called his "matrix mechanics". It was the first consistent and logical formulation of quantum mechanics, but it was also incredibly dense. Meanwhile, Austrian-Irish theoretical physicist Erwin Schrödinger was also spending stretches of 1925 in seclusion, receiving treatment for tuberculosis at a high-altitude sanatorium in Switzerland. He was working on his own formulation of quantum mechanics that would later be known as the wave equation. The wave equation was easier to grasp than Heisenberg's matrices, and as a result it's still used today to understand the behaviour of particles. "It was a big year," mathematician and historian Robyn Arianrhod, an affiliate of Monash University, says. "It was the year quantum mechanics became formalised … and then all sorts of consequences happened when trying to interpret those two different formalisms." That's because it's not always immediately clear what a written equation means when it's applied to the physical world. Schrödinger initially imagined the wave in his wave equation as a physical phenomenon, like a soundwave or an ocean wave. But Schrödinger's interpretation of his own equation was wrong. "Really what the waves are predicting are probabilities," Dr Arianrhod says. If you picture a very basic drawing of a wave on a piece of paper, the peaks and troughs will indicate where a particle is more or less likely to be found. But here's the strange thing — until observed, the particle doesn't have a precise location. It exists in all of those possible locations at once. This is called superposition. This concept is often explained through the Schrödinger's cat thought experiment, where the cat is both alive and dead at the same time. "And that was a really interesting and strange idea," Dr Arianrhod says. So strange it started a decades-long debate between two titans of physics: Albert Einstein and Danish physicist Niels Bohr. The world's greatest physicists met to discuss this new quantum mechanics at the Solvay Conference on Physics in 1927. Two camps had emerged, and it was on the sidelines of this conference that they battled it out. Bohr and his followers accepted we could only ever know statistical likelihoods when it came to the properties of particles. But Einstein could not accept this — he did not believe God was "playing dice" with the very building blocks of reality itself. So during mealtimes, or while walking between the hotel and the conference venue, the two men debated. "Every morning Einstein was like a jack-in-the-box, jumping up with fresh new thought experiments, trying to show the limitations of quantum theory," Dr Arianrhod says. "And every time, often after sleepless nights, Bohr found a way of answering those objections." After the Solvay Conference, it was assumed Bohr had won the debate. After all, the equations of quantum mechanics worked. "Although everybody thought Bohr had won, Bohr himself kept puzzling over these ideas," Dr Arianrhod says. For years the men swapped letters and thought experiments, trying to figure out how a particle could be in a superposition of every possible state until observed. How could observing a particle alter the particle? Don't particles have inherent properties, whether they're observed or not? It was this observer effect, and Einstein's attempts to undermine it, that led us to the strangest phenomenon of all: entanglement. There's a famous paper in physics known as the Einstein-Podolsky-Rosen (EPR) paradox. In it, the authors present a thought experiment to demonstrate a problem with the observer effect. "Say you've got a red and a green jelly bean and each is in a sealed box," Dr Arianrhod says. "If observer one opens their box and finds a green jelly bean, then observer two knows the colour of their jelly bean in the other box will be red." Easy enough to understand. However, if these are quantum mechanical "entangled" jelly beans, things get more complicated. According to quantum mechanics, neither jelly bean has an inherent colour. They exist in a superposition of both red and green until they're observed. "All we can say for sure is that each jelly bean has a 50 per cent chance of being red and each has a 50 per cent chance of being green," Dr Arianrhod says. If observer one looks inside their box and discovers a red jelly bean, observer two's jelly bean will instantaneously be green. "And this means that the second jelly bean's colour is determined by the first observer. It's not pre-existing," Dr Arianrhod says. The EPR paper concluded: "No reasonable definition of reality could be expected to permit this." Bohr responded to the EPR paper, disagreeing with Einstein's conclusion. And that was that. "The question was essentially put aside for decades," theoretical physicist Eric Cavalcanti of Griffith University says. "Anyone who tried to ask questions about the foundations of quantum mechanics was told to shut up and calculate. However, 30 years after the EPR paper was published, a physicist from Northern Ireland, John Stewart Bell, decided it warranted a closer look. Einstein could not accept what he called "spooky action at a distance". He thought there must be "hidden variables" that determine the colour of the jelly bean, not the observer who simply opened a box and looked inside. So Bell devised a theorem to test Einstein's idea. He found that if you held to Einstein's view of the world, there would be a limit to how much you could know about an entangled pair of particles at any time. For example, you might be able to discover the colours of your jelly beans, but finding out their momentum would be a step too far. The implication was if you breached this upper limit, you proved Einstein wrong. It was doing this that snared Alain Aspect, John Clauser and Anton Zeilinger the 2022 Nobel Prize in Physics. They broke the upper limit, proving that quantum mechanics — in all its weirdness — was sufficient to explain the behaviour of particles. Although Professor Aspect's experiments proved Einstein's view of the world wrong, he didn't gloat about it. "When people say, 'Oh, you showed Einstein wrong', I say, 'Come on, I showed Einstein was great,'" he said in response to the award. After all, if Einstein hadn't asked all those follow-up questions, it's unclear where we might be in our understanding of particle physics, and our use of entanglement in quantum technology. "Bohr's instinct was right," Dr Arianrhod says. This year physicists travelled to Helgoland, tracing Heisenberg's footsteps to mark the 100-year anniversary of his fateful trip. The United Nations declared 2025 the International Year of Quantum Science and Technology. And yet the question that Einstein asked way back in the beginning — what does this all mean? — continues to nag theoretical physicists. What does it mean for particles to be in a superposition of states, or entangled? What does it mean for observers to alter a particle? The maths might work, but it can't make meaning. Part of the problem, Dr Cavalcanti says, is that "we have a lot of answers, but we don't know which one is right. "And each paints a completely different picture of reality." One is the Many Worlds theory, which argues the wave of probabilities doesn't collapse after observation. All probabilities continue to exist, playing out in parallel universes. "There's a branch in which you chose to quit your job and there's a branch where you chose to keep your job," Dr Cavalcanti says. Then there's QBism, which puts the observer's subjective beliefs at the heart of measurement. Your expectations influence the observations you make. And then the de Broglie-Bohm theory, which allows faster-than-light interactions between particles, breaking Einstein's theory of relativity. There are dozens of interpretations out there, each weirder than the next. Any one of them could be true. "Will we ever know? To Bohr, it didn't matter. He didn't really need to know, but Einstein did," Dr Arianrhod says. "There will always be people who want to know. Whether or not nature is going to reveal those secrets is anyone's guess." Listen to 'The centenary of quantum mechanics' and subscribe to The Science Show podcast for more mind-bending science.
Yahoo
27-07-2025
- Business
- Yahoo
Better Quantum Computing Stock: IonQ vs. Rigetti Computing
Key Points IonQ and Rigetti Computing have developed fundamentally different methods to create quantum computers. IonQ aspires to build the internet of the future while Rigetti focuses on commercializing its superconducting qubit technology. Neither IonQ nor Rigetti are profitable, although they have amassed large sums of cash to fund their operations. 10 stocks we like better than IonQ › The quantum computing industry is a promising area to invest in. Quantum machines can complete complex calculations in minutes that would take classical computers centuries, thanks to the power of quantum mechanics. In the sector, IonQ (NYSE: IONQ) and Rigetti Computing (NASDAQ: RGTI) are among the prominent players. IonQ uses ions to power its quantum machines while Rigetti employs the traditional superconducting qubits process. Both have seen impressive share price increases over the past year. IonQ stock is up over 400% through July 23 while Rigetti climbed more than 1,000% in that time. Is one a better investment in the nascent quantum computing field? Examining these businesses in more detail can help to arrive at an answer. Rigetti Computing's tried-and-true tech Rigetti uses a proven method of producing qubits. Qubits are a quantum device's equivalent to a classical computer's bit. But while bits represent a zero or one, the properties of quantum mechanics mean qubits can be both at the same time, enabling orders of magnitude faster processing speeds. Superconducting qubits offer several advantages. They can be manufactured using existing semiconductor chip processes, and can complete calculations faster than ion-based quantum machines. Rigetti hopes to gain greater commercialization with the latest version of its quantum computer, the Ankaa-3 system, which launched at the end of 2024. However, the technology isn't cheap. Superconducting qubits require special cryogenic equipment to keep temperatures colder than outer space. This is necessary for qubits to maintain stability long enough to perform calculations before they break down. As a result, the company exited the first quarter with an operating loss of $21.6 million on sales of $1.5 million. The loss is 30% greater than the previous year while Q1 revenue plunged 52% year over year. This combination of falling revenue and rising costs is unsustainable over the long run. That's why Rigetti executed a $350 million equity offering that helped it build up a stockpile of $575 million in cash, cash equivalents, and investments with no debt as of June 11. This cash hoard should sustain the company's operations in the short term, but it will need to produce revenue growth to build a sustainable business. IonQ's lofty ambition to remake the internet IonQ's ion-based method holds several advantages over superconducting qubits. Its tech can operate at room temperature, eschewing the need for cryogenic equipment. The technology also offers low error correction rates. Because qubits quickly break down, quantum computers are prone to calculation mistakes that limit their ability to scale. IonQ's reduced error rates make scalability a possibility. Consequently, the company aims to construct a quantum computing network, reminiscent of the infrastructure that underpins today's world wide web. It pursued several acquisitions to achieve its goal of building "the next generation of the internet," in the words of IonQ Chairman Peter Chapman. But like Rigetti, IonQ's costs are rising. It posted a Q1 operating loss of $75.7 million, an increase from 2024's $52.9 million, on revenue of $7.6 million. So it, too, is pursuing an equity offering to the tune of $1 billion. In addition, IonQ believes it can hit revenue of $75 million to $95 million in 2025. This would be a strong increase over 2024, when sales soared 95% year over year to $43.1 million. Making the choice between IonQ and Rigetti Computing stock Although Rigetti's superconducting qubits technology is well established in the quantum computing industry, IonQ's approach is producing higher sales. On top of that, another factor to consider is share price valuation. This can be assessed using the price-to-sales (P/S) ratio, a metric commonly used when companies are not profitable. The chart reveals Rigetti's P/S multiple has skyrocketed from where it was a year ago, and is far higher than IonQ's as well. This suggests Rigetti stock is overpriced, making IonQ the better value. That said, IonQ stock is not cheap, given it has a P/S ratio exceeding 200. While quantum computers hold the promise of revolutionizing the computing industry, whether IonQ or Rigetti's approach will win out in the end is far from certain. After all, quantum computing is still in its infancy. Its market size was just $4 billion in 2024, although industry estimates predict rapid growth to $72 billion by 2035. As of now, IonQ's 2024 sales success coupled with an outlook of 2025 revenue growth, and a far better valuation compared to Rigetti, make its stock the superior quantum computing investment between these two businesses. Ideally, wait for a dip in IonQ's share price, and for its Q2 results to validate it's on a trajectory to hit 2025 sales targets before deciding to pick up shares. Should you buy stock in IonQ right now? Before you buy stock in IonQ, consider this: The Motley Fool Stock Advisor analyst team just identified what they believe are the for investors to buy now… and IonQ wasn't one of them. The 10 stocks that made the cut could produce monster returns in the coming years. Consider when Netflix made this list on December 17, 2004... if you invested $1,000 at the time of our recommendation, you'd have $636,628!* Or when Nvidia made this list on April 15, 2005... if you invested $1,000 at the time of our recommendation, you'd have $1,063,471!* Now, it's worth noting Stock Advisor's total average return is 1,041% — a market-crushing outperformance compared to 183% for the S&P 500. Don't miss out on the latest top 10 list, available when you join Stock Advisor. See the 10 stocks » *Stock Advisor returns as of July 21, 2025 Robert Izquierdo has positions in IonQ. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy. Better Quantum Computing Stock: IonQ vs. Rigetti Computing was originally published by The Motley Fool Error in retrieving data Sign in to access your portfolio Error in retrieving data Error in retrieving data Error in retrieving data Error in retrieving data
Daily Mail
24-07-2025
- Entertainment
- Daily Mail
Glamorous Italian nuclear physicist hits back at sexist trolls after being bombarded with abuse for posting video of herself in low-cut dress
A leading Italian physicist has clapped back at online trolls who made sexist remarks after she shared a video of herself wearing a low-cut dress. Nuclear scientist and quantum mechanics expert Gabriella Greison, 51, posted a clip to her Instagram account as she prepared to travel for an academic event in Sicily. The scientist, who is based in Milan, was shown wearing a pale green dress with a low-cut neckline as she told her followers that she was going to be a guest of honour at a graduation ceremony in the University of Messina. But Greison's video, which has racked up thousands of views, drew sexist reactions as followers commented on her revealing outfit. 'Indecent clothing, vulgar, undignified,' one critic wrote. 'The inexorable advance of age pushes some women to shoot their last fireworks,' another said. A third commented: 'You're just an old maid who needs to show off, not having anything to say.' But Greison responded to her critics in an Instagram post, writing that 'there is no dress code for dignity'. 'If you're looking for decency in an inch of fabric, rather than in the content of words, I recommend an experiment: try using your brain and positioning yourself in the current year, with all the struggles that have been fought by those before me', she said. 'We're in world is burning, the glaciers are melting, artificial intelligence reads our you're upset that a woman talks about science with a beautiful cleavage? Are you serious?', she added. Greison went on to tell her critics: 'It's not the dress that bothered you. It's the fact that a woman can talk about quantum physics without remembering a man, and therefore without asking for permission. 'Let him get on stage, explain wave function and Schrödinger, and have boobs in the meantime. Oops.' She later appeared at the graduation ceremony in a strappy red dress which she jokingly said was 'even worse' than the first one. Despite the trolls, several Instagram users have defended the glamorous scientist and have expressed admiration for her response. One user commended the 'exceptional professor' and praised her for being a 'great example for young girls who still live [in] this bitter conflict between beauty and intelligence'. Another said: 'If anyone is outraged by this video, relax the Victorian era is over for a while, stay calm and live in today's reality.' 'Maximum respect, huge admiration and full support... Against the hardcore haters', a third wrote. Greison graduated from the University of Milan with a degree in nuclear physics. She previously worked at the research centre at the Ecole Polytechnique in Paris. She is currently the director of the first Festival of Physics in Italy and was included in Forbes Magazine's '100 successful women of 2024' list.
