physics | Ascension Lifestyle

11 Sep 2023
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Scientists may be on brink of discovering fifth force of nature

The tantalising theory that a fifth force of nature could exist has been given a boost thanks to unexpected wobbling by a subatomic particle, physicists have revealed.

According to current understanding, there are four fundamental forces in nature, three of which – the electromagnetic force and the strong and weak nuclear forces – are explained by the standard model of particle physics.

However, the model does not explain the other known fundamental force, gravity, or dark matter – a strange and mysterious substance thought to make up about 27% of the universe.

Now researchers have said there could be another, fifth, fundamental force of nature.

Dr Mitesh Patel, from Imperial College London, said: “We’re talking about a fifth force because we can’t necessarily explain the behaviour [in these experiments] with the four we know about.”

The data comes from experiments at the Fermilab US particle accelerator facility, which explored how subatomic particles called muons – similar to electrons but about 200 times heavier – move in a magnetic field.

Patel says the muons behave a bit like a child’s spinning top, in rotating around the axis of the magnetic field. However, as the muons move, they wobble. The frequency of that wobble can be predicted by the standard model.

But the experimental results from FermiLab do not appear to match those predictions.

Prof Jon Butterworth of University College London, who works on the Atlas experiment at the Large Hadron Collider (LHC) at Cern, said: “The wobbles are due to the way the muon interacts with a magnetic field. They can be calculated very precisely in the standard model but that calculation involves quantum loops, with known particles appearing in those loops.

“If the measurements don’t line up with the prediction, that could be a sign that there is some unknown particle appearing in the loops – which could, for example, be the carrier of a fifth force.”

The findings follow previous work from FermiLab that showed similar results.

But Patel said there was a “fly in the ointment”, noting that between the first results and the new data, uncertainty has increased around the theoretical prediction of the frequency.

That, he said, could shift the situation. “Maybe what they are seeing is standard scientific thinking – the so-called standard model,” Patel said.

There are other issues. Butterworth said: “If the discrepancy is confirmed, we will be sure there is something new and exciting but we won’t be sure exactly what it is.

“Ideally the discrepancy would inform new theoretical ideas that would lead to new predictions – for example, of how we might find the particle that carries the new force, if that’s what it is. The final confirmation would then be building an experiment to directly discover that particle.”

The experiments at Fermilab are not the only ones to suggest the possibility of a fifth force: work at the LHC has also produced tantalising findings, albeit with a different type of experiment looking at the rate at which muons and electrons are produced as certain particles decay.

But Patel, who worked on the LHC experiments, said those results were now less coherent.

“They are different experiments, measuring different things, and there may or may not be a connection,” he said.

Butterworth added that the unexpected frequency of the muons’ wobbles was one of the longest-standing and most significant discrepancies between a measurement and the standard model.

“The measurement is a great achievement, and very unlikely to be in error now,” he said. “So if the theory predictions get sorted out, this could indeed be the first confirmed evidence for a fifth force – or something else strange and beyond the standard model.”

Original article here

11 Aug 2023
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5 Amazing New Discoveries About Light

You might think that after centuries of studying light, we know pretty much everything about it. It’s true we’ve had breakthrough after breakthrough in using it, from illumination to communication, from examining the micro- and macro-universes to scanning our own bodies. We understand that light is an electromagnetic wave, thanks to James Clerk Maxwell, whose equations established that in 1865; and that it also appears as quantum packets of electromagnetic energy called photons, as Albert Einstein recognized in 1905. But the more we look into light, the more we see and the more we learn. The classical view of light as a wave still produces new science as light waves interact with artificial “metamaterials”; and we are still exploring light as a quantum particle. Both approaches provide ways to manipulate light that were once only science fiction. Here are five recent marvels.

Bending Light for Invisibility

The magical invisibility rings and cloaks featured in fantasy stories reflect the ancient human dream of hiding things and people from sight. Invisibility shows up in science fiction too, like Star Trek, where hostile Romulan spacecraft conceal themselves with a cloaking device. This uses an idea from relativity, that strongly distorted spacetime makes light curve around the spacecraft as if it didn’t exist.

Physicists don’t yet know how to do that, but the classical optics of light waves and light rays points to another solution. We see an object as it interacts with incoming light. In principle, an invisibility cloak could intercept those incoming rays and bend or refract them into itself so they travel inside the cloak and emerge along their original paths. An observer, seeing what looks like undisturbed light, would think nothing is there, just as flowing water smoothly splitting around a rock and then recombining gives no downstream indication of the rock. But to make light follow this complex path, the cloak needs to be made from a metamaterial.

Researchers first tested this idea in 2006 with a rigid metamaterial cloak, a hollow cylinder whose wall held thousands of small structures that made microwaves traverse suitable paths within the wall. Placed around an opaque metal object, the cloak made the object nearly completely vanish under microwave radiation. Since then, researchers have made small inanimate objects and a fish, a cat, and a hand vanish under ordinary visible light, but only as seen over a narrow angle of view. Others have developed a flexible cloak that wraps around a small object to make it vanish, but only at one wavelength. Science can’t yet make a cloak that completely hides a person in ordinary light; but invisibility research is thriving and we’re approaching Harry Potter’s wondrous cloak.

Light Pushes and Pulls Things

Like thrown rocks, photons carry momentum that they transfer to an object on impact. This radiation pressure is why sunlight pushes comet tails away from the sun, and why it can propel a spacecraft. In 2010, the Japan Aerospace Exploration Agency (JAXA) launched IKAROS (Interplanetary Kite-craft Accelerated by Radiation of the Sun, honoring Icarus who flew near the sun in myth). Its thin, tennis court-sized polymer sail gathered solar photons, which collectively exerted a small force that steadily accelerated IKAROS. Six months and 300 million miles later, it arrived on target near Venus without using any fuel for propulsion. Now JAXA and other space agencies are considering longer missions using bigger, more effective solar sails.

We’re approaching Harry Potter’s wondrous cloak.

Remarkably, a light source can also pull an object toward itself, against the direction that the light propagates. Physicists have shown that within a specially shaped laser beam, the forward push of photons on a particle is dominated by a backward force due to the particle’s own electromagnetic response. The effect is strong enough to pull a microscopic object like a biological cell backward toward the laser. In 2023, however, a related experiment showed that a low-power laser could pull a comparatively big macroscopic object, 0.2 inch x 0.1 inch. This is hardly a powerful sci-fi “tractor beam” that can reel in an entire spacecraft, but it could provide a new way to remotely sample the atmosphere on Earth and other planets, and phenomena like comet’s tails.

Ghost Imaging: Pictures in the Dark

Suppose you want to form an image of something like a living cell that could be changed or harmed by the light energy that illuminates it. Ghost imaging uses the phenomenon of photon entanglement to produce an excellent image of a barely illuminated object. Entangled photon pairs, which are formed by certain optical processes, are quantum-correlated, such that measuring the properties of one immediately reveals the properties of the other, no matter how distant.

In ghost imaging, one of each of a swarm of entangled photon pairs interacts with the object and encounters a detector that simply registers its arrival. A second beam of the corresponding entangled partners never touches the object but goes straight to a sensitive multi-pixel detector. Computer analysis of the correlations between the two detector results creates a high-quality image of the object, even with weak illumination. This approach has uses such as converting images covertly taken by invisible infrared light to visible images detected by a high-resolution camera; or obtaining good quality X-ray images from a patient exposed to a low, relatively safe X-ray dose.

Quantum Slits in Time

In the famous double-slit experiment, first done in 1801, a light beam splits as it passes through two narrow slits in an opaque barrier. On the far side, the beams spread and overlap to form a pattern of bright and dark areas on a screen, showing that light consists of waves that can interfere with each other. But a modern version of the experiment where just one photon at a time is aimed at the slits still produces a wave-like interference pattern. According to Richard Feynman, this striking, still unexplained example of wave-particle duality “has in it the heart of quantum mechanics … it contains the only mystery.”

Light was slowed to 38 mph, which a fit cyclist could match.

Now physicists have reproduced this experiment with slits in time rather than space. They used a thin film of indium tin oxide (ITO), which is transparent to infrared light but quickly becomes reflective within 10-15 sec when excited by a laser. In the experiment, the researchers shot infrared light at the ITO. When the ITO became a mirror for a short time, the reflected infrared light remained in its original form. But when the ITO mirror was very briefly turned on and off twice in rapid succession, the reflected infrared light showed definitively that it had interfered with itself as a result of passing through not one but two time portals or slits.

One observer has commented that this work could become a classic like the original double-slit experiment. By extending that into time rather than space, the research offers a new way to explore “the only mystery.” The work also shows the feasibility of using metamaterials like ITO to control light in optical systems and quantum computers at ultra-fast speeds.

Overtaking Light on a Bicycle

If there is one physics fact that people know, it’s that light is the fastest thing in the universe, traveling at 186,000 miles/sec in vacuum. The speed is reduced somewhat when light interacts with ordinary matter, dropping, for instance, to 124,000 miles/sec in optical fiber and plain glass. This is still fast enough to circle the Earth in a fraction of a second; and so it was big news in 1999 when Harvard researcher Lene Hau enormously slowed light to the human-scale speed of 38 mph, which a fit cyclist could match. This was accomplished in an exotic medium, a dense gas of sodium atoms cooled to nearly absolute zero. The result was a quantum medium called a Bose-Einstein condensate. Light interacts with this more strongly than with any ordinary medium and so it was hugely slowed. Later, Hau topped this achievement by bringing light to a screeching halt, then later recovering it and sending it on its way.

These results are breakthroughs in fundamental physics and could be useful as well, except for the need to work at temperatures near absolute zero. But since the original work, other researchers have slowed light in gases and solids at room temperature, making it possible to use slowed and stopped light in practical devices. These are currently being developed, for example, to synchronize signals in fiber optic networks and to store digital data in computers. Both applications are important steps toward developing advanced telecommunications networks and quantum computers based entirely on light rather than conventional electronic chips.

Original article here

18 Jun 2023
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Can We Time Travel? A Theoretical Physicist Provides Some Answers

Time travel makes regular appearances in popular culture, with innumerable time travel storylines in movies, television and literature. But it is a surprisingly old idea: one can argue that the Greek tragedy Oedipus Rex, written by Sophocles over 2,500 years ago, is the first time travel story.

But is time travel in fact possible? Given the popularity of the concept, this is a legitimate question. As a theoretical physicist, I find that there are several possible answers to this question, not all of which are contradictory.

The simplest answer is that time travel cannot be possible because if it was, we would already be doing it. One can argue that it is forbidden by the laws of physics, like the second law of thermodynamics or relativity. There are also technical challenges: it might be possible but would involve vast amounts of energy.

There is also the matter of time-travel paradoxes; we can — hypothetically — resolve these if free will is an illusion, if many worlds exist or if the past can only be witnessed but not experienced. Perhaps time travel is impossible simply because time must flow in a linear manner and we have no control over it, or perhaps time is an illusion and time travel is irrelevant.

Laws of Physics

Since Albert Einstein’s theory of relativity — which describes the nature of time, space and gravity — is our most profound theory of time, we would like to think that time travel is forbidden by relativity. Unfortunately, one of his colleagues from the Institute for Advanced Study, Kurt Gödel, invented a universe in which time travel was not just possible, but the past and future were inextricably tangled.

We can actually design time machines, but most of these (in principle) successful proposals require negative energy, or negative mass, which does not seem to exist in our universe. If you drop a tennis ball of negative mass, it will fall upwards. This argument is rather unsatisfactory, since it explains why we cannot time travel in practice only by involving another idea — that of negative energy or mass — that we do not really understand.

Mathematical physicist Frank Tipler conceptualized a time machine that does not involve negative mass, but requires more energy than exists in the universe.

Time travel also violates the second law of thermodynamics, which states that entropy or randomness must always increase. Time can only move in one direction — in other words, you cannot unscramble an egg. More specifically, by travelling into the past we are going from now (a high entropy state) into the past, which must have lower entropy.

This argument originated with the English cosmologist Arthur Eddington, and is at best incomplete. Perhaps it stops you travelling into the past, but it says nothing about time travel into the future. In practice, it is just as hard for me to travel to next Thursday as it is to travel to last Thursday.

Resolving Paradoxes

There is no doubt that if we could time travel freely, we run into the paradoxes. The best known is the “grandfather paradox”: one could hypothetically use a time machine to travel to the past and murder their grandfather before their father’s conception, thereby eliminating the possibility of their own birth. Logically, you cannot both exist and not exist.

Kurt Vonnegut’s anti-war novel Slaughterhouse-Five, published in 1969, describes how to evade the grandfather paradox. If free will simply does not exist, it is not possible to kill one’s grandfather in the past, since he was not killed in the past. The novel’s protagonist, Billy Pilgrim, can only travel to other points on his world line (the timeline he exists in), but not to any other point in space-time, so he could not even contemplate killing his grandfather.

The universe in Slaughterhouse-Five is consistent with everything we know. The second law of thermodynamics works perfectly well within it and there is no conflict with relativity. But it is inconsistent with some things we believe in, like free will — you can observe the past, like watching a movie, but you cannot interfere with the actions of people in it.

Could we allow for actual modifications of the past, so that we could go back and murder our grandfather — or Hitler? There are several multiverse theories that suppose that there are many timelines for different universes. This is also an old idea: in Charles Dickens’ A Christmas Carol, Ebeneezer Scrooge experiences two alternative timelines, one of which leads to a shameful death and the other to happiness.

Time Is a River

Roman emperor Marcus Aurelius wrote that:

Time is like a river made up of the events which happen, and a violent stream; for as soon as a thing has been seen, it is carried away, and another comes in its place, and this will be carried away too.

We can imagine that time does flow past every point in the universe, like a river around a rock. But it is difficult to make the idea precise. A flow is a rate of change — the flow of a river is the amount of water that passes a specific length in a given time. Hence if time is a flow, it is at the rate of one second per second, which is not a very useful insight.

Theoretical physicist Stephen Hawking suggested that a “chronology protection conjecture” must exist, an as-yet-unknown physical principle that forbids time travel. Hawking’s concept originates from the idea that we cannot know what goes on inside a black hole, because we cannot get information out of it. But this argument is redundant: we cannot time travel because we cannot time travel!

Researchers are investigating a more fundamental theory, where time and space “emerge” from something else. This is referred to as quantum gravity, but unfortunately it does not exist yet.

So is time travel possible? Probably not, but we don’t know for sure!

Original article here

11 Feb 2023
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Why More Physicists Are Starting to Think Space and Time Are ‘Illusions’

This past December, the physics Nobel Prize was awarded for the experimental confirmation of a quantum phenomenon known for more than 80 years: entanglement. As envisioned by Albert Einstein and his collaborators in 1935, quantum objects can be mysteriously correlated even if they are separated by large distances. But as weird as the phenomenon appears, why is such an old idea still worth the most prestigious prize in physics?

Coincidentally, just a few weeks before the new Nobel laureates were honored in Stockholm, a different team of distinguished scientists from Harvard, MIT, Caltech, Fermilab and Google reported that they had run a process on Google’s quantum computer that could be interpreted as a wormhole. Wormholes are tunnels through the universe that can work like a shortcut through space and time and are loved by science fiction fans, and although the tunnel realized in this recent experiment exists only in a 2-dimensional toy universe, it could constitute a breakthrough for future research at the forefront of physics.

But why is entanglement related to space and time? And how can it be important for future physics breakthroughs? Properly understood, entanglement implies that the universe is “monistic”, as philosophers call it, that on the most fundamental level, everything in the universe is part of a single, unified whole. It is a defining property of quantum mechanics that its underlying reality is described in terms of waves, and a monistic universe would require a universal function. Already decades ago, researchers such as Hugh Everett and Dieter Zeh showed how our daily-life reality can emerge out of such a universal quantum-mechanical description. But only now are researchers such as Leonard Susskind or Sean Carroll developing ideas on how this hidden quantum reality might explain not only matter but also the fabric of space and time.

Entanglement is much more than just another weird quantum phenomenon. It is the acting principle behind both why quantum mechanics merges the world into one and why we experience this fundamental unity as many separate objects. At the same time, entanglement is the reason why we seem to live in a classical reality. It is—quite literally—the glue and creator of worlds. Entanglement applies to objects comprising two or more components and describes what happens when the quantum principle that “everything that can happen actually happens” is applied to such composed objects. Accordingly, an entangled state is the superposition of all possible combinations that the components of a composed object can be in to produce the same overall result. It is again the wavy nature of the quantum domain that can help to illustrate how entanglement actually works.

Picture a perfectly calm, glassy sea on a windless day. Now ask yourself, how can such a plane be produced by overlaying two individual wave patterns? One possibility is that superimposing two completely flat surfaces results again in a completely level outcome. But another possibility that might produce a flat surface is if two identical wave patterns shifted by half an oscillation cycle were to be superimposed on one another, so that the wave crests of one pattern annihilate the wave troughs of the other one and vice versa. If we just observed the glassy ocean, regarding it as the result of two swells combined, there would be no way for us to find out about the patterns of the individual swells. What sounds perfectly ordinary when we talk about waves has the most bizarre consequences when applied to competing realities. If your neighbor told you she had two cats, one live cat and a dead one, this would imply that either the first cat or the second one is dead and that the remaining cat, respectively, is alive—it would be a strange and morbid way of describing one’s pets, and you may not know which one of them is the lucky one, but you would get the neighbor’s drift. Not so in the quantum world. In quantum mechanics, the very same statement implies that the two cats are merged in a superposition of cases, including the first cat being alive and the second one dead and the first cat being dead while the second one lives, but also possibilities where both cats are half alive and half dead, or the first cat is one-third alive, while the second feline adds the missing two-thirds of life. In a quantum pair of cats, the fates and conditions of the individual animals get dissolved entirely in the state of the whole. Likewise, in a quantum universe, there are no individual objects. All that exists is merged into a single “One.”

I’m almost certain that space and time are illusions. These are primitive notions that will be replaced by something more sophisticated.”

— Nathan Seiberg, Institute for Advanced Study

Quantum entanglement reveals to us a vast and entirely new territory to explore. It defines a new foundation of science and turns our quest for a theory of everything upside down—to build on quantum cosmology rather than on particle physics or string theory. But how realistic is it for physicists to pursue such an approach? Surprisingly, it is not just realistic—they are actually doing it already. Researchers at the forefront of quantum gravity have started to rethink space-time as a consequence of entanglement. An increasing number of scientists have come to ground their research in the nonseparability of the universe. Hopes are high that by following this approach they may finally come to grasp what space and time, deep down at the foundation, really are.

Whether space is stitched together by entanglement, physics is described by abstract objects beyond space and time or the space of possibilities represented by Everett’s universal wave function, or everything in the universe is traced back to a single quantum object—all these ideas share a distinct monistic flavor. At present it is hard to judge which of these ideas will inform the future of physics and which will eventually disappear. What’s interesting is that while originally ideas were often developed in the context of string theory, they seem to have outgrown string theory, and strings play no role anymore in the most recent research. A common thread now seems to be that space and time are not considered fundamental anymore. Contemporary physics doesn’t start with space and time to continue with things placed in this preexisting background. Instead, space and time themselves are considered products of a more fundamental projector reality. Nathan Seiberg, a leading string theorist at the Institute for Advanced Study at Princeton, New Jersey, is not alone in his sentiment when he states, “I’m almost certain that space and time are illusions. These are primitive notions that will be replaced by something more sophisticated.” Moreover, in most scenarios proposing emergent space-times, entanglement plays the fundamental role. As philosopher of science Rasmus Jaksland points out, this eventually implies that there are no individual objects in the universe anymore; that everything is connected with everything else: “Adopting entanglement as the world making relation comes at the price of giving up separability. But those who are ready to take this step should perhaps look to entanglement for the fundamental relation with which to constitute this world (and perhaps all the other possible ones).” Thus, when space and time disappear, a unified One emerges.

Conversely, from the perspective of quantum monism, such mind-boggling consequences of quantum gravity are not far off. Already in Einstein’s theory of general relativity, space is no static stage anymore; rather it is sourced by matter’s masses and energy. Much like the German philosopher Gottfried W. Leibniz’s view, it describes the relative order of things. If now, according to quantum monism, there is only one thing left, there is nothing left to arrange or order and eventually no longer a need for the concept of space on this most fundamental level of description. It is “the One,” a single quantum universe that gives rise to space, time, and matter.

“GR=QM,” Leonard Susskind claimed boldly in an open letter to researchers in quantum information science: general relativity is nothing but quantum mechanics—a hundred-year-old theory that has been applied extremely successfully to all sorts of things but never really entirely understood. As Sean Carroll has pointed out, “Maybe it was a mistake to quantize gravity, and space-time was lurking in quantum mechanics all along.” For the future, “rather than quantizing gravity, maybe we should try to gravitize quantum mechanics. Or, more accurately but less evocatively, ‘find gravity inside quantum mechanics,’” Carroll suggests on his blog. Indeed, it seems that if quantum mechanics had been taken seriously from the beginning, if it had been understood as a theory that isn’t happening in space and time but within a more fundamental projector reality, many of the dead ends in the exploration of quantum gravity could have been avoided. If we had approved the monistic implications of quantum mechanics—the heritage of a three-thousand-year-old philosophy that was embraced in antiquity, persecuted in the Middle Ages, revived in the Renaissance, and tampered with in Romanticism—as early as Everett and Zeh had pointed them out rather than sticking to the influential quantum pioneer Niels Bohr’s pragmatic interpretation that reduced quantum mechanics to a tool, we would be further on the way to demystifying the foundations of reality.

Original article here

22 Dec 2022
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Not just light: Everything is a wave, including you

In 1905, the 26-year-old Albert Einstein proposed something quite outrageous: that light could be both wave or particle. This idea is just as weird as it sounds. How could something be two things that are so different? A particle is small and confined to a tiny space, while a wave is something that spreads out. Particles hit one another and scatter about. Waves refract and diffract. They add on or cancel each other out in superpositions. These are very different behaviors.

Hidden in translation

The problem with this wave-particle duality is that language has issues accommodating both behaviors coming from the same object. After all, language is built of our experiences and emotions, of the things we see and feel. We do not directly see or feel photons. We probe into their nature with experimental set-ups, collecting information through monitors, counters, and the like.

The photons’ dual behavior emerges as a response to how we set up our experiment. If we have light passing through narrow slits, it will diffract like a wave. If it collides with electrons, it will scatter like a particle. So, in a way, it is our experiment, the question we are asking, that determines the physical nature of light. This introduces a new element into physics: the observer’s interaction with the observed. In more extreme interpretations, we could almost say that the intention of the experimenter determines the physical nature of what is being observed — that the mind determines physical reality. That’s really out there, but what we can say for sure is that light responds to the question we are asking in different ways. In a sense, light is both wave and particle, and it is neither.

This brings us to Bohr’s model of the atom, which we discussed a couple of weeks back. His model pins electrons orbiting the atomic nucleus to specific orbits. The electron can only be in one of these orbits, as if it is set on a train track. It can jump between orbits, but it cannot be in between them. How does that work, exactly? To Bohr, it was an open question. The answer came from a remarkable feat of physical intuition, and it sparked a revolution in our understanding of the world.

The wave nature of a baseball

In 1924, Louis de Broglie, a historian turned physicist, showed quite spectacularly that the electron’s step-like orbits in Bohr’s atomic model are easily understood if the electron is pictured as consisting of standing waves surrounding the nucleus. These are waves much like the ones we see when we shake a rope that is attached at the other end. In the case of the rope, the standing wave pattern appears due to the constructive and destructive interference between waves going and coming back along the rope. For the electron, the standing waves appear for the same reason, but now the electron wave closes on itself like an ouroboros, the mythic serpent that swallows its own tail. When we shake our rope more vigorously, the pattern of standing waves displays more peaks. An electron at higher orbits corresponds to a standing wave with more peaks.

With Einstein’s enthusiastic support, de Broglie boldly extended the notion of wave-particle duality from light to electrons and, by extension, to every moving material object. Not only light, but matter of any kind was associated with waves.

De Broglie offered a formula known as de Broglie wavelength to compute the wavelength of any matter with mass m moving at velocity v. He associated wavelength λ to m and v — and thus to momentum p = mv — according to the relation λ = h/p, where h is Planck’s constant. The formula can be refined for objects moving close to the speed of light.

As an example, a baseball moving at 70 km per hour has an associated de Broglie wavelength of about 22 billionths of a trillionth of a trillionth of a centimeter (or 2.2 x 10^-32 cm). Clearly, not much is waving there, and we are justified in picturing the baseball as a solid object. In contrast, an electron moving at one-tenth the speed of light has a wavelength about half the size of a hydrogen atom (more precisely, half the size of the most probable distance between an atomic nucleus and an electron at its lowest energy state).

While the wave nature of a moving baseball is irrelevant to understanding its behavior, the wave nature of the electron is essential to understand its behavior in atoms. The crucial point, though, is that everything waves. An electron, a baseball, and you.

Quantum biology

De Broglie’s remarkable idea has been confirmed in countless experiments. In college physics classes we demonstrate how electrons passing through a crystal diffract like waves, with superpositions creating dark and bright spots due to destructive and constructive interference. Anton Zeilinger, who shared the physics Nobel prize this year, has championed diffracting ever-larger objects, from the soccer-ball-shaped C₆₀ molecule (with 60 carbon atoms) to biological macromolecules.

The question is how life under such a diffraction experiment would behave at the quantum level. Quantum biology is a new frontier, one where the wave-particle duality plays a key role in the behavior of living beings. Can life survive quantum superposition? Can quantum physics tell us something about the nature of life?

Original article here

10 Feb 2022
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How The Physics of Resonance Shapes Reality

Almost any time physicists announce that they’ve discovered a new particle, whether it’s the Higgs boson or the recently bagged double-charm tetraquark, what they’ve actually spotted is a small bump rising from an otherwise smooth curve on a plot. Such a bump is the unmistakable signature of “resonance,” one of the most ubiquitous phenomena in nature.

Resonance underlies aspects of the world as diverse as music, nuclear fusion in dying stars, and even the very existence of subatomic particles. Here’s how the same effect manifests in such varied settings, from everyday life down to the smallest scales.

In its simplest form, resonance occurs when an object experiences an oscillating force that’s close to one of its “natural” frequencies, at which it easily oscillates. That objects have natural frequencies “is one of the bedrock properties of both math and the universe,” said Matt Strassler, a particle physicist affiliated with Harvard University who is writing a book about the Higgs boson. A playground swing is one familiar example: “Knock something like that around, and it will always pick out its resonant frequency automatically,” Strassler said. Or flick a wineglass and the rim will vibrate a few hundred times per second, producing a characteristic tone as the vibrations transfer to the surrounding air.

A system’s natural frequencies depend on its intrinsic properties: For a flute, for instance, they are the frequencies of sound waves that exactly fit inside its cylindrical geometry.

The Swiss mathematician Leonhard Euler solved the equation describing a system continuously driven near its resonant frequency in 1739. He found that the system exhibited “various and wonderful motions,” as he put it in a letter to fellow mathematician Johann Bernoulli, and that, when the system is driven precisely at the resonant frequency, the amplitude of the motion “increases continually and finally grows out to infinity.”

Driving a system too hard at the right frequency can have dramatic effects: A trained singer, for instance, can shatter a glass with a sustained note at its resonant frequency. A bridge resonating with the footsteps of marching soldiers can collapse. But more often, energy loss, which Euler’s analysis neglected, prevents the motion of a physical system from growing unchecked. If the singer sings the note quietly, vibrations in the glass will grow at first, but larger vibrations cause more energy to radiate outward as sound waves than before, so eventually a balance will be achieved that results in vibrations with constant amplitude.

Now suppose the singer starts with a low note and continuously glides up in pitch. As the singer sweeps past the frequency at which the wineglass resonates, the sound momentarily grows much louder. This enhancement arises because the sound waves arrive at the glass in sync with vibrations that are already present, just as pushing on a swing at the right time can amplify its initial motion. A plot of the sound amplitude as a function of frequency would trace out a curve with a pronounced bump around the resonant frequency, one that’s strikingly similar to the bumps heralding particle discoveries. In both cases, the bump’s width reflects how lossy the system is, indicating, for instance, how long a glass rings after it is struck once, or how long a particle exists before it decays.

The Higgs Boson Bump

But why do particles behave like humming wineglasses? At the turn of the 20th century, resonance was understood to be a property of vibrating and oscillating systems. Particles, which travel in straight lines and scatter like billiard balls, seemed far removed from this branch of physics.

The development of quantum mechanics showed otherwise. Experiments indicated that light, which had been thought of as an electromagnetic wave, sometimes behaves like a particle: a “photon,” which possesses an amount of energy proportional to the frequency of the associated wave. Meanwhile, matter particles like electrons sometimes exhibit wavelike behavior with the same relation between frequency and energy.

In 1925, inspired by this correspondence, the Austrian physicist Erwin Schrödinger derived an equation for the hydrogen atom whose solutions are waves oscillating at a set of natural frequencies, much like the solutions to equations governing the acoustics of wind instruments.

Each solution to Schrödinger’s equation represents a possible state of the atom’s orbiting electron. The electron can hop up to a higher-energy state by absorbing a photon whose frequency makes up the difference between the two states’ natural frequencies.

Such transitions are themselves a form of resonance: Just like a wine glass, an atom only absorbs energy from waves with specific frequencies, and it can also shed energy by emitting waves with those same frequencies. (When excited at precisely the right frequency, certain atoms will oscillate for more than 10 quadrillion cycles before releasing their energy as photons — extremely sharp atomic resonances that form the basis for the world’s most precise atomic clocks.)

Quantum theory revealed that the structure of atoms, no less than the structure of symphonies, is intimately tied to resonance. Electrons bound to atoms are a little like sound waves trapped inside flutes. As for the atomic nuclei, further advances in the 1930s showed that many kinds of atomic nuclei only exist in the universe today because of resonance. Resonant transitions are critical to the nuclear fusion reactions that transmute one type of atomic nucleus into another. The most celebrated of these nuclear resonances enables the fusion of three helium nuclei into one carbon nucleus. Without this, stars would not be capable of producing carbon or heavier elements, and life as we know it would not be possible.

But the roots of resonance in fundamental physics lie deeper. In the late 1920s physicists began to develop a powerful mathematical framework known as quantum field theory that remains the language of particle physics to this day. In quantum field theory, the universe’s truly elementary entities are fields that fill all space. Particles are localized, resonant excitations of these fields, vibrating like springs in an infinite mattress. The frequencies at which quantum fields prefer to vibrate stem from fundamental constants whose origins remain obscure; these frequencies in turn determine the masses of the corresponding particles. Blast the vacuum of empty space hard enough at the right frequency, and out will pop a bunch of particles.

In this sense, resonance is responsible for the very existence of particles. It has also increasingly become the workhorse of experimental particle physics. When measuring how often specific combinations of particles are produced in high-energy collisions, physicists see pronounced peaks in the detection rate as they vary the collision energy: new manifestations of the universal resonance curve. “As with the wineglass, you’re sweeping through a system that wants to resonate,” said Strassler. “You’ll make anything vibrate that can.”

In the 1950s and ’60s, physicists saw many more peaks than they had expected, and at first nobody knew quite what to make of them. Many of the bumps were very broad, suggesting the existence of particles that stuck around for barely more than a trillionth of a trillionth of a second. Unlike more familiar particles that can be detected directly, these newcomers could only be observed through the process of resonance.

Physicists later appreciated that these new ephemeral particles were fundamentally no different from protons and neutrons, save for their short lifetimes. Even so, short-lived particles are often simply referred to as “resonances” — a testament to a phenomenon that has played a surprisingly central role in expanding our understanding of the world.

Original article here.

30 Oct 2015
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The God Particle and Wisdom of the Ancients

Before Galileo Galilei and Sir Isaac Newton, the Lakota studied astronomy. Many indigenous peoples did. They were natural scientists. What sets indigenous “ethnoastronomy” apart from mainstream western astronomy is native peoples didn’t feel the need to separate their spiritual beliefs from other areas of their lives. The Lakota truly believed everything was interconnected. As a result, hard science observations and discoveries deciphered by Lakota over millennia are always intermingled with their spiritual beliefs, practices and ceremonies. In spite of frequent attempts by the western establishment to destroy such traditional knowledge, some has survived. Read more!