Category Archives: Quantum Physics
The strange link between the human mind and quantum physics
"I cannot define the real problem, therefore I suspect there's no real problem, but I'm not sure there's no real problem."
The American physicist Richard Feynman said this about the notorious puzzles and paradoxes of quantum mechanics, the theory physicists use to describe the tiniest objects in the Universe. But he might as well have been talking about the equally knotty problem of consciousness.
Some scientists think we already understand what consciousness is, or that it is a mere illusion. But many others feel we have not grasped where consciousness comes from at all.
The perennial puzzle of consciousness has even led some researchers to invoke quantum physics to explain it. That notion has always been met with skepticism, which is not surprising: it does not sound wise to explain one mystery with another. But such ideas are not obviously absurd, and neither are they arbitrary.
For one thing, the mind seemed, to the great discomfort of physicists, to force its way into early quantum theory. What's more, quantum computers are predicted to be capable of accomplishing things ordinary computers cannot, which reminds us of how our brains can achieve things that are still beyond artificial intelligence. "Quantum consciousness" is widely derided as mystical woo, but it just will not go away.
Quantum mechanics is the best theory we have for describing the world at the nuts-and-bolts level of atoms and subatomic particles. Perhaps the most renowned of its mysteries is the fact that the outcome of a quantum experiment can change depending on whether or not we choose to measure some property of the particles involved.
When this "observer effect" was first noticed by the early pioneers of quantum theory, they were deeply troubled. It seemed to undermine the basic assumption behind all science: that there is an objective world out there, irrespective of us. If the way the world behaves depends on how or if we look at it, what can "reality" really mean?
The most famous intrusion of the mind into quantum mechanics comes in the "double-slit experiment"
Some of those researchers felt forced to conclude that objectivity was an illusion, and that consciousness has to be allowed an active role in quantum theory. To others, that did not make sense. Surely, Albert Einstein once complained, the Moon does not exist only when we look at it!
Today some physicists suspect that, whether or not consciousness influences quantum mechanics, it might in fact arise because of it. They think that quantum theory might be needed to fully understand how the brain works.
Might it be that, just as quantum objects can apparently be in two places at once, so a quantum brain can hold onto two mutually-exclusive ideas at the same time?
These ideas are speculative, and it may turn out that quantum physics has no fundamental role either for or in the workings of the mind. But if nothing else, these possibilities show just how strangely quantum theory forces us to think.
The most famous intrusion of the mind into quantum mechanics comes in the "double-slit experiment". Imagine shining a beam of light at a screen that contains two closely-spaced parallel slits. Some of the light passes through the slits, whereupon it strikes another screen.
Light can be thought of as a kind of wave, and when waves emerge from two slits like this they can interfere with each other. If their peaks coincide, they reinforce each other, whereas if a peak and a trough coincide, they cancel out. This wave interference is called diffraction, and it produces a series of alternating bright and dark stripes on the back screen, where the light waves are either reinforced or cancelled out.
The implication seems to be that each particle passes simultaneously through both slits
This experiment was understood to be a characteristic of wave behaviour over 200 years ago, well before quantum theory existed.
The double slit experiment can also be performed with quantum particles like electrons; tiny charged particles that are components of atoms. In a counter-intuitive twist, these particles can behave like waves. That means they can undergo diffraction when a stream of them passes through the two slits, producing an interference pattern.
Now suppose that the quantum particles are sent through the slits one by one, and their arrival at the screen is likewise seen one by one. Now there is apparently nothing for each particle to interfere with along its route yet nevertheless the pattern of particle impacts that builds up over time reveals interference bands.
The implication seems to be that each particle passes simultaneously through both slits and interferes with itself. This combination of "both paths at once" is known as a superposition state.
But here is the really odd thing.
If we place a detector inside or just behind one slit, we can find out whether any given particle goes through it or not. In that case, however, the interference vanishes. Simply by observing a particle's path even if that observation should not disturb the particle's motion we change the outcome.
The physicist Pascual Jordan, who worked with quantum guru Niels Bohr in Copenhagen in the 1920s, put it like this: "observations not only disturb what has to be measured, they produce it We compel [a quantum particle] to assume a definite position." In other words, Jordan said, "we ourselves produce the results of measurements."
If that is so, objective reality seems to go out of the window.
And it gets even stranger.
If nature seems to be changing its behaviour depending on whether we "look" or not, we could try to trick it into showing its hand. To do so, we could measure which path a particle took through the double slits, but only after it has passed through them. By then, it ought to have "decided" whether to take one path or both.
The sheer act of noticing, rather than any physical disturbance caused by measuring, can cause the collapse
An experiment for doing this was proposed in the 1970s by the American physicist John Wheeler, and this "delayed choice" experiment was performed in the following decade. It uses clever techniques to make measurements on the paths of quantum particles (generally, particles of light, called photons) after they should have chosen whether to take one path or a superposition of two.
It turns out that, just as Bohr confidently predicted, it makes no difference whether we delay the measurement or not. As long as we measure the photon's path before its arrival at a detector is finally registered, we lose all interference.
It is as if nature "knows" not just if we are looking, but if we are planning to look.
Whenever, in these experiments, we discover the path of a quantum particle, its cloud of possible routes "collapses" into a single well-defined state. What's more, the delayed-choice experiment implies that the sheer act of noticing, rather than any physical disturbance caused by measuring, can cause the collapse. But does this mean that true collapse has only happened when the result of a measurement impinges on our consciousness?
It is hard to avoid the implication that consciousness and quantum mechanics are somehow linked
That possibility was admitted in the 1930s by the Hungarian physicist Eugene Wigner. "It follows that the quantum description of objects is influenced by impressions entering my consciousness," he wrote. "Solipsism may be logically consistent with present quantum mechanics."
Wheeler even entertained the thought that the presence of living beings, which are capable of "noticing", has transformed what was previously a multitude of possible quantum pasts into one concrete history. In this sense, Wheeler said, we become participants in the evolution of the Universe since its very beginning. In his words, we live in a "participatory universe."
To this day, physicists do not agree on the best way to interpret these quantum experiments, and to some extent what you make of them is (at the moment) up to you. But one way or another, it is hard to avoid the implication that consciousness and quantum mechanics are somehow linked.
Beginning in the 1980s, the British physicist Roger Penrose suggested that the link might work in the other direction. Whether or not consciousness can affect quantum mechanics, he said, perhaps quantum mechanics is involved in consciousness.
What if, Penrose asked, there are molecular structures in our brains that are able to alter their state in response to a single quantum event. Could not these structures then adopt a superposition state, just like the particles in the double slit experiment? And might those quantum superpositions then show up in the ways neurons are triggered to communicate via electrical signals?
Maybe, says Penrose, our ability to sustain seemingly incompatible mental states is no quirk of perception, but a real quantum effect.
Perhaps quantum mechanics is involved in consciousness
After all, the human brain seems able to handle cognitive processes that still far exceed the capabilities of digital computers. Perhaps we can even carry out computational tasks that are impossible on ordinary computers, which use classical digital logic.
Penrose first proposed that quantum effects feature in human cognition in his 1989 book The Emperor's New Mind. The idea is called Orch-OR, which is short for "orchestrated objective reduction". The phrase "objective reduction" means that, as Penrose believes, the collapse of quantum interference and superposition is a real, physical process, like the bursting of a bubble.
Orch-OR draws on Penrose's suggestion that gravity is responsible for the fact that everyday objects, such as chairs and planets, do not display quantum effects. Penrose believes that quantum superpositions become impossible for objects much larger than atoms, because their gravitational effects would then force two incompatible versions of space-time to coexist.
Penrose developed this idea further with American physician Stuart Hameroff. In his 1994 book Shadows of the Mind, he suggested that the structures involved in this quantum cognition might be protein strands called microtubules. These are found in most of our cells, including the neurons in our brains. Penrose and Hameroff argue that vibrations of microtubules can adopt a quantum superposition.
But there is no evidence that such a thing is remotely feasible.
It has been suggested that the idea of quantum superpositions in microtubules is supported by experiments described in 2013, but in fact those studies made no mention of quantum effects.
Besides, most researchers think that the Orch-OR idea was ruled out by a study published in 2000. Physicist Max Tegmark calculated that quantum superpositions of the molecules involved in neural signaling could not survive for even a fraction of the time needed for such a signal to get anywhere.
Other researchers have found evidence for quantum effects in living beings
Quantum effects such as superposition are easily destroyed, because of a process called decoherence. This is caused by the interactions of a quantum object with its surrounding environment, through which the "quantumness" leaks away.
Decoherence is expected to be extremely rapid in warm and wet environments like living cells.
Nerve signals are electrical pulses, caused by the passage of electrically-charged atoms across the walls of nerve cells. If one of these atoms was in a superposition and then collided with a neuron, Tegmark showed that the superposition should decay in less than one billion billionth of a second. It takes at least ten thousand trillion times as long for a neuron to discharge a signal.
As a result, ideas about quantum effects in the brain are viewed with great skepticism.
However, Penrose is unmoved by those arguments and stands by the Orch-OR hypothesis. And despite Tegmark's prediction of ultra-fast decoherence in cells, other researchers have found evidence for quantum effects in living beings. Some argue that quantum mechanics is harnessed by migratory birds that use magnetic navigation, and by green plants when they use sunlight to make sugars in photosynthesis.
Besides, the idea that the brain might employ quantum tricks shows no sign of going away. For there is now another, quite different argument for it.
In a study published in 2015, physicist Matthew Fisher of the University of California at Santa Barbara argued that the brain might contain molecules capable of sustaining more robust quantum superpositions. Specifically, he thinks that the nuclei of phosphorus atoms may have this ability.
Phosphorus atoms are everywhere in living cells. They often take the form of phosphate ions, in which one phosphorus atom joins up with four oxygen atoms.
Such ions are the basic unit of energy within cells. Much of the cell's energy is stored in molecules called ATP, which contain a string of three phosphate groups joined to an organic molecule. When one of the phosphates is cut free, energy is released for the cell to use.
Cells have molecular machinery for assembling phosphate ions into groups and cleaving them off again. Fisher suggested a scheme in which two phosphate ions might be placed in a special kind of superposition called an "entangled state".
Phosphorus spins could resist decoherence for a day or so, even in living cells
The phosphorus nuclei have a quantum property called spin, which makes them rather like little magnets with poles pointing in particular directions. In an entangled state, the spin of one phosphorus nucleus depends on that of the other.
Put another way, entangled states are really superposition states involving more than one quantum particle.
Fisher says that the quantum-mechanical behaviour of these nuclear spins could plausibly resist decoherence on human timescales. He agrees with Tegmark that quantum vibrations, like those postulated by Penrose and Hameroff, will be strongly affected by their surroundings "and will decohere almost immediately". But nuclear spins do not interact very strongly with their surroundings.
All the same, quantum behaviour in the phosphorus nuclear spins would have to be "protected" from decoherence.
This might happen, Fisher says, if the phosphorus atoms are incorporated into larger objects called "Posner molecules". These are clusters of six phosphate ions, combined with nine calcium ions. There is some evidence that they can exist in living cells, though this is currently far from conclusive.
I decided... to explore how on earth the lithium ion could have such a dramatic effect in treating mental conditions
In Posner molecules, Fisher argues, phosphorus spins could resist decoherence for a day or so, even in living cells. That means they could influence how the brain works.
The idea is that Posner molecules can be swallowed up by neurons. Once inside, the Posner molecules could trigger the firing of a signal to another neuron, by falling apart and releasing their calcium ions.
Because of entanglement in Posner molecules, two such signals might thus in turn become entangled: a kind of quantum superposition of a "thought", you might say. "If quantum processing with nuclear spins is in fact present in the brain, it would be an extremely common occurrence, happening pretty much all the time," Fisher says.
He first got this idea when he started thinking about mental illness.
"My entry into the biochemistry of the brain started when I decided three or four years ago to explore how on earth the lithium ion could have such a dramatic effect in treating mental conditions," Fisher says.
At this point, Fisher's proposal is no more than an intriguing idea
Lithium drugs are widely used for treating bipolar disorder. They work, but nobody really knows how.
"I wasn't looking for a quantum explanation," Fisher says. But then he came across a paper reporting that lithium drugs had different effects on the behaviour of rats, depending on what form or "isotope" of lithium was used.
On the face of it, that was extremely puzzling. In chemical terms, different isotopes behave almost identically, so if the lithium worked like a conventional drug the isotopes should all have had the same effect.
But Fisher realised that the nuclei of the atoms of different lithium isotopes can have different spins. This quantum property might affect the way lithium drugs act. For example, if lithium substitutes for calcium in Posner molecules, the lithium spins might "feel" and influence those of phosphorus atoms, and so interfere with their entanglement.
We do not even know what consciousness is
If this is true, it would help to explain why lithium can treat bipolar disorder.
At this point, Fisher's proposal is no more than an intriguing idea. But there are several ways in which its plausibility can be tested, starting with the idea that phosphorus spins in Posner molecules can keep their quantum coherence for long periods. That is what Fisher aims to do next.
All the same, he is wary of being associated with the earlier ideas about "quantum consciousness", which he sees as highly speculative at best.
Physicists are not terribly comfortable with finding themselves inside their theories. Most hope that consciousness and the brain can be kept out of quantum theory, and perhaps vice versa. After all, we do not even know what consciousness is, let alone have a theory to describe it.
We all know what red is like, but we have no way to communicate the sensation
It does not help that there is now a New Age cottage industry devoted to notions of "quantum consciousness", claiming that quantum mechanics offers plausible rationales for such things as telepathy and telekinesis.
As a result, physicists are often embarrassed to even mention the words "quantum" and "consciousness" in the same sentence.
But setting that aside, the idea has a long history. Ever since the "observer effect" and the mind first insinuated themselves into quantum theory in the early days, it has been devilishly hard to kick them out. A few researchers think we might never manage to do so.
In 2016, Adrian Kent of the University of Cambridge in the UK, one of the most respected "quantum philosophers", speculated that consciousness might alter the behaviour of quantum systems in subtle but detectable ways.
Kent is very cautious about this idea. "There is no compelling reason of principle to believe that quantum theory is the right theory in which to try to formulate a theory of consciousness, or that the problems of quantum theory must have anything to do with the problem of consciousness," he admits.
Every line of thought on the relationship of consciousness to physics runs into deep trouble
But he says that it is hard to see how a description of consciousness based purely on pre-quantum physics can account for all the features it seems to have.
One particularly puzzling question is how our conscious minds can experience unique sensations, such as the colour red or the smell of frying bacon. With the exception of people with visual impairments, we all know what red is like, but we have no way to communicate the sensation and there is nothing in physics that tells us what it should be like.
Sensations like this are called "qualia". We perceive them as unified properties of the outside world, but in fact they are products of our consciousness and that is hard to explain. Indeed, in 1995 philosopher David Chalmers dubbed it "the hard problem" of consciousness.
"Every line of thought on the relationship of consciousness to physics runs into deep trouble," says Kent.
This has prompted him to suggest that "we could make some progress on understanding the problem of the evolution of consciousness if we supposed that consciousnesses alters (albeit perhaps very slightly and subtly) quantum probabilities."
"Quantum consciousness" is widely derided as mystical woo, but it just will not go away
In other words, the mind could genuinely affect the outcomes of measurements.
It does not, in this view, exactly determine "what is real". But it might affect the chance that each of the possible actualities permitted by quantum mechanics is the one we do in fact observe, in a way that quantum theory itself cannot predict. Kent says that we might look for such effects experimentally.
He even bravely estimates the chances of finding them. "I would give credence of perhaps 15% that something specifically to do with consciousness causes deviations from quantum theory, with perhaps 3% credence that this will be experimentally detectable within the next 50 years," he says.
If that happens, it would transform our ideas about both physics and the mind. That seems a chance worth exploring.
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Registration Open for Inaugural IEEE International Conference on Quantum Computing and Engineering (QCE20) – thepress.net
LOS ALAMITOS, Calif., May 14, 2020 /PRNewswire/ --Registration is now open for the inaugural IEEE International Conference on Quantum Computing and Engineering (QCE20), a multidisciplinary event focusing on quantum technology, research, development, and training. QCE20, also known as IEEE Quantum Week, will deliver a series of world-class keynotes, workforce-building tutorials, community-building workshops, and technical paper presentations and posters on October 12-16 in Denver, Colorado.
"We're thrilled to open registration for the inaugural IEEE Quantum Week, founded by the IEEE Future Directions Initiative and supported by multiple IEEE Societies and organizational units," said Hausi Mller, QCE20 general chair and co-chair of the IEEE Quantum Initiative."Our initial goal is to address the current landscape of quantum technologies, identify challenges and opportunities, and engage the quantum community. With our current Quantum Week program, we're well on track to deliver a first-rate quantum computing and engineering event."
QCE20's keynote speakersinclude the following quantum groundbreakers and leaders:
The week-long QCE20 tutorials program features 15 tutorials by leading experts aimed squarely at workforce development and training considerations. The tutorials are ideally suited to develop quantum champions for industry, academia, and government and to build expertise for emerging quantum ecosystems.
Throughout the week, 19 QCE20 workshopsprovide forums for group discussions on topics in quantum research, practice, education, and applications. The exciting workshops provide unique opportunities to share and discuss quantum computing and engineering ideas, research agendas, roadmaps, and applications.
The deadline for submitting technical papers to the eight technical paper tracks is May 22. Papers accepted by QCE20 will be submitted to the IEEE Xplore Digital Library. The best papers will be invited to the journalsIEEE Transactions on Quantum Engineering(TQE)andACM Transactions on Quantum Computing(TQC).
QCE20 provides attendees a unique opportunity to discuss challenges and opportunities with quantum researchers, scientists, engineers, entrepreneurs, developers, students, practitioners, educators, programmers, and newcomers. QCE20 is co-sponsored by the IEEE Computer Society, IEEE Communications Society, IEEE Council on Superconductivity,IEEE Electronics Packaging Society (EPS), IEEE Future Directions Quantum Initiative, IEEE Photonics Society, and IEEETechnology and Engineering Management Society (TEMS).
Register to be a part of the highly anticipated inaugural IEEE Quantum Week 2020. Visit qce.quantum.ieee.org for event news and all program details, including sponsorship and exhibitor opportunities.
About the IEEE Computer SocietyThe IEEE Computer Society is the world's home for computer science, engineering, and technology. A global leader in providing access to computer science research, analysis, and information, the IEEE Computer Society offers a comprehensive array of unmatched products, services, and opportunities for individuals at all stages of their professional career. Known as the premier organization that empowers the people who drive technology, the IEEE Computer Society offers international conferences, peer-reviewed publications, a unique digital library, and training programs. Visit http://www.computer.orgfor more information.
About the IEEE Communications Society The IEEE Communications Societypromotes technological innovation and fosters creation and sharing of information among the global technical community. The Society provides services to members for their technical and professional advancement and forums for technical exchanges among professionals in academia, industry, and public institutions.
About the IEEE Council on SuperconductivityThe IEEE Council on Superconductivityand its activities and programs cover the science and technology of superconductors and their applications, including materials and their applications for electronics, magnetics, and power systems, where the superconductor properties are central to the application.
About the IEEE Electronics Packaging SocietyThe IEEE Electronics Packaging Societyis the leading international forum for scientists and engineers engaged in the research, design, and development of revolutionary advances in microsystems packaging and manufacturing.
About the IEEE Future Directions Quantum InitiativeIEEE Quantumis an IEEE Future Directions initiative launched in 2019 that serves as IEEE's leading community for all projects and activities on quantum technologies. IEEE Quantum is supported by leadership and representation across IEEE Societies and OUs. The initiative addresses the current landscape of quantum technologies, identifies challenges and opportunities, leverages and collaborates with existing initiatives, and engages the quantum community at large.
About the IEEE Photonics SocietyTheIEEE Photonics Societyforms the hub of a vibrant technical community of more than 100,000 professionals dedicated to transforming breakthroughs in quantum physics into the devices, systems, and products to revolutionize our daily lives. From ubiquitous and inexpensive global communications via fiber optics, to lasers for medical and other applications, to flat-screen displays, to photovoltaic devices for solar energy, to LEDs for energy-efficient illumination, there are myriad examples of the Society's impact on the world around us.
About the IEEE Technology and Engineering Management SocietyIEEE TEMSencompasses the management sciences and practices required for defining, implementing, and managing engineering and technology.
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Exploring the quantum field, from the sun’s core to the Big Bang – MIT News
How do protons fuse to power the sun? What happens to neutrinos inside a collapsing star after a supernova? How did atomic nuclei form from protons and neutrons in the first few minutes after the Big Bang?
Simulating these mysterious processes requires some extremely complex calculations, sophisticated algorithms, and a vast amount of supercomputing power.
Theoretical physicist William Detmold marshals these tools to look into the quantum realm. Improved calculations of these processes enable us to learn about fundamental properties of the universe, he says. Of the visible universe, most mass is made of protons. Understanding the structure of the proton and its properties seems pretty important to me.
Researchers at the Large Hadron Collider (LHC), the worlds largest particle accelerator, investigate those properties by smashing particles together and poring over the subatomic wreckage for clues to what makes up and binds together matter.
Detmold, an associate professor in the Department of Physics and a member of the Center for Theoretical Physics and the Laboratory for Nuclear Science, starts instead from first principles namely, the theory of the Standard Model of particle physics.
The Standard Model describes three of the four fundamental forces of particle physics (with the exception of gravity) and all of the known subatomic particles.
The theory has succeeded in predicting the results of experiments time and time again, including, perhaps most famously, the 2011 confirmation by LHC researchers of the existence of the Higgs boson.
A core focus of Detmolds research is on confronting experimental data from experiments such as the LHC. After devising calculations, running them on multiple supercomputers, and sifting through the enormous quantity of statistics they crank out a process that can take from six months to several years Detmold and his team then take all that data and do a lot of analysis to extract key physics quantities for example, the mass of the proton, as a numerical value with an uncertainty range.
My driving concern in this regard is how will this analysis impact experimental results, Detmold says. In some cases, we do these calculations in order to interpret experiments done at the LHC, and ask: Is the Standard Model describing whats going on there?
Detmold has made important advances in solving the complex equations of quantum chromodynamics (QCD), a quantum field theory that describes the strong interactions inside of a proton, between quarks (the smallest known constituent of matter) and gluons (the forces that bind them together).
He has performed some of the first QCD calculations of certain particle decays reactions. They have, for the most part, aligned very closely with results from the LHC.
There are no really stark discrepancies between the Standard Model and LHC results, but there are some interesting tensions, he says. My work has been looking at some of those tensions.
Inspired to ask questions
Detmolds interest in quantum physics dates to his schoolboy days, growing up in Adelaide, Australia. I remember reading a bunch of popular science books as a young kid, he recalls, and being very intrigued about quarks, gluons, and other fundamental particles, and wanting to get into the mathematical tools to work with them.
He would go on to earn both his bachelors degree and PhD from the University of Adelaide. As an undergraduate studying mathematics, he encountered a professor who opened his eyes to the mysteries of quantum mechanics. It was probably the most exciting class Ive had. And I get to teach that now.
Hes been teaching that introductory course on quantum mechanics at MIT for a few years now, and he has become adept at spotting those students who are similarly seized by the subject. In every class there are students you can see the enthusiasm dripping off the page as they write their problem sets. Its exciting to interact with them.
While he cant always bring the full complexity of his research into those conversations, he tries to infuse them with the spirit of his enterprise: how to ask the questions that might yield new insights into the deep structures of the universe.
You can frame things in ways to inspire students to go into research and push themselves to learn more, he says. A lot of teaching is about motivating students to go and find out more themselves, not just information transmission. And hopefully I inspire my students the way my professor inspired me.
He adds: With all of us stuck at home or in remote locations, Im not sure that anyone is feeling particularly inspired right now, but this pandemic will eventually end, and sometimes getting lost in the intricacies of Maxwells equations gives a nice break from what is going on in the world.
Enhancing experiments
When he isnt teaching or analyzing supercomputer data, Detmold is often helping to plan better experiments.
The Electron-Ion Collider, a facility planned for construction over the next decade at Brookhaven National Lab on Long Island, aims to advance understanding of the internal structure of the proton. Some of Detmolds calculations are aimed at providing a qualitative picture of the structure of gluons inside the proton, to help the projects designers know what to look for, in terms of orders of magnitude for detecting certain quantities.
We can make predictions for what well be seeing if you design it in a certain way, he says.
Detmold has also become something of an expert at orchestrating complex supercomputing projects. That entails figuring out how to run a huge number of calculations in an efficient way, given the limited availability of supercomputing power and time.
He and his lab members have developed algorithms and software infrastructure to run these calculations on massive supercomputers, some of which have different types of processing units that make data management complicated. Its a research project in its own right, how to perform those calculations in a way thats efficient.
Indeed, Detmold spends time working on how improve methods for getting to the answer. New algorithms, he says, are a key to advancing computation to tackle new problems, calculating nuclear structures and reactions in the context of the Standard Model.
Lets say theres a quantity we want to compute, but with the tools we have at the moment it takes 10,000 years of running a massive supercomputer, he says. Coming up with a new way to calculate something that actually makes it possible to do thats exciting.
Inspiring interest in the unknown
But fundamental mysteries are still at the center of Detmolds work. As quarks and gluons get farther apart from each other, the strength of their interactions increases. To understand whats happening in these low-energy states, he has advanced the use of a computational technique known as lattice quantum chromodynamics (LQCD), which places the quantum fields of the quarks and gluons on a discretized grid of points to represent space-time.
In 2017, Detmold and colleagues made the first-ever LQCD calculations of the rate of proton-proton fusion the process by which two protons fuse together to form a deuteron.
This process kicks off the nuclear reactions that power the sun. Its also exceedingly difficult to study through experiments. If you try to smash together two protons, their electric charges mean they dont want to be near each other, says Detmold.
It shows where this field can go, he says of his teams breakthrough. Its one of the simplest nuclear reactions, but it opens the doorway to saying we can address these directly from the Standard Model. Were trying to build upon this work and calculate related reactions.
Another recent project involved using LQCD to study the formation of nuclei in the universe its earliest moments. As well as looking at these processes for the actual universe, hes performed computations that change certain parameters the masses of quarks and how strongly they interact in order to predict how the reactions of Big Bang nucleosynthesis might have happened and how much they might have affected the evolution of the universe.
These calculations can tell you how likely it is to end up producing universes like the one we see, Detmold says.
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Exploring the quantum field, from the sun's core to the Big Bang - MIT News
The Era of Anomalies – Physics
Anomalies may be regarded with skepticism, but they often open the door for theorists to play. One of the most promising sandboxes for model builders has been anomalies in B physicsinteractions involving B mesons, which are particles composed of a bottom quark or antiquark plus another type of quark. A coterie of results from LHCb at CERN, Belle in Japan, and Babar in the US, point to potential problems with the standard model predictions for some rare B meson decays.
Alone, each notable B physics result is only a few-sigma discrepancy. But taken together, the aggregate of the results isdepending on whom you aska 5- to 7-sigma deviation from the standard model estimates. Ive worked in the field for a long time, says Isidori. Weve seen a lot of anomalies here and there popping up and going back, but this time I think its different . For the first time, its not just one thing that doesnt fit with the other, but its a coherent set of things.
If the anomalies are a hint of something real, the simplest explanation is a new particle called the Z, a partner to the Z boson that differs only slightly in its interactions with other particles (see Synopsis: Closing in on the Z' Boson). Isidori is not a big fan of the Z; he prefers a leptoquark. This hypothetical particle would form a bridge between leptons (electrons, muons, and taus) and quarks (see Viewpoint: A Challenge to Lepton Universality).
Many theorists attempt to link anomalies together in models. For example, a new anomaly from KOTO, an experiment at JPARC in Japan, measuring the lifetime of neutral kaons, has piqued theorists attention. Jia Liu, a theoretical physicist at the University of Chicago, wrote a paper that proposed a light, Higgs-like particle, or scalar boson, that would interact with muons and would explain both the KOTO anomaly and the muon anomaly. While theorists like finding one explanation for multiple anomalies, its often difficult to match all the data. Attempts to find a combined explanation for both the B physics and muon anomalies have mostly fallen flat. Two anomalies to deal with is my limit, because it is not easy, Liu says jokingly.
The best models, according to theorists, are those that fit the data naturally, without too much finagling. Neutrinos have been the focus of several recent anomalies, such as unexpected oscillations in the flavors of neutrinos observed by MiniBooNE at Fermilab in 2018 (see Viewpoint: The Plot Thickens for a Fourth Neutrino). To explain neutrino anomalies, the most straightforward thing to do is to introduce one new neutrino says Mona Dentler, a neutrino physicist at the University of Gttingen, Germany. The trouble is that this addition, called a sterile neutrino, is a possible dark matter candidate, which means it must agree with cosmological data. Constraints like this can require highly tailored solutions from theorists. You normally have to kind of stand on your head and add a bunch of different epicycles to somehow make the data fit your models, says Patrick Meade, a theorist at Stony Brook University, New York.
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Exploring new tools in string theory – Space.com
String theorists are shifting focus to solve some rather sticky problems in physics.
Over the past few years, string theory has been less about trying to find a unifying description of all forces and matter in the universe, and more about exploring the AdS/CFT correspondence, a potential link between the tools and methods developed in the string community and some strange physics problems.
While it doesn't have a particularly catchy name, the AdS/CFT correspondence, it is a potentially powerful (but so for unproven) tool to solve complex riddles.
Related:Putting string theory to the test
The "AdS" in the AdS/CFT correspondence stands for "anti-de Sitter," which doesn't explain much at first glance. The name was inspired by Willem de Sitter, a physicist and mathematician who played around with Einstein's theory of general relativity shortly after it was published in 1917. De Sitter experimented with the idea of different kinds of theoretical universes, filling them up with various substances and figuring out how they would evolve.
His namesake, the "de Sitter universe," represents a theoretical cosmos completely devoid of matter but filled with a positive cosmological constant. While this isn't how our universe actually is, as the universe continues to age it will look more and more like de Sitter's vision.
The anti-de Sitter universe is the exact opposite: a completely empty cosmos with a negative cosmological constant, which is quite unlike what we see in our real universe.
But, while this strange theoretical "anti" universe isn't real, it's still a handy mathematical playground for string theory.
String theory itself requires 10 dimensions to be complete (6 of which are tiny and curled up to microscopic proportions), but versions of it can be cast into only 5 dimensions in an anti-de Sitter spacetime, and, while useful for our universe, can still function.
The other side of the AdS/CFT correspondence, CFT, stands for conformal field theory. Field theories are the bread and butter of our modern understanding of the quantum world; they are what happens when you marry quantum mechanics with special relativity and are used to explain three of the four forces of nature. For example, electromagnetism is described by the field theory called quantum electrodynamics (QED), and the strong nuclear force by the field theory called quantum chromodynamics (QCD).
But there's an extra word there: conformal. But before we get to conformal, I want to quickly talk about something else: scale invariance (trust me, this will make sense in a minute). A field theory is said to be scale invariant if the results don't change if the strength of interactions are varied. For example, you would have a scale invariant engine if you got the same efficiency no matter what kind of fuel you put in.
In strict mathematical terms, a conformal field theory is just a certain special case of scale invariant field theory, but almost all the time when physicists say conformal, they really mean scale invariant. So in your head every time you read or hear conformal field theory you can just replace it with scale invariant field theory.
Our universe is, by and large, decidedly not scale invariant. The forces of nature do change their character with different energy scales and interaction strengths some forces even merge together at high energies. Scale invariance, as beautiful as it is mathematically, simply doesn't seem to be preferred by nature.
Related:The history and structure of the universe (infographic)
So, on one side of the AdS/CFT correspondence, you have a universe that doesn't look like ours, and on the other, you have mathematical theory that doesn't apply to most situations. So what's the big deal?
The big deal is that over twenty years ago, physicists and mathematicians found a surprising link between string theories written in a five-dimensional anti-de Sitter spacetime and conformal field theories written on the four-dimensional boundary of that spacetime. This correspondence so far unproven, but if there is a connection, it could have far-reaching consequences.
There are a lot of tools and tricks in the language of string theory, so if you're facing a thorny physics problem that can be written in terms of a conformal field theory (it's not common, but it does happen occasionally), you can cast it in terms of the 5d string theory and apply those tools to try to crack it.
Additionally, if you're trying to solve string theory problems (like, for example, the unification of gravity with other forces of nature), you can translate your problem into terms of a conformal field theory and use the tried-and-true techniques in that language to try to crack it.
Most work in this arena has been with trying to use the methods of string theory to solve real-world problems, like what happens to the information that's fallen into a black hole and the nature of high-energy states of matter.
Paul M. Sutteris an astrophysicist at SUNY Stony Brook and the Flatiron Institute, host of Ask a Spaceman and Space Radio, and author of Your Place in the Universe.
Learn more by listening to the episode "Is String Theory Worth It? (Part 7: A Correspondence from a Dear Friend)" on the Ask A Spaceman podcast, available oniTunesand on the Web athttp://www.askaspaceman.com. Thanks to John C., Zachary H., @edit_room, Matthew Y., Christopher L., Krizna W., Sayan P., Neha S., Zachary H., Joyce S., Mauricio M., @shrenicshah, Panos T., Dhruv R., Maria A., Ter B., oiSnowy, Evan T., Dan M., Jon T., @twblanchard, Aurie, Christopher M., @unplugged_wire, Giacomo S., Gully F. for the questions that led to this piece! Ask your own question on Twitter using #AskASpaceman or by following Paul @PaulMattSutter and facebook.com/PaulMattSutter.
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What part of ‘public’ does PSC not get? – The Bozeman Daily Chronicle
Several state news organizations have asked for what are clearly public documents from the state Public Service Commission. The commissions response? It has filed a lawsuit against those news organizations.
This represents a troubling pattern of behavior on the part of public agencies. The agencies claim they sue in order to get the courts to tell them what documents they are required to turn over. But this action forces anyone who makes a request for public documents not just media organizations to retain legal counsel, often at considerable expense.
The case in point involves emails sent and received by one commissioner, Roger Koopman. Koopman has been embroiled in internal disputes within the all-Republican commission. And some of the emails in question were leaked to a right-wing media website that posted them online. That prompted other news organizations the Billings Gazette, Yellowstone Public Radio and the Great Falls Tribune to request all the emails associated with the controversy.
This isnt quantum physics. The courts have long established that emails sent and received by public officials using government computers and email services are public documents and must be turned over on request from the public. State open government law requires public officials to balance the right to privacy with their obligations to hand over public documents. And Koopman maintains that three of the emails leaked to NorthWest Liberty News were personal in nature and should be exempted from public disclosure. These are simple determinations to make and the commission does not need a district court judge to make those determinations.
Lets call this what it is. The net effect of dragging these requests into court is to discourage requests for public documents. Any member of the public has a right to see public documents. But not everyone has the resources to hire a lawyer to get those documents nor should they have to.
The Montana Constitution and the statutes that emanate from it are clear. Government is to be transparent in all its actions. All meetings are to be open to the public and what are clearly public documents must be produced when requested.
Lets put the public back into the Public Service Commission: rescind the court action and hand over the emails in question.
To see what else is happening in Gallatin County subscribe to the online paper.
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What part of 'public' does PSC not get? - The Bozeman Daily Chronicle
Is the Big Bang in crisis? | Astronomy.com – Astronomy Magazine
Similar to the situation cosmologists confront today, however, the physicists of 1904 had not yet been able to address a few challenges. The medium through which they believed light traveled the luminiferous ether should have induced variations in the speed of light, and yet light always moves through space at the same rate. Astronomers observed the orbit of Mercury to be slightly different from what Newtonian physics predicted, leading some to suggest that an unknown planet, dubbed Vulcan, might be perturbing Mercurys trajectory.
Physicists in 1904 had no idea what powered the Sun no known chemical or mechanical process could possibly generate so much energy over such a long time. Lastly, scientists knew various chemical elements emitted and absorbed light with specific patterns, none of which physicists had the slightest idea how to explain. In other words, the inner workings of the atom remained a total and utter mystery.
Although few saw it coming, in hindsight, its clear that these problems were heralds of a revolution in physics. And in 1905, the revolution arrived, ushered in by a young Albert Einstein and his new theory of relativity. We now know that the luminiferous ether does not exist and that there is no planet Vulcan. Instead, these fictions were symptoms of the underlying failure of Newtonian physics. Relativity beautifully solved and explained each of these mysteries without any need for new substances or planets.
Furthermore, when scientists combined relativity with the new theory of quantum physics, it became possible to explain the Suns longevity, as well as the inner workings of atoms. These new theories even opened doors to new and previously unimagined lines of inquiry, including that of cosmology itself.
Scientific revolutions can profoundly transform how we see and understand our world. But radical change is never easy to see coming. There is probably no way to tell whether the mysteries faced by cosmologists today are the signs of an imminent scientific revolution or merely the last few loose ends of an incredibly successful scientific endeavor.
There is no question that we have made incredible progress in understanding our universe, its history, and its origin. But it is also undeniable that we are profoundly puzzled, especially when it comes to the earliest moments of cosmic history. I have no doubt that these moments hold incredible secrets, and perhaps the keys to a new scientific revolution. But our universe holds its secrets closely. It is up to us to coax those secrets from its grip, transforming them from mystery into discovery.
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Is the Big Bang in crisis? | Astronomy.com - Astronomy Magazine
Raytheon Technologies Board of Directors to Take Voluntary Compensation Reduction – PRNewswire
WALTHAM, Mass., May 14, 2020 /PRNewswire/ --Raytheon Technologies' (NYSE: RTX) Board of Directors has reduced non-employee director compensation by an amount equal to 20 percent of the director cash retainer. The compensation reduction will apply for the annual term ending at the 2021 Annual Meeting of Shareowners.
The Board's action follows a decision by CEO Greg Hayes to institute a temporary 10 percent base pay reduction for all salaried employees across its Pratt & Whitney and Collins Aerospace Systems businesses as well as the company's corporate offices. The temporary pay reductions announced last month by the company go into effect June 1st and extend through year-end.Company CEO Greg Hayes and Executive Chairman Tom Kennedy had previously volunteered to reduce their salaries by 20 percent for the same period.
Raytheon Technologies continues to monitor the crisis and is responding as needed to ensure the wellbeing of its employees, customers and suppliers, while protecting the long-term financial strength of the business.
About Raytheon Technologies
Raytheon Technologies Corporation is an aerospace and defense company that provides advanced systems and services for commercial, military and government customers worldwide. With 195,000 employees and four industry-leading businesses Collins Aerospace Systems, Pratt & Whitney, Raytheon Intelligence & Space and Raytheon Missiles & Defense the company delivers solutions thatpush the boundaries in avionics, cybersecurity, directed energy, electric propulsion, hypersonics, and quantum physics. The company, formed in 2020 through the combination of Raytheon Company and the United Technologies Corporation aerospace businesses, is headquartered in Waltham, Massachusetts.
Media ContactMichele QuintaglieC: 860.493.4364[emailprotected]
Investor ContactKelsey DeBriynC: 781.522.5141[emailprotected]
SOURCE Raytheon Technologies
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Raytheon Technologies Board of Directors to Take Voluntary Compensation Reduction - PRNewswire
OK, WTF Are Virtual Particles and Do They Actually Exist? – VICE
Last June, Boston University professor Gregg Jaeger travelled to Vxj, Sweden for a conference. It was the twentieth time that philosophers had gathered there to discuss questions that strike at the foundations of physics. Jaeger had been invited to give the opening talk, to speak about mysterious and sometimes controversial entities called virtual particles."
Whereas matter had long since been recognized to be made up of particles, the existence of virtual particles had been debated by philosophers of physics for at least thirty years. Mostly, they leaned towards their dismissal, but Jaeger is a believer.
Like ordinary particles, virtual particles come up incessantly in physicists work, in their theories, papers, and talks. But as their name suggests, they are far stranger than ordinary particles, which are already notoriously odd. Particles are the chief representatives of the world of the small, the quantum world. If you scaled everything up so that a particle was the size of a sand grain, you would be as tall as the distance from Earth to the Sun.
Physicists know from experience that particles are undoubtedly there, beyond sight. Virtual particles are much more elusive, to the point that the non-believers say they only exist in abstract math formulas. What does it even mean for virtual particles to be real?
Jaeger is a physicist-turned-philosopher, who published important quantitative results early in his career before spending the last ten years focused on the philosophy and interpretation of physics. He arrived at virtual particles as only the latest stop in a long journey of making sense of the quantum world.
There are two distinct narratives for virtual particles, and Jaeger subscribes to what philosophers call the realist position. Believers or realists argue that virtual particles are real entities that definitively exist.
In the realist narrative, virtual particles pop up when observable particles get close together. They are emitted from one particle and absorbed by another, but they disappear before they can be measured. They transfer force between ordinary particles, giving them motion and life. For every different type of elementary particle (quark, photon, electron, etc.), there are also virtual quarks, virtual photons, and so on.
Jaeger in his office. Image: Author
A useful analogy to the realist narrative of virtual particles is to imagine going to a big family reunion, full of cousins, parents, grandparents, and others. Each group of relatives represents some different type of particle, so for example, you and your siblings might all represent electrons, and your cousins might all represent photons. At this reunion, everyone happens to be a little stand-offish, mostly tucked away out of sight. When you see your sister, you walk up to shake hands, but when you look at her hand and go to grasp it, you find that your cousin has stuck his hairy hand in. He quickly shakes your hand and then your sisters. But when you look up, hes somehow disappeared, and your sister is walking away. Your cousin, the virtual photon, has just mediated the interaction between the two electrons of you and your sister.
Other philosophers have mainly upheld an opposing narrative, where virtual particles are not real and show up only in the mathematical theories and equations of quantum physics, which describe the particle world. The equations are correct, the doubters recognize, predicting all sorts of things like the peculiar magnetic properties of electrons and muons, for example.
But the entities called virtual particles are just parts of the math, these experts claim. Virtual particles have never been and cannot be directly observed, by their mathematical definition. They supposedly pop up only during fleeting particle interactions. And if they are real then they would possess seemingly unacceptable properties, like masses with values that can be squared (multiplied by themselves) to give negative numbers. They would be entirely out of the ordinary.
That physicists still claim these things to be real has haunted philosophers. Philosophers of physics, often highly trained physicists themselves, demand a story of reality that makes senseat least, as much as possible. Can the realist narrative really be true? Do bizarre things called virtual particles pop up and mediate all the interactions between observable particles?
As Jaeger explains, there are at least four different overarching mathematical theories of the quantum world. The most basic of these is called quantum mechanics. Virtual particles originate from a more advanced mathematical apparatus known as quantum field theory (QFT). If quantum mechanics is like the childrens book Clifford the Big Red Dog, then QFT is the Necronomicon, bound in skinfar more arcane and complex.
Physicists use quantum mechanics to explain the most fundamental quantum phenomena, like the simultaneous wave and particle nature of light. QFT on the other hand is used for predicting the results of extreme experiments at places like the Large Hadron Collider (LHC). QFT does the heavy lifting, in other words.
The LHC is famous for its scattering experiments, where two or more particles are collided together and scatter off one another. During the collision, old particles are destroyed and new ones created. Physicists perform collisions over and over again in highly controlled circumstances and try to predict what particles come out and how. Recalling the metaphor of a family reunion, scattering experiments tell the story of how likely it is that your sister walks out from the handshake, and not some other relativean odd and yet distinct possibility.
In QFT, the probability of what particle comes out is decided by a complicated equation. Physicists solve it with a clever trick. They write out the solution as a sum of much simpler terms (summands), which is then squared. Technically, the sum contains infinitely many terms, but for many scenarios only the first few terms matter. Each of the terms in the sum contains physical quantities related to the incoming and outgoing particles, like their momentum, mass, and charge, all of which can be directly observed. However, each term can also contain physical quantities (like mass or charge) that correspond to entirely different particles, which are never observed. These are what are known as the virtual particles.
Before the LHC existed, in the 1940s, the renowned physicist Richard Feynman introduced a diagrammatic technique that made the role of the virtual particles clear. For each term in the sum for the QFT calculation, a so-called Feynman diagram can be drawn that depicts the incoming and outgoing particles. Virtual particles are drawn popping up in the center. These diagrams greatly aid in doing the complicated calculations. For every line in a diagram, for example, a physicist simply sticks another variable in their solution.
Feynman diagrams can seem to provide a temptingly accurate picture of what goes on in an experiment. However, for any experiment, there are actually infinitely many different Feynman diagrams, one for each term in the sum. This poses an interpretive problem because it seems incoherent. The theory suggests that anytime particle relatives shake hands at the family reunion, every other relative (an infinite number of them!) also stick theirs hands in.
One of Feynmans well-known contemporaries, Freeman Dyson, addressed this problem by making it clear that Feynman diagrams did not show a literal picture of reality. They were only supposed to be used as an aid to doing the math. On the other hand, Feynman sometimes suggested that the pictures actually were representative of reality.
But regardless of their interpretation, the diagrammatic technique caught on. And the virtual particles in the diagrams and the mathematics became objects of constant reference for physicistseven though the math was only meant to predict the outcomes of scattering experiments. The process of particles colliding into each other, which one would naively expect to be about forces and energy, turned out to be about virtual particles.
Image: Wikipedia/Krishnavedala
The fundamental thing that makes you know that the physical world is there is forces. Like you bang into things, right? Jaeger said, hitting his hand on the desk in his office. Ow! So thats something there. There's a world out there that's transmitted by a force. But when you try to [mathematically] understand this process of transmission, from the point of view of whats out there, and whats its structure, you end up with these virtual particles.
Many physicists who focus on quantitative results believe in a reality filled with virtual particles because QFT performs astoundingly well, predicting the outcomes of countless experiments. And QFT is rampant with virtual particles.
I have no problem at all with the fact that these virtual particles are real things that determine the forces in nature (except for gravity), said Lee Roberts, an experimental physicist and professor at Boston University, located only two blocks down from Gregg Jaegers office.
Roberts helps lead current efforts to measure the magnetic properties of muon particles with greater precision than ever before at Fermilabs Muon g-2 experiment. And whatever the questions may be around the existence of virtual particles, physicists like Roberts can hardly interpret the properties of muons without them.
Muons are like heavy electrons, carrying negative electric charge and a quantum property called spin. Roughly speaking, the muons spin can be thought of like the actual spin of a tiny rotating top. The rotation of the muons intrinsic charge produces a small magnetic field, called its magnetic moment.
Because it acts like a tiny magnet, the muon interacts with other electromagnetic fields, which are represented in the particle world by photons. To calculate the interaction, physicists use a similar process as for scattering experiments, writing the solution as an infinite sum. The terms in the sum are represented by nothing other than Feynman diagrams, where one muon particle and one photon flies in, and one single muon flies out. Virtual particles are drawn in the center hairy relatives, sticking their hands in.
All these interactions sum up to give the muon an anomalous magnetic moment, anomalous compared to the results of theories that came before QFT. But with QFT, physicists have predicted the magnetic moment almost exactly, like marking off the lines on a football pitch blindfolded and getting them accurate to the width of a hair. The accuracy of these calculations relies indispensably on the virtual particles.
With QFT being so accurate, it is clear that there must be some kind of reality to it. Perhaps the question then is not so much whether virtual particles are real, but what exactly the general picture of reality is, according to QFT.
Oliver Passon is one of the physicist-philosophers who object to the notion that virtual particles are real. He earned his Ph.D. in particle physics and is a highly experienced physicist, but now focuses on education research at the University of Wuppertal in North Rhine-Westphalia, Germany. He studies how particle physics should be taught to high-school students, for whom it has become part of the standard curriculum.
Virtual particles are a mess, Passon summarized for Motherboard.
For Passon, the realist view arises from a sloppy interpretation of the math, and it has led physicists to make other interpretive mistakes, for example, in explaining the discovery of the Higgs boson at the LHC. He wrote about his views in a paper last year.
Passons objections can be explained in the context of the famous quantum mechanics test-case known as the double-slit or two-slit experiment. In a two-slit experiment, physicists fire particles such as photons one at a time at a wall with two tiny slits. The probability of where exactly a particle lands on the other side of the wall is related to the square of a sum, similarly as in a scattering calculation from QFT. But in this case there are only two terms in the sum, each reflecting the narrative of the particle passing through only one of the slits. Which slit does the particle pass through? Quantum mechanics cannot say, because the mathematics requires the term that represents each possibility to be summed with the other and squared.
The question whether one or the other thing happens makes no sense. Its not a tough questionits not even reasonable to ask, Passon said. This is what I take to be the key message of all of quantum mechanics.
The two-slit experiment seems to show that individual mathematical terms by themselves have no realism, and only their superposition (summation and squaring) have meaning. Thus, in Passons view, virtual particles that show up in individual QFT terms should not be considered real. This argument against virtual particles is known to philosophers as the superposition argument, and it can seem like a strong one.
But Jaeger thinks the argument is besides the point. Ironically, he sees this critique as being stuck in mathematical abstractions itself. He agrees that the individual terms cannot tell the whole story, "but it doesnt mean the particle didnt go through space, he said.
The mathematics may not tell which slit the particle passes through, but it doesnt mean that the mathematics is wrong. The mathematics still correctly predicts the passage of a particle through intervening space, and the probability of where it eventually lands. And in QFT, the mathematics indisputably relies on the presence of virtual particles.
Interestingly, quantum field theory actually says matter is fundamentally made up of fields rather than particles, let alone virtual particles. For every elementary particle, such as a photon, QFT says there is a fundamental field (such as a photon field) existing in space, overlapping with all of the other particle fields. Most of these fields are invisible to our eyes, with notable exceptions like the photon field.
Ask any physicist on the planet, whats our current best theory of physics, and theyre going to give you a theory of fields, said David Tong, a theoretical physicist and professor at the University of Cambridge. It doesnt include one particle in those equations [for fields]. Still, physicists more commonly refer to particles than their underlying fields, as particles can provide a more convenient and intuitive concept.
To question the existence of ordinary (non-virtual) particles would be counterproductive, according to Brigitte Falkenburg, a professor at the Technical University of Munich who wrote a comprehensive book on the subject, Particle Metaphysics.
The evidence against their existence is that they cannot be directly observed, but then, this was the argument of Galileos enemies, who refused to look through the telescope to observe Jupiters moons, Falkenburg said.
Particles and fields might instead be looked at as two different interpretations of the same thing. The physicist Matt Strassler has blogged extensively to try and clarify the interpretation of virtual particles based on an understanding of fields.
As he writes on his blog, particles can be thought of like permanent ripples in the underlying particle fields, like ripples fixed on the surface of water. Virtual particles on the other hand are more like fleeting waves.
As Jaeger points out, under this interpretation, the narrative of infinitely many virtual particles popping up makes more sense. There are only a finite number of particle fields, since only a finite number of elementary particles have been discovered. An infinitude of virtual particles popping up would be just like the infinitude of small changes that we can feel in a single gusting wind.
Jaeger is currently refining his own picture of virtual particles as fluctuations in the underlying quantum fields. The key part about these fluctuations for Jaeger is that they must conserve overall quantities like energy, charge and momentum, the key principles of modern physics.
In the end, there seems to be good reason not to think of virtual particles as ordinary, observable particles, but that whatever they are, they are real. The difficulty of interpreting their existence points at the complexity of the quantum field theory from which they originate.
As of now, no one knows how to replace QFT with a theory that is more straightforward to explain and interpret. But if they did, then they would have to settle the question of the true nature of the virtual particle, perhaps the most enigmatic inhabitant of the smallest of scales.
This article originally appeared on VICE US.
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OK, WTF Are Virtual Particles and Do They Actually Exist? - VICE
Physicist Brian Greene on learning to focus on the here and now – KCRW
The coronavirus pandemic is a reminder that things can change fast and unexpectedly. As much as we look for stability, things come and go, and we live and die. Theoretical physicist and mathematician Brian Greene explains why understanding the science behind the impermanence in our world can lead to a more fulfilling life.
He explains his theories with KCRWs Jonathan Bastian. This interview has been abbreviated and edited for clarity.
In your most recent book, you write about the concept of impermanence. When did that idea become apparent to you?
Brian Greene: I think at various levels of conscious awareness, we know that we are impermanent. And it hits us in different ways at different times, depending upon where we are mentally, spiritually and what's happening in the world around us.
When I was in college and seriously thinking about what I wanted to do, I had a conversation with a mentor of mine who told me he does mathematics because once you prove a theorem in mathematics, it's true forever, it will never not be true.
That just hit me. It was a powerful moment when I recognized that you can't say that about many things in the world. And that's when I started to really think about whats available in this life that does transcend our own impermanence.
How do you then arrive at the concept of impermanence?
There is this sensibility that if you can uncover the deep laws of the universe, you are touching something that was always true. One of the things I do in the book is explore the degree to which that is actually true. Does a law of physics, does quantum mechanics have any meaning or value or purpose in the absence of human beings, or in the absence of another life form that can contemplate it? What does a deep equation mean if there isn't any conscious awareness to contemplate it?
In the far future, as I argue in the book, it's quite likely there won't be any life forms. And without lifeforms to contemplate Einsteins equations, his theory of relativity, it's hard for me to see that they have any standing in terms of the permanence that we as living creatures aspire to.
How did you come to grips with this? Did you have some kind of existential awakening?
I definitely went through a dark stance from immersing myself in the idea that you are transcending human impermanence, whether it's quantum mechanics or relativity or what have you. That was how I lived my life for many decades. And then to recognize that that perspective is probably not right, that was a shift.
But then I had this other moment in, of all places, a Starbucks. A shift that happened inside of me, where I felt like a change in perspective from grasping for an ephemeral future to just focusing on the here and now.
...Do what we've heard from mindfulness teachers and sages and philosophers across the ages to focus on the here and now, as that is the only place in which value and meaning can actually have an anchor.
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Physicist Brian Greene on learning to focus on the here and now - KCRW