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Conceptual diagram of the calculation of density fluctuation correlations in the early universe based on a low-dimensional matter field theory using holography. Credit: KyotoU/Yasuaki Hikida

A team of researchers at Kyoto University is exploring the use of higher dimensions in de Sitter space to explain gravity in the early universe. By developing a method to compute correlation functions among fluctuations, they aim to bridge the gap between Einsteins theory of general relativity and quantum mechanics. This could potentially validate superstring theory and enable practical calculations about the early universes subtle changes. Although initially tested in a three-dimensional universe, the analysis may be extended to a four-dimensional universe for real-world applications.

Having more tools helps; having the right tools is better. Utilizing multiple dimensions may simplify difficult problems not only in science fiction but also in physics and tie together conflicting theories.

For example, Einsteins theory of general relativity which resides in the fabric of space-time warped by planetary or other massive objects explains how gravity works in most cases. However, the theory breaks down under extreme conditions such as those existing in black holes and cosmic primordial soups.

An approach known as superstring theory could use another dimension to help bridge Einsteins theory with quantum mechanics, solving many of these problems. But the necessary evidence to support this proposal has been lacking.

Now, a team of researchers led by Kyoto University is exploring de Sitter space to invoke a higher dimension to explain gravity in the expanding early universe. They have developed a concrete method to compute correlation functions among fluctuations on expanding universe by making use of holography.

We came to realize that our method can be applied more generically than we expected while dealing with quantum gravity, says Yasuaki Hikida, from the Yukawa Institute for Theoretical Physics.

Dutch astronomer Willem de Sitters theoretical models describe space in a way that fits with Einsteins general theory of relativity, in that the positive cosmological constant accounts for the expansion of the universe.

Starting with existing methods for handling gravity in anti-de Sitter space, Hikidas team reshaped them to work in expanding de Sitter space to more precisely account for what is already known about the universe.

We are now extending our analysis to investigate cosmological entropy and quantum gravity effects, adds Hikida.

Although the teams calculations only considered a three-dimensional universe as a test case, the analysis may easily be extended to a four-dimensional universe, allowing for the extraction of information from our real world.

Our approach possibly contributes to validating superstring theory and allows for practical calculations about the subtle changes that rippled across the fabric of our early universe.

Reference: Three-Dimensional de Sitter Holography and Bulk Correlators at Late Time by Heng-Yu Chen and Yasuaki Hikida, 3 August 2022, Physical Review Letters.DOI: 10.1103/PhysRevLett.129.061601

Funding: JSPSGrant-in-Aid for Scientic Research, Grant-in-Aid for Scientic Research, Grant-in-Aid for Transformative Research Areas (A)Extreme Universe

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Superstring Theory and Higher Dimensions: Bridging Einstein's Relativity and Quantum Mechanics - SciTechDaily

The battle over the heft of a hard-to-detect particle is heating up. Whats at stake? Only the leading theory describing all known matter in the universe.

A recalculation of the mass of an elementary particle, the W boson, has increased the tension between measurements from competing particle collider experiments. The ultimate outcome could bolster the standard model of particle physics, which describes the fundamental forces and quantum bits that make up everything we see in the cosmos. Or it could reveal signs of the standard models breakdown, depending on which labs answer prevails.

A reanalysis of old data from the Large Hadron Colliders ATLAS experiment yields a W boson mass of about 80,360 million electron volts, or MeV. Researchers with the experiment, at CERN in Geneva, reported the measurement March 23 at the Rencontres de Moriond conference in La Thuile, Italy. The revised value is closely aligned with predictions from the standard model.

It also boasts reduced uncertainty from the researchers previous analysis of the data, which they reported in 2018, increasing their confidence that they got the mass right.

But the updated mass is at odds with that of another group. In 2022, scientists from the Collider Detector at Fermilab, or CDF, experiment shocked the physics community with a measurement of 80,434 MeV about 100 MeV heavier than expected (SN: 4/7/22). If the CDF report is correct, it implies that something is off with the standard model that has persevered in the face of every experimental challenge thrown at it over the last 50 years.

The W boson is responsible for the weak force, one of three fundamental forces in the standard model (SN: 2/5/83). And its the only mass of a particle in the standard model that can be calculated, says theoretical physicist Sven Heinemeyer of the Karlsruhe Institute of Technology in Germany. That is, the standard model theory yields a specific mass for the W boson, whereas the masses of other particles such as electrons and quarks are inputs and can be as far as the theory is concerned any value. Finding a W boson mass thats different from standard model predictions would show the current theory is wrong.

The ATLAS reanalysis offers a stronger counterpoint to the CDF claim than the earlier ATLAS analysis of the same data. The new analysis is an important confirmation of our previous result, says Andreas Hoecker, a physicist at CERN.

The latest ATLAS value widens the chasm that separates CDFs mass measurement from the herd of other studies. But it shouldnt be seen as erasing CDFs standard model challenge, says Duke University physicist Ashutosh Kotwal, a member of the CDF collaboration.

The perspective on the CDF [announcement of a heavy W boson in 2022] does not change because of the ATLAS reanalysis, Kotwal says. Because the reanalysis is based on data that ATLAS already released in 2017, he says, the fact that ATLAS obtains a similar value as before is to be expected.

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Heinemeyer, who is not affiliated with ATLAS or CDF, sees a shift in the W boson mass landscape, but no sign of a resolution of the discrepancy.

Having one new measurement is not enough, Heinemeyer says. If more and more measurements were to come out now from ATLAS and [other experiments], and they would all be in the same ballpark, at some point the community would decide CDF did something wrong.

The next word on the W boson mass will probably come with pending studies from ATLAS and other experiments at CERN. The CDF experiment shut down in 2011, so it will not contribute further to the debate.

In the meantime, researchers hope to scrutinize each others analyses to search for clues that might help explain discrepancies in W boson mass measurements. The CDF April 2022 paper provides a number of cross-checks of the CDF methodology and is transparent, Kotwal says. I look forward to detailed discussions of the ATLAS methodology.

In the end, the conflict might reveal a new crack in the standard model. Or it could turn out to be another example of one of the most successful theories in history standing strong.

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The W boson might not be heavier than expected after all - Science News Magazine

Aaron Perine

04/01/2023 02:11 pm EDT

Ant-Man and the Wasp: Quantumania star Paul Rudd talked to a NASA physicistabout Quantum Science. In the video from Space.com, Dr. Ethan Elliot explained what kinds of strides they've made to the Marvel actor. Rudd is always down to help educate the youth and some of these findings are truly wild. Down in the Cold Atom Lab at NASA, they're studying topics that will interest prospective STEM students and beyond. Just like in the movies, quantum physics can refer to particles that exist in two places at once. This kind of science feels like fiction but actually influences some technologies we use everyday like GPS or MRI scanners.

"Quantum science is behind many of the technologies that we use every day, including your phone, computer, GPS, or even MRI scanners for medical imaging," Elliot told the superhero. "In the movies, you can shrink down and go into the quantum realm. We can't do that, but what we can do is make the quantum realm itself bigger."

In a press event from before Quantumania released, Rudd described what he loves about this character. "Well, I think what I like most about him is that he is a regular guy who has reservations about all of this, still. And that, you know, he's just a dad," Rudd shared. "I like the fact that he is kind of a part of this group with some pretty impressive people, and superheroes, and that he would be the first guy to say, "What the hell am I doing here? This makes no sense at all."

"And, you know, he's a real person. And so you want to play, I mean, as an actor, somebody who is relatable and hopefully a sympathetic person. And somebody that, you know, you understand maybe what they're going through. And I like that," he added. "I like playing the father aspect. I like playing the, trying to, you know, wrap my brain around the situation that I find myself in. So his human quality is the thing that I like the most. And as opposed to probably his cyborg quality, which is the, you know, the part I don't like. No, there's nothing about the character that I don't. I like the guy. Yeah. I mean, I'm biased, I guess, but yeah."

Here's how Marvel describes the trip into the Quantum Realm: "In the film, which officially kicks off phase 5 of the Marvel Cinematic Universe, Super-Hero partners Scott Lang (Paul Rudd) and Hope Van Dyne (Evangeline Lilly) return to continue their adventures as Ant-Man and the Wasp. Together, with Hope's parents Hank Pym (Michael Douglas) and Janet Van Dyne (Michelle Pfeiffer), the family finds themselves exploring the Quantum Realm, interacting with strange new creatures and embarking on an adventure that will push them beyond the limits of what they thought was possible. Jonathan Majors joins the adventure as Kang."

Do you find this science fascinating? Let us know down in the comments!

Disclosure: ComicBook is owned by CBS Interactive, a division of Paramount. Sign up for Paramount+ by clicking here.

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Ant-Man and the Wasp: Quantumania Star Paul Rudd Discusses Quantum Physics With NASA - ComicBook.com

What does quantum mechanics, the most successful theory ever proposed by physics, teach us about reality? The starting point for most philosophers of physics is that quantum mechanics must somehow provide a description of the world as it is independently of us, the users of the theory.

This has led to a large number of incompatible worldviews. Some believe the implication of quantum mechanics is that there are parallel worlds as in the Marvel Comic universe; some believe it implies signals that travel faster than light, contradicting all that Einstein taught us. Some say it implies that the future affects the past.

According to QBism, an approach developed by Christopher Fuchs and me, the great lesson of quantum mechanics is that the usual starting point of the philosophers is simply wrong. Quantum mechanics does not describe reality as it is by itself. Instead, it is a tool that helps guide agents immersed in the world when they contemplate taking actions on parts of it external to themselves.

The use of the word agent rather than the familiar observer highlights that quantum mechanics is about actions that participate in creating reality, rather than observations of a reality that exists independently of the agent.

QBism and its homophone, the art movement Cubism, share the understanding that reality is more than what a single agents perspective can capture. However, unlike the art movement, QBism does not attempt to represent reality. It does not attempt to bring the different perspectives together in one third-person view. QBism is fundamentally anti-representational and first person.

This puts QBism in direct contradiction with the two pillars of the 19th-century conception of a mechanistic universe. One is that nature is governed by physical laws in the same way that a mechanical toy is governed by its mechanism. The other is that it is, in principle, possible to have an objective view of the universe from the outside from a Gods eye or third-person standpoint.

This mechanistic vision is still dominant among 21st-century scientists. For instance, in their 2010 book The Grand Design, Stephen Hawking and Leonard Mlodinow write: It is hard to imagine how free will can operate if our behaviour is determined by physical law, so it seems that we are no more than biological machines and that free will is just an illusion.

Instead, the QBist vision is that of an unfinished universe, of a world that allows for genuine freedom, a world in which agents matter and participate in the making of reality.

A key aspect of quantum mechanics is randomness. Rather than making firm predictions, quantum mechanics is concerned with the probabilities for potential measurement outcomes. The physicist Ed Jaynes famously expressed that to understand quantum mechanics, one has to understand probability first.

In this spirit, QBisms starting point is the personalist Bayesian approach to probability (originally a method of statistical inference and now a fully fledged theory of decision making under uncertainty). In this approach, probabilities are an agents personal degrees of belief.

So rather than describing the statistics of some experiment, probabilities provide guidance to agents on how they should act. In other words, probabilities are not descriptive but normative analogous to an instruction manual. It turns out that the standard probability rules can be derived from the (normative) principle that ones probabilities should fit together in a way that guards against a sure loss when used for making decisions.

QBisms great insight was that the probabilities that appear in quantum mechanics are no different. They are not, as in the standard view, fixed by physical law, but express an agents personal degrees of belief about the consequences of measurement actions the agent is contemplating.

In QBism, the role of the quantum laws is to provide extra normative principles about how an agents probabilities should fit together. Rather than providing a description of the world, the rules of quantum mechanics are an addition to the standard probability rules; to classical (non-quantum) decision theory. They assist physicists in decisions such as how to design a quantum computer in order to minimise the probability of error, or what atoms to use in an atomic clock in order to increase the precision of time measurements.

Just like observer, the term measurement can be misleading because it suggests a pre-existing property that is revealed by the measurement. Instead, a measurement should be thought of as an action an agent takes to elicit a response from the world. A measurement is an act of creation that brings something entirely new into the world, an outcome that is shared between the agent and the agents external world.

Quantum mechanics is often depicted as weird and hard, or indeed impossible, to understand. As a matter of fact, the weirdness of quantum mechanics is an artefact of looking at it the wrong way. Once the two main QBist insights - that the quantum rules are guides to action and that measurements do not reveal pre-existing properties - are taken on board, all quantum paradoxes disappear.

Take Schrdingers cat, for example. In the usual formulation, the unfortunate animal is described by a quantum state taken to be a part of reality and implying that the cat is neither dead nor alive.

The QBist, by contrast, does not regard the quantum state as a part of reality. The quantum state a QBist agent might assign has no bearing on whether the cat is alive or dead. All it expresses is the agents expectations concerning the consequences of possible actions they might take on the cat. Unlike most interpretations of quantum mechanics, QBism respects the fundamental autonomy of the cat.

Or take quantum teleportation. According to a common way of presenting this operation, a particles quantum state, again regarded as a part of reality, disappears at one place (A) and mysteriously reappears at another (B) - quiteliterally as in a transporter in the Star Trek science fiction series.

For a QBist, however, nothing real is transported from A to B. All that happens in quantum teleportation is that an agents belief about the particle at A becomes, after the operation, the same agents belief about a particle at B. The quantum state that expresses the agents belief about the particle at A initially is mathematically identical to the quantum state that expresses that same agents belief about the particle at B after the operation. Quantum teleportation is a powerful tool used in applications such as quantum computing, but in QBism there is nothing counter-intuitive or weird about it.

QBism is an ongoing project. It spells out clearly the meaning of all mathematical objects in the theory and is thus a fully developed interpretation of quantum mechanics. Yet, QBism is also a programme for developing new physics and has already yielded deep insights even if it is still a work in progress.

QBism has also led to a fruitful dialogue with the kindred philosophical schools of thought of pragmatism and phenomenology. Its vision of the world is one in which agents possess genuine freedom and respect each others autonomy. I like to think that this is what quantum mechanics has been trying to tell us about reality all along.

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'QBism': quantum mechanics is not a description of objective reality it reveals a world of genuine free will - The Conversation

Imperial physicists have performed the double-slit experiment in time, using materials that can change optical properties in femtoseconds, providing insights into the nature of light and paving the way for advanced materials that can control light in both space and time.

Imperial physicists have recreated the famous double-slit experiment, which showed light behaving as particles and a wave, in time rather than space.

In a groundbreaking development, Imperial College London physicists have recreated the historic double-slit experiment, which demonstrated light behaving as both particles and a wave, in time rather than space. By using materials that can alter their optical properties in femtoseconds, the team successfully fired light through a thin film of indium-tin-oxide, creating temporal slits for light to pass through. The experiment not only offers insights into the fundamental nature of light but also serves as a stepping stone for developing advanced materials to control light in both space and time. These materials could potentially contribute to new technologies and help study fundamental physics phenomena, such as black holes.

The experiment relies on materials that can change their optical properties in fractions of a second, which could be used in new technologies or to explore fundamental questions in physics.

The original double-slit experiment, performed in 1801 by Thomas Young at the Royal Institution, showed that light acts as a wave. Further experiments, however, showed that light actually behaves as both a wave and as particles revealing its quantum nature.

These experiments had a profound impact on quantum physics, revealing the dual particle and wave nature of not just light, but other particles including electrons, neutrons, and whole atoms.

Now, a team led by Imperial College London physicists has performed the experiment using slits in time rather than space. They achieved this by firing light through a material that changes its properties in femtoseconds (quadrillionths of a second), only allowing light to pass through at specific times in quick succession.

Lead researcherProfessor Riccardo Sapienza, from the Department of Physics at Imperial, said: Our experiment reveals more about the fundamental nature of light while serving as a stepping-stone to creating the ultimate materials that can minutely control light in both space and time.

Details of the experiment are published today (April 3, 2023) in the journal Nature Physics.

Project member Romain Tirole adjusts the equipment used in the study at Imperial College London. Credit: Thomas Angus, Imperial College London

The original double-slit setup involved directing light at an opaque screen with two thin parallel slits in it. Behind the screen was a detector for the light that passed through.

To travel through the slits as a wave, light splits into two waves that go through each slit. When these waves cross over again on the other side, they interfere with each other. Where peaks of the wave meet, they enhance each other, but where a peak and a trough meet, they cancel each other out. This creates a striped pattern on the detector of regions of more light and less light.

Light can also be parcelled up into particles called photons, which can be recorded hitting the detector one at a time, gradually building up the striped interference pattern. Even when researchers fired just one photon at a time, the interference pattern still emerged, as if the photon split in two and travelled through both slits.

In the classic version of the experiment, light emerging from the physical slits changes its direction, so the interference pattern is written in the angular profile of the light. Instead, the time slits in the new experiment change the frequency of the light, which alters its colour. This created colours of light that interfere with each other, enhancing and cancelling out certain colours to produce an interference-type pattern.

The material the team used was a thin film of indium-tin-oxide, which forms most mobile phone screens. The material had its reflectance changed by lasers on ultrafast timescales, creating the slits for light. The material responded much quicker than the team expected to the laser control, varying its reflectivity in a few femtoseconds.

The material is a metamaterial one that is engineered to have properties not found in nature. Such fine control of light is one of the promises of metamaterials, and when coupled with spatial control, could create new technologies and even analogues for studying fundamental physics phenomena like black holes.

Co-authorProfessor Sir John Pendrysaid: The double time slits experiment opens the door to a whole new spectroscopy capable of resolving the temporal structure of a light pulse on the scale of one period of the radiation.

The team next want to explore the phenomenon in a time crystal, which is analogous to an atomic crystal, but where the optical properties vary in time.

Co-authorProfessor Stefan Maiersaid: The concept of time crystals has the potential to lead to ultrafast, parallelized optical switches.

Reference: Double-slit time diffraction at optical frequencies by Romain Tirole, Stefano Vezzoli, Emanuele Galiffi, Iain Robertson, Dries Maurice, Benjamin Tilmann, Stefan A. Maier, John B. Pendry and Riccardo Sapienza, 3 April 2023, Nature Physics.DOI: 10.1038/s41567-023-01993-w

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Time-Bending Experiment: Physicists Reveal Quantum Nature of ... - SciTechDaily