Showing posts sorted by date for query QUANTUM REALITY. Sort by relevance Show all posts

Tuesday, September 29, 2026

Cosmic lockdown: how the environment can isolate quantum fields

A simplified cosmological model suggests that decoherence can suppress quantum tunnelling, effectively locking fields into the vacuum state they have reached.

Sissa Medialab

video:
Adiabatic limit (μ̃→∞)： ground-state Wigner [mCOya84QF-g]
view more
Credit: Kaplanek et Al. JCAP 2026

The vacuum is not always so empty. "When we talk about a vacuum in cosmology, we do not mean completely devoid of energy," explains David Wands, Professor at the Institute of Cosmology & Gravitation at the University of Portsmouth. "A vacuum is rather a state in which a field sits at a minimum of its energy. The true vacuum is the lowest possible minimum, but there can also be local minima, which we call false vacua." We can picture this as a landscape made up of valleys of different depths: the true vacuum is the deepest one, while the others are false vacua. Something sitting in one of these depressions can remain "trapped" there even if, somewhere else, a lower-energy state exists. This is exactly what can happen to quantum fields, fundamental physical objects that permeate the Universe. A classical field is something that has a value at every position in space, like a magnetic field, whose strength changes from point to point. Quantum fields behave in a similar way, and their excitations appear as particles. In a new study published in JCAP, Robson Christie, Jaewoo Joo, Greg Kaplanek, Vincent Vennin and David Wands used a simplified model to investigate what determines which vacuum a field may end up in within an expanding Universe.

The case of the Higgs field

To understand why this question matters, the authors themselves point to the case of the Higgs field. Its vacuum value contributes to giving mass to the particles of the Standard Model — the theory that describes the known elementary particles and three of the four fundamental forces — and helps determine the structure of low-energy physics.

According to some calculations based on the Standard Model, it is possible that the Higgs field does not sit in the lowest possible energy state, but in a false vacuum, while at very large field values a second, deeper minimum may exist.

The study is not directly about the Higgs field, but uses it as a concrete example of what can happen when a field becomes trapped in a local minimum even though a lower-energy state is available.

“In principle, a transition to that deeper minimum would take the Universe into a radically different state, in which the structure of matter and the forces that govern it would be altered,” explains Robson Christie, a researcher at the School of Mathematics and Physics at the University of Portsmouth and first author of the study.

Such a transition can be made possible by a quantum phenomenon. Let us return to the picture of vacua as valleys separated by mountains. In classical physics, a system sitting at the bottom of the shallower valley can reach the deeper one only if it has enough energy to climb over the mountain between them. In quantum mechanics, by contrast, the state of the system can extend beyond the barrier, leaving a small probability that it will appear on the other side: this is quantum tunnelling.

No field is ever truly isolated

In their work, Christie and colleagues built a simplified model to understand how the environment affects the evolution of a field.
Many calculations of tunnelling treat the field as completely isolated. “We know, however, that perfect isolation is an idealisation,” explains Greg Kaplanek, a researcher at Syracuse University, New York. In reality, fields continuously interact with other fields and with what surrounds them — in other words, with their environment. “Think, for example, of quantum computers: we go to enormous lengths to protect the quantum information stored in these machines from the environment, because even weak interactions with it can quickly alter the quantum state. Something similar happens in cosmology: a field is never really alone.”

Interactions with the environment produce a phenomenon known as decoherence. A quantum system can exist in a superposition of different possibilities: using the analogy of a coin, it is not simply heads or tails, but a quantum state that includes both possibilities at once. Interaction with the environment makes it increasingly difficult to keep this superposition, causing the system to behave more and more like an ordinary classical system.

In the authors’ model, the environment is represented by other fields interacting with the main field. The latter can also initially be in a quantum superposition involving both vacua. One of the surprises of the study, however, is that the environment does not appear to play a decisive role in the initial choice of vacuum.

Light fields and heavy fields

What matters more is whether the field is “light” or “heavy” relative to the Hubble scale, that is, relative to the rate at which the Universe is expanding.
“A field that is heavy compared with the Hubble scale can quickly adjust to the changes as the Universe expands,” Christie explains, “and in this case it is highly likely to move towards the true vacuum, the deepest energy minimum.”

Something different happens for lighter fields. “If the expansion is too rapid compared with the dynamics of the field, the system cannot keep up with the changes,” Christie continues. “In this case there can remain a significant probability that the field will also end up in the false vacuum.”

In other words, the initial choice between the true and false vacuum is influenced mainly by the relationship between the field’s own dynamics and the rate of cosmic expansion.

Cosmic lockdown

So let us imagine a light field that has ended up in a false vacuum. What happens next?

In a perfectly isolated quantum system, tunnelling towards the other minimum would still be possible. But in the authors’ model, interaction with the environment produces decoherence and destroys the quantum properties needed to maintain a coherent superposition between the two vacua.

“The interesting thing is that it is not primarily the environment that decides where the field will end up,” explains Kaplanek. “Once the field has localised in one of the two minima, however, decoherence tends to keep it there. Tunnelling towards the other vacuum is strongly suppressed.”

This is the phenomenon the authors call “cosmic lockdown”: a kind of lock that stabilises the field in the vacuum it has reached. The authors interpret it as a manifestation of the quantum Zeno effect: under certain conditions, a quantum system that is continuously monitored can have much more difficulty moving from one state to another.

Of course, no one is literally observing the field in the model. “You do not need a conscious observer,” Kaplanek explains. “The environment continuously gathers information about the state of the system. This process destroys the coherence between the two possible vacua and makes tunnelling from one to the other much more difficult.”

Good news for our Universe?

The work remains a simplified model and does not show that our current Higgs vacuum is protected by cosmic lockdown. The result does, however, suggest an interesting principle: interactions with the environment can make a false vacuum more stable by suppressing tunnelling towards another state.
“If a mechanism of this kind were relevant in more realistic cosmological situations, then it could help stabilise a field that is already sitting in a false vacuum,” Wands concludes. “But understanding how far this can be applied to the Higgs field will require more realistic models.”

If our Higgs field really is sitting in a false vacuum, then cosmic lockdown points to at least one reassuring possibility: interaction with its surroundings could help make a transition to a radically different state even more difficult.

Unitary Schrödinger evolution [VIDEO]

SSE with L ∝ φ [VIDEO]

Journal

Journal of Cosmology and Astroparticle Physics

Method of Research

Data/statistical analysis

Article Title

Cosmic Lockdown: When Decoherence Saves the Universe from Tunneling

Article Publication Date

25-Sep-2026

Saturday, September 19, 2026

What we know (and still don't) about Canada's 'associate membership'

By Jorge Liboreiro

Published on 19/09/2026 - EURONEWS

The idea of making Canada the European Union's first "associate member" has caused a furore. Here's what we know and still don't know.

It's the head-turning, eye-popping announcement of the week: Ursula von der Leyen has invited Canada to make history by becoming the first-ever "associate member" of the European Union

"We want to bring the relationship with Canada to the highest level possible," the European Commission president said in her State of the Union speech.

The following day, speaking from the same lectern in Strasbourg, Canadian Prime Minister Mark Carney said his country "welcomes" the offer and hailed the dawn of an "alliance for the future".

"Europe and Canada are stronger together," he said.

The back-to-back speeches made international headlines, caused a political furore, inspired countless memes and even caught Donald Trump's attention. But they also left many burning questions unanswered.

Here's what we know – and still don't know – about the splashy idea.

There's just no precedent

The concept of "associate membership" is not envisioned in the EU treaties as such. And since it does not exist on paper, there is no precise playbook that Brussels can follow to make it reality.

A similar dilemma emerged earlier this year when German Chancellor Friedrich Merz proposed making Ukraine an "associate member" of the bloc. This, he said, should grant observer status in the decision-making bodies, gradual access to some EU programmes and mutual assistance in the event of a future attack.

Merz's surprise pitch received mixed reviews from capitals and was rebuffed by Kyiv, which worried the half-in, half-out rank would plunge it into accession limbo.

Commission officials say von der Leyen's vision fundamentally differs from Merz's because it is designed for countries outside Europe's geographic sphere that wish to be politically and economically closer to the bloc.

Brussels is confident the ground-breaking concept can be designed from scratch without the need to revise the EU treaties, a perilous avenue.

Some have suggested that a possible way forward lies with Article 217 of the EU treaties, which holds that "The Union may conclude with one or more third countries or international organisations agreements establishing an association involving reciprocal rights and obligations, common action and special procedure."

Carney, meanwhile, said the set-up should be "open enough that others can join".

It's not enlargement

One thing Carney made sure to stress is that his country would not pursue the conventional full-time membership that Ukraine, Moldova and other candidates are seeking.

According to the treaties, this process is available to "any European State", which means a nation on the other side of the Atlantic would not qualify.

"Canada is not in a position nor seeking to become a full member of the European Union. Therefore, it's a different framework," Carney said after his speech. "It's a framework that is relevant for a country that shares deep bonds with Europe."

Accession is a notoriously cumbersome process that requires candidates to adopt thousands of EU laws and align themselves with the bloc's world-class standards. Each step is subject to unanimity, creating multiple opportunities for vetoes.

Ottawa and Brussels want an arrangement that can be concluded much faster.

But it seems curiosity has been piqued: ahead of Carney's trip to Strasbourg, a poll showed that a whopping 49% of Canadians supported full-fledged EU membership.

The name is TBD

Though the headlines that emerged from Strasbourg all honed in on the striking "associate member" title, Carney did not outright endorse it. Instead, he stuck to his "alliance for the future" moniker, which is less politically charged.

"President von der Leyen used both terms: alliance for the future and associate membership. The nomenclature, the precise nomenclature, is a question for Europe," he said. "What matters is the substance."

For the Canadian premier, "associate membership" carries the connotation of ceding sovereignty to Brussels, something he vowed would not be the case under any circumstance.

"We are looking for partnerships that are complementary, that reinforce our sovereignty, and that's what is on offer here," he said. "Canadians are united that nobody is going to tell us what language we speak. No one is going to dictate our culture or with whom we can strike international agreements."

EU officials have brushed off the semantic clash. For them, the "alliance for the future" is the immediate deliverable and "associate membership" the long-term prospect.

It'll be put to a vote

After von der Leyen extended her invitation, the conservative opposition in Canada criticised Carney for seeking deeper ties with the EU without an electoral mandate.

In response, Carney cautioned the negotiations were still in early stages and committed to bringing the outcome to a final vote in the Canadian parliament.

"We will have a series of debates, I'm sure, in parliament (and) relevant committees. And ultimately, there will be a vote in the Canadian parliament for the final structure of the alliance that we're working on," he said. "It will all roll out transparently."

On the European side, it remains to be seen how von der Leyen's team will advance the novel concept through the legislative cycle. The executive has not yet said which department will supervise the work, though the Secretariat-General and DG Trade appear the likeliest candidates to take the reins.

"We're talking about a very ambitious project here, so this is going to require many services across the Commission. It's going to be a whole-of-government approach if you want to call it that," Olof Gill, the Commission's deputy chief spokesperson, said.

Gill insisted the talks would be carried out in close coordination with the member states, some of which were given a heads-up right before von der Leyen's speech.

"Big changes in the European Union only happen with the say-so of our member states, and that will always be the case," he said.

Ireland, Spain and France are among those who have expressed support for exploring the original idea. A high-level discussion on the matter is not excluded when EU leaders gather in October for a busy two-day summit in Brussels.

Later that month, von der Leyen and Carney will meet in Montreal, Quebec. This will be a chance for both to flesh out what exactly they have in mind.

Economy comes first

Still, Strasbourg already gave us a pretty good idea of the areas that von der Leyen and Carney have set their sights on.

Chief among them is commerce, building on the EU-Canada free trade deal, CETA, which still has to be ratified by 10 member states.

Von der Leyen said the goal should be to establish a "common prosperity and economic security space" encompassing intelligent manufacturing, energy, batteries, artificial intelligence, quantum, cyber, defence industry and the Arctic.

Carney echoed these areas and added broadband connections, semiconductors, liquefied natural gas and hydrogen to the list.

He also made sure to underscore Canada's position as a supplier of critical minerals, which Europe desperately wants to diversify to cut off Beijing's chokepoints.

"Canada has deposits of over 34 critical minerals, and we are among the top producers of the 10 most essential for the world's energy transition," he said.

"Our alliance can help fill Europe's need for reliable supply, Canada's need for advanced processing capabilities and our common objective to build complete value chains."

Another way to deepen ties is for Canada to participate in EU programmes. Canada is already part of the Horizon research platform and the SAFE defence initiative and wants to join the popular Erasmus+ for students and the €90 billion loan for Ukraine.

The four freedoms

Von der Leyen's invitation has raised the question of whether Canada, a country more than 6,000 kilometres away from continental Europe, will one day benefit from the bloc's four freedoms of movement: goods, services, capital and people.

The four freedoms are what make the single market seamless, borderless and effectively invisible. Norway, Iceland, Liechtenstein and Switzerland are the only nations outside the EU that enjoy this unfettered access. In return, they have been asked to apply thousands of EU laws without having a direct say in their approval.

Will Canada go as far?

In his speech, Carney said the burgeoning alliance should aim to enable free movement for young people between the EU and Canada.

"We should deepen our people-to-people ties, allowing our youth to live, work and study where they want on either side of the Atlantic," he said.

Carney also spoke of an "integrated market for financial services to broaden choice and reduce costs for our citizens, improve access to capital for our companies while maintaining our world-leading financial resilience".

Von der Leyen, however, did not mention any of the four freedoms.

The Commission has consistently said the four freedoms cannot be "cherry-picked". Earlier this year, Brussels reportedly rejected a post-Brexit overture from London to secure free movement of goods but not people.

Asked if any of them would be available under the "associate membership", Gill, the spokesperson, neither confirmed nor denied.

"Let's see where these discussions go," he said. "Right now, we have a shared commitment between the European Union and Canada that we want to strengthen our relations for mutual benefit, in our own interests."

Friday, September 18, 2026

What kills Schrödinger’s cat?

Underground experiment rules out a pioneering theory linking gravity to quantum decoherence

Foundational Questions Institute, FQXi

Decohering Schrödinger's Cat — image:
What mechanism causes the fuzzy quantum superposition state of an alive-and-dead cat to snap into a certain outcome, when Schrödinger opens his box?
view more
Credit: © FQxI/Gabriel Fitzpatrick (2026)

Somewhere between the microscopic realm of elementary particles and the macroscopic world of human beings, something strange happens: The rules of quantum physics, which work so exquisitely for tiny atoms, seem to lose their grip as objects grow larger. Pondering where and how this shift from small-scale quantum fuzziness to everyday sharp certainty happens gives rise to thought-experiment oddities like Schrödinger’s famous dead-and-alive cat. The process by which quantum phenomena like superposition—the paradoxical affliction of Schrödinger’s cat—fade into the classical reality we experience is known as decoherence. Now, a new FQxI-funded experiment has narrowed the field of possible explanations for decoherence, in particular ruling out a prominent theory linking gravity to the process. The results appeared in a paper in the New Journal of Physics in June 2026.

“One of the deepest questions in modern physics is why the strange quantum behavior that governs atoms and elementary particles seems to disappear in the macroscopic world we experience every day,” says FQxI member Catalina Curceanu, director of research and spokesperson for the VIP Collaboration at the National Laboratory of Frascati of the National Institute for Nuclear Physics (INFN-LNF) in Italy.

“One of the deepest questions in modern physics is why the strange quantum behavior that governs atoms and elementary particles seems to disappear in the macroscopic world we experience every day,” says Catalina Curceanu.

Conducted at the INFN Gran Sasso National Laboratory (INFN-LNGS), the world’s largest underground laboratory for fundamental physics research, the experiment tested one model in which decoherence is caused by gravity. Einstein’s general theory of relativity states that gravity manifests due to the warping of spacetime’s fabric around massive objects. In the 1960s, the Hungarian theoretical physicist Frigyes Károlyházy posited that spacetime is constantly rippling with tiny fluctuations that gradually erode quantum superpositions, preventing macroscopic objects from existing in the kind of quantum combinations imagined in Schrödinger’s famous cat paradox. His model continues to intrigue physicists and was recently revived, refined and reformulated by FQxI's Angelo Bassi and colleagues.

Telltale Trails

The fluctuations predicted by Károlyházy can’t be observed directly but, if they exist, they should cause charged particles to jiggle and accelerate randomly, giving telltale trails of electromagnetic radiation. This radiation would be so faint that it could easily be lost in electromagnetic background noise from sources like cosmic rays. That makes the Gran Sasso National Laboratory, which is tucked beneath 1.4 kilometers of radiation-dampening rock, an ideal place to conduct the search. “The natural shielding provided by the rock creates one of the quietest environments on Earth for detecting extremely rare physical phenomena,” says Curceanu.

The researchers used a detector made up of a coffee-mug-sized piece of high-purity germanium crystal, surrounded by layers of copper and lead shielding. They collected data for a total of 62 days. Then, they subtracted the expected background radiation from their measurements and looked for a signature that matched that predicted by the model.

The result: No signal.

“This absence of a signal is itself a major scientific result,” says Catalina Curceanu.

This doesn’t entirely rule out the possibility that gravity plays a role in quantum decoherence. But it does provide important information about where to look for a possible gravitational link. “This absence of a signal is itself a major scientific result,” says Curceanu. “By ruling out one of the oldest and most natural gravity-induced decoherence models, this work narrows the search for the theory describing the interplay between gravity and quantum mechanics, bringing us one step closer to understanding one of the deepest mysteries in fundamental physics.”

Exiting the Realm of Speculation

Károlyházy’s model rests on the notion that there is a fundamental limit to the precision with which we can locate objects and measure length. In the years since he proposed the model, this feature has emerged as a common thread in many contemporary theories seeking to unite quantum physics and gravity, including string theory and loop quantum gravity. “Every quantum gravity approach ends up with predicting the existence of a minimal length connected to the uncertainty in the measurement of spacetime,” says Kristian Piscicchia, a quantum physicist at the Enrico Fermi Research Center/INFN/VIP, in Italy, and the experimental lead on the new study.

Although many assume that quantum gravity cannot be probed by current technologies, the new research joins a growing body of work demonstrating that some ideas that involve both gravity and quantum theory are testable today. “Precision experiments are now reaching a level of sensitivity where they can test ideas that, until recently, belonged almost exclusively to the realm of theoretical speculation,” says Curceanu. “As sensitivity improves, the boundary between theory and measurement continues to move, opening new possibilities for discovering the fundamental principles that govern our universe.”

“Precision experiments are now reaching a level of sensitivity where they can test ideas that, until recently, belonged almost exclusively to the realm of theoretical speculation,” says Catalina Curceanu.

The research was supported by the Foundational Questions Institute, FQxI, through the Consciousness in the Physical World program. “The type of research that FQxI is encouraging brings teams together across generations, across boundaries, across disciplines,” says Curceanu. “It really can act as incubators of new ideas.”

You can read more about the team’s grants in the FQxI article: “Can We Feel What It's Like to Be Quantum?” by Brendan Foster.

Journal reference: Nicola Bortolotti, Kristian Piscicchia, Alessio Porcelli, Matthias Laubenstein, Simone Manti, Antonino Marcianò, Federico Nola and Catalina Curceanu, "Experimental exclusion of a generalized Károlyházy gravity-induced decoherence model," New J. Phys. 28 064511 (2026). DOI 10.1088/1367-2630/ae774c

ABOUT FQxI

The Foundational Questions Institute, FQxI, catalyzes, supports, and disseminates research on questions at the foundations of science, particularly new frontiers in physics and innovative ideas integral to a deep understanding of reality but unlikely to be supported by conventional funding sources. Visit FQxI.org for more information.