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Resolving the black hole firewall paradox—by calculating what a real astronaut would compute at the black hole's edge.

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Defining a ‘quantum clock’ and a 'quantum ruler' could help those attempting to unify physics—and solve the mystery of vanishing time.

Our Place in the Multiverse
Calculating the odds that intelligent observers arise in parallel universes—and working out what they might see.

Sounding the Drums to Listen for Gravity’s Effect on Quantum Phenomena
A bench-top experiment could test the notion that gravity breaks delicate quantum superpositions.

Watching the Observers
Accounting for quantum fuzziness could help us measure space and time—and the cosmos—more accurately.


FQXi BLOGS
December 15, 2017

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The Sudoku Universe, Why Real Numbers Are Not Really (Ontologically) Real, & (Not) Fine-Tuning Quantum Theory: New Podcast
By ZEEYA MERALI • Nov. 24, 2017 @ 22:19 GMT

Wikipedia
Do we live in a giant Sudoku puzzle? Are real numbers really real? Does free will emerge from quantum mechanics? Consciousness? Agency? Is the future open, or already set? Is reality fundamentally random or deterministic? What is fundamental anyway? And what is the fine-tuning problem of quantum mechanics -- and how do we deal with it?

These are some of the questions on a special edition of the podcast, featuring interviews that Brendan and I recorded at the Emergent Quantum Mechanics meeting in London, in October.

First up, quantum physicist Nicolas Gisin, of the University of Geneva, makes an unconventional case for the mainstream view that quantum theory is inherently indeterministic. He starts by arguing that real numbers are not really (ontologically) real, but random — and as a result, both classical mechanics, which is built on real numbers, and quantum mechanics are inherently indeterministic—giving us an open future.

Free Podcast

Real numbers are not (ontologically) real, says Nicolas Gisin; living in a Sudoku Universe, with Emily Adlam; FQXi launches a new essay contest and large grant round, with Anthony Aguirre and Jan Wallaczek; & fine-tuning quantum theory, with Matt Leifer.

LISTEN:

Go to full podcast

Taking the opposing stance is Emily Adlam, an expert on the philosophy of quantum theory, at the University of Cambridge. She advocates a deterministic atemporal “Sudoku Universe.” She notes that someone trying to follow the logic of a Sudoku grid, by reading numbers from the left to right, may be fooled into thinking they are looking at an undetermined probabilistic sequence of numbers. But step back and take a view of the grid as a whole, and you will see how all the seemingly random entries are uniquely determined, by atemporal rules. Maybe our universe is similarly determined, she suggests.

In addition to the fight over the (in)deterministic status of reality, the EmQM17 meeting was especially exciting for FQXi folk because we announced a couple of new initiatives there. On the podcast, Brendan tells us more about one of them: this year’s essay contest, which asks “What is Fundamental?

FQXi’s directors Max Tegmark and Anthony Aguirre also teased the launch of the new large grant round on Agency in the Physical World, in partnership with the Fetzer Franklin Fund (FFF), at the meeting. This attempts to link consciousness, intelligence and agency to quantum theory. So, for the podcast, we asked Anthony and FFF’s Jan Wallczek what they hope to bring out with this collaboration. Does it even make sense to link these topics together?

And finally, quantum theorist Matt Leifer of Chapman University outlines the fine-tuning problems that plague quantum theory. For instance, we know that while entanglement enables instantaneous influences between particles, this quantum property cannot be used to send useful information or signals at faster than light speeds. Yet, this feature doesn’t fall naturally out of the rules of quantum theory—or out of other theories physicists are investigating that may underlie quantum theory. Instead, this constraint has to be imposed by hand. Leifer explores possible ways around such fine-tuning issues.

So, what are your (short) answers to the questions posed in the podcast? (Long answers about what is fundamental can be submitted directly to the essay contest!)

Agents in the Physical World: Aguirre and Tegmark

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What Is “Fundamental”? – FQXi’s New Essay Contest
By BRENDAN FOSTER • Oct. 28, 2017 @ 13:45 GMT

We at the Foundational Questions Institute have often been asked what exactly “foundational” means, and what relation it holds to “fundamental” as a term describing some branches of physics. Today we’re happy to turn the tables.

It is time for the next FQXi essay contest, and so we ask, What Is “Fundamental”?

We have many different ways to talk about the things in the physical universe. Some of those ways we think of as more fundamental, and some as “emergent” or “effective”. But what does it mean to be more or less “fundamental”? Are fundamental things smaller, simpler, more elegant, more economical? Are less-fundamental things always made from more-fundamental? How do less-fundamental descriptions relate to more-fundamental ones?

We invite interesting and compelling explorations, from detailed worked examples through thoughtful rumination, of the different levels at which nature can be described, and the relations between them.

This year’s contest is part of our program Agency in the Physical World, operated with and sponsored by The Fetzer Franklin Fund. Help also comes from co-sponsors The Peter and Patricia Gruber Foundation.

We are open for entries from now until January 22, 2018. See our contest pages for the usual rules and timeline. Please share this info with all of your fellow thinkers and writers. Good luck!
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Agency in the Physical World – FQXi’s Next Research Program
By BRENDAN FOSTER • Oct. 28, 2017 @ 13:40 GMT

During our ten year history, we have worked to grow a community of researchers with an ever-widening realm of expertise. The important word here is community — our mission is to connect researchers who might have otherwise never known about each other.

Part of our strategy has been the use of themed programs — The Nature of Time, Physics of Information, The Physics of What Happens. Our most recent program attracted neurophysicists, computer scientists, sociologists, as well as the more “usual” physicists, mathematicians, and philosophers, together under the theme of Physics of the Observer.

We are proud now to announce our next venture, Agency in the Physical World. It follows our intellectual trajectory over the past programs, drawing deep connections from the most fundamental descriptions in physics and cosmology, to description in terms of observers, agents, and conscious beings. The program is a partnership between FQXi and the Fetzer Franklin Fund, a philanthropic organization dedicated to supporting foundational questions at the frontiers of physics, biology, and consciousness research.

The program features our familiar components for building community: a conference, essay contests, Large grants, and Mini-Grant rounds. Our first essay contest has just launched, and the Large Grant round will open in the coming weeks — please stay tuned for that announcement.

The program also supports research by the two “B-Area” centers — B for Boston and (San Francisco) Bay — formed during FQXi’s Physics of the Observer program. The work of the B-Area centers will try to better understand agency in physical systems through their capabilities to learn, to predict, to process information, and to choose. The centers also will serve as hubs for visits and other interactions that connect all researchers around the world funded by the APW program.

We envision the APW program will lead researchers to question how we define, identify, and measure agency, intelligence, and consciousness, and to investigate how these concepts fit into our current physical theories. These questions are contentious and difficult, even within the context of FQXi’s usual ambit of thorny topics.

But of course, that’s why we’re asking them!
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Schrödinger’s Cat Meowing Between Many Worlds and Collapse Models
By CATALINA CURCEANU • Jul. 28, 2017 @ 16:59 GMT

This post is co-written by FQXi members Catalina Curceanu (LNF-INFN, Italy) and Angelo Bassi (Univ. of Trieste and INFN, Italy):

In May, we organised an FQXi-sponsored workshop dedicated to Quantum Foundations at the Laboratori Nazionali di Frascati, LNF-INFN, in Italy, on "'Events' as we see them: experimental test of the collapse models as a solution of the measurement problem." (The event was co-organised with our colleague Kristian Piscicchia, of the Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi Roma, and LNF-INFN Frascati, Italy.)

The aim of the workshop was to discuss the possible limits of the validity of "standard quantum mechanics" and, related to this, collapse models and, more generally, theories which go beyond standard quantum theory and the experiments aiming to test them. In this context, the role which gravity might play was vividly discussed.

From the theoretical point of view, since the almost 100 years old Einstein-Bohr debate, quantum mechanics never stopped raising questions about its interpretation and possible limits. In particular, the transition from the microscopic world, where systems are observed in a superposition of different quantum states, to the macroscopic world, where systems have well defined properties (the so-called "measurement problem"), continues to puzzle (at least part of) the scientific community. For this reason theories/models beyond the standard quantum formulation are explored.

From the experimental point of view quantum theory is certainly the best verified available theory. It is therefore a very compelling challenge to look for possible small violations predicted by alternative theories/models. The aim of ambitious experiments is either to put stronger observational bounds on the new models, i.e. on the models parameters, or, much more exciting, to find violations of standard quantum mechanical predictions. In this framework, a deeper understanding of the possible limits of the validity of the quantum superposition principle is a real experimental challenge.

40 experts and young scientists, theoreticians and experimentalists, and also some philosophers, took part to the workshop and had vivid discussions.

In what follows, we present some of the items discussed during the workshop: Schrödinger’s cat meowing.

How well can we find out whether a wave function has collapsed? asks Roderich Tumulka of Eberhard-Karls University. If the GRW (Ghirardi-Rimini-Weber) theory were true, then how could we measure the number of collapses that have occurred for a given physical system in a given time interval? Roderich provided a mathematical analysis of some simple cases. It turns out that there are limitations to knowledge—that is, that some well-defined quantities cannot be reliably measured empirically.

Matteo Morganti of University of Roma Tre, Roma, discussed the attempt(s) to solve the measurement problem by making quantum mechanics a ‘many-world theory’. Starting from the naïve idea that measurement events literally cause the universe to branch, he moved back to the original ‘relative-state’ proposal made by Everett, and assessed to what extent it really qualifies as a many-world formulation of quantum mechanics. In the process, he considered, albeit briefly, some important issues concerning probabilities, empirical adequacy, decoherence and the philosophical status of the theory (or theories) in question.

Experimental bounds on collapse models from gravitational wave detectors were illustrated by Matteo Carlesso, Univ. of Trieste, Italy. Wave function collapse models postulate a fundamental breakdown of the quantum superposition principle at the macroscale. Upper bounds on the collapse parameters, which can be inferred by the gravitational wave detectors LIGO, LISA Pathfinder and AURIGA were shown in the framework of the Continuous Spontaneous Localization (CSL) model. These experiments exclude a large portion of the CSL parameter space at high correlation length, or rc, values.

Kristian Piscicchia has shown that for low values of rc, including that originally proposed by GRW, the best constraints come from the measurement of the spontaneous radiation. The interaction with the collapsing stochastic “noise” causes the emission of electromagnetic radiation for charged particles, which is not predicted by standard quantum mechanics, an effect known as spontaneous radiation emission. Comparing the X-ray emitted spectrum measured with ultra-pure Germanium detectors with the expected spontaneous radiation prediction allows to obtain the most stringent limit on the lambda collapse parameter for values of rc below the micron range, and in the near future orders of magnitude better limits are reachable.

An interesting presentation about Cosmic Inflation and Quantum Mechanics was held by Jerome Martin of CNRS, France. According to cosmic inflation, the inhomogeneities in our universe are of quantum mechanical origin. This scenario was recently spectacularly confirmed by the data obtained by the European Space Agency (ESA) Planck satellite. In fact, cosmic inflation represents the unique situation in physics where quantum mechanics and general relativity are needed to establish the predictions of the theory and where, at the same time, we have high accuracy data at our disposal to test the resulting framework. So inflation is not only a phenomenologically very appealing theory but it is also an ideal playground to discuss deep questions in a cosmological context. Jerome reviewed and discussed those quantum-mechanical aspects of inflation. He explained why inflationary quantum perturbations represent a system which is very similar to systems found in quantum optics. He also pointed out the limitations of this approach and investigated whether the large squeezing of the perturbations can allow us to observe a genuine observational signature in the sky of the quantum origin of the cosmological fluctuations.

Hendrik Ulbricht of the University of Southampton, UK, presented recent results on manipulation of levitated optomechanics for tests of fundamental physics, in particular the trapping and cooling experiments of optically levitated nanoparticles. The cooling of all translational motional degrees of freedom of a single trapped silica particle to ~1mK simultaneously at vacuum of 10-5 mbar using a parabolic mirror to form the optical trap were reported, together with the squeezing of a thermal motional state of the trapped particle by rapid switch of the trap frequency. Such experiments are relevant to pave the way towards an experimental test of both the quantum superposition principle and the interplay between gravity and quantum mechanics.

Towards a platform for macroscopic quantum experiments in space, was the subject discussed by Rainer Kaltenbaek of University of Vienna, Vienna Center for Quantum Science and Technology, Faculty of Physics, Austria. Recent developments have rendered space an increasingly attractive platform for quantum-enhanced sensing and for fundamental tests of physics using quantum technology. In particular, there already have been significant efforts towards realizing atom interferometry and atomic clocks in space as well as efforts to harness space as an environment for fundamental tests of physics using quantum optomechanics and high-mass matter-wave interferometry. Rainer presented recent efforts in mission planning, spacecraft design and technology development towards this latter goal in the context of the mission proposal MAQRO and ESA's recent call for New Science Ideas.

Yaakov Fein of the University of Vienna, Austria, discussed the progress at LUMI: the Long Baseline Universal Matter-Wave. At LUMI a Kapitza-Dirac-Talbot-Lau interferometer scheme with a one-meter grating separation is exploited. The aim is to detect interference at a mass scale beyond 100,000 amu, as well as to investigate massive and complex biomolecules, including bounds which can be placed on (certain) spontaneous collapse models.

Mauro Paternostro of CTAMOP, Queen's University Belfast, Ireland, introduced the entanglement between masses as a probe of the quantum nature of gravity. Interactions between two material objects are mediated by fields. If quantum entanglement is created between two such objects due to their interaction, then it follows that the "mediating" field must have been a quantum entity. Mauro first showed that the states of two micron dimension test masses in adjacent matter-wave interferometers could be detectably entangled solely through their mutual gravitational interaction. Then he argued that the purely gravitational mechanism for this entanglement implies that witnessing it is equivalent to certifying the quantum nature of the gravitational field that mediates the entanglement.

The workshop testifies that we are moving from a fruitful present in Quantum Foundation towards an even more exciting future: not only for a better understanding of the quantum universe we live in, but also to set the basis for future quantum technologies on earth and in space.

More information, including the files of the various presentations, can be found on the workshop dedicated web-page.


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Wandering Towards a Goal: Winners Announcement
By BRENDAN FOSTER • Jul. 4, 2017 @ 13:08 GMT

We asked the question: how do mindless mathematical laws give rise to aims and intentions. So how does it happen? Well, we’re not going to just tell you the answer. You’ll have to read it for yourself — in our winning essays, which we are now happy to announce!

We have an unusual outcome this time. Perhaps unsurprisingly, the contest question turns out to be rather controversial, with not just the essayists but also the panelists holding quite diverging views. Despite a lot of effort and good-faith attempts to find common ground, in the end the jury was deadlocked along several dimensions. In the end they decided the fairest representation of their collective opinions would be — a tie for first (and second) place. In fact, a 3-way tie.

Sharing the top spot are the entries from Larissa Albantakis (A Tale of Two Animats), Carlo Rovelli (Meaning and Intentionality = Information + Evolution), and Jochen Szangolies (Von Neumann Minds). The panel elected to pool the prize money for the top 3 spots, a total of $20,000, and split it evenly. Thus each of our 3 top winners will receive $6,666.

Visit our page of winners to also see our third and fourth prize winners, and find links to each winning essay. Also awarded was a special “community choice” award for the entry from George Ellis (Wandering Towards a Goal), which was well liked by many and, thanks to George’s involvement, had high levels of community engagement and forum interaction, which is a lot of what makes these contests worthwhile.

We look forward to our next contest, which we hope to announce soon.

Thanks to our sponsors, The Peter and Patricia Gruber Foundation, for making it possible. We also thank our diligent review panel. And last of all, we give great thanks to all of our entrants — we appreciate the effort you put into writing the entries, as well as reading and discussing them. We hope you will join us again for the next one.
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