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Please also note that we do not accept unsolicited posts and we cannot review, or open new threads for, unsolicited articles or papers. Requests to review or post such materials will not be answered. If you have your own novel physics theory or model, which you would like to post for further discussion among then FQXi community, then please add them directly to the "Alternative Models of Reality" thread, or to the "Alternative Models of Cosmology" thread. Thank you.

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Joe Fisher: "Georgina, as there am only one single VISIBLE infinite surface eternally..." in Why This Universe?

Georgina Woodward: "Joe, the appearance depends upon the sensory system of the observer..." in Why This Universe?

kurt stocklmeir: "gravity associated with gas and gas running into stars can change orbit of..." in Alternative Models of...

Patrik Miertviezky: "Hello everybody! My name is Patrik and i am 26 years old girl from Europe...." in Time in Physics & Entropy...

Rachelle Marie: "The lengthy form of the meeting, available on the page, you can similarly..." in Podcast Up: Interacting...

jhon dwayne: "If any customer face problem during window installing then he can call our..." in Manipulating the Quantum...

jhon dwayne: "If any customer face problem during window installing then he can call our..." in Manipulating the Quantum...

kurt stocklmeir: "there is a lot of gas between galaxies - there are a lot of small galaxies..." in Alternative Models of...

click titles to read articles

Fuzzballs v Black Holes
A radical theory replaces the cosmic crunchers with fuzzy quantum spheres, potentially solving the black-hole information paradox and explaining away the Big Bang and the origin of time.

Whose Physics Is It Anyway? Q&A with Chanda Prescod-Weinstein
Why physics and astronomy communities must take diversity issues seriously in order to do good science.

Why Time Might Not Be an Illusion
Einstein’s relativity pushes physicists towards a picture of the universe as a block, in which the past, present, and future all exist on the same footing; but maybe that shift in thinking has gone too far.

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

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

June 23, 2018

New Blog Entries
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New Online Course: Algorithmic Information Dynamics
By HECTOR ZENIL • May. 18, 2018 @ 19:54 GMT

Supported by the Foundational Questions Institute, a new MOOC (massive open online course) on the new and exciting field of "Algorithmic Information Dynamics" will be released on June 12ve by the Santa Fe Institute. The course offers a novel computational perspective to causality and living systems, from complex networks to reprogramming cells. You are all welcome to sign up for the course, for a small fee with access to certificate and materials, or to watch it for free.

You can learn more about the MOOC from this brief introductory video:

Harnessing the power of computational models:

Probability and statistics have long helped scientists make sense of data about the natural world — to find meaningful signals in the noise. But classical statistics prove a little threadbare in today’s landscape of large datasets, which are driving new insights in disciplines ranging from biology to ecology to economics. It's as true in biology, with the advent of genome sequencing, as it is in astronomy, with telescope surveys charting the entire sky. The data have changed.

Algorithmic Information Dynamics is an exciting new field put forward by our lab based upon some of the most mathematically mature and powerful theories put together in harmony to tackle some of the challenges of causal discovery from a heavily model-driven and mechanistic perspective.

Taught by me and my friend and colleague Dr. Narsis A. Kiani, co-leaders of the Algorithmic Dynamics Lab, the course will provide a conceptual introduction to the field focusing on mathematical and computational aspects in the study of causality. The course covers key aspects from graph theory and network science, information theory, dynamical systems and algorithmic complexity. It will venture into ongoing research in fundamental science and its applications to behavioral, evolutionary and molecular biology.

After a conceptual overview of the main motivation and some historical developments, we will review some preliminary aspects needed to understand the most advanced topics. These include basic concepts of statistics and probability, notions of computability and algorithmic complexity and brief introductions to graph theory and dynamical systems. We then dig deeper into the core of the course, that of Algorithmic Information Dynamics which brings all these areas together in harmony to serve in the challenge of causality discovery, the most important topic in science. Central to the course and the field is the theory of algorithmic probability that establishes a formal bridge between computation, complexity and probability.

Finally, we move towards new measures and tools related to reprogramming artificial and biological systems, applications to biological evolution, evolutionary programming, phase space and space-time reconstruction, epigenetic landscapes and aspects relevant to data analytics and machine learning such as model generation, feature selection, dimensionality reduction and causal deconvolution. We will showcase the tools and framework in applications to behavioral, evolutionary and molecular biology, in particular genetic networks.


1. A Computational Approach to Causality

2. Technical Skills and Selected Topics

3. A Brief Introduction to Graph Theory and Biological Networks

4. Basics of Computability, Information Theory and Algorithmic Complexity

5. Dynamical Systems as Models of the World

6. Foundations of Algorithmic Information Dynamics and Reprogrammability

7. Applications to Behavioural, Evolutionary and Molecular Biology

Tuition is $50, which is required to get to the course material during the course and a certificate at the end. But the course will also be made available free to watch and if no fee is paid materials will not be available until the course closes. Donations are highly encouraged and appreciated in support for SFI's ComplexityExplorer to continue offering new courses.

In addition to all course materials tuition includes:

• Six-month access to the Wolfram|One platform (renewable for other six)

• Free digital copy of the course textbook to be published by Cambridge University Press

• Several gifts will be given away to the top students finishing the course, check the FAQ page for more details.

You can register yourself at here.

We look forward to you doing us!

Hector Zenil is co-leader of the Algorithmic Dynamics Lab, and a member of FQXi.
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What Is Fundamental? – Winners Roll
By BRENDAN FOSTER • May. 14, 2018 @ 16:02 GMT

Rho Ophiuchus Photo By Rogelio Bernal Andreo -
There may be no better question for FQXi to ask then, What Is “Fundamental”? We asked this question last October for our latest essay contest, and over 200 deep-thinkers sent us their ideas.

You might agree with what they have said, or you might not.

It is now time to reveal all the answers! — or, I mean, reveal all the winners.

Let me first thank our sponsors, for making the contest possible. The Peter and Patricia Gruber Foundation have long been a great help, and The Fetzer Franklin Fund has joined us in our ongoing Agency in the Physical World program. Thanks also to our panel of judges for their diligence. And thank you to all of you who took the time to answer our question and write us an essay.

Here we go with the winners, to be revealed as the day goes on. You can follow along as well, on Twitter, @FQXi —

This year we have two special prizes to announce.

An award for Creative Writing ($1,000) goes to Mozibur Ullah and his dialogue, Socrates, Atoms, and Being.

And an award for a Student Author ($1,000) goes to Aditya Dwarkesh, for ’Fundamentality' as a Linguistic Paradigm (and Linguistics as a Fundamental Paradigm).

Next, we have our Fourth Prize Winners. These will all receive $1,000. In first-name alphabetical order, we have:

Ian Durham, Bell's Theory of Beables and the Concept of ‘Universe'

Ken Wharton, Fundamental Is Non-Random

Marc Séguin, Fundamentality Here, Fundamentality There, Fundamentality Everywhere

Markus Mueller, Mind Before Matter: Reversing the Arrow of Fundamentality

Tejinder Singh, Things, Laws, and the Human Mind

Next, we have the Third Prize Winners. Each essay will receive $2,000. We have:

Gregory Derry, Fundamentality, Explanation, and the Unity of Science

Karen Crowther, When do we stop digging? Conditions on a fundamental theory of physics

Sabine Hossenfelder, The Case for Strong Emergence

Sean Carroll and Ashmeet Singh, Mad-Dog Everettianism: Quantum Mechanics at Its Most Minimal.

And now, for our Second Prize Winners. Our panel felt that each of these was all-around excellent quality, and chose to award each one a full $5,000. We have:

Alyssa Ney, The Politics of Fundamentality

Dean Rickles, Of Lego and Layers (and Fundamentalism)

Matt Leifer, Against Fundamentalism.

And now finally, we have our top winner. Last year, you may recall our panel could not decide between three essays for first. This year, they unanimously agreed on one entry. We are pleased to award the $10,000 First Prize to:

Emily Adlam, Fundamental?

Congratulations to all our winners. Here’s looking forward to the next contest. On behalf of FQXi, thanks to all of you for reading along.
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Cosmic Dawn, Parallel Observers, and a Science Hostel in Maui: New Podcast
By ZEEYA MERALI • Mar. 21, 2018 @ 20:04 GMT

EDGES antenna, by Suzyj, Wikicommons
This month’s podcast features the exciting discovery of signs of the first stars made by astronomers using the EDGES experiment, in Western Australia (right), published in Nature, in February. It’s long been predicted that they should see such an indirect signal, which they picked up as a dip in the intensity of radiation in the cosmic microwave background (the afterglow of the big bang). But while this signal was where they thought it would be, and confirmed when they thought the first stars appeared — some 180 million years after the big bang — the detection raised new puzzles. The signal was far stronger than had been predicted. So, I spoke with cosmologist Rennan Barkana, of Tel Aviv University in Israel, who published a companion paper in the same edition of Nature, offering a possible solution: the boosted signal could be caused by an unexpected interaction with dark matter, in the early universe.

Free Podcast

Remembering Stephen Hawking; light from the first stars in the universe, with Rennan Barkana; our place in the multiverse, with Eugene Lim; & setting up a science hostel in Maui, with Garrett Lisi.


Go to full podcast

Next, reporter Sophie Hebden chatted to cosmologist Eugene Lim, of King’s College London, about what we may be able to infer about observers in parallel universes. Lim, and his colleague Richard Easther, at the University of Auckland, are examining the possibility that we live in a multiverse of neighbouring cosmoses that each have different physical laws. But how likely is it that sentient observers will arise in those regions? What are the minimal set of physical properties needed for such observers to evolve? And what might our multiversal neighbours be able to measure? Answering such questions might help explain why our universe has the peculiar rules that it does. (You can read more about Lim and Easther’s work in Sophie's article, "Our Place in the Multiverse.")

And, if you're wondering what we do when we're not podcasting, the answer, for Brendan Foster at least, is he enjoys relaxing in Maui. But on this holiday, he took some time to meet with theoretical physicist Garrett Lisi, who has opened a hostel for scientists to visit and spend time working. Listen now to hear Brendan’s verdict on whether staying in such an idyllic location can be productive for research.

Finally, we've been away for a while. In the meantime, we saw the sad passing of two giants of theoretical physics, Joe Polchinski and Stephen Hawking. The latter died after we recorded the main edition, but we've added a few words to commemorate these huge losses. Both shall be missed.
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Remembering Stephen W. Hawking (1942-2018)
By DON PAGE • Mar. 19, 2018 @ 15:46 GMT

Stephen Hawking was the greatest theoretical gravitational physicist since Einstein. Using the assumptions of Einstein's classical theory of gravity, general relativity, plus reasonable conditions on the energy density and pressure of matter, Hawking showed that the observed expansion of the universe would imply that the universe had a beginning, a big bang singularity at the beginning of time. Under similar assumptions, he showed that the surface of a black hole, called the event horizon, would have an area that cannot decrease with time but could only stay the same (if nothing fell into the black hole) or get bigger (if energy did fall into the hole).

Later, Hawking turned his attention to quantum theory, which can lead to violations of the usual reasonable conditions on the energy density and pressure of matter. He then found that actually black holes can create and emit particles, now called Hawking radiation, and shrink, presumably eventually disappearing entirely into a final burst of radiation.

This prediction of Hawking radiation is perhaps Hawking's most well known discovery, and it has almost entirely been accepted by other physicists who have studied the situation of a black hole with negligible incoming energy. However, this 1974 discovery led Hawking in 1976 to make the more radical proposal that when a black hole forms and then evaporates away, information is lost from our universe. (In more technical terms, a pure quantum state would become a mixed quantum state, with greater von Neumann entropy.)

Starting with a paper of mine in 1980 that questioned Hawking's argument for information loss and with a very small number of other papers on this in the early years, a growing crescendo of papers have appeared on black hole information. Eventually, particularly as a result of string theory arguments, the majority of papers have questioned information loss and supported the older view that information is not lost. In 2004, Hawking reversed his opinion and conceded a famous bet he had made in 1997 with John Preskill. In 2007, Hawking conceded an even earlier bet he had made with me in 1980, paying me a dollar that was actually a fake dollar with a picture of Marilyn Monroe, whom he considered to be "a model of the universe." However, there are several renowned physicists who think Hawking was originally correct and should not have conceded his bets.

Hawking also applied quantum theory to the universe and, with James Hartle of the University of California at Santa Barbara in 1983, proposed the no-boundary wave function of the universe. This was conceptually a major innovation, proposing laws of physics not only for how the universe evolves but what it was like at some initial time. The Hartle-Hawking no-boundary quantum state pictures the universe as not having a singular beginning and in some sense no beginning at any precise time at all, thereby giving a different picture than the singular beginning proved by his singularity theorems under the approximation of classical general relativity. However, one should note that it is almost certainly premature to give a precise quantum state for the universe, and indeed there are some technical problems with the Hartle-Hawking proposal. Nevertheless, it is a major conceptual advance to bring the quantum state within the laws of physics.

These are just a few of the highlights of the remarkable achievements Hawking has achieved in physics. Besides his academic work, he has done a great service in popularizing his and other advances in physics and cosmology with books such as the bestseller, A Brief History of Time. His courage in the face of enormous physical adversity has also been an inspiration to millions of people.

On a personal note, Stephen Hawking was an outstanding mentor for me, from being a co-supervisor (along with my main supervisor Kip Thorne) of my Ph.D. during his 1974-75 visit to Caltech and during my postdoctoral position under his supervision at the University of Cambridge 1976-79. He has indeed been crucial in my career, both in getting me my academic positions and in giving me plenty of ideas that I have continued to work on throughout my career. He and his family were also very close personal friends (going back to my living in his home and helping him out while being a postdoc in Cambridge). I shall miss him greatly.

Don Page is a theoretical physicist at the University of Alberta, Edmonton. He and his wife Cathy Page have also paid tribute to the late Stephen Hawking on CBC’s Calgary Explorer, Edmonton AM, and “Quirks and Quarks.”
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Stephen Hawking (1942-2018)
By ZEEYA MERALI • Mar. 14, 2018 @ 14:32 GMT

Credit: NASA
Many of you have woken to the sad news of the passing of Stephen Hawking — a towering figure in theoretical physics and cosmology, who inspired so many within science and beyond, with his intellectual insights into the nature of the universe, his wit, and his zest for the life that doctors once told him he would never have.

It’s difficult to overstate Hawking’s influence on the physics community. Roger Penrose, writing in the Guardian, and Martin Rees, in Nature, have written extremely accessible descriptions of the impact of his work. In the 1960s, with Penrose, George Ellis, and others, Hawking’s calculations helped to elucidate the mathematics of how the big bang marks the beginning of not just space, but time itself, from an infinitely small, dense “singularity.” Such singularities represent the breakdown of our best theories of physics and are also thought to lie at the heart of black holes, shrouded by an event horizon. It was believed that these event horizons act as one-way membranes that allow nothing that passes, not even light, to escape a black hole’s clutches. But, in the 1970s, Hawking’s work examining black holes with both general relativity and quantum theory, led him to propose that black holes can, in fact, slowly radiate particles, through the process of what has become known as “Hawking radiation.” This, in turn, suggests that black holes will slowly evaporate away — raising profound puzzles over the fate of information about the objects that fell in to the black hole.

This black-hole information paradox has yet to be resolved to everyone’s satisfaction; in fact, in recent years it has only become more confounding. But, as is often the way in science, posing questions can sometimes be as fruitful as offering solutions — and researchers are using this paradox, and its offshoots, as a handle to try to understand which of the two cornerstones of physics, Einstein’s general theory of relativity or quantum theory, has to give. Many FQXi members are today absorbed in projects that have their roots in Hawking’s work.

But Hawking’s influence goes deeper. As the bestselling author of A Brief History of Time, he directly inspired so many of us to study physics and cosmology, in the first place. I’ve lost count of the number of FQXi members who cite reading the book as a defining moment in their lives. I myself read natural sciences at Cambridge University, where Hawking was based and held the Lucasian Chair of Mathematics for many years. My fellow students and I never ceased to be excited to hear Hawking, or bump into him on the streets (quite literally, in the case of a friend, whom I recall returning to college one afternoon in a flustered state because she had cycled into his wheelchair). And while there might have been a danger that his celebrity status would give him an aura of unapproachability, he undercut this with his humour and the twinkle in his eyes. Hawking laced his public talks with jokes, managing to display comic timing despite speaking through a voice synthesiser. I personally loved him playfully claiming that the Spice Girls were his favourite group, for instance (or possibly that was entirely sincere, I’m not sure).

Later, as a science journalist, I was honoured that Hawking agreed to be interviewed by me for New Scientist and Nature, both about his own work, and to give his thoughts on that of others, even though providing comments clearly took a physical toll. But, of course, in addition to his scientific accomplishments, he will be remembered and admired for his commitment to engage the public and his refusal to be defined by the motor-neurone disease that struck him at just 21 years of age. That legacy will remain for generations to come.

Our thoughts at FQXi are with Hawking’s family, friends, and colleagues.
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