Search FQXi


RECENT FORUM POSTS

Georgina Woodward: "'Sharp comb" and 'shredder' are used as similes and metaphors because the..." in Schrödinger’s Zombie:...

Sydney Grimm: "Lorraine, Let’s take an example: E= mc[sup]2[/sup]. It is an equation..." in Measuring Free Will: Ian...

Jason Wolfe: "I cannot say that I am enthusiastic about where philosophy has led us. We..." in The Demon in the Machine...

Jason Wolfe: "How can there be any talk of determinism when the real world is built upon..." in Measuring Free Will: Ian...

Georgina Woodward: "I might be able to improve on that description. It's early days.If it is a..." in Schrödinger’s Zombie:...

Robert McEachern: ""do you agree with Davies that these questions will need new physics?" It..." in The Demon in the Machine...

Zeeya Merali: "Joe, You appear to really want to contact Dr Kuhn about his Closer to..." in First Things First: The...

Joe Fisher: "(Zeeya's note: Joe I've deleted the text of this post. It appears to be..." in First Things First: The...


RECENT ARTICLES
click titles to read articles

First Things First: The Physics of Causality
Why do we remember the past and not the future? Untangling the connections between cause and effect, choice, and entropy.

Can Time Be Saved From Physics?
Philosophers, physicists and neuroscientists discuss how our sense of time’s flow might arise through our interactions with external stimuli—despite suggestions from Einstein's relativity that our perception of the passage of time is an illusion.

Thermo-Demonics
A devilish new framework of thermodynamics that focuses on how we observe information could help illuminate our understanding of probability and rewrite quantum theory.

Gravity's Residue
An unusual approach to unifying the laws of physics could solve Hawking's black-hole information paradox—and its predicted gravitational "memory effect" could be picked up by LIGO.

Could Mind Forge the Universe?
Objective reality, and the laws of physics themselves, emerge from our observations, according to a new framework that turns what we think of as fundamental on its head.


FQXI ARTICLE
September 21, 2019

Thermo-Demonics
A devilish new framework of thermodynamics, which focuses on how we observe information, could help illuminate our understanding of probability and rewrite quantum theory.
by M. Mitchell Waldrop
March 4, 2019
Bookmark and Share


Michel Westmoreland & Benjamin Schumacher
Playfully dubbed ’Thermo-Demonics,’ a new approach to physics that focuses on the meaning of observation could bring new insights to thermodynamics, the science of heat, and quantum theory, the set of laws that govern the microrealm.

The framework, which is being developed by physicist Benjamin Schumacher, at Kenyon College in Gambier, Ohio, and mathematician Michael Westmoreland, at Denison University in Granville, Ohio, was given this devilish moniker by their colleagues because it put information at the center—along with a hypothetical, microscopic observer known as Maxwell’s demon. With the help of an FQXi grant of over $70,000, Schumacher and Westmoreland hope it will also enable them to remove the confusion over measurement and uncertainty in quantum theory.

Schumacher and Westmoreland realised they were kindred spirits in the 1990s. Both were interested in how information theory could help illuminate quantum mechanics and began to collaborate. In the quantum realm, observers typically know very little about where a particle is, or how fast it is moving, or how it is spinning. They have to make a measurement to reduce that uncertainty. In information theory, likewise, the information you gain when you learn something about a system is mathematically defined to be the reduction in your uncertainty about it. If you have a single ASCII character, for example, but only know that it is alphanumeric, there are 62 possibilities: 26 lowercase letters + 26 uppercase letters + 10 digits. But once you learn that the character is, say, F, you reduce the uncertainty from 62 to 1, and gain a corresponding amount of information.

I started wondering
if information is
more fundamental
than probabilities.
- Michael Westmoreland
At the same time, however, quantum theory contains a mystery that has haunted physicists since its development in the 1920s. All the quantum uncertainty about a system is encoded in its wavefunction: a mathematical entity that evolves with time in a perfectly predictable manner—so long as you leave it alone. But the instant you make that measurement, the wavefunction collapses into one possibility or another—and there is no predicting with certainty which one. All you can know in advance is the probability of obtaining a given outcome.

Making sense of this measurement problem is the "most fundamental problem in all of quantum mechanics," says William Wootters, a physicist at Williams College in Williamstown, Massachusetts, and a pioneer of quantum information theory.

Schumacher and Westmoreland have taken on that challenge. By the mid-2000s, they were trying to codify their work and that of many others in an undergraduate textbook on quantum mechanics from an information point of view (Quantum Processes, Systems, and Information (2010)). "In the process of writing," says Westmoreland, "I started wondering if information is more fundamental than probabilities."

That question led the two researchers to start thinking harder about the physics of the observer. They formulated the notion of an ’eidostate’—"a description of the world that exists as a physical state, and in which changes involve physical processes," says Schumacher. (The name comes from the Greek word ’eidos’ meaning "to see.")


Maxwell’s Demon
By choosing when to open and close the door, the demon causes one chamber to warm
up and the other to cool.

Credit: Htkym, Wikicommons
They decided to test the usefulness of eidostates by first applying them to thermodynamics—a branch of physics that also deals with deep limits on what observers can know. Their starting point was a conundrum originally pointed out in 1867, when the Scottish physicist James Clerk Maxwell proposed the following thought experiment: Imagine that a sample of gas is contained in a box that is divided down the middle by a partition. Imagine further that there is a trap door in the partition operated by a tiny being "whose faculties are so sharpened that he can follow every molecule in its course." If the being saw a high-energy molecule approaching the partition from, say, the left half of the box, it could briefly open the trap door to let that molecule pass through to the right side. And likewise, it could let low energy molecules pass through from right to left. Over time, Maxwell argued, the average energy, and thus the temperature, would increase on the right and decrease on the left. Or to put it another way, the being could cause heat to spontaneously flow from cold to hot—a violation of the Second Law of Thermodynamics, which says that heat will spontaneously flow only from hot to cold, and not vice versa.

Maxwell left this paradox to later generations of physicists as a kind of homework assignment: Where was the flaw in this thought experiment? What would keep Maxwell’s ’demon’, as other physicists took to calling it, from violating the second law? Did the demon’s ability to observe, think, and act change the fundamental physics in some way? Or was its ’intelligence’ still governed by natural law?

Information Erasure

The solution that’s most widely accepted was given in 1982 by IBM physicist Charles Bennett, who based it on work that the late IBM physicist Rolf Landauer published in 1960. Yes, Bennett argued, a demon could, in theory, create an apparent violation of the second law through a completely automated process that required no intelligence whatsoever—but only if it retained information about every interaction with every molecule it had ever encountered. Once it started erasing that information, as any finite automata would eventually have to do, it would release energy back into the environment at exactly the rate (prescribed by ’Landauer’s principle’) required to preserve the second law.

A lot of physicists took Landauer’s minimum energy limit as a challenge, and immediately started pointing out special situations where it could be violated, notes Bennett. To clarify the resulting confusion, Schumacher and Westmoreland reworked Landauer’s principle into an elegantly simple formulation of the second law that took all the exceptions into account: No physical process can have as its sole result the erasure of information. Then they used their eidostate concept to do a careful analysis of the physics of observers, be they macroscopic humans in the lab, or microscopic demons.


Human or Demon?
A thermodynamic price is always paid when observers, of any form, process information
and act on it.

Credit: LPETTET, istock
Bennett vividly remembers first hearing about the new formulation in 2013, when Schumacher gave a talk at the Institute for Quantum Computing, in Waterloo, Ontario. Schumacher showed that "all the exceptions weren’t real, just apparent," says Bennett, because they all involved some kind of external change in, say, energy—precisely what the new formulation ruled out.

Schumacher’s words "had a very salutary effect," recalls Bennett. He notes that Schumacher and Westmoreland, who are both at smaller schools that emphasize teaching, had simplified elements of thermodynamics—"just the way it should be in a textbook."

Since then, Schumacher and Westmoreland have expanded that insight. "What we find is that a few very simple axioms about information can serve as a foundation for thermodynamics," says Schumacher, "including some things we didn’t expect." For example, the axioms contain no notion of probability, but they were able to derive a notion of probability from them (A. Hulse, B. Schumacher & M. D. Westmoreland, Entropy 201820(4), 237).

Quantum theory is next in their sights. Eidostates should be well suited to the task, says Westmoreland because "they’re built to accommodate indeterminacy."

They are as eager as anyone to see where that will lead. "Understanding quantum mechanics is no mean feat—we haven’t done it yet!" says Wootters. "It may be that in order to get there, we’ll have to completely reframe the theory." If that’s the case, he says, "this particular point of view that Ben and Mike are taking might help us see our way to whatever comes next."

Comment on this Article

Please read the important Introduction that governs your participation in this community. Inappropriate language will not be tolerated and posts containing such language will be deleted. Otherwise, this is a free speech Forum and all are welcome!
  • Please enter the text of your post, then click the "Submit New Post" button below. You may also optionally add file attachments below before submitting your edits.

  • HTML tags are not permitted in posts, and will automatically be stripped out. Links to other web sites are permitted. For instructions on how to add links, please read the link help page.

  • You may use superscript (10100) and subscript (A2) using [sup]...[/sup] and [sub]...[/sub] tags.

  • You may use bold (important) and italics (emphasize) using [b]...[/b] and [i]...[/i] tags.

  • You may also include LateX equations into your post.

Insert LaTeX Equation [hide]

LaTeX equations may be displayed in FQXi Forum posts by including them within [equation]...[/equation] tags. You may type your equation directly into your post, or use the LaTeX Equation Preview feature below to see how your equation will render (this is recommended).

For more help on LaTeX, please see the LaTeX Project Home Page.

LaTeX Equation Preview



preview equation
clear equation
insert equation into post at cursor


Your name: (optional)






Recent Comments


good job. you can try to http://Pokersilang.com/


If you have gotten curious from the results of a spherical condensate and have played with a little reverse engineering (and aren't afraid of argumentation in pure mathematics) but ran into a problem getting duplicate results, it is likely that is because electronic calculators and calculation programs are engineered at the microprocessor level to NOT do certain functions. Everyone is familiar with entering X divided by zero and getting a display result that says 'error'. Same way with...


One final note; If you look at Coulomb's Law it is a derivative of inverse square law which as with SR is an invariance function. Invariably, 1/r^2 will obtain in measurement from A to B, OR (but not and) B to A. A & B are seperate inertially bound objects. But in a single inertially bound field, that relationship is covariant to the upper density bound, A & B are different magnitudes of density in the same field and vary by the inverse of exponential rate, (1/e). Ineractive fields in regions of...

read all article comments

Please enter your e-mail address:
Note: Joining the FQXi mailing list does not give you a login account or constitute membership in the organization.