Brain Behind Einstein's Famous Equation

ScienceDaily reports:

Jan. 25, 2013 — A new study reveals the contribution of a little known Austrian physicist, Friedrich Hasenöhrl, to uncovering a precursor to Einstein famous equation.

A new study reveals the contribution of a little known Austrian physicist, Friedrich Hasenöhrl, to uncovering a precursor to Einstein famous equation.

Two American physicists outline the role played by Austrian physicist Friedrich Hasenöhrl in establishing the proportionality between the energy (E) of a quantity of matter with its mass (m) in a cavity filled with radiation. In a paper about to be published in the European Physical Journal H, Stephen Boughn from Haverford College in Pensylvannia and Tony Rothman from Princeton University in New Jersey argue how Hasenöhrl's work, for which he now receives little credit, may have contributed to the famous equation E=mc².

According to science philosopher Thomas Kuhn, the nature of scientific progress occurs through paradigm shifts, which depend on the cultural and historical circumstances of groups of scientists. Concurring with this idea, the authors believe the notion that mass and energy should be related did not originate solely with Hasenöhrl. Nor did it suddenly emerge in 1905, when Einstein published his paper, as popular mythology would have it.

Given the lack of recognition for Hasenöhrl's contribution, the authors examined the Austrian physicist's original work on blackbody radiation in a cavity with perfectly reflective walls. This study seeks to identify the blackbody's mass changes when the cavity is moving relative to the observer.

They then explored the reason why the Austrian physicist arrived at an energy/mass correlation with the wrong factor, namely at the equation: E = (3/8) mc². Hasenöhrl's error, they believe, stems from failing to account for the mass lost by the blackbody while radiating.

Before Hasenöhrl focused on cavity radiation, other physicists, including French mathematician Henri Poincaré and German physicist Max Abraham, showed the existence of an inertial mass associated with electromagnetic energy. In 1905, Einstein gave the correct relationship between inertial mass and electromagnetic energy, E=mc². Nevertheless, it was not until 1911 that German physicist Max von Laue generalised it to include all forms of energy.

I reported on this paper in Aug. 2011 here and here, with a link to an English translation of Hasenöhrl's 1904 paper.

None of this supports Kuhnian paradigm shifts. Kuhn defined such a shift as an irrational change of viewpoint with no measurable evidence. (Kuhn preferred the terms arational and incommensurable.) The relation between relativistic mass and energy was first predicted by Lorentz in 1899, and experimentally tested in 1902.

Poincare's conventionalism

Henri Poincare was the leading mathematical physicist of 1900. Besides discovering relativity, he had a big impact on the philosophy of science. Here are a couple of new papers on him.

Poincare's impact on 20th century philosophy of science:

Poincaré’s conventionalism has thoroughly transformed both the philosophy of science and the philosophy of mathematics. Not only proponents of conventionalism, such as the logical positivists, were influenced by Poincaré, but also outspoken critics of conventionalism, such as Quine and Putnam, were inspired by his daring position. Indeed, during the twentieth century, most philosophers of mathematics and of science engaged in dialogue with conventionalism. As is often the case with such complex clusters of ideas, there is no consensus about the meaning of conventionalism in general, and Poincaré’s original version of it, in particular. Nonetheless, notions such as the under-determination (of theory), empirical equivalence (of incompatible theories), implicit definition, holism and conceptual relativity, all of which can be linked to Poincare's writings (even if not under those very names) have become central to philosophy. This essay explores the impact of some of these notions on twentieth century philosophy of science. In addition to inspiration based on Poincare's actual views, it emphasizes directions based on misreading and unjustified appropriations of Poincaré.

Did Perrin's experiments convert Poincaré to Scientific Realism?

In this paper I argue that Poincaré’s acceptance of the atom does not indicate a shift from instrumentalism to scientific realism. I examine the implications of Poincaré’s acceptance of the existence of the atom for our current understanding of his philosophy of science. Specifically, how can we understand Poincaré’s acceptance of the atom in structural realist terms? I examine his 1912 paper carefully and suggest that it does not entail scientific realism in the sense of acceptance of the fundamental existence of atoms but rather, argues against fundamental entities. I argue that Poincaré’s paper motivates a non-fundamentalist view about the world, and that this is compatible with his structuralism.

String theory comic

The guy in the comic resembles Ed Witten.

Explaining quantum observers

Lumo explains quantum mechanics again:

I am writing down this preposterous story because this is exactly the type of thinking that many popular – and, using Sidney Coleman's words, sometimes even not-so-popular – books and articles want you to manipulate you into. GRW and Penrose collapse theories as well as the many-worlds ideology are example models giving special objects the right to "intervene" into Schrödinger's equation, either by discontinuous jumps or collapses or by splitting the world (which is comparably, infinitely ambitious). However, all this reasoning is completely nonsensical. There doesn't exist any systems for which the evolution according to the laws of quantum mechanics such as Schrödinger's equation is replaced by some discontinuous jumps. Quantum mechanics applies to all systems and processes in Nature, regardless of their size, duration, sex, race, and nationality. ...

Needless to say, people are looking for an "objective classical model of reality" that is valid for everyone. But quantum mechanics shows that Nature can't be described in this way. Instead, quantum mechanics tells you that you must understand yourself as an observer who may perceive the values of certain observables and quantum mechanics tells you that observing some values of observables at one moment implies that the probability of observing some combination of other observables at a different moment is something or something else. That's the only thing you may really empirically verify so it's just unphysical to "demand" that science also explains something else (such as an "underlying objective reality").

He is right. As you can see from my slogan, I do not believe in discontinuous jumps. Belief in hidden variables and jumps is misguided.

Sean M. Carroll writes about the poll I posted last week:

I’ll go out on a limb to suggest that the results of this poll should be very embarrassing to physicists. Not, I hasten to add, because Copenhagen came in first, although that’s also a perspective I might want to defend (I think Copenhagen is completely ill-defined, and shouldn’t be the favorite anything of any thoughtful person). The embarrassing thing is that we don’t have agreement.

Think about it — quantum mechanics has been around since the 1920's at least, in a fairly settled form. John von Neumann laid out the mathematical structure in 1932. Subsequently, quantum mechanics has become the most important and best-tested part of modern physics. Without it, nothing makes sense. Every student who gets a degree in physics is supposed to learn QM above all else. There are a variety of experimental probes, all of which confirm the theory to spectacular precision.

And yet — we don’t understand it. Embarrassing. To all of us, as a field (not excepting myself).

I’m sitting in a bistro at the University of Nottingham, where I gave a talk yesterday about quantum mechanics. I put it this way: here in 2013, we don’t really know whether objective “wave function collapse” is part of reality (as the poll above demonstrates).

Lumo rips him for these silly comments, but I think that it is embarrassing that so many physicists like Carroll do not seem to understand what von Neumann elucidated in 1932.

Chad Orzel responds:

He dates this from John von Neumann laying out the mathematical foundations in 1932, which is a little ironic, because about thirty of those eighty years of inaction can be laid at von Neumann’s feet. When he laid out his formulation of quantum mechanics, von Neumann asserted that hidden-variable theories were ruled out mathematically, and his reputation was such that most physicists regarded this as a settled question on that basis. The problem is, he was flat wrong on this point, relying on a mathematical theorem that didn’t actually say what he claimed it did.

The question was eventually re-opened in part by people thinking about it the right way– in particular David Bohm, and then John Bell.

Von Neumann was right about there being no hidden variables. His theorem was maybe weaker than what some people realized, but the search by Bohm and others for hidden variable theories has been a theoretical and experimental failure.

What worries a physicist about the quantum

The Edge.org has its annual question for intellectuals. Lee Smolin writes:

But there is another possibility: that quantum mechanics does not provide an explanation for what happens in individual phenomena because it is incomplete, because it simply leaves out aspects of nature needed for a true description. This is what Einstein believed and it is also what de Broglie and Schroedinger, who made key steps formulating the theory, believed. This is what I believe and my lifelong worry has been how to discover that more complete theory.

A completion of quantum mechanics which allows a full description of individual phenomena is called a hidden variables theory. Several have been invented; one which has been much studied was invented by de Broglie in 1928 and reinvented by David Bohm in the 1950s. This shows its possible, now what we need to do is find the right theory. The best way to do that would be to discover a theory that agreed with all past tests of quantum mechanics but disagreed about the outcomes of experiments with large, complex quantum devices now under development.

We know that such a theory must be radically non-local, in the sense that once two particles interact and separate, their properties are entangled even if they travel far from each other. This implies that information as to the precise outcomes of experiments they may be each subject to has to be able to travel faster than light.

This means that a complete theory of quantum phenomena must contain a theory of space and time. As a result I've long believed that the task of completing quantum mechanics and the challenge of unifying quantum mechanics with spacetime are one and the same problem. I also see the problem of extending our understanding of physics at the cosmological scale to be the same as discovering the world behind quantum mechanics.

This belief in a theory of nonlocal hidden variables is irrational. There is not a shred of theoretical or experimental evidence for it. All attmpts at such a theories have been miserable failures.

Copenhagen interpretation did not demand realism

NewScientist explains strange new research in quantum physics, and concludes:

So, has Bohr been proved wrong too? Johannes Kofler of the Max Planck Institute of Quantum Optics in Garching, Germany, doesn't think so. "I'm really very, very sure that he would be perfectly fine with all these experiments," he says. The complementarity principle is at the heart of the "Copenhagen interpretation" of quantum mechanics, named after Bohr's home city, which essentially argues that we see a conflict in such results only because our minds, attuned as they are to a macroscopic, classically functioning cosmos, are not equipped to deal with the quantum world. "The Copenhagen interpretation, from the very beginning, didn't demand any 'realistic' world view of the quantum system," says Kofler.

The outcomes of the latest experiments simply bear that out. "Particle" and "wave" are concepts we latch on to because they seem to correspond to guises of matter in our familiar, classical world. But attempting to describe true quantum reality with these or any other black-or-white concepts is an enterprise doomed to failure.

It's a notion that takes us straight back into Plato's cave, says Ionicioiu. In the ancient Greek philosopher's allegory, prisoners shackled in a cave see only shadows of objects cast onto a cave wall, never the object itself. A cylinder, for example, might be seen as a rectangle or a circle, or anything in between. Something similar is happening with the basic building blocks of reality. "Sometimes the photon looks like a wave, sometimes like a particle, or like anything in between," says Ionicioiu. In reality, though, it is none of these things. What it is, though, we do not have the words or the concepts to express.

That's right. Physicists keep cooking up fancy terminology for quantum paradoxes, but the core strangeness is the same as what Bohr explained 80 years ago.

Paper says all probability is quantum

NewScientist reports:

WHY is there a 1 in 2 chance of getting a tail when you flip a coin? It may seem like a simple question, but the humble coin toss is now at the heart of a lively row about the multiverse. At stake is the ability to calculate which, of an infinite number of parallel universes, is the one that we inhabit.

The debate comes in the wake of a paper posted online a couple of weeks ago by cosmologists Andreas Albrecht and Daniel Phillips, both at the University of California, Davis. They argue that conventional probability theory, the tool we all use to quantify uncertainty in the real world, has no basis in reality (arxiv.org/abs/1212.0953). Instead, all problems in probability are ultimately about quantum mechanics. "Every single time we use probability successfully, that use actually comes from quantum mechanics," says Albrecht.

This controversial claim traces back to the uncertainty principle, which says that it is impossible to know both a quantum particle's exact position and its momentum.

Albrecht and Phillips think particle collisions within gases and liquids amplify this uncertainty to the scale of everyday objects. This, they say, is what drives all events, including the outcome of a coin toss. Conventional probability - which says the outcome simply arises from two equally likely possibilities - is just a useful proxy for measuring the underlying quantum uncertainties. ...

There is just one problem. The Born rule breaks down in some situations. The latest theories in cosmology say that our universe is just one part of a vast multiverse containing a large or even infinite number of other "pocket" universes. Some of those universes will be exact copies of our own, right down to a duplicate you. The mathematics behind the Born rule can't cope with this.

"In these situations, the quantum wave function can tell you nothing about which pocket you are in," says Albrecht. That's a problem if we want to predict the properties of our universe, which will look identical to many others at a given point in time, but which can eventually evolve differently due to quantum uncertainty.

Until now, physicists seeking to predict the properties and behaviour of the multiverse have added a sprinkling of conventional probability to reflect the chance of us being in a particular universe. For example, in a multiverse with just two universes, you might add a 50-50 chance of being in either one, just as we instinctively assign the same odds to a coin toss.

It is baffling how someone could think that probability is some sort of physical thing. Probability is just a mathematical interpretation, and the claims of this paper do not make any sense. And even if probabilistic aspects of observable events are attributable to quantum mechanics, that still would not say anything about the multiverse.