For years now I have written about the quantum physics of black holes, and each and every time I have pushed a single idea: that if black holes behave as (almost perfect) black bodies, then they should be described by the same laws as black bodies are. And that means that besides the obvious processes …
The picture above is of von Neumann, Feynman, and Ulam. More Ulam. See also the nature of intuition and intuition and the two brains. Adventures of a Mathematician: (p.147-148) … the main ability to have was a visual, and also an almost tactile, way to imagine the physical situations, rather than a merely logical picture …
Ashton Carter won’t be the first physicist to lead the Department of Defense. Harold Brown was President of Caltech and Secretary of Defense under Carter. Caltech Oral History interview: BROWN: You asked me first for a brief review of my career before coming to Caltech. I grew up in New York [City] and went to Columbia University for …
The manifestation of dark energy on cosmological scales is well known: gravitational repulsion which leads to the accelerating expansion of the universe. Perhaps surprisingly, there are potentially observable effects on galactic length scales as well. The Dark Force: Astrophysical Repulsion from Dark Energy (http://arxiv.org/abs/1501.05952) Chiu Man Ho, Stephen D. H. Hsu Dark energy (i.e., a cosmological …
The paper below will appear in Int.J.Mod.Phys.A. We went through a strange series of referees during the last year, with reactions ranging from this result is correct but trivial to this result is highly nontrivial but possibly correct to, finally, this is a nice result and should be published. I would like to lock the first …
New paper! We show that quantum effects (in particular, the horizon temperature originally discovered by Gibbons and Hawking) modify the geometry of de Sitter spacetime. Instability of Quantum de Sitter Spacetime (http://arxiv.org/abs/1501.00708) Chiu Man Ho, Stephen D. H. Hsu Quantized fields (e.g., the graviton itself) in de Sitter (dS) spacetime lead to particle production: specifically, …
“It’s been only half jokingly said that today a third of GDP is attributable to quantum mechanics,” — former Lockheed CEO Norm Augustine. I’ve heard the one third or 30% of GDP figure from time to time, but have never seen a detailed analysis. A list of modern technologies that arose from quantum mechanics …
The full text of The Feynman Lectures is now available online. These lectures were originally delivered to satisfy the physics requirement for first and second year students at Caltech. Legend has it that as the lectures went on, fewer and fewer undergraduates were seen in attendance, with their places taken by graduate students and even members …
Secretary of Defense nominee Ashton B. Carter on his education and early career in theoretical physics. His Wikipedia entry says he did postdocs at Rockefeller University and MIT. … when I rather unexpectedly was accepted into a good college, Yale, I was determined to make the most of it. I disdained the “preppies” and other privileged students who seemed …
This is funny, and does capture the tendency of physicists (not just old ones) to wander into other fields. But the cartoon avoids the hard question (perhaps best addressed by historians of science) as to the actual value brought to other fields by physicists. See, for example, Physicists can do stuff, Prometheus in the basement, …
Here’s what you missed, in case you have stumbled into this series midway. As you are wont to do, of course. Part 1 had me reminiscing about how I got interested in the quantum measurement problem, even though my Ph.D. was in theoretical nuclear physics, not “foundational” stuff, and introduced the incomparable Hans Bethe, who …
This is the last installment of the “Nifty Papers” series. Here are the links to Part1, Part2, and Part 3. For those outside the computational physics community, the following words don’t mean anything: “The Sign Problem“ For those others that have encountered the problem, these words elicit terror. They stand for sleepless nights. They spell despair. They make grown men …
This is the third part of the “Nifty Papers” series. Link to Part 1. Link to Part 2. In 1999, I was in the middle of writing about quantum information theory with my colleague Nicolas Cerf. We had discovered that quantum conditional entropy can be negative, discussed this finding with respect to the problem of quantum measurement, separability, Bell inequalities, as well …
This is Part 2 of the “Nifty papers” series, talking about papers of mine that I think are cool, but that have been essentially ignored by the community. Part 1 is here. This is the story of my third paper, still as a graduate student (in my third year) at Stony Brook University, on Long …
I suppose this happens even to the best of us: you write a paper that you think is really cool and has an important insight in it, but nobody ever reads it. Or if they read it, they don’t cite it. I was influenced here by the blog post by Claus Wilke, who argues that …
A group of physicists have discovered that they can make objects move against the direction of waves by using a tractor beam on water, which generates waves. This has important real-world applications, including confining oil spills. The physicists do not yet know mathematical theories explaining how it works. Dr. Horst Punzmann said ” . . …
Let me briefly recap parts 1-3 for those of you who like to jump into the middle of a series, convinced that they’ll get the hang of it anyway. You might, but a recap is nice anyway. Remember these posts use MathJax to render equations. Your browser can handle this, so if you see a bunch …
I have a new candidate for coolest research institute architecture. HKUST’s Institute for Advanced Study is housed in an amazing building with a view of Clearwater Bay in HK. The members of the institute will be mostly theoretical physicists and mathematicians :-) Stiff competition from Benasque’s Center and the Perimeter Institute, however. Also Caltech’s IQIM! …
In the previous two parts, I told you how I became interested in the quantum measurement problem (Part I), and provided a bit of historical background (Part 2). Now we’ll get to the heart of the matter. Note that I’m using MathJax to display equations in this blog. If your browser shows a bunch of dollar …
I came across a PDF version of this book online. It contains a number of fine essays, including the ones excerpted from below. A recurring question concerning Godel’s incompleteness results is whether they impact “interesting” mathematical questions. CHAPTER 21 The Godel Phenomenon in Mathematics: A Modern View: … Hilbert believed that all mathematical truths are …
For this series of posts, I’m going to take you on a ride through the bewildering jungle that is quantum measurement. I’ve no idea how many parts will be enough, but I’m fairly sure there will be more than one. After all, the quantum mechanics of measurement has been that subject’s “mystery of mysteries” for …
If the title of this blog post made you click on it, I owe you an apology. All others, that is, those who got here via perfectly legitimate reasons, such as checking this blog with bated breath every morning–only to be disappointed yet again … bear with me. Here I’ll tell you why I’m writing …