Nov 162024
 

For many years now, I’ve been receiving regular invitations from low-quality, predatory journals to contribute papers.

Needless to say, I didn’t.

But today, it reached a new low. I was offered, in exchange for the princely sum of $30, “authorship positions” in any one of a set of 19 papers.

Holy macaroni. Or whatever.

The esteemed journal in question that is inviting me to throw away any semblance of scientific ethics just to have my name appear… somewhere, calls itself the International Astronomy and Astrophysics Research Journal. Several paragraphs later in the e-mail I learn the…

List of Ready Paper

1. Advances in Dark Energy Research: Understanding the Mystery of the Accelerating Universe
2. Progress in Dark Matter Research: Bridging Observations and Theoretical Insights
3. A Review on Advances in Gravitational Waves Research
4. Recent Advances in the Cosmic Microwave Background Research: A Review
5. Galaxy Formation and Evolution: Progress in Recent Research
6. Computational Astrophysics Research: Review of the Recent Progress and Future Directions
7. Heavy-Ion Studies Research: Current Progress and Future Directions
8. Advances and Future Directions in Cosmic Ray Research: A Comprehensive Review
9. Gravitational Lensing: Review of Recent Progress and Future Directions
10. Advances in Black Hole Research and Future Directions: A Review
11. Exoplanet: Recent Developments and Future Directions: A Review
12. Recent Advances in Galaxy Formation Research and Future Developments
13. Galaxy Clusters: A comprehensive Review of Recent Developments
14. Recent Advances and Future Directions of Solar Physics Research
15. Recent Advances in Astrophysical Magnetism and the Interstellar Medium Research
16. A Review of Interstellar Black Holes: Navigating the Invisible
17. Recent Advances in Star Formation Theories: A Comprehensive Review
18. A Review of Recent Progress in Supermassive Black Holes and Galaxy Formation Research
19. Advances in Neutron Stars and Pulsars Research: Recent Progress and Future Directions

Yes, I’ve said it before, scientific publishing is in a crisis: flooded with low quality research, in need of qualified reviewers, stuck between two contradictory business models (subscription-based vs. open access publishing) and facing a deluge of for-profit, predatory publishers. But this represents a new low even within that dismal landscape.

 Posted by at 12:06 am
Sep 262024
 

Overleaf (sharelatex) is an amazing project, an open-source Web-based editor for LaTeX projects. The software can be used for free or on a subscription basis at overleaf.com, but the open source version is available as a “community edition”.

Not for the faint-hearted, mind you, as installation is not trivial. The easiest way is by means of a docker container, setup for which is provided by the Overleaf project.

In the last few days, I managed to do just that, installing Overleaf on my main Linux server. I even managed to configure Overleaf to properly compile Feynman diagrams automatically, as this screenshot from my practice “scratchpad” file demonstrates.

I like this project very much. In fact I am very impressed by its sophistication. I first opened an Overleaf account more than six years ago, when I invited someone to collaborate. I used Overleaf a few times over the years but, I admit, I forgot that it even exists until recently, when someone invited me to collaborate and I found, much to my surprise, that I already had a valid Overleaf account.

But this time around I went far beyond just using it. I decided to set up my own installation, for several reasons, including privacy, confidentiality, limitations and last but not least, avoiding reliance of a service provider who may or may not be still in business tomorrow or next year.

And now, I find myself ready to ditch the old software that I’ve been using for nearly 20 years, and switch to Overleaf altogether for my new LaTeX projects. It’s that good, really. I hope I will not come to regret my decision.

 Posted by at 1:10 am
Sep 072024
 

Starliner, made it safely to the ground, albeit without its crew.

Whatever unkind thoughts I have towards Boeing these days, this is good news.

 Posted by at 12:18 am
Aug 052024
 

It’s a civic holiday Monday that feels like a Saturday, reminding me of an old Soviet-era science-fiction novel, Monday begins on Saturday, by the Strugatsky brothers. It’s also a rather gloomy Monday morning, so it’s time for me to grumble about a few things.

For instance, how politics infuses everything these days. I signed up to follow a Facebook group dedicated to brutalist architecture, which for some inexplicable reason, I like. The comments section in one of the first posts I saw rapidly deteriorated into political bickering, as to whether or not it was appropriate to repurpose one of the Nazi-era indestructible flak towers in Hamburg as a luxury hotel. Because you know, politics is everything.

Speaking of which, I saw another post elsewhere about employees of a large US company who, after being told how successful the company was last year, were informed in the same breath that the company will cut their pension plan contributions. Needless to say, there followed comments about the evils of capitalism. Having experienced both capitalism and one of its alternatives, a socialist economy with central planning, all I can say is that capitalism works most of the time until it doesn’t; but when it doesn’t, victims are ever so eager to replace it with something that never works instead.

Then there was this post at an online news site claiming that it is practically impossible to run an ethical AI company. Well, what can I say? If you are telling me that allowing machine learning algorithms to learn from accumulated human knowledge is unethical, then sure, you are absolutely right. Then again, I suspect that what mainly drives such complaints is blatant ignorance of how machine learning works in the first place.

OK, well, never mind that, there’s good news. A fusion energy breakthrough: Neutron impact on tokamak components uncovered. Er… Say again? You are telling me that after 70+ years of research, we are beginning to understand why, or how, a heavy neutron flux rapidly destroys test equipment in the lab? Isn’t that like, say, greeting it as a “steam turbine breakthrough” when a prehistoric tribe manages to draw a spark from slamming together two rocks?

Oh well. On mornings like this, I feel I am beginning to comprehend the mood of the late, great Kurt Vonnegut who once told the CBC’s Anna Maria Tremonti to go jump in a lake.

 Posted by at 1:12 pm
Aug 022024
 

The title of this blog post is used as the byline or catch phrase of the Canadian Centre for Experimental Radio Astronomy, a group operating a 12.8 meter radio telescope, a repurposed former NATO satellite communication facility, located in Carp, just outside of Ottawa.

One of the things they organize is a summer camp for students. Today, I was invited to talk to a small group of students, and indeed I did so, talking (mostly) about my work on the Pioneer Anomaly. It seemed like an appropriate topic, considering that detection and resolution of the anomaly was heavily dependent on radio science, specifically Doppler radio navigation.

It was fun, and my talk, I am told, was well received. I was also offered an opportunity to briefly tour the facility itself. It was fascinating, even though it was insanely hot inside the dome under the August sun. (I definitely needed a shower when I got back home.) The only memorable fly in the proverbial ointment is that I arrived late, thanks to a stupid disabled truck that blocked the Queensway, as a result of which it took forty minutes to get from Vanier Parkway to Parkdale. Fortunately, my hosts were understanding.

 Posted by at 8:43 pm
Jun 072024
 

I had a very busy day today. Or make that yesterday, since it’s almost 3 AM already.

I wanted write something about D-day. Eighty years. It’s been eighty years since Americans, Canadians, Britons and others of the Greatest Generation landed on the beaches of Normandy, opening a much-awaited second front in the global struggle against fascist totalitarianism.

The result: An imperfect, yet enduring world order, Pax Americana, which brought historically unprecedented peace, prosperity, and security to the majority of humans living on this planet.

Perfect it was not. Totalitarianism never vanished. Even after Stalin’s death, the USSR and its empire prevailed for another 36 years. Some of the worst excesses of communism were yet to come. And there were wars, big wars: I thought I’d list a few but there were too many. Even so, this was a period of global peace, a rules-based system that endured, beyond expectations I should say: When I was growing up, no sane adult existed anywhere I think who expected the world to survive beyond the year 2000 without a major nuclear war, yet here we are in 2024, and there are still no nuclear wastelands.

But eventually, all good things come to an end. This world order is crumbling. Will we survive without a civilizational catastrophe? I don’t know. I worry. Ukraine, the Middle East, Taiwan… who knows what else. The retreat of democracy and the rise authoritarianism. The storm is brewing.

Anyhow, enough about D-day. There were some good news. Boeing’s Starliner, though limping a little, made it to the International Space Station. Those astronauts were brave souls. Considering recent news from Boeing, their newfangled attitude towards quality control and safety, I expected, feared rather, a disaster. I am relieved that it has not happened, but NASA should still dump that overpriced, unsafe contraption.

Meanwhile, Musk’s SpaceX had a major success: Starship completed a full test, involving successful launch and “landing” (onto the ocean for now) of both its first stage and Starship itself. The re-entry was not without challenges, but they made it. This is a big milestone, a very big one. The promise of Starship is basically the holy grail of space travel: Fully reusable, rapidly refurnished vehicles. The fiery reentry was perhaps a bit more dramatic than planned, but the spacecraft made it, and that means that they can learn from the issues and improve both the vehicle and its landing procedure.

And I was only marginally paying attention because I am still struggling with forced upgrades: CentOS 7, the Linux version that I’ve been using since 2016, is coming up EOL (end-of-life) which means I must upgrade. But I cannot upgrade to CentOS because Red Hat turned CentOS into a bleeding edge version of Linux with a short support cycle. Joy. Anyhow, today I managed to complete another milestone of my transition plan, so I may still be able to get everything done in time.

 Posted by at 3:06 am
May 062024
 

A couple of months ago, I came across a nice paper, by Verma and Silk (of Silk damping fame, as he’s known to cosmologists), showing what would happen if we had a chance to view the “shadow” of a supermassive black hole as it is microlensed by an intervening smaller black hole along the line-of-sight.

It occurred to me that I have the means to model this. At first I thought I’d write a short paper. But there really is nothing new that I can add to what Verma and Silk said in their paper, other than a nice animation produced by my ray tracing code.

So here it is. A brief animation of a small black hole passing in front of the famous “shadow”.

Things are not exactly to scale, of course, but for what it’s worth, this video corresponds roughly to a 10,000 solar mass black hole passing through, halfway between us and Sagittarius A*.

 Posted by at 11:59 pm
May 052024
 

I finally saw last year’s blockbuster, Oppenheimer. Let’s just say that my reaction to the film is not exactly in the mainstream.

That is, Best Picture my ass.

I am okay with Murphy’s Best Actor. Downey Jr. was especially good, earning his Best Supporting Actor in a role that I can only describe as unpleasant, playing the main villain of the Oppenheimer story, Lewis Strauss.

An actual photo of the real Oppenheimer

But the film?

For starters, there’s the jumbled timeline.  I am deeply familiar with the Manhattan project, and reasonably familiar with Oppenheimer’s life, including the story of the humiliating revocation of his security clearance in the 1950s. Even so, I was confused: I had a hard time keeping track of what I was seeing.

Then, there are some of the portrayals. Teller was unrecognizable. Where was the famous limp? And what’s with the accent? Sometimes, no accent at all, sometimes an accent that, whatever it was, didn’t sound even remotely like Teller’s. For some of the other, well-known physicists, it was same thing: I’m glad the closed caption sometimes showed the name of the person talking, otherwise, I swear I would not have known that one of them was Szilard, for instance. And Groves? His portrayal by Matt Damon was more like a caricature than the real general.

And then there are the gratuitous sex scenes. I hope I don’t come across as a prude by mentioning this, but… was it really necessary? I mean, yes, I get it, their penetrating questions about Oppenheimer’s private life were metaphorically undressing him, but was it really necessary to assume that the audience is so dumb, they won’t “get it” unless you put Oppenheimer, stark naked, fucking his girlfriend right there in the chair in the conference room while he is being interrogated? Seriously, this was so over the top, I could not believe my eyes. My reaction was that they were trying to out-Kubrick Kubrick, but without the talent of Kubrick (and I am decidedly not a Kubrick fan.)

Then how about the conversations? Some of them, I swear, sounded like a bad AI (no, not GPT-4 or Claude 3, more like GPT-2 or compact versions of Llama) trying to recreate conversations between scientists. I don’t want to set an impossible standard here. How about just meeting the standard, say… of a sitcom? The Big Bang Theory and Young Sheldon are both more respectful of the science (and the intellectual quality of discussions between scientists) than this film.

And some of the scenes were just grossly inauthentic. Never mind misrepresenting the then-perceived significance of the Oppenheimer-Snyder paper on gravitational collapse (yes, it is significant, but no, the term “black hole” was not even coined until a quarter century later), what was that with that childish celebration when the print edition arrived? By then, Oppenheimer and his colleagues would have known for months that the paper was accepted. Oppenheimer would have seen, and corrected, the galley proofs. The fact that print copies of the journal would appear on the appointed date would have been neither a surprise nor news to anyone involved.

What about the things that were omitted from the film? And no, I am not talking about technical details, not even the massive role facilities other than Los Alamos played in the development of the bomb. How about Oppenheimer’s 1960 visit to Hiroshima? It could have offered some profound moments, perhaps even allowing the film to conclude in a way much more fitting than the stupid “burn the atmosphere” CGI.

And speaking of CGI… what’s with the Trinity explosion itself? I read somewhere that it was not CGI. I could tell… it felt cheap. A bit like the explosion of the planet Alderaan in the original Star Wars movie, before the remaster.

The film had some redeeming segments, especially in the final half hour, but even those were overplayed, like that final (as far as I know, wholly fictitious) conversation between Oppenheimer and Einstein. Certainly not enough to salvage the movie for me. The best part were the end credits, as the music score was decent (not sure about Best Original Score quality, but it was enjoyable).

All in all, between the two acclaimed blockbusters from last year, in my view, Barbie won hands down.

Incidentally, I reminded myself that I had an equally negative view of another famous blockbuster from ten years ago, Interstellar: crappy story, crappy science, a psychedelic scene that wanted to be a bit Kubrick-like but couldn’t quite make it (and I absolutely hated what Kubrick has done with the closing scenes of 2001: A Space Odyssey). What I didn’t realize until this moment is that both Interstellar and Oppenheimer were directed by the same Christopher Nolan. Guess that makes it official: I am no fan of Christopher Nolan! On the other hand, I suppose I am a fan of his younger brother: I liked Westworld, and I am beyond impressed by what he did with Fallout.

 Posted by at 11:27 pm
Apr 302024
 

One of the reasons why I find the sitcom, The Big Bang Theory, as well as its spinoff, Young Sheldon, enjoyable, is the fact that they respect the science.

That is to say, the science that we see pop up in the series from time to time is, well, it may be fictitious but not bogus. Not gobbledygook.

Here’s the latest example. In the most recent Young Sheldon episode, we see Sheldon’s first paper, published in the fictitious journal, “International Physics Review”.

The journal may be fictitious, but the format is not: It’s the standard Physical Review layout, pretty much. Looks quite legit!

The title actually makes sense. The Calabi-Yau manifold is a popular mathematical tool, used to deal with, or “compactify” the unwanted excess dimensions of 10-dimensional supersymmetric string theory.

The abstract cannot be read in full, but the words that are visible are not nonsense. OK, as far as I know there is no “Vail-Walker metric compactification”, but the fragments of text that we can read actually make sense, sort of: which is to say, the words are not randomly strung together, they actually form expressions that you might encounter in entirely legitimate physics texts.

I mean, usual Hollywood would have something like this Midjourney creation on a sheet of paper or a blackboard:

Midjourney’s response to the prompt, “A gentlecat physicist in front of a blackboard discussing the Schwarzschild metric”.

I mean, Midjourney draws lovely physicist cats, but it certainly knows nothing about the Schwarzschild solution. The creators of The Big Bang Theory do: If Sheldon Cooper talks about the Schwarzschild solution, you can bet that in the background, on the blackboard you’d see something like \(ds^2=(1-2GM/r)dt^2-(1-2GM/r)^{-1}dr^2-r^2d\theta^2-r^2\sin^2\theta d\phi^2.\)

 Posted by at 11:43 pm
Apr 232024
 

Despite working with them extensively for the past 18 months or so, our “little robot” friends continue to blow me away with their capabilities.

Take this: the other day I asked Claude opus 3 to create an N-body simulation example from scratch, in HTML + JavaScript, complete with the ability to record videos.

Here’s the result, after some very minor tweaks of the code produced by Claude, code that pretty much worked “out of the box”.

The code is simple, reasonably clean and elegant, and it works. As to what I think of our little robot friends’ ability to take a brief, casual description of such an application and produce working code on demand… What can I say? There’s an expression that I’ve been overusing lately, but it still feels the most appropriate reaction: Welcome to the future.

 Posted by at 6:11 pm
Apr 202024
 

So here is the thing. When you announce to the world your latest breakthrough in quantum computing, you might want to make sure first that the results cannot be replicated using hardware that is nearly half a century old, from the heyday of 8-bit personal computers.

Granted, the paper announcing this result was presented at a joke conference, but the paper itself is no joke: It’s actually quite well-written and the results appear credible.

I admit I loved this result because not only does it provide an example supporting my skepticism of sensationalist quantum computing claims, it also involves the computer that played a significant role in my early career, and which also happens to be the first computer that I proudly owned.

Of course the real point is that sensationalist coverage aside, apart from highly specialized, niche applications in which quantum computers basically play the role of specialized analog computers, the “quantum revolution” will not happen without scalable quantum computing, and scalable quantum computing will not happen without beating the threshold theorem. I am one of the skeptics: I strongly suspect that the threshold theorem will be shown to be a “no go” theorem. It is, of course, entirely possible that I am wrong about this, but in my mind, quantum computing is in the same league as fusion power: a technology that forever remains “just around the corner”.

 Posted by at 7:52 pm
Jan 282024
 

I first bought a hybrid (a Honda Civic) in 2004. I loved that car; it served us faithfully for 10 years. Our more recent Hondas were not hybrids, but the reasons were eminently practical: hybrids were in short supply, conventional gasoline cars were cheaper, and we use the car very little in any case, so…

Having said that, I certainly contemplated the idea of buying an all electric vehicle, but every time I think it through, I decide against it. Today, I saw a map that perfectly illustrates my lack of enthusiasm. Here it is:

This map shows the locations of supercharger stations where you’d have to stop for a 20-30 minute recharge, in order to complete a cross-country trip across the United States in a Tesla automobile.

In contrast, here’s a map of an actual trip I took in my Civic Hybrid back in 2005, along with the approximate locations where I stopped for gas (reconstructed from old receipts):

What can I say? I think EVs are great when you live in the suburbs and use your car for shopping and commuting to work. If I lived, say, in Kanata and commuted daily to work at, say, Place du Portage in Gatineau, purchasing an EV would make an awful lot of sense. But that’s not where we live or how we commute. We live on Ottawa Lowertown, which is to say almost downtown, we work at home, we use the car only occasionally, but as this example demonstrates, sometimes for lengthy road trips. EVs are not great for lengthy road trips. I am used to the idea of driving to Montreal Airport and back without worrying about stopping for gas. Or driving to Toronto non-stop.

And then, of course, there are the dreaded Canadian winters. It’s one thing to use waste heat from a gasoline engine to heat the interior of a car. It’s another thing to waste electric power stored in a battery for this, converting electricity inefficiently into heat, at the expense of range already reduced by the effect of cold weather on the batteries. And while heat pumps can help, there are no miracles when the outside air temperature is closer to -40 than -30 Centigrade, which is a not altogether uncommon occurrence (though it is certainly becoming less common) in these parts of Canada.

And then there’s the question of where the electric energy comes from. Renewables are okay, nuclear would be great. But too much of the electricity, even here in nuclear-rich Ontario, comes from natural gas fired plants. That’s not so great.

So for now, it’s either gasoline-powered or hybrid vehicles for us. EVs may be in our future, but I am not yet too keen on them, to be honest.

 Posted by at 3:05 pm
Jan 242024
 

Someone sent me a link to a YouTube podcast, a segment from an interview with a physicist.

I didn’t like the interview. It was about string theory. My dislike is best illustrated by a point that was made by the speaker. He matter-of-factly noted that, well, math is weird, the sum of \(1 + 2 + 3 + …,\) ad infinitum, is \(-\tfrac{1}{12}.\)

This flawlessly illustrates what bothers me both about the state of theoretical physics and about the way it is presented to general audiences.

No, the sum of all positive integers is not \(-\tfrac{1}{12}.\) Not by a longshot. It is divergent. If you insist, you might say that it is infinite. Certainly not a negative rational number.

But where does this nonsense come from?

Well, there’s the famous Riemann zeta-function. For values of \(s>1,\) it is indeed defined as

$$\zeta(s)=\sum_{n=1}^\infty \frac{1}{n^s}.\tag{1}$$

It is a very interesting function, at the heart of some unresolved problems in mathematics.

But the case of \(s=-1\) (which is when the right-hand side of the equation used to define \(\zeta(s)\) corresponds to the sum of all positive integers) is not an unresolved problem. As it is often presented, it is little more than a dirty trick befitting a cheap stage magician, not a scientist.

That is to say, the above definition of \(\zeta(s),\) as I said, is valid only for \(s>1.\) However, the zeta-function has what is called its analytic continuation, which makes it possible to extend the definition for other values of \(s,\) including \(s=-1.\) This can be accomplished utilizing Riemann’s functional equation, \(\zeta(s)=2^s\pi^{s-1}\sin(\tfrac{1}{2}\pi s)\Gamma(1-s)\zeta(1-s).\) But the right-hand side of (1) in this case does not apply! That sum is valid only when it is convergent, which is to say (again), \(s>1.\)

A view of the Riemann zeta-function, from Wikipedia.

So no, the fact that \(\zeta(-1)=-\tfrac{1}{12}\) does not mean that the sum of all integers is \(-\tfrac{1}{12}.\) To suggest otherwise only to dazzle the audience is — looking for a polite term here that nonetheless accurately expresses my disapproval — well, it’s dishonest.

And perhaps unintentionally, it also shows the gap between robust physics and the kind of mathematical games like string theory that pretend to be physics, even though much of it is about mathematical artifacts in 10 dimensions, with at best a very tenuous connection to observable reality.

 Posted by at 10:48 pm
Jan 192024
 

Japan’s SLIM (Smart Lander for Investigating Moon) made it to the lunar surface. Well… sort of. It accomplished its main goal of a targeted soft landing.

Unfortunately, its solar panels are non-operational. It’s unclear for now why (one speculation I read is that the lander may have tipped over after landing). Its batteries can power it only for a few hours. They’re hoping that perhaps later in the lunar day, or in a next lunar cycle, the lander will get sunlight from the right direction to be able to recharge its batteries after all.

Even so, Japan is now officially the fifth country to have landed a spacecraft on the Moon that remained (at least partially) operational on the lunar surface.

 Posted by at 2:01 pm
Jan 182024
 

I gave a brief invited talk today via Zoom, participating in a workshop on cosmological models, organized by Complutense University of Madrid, Spain.

The subject of my talk was John Moffat’s theory of gravitation, MOG/STVG, to which I made significant contributions myself over the past 18 years, in an on-going collaboration with John. Judging by the questions that followed my short presentation, I think it was reasonably well received.

The workshop was streamed live on YouTube, and the video is archived.

 

 Posted by at 9:25 pm
Dec 062023
 

A few days ago, I came across an article that described a remarkable paper, published in the USSR more than 50 years ago, with predictions on climate change.

Predictions that proved remarkably prescient.

I first read about Mikhail Budyko’s article in a recent review, published on EOS three years ago. What caught my attention, in particular, was Fig. 1 of that article, reproduced below, that shows just how spot on Budyko’s predictions happen to be.

Budyko’s 1972 predictions (solid gray lines) of a) surface temperature and b) changes in Arctic sea ice, compared to observational data from NASA Goddard and IPCC predictions.

Naturally, I wanted to see the original reference, which proved harder than I expected. While it was cited many times, the paper was almost impossible to find. Although I did locate it in an online Russian library, it was only an index entry, with the (unscanned) copy available only for reading in person.

But then… Fortunate favors the… foolish? Persistent? I stumbled upon a 2020 Russian-language publication containing full reprints of several papers by Mikhail Budyko, including the paper in question.

I took it upon myself then to translate the paper in its entirety, with help from one of our AI friends. (AI can do a remarkable job translating technically challenging content, much better than dedicated translation software, albeit some supervision is required.)

Yes, Budyko indeed accurately predicted human-induced climate change. His concerns about rapid changes, “tipping points” are also well-justified. Notably, his work was written before climate change became political football. It’s the work of an excellent climate scientist, not a political hack.

 Posted by at 11:57 pm
Dec 052023
 

Now that Roy Kerr’s paper on black holes and singularities is on arXiv, I am sure I’ll be asked about it again, just as I have been asked about it already on Quora.

Roy Kerr, of course, is one of the living legends of relativity theory. His axisymmetric solution, published in the year of my birth, was the first new solution in nearly half a century after Karl Schwarzschild published his famous solution for a spherically symmetric, static, vacuum spacetime. I hesitate to be critical of this manuscript since chances are that Kerr is right and I am wrong.

Kerr now argues that the singularity theorems are nonsense, and that his axisymmetric solution actually hides some nonsingular configuration of matter therein.

At a first glance, the paper seems well written and robust. Still… when I dug into it, there are a few things that caught my attention, and not in a right way. First, the paper takes argument with “singularity believers” using language that almost sounds like pseudoscience. Second, it has some weird factual errors. E.g., it asserts that black holes “as large as 100 billion solar masses have been observed by the James Webb Telescope” (not even close). Or, it describes the famous Oppenheimer-Snyder paper of 1939 as having “used linear, nineteenth century ideas on how matter behaves under extreme pressures” (actually, Oppenheimer and Snyder discuss the collapse of a “dust” solution with negligible pressure using the tools of general relativity with rigor). Kerr further criticizes the Oppenheimer-Snyder paper as attempting “to ‘prove’ that the ensuing metric is still singular”, even though that paper says nothing about the metric’s singularity, only that the collapsing star will eventually reach its “gravitational radius” (i.e., the Schwarzschild radius). Nonetheless, later Kerr doubles down by writing that “Oppenheimer and Snyder proved that the metric collapses to a point,” whereas the closest the actual Oppenheimer-Snyder paper comes to this is describing collapsing stars as stars “which cannot end in a stable stationary state”.

Never mind, let’s ignore these issues as they may not be relevant to Kerr’s argument after all. His main argument is basically that Penrose and Hawking deduced the necessary presence of singularities from the existence of light rays of finite affine length; i.e., light rays that, in some sense, terminate (presumably at the singularity). Kerr says that no, the ring singularity inside a Kerr black hole, for instance, may just be an idealized substitute for a rotating neutron star.

Now Kerr has an interesting point here. Take the Schwarzschild metric. It is a vacuum solution of general relativity, but it also accurately describes the gravitational field outside any static, spherically symmetric distribution of matter in the vacuum. So a Schwarzschild solution does not imply an event horizon or a singularity: they can be replaced by an extended, gravitating body that has no singularities whatsoever so long as the radius of the body is greater than the Schwarzschild radius associated with its mass. The gravitational field of the Earth is also well described by Schwarzschild outside the Earth. So in my reading, the crucial question Kerr raises is this: Is it possible that once we introduce matter inside the event horizon of a Kerr black hole, perhaps that can eliminate the interior Cauchy horizon or, at the very least, the ring singularity that it hides?

I don’t think that is the case, and here is why. Between the two horizons of a Kerr black hole, the “radial” coordinate is now the timelike coordinate, with the future pointing “inward”, i.e., towards the Cauchy horizon. That means that particles of matter do not have trajectories that would allow them to avoid the Cauchy horizon; no matter what path they follow, they will reach that horizon in finite proper time.

Inside the Cauchy horizon, anything goes, since closed timelike curves exist. So presumably, it might even be possible for particles of matter to travel back and forth between the past and the future, never hitting the ring singularity. But that’s not what Kerr is suggesting in his paper; he’s not talking about acausal worldlines inside the Cauchy horizon, but some “nonsingular interior star”. I don’t see how to make sense of that suggestion, because I don’t see how a stationary configuration of matter could exist inside the inner horizon. Wobbling back-and-forth between yesterday and tomorrow in a closed timelike loop is not a stationary configuration!

For these reasons, even as I am painfully aware that I am arguing with a Roy Kerr so there’s a darn good chance that he’s right and I’m spouting nonsense, I must say that I remain unconvinced by his paper. The language he uses (e.g., describing the business of singularities as “dogma”) is not helping either. Also, his description of the interior of the rotating black hole sounds a bit off; to use his own words, “nineteenth century” reasoning, much more so than the Oppenheimer-Snyder paper that he criticizes.

 Posted by at 7:31 pm
Dec 022023
 

I just came across a quote attributed to Einstein: “If I had foreseen Hiroshima and Nagasaki, I would have torn up my formula in 1905.

The problem with this quote is that it is utter nonsense, and not something Einstein likely would have said, ever.

An image of Einstein that is just as real as some of the quotes attributed to him. Courtesy of Midjourney.

The “formula” of mass-energy equivalence simply states that an object’s resistance to motion (its inertia) is proportional to its energy-content. That is all. Yes, I know that in the popular imagination, \(E=mc^2\) is frequently associated with the nuclear age. But that’s nonsense. \(E=mc^2\) is not about “converting” anything into anything. Mass-energy is mass-energy, and it is conserved. Whether it is in the form of the nuclear binding energy of a uranium atom (or for that matter, the chemical binding energy of carbon atoms in a fireplace log) or in the form of the kinetic energy of photons released by a nuclear or chemical reaction has absolutely nothing to do with \(E=mc^2\): the formula does not explain nuclear fission any more than it explains the chemical reactions that govern the burning of wood.

But then, what about this quote, which appears in a number of reliable places, including Wikiquotes?

It is attributed to a book published by a William Hermanns, who supposedly interviewed Einstein on a number of occasions between the late 1920s and Einstein’s death in 1955.

The person appears real. I found, in Google’s archive, the May 2, 1955 issue of Life, which includes a personal recollection of one of Life’s own editors, William Miller, of his very last visit to Einstein, when he actually met William Hermanns.

Hermanns’s book, Einstein and the Poet: In Search of the Cosmic Man, is also real: In fact, it even has a Kindle edition.

But… how much of it is true?

Considering that Hermanns has an exceptional biography (which one can read on a Web site dedicated to his life) it is more than a bit odd that the only references to his name in Wikipedia are Einstein-related. Yet his name does not appear in notable Einstein biographies, including Abraham Pais’s definitive scientific biography, or Walter Isaacson’s exceptionally good Einstein bio.

When I read the few pages of Hermanns’s book that are available as a Kindle preview, I grow even more suspicious. For instance, according to Hermanns, already in 1927 Einstein was “marked by Nazis as ‘Enemy number One of the Nation,’ and the object of at least seven plots to take his life.” News to me.

But then, Hermanns goes on to quote Einstein who supposedly said, “When I was about five, my father gave me a compass as a toy. I wanted to find out why the needle never deviated […] When I asked my uncle, an engineer, he immediately proceeded to teach me some fundamentals of algebra, with this advice: ‘What you don’t know, call x, then hunt til you find what it is.’ From that time on, I have called everything I didn’t know x, especially magnetism.

As I asked ChatGPT just moments ago, can you imagine Einstein saying these words, in 1927, to a stranger who just visited him?

Long story short, I don’t know what to think. Based on what I have read, I do not believe Hermanns’s accounts of his conversations with Einstein are credible. At the very least, they must be severely distorted versions of Einstein’s words, probably deeply colored, warped by Hermanns’s imagination. For what it’s worth, ChatGPT concurs: “The lack of independent verification and recognition in authoritative sources casts doubt on the accuracy and credibility of his accounts. Your reservations about accepting Hermanns’ narratives as factual are well-founded.”

 Posted by at 11:32 pm
Nov 302023
 

I made some mistakes in the past. I never made a half-a-billion dollar mistake.

Neither did Chris Lewicki, but he came awfully close.

I just read this delightful account of how Lewicki almost fried the innards of the Spirit rover, destined for Mars, during an engineering test that took place just weeks before the rover was launched.

I can only imagine the sinking feeling in his stomach he must have felt when he thought that the rover was ruined. My mistakes never came close in value, but the sensation is uncomfortably familiar.

Fortunately, in his case, the disaster never actually materialized. In simple terms, yes, he plugged a cord into the wrong outlet, but fortunately, the other end of the cord was not plugged in.

To this day, Lewicki must feel like one of the luckiest persons on the planet.

The illustration is from his blog post, but its appearance suggests that it might have been produced by DALL-E. Or maybe Midjourney or Stable Diffusion? The style looks very reminiscent of AI-produced cartoon images.

 Posted by at 6:17 pm