I did not have ambitions 2017. It should have been a year of taking stock - and it was, in a good way.
- I time-travelled and re-lived some history of software engineering, and finally learned basics of computer science. This was philosophical delight, but also useful and necessary: I was able to boost the performance of my simulations (above a level of what was, maybe, embarrassingly slow).
- I tinkered a lot with numerical simulations of our heat pump system. Main thing I learned: The more modern the building, the more you'd need to simulate humans' behavior, rather than physics or control logic.
- Reverse engineering and troubleshooting is what finally connects all the fields of science and engineering I love: Troubleshooting, ferreting out hidden causes and effects in hydraulics feel the same as sniffing and debugging software and networking protocols.
- Theoretical physics reading: I returned to classical thermodynamics and statistical mechanics; I find it fascinating and beautiful in its own right, even if only at the pre-1960s level. I took stock of my writing on heat transport - and I am happy I can actually really use physics on a daily basis, in down-to-earth engineering projects.
- I was thinking about automation, standardization, and big social media platforms. I struggled with this blog post about the future of small business for a long time, but optimism won. I might frame this even more positively today: There is a place for artisanal service delivery despite or because of Everything Being Offered As A Service by Omniscient Data Krakens.
- My blog turned 5 in spring, and I allowed myself to return to a more philosophical blogging style (briefly). Otherwise, I finally and subconsciously made the elkement.blog my main resources of technical content - or at least content related to my professional domain, and content edited for clarity and entertainment. Whereas on elkement.subversiv.at I let my stream of consciousness flow. It seems that the pattern that finally emerges is: elkement.blog = elkement's tech / science magazine and platform for personal research news, with an ever growing focus on fields I have training in and daily practical exposure to. elkement.subversiv.at gravitates against the same focus, but I allow myself to focus on my personal perspective only. So here you find 'what I am doing with [insert: heat pumps, security,...]', over there you find the useful content as such.
- Tomato harvest was great. I tried to grow late varieties - like Ox Heart - directly outside, and it worked.
- Dinosaur Kale tastes good. And it is able to recover from a at attack of a bug that targets kale (and radishes' seed capsules). Don't try to keep seeds of radishes in the land of canola.
This website is an old-school non-interactive site. My blog technically isn't, but looks like one now, for the lack of visible comments. However, messages have reached over covert 1:1 channels, so I do now that there is a small but sincerely interested group of readers. I thank you all for reading my stuff!
I will try to explore my relationship with IT / software / computers / computer science / software engineering or whatever the best term is to describe it. I am in a mode of looking back with content, and making small changes, learning a bit more.
As often, thinking in 'opposites' comes most natural to me:
Self-study versus formal education. The IT and software industry is young and - I believe - had originally been populated by people without a formal training in computer science as this did not yet exist as an academic discipline. The community was open to outsiders with no formal training or unrelated experience. As a former colleague with a psychology background put it: In the old times, anybody who knew how to hold a computer mouse correctly, was suddenly considered an expert.
I absorbed the hacker ethics of demonstrating your skills rather than showing off papers, and I am grateful about the surprisingly easy start I had in the late 1990s. I just put up a sign in a sense, saying Will Do Computers, and people put trust in me.
I am not 'against' formal education though. Today I enjoy catching up on computer science basics by reading classics like Structure and Interpretation of Computer Programs.
Breaking versus building things. I have been accountable for 'systems' for a long time, and I have built stuff that lasted for longer than I expected. Sometimes I feel like a COBOL programmer in the year of 2000.
But I believe what interested me most is always to find out how stuff works - which also involves breaking things. Debugging. Reverse Engineering. Troubleshooting. All this had always been useful when building things, especially when building on top of or interfacing with existing things - often semi-abandoned blackboxes. This reverse engineering mentality is what provided the connection between physics and IT for me in the first place.
It was neither the mathematical underpinnings of physics and computer science, or my alleged training in programming - I had one class Programming for physicists, using FORTRAN. It was the way an experimental physicist watches and debugs a system 'of nature', like: the growth of thin films in a vacuum chamber, from a plasma cloud generated by evaporating a ceramic target bombarded with laser pulses. Which parameter to change to find out what is the root cause or what triggers a system to change its state? How to minimize the steps to trace out the parameter space most efficiently?
Good-enough approach versus perfectionism. 80/20 or maybe 99/1. You never know or need to know anything. I remember the first time I troubleshooted a client's computer problem. I solved it. Despite knowing any details of what was going on. I am sort of embarrassed by my ignorance and proud at the same time when I look back.
In moment like this I felt the contrast between the hands-on / good-enough approach and the perfectionism I applied in my pervious (academic) life. I remember the endless cycles of refinement of academic papers. Prefixing a sentence with Tentatively, we assume,... just to be sure and not too pretentious though I was working in a narrow niche as a specialist.
But then - as a computer consultant - I simply focused on solving a client's problem in a pragmatic way. I had to think on my feet, and find the most efficient way to rule out potential root causes - using whatever approach worked best: Digging deep into a system, clever googling, or asking a colleague in the community (The latter is only an option if you are able to give back someday).
Top-down, bottom-up, or starting somewhere in the middle. I was not a typical computer nerd as a student. I had no computer in high school except a programmable calculator - where you could see one line of a BASIC program at a time. I remember I had fun with implementating of the Simplex algorithm on that device.
However, I was rather a user of systems, until I inherited (parts of) an experimental setup for measuring electrical properties of samples cooled down by liquid nitrogen and helium. I had to append the existing patchwork of software by learning Turbo Pascal on the job.
Later, I moved to the top level of the ladder of abstraction by using *shock, horror* Visual Basic for Applications, ASP, and VBScript. In am only moving down to lower levels now, finally learning C++, getting closer to assembler and thus touching the interface between hardware and software. Which is perhaps where a one should be, as a physicist.
Green-field or renovation (refactoring). I hardly ever had the chance to or wanted to develop something really from scratch. Constraints and tough limiting requirements come with an allure of their own. This applies to anything - from software to building and construction.
So I enjoy systems' archaeology, including things I have originally created myself, but not touched in a while. Again the love for debugging complements the desire to build something.
From a professionals' point of view, this is a great and useful urge to have: Usually not many people enjoy fiddling with the old stuff, painstakingly researching and migrating it. It's the opposite of having a chance to implement the last shiny tool you learned about in school or in your inhouse presentation (if you work for a software vendor).
In awe of the philosophy of fundamentals versus mundane implementation. I blogged about it recently: Joel Spolsky recommended, tongue-in-cheek, to mention that Structure and Interpretation of Computer Programs brought you to tears - when applying for a job as a software developer.
But indeed: I have hardly attended a class or read a textbook that was at the same time so profoundly and philosophically compelling but also so useful for any programming job I was involved in right now.
Perhaps half of older internet writing reflects my craving for theses philosophical depths versus the hard truth of pragmatism that is required in a real job. At the university I had been offered to work on a project for optimizing something about fluid dynamics related to the manufacturing of plastic window frames. The Horror, after I had read Gödel, Escher, Bach and wanted to decode the universe and solve the most critical problems of humanity via science and technology.
I smile at that now, with hindsight. I found, in a very unspectacular way, that you get passionate about what you are good at and what you know in depth, not the other way round. I was able to possibly reconnect with some of my loftier aspirations, like I could say I Work In Renewable Energy. However, truth is that I simply enjoy the engineering and debugging challenge, and every mundane piece of code refverberates fundamental truths as the ones described in Gödel, Escher, Bach or Structure and Interpretation.
I have been blogging 'seriously' about physics since 2012. My motivation has been a blend of jotting down notes on interesting things I've just found, conveying my decades-old fascination with some phenomena, trying my hands at popular science writing, and reporting on my own research.
Today I am asking myself - did I learn anything from that on a meta level? To read myself, I am re-arranging the list of my physics posts and sort them by topic and sub-topic. The list says it all, I think.
I wanted to write about quantum mechanics, but it seems I was always most intrigued by classical mechanics, statistical mechanics, and thermodynamics. The latter has become my true home in physics - which has come as a surprise to myself. Yes, thermodynamics is my specialization, but years ago I rather figured that this is my job, and I rather want to follow the latest news on quantum information and particle theory in my spare time. It turned out that I am more interested in history of physics and in the evolution of concepts that are now 'well known'.
My recurring meta-topic is that classical mechanics / thermo can be as interesting, 'geeky' if you wish, mathematically 'weird', and surprising as fields that seem to be more popular.
This list may remain a static snapshot. I am editing the chronological list of my physics posts here on the blog. This list might lseem to lack some of my more applied / engineering postings, re our heat pump system and data. These are here.
Thermodynamics and Statistical Mechanics
Concepts and foundations
Random Thoughts on Temperature and Intuition in Thermodynamics
Time evolution of systems in phase space: On the Relation of Jurassic Park and Alien Jelly Flowing through Hyperspace.
Phase-space in depth: Hyper-Jelly – Again. Why We Need Hyperspace – Even in Politics.
Carnot’s efficiency, irreversibility, proof by contradiction, paradoxes: Re-Visiting Carnot’s Theorem.
Mathematics used in statistical mechanics: Spheres in a Space with Trillions of Dimensions.
Heat pump basics
Brief explanation, absolute temperature:
Why Do Heat Pumps Pump Energy so Easily?
Coefficient of Performance of a heat pump: An Efficiency Greater Than 1?
Cross-check of numbers for a large heat pump system: Pumped Heat from the Tunnel
COP versus Performance Factor: How to Evaluate a Heat Pump’s Performance?
Energy accounting, economics: Heat Pump System Data: Three Seasons 2012 – 2015.
Heat conduction, diffusivity, latent heat:
Storage Challenge: High Score!
Heat conduction, heat equation: Temperature Waves and Geothermal Energy.
Heat diffusion length: Rowboats, Laser Pulses, and Heat Energy (Boring Title: Dimensional Analysis).
Simple version, daily energy balances:
More Ice? Exploring Spacetime of Climate and Weather.
Heat transport, energy balances. Simulations versus simple energy accounting: Ice Storage Hierarchy of Needs.
Detailed version: Heat exchangers, heat equation, 1-minute time slots: Simulating Peak Ice.
Thermodynamics and energy basics, dimensional analysis
kW and kWh.
No, You Cannot ‘Power Your Home’ by One Hour of Cycling Daily.
Phase transitions, ideal gas law (pressure sensor) Mr. Bubble Was Confused. A Cliffhanger.
kWp, power, energy, energy flow: On Photovoltaic Generators and Scattering Cross Sections.
History and inventions
Einstein’s Refrigerator and other inventions:
Einstein and His Patents
Centennial light bulb, sustainability: 111 Years: A Shining Example of Sustainable Product Development?
Checking 19th century papers: Peter von Rittinger’s Steam Pump (AKA: The First Heat Pump).
Phase transitions of water, Mpemba effect: A Sublime Transition.
By an Austrian start-up – pressure gradient created by centrifugal forces: And Now for Something Completely Different: Rotation Heat Pump!
(I realize that some of my articles in the 'engineering' category would also qualify for this sub-category History. For example: I wrote a - less detailed - post on Rittinger's steam pump before. But part of the fun with these list is that you have to take those hard decisions of tagging ...)
Classical Mechanics and Fluid Dynamics
Equations of motion and Lagrangian formalism
Principle of Least Action.
Sniffing the Path (On the Fascination of Classical Mechanics)
Equation of motion, intuition in physics: Are We All Newtonians?
Motion of a falling slinky spring: The Falling Slinky and Einstein’s Elevator.
Principle of Least Action, again – extended version: Space Balls, Baywatch and the Geekiness of Classical Mechanics.
From Newton’s Law to Navier-Stokes Equations: Non-Linear Art. (Should Actually Be: Random Thoughts on Fluid Dynamics).
Estimates related to the physics of scything:
Grim Reaper Does a Back-of-the-Envelope Calculation.
Back-of-the-envelope cross-checks, hydro power: All Kinds of Turbines.
Torque, forces, precession, nutation.
The Spinning Gyroscope and Intuition in Physics.
Another way to explain how the gyroscope works: Intuition and the Magic of the Gyroscope
Coriolis force (1): The Twisted Garden Hose and the Myth of the Toilet Flush:
Coriolis force (2). Lest We Forget the Pioneer: Ottokar Tumlirz and His Early Demo of the Coriolis Effect.
Physics and geometry
My first (later corrected) proposal of a solution:
Physics / Math Puzzle: Where Is the Center of Mass?
Correcting my earlier proposal: Revisiting the Enigma of the Intersecting Lines and That Pesky Triangle.
Newton’s geometrical proof of Kepler’s laws: Mastering Geometry is a Lost Art.
Quantum Mechanics and Quantum Field Theory
Interpretations of quantum mechanics:
Is It Determinism if We Can Calculate Probabilities Exactly?
Quantum Mechanics versus QFT: Quantum Field Theory or: It’s More Than a Marble Turned into a Wiggly Line.
Started a series: And Now for Something Completely Different: Quantum Fields!
Summary on QM: May the Force Field Be with You: Primer on Quantum Mechanics and Why We Need Quantum Field Theory
Quantization – starting from statistical mechanics: On the Relation of Jurassic Park and Alien Jelly Flowing through Hyperspace.
Path integrals and symmetries: Learning Physics, Metaphors, and Quantum Fields.
Book review: Student Friendly Quantum Field Theory.
Electromagnetism and special relativity
Unification of Two Phenomena Well Known.
Charged particles lose energy when accelerating: Why Fat Particles Radiate Less.
An alternative way of understanding SR: How to Introduce Special Relativity (Historical Detour).
List of resources: Learning General Relativity.
Using physics-like methods in economics and sociology
Networking theory, instabilities:
Theory and Practice of Trying to Combine Physics with Anything
E-Mails and communications: Using Social Media in Bursts. Is. Just. Normal.
‘Philosophical’: Learning physics, culture
On trying to explain physics without math:
Real Physicists Do Not Read Popular Science Books
Re The Trouble with Physics by Lee Smoli:. I neither Met Newton nor Einstein
On learning physics. Stupid Questions and So-Called Intuition.
Re Margaret Wertheim’s Physics on the Fringe Physics Paradoxers and Outsiders.
Physics as Therapy (1) In Praise of Textbooks with Tons of Formulas (or: The Joy of Firefighting).
Physics as Therapy (2) Ploughing Through Theoretical Physics Textbooks Is Therapeutic.
This website shall finally reconnect with its roots – radices.
With the dawn of the new millennium a self-proclaimed Subversive Element has registered a bunch of domains. It was especially fond of radices.net and subversiv.at. Today, all these sites have been re-united and redirected to elkement.subversiv.at. But the site does not deliver on its promising name – I feel it became way too 'professional' recently. Historical content has been filed mostly under Physics (radices) and Art (subversiv). The category life displays some of the matter-antimatter collisions of these two worlds. Which also explains the category of the current article.
The Subversive Site was a Red Padded Cell, with Font Color = White, a so-called creative playground. The Element was aware that 'everybody' could read this but it did not care. The Merger of the sites was inevitable in the end, after a final detour of professionalization – when radices.net suddenly also hosted pages with IT Security links.
I have been a blogger, and I observed the evolution of other blogs: My anecdotal evidence shows that blogs live for about 1-2 years. If they are bound to survive they have to escape the matrix and to overturn their creators. A personal blog or website needs a 'Big' Idea. OK, not really big, but at least a-all-encompassing and abstract enough so that all the authors different threads and lines of thoughts can be silently tied together using this idea's magic glue.
My elkement.blog is relentlessly edited. It was a more philosophical site once, but I aim at following our punktwissen principles now. Articles should be concise, provide value, and perhaps also entertainment. There should be s logical connection between posts and my curated lists should help readers to find something 'useful'.
On the contrary, this site has more or less the same article over and over again – perhaps in disguise and interlaced with technical notes. It is all about my personal keeping the essence of Physics alive and useful for me. Since radices was originally a German-only science and philosophy site, the English version might not reflect this – but in the early articles on elkemental Force (at that time: Theory and Practice of Trying to Combine Just Anything) I recaptured these ideas.
So I do finally accept this – let elkement.subversiv.at have its way. This is elkement's personal site, and its primary topic is How To Learn About Physics And Why This Might Be Useful Or Even Edifying In Very Different Ways.
- Learning physics means to start somewhere in the middle. That's why a first Introductions to Physics lecture is always hard (if the lecturer has some modest mathematical aspirations). You need to look at the same phenomena from different angles, and only after a while – and some work – everything will fall into place. This process and journey of learning is rewarding in itself.
- The more related to mathematical foundations (of physics) a question is, the less googleable the answer is. You can find anecdotes, and examples, science sound-bites for entertainment. Of course you find awesome lecture notes to learn the fundamentals from Feynman Lectures to Landau-Lifshitz – but you need to 'learn' them. In contrary to the mantra of You Just Need to Know Where to Find Something (like: Google for error messages) I believe that really knowing about fundamentals without googling helps a lot with problem solving: You can walk through how a system should work, just using the resources in your head.
- Mathematics purges the brain, and this does not only help with mathematical problem solving. So I believe that the hackneyed problem-solving skills of science graduates are real (albeit it is difficult to assess the self-selecting nature of STEM degrees for people with natural 'analytical' skills). But the caveat it: Years of corporate work, powerpoint slides, office politics, distractions, pressure to deliver ad hoc can erode these skills. I have long-term tested different methods to keep physics knowledge alive and usable - and learned now that science might even provide some evidence, in a sense.
- I have been in 'cyber security' for a while and I have written lots of gloomy articles about our new smart world of automation and where everything (including heating systems) is turned into cloud-based services. Thoughts on all of this is still work in progress, I am working on internal consistency and unambiguity. I came into the world of IT as an experimental physicist, I was applying my training of troubleshooting complex 'analog systems' to digital systems. Despite the myth of crystal-clear 0s and 1s it was often better to treat them as blackboxes. I lacked the typical computer nerd's / enthusiast's background and started late – playing with Microsoft systems and Office VBA and the like. In spite of this Treat-as-a-Blackbox approach I like to understand as much as possible about a system. Yes, I know you cannot understand, yet build, a power plant, from knowing how to solve Maxwell's Equations (yet understand or solve issues in cyber security related to such power plants). Nevertheless, if I have the choice to understand something at all, I'd pick Maxwell's Equations.
Since years I am using an (angry) dinosaur as my web and blog logo. The dinosaur is from another era, and sometimes it cannot deal with 'modern' concepts of our 'smart', 'networked' world. But perhaps, it was part of this world for a while in order to overcompensate.
Now the dinosaur is getting more and more confident that its typical dinosaur activities might be more productive and positive than it thought before.
I have written about all things physics for a long time - mainly on my blog, since 2012 – but I have never been quite satisfied with the result: Too boring for experts, not exciting and popular science-y enough for the 'educated public'. I think the reason was my hidden agenda, an agenda not even obvious to myself.
I wrote about phenomena and subfields I had just immersed myself and (re-)learned about, either because this was very remote from what kind of physics I use on a daily basis, or just because I was concerned with some aspect of it but wanted to complement that with 'more theory' for the fun of it.
In spite of that, I tried to keep a style that somewhat resembles your typical 'science communications', but that was most likely to no avail. Re-reading my old blog posting I don't read so much about 'the physics' as about my own learning process. Or I remember what I actually wanted to write about, but did not – in order to violate the pop-sci agenda - so the result was something in between a learner's notes and sketches of ideas for popular presentations. For example, I (re-)learned Quantum Field Theory after all the news about the Higgs particle and LHC. Both my experimental and theoretical background was in condensed matter physics, so it really took me a while to map what I learned about so-called Second Quantization and many body systems (described in a non-relativistic way) onto your typical QFT introduction that started with Noether's Theorem and Lorentz transformations. Now in order to drive that point home (in a blog posting), to explain what was so interesting for me, I would have had to introduce all those concepts to a lay audience which I considered futile. Or I was just too lazy to learn more LaTex or too hesitant to use equations at all. I noticed, I got on all sorts of tangents when I tried to run a series on QFT – I did exactly what I did not like myself about popular texts on theoretical physics: Pontificate on more or less palpable metaphors about fields and waves, but not being able to really explain anything above a certain threshold of abstractness.
I gave up on my series before I could 'explain' what interested me most: How forces translate into the exchange of virtual particles and how I actually knew about the 'Higgs field giving particles mass' without knowing any more: I had learned about Andersen's mechanism in solid state physics, and Ginzburg-Landau theory of superconductivity. Perhaps that would have been a great example of symmetry breaking and that infamous sombrero hat potential typically used in pop-sci articles about the Higgs field?
I absolutely know that this may sound totally opaque – which is the reason why I only write about it here, on my website in that forgotten corner of the web, rather than trying to turn this into a blog post. Here, I follow my stream of consciousness and don't bother anybody on social media with it. There, I try to be somewhat entertaining and useful.
But even here, I try to write about something that somebody somewhere might be able to relate to, and here 'the internet' comes to rescue: For better or for worse, no matter how seemingly unique, special, and eclectic your hobbies and professional specializations, are – there is somebody somewhere on the net who indulges in the same combination of stuff. So, yes: It seems there is a growing community of hobbyist physics enthusiasts who feel the same and who 'practice' physics in the same way: Professionals with a STEM background who seriously learn about physics in their spare time, like R;&D managers writing textbooks about undergraduate physics or introductions about Quantum Field Theory. Like the IT server admin or the management consulting who write blog posts about what they have (re-)learned in their sparse spare time. Like the retired IT specialists who returns to what they originally studied – physics. Like me, who has an education mainly in applied condensed matter physics and who works as a consulting engineer and IT consultant.
From a down-to-earth perspective, this hobby can be worthwhile and useful: I noticed that it sharpens the mind, even if I don't use that physics and math directly on a daily basis. It's this effect that is makes the hackneyed saying about the 'analytical skills' of physics majors true. However, there is a caveat: Yes, physicists may be good at any corporate job, but I think not to lose you 'analytical edge' you need to practice the skills that originally shaped your mind. I don't know about research in psychology, so this is just my personal anecdotal experience. Living the corporate, inbox- and interrupt-driven work-style and having your mind scattered and distracted my social media does not help. There was a time in my life when I got up at 4:00 AM every day to re-learn physics, starting with Feynman's Physics Lectures. Surprisingly, that investment was well spent. I felt, my IT security concepts become crisper, more concise, and better – and it took me less time to compile them; So the ROI was great.
What triggered this article is my prime example of useful mathematical: While I had some background in QFT there was one subfield in physics I had missed completely: the theory called 'most beautiful', even by sober authors Landau and Lifshitz – the theory of General Relativity (GR). I had specialized in solid state physics, lasers, optics, and high-temperature superconductors, and GR was not a mandatory subject.
But I wanted at least to understand a bit about current research and those issues with not being able to unify quantum (field) theory and relativity. And I can relate to poor consumers of my feeble attempts at pop-sci physics: When I read popular physics books, I enjoy them as long as I have some math background - although I feel sometimes flowery metaphors make it more difficult to recognize something you actually know in terms of math. But when you would have to use new mathematical concepts you cannot understand the metaphors at all. Digression: So it baffles me when people like articles about Black Hole, the universe, and curved spaces but complain about not perfectly comprehensible explanations of more mundane physics and engineering. I believe the reason is that you 'need not' understand worm-holes etc.; so can just relax and scroll through the story, much like watching an illogical science-fiction movie. But mechanical engineering and simple thermodynamics feels like you 'should know it' and 'try a bit harder to understand it', and so it brings back memories of school and tests.
But as I said, there might be small community of people who genuinely want to learn, despite – or because of!! – the so-called hard aspects: Going through mathematical derivations again and again, and banging your head against the wall, until suddenly you understand. Which is a reward in itself, a feeling that's hard to share, and could and should not be shared anyway – in an act of subversive protest against our culture of craving for attention and 'likes'.
So for this community I'd like to share the resources I have picked for learning General Relativity: A set of free resources, each one complete and much more than just 'lecture notes'. Each of them also represents a different philosophy and pedagogical style, and I believe physics is learned best by using such a diverse set of resources.
One can debate endlessly, if and how to introduce the mathematical foundations used in some subfield in theoretical physics. As a physics major, you learn analysis and linear algebra before tackling its applications in physics and/or some mathematical tools are introduced as you go (Hello, Delta function!). I think it does not make such a difference in relation to the first courses in theoretical physics, e.g. learning about vector analysis before or in parallel to solving Maxwell's equations.
I feel it is more difficult the more advanced the math and the physics get, as you have to keep a lot of seemingly abstract concepts in mind, before you finally are presented with what 'you actually use that'. But maybe it is just me: Different presentations of GR seem 'more different to me' than different presentations of special relativity and electromagnetism.
In GR you can insist on presenting a purely mathematical and rigorous introduction of mathematical foundations first – your goal being to erase all false allusions and misguided 'intuitive' mental connections. Thinking about vectors in a 3D 'engineering math' way might harm your learning about GR just as too creative science writing might put false metaphors in your mind.
On the other hand, you could start from our flat space (our flat spacetime) and try to add new concepts bit by bit, for example trying to point out what curvature in 4D spacetime means for curvature in the associated 3D space, and what we might be able to measure.
Some authors use a mixed approach: They starting with a motivational chapter on experiments, photons in an elevator, and co-ordinate transformations in special relativity … and then they leave all that for a while to introduce differential geometry axiomatically … until they are back to apply this something tangible … until more mathematical concepts are again needed.
Sean Carroll does the latter in his Lecture Notes on General Relativity, that are actually much more than notes. He also published a brief No-Nonsense Introduction to GR that serves as a high-level overview, and he manages to keep to his signature conversational tone that makes his writings to enjoyable. Perhaps – if this was the only literature used – the mixed presentation plus digressions into special topics and current questions in physics would be a bit confusing.
But I was still searching for video lectures to complement any written text. A few years ago, I have not found any comprehensive self-contained course, but in 2015 this series of lectures was published, recordings from an event called the Heraeus Winter School on Gravity and Light 2015 – marking the 100th anniversary of Einstein's publication of GR. A nostalgic factoid I found most intriguing: The central lecture of the course by Frederic P. Schuller was given in the very lecture hall at my Alma Mater (Johannes Kepler University of Linz in Austria – JKU) that I received my education in Theoretical Physics, by Heisenberg's last graduate student Wilhelm Macke. Tutorial sheets and video recordings of tutorial sessions can be found on the conference website.
Schuller focuses on the math first, and this was really enlightening and helpful after I used other resources based on mixed intuitive physics and math. The Youtube channel of the event also has recordings of Tutorial sessions, and I found some versions of brief lecture notes. I think this is a must – and unfortunately often overlooked or downplayed in the world of free 'MOOCs'- In order to learn math really, you need to do problems and you absolutely have to walk through every single step of every derivation. It is tempting to just skip the boring proof in a text (that you thought you understood), and it is even more deceptive to watch science videos and believe you understood something. So thanks a lot to my former university to make this course available to the public.
But I was still curious if you can do without manifolds and stuff – without cheating – and I think I found the master of the genre. And again it is a signal from the past (my past): I had looked things up in Landau/Lifshitz Course of Theoretical Physics when I worked at the university. But as the 10 volumes were quite expensive I never bothered to purchase them later. Recently I jumped with glee: Due to whatever quirk in copyright law, the Internet Archive made 9 of 10 volumes available, and I downloaded them all. Browsing through table of contents I noticed that GR was actually explained in volume 2, The Classical Theory of Fields. I am totally smitten by their style, too: Elegant, terse, detached. Much like Dirac's Principles of Quantum Mechanics. And I don't agree with those who say that the explanations are too terse: Landau and Lifshitz try to stay to tangible physics, and they use math in an ingenious way, mathematicians might call it sloppy (like: 'dividing' by differentials to yield a derivative). For that reason, one should consult other resources as well, but I think LL's GR is self-contained.
These books and videos will keep with busy for a while. I also try to interlace it with a bit of QFT again, e.g. by reading Dirac's version of it. My goal for next year is to complete first courses on GR, recapitulate what bit of QFT I learned in 2013/14, and then tackle an actual former specialty again: Re-learning about theories of superconductivity, with an emphasis about how these methods are also used in particle physics.
It might be dangerous thing to announce such grand plans on the web. But next year might be a busy one business-wise, and need to braze myself accordingly.
Once upon a time this category was intended to comprise what I had learned about philosophy. I had even aspired to study philosophy. Then came the dawn of the web and of unconventional philosophers of web culture.
I had also followed common wisdom, and my first FrontPage-generated business website had a section called Philosophy.
What's left of that, or what has been my conclusion?
I believe - in a pang of cheeky self-assurance - that I ought to have my own philosophy. Experience, business and otherwise, should be good for something. My philosophy does not focus on the grand questions of life. I might have had an argument with my former self, the idealistic student of science who aspired to change the world as a physicist, a profession I pictured as a cross-over of hands-on MacGyver theorist-philosopher-mathematician, ad-hoc-inventing smart tools whole mulling upon deep insights on universe and everything.
The unexciting truth is that my personal philosophy is explained best by summing up the different roles I have ever seen myself to take on, no matter what my job title was. None of them was about making profound changes to the world or being any sort of thought leader.
1) The Reverse Engineer
I have been told that I dismantled (tech) stuff already at a time I have no conscious memory of. I wanted to know how things worked, and I found a way to get there. Some of these activities morphed into a career later, the obvious one having been IT Security - the stereotype field for lone maverick nerdswho reverse engineer stuff. Even as a white hat hacker and so-called security consultant you have to indulge in the relentless black hacker's mindset - or you become a security bureaucrat, ticking off checklists and following rules. (Which dies not mean you should not know the rules).
But I could as well have turned into a tax advisor or lawyer, given my pleasure in finding out how such systems work.
I disagree with Keep To Your Core Skills, and I have often used 'wasted my precious time' by 'not delegating'. I hope or believe - delusionally - that 'actually' everybody has this pleasure of finding things out ((c) Richard Feynman). I am wary of marketing (tech) stuff to allegedly dumb or stressed out end-users who don't want to understand anything about underlying technology. Perhaps I am talking to less than 10% of people, but after all this is about my personal credo.
2) The Mediator
One of my first ever fantasies as a child that came close to something like a career was being kind of a negotiator or diplomat. I am not kidding: I dreamt about settling peace treaties between Mickey Mouse and his sinister opponents in his cartoon world.
This has impacted any of my jobs, but it finally surfaced expicitly when a client booked me 'for another mediation', which was in fact the follow-up of a very technical meeting.
I had considered yet another training or degree, in coaching, psychology, or the like. However, I am glad that I never left technology for good (see 1). There is a paradox: People want such 'tech project psychology' services. However, they will not buy it if labelled as such yet happily use them if they come as a hidden by-product of technical consulting.
3) The Communicator
Maybe principles 1) and 2) can only co-exist if you bridge them with a lot of talking. During most of my career 'teaching', 'training', or 'lecturing' had been part of my official duties or a side-project done in moon-lighting fachion. I stopped teaching when I became a moonlightung student again. I have also realized that I am not cut out for
over well managed, structured, quality-assured educational systems. I suck at keeping to my own agenda, and I beg for being carried away by hard off-script questions.
I was not the best class-room teacher, but I think I was good at informal, jam-session-style train-the-experts sessions.
Projects I remember most fondly were those where clients were not only interested in The Tech Guy Who Will Fix Everything but also in my pontifiating on fundamentals, even if that was not required to get the job done. But as I said above (1) - I believe it's always worth it.
4) The Organizer and Automator
When I was a child, I was not called upon to tidy up my room: Not only was I self-motivation to clean it - Mr.Monk-style - but I rather re-organized my cabinets quite frequently. It was Feng Shui of Decluttering meeting obsession with structure, and it has not changed to this day.
I have extended these principles to the virtual world as soon as I had 'data'. Writing a tool, script, program to automate something is second nature. Some sort of software development has always been part of my jobs - just as teaching was, but I found out only recently that I like data analysis and programming much more.
Proficiency with interpreting and manipulating data, and with using or fixing software is part of our culture and should be trained and valued just as other basic technologies and skills. And of course I believe that we, each of us, really needs them! But perhaps it is just my bad luck or my high standards... Every time I just to use and application or service as a normal end-user I end up with low-level troubleshooting.
I am aware of the picture of the obsessed nerd that I have painted here. I don't underestimate subtleties and human nature though. But nowadays soft skills are so often praised to the skies and people with 'big ideas', rather than nitpicking detailed persons, so as Subversive Element the contrarian stance comes natural to me. Even the most empathic coach who tells burnt out IT guys not ot overdo perferctiomism will be very happy if a neuro-surgeon or airplane engineer are totally obsessed with flawless technology.