*[Page last edited 2018-04-12]. Feed for postings in this category.]
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I am mainly interested in – and I ‘do’ – heat transfer, thermodynamics, and energy storage. Here I curate the full lists of my physics posts; there is some overlap with the posts on heat pumps and renewable energy.

On an unrelated note, I am also / still interested in all kinds of theoretical physics and I am self-studying or re-learning Quantum Field Theory and General Relativity.

I was originally trained in: Solid state physics, optics, laser physics, superconductivity.

[2018-04-09] **Can the Efficiency Be Greater Than One?** What is efficiency actually? The ratio of an output and an input energy – however these may be defined arbitrarily. I provide a non-exhaustive collection of examples.

[2018-03-03] **Consequences of the Second Law of Thermodynamics**. Motivated by a paper about Carnot’s efficiency for a machine using Van der Waals gas, I calculated the efficiency for a more general class of substances. But this had not been necessary: Looking at Carnot’s process in a temperature-entropy diagram would have been sufficient. However, I found it intriguing how strong the constraints are that the laws of thermodynamics impose on the properties of materials – so that these functions of state conspire to result in the infamoue rectangle in the T-S plane.

[2018-01-19] **The Heat Source Paradox** – a simple relation between a heat pump system’s key data; yet used in a misleading way in adverts: The worse performance is, the smaller the heat source can be built.

[2017-11-24] **Entropy and Dimensions (following Landau and Lifshitz)**. Just going back to basics – how do the famous physicists introduce entropy and statistical mechanics in general?

[2017-11-01] **The Collector Size Paradox**. ‘Collector harvest’ does not change much if we only use half the collector. Perhaps counter-intuitive but explained by the characteristics of heat exchangers connected in series: Especially if one of the heat exchangers (in the tank or collector) is already much superior to the other one, it does not help to optimize the good one further.

[2017-09-17] **Tinkering, Science, and (Not) Sharing It**. Inspired by a paper on the arxiv – filed under Popular Physics: PVC Polyhedra are a thing.

[2017-08-17] **Simulations: Levels of Consciousness**. Simulating ‘physics’ is the basis of a hierarchy of factors to be considered – in simulations of real-live heating systems.

[2017-07-14] **Heat Transport: What I Wrote So Far**. A list of all my blog posts focussing on heat transport, plus short summaries: Heat transfer and energy storage in our heat pump system, in ground, in ice. Analytical solutions versus numerical simulations versus maverick’s heuristics.

[2017-06-17] **Spheres in a Space with Trillions of Dimensions**. Nearly all the volume of an N-ball with a large number of dimensions is concentrated in an extremely thin shell below its surface. Boring textbook stuff – but I found this particularly intriguing in my first encounters with statistical mechanics a long time ago.

[2017-05-08] **Ploughing Through Theoretical Physics Textbooks Is Therapeutic.** Meta thoughts on my life-long re-learning of phyiscs, triggered by an article about psychological research: Corporate speak makes you dumber, thus I needed to replace it by mathematical derivations.

[2017-05-02] **Simulating Peak Ice**. Continued from last post – comparing measurements of the level in the tank with simulations of the evolution of the volume of ice. Simulations comprise a model of the control logic, the varying performance factor of the heat pump, heat transport in ground, and energy balances for the hot and cold tanks, and the heat exchangers connected in series.

[2017-04-08] **Mr. Bubble Was Confused. A Cliffhanger**. The very simple physics of temperature-dependent density caused some confusion – our automated level sensor underestimated the volume of ice in the melting phase.

[2017-02-22] **Ice Storage Hierarchy of Needs**. Mulling upon ‘Peak Ice’ in our heat pump system – and detailed simulations versus simple energy accounting.

[2017-01-07] **On Photovoltaic Generators and Scattering Cross Sections**. A physicist’s musings about the unit used to characterize solar panels’ peak power: kWp.

[2016-12-03] **Learning General Relativity**. Latest physics self-study project – my list of resources and why I picked them.

[2016-11-03] **And Now for Something Completely Different: Rotation Heat Pump!** An invention by an Austrian start-up that would make for an awesome example in physics and engineering thermodynamics textbooks: The pressure gradient is created by centrifugal forces!

[2016-09-18] **Re-Visiting Carnot’s Theorem.** From the theory department: Why can’t there be any heat pump / heat engine better than Carnot’s reversible machine? A closer look at the proof by contradiction.

[2016-03-01] **Rowboats, Laser Pulses, and Heat Energy (Boring Title: Dimensional Analysis)**. Re-visiting heat transport and heat diffusion length, this time only analyzing dimensional relationships. I introduce the concept of dimensional analysis by answering the question: How does the speed of a rowing boat depend in the number of rowers?

[2016-02-08] **No, You Cannot ‘Power Your Home’ by One Hour of Cycling Daily.** All the physics in this post is the relation of energy and power: kWh = kW times hours. Unfortunately it seems there is a need to harp on this.

[2016-01-22] **Temperature Waves and Geothermal Energy**. Solution of the Heat Equation, based on the simple assumption of a harmonically varying surface temperautre, plus a superimposed geothermal gradient. The results can be used for cross-checking the value of the thermal diffusivity of ground.

[2015-11-25] **Peter von Rittinger’s Steam Pump (AKA: The First Heat Pump)**. An account of the 19th century invention, based on the original German research reports.

[2015-09-29] **Heat Pump System Data: Three Seasons 2012 – 2015**. Brief summary of last season’s performance, plus back-of-the-envelope estimate of economics.

[2015-06-04] **Lest We Forget the Pioneer: Ottokar Tumlirz and His Early Demo of the Coriolis Effect.** Finally two science geeks did a careful experiment – proving that vortices on either hemisphere rotate in different directions. I just like to point to a pioneer who did such an experiment long before the social media era – in 1908.

[2015-06-01] **An Efficiency Greater Than 1?** The Coefficient of Performance of a heat pump is much greater than 1 which is due to the definition, omitting input ‘ambient energy’. The rather high factor gives proof of the fact that heat pumps operate well above absolute zero.

[2015-04-21] **How to Evaluate a Heat Pump’s Performance?** Definitions of performance indicators and how to determine them – comparing alternative methods, based on sensors available (Coefficient of Performance / Seasonal Performance Factor). Bonus: Cute math puzzle as the comparison boils down to: When is the ratio of averages equal to the average of ratios.

[2015-04-01] **Ice Storage Challenge: High Score!** The ice cube, generated by our heat pump, stopped growing at about 15m^{3}. About 10m^{3} of water remained unfrozen. Toying with theories and the differential equation of heat transport we came up with an explanation.

[2015-02-14] **A Sublime Transition**. Phase transitions between water, vapor, and ice: Last winter’s viral trend of freezing boiling water in mid-air, and discovering that scientists discuss such effects to this day.

[2015-01-28] **More Ice? Exploring Spacetime of Climate and Weather.** A simplified simulation based on historical weather data: A heat pump uses the sensible and latent heat in a tank of water and that energy is replenished using an unglazed solar collector: How large should this tank be so that it would hardly ever freeze completely in typical Eastern Austrian winters?

[2014-10-16] **All Kinds of Turbines**. Again some back-of-the-envelope cross-checks, this time related to hydro power.

[2014-10-04] **Pumped Heat from the Tunnel**. Cross-check of numbers for a large heat pump system, from a press release. The heat source is water from a tunnel.

[2014-06-22] **Grim Reaper Does a Back-of-the-Envelope Calculation**. Some crude estimates related to the physics of scything – and why it might be so exhausting.

[2014-02-16] **How to Introduce Special Relativity (Historical Detour): **An alternative way of understanding SR – found in my favorite ancient text book.

[2014-02-05] **Non-Linear Art. (Should Actually Be: Random Thoughts on Fluid Dynamics)**: Why is fluid dynamics hard? Where does that infamous non-linearity sneak in?

[2014-01-05] **In Praise of Textbooks with Tons of Formulas (or: The Joy of Firefighting).** Why I read theoretical physics textbooks in the morning.

[2013-12-22] **Student Friendly Quantum Field Theory**. Review of Robert Klauber’s excellent book.

[2013-12-02] **Using Social Media in Bursts. Is. Just. Normal**. On modelling the behavior of so-called intelligent life-forms using analogies from physics. Bonus: My anecdotal experience.

[2013-11-25] **Mastering Geometry is a Lost Art**. On Newton’s geometrical proof of Kepler’s laws.

[2013-11-15] **Revisiting the Enigma of the Intersecting Lines and That Pesky Triangle**. Following up on the puzzle – and correcting my earlier proposal. Epic comments!

[2013-11-04] **Learning Physics, Metaphors, and Quantum Fields.** A bit of path integrals and symmetries, introduced by lengthy ramblings on metaphors in physics.

[2013-10-17] **Hyper-Jelly – Again. Why We Need Hyperspace – Even in Politics**. Since my post on phase space was appreciated nearly only by physicists and mathematician, I have tried again – starting from a metaphor concerned with Austrian politics.

[2013-10-10] **On the Relation of Jurassic Park and Alien Jelly Flowing through Hyperspace. **I tried to explain Quantization using an uncalled for detour through phase space, pop-sci chaos theory memes and indulging in statistical mechanics.

[2013-09-29] **May the Force Field Be with You: Primer on Quantum Mechanics and Why We Need Quantum Field Theory** is a summary of what is popularized often, wave-particle etc., but I add some field theory at the end – and I start from a very down-to-earth field.

[2013-09-17]** Space Balls, Baywatch and the Geekiness of Classical Mechanics**. Why I believe that classical mechanics is as geeky as Quantum Theory – just view it through the lenses of an alternative, more spooky, mathematical representation.

[2013-09-11] **And Now for Something Completely Different: Quantum Fields!** The trailer of the series on Quantum Field Theory.

[2013-06-03] **Theory and Practice of Trying to Combine Physics with Anything **On the usefulness (or not) of models borrowed from physics in other fields.

[2013-04-03] **The Falling Slinky and Einstein’s Elevator**: It’s fascinating that it is not easy to explain seemingly mundane classical mechanics!

[2013-03-17] **The Twisted Garden Hose and the Myth of the Toilet Flush**: On Coriolis force.

[2013-03-13] **Intuition and the Magic of the Gyroscope** – Reloaded: It seems that *gyroscope* is one of the most searched for terms on this blog. I dish what you long for, readers!

[2013-02-09] **Physics / Math Puzzle: Where Is the Center of Mass?** An intriguing puzzle and my first (later corrected) proposal of a solution.

[2013-01-28] **Random Thoughts on Temperature and Intuition in Thermodynamics**: I could not resist to just let the hype about negative temperatures pass by.

[2013-01-06] **Why Fat Particles Radiate Less**: Thinking about the LHC – though some of my Facebook friends found better interpretations of this title.

[2012-12-30] **Quantum Field Theory or: It’s More Than a Marble Turned into a Wiggly Line.** A brief summary of the differences between Quantum Mechanics (think: Schrödinger’s Cat and Wave-Particle-Dualism) and why we need QFT.

[2012-12-05] **Is It Determinism if We Can Calculate Probabilities Exactly?** Quick primer on interpretations of quantum mechanics – and why I consider it problematic to use ‘philosophical terms’ in physics.

[2012-11-20] **Are We All Newtonians?** How intuition may fail us, even when dealing with alleged simple classical mechanics.

[2012-11-02] **Einstein and His Patents** … his refrigerator patent in particular.

[2012-10-23] **111 Years: A Shining Example of Sustainable Product Development?** I missed the most amazing light bulb’s birthday – the least thing I could do was to write a post.

[2012-10-04] **Physics Paradoxers and Outsiders**: My take on fringe science, inspired by Margaret Wertheim’s book Physics on the Fringe: Smoke Rings, Circlons, and Alternative Theories of Everything.

[2012-09-05] **The Spinning Gyroscope and Intuition in Physics**: Do we understand the gyroscope really? Marveling at Feynman’s explanation and new(!) papers on explaining it.

[2012-08-30] **Sniffing the Path (On the Fascination of Classical Mechanics) **Trying to demonstrate that classical mechanics is geekier than you think, borrowing terminology from Richard Feynman.

[2012-08-12] **Unification of Two Phenomena Well Known**: Electrical and magnetic fields are actually two aspects of the same thing (special relativity).

[2012-05-10] **Why Do Heat Pumps Pump Energy so Easily?** Brief (yes, really) explanation how a heat pump works.

[2012-04-29] **Stupid Questions and So-Called Intuition**: On learning physics.

[2012-03-28] **I neither Met Newton nor Einstein** Re: The Trouble with Physics by Lee Smolin.

[2012-03-25] **Real Physicists Do Not Read Popular Science Books** Are pop-sci books useful?