sethoflagos

Correct. But relative to it's non-local origin... ?

Stirling Engines don't run without a heat sink. Whatever you did to it, you improved the heat sink.

Including a particle that has receded beyond the Hubble horizon?

You may be correct. I don't know. Hence the question marks in my post. No he didn't. But the temperature JC quoted exceeded the minimum necessary to initiate fusion reactions. Please explain why not.

It's not clear. joigus' interpretation is entirely valid in one sense. However, the only thing leaving a black hole at light speed is what? .... Hawking radiation? Similarly, John Cuthber's plasma fusion reactor is also quite valid. Though again, it isn't exactly going to be 'air' leaving that scenario at light speed. My own post simply suggested a point of view which resulted in air molecules travelling at, and indeed exceeding, c. Maybe not the most interesting point of view to some, but a view nonetheless. wrt your last point, if the air can't escape it's own self-gravitation, it isn't going anywhere fast. Is it?

I'm assuming the process occurs in deep extragalactic space. My understanding is that providing some divergent velocity is maintained, eventually there will be sufficient distance between particles for differential Hubble expansion to drive relative velocities to c and beyond.

Not wishing to nit-pick, but what happens when you blow on a really cold gaspacho? Somebody previously mentioned that faster air velocity would entrain more ambient (cooler) air and up the heat transfer coefficient quite considerably. I wouldn't want to steal their thunder!

Of course it can. Mother Nature has been using ice jacking to turn mountains into sand ever since mountains became a thing. Considering that about 4% of the globe's electricity output is consumed in turning big rocks into little ones; and that those processes are typically 1% efficient (chemical bond energy/total energy consumed); a high capacity, solar powered alternative technology could be of significant value.

This. Some pertinent considerations: Our lungs are not simply compressors. They are also highly efficient heat exchangers and humidifiers. In short, the process is near isothermal, and exhaled breath emerges from our lips (pursed or otherwise), at core body temperature and saturated with water vapour. Skin thermoreceptors sense rate of temperature change rather than absolute temperature. Simultaneous mass and heat transfer can become quite an intense study subject. However, when evaporation or condensation are involved, these processes tend to dominate overall heat transfer rates (compared to 'dry' conductive/convective processes).

1 m^3 of air at stp has easily sufficient mean particle velocity to escape its own gravity well, so providing it's not gravitationally bound to anything else, all you need do is wait a little while for dark energy to kick in. Not sure there's any current limit to the ultimate expansion velocities this could achieve.

In the league table of contributory factors leading to the relative 'mellowness' of French bassoons, I'd put this observation high on the leaderboard. Lower acoustic volume gives lower distortion. I say 'league table' since the tone quality of a musical instrument is invariably the sum overall effect of many design decisions taken in combination. Because of the complexity of multiple interactions between these factors, and the impossibility of adjusting a single parameter without impacting many others, it is entirely possible, for design differences taken in isolation, to produce apparently counterintuitive results, Top of the league table, I'd like to suggest playing style. Traditionally French stylistic tastes are quite distinct from traditionally German styles :- a 1930's Besson Brevete trumpet is consequently quite a different beast to a 1920's Heckel (yes, related to the bassoon Heckels!). The Besson was both designed and played to optimise the appeal to French stylistic tastes, and imho, the playing style is the greater influence. Bend design is definitely in there. They can act as low-pass filters - but there are exceptions. Another very good point. Not all the energy of the acoustic wave is inside the air column. A proportion of it is carried in the shell of the instrument causing complex coupling interactions, and this can have a dramatic effect on tone (particularly for the performer!)

Your point was well taken and agreed with. Your 'harmonic excitation' = My 'brassy distortion'. Different words, same tune.

As you can probably guess from my avatar (from a 50 year-old newspaper article) my musical activities were (until quite recently) mainly high brass. I've a number of Bb trumpets ranging in nominal bore from an 11mm small bore German rotary to a 12.2 mm wide bore Wild Thing; an 11.9mm wide bore C trumpet, and a 12.5mm bass trumpet. The lowest available musical note available in each of them, for any performer, is set absolutely by the 2nd harmonic of the tubing length. The highest pitch available comfortably attainable by any reasonable player is set by the maximum stiffness of their lip. For me, pretty well throughout my playing career, this was a concert high D. This was the case for every instrument I've played over 50+ years (a lot!). Better players than me could usually get a bit higher, some considerably more so. But most serious professionals I've discussed this with (again, a lot) report the same personal experience: they top out at the same pitch on any trumpet irrespective of bore size. So much for personal testimony. Technical literature on the influence of bore size on pitch is hard to locate. If there were such then one would expect papers such as ... An Exploration of Extreme High Notes in Brass Playing (Proceedings of the International Symposium on Music Acoustics (Associated Meeting of the International Congress on Acoustics) 25-31 August 2010, Sydney and Katoomba, Australia (2010) (J. Chick, S. Logie, J. Kemp, M. Campbell, R. Smith)} & Its all in the bore! (Journal of the International Trumpet Guild (USA), 42-45 (May 1988) (R. Smith)) ... both available at https://smithwatkins.com/library/technical-papers.html to at least refer to the phenomenon. Bore size certainly changes the balance between oral cavity pressure and air volumetric flow for a given pitch and intensity - wide bore instruments trade a higher flowrate for a lower pressure compared to smaller bore instruments. This lower pressure amplitude directly results in lower characteristically 'brassy' distortion in passages that are high and/or loud. Hence they sound relatively 'mellower' which was the thrust of your OP. On that point at least we are agreed.

To vibrate a reed (or lip) we need to create a periodic displacement - (generally) to permit the flow of air through it. From Hooke's Law, we know that displacement = force x length / (elasticity x x-section) Only somewhat loosely, we can equate force / x-section to characterise the gauge pressure required to open the air pathway into the instrument. Also, we note that force/displacement is the 'stiffness' term in the analysis of simple harmonic motion, which yields the result that natural undamped frequency is proportional to the square root of the stiffness. Therefore by adjusting the stiffness of our reeds (or lips), we increase both the pressure required to maintain vibration and the natural frequency of that vibration. In short, there is a strong correlation between the pressure amplitude and frequency of the air column. And with a higher pressure amplitude the required x-section area is reduced in proportion to achieve any given acoustic intensity. Hence high-pitched wind instruments tend to feature narrower bores than their lower-pitched relatives. I've skated over (ignored) a huge amount of fine detail here, but the above line of reasoning summarises the underlying physics as I understand it. Hope this helps.

Oil and gas reserves can only accumulate in strata that are at least somewhat permeable. These fluids are free are to migrate towards a low pressure zone within the formation (they are not enclosed in a solid crystalline matrix) and therefore the issue is not accessibility but whether or not the permeability is high enough to support an economic extraction rate. Hydraulic fracturing widens a proportion of pre-existing pores, and wedges them open with appropriately sized 'proppants' suspended in the fracking fluid. It's the geological equivalent of coronary bypass surgery. These 'hard rock deposits' have essentially zero permeabilty. The gold is enclosed in a welded crystalline matrix and therefore the issue in this case is accessibility. In order to get access to the gold particles for any form of liquid extraction process, the rock matrix has to be ground into fine particles otherwise significant contact between liquid and gold particles simply won't happen. Hydraulic fracturing cannot achieve this. Without the initial permeability, you cannot even get the fracking fluids into the formation in the first place other than possibly along pre-existing fault planes. Trying to widen these is probably not a great idea.

+1 While there are undeniably many cultural differences in musical traditions around the world, I've yet to hear, or hear of, any that are not firmly rooted in the natural harmonic series. For neolithic references, Chinese forms are best attested - https://en.wikipedia.org/wiki/Chinese_musicology This clearly predates known weatern forms by many millenia. My favorite example of playing around with acoustic resonances is

Do you play the violin? If you do then you know that you can play chords by multiple stopping. Then you can play out the notes of that chord sequentially as an arpeggio - you still 'sense' the full chord don't you? Then intersperse a few passing notes between the intervals to make the line less 'gappy' and you have a melodic line based on that chord. I think there's less of a difference than you imagine.

Two items to ponder: 1) Notes don't just stop: they bounce around the room as echoes and gradually fade. 2) We have pitch memory. Even when a sound fades into imperceptibility, we can still hold it in memory almost indefinitely. How long do you have to be parted from someone before you forget what their voice sounded like?

We don't need the pitches to sound together to sense the harmonic relationship between them. Also, I don't know about you, but I would find music built entirely out of consonant intervals unstimulating to say the least. Good music tells good stories and good stories need some level of conflict. You can't have a Beowulf without Grendel and his mum tagging along in the background.

Consider this: Per joigus' post, any given structure tends to resonate with a series of acoustic waves that are an integer multiple of some fundamental frequency. That fundamental frequency along with the acoustic intensity gives us an idea of the physical size of the structure, and its proximity. New point: these resonances are related not only harmonically, but also in phase. Therefore if our ears detect a number of simultaneous frequencies that have a simple harmonic relationship and are in phase with each other, then we can reasonably deduce that they came from a single source - perhaps prey, perhaps predator. We could learn to match these complex sounds to precise sources critical to our survival. If we sense either phase shifts or non-harmonic tones within the sound, this indicates that there is more than one source object - useful to know if you are up against a single wolf or a pack. This suggests to me that our distant ancestors may well have learnt to associate simple harmonic waveforms as 'safe' and complex non-harmonic, out-of-phase sounds as 'dangerous'. Not much established science to back up this hypothesis. But it seems a reasonable one to explain why we find frequency ratios of 2, 3 and 5 'pleasant'. And since all twelve notes of the chromatic scale (at least in western music) are constructed from these three ratios (at least approximately), the roots of both harmony and melody seem to follow with some logical consistency.

Because it is a simple case. And because of its simplicity, it's also fairly uninformative. You're not creating any complexity here - just warm water.

Makes sense. "Are you talking about the mover, or that which is moved?"

Sorry. Senior moment. Please substitute 'negative' for 'positive' in the above. (assuming HIP/WIN is the standard)

It isn't a great example to work with. Better would be the case of tree growth in an oxygen rich environment. The occasional forest fire reminds us that the delta G of tree + oxygen to hot fog and ashes is very positive. And yet trees thrive, even sometimes utilising forest fires to suit their own purpose. High positive free energies provide the possibility of multiple simultaneous processes and vastly more chemical diversity than near equilibrium systems. In fact, so much diversity is possible in certain favourable conditions, that long term predictions rapidly become approximate in general trends and utterly speculative in detail. Hence the evolution of life as we know it.

No problem. And be sure to keep us informed of your progress. Goodnight, John.