J.C.MacSwell

With sound you have a preferred reference frame, that of the rest frame of the air.

Long live the King!

Negentropy http://en.wikipedia.org/wiki/Negentropy

So you are describing a frame in uniform motion as inside a vehicle in uniform motion. But not everything inside a vehicle is necessarily going the same speed or direction...things can be in motion, both uniform or otherwise with respect to this frame. So is everything inside the vehicle still in this frame? The driver? The wheels? The passenger in the back that is switching seats?

It got a little OT, but it was to do with what can be considered "in a frame". The accelerations discussed were more with respect to the frame, not due to the frame itself accelerating. If you have a link to a definition of being "in a frame" that would be helpful. I do not believe a definitive one exists, leaving it somewhat ambiguous and depending on context.

Physics is not the problem. It is the definition of what can be considered to be in a frame.

I understand what you mean, but to me (present interpretation) they are in each others frames, but do not share the same rest frame. The two observers still exist in each others time and space. I think sometimes people learning SR get some mysterious sense that they are separate, and it is reinforced when they are told they are not in the same frame as each other and misinterpret the context. The frame is not accelerating. The object at rest (zero velocity) with respect to it's coordinates is. An inertial frame is said to be one in which physics takes it's simplest form. Obviously this does not just refer to the physics of fixed objects so context is everything. I think I misinterpreted this (bolded). So you are saying an accelerating object is not in an inertial frame, not even one that it has zero velocity in. I'm OK with your interpretation, though I don't think it is universal in physics and do not see where it is taught or defined (prior to here) It seems unnecessarily non intuitive to say my arm is not in the frame of my body, or something inside a rocket is not in the frame of the rocket. At other times it makes more sense, though using phrases like "at rest in or "with respect to" makes the context more clear.

"However, a frame of reference can always be chosen in which it remains stationary" Choice implies that there are others in which it does not remain stationary Too me that example just states that you can choose an inertial rest frame for an object that is at rest (no external forces) Not sure how that summarizes what you quoted, but in any case this contradicts your definition for an accelerating object not being in any inertial frame... ...since you can always choose an inertial frame that it would be stationary with respect to the coordinates of (zero velocity, regardless of the acceleration) Sorry if this seems picky, that is not my intention, but to me "not in a frame" needs context, and I don't believe everyone automatically realizes you mean "not fixed in the coordinates of" or even "not at rest in". At times in can be inferred from the discussion (easier with your peers) but at times it seems misleading or implies something has somehow moved outside of a frame.

I've seen that. I don't see where it would support your definition of what is in or not in.

So "not in that frame" simply means not at rest and not accelerating in that frame? Even while accelerating, there exists an inertial frame with respect to which I am at rest, though only instantaneously. So from your definition I am not in that frame? "In that frame" means fixed in that frame? Can you provide a link or source for that definition? Is it just the context you and your peers always use or is it strictly defined in physics?

To me this seems more than a little ambiguous and a source of confusion (it can't be just me) Is there a link or source for that definition? Can you explain why something that is clearly there is said or implied not to be there? My use of of the phrase "in the frame", would include everything of interest, including any Mack Truck in my vicinity accelerating or not. Can you tell me why this is wrong? I know that "in the frame of the truck" would imply something different but that is true whether the truck is accelerating or not. Inertial frames are generally chosen as they simplify the physics, and not just linear transformations. Others are chosen because they simplify the math, at the price of adding pseudo forces to the physics. If your definition is correct for physics there must be a reason for it. What is the use of it? Why is something that is accelerating said to be not in the frame?

I don't understand what you mean when you say this. Can you not describe accelerated movement with respect to an inertial frame?

What do you mean by this? NOT share the same inertial rest frame? (then yes)

I think that's correct but it's usually more in terms of SR where displaced particles in different rest frames, at speed wrt each other, disagree on simultaneity. So if something happened to each instantaneously for one the other would not agree that it was instantaneous. I'm not sure if the fact that they rate aging differently in different gravitational fields would be a problem as they would both agree on that, so they could presumably agree on what would be instantaneous or simultaneous in the right circumstances (Perhaps if the Earth and Black Hole were at rest wrt each other ??)

I think this can be misunderstood. They are both in an infinite number of inertial frames (as well as other frames). They do not have the same shared rest frame (at least not an inertial one), but are still in existence in each others, even if their inertial rest frames are constantly changing and are not the preferred frame to consider their movements in. I think in strong gravitational fields inertial frames can be only defined locally, so something far enough away might not be able to have a position defined in that frame, but I don't think this applies here (not significantly)

I must have missed that article back in 1976. Amazing that it would have not surfaced earlier after invention in 1922. I don't expect science to explain it until perhaps 2022, but since it works so well I fully expect it to take off at that time and everyone will want one knowing that it is possible, and doesn't just merely work, as it did 100 years earlier. Ok, more seriously: Moving air causes friction, heat (or thermal energy waste) and expanding (throttling) compressed air at ambient temperature causes cooling, so some inefficient process may allow this to happen.

At equilibrium, assuming one phase, and knowing the gas, liquid or solid involved, doesn't the temperature tell you a lot about the internal energy in most cases? Even if they are directly linked to kinetic energies, are they not measurably linked to the others?

Nature can in fact maintain a "cold hole". Usually we expend less at the start by taking advantage of topography, but we do build dams and harvest hydroelectricity. Very inefficient when you look at the whole process, but the energy is "free" and being wasted otherwise. So if that was what Tesla was thinking the principle is sound...and of course in accordance with the laws of thermodynamics. A heat engine of sufficient size could produce power from the Sun, even somewhat indirectly using diurnal heating and nocturnal cooling or barometric pressure fluctuations. The trick is concentrating what is "free" in a way that you can do it economically.

Although it is a little vague, I'm basing my opinion on this line where I believe you were quoting Tesla: "We would thus produce, by expending initially a certain amount of work to create a sink for the heat or, respectively, the water to flow in, a condition enabling us to get any amount of energy without further effort"

In this context it is absorbing and dissipating energy rather than transmitting or rebounding it.

R1 and R3 are in parallel and together are in series with parallel R2 and R4.

Tesla's idea won't work. He was hoping for a perpetual motion machine.

Not sure about psychological effects but damping vs non damping +resonance would have something to do with it in some cases. You may have been in a local peak area to feel it.

If you're starting to think Thermodynamics is an unfair game you are in very good company. http://en.wikiquote.org/wiki/Thermodynamics You can use ambient temperatures to drive a heat engine as long as you have a sufficient heat sink. No violation of thermodynamics, and in fact they are theoretically more efficient than the equivalent heat source. Unfortunately, you need an indefinite "re-source" to keep it going indefinitely. The same rules apply. Without a heat sink the ambient energies are useless, as are the heat source energies without the ambient. Useful energy diminishes in every case. Even ideal reversible processes don't happen in reality. We just try to get as close as we practically can. At every point entropy is increasing so there is no point in tricking yourself into thinking you have beaten the system. It's like a version of an Escher Waterfall: http://www.escapeintolife.com/wp-content/uploads/2010/08/Escher_Waterfall.jpg In reality it doesn't happen. You can't point to even one point in time in the system where entropy is decreasing so there is no point in pondering the illusion of the whole thing.

Greater complexity or not, the energy represented by your sandwich was at lower entropy earlier than later. Complexity and order are both analogous and related to entropy but they are not the same thing.