geordief

What if the gas was composed of different elements with different properties such as perhaps density or charge?

I think (revisiting your first response to the OP) that my implied idea of two essentially homogeneous elements of a system does not really fly. but that , if it did then their state of equilibrium would (as per Swansont?) have to be determined relative to the CoM of the system as a whole (whether the CoM of the two elements was in motion wrt the overall system's CoM) The system's CoM would be changing all the time unless the system was completely uniform. Looking at my later replies I think (embarrassingly) it is best to ignore them now ( as I hadn't taken on board the importance of the CoM of the system as a whole (or any reference frame at all to be honest) I hope that I may have a better idea of (dis) equilibrium in terms of simple motion now. But if I have not then I might have to withdraw from my own thread so as not to muddy the waters. I have had a day to think about it now and if this is still confused then as I say it would be best if I butt out.... Perhaps I used terms inappropriately. When I said "global" I was referring just to a finite system (not the existing universe)... "global" in terms of the system as opposed to its pairs of sub-elements. Would it now be possible/useful to describe such a system in terms of the state of equilibrium of these sub elements to its CoM ?

I have to go out quite soon today . Perhaps it will give me a chance to mull it over

Subject to external energetic input (from outside the system)

If the system is dynamic in an unbalanced way would that mean that a CoM could not be determined? Would such imbalances tend to disappear over time without external input?

A is the relative motion between any two elements of the system and B is the same relative motion measured subsequently. All these measurements can't be measured at the "same time" of course and so the delays might have to be factored in to create any global measurement. Would that work? A is the relative motion between any two elements of the system and B is the same relative motion measured subsequently. All these measurements can't be measured at the "same time" of course and so the delays might have to be factored in to create any global measurement.

Well ,I was thinking along the lines of relative motion. If the system is comprised of a finite number of elements then the relative motion of each element with any (and all) other element can be summed globally to produce a number. (and various sets of "sub numbers") Can this/these number/s be used to give a measure of the disequilibrium of the system as a whole? Perhaps by comparing successive measurements in time? If we release a group of objects ,in space say they will tend to move relative to each other and it may be possible to affect this relative motion by an energetic input from a source that is outside the system ,introducing disequilibrium. If this equilibrium could be measured ,would it be any kind of a function of the energy of that input (the direction would presumably also be important)

Does this exist? If there is perfect equilibrium then one example would be the heat death scenario and so it's value must be zero. But if temperature was the same throughout the system I think the value would also be zero . If the temperature was not the same throughout the system how would one measure this globally ? (and can I call it a disequilibrium of the system ,with a value to represent the degree to which a disequilibrium was present?)

Not mine (and I have two) That seems to be the business (also what I was going to use it for) Yes they are very capable.

Don't have one**....and I want something a little more accurate than that seems to be.( have used that method in the past) **Actually there is a clockface on a smartphone if you need it isn't there?

I am trying to find due South by the Sun ,but realize that it is not as simple as waiting for twelve o'clock and taking that as a reference. Even within the same time the sun will rise ,set and be due South at different times . How can I work this out just by using the lat/long measurements anywhere in the world?

Fact checking and lie detecting don't have to be overdone.They should be used like (imperfect) reference books rather than an ongoing commentary. But it seems good policy not to over repeat the lie and rather to emphasise the truth. I wonder where the repetition of the truism that DT's lies are now up in the thousands and that he can reasonably be called a "stranger to the truth" fits into all that....can that too be overstated? Will his supporters buy into his supposed struggles against what they might prefer to see as an oversimplified kind of truth? (It ain't what you say ;It's the way that you say it)

I don't know the answer ,but reckon you can cast your net wider when it comes to autocrats taking hold of or consolidating their power . I doubt they all have to be especially able ,just up to the task of holding their ground and expanding it when called upon. Wasn't Claudius (of I Claudius) an example as portrayed of one who wasn't cut out for deviousness. There is also always the question of which comes first ,the leader or the gap in the political market. With Trump I fear it is a question of "give him an inch and he will take a mile"

Yes I think I am happy with that now. The curvature remains the same ;so PI remains the same and so the (4d?) volume remains the same. But in the vicinity of the Sun turned Black Hole 4d volumes would have changed alarmingly I guess. Are you still saying (if you were) that the curvature at the place that was the edge of the Sun is the same after the Black Hole has formed? edit: on reflexion I suppose it is ---all the changes of curvature seem to me now to take place within that region.

I am clearly fixated on the notion that mass curves spacetime (a sphere with a radius r will have a different value of pi if it has mass at its centre -different from it would have if it didn't) and I am imagining that this redistribution of mass in the Sun converted magically into a Black Hole should have some comparable effect on the surrounding volumes (pi is related to the volume ,isn't it?) I may have made a leap too far,.(My volume is 3d and these effects -if they apply -are 4d)

I probably need to increase my general knowledge in this area but maybe I can understand that concentrating the density of mass in any one location frees up empty space vacated by the objects in their previous locations.(so that the overall volume is unaffected )

(I feel like a contestant on QI who knows that his answer is going to set off the klaxon, but here goes) What about the volume that has been "sucked out" of the Sun , won't that draw in the rest of the Solar System's volume in so that the "perimetre" of that volume shrinks (imperceptibly) in proportion missing volume ? I expect I am wrong but do you see why I am thinking this?

But would it be ,in theory be possible to take a volume extending out ,say I light year from the Sun ,calculate its volume and then perform the same calculation after the Sun was migicked to its new 3km radius size? It seems impossible to me to calculate the volume in the first place as it is a moving/dynamic quantity (the time at the edge of the volume of the sphere is not the same as the time at its centre (the Sun) But maybe there are ways to do it....are there?

Does "volume of the Solar System" have an actual meaning? If so ,what might it be ?....you seem to be saying it would be unchanged if the Sun was transformed (with a magic wand) to a 3k radius wide body ...

So ,taking the solar system as a whole it would (be almost as if all the space in the Sun except for a 3km radius volume would have simply ceased to exist? Would the volume of the Solar System have also shrunk by the same amount?

No I know it can't normally but what if it did and we could decide on the radius of the new body? If the radius was small enough would it cease to have much effect on the movement of the planets (would they lie outside its region of gravitational influence? ) Is there a limit to how small a radius the "new body" could have? Does its radius depend directly on the mass of the bodies that have been incorporated into it in the first place? Does its radius remain the same provided there are no more additions of massive bodies?

I think "slightly " underplays this when compared with what might have been You are indeed coming from a low base when this result is the near best that could have been hoped for. Like I said ,your post (and one or two others) sent me off to dreamland in expectation of a continuing GOP majority in the House of Representatives in the morning.

To what effect? He has lost the support of the House of Representatives and only marginally increased the GOP margin in the Senate (ie no change). Now he cannot stop scrutiny over his personal and public affairs . Is noone breathing any easier this morning?

You had me down with your pessimism last night. I went to sleep fearing the worst.

Are water vapour levels broadly stable in the atmosphere? Is there any potential for them to rise with increases in global temperatures and impart a feedback effect to any ongoing warming. If so ,what timescales might we be talking about?