studiot

A substitution test with a friend's monitor is best if at all possible, many also laptops have a monitor output socket of some sort. If it is a separate monitor you may be able to test it with a friend's computer. Yes there are , or mostly were, computers, PC and Apple that ran the mouse from the monitor, but they are dying out so unless yours is one of these, most computers have no direct electronic intraction between mouse and monitor. This is a good time to ask you to tell us more about the computer in question and the symptoms.

An interesting application of art in science by Leonardo Da Vinci from the BBC http://www.bbc.co.uk/news/health-28054468

There is more to it than trilateration v triangulation. In order to obtain a 'position fix' you require the intersection of a minimum of two intersecting position lines, in 2D, and 3 lines in 3D. A position line is provided either as a distance (circle) or direction from a known point, thus 2 or 3 known points are required. The known points may be either actual points in 2D or 3D space or they may be projections of actual points onto a standard surface, eg a sphere. Calculation is then performed on the triangles, rather than quadrilaterals or other figures to establish coordinate differences. These triangles may be spherical triangles as in the case of astro work or they may be euclidian, corrected for relativity. The use of additional known reference points and position lines provides multiple estimates of the fix, which may be weighted and adjusted statistically to improve accuracy.

There is one vital fact missing from your list. At what temperature is the bar 500mm? (you will also need to look up the temperature coefficient of expansion of steel.) Then calculate the maximum and minimum possible measurements, given the other data.

No, offence Hazel, but check the spelling in your post against swansont's steganography Stenography! As to GPS, I'm surprised no one has mentioned that it is not possible to perfectly match 3D space coordinates, as used by satellites to the surface of the Earth, on a flat 2D map. This has to to with ordinary geometry and nothing to do with relativity. Also transmission to the receiver is not perfectly known, and affected by conditions and the terrain. We used to call this 'ground swing' in the old days. You can find lots about it on google.

Even if you can't do the problem, you could tell us what you understand by adding more lamps in series. You might also like to think about what happens to the power source voltage when you add lamps. Remember voltage and current are connected by someone 's law.

I did note in post#24 that most of the definitions and much of the maths applies only to finite systems. The question arises is the universe finite or infinite, and, if infinite, how do you treat it? Let us say you calculate a finite entropy 'increase' of S. Can you prove that infinity plus S is greater than infinity? (Sorry I can't present maths symbols from Dundee.) Now let us say you have a system, finite or infinite, and you use S = k ln(w) to calculate the total system entropy. ln(w) is a function that has no upper bound so as w tends to infinity ln(w) does not tend to a finite limit but increases without bound. So does an infinite system have infinite entropy? Can a finite system have infinite entropy? Consider in say the Morse curve where w is a discontinuous independent variable, below a certain level, but continuous above, where there must therefore be an infinite number of energy levels. Consider also Caratheodory's (hope I spelled it correctly) version of the second law: For any equilibrium state there are nearby equilibrium states that are inaccessible to the system. I said I was happy to discuss entropy, but I don't see how the above is relevant to reversibility.

The book I referred to in post#8 should provide the non expert with a real feel for the subject, without needing to know the intricate details of the physics, via the history of who measured what and why, the proposed explanations, and what Katy did next.

+1 for an honest question, honestly put. The first measurements contrary to the accepted science of the day led Einstein to his theories. He subsequently made several changes (refinements ?) to particularly the General Theory, in the light of later measurements. Both his theories also yielded predictions that were tested and found accurate. In fact, no one has ever found measurements contrary to the final versions. However it is also true that there are other more complicated potential explanations that also fit the known facts. During the last century there were even more competing theories but several failed as a result of some new measurement. There is a fascinating book just out by the Professor of Astrophysics at Oxford University that charts the history of relativity. The Perfect Theory Pedro F Ferreira

Thanks for the reply, presume your essay is now long sent in. I wouldn't recommend playing politics with what is really your future knowledge base. OK so your prof has poor English, but there are a great many very, very clever foreigners so better politics would be to find a way to get the best out of him. You would gain more this way in the long run. Go well in your studies.

Once again you are either misunderstanding standard thermodynamic terminology or you are redefining it to terms of your own. This is logical nonsense since including the heat source as part of the system leads to the inescapable fact that the heat transferred from the surrounding to the system equals precisely zero (First Law). This, in turn, leads to the inescapable conclusion that whatever the process, whatever the final system and surroundings the entropy change is always precisely zero (Second Law).

In response to post#25 Since both your answers were totally flippant, I see no point discussing this topic further with you.

@JC You made two substantive points, so dealing with them in order; This thread is clearly labelled with the term thermodynamic, so surely it is reasonable to employ thermodynamic terminology. Introducing terms from mechanics is particularly difficult and confusing since within that system perpetual motion is admissible. Note I did not say perpetual motion machines. Force is an important quantity in mechanics, but very minor to totally unimportant in thermodynamics. So can we please stick to conventional thermodynamic terminology? As to you second point, I noted that you replaced the variable, entropy, with another, enumeration of energy levels along with a constant. Since you did not define your new variable or display a chain of mathematics leading to its relevance I regard the variable entropy as still undefined in this thread. Now I will happily widen the discussion to entropy and the connection between the Boltzmann equation and classical thermodynamics. The first thing to note is that the enumeration variable is not a continuous variable, so there is a mathematical issue in employing it in connection with classical continuous variables, calculus and so forth. Yes it can be overcome but care is needed. The second thing to note is that classical thermodynamics does not attempt to offer calculation of absolute entropy of a system in the same way as statistical mechanics. The Boltzmann formula refers to system entropy, whereas the Clausius one refers to entropy difference. The distinction is rather like the distinction between voltage and voltage difference. There is a further difficulty employing an extensive state function like entropy in that the definitions, open closed and isolated only make sense for finite systems. Both S and delta S have singularities at zero and infinity. I think that is enough to be going on with if you are serious about a sensible technical discussion.

"What do we think?" Too long and too dense for an internet forum, IMHO, no offence meant. How about a potted appetiser?

Well English is my native language and I believe that what I wrote was good English. However I will rephrase it for your convenience. I agree with your statement, " true science does not discount any possibility". But use of this agreed fact must be contingent upon whatever is being considered for counting being actually possible. I also think that others find, as I do, that most of your statements concern impossibilities or conjectures. I am suggesting to you that this might be the reason for their reaction to your statements. go well

I don't know if you were addressing my post #10 in your edit to your last post #11, but how about responding to it, since I actually managed to find a truthful statement in one of your posts?

@JC Why is it that you post incorrect statements, using incorrect definitions of basic thermodynamic terms in your post #7 and then proceed to mock my 'lack of background knowledge' (your post#19). An open system allows both energy and mass exchange across the system boundary. A closed system allows energy exchange, but prohibits mass exchange. An isolated system prohibits all exchange. So you were using incorrect terminology when using your dewar flask analogy to lambast my sincere attempt to engage in polite discussion rather than fully expose this misuse of terms. The whole purpose of this thread stemmed from my desire to further the cause of avoidance of such misunderstanding of what you call background knowledge and I call first principles, before going on to more advanced and more difficult matters such as entropy.

Correct, but I think you will find others are disputing that much of what you say is possible.

Well, if your organisation needs a consultant to spearhead your investigation, let me know.

Chocolate is complicated. Yes it may fail in brittle failure at room temperatures in bending but it will more than likely squash rather than fragment to powder under compression. I have never tried triaxial tests on it though.

The margarine and butter industries have done considerable research on this subject related to fats, which also undergo pseudo phase transitions. Chocolate is a large % fat after all. But all are mixtures, so do not exist in single phases in the same way as pure substances.

Ken, your first post shows a curious mixture of fact and fallacy. Yes energy has to do with motion. No you do not need energy to change direction od motion. Yes energy and force are different independent quantities, you can have either without the other. Yes they are often connected through motion. But that is not the explanation you seek. My best advice is to read the delightful monograph by Professor Peter Atkins of Oxford University 'Four Laws that drive the Universe' Three of his four laws discuss physical phenomena that introduce and define a physical property. The second of these is energy and he give clear explanations to all my above statements and much more besides. The book does not require significant knowledge of mathematics.

I am sorry the experts here have declined to help. I cannot paste links from this computer but I googled food rheology and chocolate rheology and found lots. Happy surfing

Why are so called experts so condescending? Flow system thermodynamics, is 'open'. Do you not know this or is it only those with limited knowledge? At least I am prepared to admit my limitations. An expert should surely be able to explain his words of wisdom and back them up with rational argument, rather than personal attack.

So entropy is undefined, since you have defined neither k nor w, from first principles. Further it is incomplete because I choose to examine non closed systems, and a non universal definition is just that, non universal and therefore certainly non fundamental.