studiot

Does anyone remember the long thread about the mechanism of the 'tin can telephone' (made of two tin cans and a taught lenght of string) we had not too long ago ? Remember also that the mechanism is quite complicated. Here also we have a complicated mechanism. Firstly note the the OP did not say he was vibrating the glass or the glass wall. He said Now that finger introduces a point compressive load on the glass wall, which moves around the glass. The the glass wall acts as a very slender strut under the moving compressive load. On account of the curvature the wall bends slight inward where the finger acts and relaxes elastically again as it moves on. The inward movement slightly decreases the total volume of the container so the water is squeezed slightly upwards locally. Once the finger has moved on and the glass wall has relaxed back to its normal position, the water surface is (again locally) too high up the side of the glass to be in equilibrium under gravity. So gravity pulls it back down again. The falling water moves horizontally away from this point. This produces a rising and falling of the water surface locally, which in turn results in periodic water movements horizontally against surface tension, (which acts horizontally). So these pulse moves across the surface reflecting off the opposite walls creating and maintaining the standing waves observed if the frequency of rotation around the glass is in phase with the resonant frequency of the water. I remember our old A level Physics teacher demonstrating resonance using a 2kg hanging weight struck periodically with a knotted handkerchief. So as you see the phenomenon is quite complicated, separate consideration being needed for all the different forces involved, both horizontal and vertical.

There's no magic in it. Have you abandoned an analytical solution ? As swansont has told you I cannot do your work for you, but I see that you have been trying, even though you have not posted your complete efforts. It is always a good idea to post these as we can then see where you are either stuck or have gone wrong. So here are some analytical hints. 1) Look at triangles SDT and DVT and write out the sine rule for each. 2) Note that DT is common to both these triangles so by comparing (equating) expressions for this common side you can obtain one equation. I obtained one involving the angle have labelled A, the angle you have labelled X and the angle 18. 3) Now look at A, X and 18 from a geometric point of view. They have a geometric relationship in triangle DTV 4) This gives you two equations in 2 unknowns to solve. Let us know how you get on.

Thank you +1. I had been really hoping that someone would look more carefully at my list of 4 questions to reach the answer,because it is not 'optimal' in that my questions will not work in every case. There is, however, an 'optimal' set of 4 questions that will work in every position. This set corresponds to a true 'binary search' where you halve the number of possibilities at each step. This is no accident. A 4 x 4 cell board has 16 = 24 cells. So it takes 4 binary digits to uniquely label each cell. And 16 is the maximum number of cells you can uniquely label (identify) in this way. Does this help ?

Yes, +1 By direct drawing, (ie construction) I very quickly made the result about 10o last night. Sadly this is not enough. As can be seen from my sketch the four angle equations alone are not independent so there are infinitely many solutions, corresponding to the infinite many positions we may place D between S and V. The problem is, however, solvable using the extra information that ST = DV. The fact that we do not need to know its actual length shows that we are not in the ambiguous sine rule case and that the problem is solvable without knowing this length. Genady's constructive solution using isoceles triangles is creative.

Sigh! This paragraph makes no sense and is totally irrelevant to the thread question. How can information entropy decrease ? Happily this question was ably demonstrated by @joigus direct calculation on my example, something you had ample opportunity to perform yourself, but chose not to do. This is now the third thread where you have avoided engaging in direct questions or comments about your posts, the other two being your wave thread and your experiments and information thread. This is a pity because in the case of the latter I supplied a direct answer to your chemistry question ( which you have not acknowledged). My answer here in this thread, without engaging set theory, is that as information entropy and information measure are not exactly inverse functions but reverse ones or contravarient onces, then as information measure increases (which it must do as one progresses through a calculation so you end up with more information (the result) than you started with) information entropy must decrease. I have also pointed out (and once again you have not responded) that one limitation to this would be further times when the calculation is run, you already have the answer.

I'm sorry, this opening post is so full of incorrect data as to belong in the trash can and put behind us all as quickly as possible. Can I suggest that you revisit your zero thread, where you might have asked a serious question but don't seem to have been back to consider the answers?

https://www.bbc.co.uk/news/education-60491719 Whilst I can see the need for at least some knowledge of these subjects, I consider this approach far too heavy handed. How would a modern day Ramanujan ever get into a UK university ? Or how about someone who wishes to follow a Masters in Hairdressing ?

So why did you 'aim' such personally abusive remarks instead of answering the question you still have not answered? So you are now shifting your ground, when I point out that the energy or entropy involved in computation (and it does not matter how long or how much) can vary simply because obtaining the result can take different routes. This is not the case with thermodynamics which is founded on the idea of route independence between defined states.

Thank you for a thoughtful, pleasant and cooperative reply. An example to everyone. +1 I don't think I said that there is no cost to storing (and retrieval) - certainly I did not mean to imply that. Here is an admitedly extreme example. Let us suppose the computation takes 3 hours of running the met office supercomputer and the output result is the temperature at 9 pm in Trafalgar Square at 7.3oC. How much resource does it take to store the result compared to how much it would take to exactly repeat the calculation ? I will certainly look at your references with interest.

@Riba Have you seen this ?

Ok. Maybe tomorrow if I can find the time. p.s. Please state exactly why you think building a computer that does nothing, so doesn't generate any heat, is a counterexample to what I said. I don't see this as a difference difference between thermodynamic entropy and Shannon (or Hartley) entropy or any statement about the Second Law. Since you don't want to answer the question, for my part I think the most significant difference is that Once you have perfomed a computation and incurred whatever resource price the universe exacts in terms of energy, entropy etc, you do not have to incur those costs again since the result of that computation is then known, the next time it is required. However in thermodynamics the universe exacts its pound of flesh each and every time the given process is run or occurs.

+1

Excellently thought out and presented post. +1 I see from the map that Russia has now secured its land route (corridor) to the Crimea.

No. The name of this website is ScienceForums. As I understand the structure and rules, Serious subjects have a scientific aspect and many of these subjects are given a special section within the website for discussion of these scientific aspects. Religion is one of these. Such discussion involves criticism used in its proper meaning. The proper non colloquial meaning does not involve disparagement. This website also has a section where you can say "I hate Jesus, your cat, Allah, Buddha, big band music, the colour of your tie, or whatever" That section is called "The Lounge". However such proclaimations are unlikely to gain you much traction as they bore most scientifically mined folks. In fact the whole subject of religion bores me personally, and I would prefer it scrapped altogether. But I accept that there are scientific aspects of it, so I accept that others want it even if I don't, so long as they discuss the scientific aspects of it. The purpose of moderators is to moderate and the general concensus, not just my own opinion, is that they do a pretty good job for no reward. I personally have seen them listen to well reasoned requests and put a good deal of their own time and collective effort into making changes, where they have the power to so do. It should be acknowledged that they do not always have this power over matters which are set by the site's owners.

What an excellent post all round. +1

Do you deny the mathematics of the identity transformation ? Or do you deny that a computer that can perform exactly one transformation (the identity transformation) is a computer ?

Thank you for trying. Please state exactly what you think is the difference between thermodynamic entropy and Shannon (or Hartley) entropy and what exactly you think the Second Law says about both of them.

Well I'm sorry if all you want to do is make unqualified generalistic pronouncements , one counter example is enough to disprove your claim. Mathematical theory requires that there be such a thing as 'the identity transformation' for any operation or transformation. Such a transformation require exactly zero energy since no change occurs. However I would much rather you entered a proper discussion like other members here and addressed some of the points, posted for your benefit. You have made no visible attempt to answer the question posed in the opening post or thread title or to discuss entropy.

Quite so. In fact it is a member of many sets, for example the integers, the rationals, the set of all even numbers, the set of all squares of numbers.................. It is also the 'additive inverse' in set theory axioms for instance in peano's axioms of arithmetic. But I was giving the OP the benefit of the doubt as they say, as to what he was really trying to say, rather than just telling him he was wrong. Especially not to offer incorrect information.

How do you expect me to clarify it and why do you think I said ? I also copied a short quote to explain why I wondered if the OP meant imaginary when he said virtual. I will repeat that quote in case you did not read it. Look for the phrase 'unusual terminology'.

If you don't know 'whatever it means', how can you declare that zero is not a virtual number ? Zero is, in fact, a valid and necessary member of the set of imaginary numbers, which may be what the OP means. I have already asked for clarification I also note there are some other inconsistencies in the rest of your post that need addressing.

Kirchhoff (with two h's and two f's) was a 'polymath', who also contributed to Chemistry, particularly in the domain of chemical thermodynamics. And yes there is such a law, though it was not due to K but a gentleman named Hess. Hesse's Law and Hess Cycles. https://en.wikipedia.org/wiki/Hess's_law +1 for interesting developments of your musings. I have also mentioned them in my thread on entropy and information.

No it isn't. This is where my RAM example comes in. The information may be set but unavailable, which has the same effect as being reset. This would be an example of the Caratheodory version of the second law. "In any system, there are nearby local states that are unavailable to the system" A computation that involves no energy is the topological transformation of a square to a circle. The information is available whether the actual transformation is performed or not and whether the necessary topological theory has ever been conceived, let alone enacted. You have now also mentioned this idea Thank you for spelling all that out in detail +1 My apologies, I didn't lin to the originating thread. https://www.scienceforums.net/topic/126656-experiments-and-information/?tab=comments#comment-1200346

I like the first part. But this part runs into the difficulty I mentioned with the RAM chip. Notably the different erasure methods. For instance I can simply switch off the power to that chip. Or I can cut one or more address lines making the given cell unavailable. Or I can perform the more conventional activation of the appropriate address lines and then overwrite a zero into the given cell. I am sure there are more options.

Yes this is a damped oscillation, as you say, but there is more going on that. I'm not sure what part of my post you were responding to though.