studiot

It would be a good idea for you to find out what is meant by the words you are using before embarking on this quest. Do you know what is perpetual motion, becuase perpetual motion itself is not only not forbidden by the Laws of Physics, it is required in appropriate circumstances. (Newton's First Law). However constructing a P.M. machine, even in theory, is an entirely different ball game. Do you know what a machine is? Originally it was a device for "putting work into a convenient form" - It does not change the amount of work required. With the discovery of further forms of energy it came to mean a device for transforming energy from one form into another. Formally this became the Science of Thermodynamics and from this it was realised first that "You can't get something for nothing" which lead to the idea ( and prohibition of) a Perpertual Motion Machine of the First Kind, which is a device that does exactly that. It produces energy with no input. Further development lead to proposals for more sophisticated machines that did not create something from nothing, but did output useful work directly from heat energy. These were called a P.M. Machine of the Second Kind. This was then discovered to be also impossible and a heirarchy of forms of energy was established to explain why.

You might find this book of interest. https://www.amazon.com/Thermodynamics-Earth-Planets-Alberto-Pati-f1o/dp/0521896215 It should be accessible to anyone with high school maths and explains things as it goes along.

I suppose it's about whether the mathematical concepts which are used have a physical meaning or not. When you proof a mathematical concept with a physical meaning then proof in math and science are the same thing. You have the density matrices, metrics... Perhaps you could explain to me how this is an answer to either my question directly to yourself or to the original post? Either the 'proof' is the same in Mathematics and Physics or it is not. You seemed to me to be asserting that it is the same so I asked for confirmation since My OP operates from the premise that it is not the same and furthermore I offered one example of difference. I do not claim it is the only example.

So you were just guessing.

Where do you know this from? Is your position that there is no difference between 'proof' in Mathematics and 'proof' in Science? The example I gave arises because Mathematics is built on axioms and propositions, proof is a process of verification of the consistency of any proposition with what precedes it in the structure. Scientists do not have this absolute luxury since there may be a scientific phenomenon beyond their knowledge that negates their prediction. As a result of this scientific 'proof' is really about the verification of a prediction.

I don't think you can generalise about the subject at all, some are good, some are bad. Though I do think CharonY has nailed the basis of a good popsci book. Authors are like the general population at large. A percentage have a good grounding in Science, others offer second hand knowledge from what they ahve been told, yet others just bullshit along. Whatever their background some naturally want to tell a story ( the narrative of CharonY) and these provide many examples of superbly interesting and entertaining tests. Others just churn the handle, and it shows. Very often the publisher relies on heavy promotion to boost this brand of author so these are unfortunately the ones in the public eye. Most of us will have a main area of expertise, and may then welcome something a bit lighter in scientific areas that are peripheral to us individually. I know I do. Geology is such a subject for me and I find that unless I am actually working to BS CP 2001 (Site Investigations) the dry pedantry of the geological language tiresome. But I also like to be able to trust the author and I find that popularising books by recognised professors such as Mike Benton can bring the subject alive. But it is also true for fiction that Jane Austen leaves me cold but i have read and reread C S Forrester books many times. Yet others find that Austen was a great author. So, I imagine, it also goes with popsci. Others will have a different opinion

Mark, Since discussion of fields is both offtopic here but of great general interest I have started a new thread for you to ask field qustions.

In any feedback control system the sensor should be as close as possible to the business end of the device. Having the sensor up by the fan is counterproductive as it will respond to changes close to the fan before these have any effect on the boring machine end. So any desired change in airflow at the boring machine end will effectively be short circuited. You said your tubes were a couple of kilometres long so the latency in the control system will need to be designed to prevent this happening. 3MW is a big fan.

Yes, the dehumidifier is a scaled down version of the industrial plant I mentioned. True, the device has apparently to be different from that which someone else has already made.

No I did not miss the sometimes. But since you made a statement, conditional on the sometimes, I asked about the times when that holds true. Since I offered two mutually exclusive possibilities (the third not said being a combination) the reply "In no way" is puzzling to say the least. I am sorry we are havng such trouble communicating, but I certainly can't agree that discoveries deal with the known. Surely that is a self contridiction? How is something a discovery if it is already known? I stand by my scenarios, perhaps some examples might help? 1 )Van Leeuwenhoek discovered something no man had ever seen or had any idea existed. He named these things 'animalcules'. He was the first man to see microscopic organisms. 2) Galileo dropped two cannon balls from the tower of Pisa to see which one would land first. A test between two different theories. I am sure I could find many many more examples.

But the air doesn't usually surround the surface. Water for instance does not condense on the top surface of the same polythene. Take a piece of plastic that nowhere near covers or tents a region of air and see just how far you have to cool it to creat condensation on either top or undersurface.. So however you cause the evaporation it is also important that the resulting higher humidity is not allowed to escape. And yes the 'desert still' (also effective in the open ocean) is the ultimate version of this. To go to forced cooling, you would be talking about desalination plant, which I don't think is the purpose here.

I long suspected this, but thank you for confirming your ability. Is it something to do with that contraption on your head?

Shouldn't this be in Homework Help if it's for a project? It's slightly more complicated than that, because the surrounding air is often very (very) dry so your apparatus would have to be very very cold to reach dewpoint. The purpose of the plastic tent is to evaporate some of the liquid water and concetrate it just under the tent. This greatly raises the humidity of the air just under the tent. So this tent does not have to be so cold, in fact you can often see condensation under polythene sheeting.

I should have said there was no visible action other than the box falling over. And there were no hidden jacks poking the box over the table was an ordinary classroom table. As far as I am aware, DE Bono never revealed the mechanism, which must have been inside the box.

Whilst I can see the need for a limited supply of certain types of gun in a country like the USA, I can't see the need for widespread availability of military automatic weapons. Proper control of these would be a very good start.

Hint do you need to oxidise or reduce the ferrous ion to ferric ?

Can't see any of us falling out over this so long as the new troll stays out of this thread. I described a situation in which I was deliberately tricking you by pretending to lug the ball. You can't do this in Mathematics 'proofs', only Science ones. There was also a hint in the De Bono reference and the thread title was taken from his book 'A Five Day Course in Thinking' https://www.google.co.uk/search?q=edward+de+bono&ie=utf-8&oe=utf-8&client=firefox-b&gfe_rd=cr&dcr=0&ei=w2HSWbDHEpyq4gTeq6xY One of De Bono's demonstrations went thus: In front of the lecturer was a table. On the table was a nearly cubical opaque box. (I can't remember if he brought it in or it was there at the start) The box was ignored by the lecturer, but partway through it toppled over onto its side on the table with a loud bang and just laid there. The lecturer continued to ignore the box until the end of the lecture when he said "You all saw what happened. Why did the box topple over?" One of his books goes through in excruciating detail the why mechanisms proposed by many famous physicists could not produce the observed action.

This is what I mean by thinking. +1 (This harps back to an Edward De Bono demonstration)

This thread was inspired by the recent long philosopy thread and by Edward De Bono. The discussion is about the difference between mathematical proof and scientific proof. One form of proof that is available in Mathematics but best avoided in Science is that of showing the negation of a proposition leads to a contradiction vis-a-vis some more basic statement. For example the proposition that gravity causes objects to fall to the ground is false. I struggle up a podium lugging a large ball. I stretch, holding the ball out and shout to an assistant standing below "Catch" I then drop the ball But instead of falling the ball shoots upwards. Therefore gravity is false.

In what way are you suggesting that this invalidates the synthesis process itself or the efforts of those who employ it correctly? I am not convinced by this statement. Accidental discoveries for instance. Or tests between opposing hypothesis.

Since no one else want to answer this here goes. When the piston initially starts to move it will generate a pressure pulse immediately in front of it. This pulse will move away from the piston at the speed of sound in the gas and eventually expel a pulse of air at the open end. If the piston continues to move smoothly and evenly it will generate a succession of such pulses which will coalesce into a region of increased pressure air between the travelling initial pulse and the piston face. So once the air has commenced exiting the open end the pressure between the piston and the open end will be increased all the way but will not rise further. Waves or pulses will only be generated if the piston moves jerkily. Edit As a matter of interest you cannot apply Bernoulli's theorem directly here as there is an energy input to the fluid. The setup is effectively the inside of a pump.

Not sure if that was a response to my post, but it was not what I meant.

This doesn't preclude the possibility of 'flat spots' in systems with gravity as I already noted.

Thanks for that excellent list, dubbelosix. +1 You are now officially dubbeloseven

I haven't been following this thread, but thought I'd take a look and, after all that analysis, this last line caught my fancy. The opposite of analysis is synthesis, rather than creation which is different again. So many terms and a full study process will probably involve all three these days. Deployment of synthesis and or creation is more difficult than analysis in my experience.