studiot

It was asserted (not by me) that dimensions are part of Mathematics. I am suggesting (and backing it up properly) that dimensions are what differentiates Mathematics from other Sciences. (This is not the place to argue whether Maths is a science or not - I don't care) Dimensions are what give meaning (in the physical world) to mathematical statements such as 5 x 3 = 15. Mathematicians don't care if there are any objects or groups of objects with the properties '5' & '3' They just deduce that if there were then the result would be 15. Nor do they care what particular value a numerical constant used in other sciences such as gamma might have. But that value may matter vey much in the other science. All I am trying to do is hold an open discussion about these things without the other person starting with a closed mind and just automatically and unthinkingly rejecting everything.

Gentlemen, you are just repeating yourselves, without any supporting reasoning or evidence. If gamma had a value of 1 then the laws of Physics would be different, but 5 x 1.4 would still be 7,, which is the mathematics. Any first year mathematician will be exposed to countless analysis texts and lectures that stress the mathematics of 5 is extracting ( and dealing with the theory of) the 'fiveness' of 5 from the application. Conversely, any first year Physicist is likely to come across the solution to the wave equation which discards half the mathematics under the phrase we only want the real part of the solution. The imaginary part has no meaning. Science gives meaning to the mathematics

No, that is the difference between Mathematics and other Sciences (if you conssider Mathematics a Science). Mathematics deals only with the numbers. (Note I did not say Mathematics only deals with numbers and nothing else - that is a different proposition that is not true)

So you agree that not all equations used scientifically are 'consistent' (dimensionally I presume you mean) ? Talking of facts, In fact most of the reactions here have assumed that Physicists have taken a perfectly good Mathematical process and usurped it for purposes of their own, declaring a sort of UDI that they and they alone have the right to decide how equations are used. Equations are of Mathematics, not of Physics ( though I grant they are vey very useful). In Mathematics 5 x 3 = 3 x 5 = 15 period. But in Physics, 5 metes times 3 metres make 15 square metre which are not the same as 5 Newtons times 3 metres for instance. Mathematics does not distinguish. The chemical equation you declined to offer has a combination of units of concentration and units of mass. The solubility constant is dimensionaly consistent in any one equation (including the one required here), but its units differs from reaction to reaction.

I think that John Cuthber's posts show that he is well aware that Chemists have a more relaxed attitude towards dimensions, than Physicists. eg Acid + Base = Salt + Water. Perhaps you could tell me the dimensions of the solubility products, Ksp for silver chloride and lead chloride respectively and explain why they are different? Then perhaps you could look at this chemistry problem that is posted on some other science websites at this moment. What reaction equation would you propose?

And I thought that was the limit of Spielberg's dinobudget. Another childhood illusion shattered.

Hello, youcef and welcome to ScienceForums. It is refreshing to see someone wanting to discuss Science so I will offer a suggestion. Check the rules of the SF speculations forums and amend you post before some moderator locks it. You need a focal point for discussion, usually in the form of a question. PM a mod and ask if you are not sure. As to your video, yes light based data processing is attractive because it is inherently inertia free so can go faster. A minus point is that at some juncture you have to interface with the physical world to get your device to do something. I am suprised you vid does not mention phototransistors.

frank, Yes all systems are a balance of compromises. I think a 50m borehole would cost more than a small car in Somerset. And it would go below local river level, which would involve issues from the river /water authority. Thank you for the link. Interesting. There are other ways to add in a solar boost. Modern heat stores have additional internal coils for any available preheat source. This is the cheapest method.

Not as well as the salesman promised, but perhaps as well as the engineer expected. You can see the end of last week's snow melting away around the base.

Hey Studiot, What sort of ground source do you use? Was it expensive? I really don't know how to answer this, but I am happy to discuss the capital cost which was higher for the hatpump ( ) than for a replacement gas boiler. Ground source would have been in some ways better in some ways but I worked out that I would need 100 metres of buried pipe and there is not easily enough room in my back garden for that. The picture empahsises the point about insulation, the black insulated pipes on the wall convey the ouput hot water from the heatpump to indoor heatstores.

Well it looks like you and I are the only ones interested in mundane things like heat pumps, rather than unattainable nonsense at the supposed end (or beginning) of the universe. So is 40C enough? It really depends on what you want to achieve. You can't start with the heat pump ideal chart, you need to define objectives first. Air to air pumps have a higher operating COP than air to water because they may operate at a lower Th. However I use mine to also supply DHP (domestic hot water) and 40C would be nowhere near hot enough. The salesman claimed my pump has a COP of "over 4"", but he won't provide figures for what the outside temperature is. There is another thing about air source - the air humidity plays a large role in performance and high humidity (as we have) can reduce COP of the pump. But overall the system is producing cost savings compared to the gas boiler it replaced.

Was that truly your response to my post and offer? Did you not even want to correct my spelling mistakes in the last line?

Would you rather believe the salesman's exaggerated claims or those of a proper engineer? The truth is the advertisers play fast and loose with the temperatures Th and Tc. Tc is indeed the mean outside air temperature where the pump is located. But Th is not the room temperature. Th is the temperature for the heat pump fluid, within the heat pump itself. So the efficiencies you are being shown is just for the heat pump are are indeed true theoretical maxima. But it takes more than a heat pump to heat a room. It takes a complete heating system. This means that there is a heat exchanger of some sort within the room which has to be above room temperature to supply heat. The greater the heat demand of the room the greater the required temperature difference, above room temperature. In turn this heat exhanger is heated by the heat pump fluid which has to be at a yet higher temperature. Then that fluid has to be piped from the heat exchanger itself to the heat exchanger and no insulation is perfect. So the fluid leaving the heat pump has to be at a yet higher temperature still to arrive at the heat exchanger at the correct temperature. So the Th produced by the heat pump has to be higher than the room temperature by three increments, each of which has to be carefully controlled to minimise inefficiency. Bottom line the efficiency of the heat pump is not the efficiency of the heating system. Having said all that I installed an air to water hat pump heating system in 2016 and am happy to discuss it performance with anyone who has a genuin interest.

Heating the room air to 20C alone will not raise the room temperature to 20C as a whole. Look carefully at the link you quoted and their example refers to heat supplied to room, not air temperature. There are pros and cons to both air to air and air to water heat pump systems.

First off, interestingly instead of the usual quote this popup I got "Ask Cortana about the 100% true the U.S............." I only got to quote this after I blew that off. Effing computer programmers and American companies. Anyway I largely agree with what you said but point out that "past figures are no indicator of future performance in business" Why can't we call a spade a spade and say cheaper not cost effective? As a matter of interest I was told many years ago and I watched this effect in my working life that there are fashion cycles in building g alternating between steel and reinforced concrete fabrication depending upon two factors. 1) yes "cost effectiveness" 2) The relative ascendancy of training (advertising) programs for the two materials. This latter has had a big effect.

I'm not sure about modern China, but I think the USA is still the only country in the world that, if it chose to close the doors and pull up the drawbridge, could obtain everything it needs within its own borders.

You are mixing up quantum mechanics and relativity. Length contraction is a relativity phenomenon and energy is not a relativistic invariant.

Yeah, there do seem to be a lot about at the moment.

Talking of Doppler, I wonder, are your tomatoes subject the the red shift?

Hopefully somewhere indoors in this weather.

Parts per Million is weight for weight measure. So 200 ppm hydrogen means weight of hydrogen/total weight = 200/1000000.

The title says it all

Vortices are interesting for several reasons 1) Because they are not waves. 2) Because they can behave as though they were a substantial object, for example the whirlpools in a stream deflect the flow, but retain the identity and can even move about as an 'object'. 3) Because they have interesting properties in a field.

Good, now we are following the rules I can say Vortices huh? Reminds me of Maxwell. Thanks to the following websites https://www.pprime.fr/sites/default/files/pictures/pages-individuelles/D2/germain/Cargese2004.pdf This theory was said to be the precursor of modern gauge theory. http://www.physics.umd.edu/grt/taj/675e/OriginsofMaxwellandGauge.pdf

At last a proper thread about proper Science. Thank you Simbabones, +1 Here an opposition view on the demise of the Dinosaurs and how their subsequent fossils came to be where they are.