studiot

Just like back home in good old Blighty.

Most traditional textbooks split upon the lines I have outlined. They often go through a long list of chemical substances and their properties. Although very systematic and thorough this can be rather boring for many. However If you were in the aviation industry you can probably cope with high school maths so this book might be an appropriate overview Feel free to ask about anything you read that needs amplification or explanation.

Would these be the same folks who can't 'see' climate change ? 😀 Yay +1

Yes welcome, here is some starter information that may be useful. Originally Chemistry was divided into two categories Organic Chemistry and Inorganic Chemistry. The word organic meant that the 'chemicals' ( correct word substances ) derived from living things. Everything else was not organic or inorganic. We now know that this distinction is not accurate but these two categories still remain although organic chemistry has been revised to the chemistry of carbon and its compounds. So basically Chemistry is about all the varous types of substances and the interactions between both themselves and non material things such as light and magnetic fields. Since those early days important sub classifications have been made such as Analytical Chemistry the Science of determining exactly which substances there are in a smaple and how much of each. Physical Chemistry The Science of the physical properties of substances such as density, colour, melting point, boiling point, refractive index, solubility etc Structural Chemistry The study of the internal structure of each and every substance Reachion Chemistry the study of rates and mechanisms if chemical reactions. All of these apply to both Organic and Inorganic Chemistry. Yet more subcategories apply to more specific areas such as biochemistry, mineralogy, crystal chemistry, rheology, molecular chemistry etc.

Firstly you seem to me to be describing curvature here and in previous posts in this thread using too few dimensions. When you get to space or spacetime there is no such thing as 'opposite curvaure' . Secondly you might like to review a simpler system, that of the difference between moment of inertia and product of inertia and the inertia tensor. This offers a simpler explanation as to why the are many solutions a given moment of inertia, but the product is unique.

Hi Jane and welcome. This is presumably a project ? I suggest you haven't given us enough information. You should sit down with your tutor and draft a detailed specification of what you want to this arm to do. Lift - how much ? Transport how far ? environmental conditons of working - temp range -humidity - hazardous atmousphere ? and so on. Having a target objective is the way to a splendid project.

Here is the rating plate on my heat pump. Note it is not the window or protable variety. The cooling mode has about 10% less capacity than the heating mode.

One point I keep making that only swansont seems to appreciate concerns 'precursors'. Most replies seem to assume there is only one 'precursor', which is of course, impossible for building more complex molecules. But not only do we need at least two precursors and reactions, all the evidence suggests that we need a whole chain of them. The important point is that we do not know the length or composition of that chain. These fact pose immense difficulties in estimating overall probabilities and Ken's efforts are far too simplistic. For instance the reaction that produces precursor A may occur in one galaxy and the reaction that produces precursor B may occur in another or at a time beyond the lifetime of the A molecule. And the new AB molecule must have a lifetime long enough to participate in the next reaction for the next stage. The treatment of the volume over which the concentration is calculated is important. So selecting nice concentrations and reactions rates is unviable. If I were asked to suggest a calculation scheme I would suggest assigning partial probabilities to each stage of a probability tree and considering the consequences of 1, 2, 3, 4 ....n stages. This approach is taken in engineering Limit State Analysis and Design and that is complicated enough; the reaction pathway to life almost certainly has many more stages.

If you are going to put it or them into a card then you need to increase the turns not by the usual linear lineup of one alongside the other but in a flat spiral fashion. In order to mechanically couple this to the effort use a mechanical membrane, rather than a central push rod.

Glad you are back and had the time to compose that excellent explanatory post. +1

Ken I am not getting at you, indeed some of my comments were directed at this statement from CharonY I call your and everyone elses' attention to the following paper, desccribed by Prof Benton as "One of the msot daring papers ever published .... yet one of the msot influential papers of the 20th century" Extra Terrestrial Cause for the Cretaceous - Tertiary Extinction. Nature 6th June 1980 Alvarez , Alvarez, Asaro and Michel. It introduced the famous iridium spike and a formula for the geological effects of meteorite impact. My point is that we just do not have enough information to calculate probabilities so readily. Which is why I offered something we can calculate and swansont kindly amplified. As regards meteor impact there exist very serious barriers to the idea that these relatively delicate 'precursors' arrived by meteorite. Do you have a recipe book by the way ? Meteorites are known to have enough energy to melt and even boil rocks, by the impact, so what would impact do to precursors ?

Ken you also need to consider temperature. At the temp of space (say 3o) or at the more comfortable temperature of an Earthlike planet (say 300o) or at the temperature of a hydrothermal vent (400o to 450o). The Arrhenius equation is very relevant here.

The point about equations is that it does not matter which way round you write them. If A = B then B = A Most of the laws of Physics are of this form so if Time is involved it does not matter whether time goes forward or backwards, the equations still hold. There is one major law of Physics called the second law of thermodynamics which doe not have the form of an equality (or equation), it is an inequality so If A < B then going the other way B is greater than A. Since the second law involves time it cannot be reversed and hold the same form like an equation.

You were very clear, but just plain wrong. It is very far from clear to me. You are just not understanding what you are being told, perhaps that is why you have not responded to my previous post. Let us take a much simpler example of chemical kinetics that we can calculate. The chemical reaction between two of the commonest molecules in the universe. Consider a cluster of hydrogen gas. We can calculate the minimum size required for this to ignite as a fusion reaction, forming a star, or the for the time we would have to wait to expect such an ignition to happen. But we do not have the necessary information to do this the the many times more complicated series of reaction that are necessary for life to occur.

I understand from this claim that you did not actually understand my explanation at all or you would not have said Because in a laboratory you would have control over the concentrations. What I also meant was we do not know what concentrations to control. That follows directly from my description of chemical kinetics.

Do you really think this is a sensible question ? We do not have a recipe book for life of any description. So let us say I show you a large opaque black bottle and say this black bottle has grains of sand in it. How many grains doe it contain ? You may not examine the bottle or know how big the sand grains are. That is a far far easier task.

OK so Chem K is based upon the idea of estimating the chances of two molecules, say A and B meeting to create the reaction. That is called a simple reaction. In general, The greater chance the faster the reaction. The chances increase with concentration of the molecules A and B. They decrease with the requirement that three (or more) molecules need to meet to further the reaction. Now, as @genady says, at astronomical volumes the concentrations are minute (concentration being the number of reacting molecules in a given volume) There is a further complication. That is that many, if not most, reactions are actually what is called multistep, not simple. Each step has to occur in the correct order within the correct timescale (ie before something else happens to the reactants) for the final products to emerge. Now remembering that all probabilities are less than 1 and that these probabilities are multiplied together you should be able to see that this will result in a very very small number of successful reactions. The trick, of course, is estimating these probabilities.

The classification depends upon where, and in which country, you look as well as the date of the classification scheme. All very confused. I think the sulphur comes from pyrites. https://www.nicholaswylde.com/content/lapis-lazuli/ This discussion below is interesting. https://www.mindat.org/mesg-326838.html Meanwhile here is some scanned material that I promised. First, Wells Then here is some well presented wider information from Latimer and Hildebrand Reference Book of Inorganic Chemistry

What do you know about chemical kinetics ? The answer lies therein.

I see that vague questions receive vague answers - suprise suprise. I a I also see that specific answers to very specific questions do not even receive acknowledgement.

Interesting subject +1 It is important to distinguish between the gemstone lapis lazuli, lazulite and lazurite minerals, all of which are blue stones. https://minds.wisconsin.edu/bitstream/handle/1793/11597/Lazulite.pdf?sequence=1&isAllowed=y Since my return I have also dug out my 3rd ed of Wells (1962) which has some things to say about this. I cannot trace a later edition. I willpost what he has to say when i can.

Much of the knowledge of today came directly from the stimulation of the economies I referred to.

That's really good news. I think we can build on this mechanical experience. I have been busy these last week but I see other members have been looking after you. I would, however like to bring your feet fimly back to ground to feel the gravity. I think you could benefit from this book. It is one of a kind where the author tries to use physics to explain well known mathematics, rather than the other way round. So rather than dry mathematical general theorems about polygons try the polygon of least area (p35) The Mathematical Mechanic : Mark Levi : Princeton University Press. But remember to keep asking questions as you will find much unfamiliar as well as some familiar stuff.

Tomography is a highly mathematical subject that takes a great deal of postgraduate level understanding.