exchemist

Now you seem to be confusing dark matter with datk energy. Which of the two do you want to discuss? Or do we need to explain to you the difference between the two?

I told you: in galaxies. The problem is what it consists of, not where it is.

That's intriguing. I suppose that strictly speaking radiation energy is not heat energy. So I don't think (though someone may correct me) that one has to treat energy conversion to electricity by the antenna as a heat engine.

Yes I can see the logic of that, especially for someone with what sounds like a rather ghastly experience of religion in youth (I was more fortunate). I am merely pointing out it is not a distinction you can necessarily expect others, in other English speaking countries, to understand automatically by these terms. Faith is not a pejorative word over here. Its connotations are generally neutral to positive. "Blind faith" would be pejorative, however, and I think that is what you are describing, actually.

I can't immediately see what this reply of yours has to do with the question you asked or the answer I gave you. But let me see if I can help dispel any misunderstandings. Light, or other EM radiation, is not energy. EM radiation has energy. Not is, has. Energy is one of the properties of EM radiation. It also has other properties, such as velocity, amplitude, wavelength, frequency, direction, and (somewhat counterintuitively) angular momentum or "spin". Energy is merely one of these properties. The time dimension is obviously important to describing any wave. This is not specially profound, I think.

OK but you are talking about one (particularly crude) view of religious faith. The term is broader than that, at least on this side of the Atlantic, in speech and in the written word. One may speak of faith in an institution, or in a person, or in predictions, e.g.of the Met Office or a financial adviser. Admittedly such usages may be intended to draw a parallel with religious faith, but in a positive sense, whereas the sense of belief at variance with evidence would obviously have a negative connotation. But maybe in view of this exchange I should be careful not to use the term in discourse with Americans.

Interesting. My OED says, for meaning (1), "Confidence, reliance, trust (in the ability, goodness etc of a person ; in the efficacy or worth of a thing; or in the truth of a statement or doctrine). It does go on to say "in early use, only with reference to religious subjects; this is still the prevalent application and often colours the wider use". So not exclusively to be used in religious contexts, though it often is. There is nothing at all, in any of the meanings, to suggest that belief despite evidence to the contrary is in any way intrinsic to the meaning of the word. (In fact, its use in everyday speech makes it obvious that cannot be the case.) So I think you have made that bit up. 😄

What we call cornflour, then?

Maybe you are right, I was a bit thrown by the enumeration of the ingredients in the soy sauce. I don’t know what modified maize starch is for - a thickener perhaps? - nor what function yeast extract paste serves. But aside from these and some of the soy sauce components, the other ingredients seem broadly recognisable.

Not sure I agree. We have faith in the theories of science, after all. These theories are not facts but provisional models, yet we trust them - or many of the better established ones at least. That is faith, surely? But different from religious faith, certainly.

You can't just recycle it, because of "entropy", but you may be able to get some further use out of it, depending on the circumstances. The basic problem is that heat energy is the kinetic energy of random motion of atoms and molecules. It is thus in a sense "disordered" and cannot be completely re-ordered again. All non-reversible processes lead to an increase in entropy, which means (loosely speaking) a dispersion of energy in a way that cannot be completely recovered. However waste heat from many processes can be put to further use. For example waste heat from power stations can heat homes, commercial greenhouses, or swimming pools. And heat pumps can raise the temperature of heat energy from ambient air or the ground to something useful for home heating, although some extra energy has to be put in to do that. High temperature heat energy has lower entropy than low temperature heat energy, so the higher the temperature the more uses it can be put to. Machines like car engines and power station turbines are "heat engines", which rely on converting high temperature heat energy into mechanical work. However, due to the disordered nature of heat energy, they can't convert 100% of it, so there is always waste heat rejected from any heat engine, usually more than half of it in fact. I've tried to explain this in simple words, but really you need to read about the second law of thermodynamics and a bit about the concept of entropy, to see what the limitations are.

No. “Pure” energy is Star Trek, not physics. Energy is a property of a physical system. You can’t have “pure” energy any more than you can have “pure” velocity. It’s a meaningless idea.

Yes fair enough I was thinking more about the colours than the temperatures. A roaring Bunsen flame is also blue but nowhere near as hot as oxyacetylene.

The yellow flame is what you get without premixing of air and gas. This gives less efficient combustion, as shown by the yellow colour which is due, if I recall correctly, to incandescent unburnt carbon particles, formed by thermal cracking of the hydrocarbon fuel before it has a chance to burn. These flames have to burn from the outside in, as air reaches progressively further into the gas stream. My understanding is that the blue colour in the (far hotter) premixed flame is not just due to black body emission but to chemiluminescence of some of the species generated during combustion, which are formed in excited states and emit light as they drop down to the ground state. There is a reference to CH. and OH. radicals, which do this, here: https://ncbi.nlm.nih.gov/pmc/articles/PMC7345390/ But flames are very complex systems, chemically speaking, involving branched chain radical reactions in which a large range of molecular fragments take part.

No, it was to me. You must be confusing it with a different idiotic response.

If you buy these industrial concoctions you are asking for it. Why use 5 ingredients when 25 will do, eh? Worse than a Yotam Ottolenghi recipe.😄 But I don't know what ingredients cause bloating in susceptible individuals. That's more of a medical than a chemistry question, it seems to me. Someone else here may be able to help.

What has your idiotic response got to do with my reply to your question?

Not true. We know dark matter is in galaxies, because it is the deviation in their rotation rates from what would be expected from the masses of the bright matter they contain (which we can estimate)that leads us to infer there is extra "dark" matter present.

Science aims to provide predictive models of nature. Truth is a notoriously tendentious word to use in connection with scientific theories. It has been said, rightly in my view, that in science all truth is provisional. In chemistry, for instance, it is not uncommon to have more than one model for the same thing, with both acknowledged to be only approximations. One chooses the model appropriate to the task at hand and it would be considered very naïve to call either of them "truth". Theories in science justify themselves by how well they model and thus predict what we observe in nature. If two given theories are not fully mutually compatible, that does not indicate a flaw in logic. It merely reflects the possibilities that either we do not have the relevant observations of nature to resolve the contradiction, or that the problem is too complex to model exactly. (Physics is unable to model exactly any chemical system more complex than the hydrogen molecule ion H₂⁺.) You may consider this response is such that you do not wish to discuss further with me, but if so I may draw conclusions about what tool is having trouble justifying itself. 😆

It won’t work. Firstly, thermal energy is divided between different degrees of freedom, only some of which are vibrations, the others being translations and rotations. Secondly, where vibrations are involved, different substances have different characteristic frequencies of vibration. Temperature, on the other hand, is proportional to the total thermal kinetic energy of an object, regardless of what substance it consists of, or what physical state it is in.

You fail to understand what science does, it seems. It is not an abstract exercise in logic. It applies logic, sure, but it does so, crucially, to observations of nature. If those observations cannot all be reconciled by the application of existing theories, developed logically as they are, that suggests - logically - there must be missing observations that might resolve the contradiction. That is quite a normal state of affairs in science, because it is an unfinished enterprise of discovery. It does not follow there is a defect in logic, just that there is missing data for logic to be applied to.

There is no difference between the two, really. Potential is just the integral of a force over a distance. Atoms are inanimate either way.

You will need to explain why the two options are different. To me they look the same.

You have not taken in what we have been explaining to you, apparently. Classically, nothing can escape, that was the original conception of the black hole and is still strictly true of them. Later however, Hawking applied QFT to it and showed that the region at the rim, but just outside, would be caused to radiate by the intensity of the gravitational effect it creates. There is no inconsistency here and no "mistake" to be admitted. Nothing that enters can leave. That remains the case. But radiation just outside can certainly do so and this may make them look less "black" to an observer than in the original, non-QFT, conception of them. Do you understand?

No, just intrigued by @TheVat's remarks about solanum and BPH. It was he that introduced the subject, which happens to have salience for me right now.