exchemist

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.

Thanks but I’ll stick with the consultant’s advice. There’s always a slightly irrational temptation to think one can do something to take control by means of diet, when it may be largely wishful thinking.. The cranberry business seems to be mainly a marketing stunt by the Canadian agricultural industry, so far as I can see. The UTI may just have been an unlucky one-off event. If I get more of them then further action may be appropriate. He may give me an MRI for the sake of good order, depending how my next PSA comes out. So we’ll see.

Hmm. I've recently been seeing a consultant urologist for BPH after I got a urinary infection (citrobacter) out of the blue a couple of months ago (one of @John Cuthber's "wee burns" but nasty enough to go to A&E on a Saturday night). The consultant has not said anything about diet, in spite of my asking. He has however given me a trial course of Tamsulosin hydrochloride, which opens things up quite a bit, though he says nothing he does will lesson the risk of future UTIs very much. I'm not sure I need this drug. Things are OK without. So I may stop. It's the UTI that I want to avoid getting again and I'm not getting much to reassure me on that front.

The groups which tend to be the most electron-withdrawing will make it easier for H+ to be released ( more stable anion). A carbonyl C=O can spend some time as C⁺-O⁻. So the CH2 between 2 carbonyls gets the effect from both sides, making it easier for one of the Hs to come off, leaving an enolate anion, cf. keto-enol tautomerism: https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Organic_Chemistry_(Morsch_et_al.)/22%3A_Carbonyl_Alpha-Substitution_Reactions/22.01%3A_Keto-Enol_Tautomerism. You can apply the same logic to A vs. F. If you have an exam coming, you must have some revision notes or lecture material on this kind of thing.

Wouldn’t the nightshade family (solanum) also include potatoes and tomatoes? And even aubergines?

My understanding is that Hawking radiation and its effects have yet to be observed. So while they are a mainstream theory, I’m not sure they have been claimed as facts. But in any event the two ideas are not incompatible if you understand them properly. Black hole is a term devised before QFT was applied to the phenomenon. So Hawking radiation phenomena can be taken to be a refinement of the earlier concept.

The CMBR could, conceivably, be due to something else. But nothing suggests itself and the observed uniformity of the CMBR is consistent with the big bang theory of expansion from a small, hot start, as evidenced by the expansion measurement itself. So the two observations complement one another and applying Ockham’s Razor, the big bang accounts for both so why look further? As for the maths, as I say, not being a cosmologist and not being trained in GR, I have to leave that to those that have done the calculation. Maybe someone else here will be able to help you with that.

Not sure about the maths but I presume the principle will be an extrapolation backward from the measured black body temperature of the radiation today, using the measured expansion rate, and seeing how much time is required for the wavelengths to shorten, i.e. for temperature to go up, as you "recompress" the universe, to the point that you get to a plasma. But I don't pretend to be a cosmologist.

It wasn't an explosion at a location within the universe. It was radiation that filled the whole universe as it expanded. Since it would have filled the whole universe initially and no process is envisaged that could confine it later to a limited region, the prediction of the theory is that it should come from everywhere. As it apparently does.

I'm not going to watch the video. (Actually it is against form rules to require readers to watch videos or follow links off-site in order to be able to discuss the topic.) Also videos take ages to communicate what can easily be put in a few lines of text. If you can summarise the key points the video makes it could be helpful. Meanwhile though, from looking it up on the web, I can see there does seem to be evidence that a proportion of the population in N America is somewhat deficient in Mg: https://link.springer.com/referenceworkentry/10.1007/978-3-319-40007-5_6-1 However this source says this generally does not seem to be severe enough to have significant health consequences. The UK NHS says you can get all the Mg you need from your diet: https://www.nhs.uk/conditions/vitamins-and-minerals/others/ Spinach, nuts (e.g.in some breakfast cereals) and wholemeal bread are suggested as sources. (I eat quite a bit of nuts and spinach, though I don't eat wholemeal bread very often.) I would very much doubt that Mg salts are absorbed through the skin. Threonic acid was new to me. It is a sugar acid, a metabolite of Vitamin C, apparently. So that at least is interesting. I am by nature a sceptic when it comes to supplements, especially when there may be a commercial interest in pumping their benefits. My view is you are best off eating a varied diet with plenty of fruit and veg, exercising and not boozing too much and not bothering with supplements. But I'll be interested in what more expert people on this forum may have to say about Mg threonate.

That article is an elaborate way of saying time travel is not possible. What does it mean to say you can "carve" spacetime? It's bullshit.

"Not particularly well absorbed" ≠ "not absorbed at all". You can draw your own conclusions.

Nobody claims it is, apart from Dr. Who. Can you provide a reference to show who thinks it possible?