exchemist

OK I see Project Green Challenge is a real thing for schools and colleges, so I won't accuse you of spamming the forum. A couple of comments: - You need to get rid of the greengrocer's apostrophe in the first line, as it makes the ad look like the work of crank. "Its" does not have an apostrophe. ("It's" is short for "it is".) - The suggestion that glyphosate is a danger to human health is questionable at best. See this assessment by the European Food Safety Authority (EFSA) in July of this year: https://www.efsa.europa.eu/en/news/glyphosate-no-critical-areas-concern-data-gaps-identified. Furthermore the WHO clarified its 2015 assessment a year later, here: https://www.chemistryworld.com/news/who-clarifies-glyphosate-risks/1010208.article. So your poster, at least as currently written, looks to me like unjustified scare-mongering. This is important, as overblown claims by environmental activists will eventually damage their credibility. If you want to be listened to, you need to do your research and not exaggerate wildly. - You could perhaps consider a poster with a more positive message, stressing the benefits and ease of use of the natural options you mention. I think everyone understands that the less we spray artificial substances around the better, so domestic gardeners will be receptive to a message along those lines. But farmers can't mulch their way out of weed infestations, nor can they pull weeds out by hand.

Good question. They might, given that it is the kind of scientific cooperation that won't be that much of a hot button issue for the Brexitters in the country. By the same token it is unlikely that any future Conservative administration would be ideologically mad enough, or see enough political mileage in it, to reverse such a decision once it was embedded. So I don't see this being at much risk of becoming a political football. I suspect any decision to join would depend on what degree of financial contribution would be required. Given the appalling state of the country's finances, Reeves will be looking to save money on things that are not central to the economic and political strategy. I should have thought it ought to be cheaper to be a contributor to a collaborative project than to try to do it alone. Doing it alone is all part of the stubborn dickheadedness of the current government of fools.

Can’t help there. I pay little attention to that stuff.

Considering energy in analysing problems in physics is particularly simple and powerful, because it is a conserved property. Momentum likewise. It can often be useful to consider both. Depriving yourself of one of these is going to just make everything a lot harder.

I think there are categories determined by the number of posts one has made. It seems to be a feature of the forum software. A bit childish in my view, but nobody pays any attention to it so it doesn't actually matter.

Probably. It's the now usual Brexitty Little Englandism to insist on trying to do it on our own instead of with the EU. What will happen is the budget will be too small, not much progress will be made, and then in a few years someone in government will pull the plug.

OK that’s interesting - in a Michael Caine “Not many people know that” way.

But that might be Aussies having a laugh at the expense of visitors. Like the famous Drop Bears.

This has all been gone over, at length, elsewhere, months ago. It is just being spammed.

Actually I was being stupid. The more basic point is that whatever water is used to make hydrogen is converted, when the hydrogen is oxidised in a fuel cell, to…….water! So it just becomes part of the water cycle, between atmospheric water vapour, rain and the oceans.

Just think, for a minute, about the volume of water in the oceans.

Oh God, not this rubbish again: http://www.sciforums.com/threads/man-suffocates-to-death-in-his-sleep-because-his-nose-was-blocked.166127/page-2#post-3718554 This story, from 30 years ago, concerns an idiot suffering from sleep apnoea, in which the throat collapses due to lack of muscle tension. He decided it would be a smart idea to stop the snoring due to his apnoea by shoving a tampon up each nostril, getting drunk and then taking sleeping pills. Unsurprisingly, the combined effect of sleeping pills and a large amount of alcohol made it impossible for him to wake up when his throat collapsed. This is what the coroner found, not anything to do with breathing through the nose, which is made up by this poster, who seems to have an obsession about it for some reason. This story resembles other daft stories circulated in the past, including several about spontaneous combustion and (my favourite) a story from the 1920s about a man allegedly strangled by his own thymus gland.

The formula of "zinc citrate" seems to be as given here: https://pubchem.ncbi.nlm.nih.gov/compound/ZINC-citrate According to this, it is actually trizinc dicitrate, with a molar mass of 574. This version does not appear to be hydrated. If a "dihydrate" has 2 extra molecules of water per formula unit, that would bring the molar mass to 610. So then indeed, for every 100mg of compound you would get 100 x 195/610 ~ 30 mg Zn. Not being a pharmacist I don't know what a "referenced intake" is, I'm afraid. It is certainly the case that pills contain a lot of other stuff besides the active ingredient. The size of the pill won't be a good guide to how much active ingredient in present. But in all cases the amount should be written on the packaging anyway.

This guy was in Rouen and I live in London.

You have struck a nerve. Notaries are the devil. The trouble I had with French notaires, when my wife died, was unbelievable. The problem is twofold. First they are not only acting for you as their client, but also in an official capacity for the government - which gives them a licence to treat you as a supplicant and dick you about. Secondly, at least in France, the number of them less than what is needed to provide an efficient service: it's one of those professions restricted artificially by the qualification process, creating an endemic shortage of notaires. This enables the profession to become a kind of "brotherhood" that can act as a cartel, pushing up fees, increasing the time it takes to get the simplest thing done or even providing basic customer service such as answering emails. I had to give up with one and employed another via a bilingual firm of solicitors in the UK that specialises in French inheritance and property law. So I left it to them to chase the blighter up all the time. It cost me a bomb and delayed everything by 2 years. And my brother-in-law also had to sack the one dealing with his mother's "succession" (=estate) when she died, because he was incompetent and dilatory. And the one he got in exchange was not great, either. Dealing with English solicitors is a breeze by comparison. We also have notaries, but luckily their role is far more restricted, just confined to witnessing and stamping certain kinds of official document. By the way, curiously, English "notaries public", as they are called, are bizarrely run by the Church of England! Amazingly antiquated.

What is depicted in that drawing is not waves but a static field or potential.

Questions are fine. Nobody says don't ask questions, least of all Feynman. What he is saying is just don't expect nature to behave like classical mechanics, or to be easy to comprehend. Feynman's joke about going "somewhere else, where the rules are simpler, more aesthetically pleasing, more psychologically easy" (my emphasis) contains an important point. Nobody who has studied QM finds it easy to picture. The maths works, but the physical picture it conjures up is murky. At some level one has to accept that struggling to make a consistent physical picture of what is going on is not really possible. Anyway, to your original question, these entities are fuzzy so trying to apply classical electrostatics, when you can't define the distance of separation, is bound to have limitations.

Erm, this poster seems to be selling fake driving licence ID:

No, it would not follow they have structure. It just means they are fuzzy round the edges, like any quantum entity (uncertainty principle, again). There is no defined "size", just a matter of decreasing probability of interaction, the further from the classical path you get. (Look up "cross section"). The idea of these entities being pointlike particles with "an associated wave" is unhelpful. They are what they are and exhibit both wavelike and pointlike attributes according to circumstances. You need to think in terms of probabilities, not classical exact values. (For some purposes it can be easier to think of them as waves, which "collapse" to a point only when they interact - but that too can be misleading.) As Feynman said: "I'm naht gonna fake it, I'm naht gonna tell ya it's like a ball bearing on a spring, when it isn't."

Or bots. The list of “teaching staff” on the website has exclusively Spanish names. Probably someone has gone through the local phone book. Noteworthy too that the moment you click on anything you get a pop-up talking about money and offering a discount. That’s not what you see on any genuine university website.

OK in that case they must have enough extra energy to ionise positronium, then.

The contact number for this "university" is located in Tenerife, whereas its website implies it is in the United Kingdom. I think you may be pumping a scam.

Not at all. It leads us to think in terms of fields and waves. But another thing you need to bear in mind is that pair production in general does not lead to a pair that separates. They would be bound together by their mutual electrostatic attraction, cf. positronium: https://en.wikipedia.org/wiki/Positronium

You are not at liberty to decide for yourself that these entities behave as point particles during the interaction in question. If such an assumption leads to wrong outcomes then the assumption must be wrong, must it not? I am not a physicist but I know from quantum chemistry that the interaction between electrons in an atom and photons is not modelled in terms of point particles.

No. It is a quantum mechanical, wave particle entity, so it has some particle-like properties under some conditions and some wavelike properties under other conditions. You must know this, surely?