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John Cuthber

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Everything posted by John Cuthber

  1. He pointed out that it's impractical. "Liquid hydrogen must be contained at incredibly high pressure or maintained at very low temperatures by complex cryogenic systems. " As far as I can tell, only space rockets use LH2 as a transport fuel- and even they sometimes shy away from it. I don't know of any serious project that is looking at LH2 as an energy storage medium . There are two reasons. 1 it's hard. 2 It's inefficient- you waste a lot of energy cooling and heating it. The thread is about an new trick in the process of making hydrogen; what you do with it after that is a separate issue. Incidentally, If you generate the gas electrolytically, the answer is "none". You don't need to do work compressing it; the reaction will still work at higher pressure but needs a slightly higher voltage. Hydrogen generators exist, so they are clearly "reasonable"
  2. Nobody said you did. But you did raise the equally irrelevant liquid hydrogen.
  3. Well... pretty much the same as a petrol tank. And there are plenty of 25 year old petrol fuelled vehicles on the road. They aren't all suddenly exploding, are they? At most, you need to add another line to the MOT test "leak test the tank". And LNG boils at about -162, and nobody is considering it as a transport fuel either. Why did you raise the issue? They never did. That's why we have regulations.
  4. Those were not incidents involving hydrogen. Hydrogen has one property which makes it rather more hazardous than natural gas- it has a very low ignition energy. On the other hand, the low molecular mass and comparatively low energy density (a litre of hydrogen carries less energy than a litre of methane) tend to reduce the risk. to exactly the same extent that it will leak through a badly made connection, it will also leak out of the area it is released into. There's a story of a demo where they emptied a tanker truck of liquid hydrogen onto the surface of a lake, waited 5 minutes and struck a match. They then invited anyone to do the same with petrol/ gasoline. Any fuel is, ipso facto, potentially dangerous. The way round that it to not let it escape. Not really. Once you tighten up the fittings so that the metal meets the metal, there's no hole. Practically speaking, Hydrogen won't diffuse through a mild steel pipe any more than propane will
  5. They typically use CuCl. Almost certainly not an organic dye. The tubes are typically coated on the inside- much like an ordinary fluorescent tube. That's a rather aggressive environment. These are more likely. https://en.wikipedia.org/wiki/Phosphor#Standard_phosphor_types though just painting a clear lacquer onto a white tube would work, as long as it was heat resistant enough.
  6. The emission spectra are changed slightly by a magnetic field. https://en.wikipedia.org/wiki/Zeeman_effect But the effect will be too small to see unless you have a tremendously strong magnetic field. The commonest use of copper chloride in this way is in fireworks. The colors of most modern fireworks involve a few metal chlorides, which fluoresce strongly in the visible wavelengths: Barium chloride produces green; strontium chloride produces red; and copper chloride produces blue. https://cen.acs.org/articles/95/i27/s-fireworks-produces-those-colorful.html But it's also used in lasers https://www.repairfaq.org/sam/laserccb.htm
  7. You don't seem to know what inbreeding is. That does not seem to be your only area of ignorance.
  8. They are the same as reindeer (note the spelling, btw). Caribou have been semi domesticated for a long time. Not sure there's much advantage over a horse.
  9. I love the advert for the stuff at the end of that page- particularly this bit "and it has a myriad of applications."
  10. I realise it's a year or so late but... That distinction is almost certainly meaningless. There isn't some magical cause and effect relation between an adverse event and depression. Some people become depressed after, for example, losing their job. But many don't. On the other hand, no matter what the chemistry in your brain might be doing, you will experience negative events in your life. So, if you are predisposed to depression, there will always be an event which might (on its own , or in combination with others) be the "causative event.". I think the reality is that the actual cause will be a combination of those two. But I have to say that it's only my opinion because I don't think it would be possible to find out. What test or experiment would you use to distinguish? How could you ensure that the chemical / neurological effect was there but no external cause ? How would you ensure that the external cause was there but without any chemical imbalance? At the risk of incurring Swansont's wrath by prolonging the inclusion of theism/atheism, that statement is factually incorrect. There are "plenty of" depressed atheists. (Obviously, there are far too many, but there are "plenty" to prove that Michael does not know what he is talking about) Sorry; I didn't think it should be allowed to stand uncorrected.
  11. To the enormous relief of everyone named "Faith", the same fate has befallen this
  12. I have seen an argument for a drop to 10,000 or so. https://en.wikipedia.org/wiki/Population_bottleneck#Humans but even that is controversial. However, at some stage in history, there were zero humans, there are now many. This implies that at some time in between, there must have been exactly one human. And that "species" survived so the minimum viable population is 1 (together with a phenomenal amount of luck).
  13. "NASA has calculated that the dam only slows the rotation by 0.06 microseconds" Watch me not care. The effects of harvesting wind power will be comparably small.
  14. Well, while we are talking about anecdotes, perhaps this one answers the question of "why not take it?".
  15. Amen to that. It seems all the Abrahamic religions pray in Hebrew.
  16. If 100% of the people were vaccinated the virus would still cause some infections- no vaccine is perfect. And you could then publish scaremongering stats that say "everybody in hospital with covid was vaccinated". And you could even try to imply that the vaccine makes people more susceptible. Bu that would be a lie, wouldn't it? In Israel the vaccination level is pretty close to 100% so anyone with any sense would realise that many or most of the cases were going to be among people who were vaccinated (especially since the elderly tend to be more susceptible and more likely to be vaccinated. So that graph doesn't show any problem with the vaccine. It should be considered in context. The contexts is that the other trials of ivermectin did not show it to work. The trials (and lived experience of people protected by) the vaccine shows it to be quite effective. If you only have money for one, go for the vaccine. If that is not available, buy a mask; it's not very good, but it's better than horse wormer.
  17. Just a quick note for the selfish idiots out there who don't think we should pay to vaccinate people in other countries. Where do you think the new variants will come from?
  18. Everyone makes mistakes. You were honest enough to admit it. That makes you one of the good guys.
  19. And look at how much more effort has to go into looking after them. It's obviously possible to farm bullrushes. I'm less sure it's worthwhile.
  20. That's right; we can harvest it , take the roots, make them into flour and then next year... No plant actually needs our "help".* They were all doing fine before we arrived. But, if you want sustained yields of the sort that make things commercially viable, you need fertilisers and crop protection. *There's a suggestion that avocados wouldn't survive without us
  21. Did you measure the difference or are we going to have to take your word for it? You could ask the Royal Society about that. But I will assume you are right; there is a difference. As you say, the guitar maker made "small adjustments" to the guitar and that changed the sound. That's certainly a reasonable idea. Now, if we know that small adjustments to the design will give a change in the sound the trouble with the experiment is that we don't have a violin which is identical to the Strad in the shapes and sizes of the bits, but different in the way in which the wood has been treated. Until we make one, we can't do a proper test.. As Enthalpy says Well, so are all the others. There's another wrinkle too. Consider one bit of the instrument- say the bridge. Does the density of it make a difference to the sound? I presume it does. So, when we make our "copy" of the Strad do we choose a piece of timber with the same density as the master? For the sake of discussion, let's say it was a bit denser than most of the wood he used. How do we know if he achieved that sound by choice of dense a piece of wood, or by some sort of treatment or particular choice of varnish? Did he just use thicker varnish? If he did, was it because he wanted the instrument to sound really good a few hundred years after he died rather than "now", when he was selling it to a customer? Because he will have realised that the timber and the timbre will change with time...
  22. The way in which I expressed my point was light-hearted. However, that is no reason to ignore it. Th electrons near the nuclei of atoms are in very large fields and experience huge accelerations- much bigger than those in an accelerator. So, if you think that electrons in an accelerator should emit light due to the effects of gravity, why don't those accelerated in, for example, a sandwich?
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