studiot

What do you make of this russian expermental treatment in the light of you 'all good and luvy duvy' claims for these hormones ? https://siberiantimes.com/other/others/features/beating-addiction-out-of-you-literally/?comm_order=&c_page=3

Four good books on geometry, curvature and gravity Norman Johnson : Geometries and Transformations - Cambridge https://www.google.co.uk/books/edition/Geometries_and_Transformations/adBVDwAAQBAJ?hl=en&gbpv=1&printsec=frontcover Frankel : The Geometry of Physics : Cambridge https://www.google.co.uk/books/edition/The_Geometry_of_Physics/2iq2EGNgX24C?hl=en&gbpv=1&pg=PA4&printsec=frontcover Frankel : Gravitational Curvature : Freeman https://books.google.co.uk/books/about/Gravitational_Curvature.html?id=ryPyfLsgmhsC&redir_esc=y Sternberg : Curvature in Mathematics and Physics : Dover https://www.google.co.uk/books/edition/Curvature_in_Mathematics_and_Physics/CUDDAgAAQBAJ?hl=en&gbpv=1&pg=PA19&printsec=frontcover

Go on then give details please? It's easy to say, not so easy to implement.

Good breakdown of your analysis, John. +1

I wonder what happens when one of these automated vehicles simply runs out of fuel ? If the AA or RAC are to be believed this is not an uncommon occurrence on UK roads with human drivers.

Thanks for both your comments about the trampoline and reminding me og that book. I looked it up again and this time found a sensibly priced version. +1

GI brown, despite his initials, was not in the american military he was a humble chemistry teacher, and author of a famous Physical Chemistry textbook. Amongst his other books was this history of explosives https://books.google.co.uk/books?id=PzXcAAAAMAAJ&dq=editions:ISBN075091923X

thank you for this useful information. I have learned something. But sadly, if you continue to talk down to other folks in this manner you will become pretty lonely here.

Not at all sure who your target audience is here. Are you asking 'kids' to think in the abstract, when they have not encountered enough concrete examples to compare with ? The most motivational thing I saw was starting Physics with a bunch of other 12/13 year olds in a coeducational school. The (lady) teacher's topic was 'Forces'. Please pause for a moment and ask yourself how you would approach this for a class of such kids ? before you look at the spoiler.

And there's me thinking that his works were of great length! 🙂

Please be aware that I was referring very specifically to the trampoline analogy when I talked about an extra dimension. The dimension is in no way "higher" than the others by the way, as they are all supposedly equivalent. For the trampoline the extra dimension is required. It is worth noting at this point that gravity is a distributed function or effect with a possibly different value at every point in the space concerned. This is why in the Newtonian model it is called a "body force" as opposed to the line segment vectors of contact forces. It is possible to modify the trampoline model by introducing a variable stiffness function, and perhaps extending it to 3 dimensions like a sponge, which would then produce the effects you show at the expense of considerable mathematical complexity. This could reproduce the animation shown. This is reminiscent of the efforts scientists made in the past to preserve the heliocentric model of the solar system by introducing cycle upon cycle to account for the observed movements. None of this gets away from the problem I stated earlier. The trampoline model, being a purely mechanical force model, requires that extra dimension. It is well known that the vector product in 2 dimensions automatically takes into the third known dimension. But there is no known corresponding effect in 3 dimensions that requires a 4th to operate. Rotations and other vector products are 'closed ' is three dimensions and only produce all their known effect within that 3D space. That is why, in my view, the trampoline model is counterproductive.

I thought perhaps it was for a story. +1

The short answer to your question is yes, some smouldering fires would continue to 'burn' unaided. Perhaps you remember the Monkees song 'Pleasant Valley Sunday' ? The line 'Charcoal burners everywhere' is relevant. charcoal is what happens when you burn oxygen in reduced oxygen. There is a nice chart for different fuels showinf the 'Limiting Oxygen Concentration' on Wikipedia https://en.wikipedia.org/wiki/Limiting_oxygen_concentration

More specifically it is the nitrogen in the air. This is why to dive deeper, where there is greater pressure, special gas mixtures without nitrogen are used. Endy does have the right idea about expansion being the cause of the the trouble so to answer your query more fully, you need to know two things. As pressure increases more gas dissolves in a liquid (water, blood, cellular fluid etc). Dissolved gas is no longer a gas but part of the fluid. If the pressure is then reduced the additional dissolved gas returns to being a gas, as Endy says. All the fluids in you body have to be at the same pressure as the water at any particular depth or they would be squashed into a smaller space. This is not like a submarine where there is a rigid (metal) shell to resist the difference between the external water pressure and the air pressure inside the shell. So the air you breath when diving is at higher pressure than in the open atmosphere. So more of the gas dissolves in your blood stream. As you return towards the surface the pressure regulator in your air supply reduces the air pressure to match that of the surrounding water at your depth (obviously it also increases the air pressure as you dive deeper - this is all automatic) So on return some of the gas emerges in your bloodstream as bubbles, nitrogen being the particular problem. Your body can only clear these bubbles at a limited rate so if you ascend too fast they build up. The Bends occur when uncleared bubbles start to acumulate within the rest of the body, particularly around the joints in the skeleton. This is why you ascend slowly and in stages if you have dived to any significant depth. Does this help? Feel free to ask for amplification of any point.

Here is some useful beginning information from this book which makes good bedtime reading. Peter Collier didn't understand it either so he taught himself from the ground up and wrote a book about it. hint Click on the image to get the full size

Simply put the trampoline is a 2D membrane that is distorted in the third dimension by a force acting in that dimension. That's all fine and dandy, but we live in a 3D universe - as far as we can tell there is no 4th dimension - but scaling up the 'trampoline' would require a 4th dim. There are proper astrophysicists here that can offer multicolour explanations @Janus?

Yes indeed, but are you not doing the same ? I clearly remember having hammered into me "You cam't take the square root of a negative number" Then some years later I learned about imaginary and complex numbers. You keep saying 'even light...etc'. But you should be concentrating on the 'black hole'. Remember that the original black holes - invented by the mid victorians - were introduced as the nearest thing man could make to a 'black body'. But light - in the form of IR and microwave - certainly escapes from these. Indeed it has a temperature that can be measured. So perhaps the 'even light' was meant to distingiuish those original black holes from the populist term coined much later . As to lying to children, saying even light cannot escape, is not strictly true, just a populist presentation that is nearly true. For a more accurate, but still childlike, exposition see here https://www.universetoday.com/152547/we-knew-black-holes-have-a-temperature-it-turns-out-they-also-have-a-pressure/ We have had several threads here discussing how poor and inaccurate the trampolite / stretched blanket analogy is for GR.

Well this plays nicely with the other discussion about socialism + insurance. To answr phi the american insurance indistry pioneered the use of Bayesian statistics when everyone else (mathematicians) was ridiculing it. In those days the idea of insurance was a socialist idea of 'collective risk sharing' - that is the many collectively paying for the harm suffered by a few of their number, noting that the harm could be much greater than any individual couls support. The operative word there being risk. I seem to remember an older idea of business in general was the taking of a risk in order to receive benefit (profit). These days business seems to be promoting the idea of "business want certainty".

Well here is some better news to be pleased about. https://www.bbc.co.uk/news/science-environment-66464437 How is sign language adapting to climate change? Published 12 hours ago Watch: how do you sign 'carbon footprint' in BSL? By Victoria Gill Science correspondent, BBC News For deaf children, teachers and scientists, talking about things like "greenhouse gases" or "carbon footprint" used to mean spelling out long, complex scientific terms, letter by letter. Now they are among 200 environmental science terms that have their own new official signs in British Sign Language (BSL). The deaf scientists and sign language experts behind the update hope the new vocabulary will make it possible for deaf people to fully participate in discussions about climate change, whether it's in the science lab or classroom. "We're trying to create the perfect signs that visualise scientific concepts," explains Dr Audrey Cameron. Dr Cameron, who is profoundly deaf, leads the sign language project at Edinburgh University, which has just added the new terms to the BSL dictionary. ....etc

Generally a well mixed life/career probably with lots of interesting stories along the way. As for trigonometry and mathematics in general, we ar estill teaching maths as a series of procedures leading to formulae that most folks then 'plug and chug'. It follows that they need the manupilative skills to chug. In actual fact most folks never need to do this as the outcome is already has already been worked out or in most modern times is available in the form of online calculators. What they actually need is a simple appreciation of what the result means and what they could do with it. This applies to calculus as well as trigonometry. They can very quickly get the hang of sin and cos or dy/dx etc just as they can get the hang of a car accelerator, brake and clutch pedal, without all the fluffy mech eng gear and transmission theory.

I get that on any browser in WinXP. I am unable to type anything into that thin input editor box. yet I can type into the login box

See also the longer BBC science article. https://www.bbc.co.uk/news/science-environment-66407099

A couple of associated observations. First one of my own on a recent visit to the National Aquarium in Plymouth. Here they have many viewing 'portholes' into various tanks. Some of these portholes have a hemispherical window to give a fisheye view of the interior. So the setup is similar to the glass ball @JeffJo posted and earlier picture to. However the lighting is inside the tank so on the opposite side from the viewer. I looked very carefully but could discern no rainbow halo. This is in accordance with Met Office stipulation that the viewer has to be between the light source and the reflecting/refracting ball. Secondly here is an interesting associated phenomenon as recorded by the joint French - Spanish survey to measure the shape of the Earth.

I'm sure we are all well aware of at least the basics of how insurance works and that it can work for both many socialist (in the broadest sense) and non socialist societies. Actually I'm trying to find some solid foundation to this thread which has the makings of a good topic, but seems to me to be floundering around all over the place. It's your thread. Perhaps we could examine societies for which 'socialism' presents special difficulties ? For instance take the Modern day Outback or the pioneering North America. Self reliance was /is possibly the greatest virtue where folks live hundreds of miles from the nearest neighbour. Or societies that relied on slavery. Is there any point insuring your 'asset' if there is a ready supply of replacements ?

What does a discussion about insurance have to do with socialism ? Also I don't know how young you are, but have you heard of the 'National Socialists' ?