studiot

If you are looking further into these matters, it would be a good idea to reconsider the phrasing of your question. What you you mean by "... using radioactive decay..." ? Do you mean using radioactive decay of some atom as a cause of the transmutation of itself ? Or are you including radioactive decay of something else to provide radiation as the cause of the decay of some atom that is normally stable ? Thinking about radiation itself is also fruitfull. Radiation comes from to radiate or to spread out in many directions. Clearly when there are only a finite number of paticles radiating, they cannot go in all directions. So studying the pattern of spread is informative.

Note also that strictly the result of both processes is a new atom or atoms and the original atom(s) are used up in the process.

Start here to understand fusion = increase an atom's proton number ; fission = decrease an atom's proton number. Only fission uses radioactive decay for this. https://www.orano.group/en/unpacking-nuclear/nuclear-fission-and-nuclear-fusion-what-you-should-know FUSION FISSION

I thought that might evoke some comment. 😀 Yes I mean wind loading. We have seen the effect in many recent videos of the storms that are sweeping the planet. Here in Somerset it is interesting to compare my house with that of my immediate neighbour's. My house was built immediately pre WWII, when building largely paused and has concrete roof tiles. My neighbour's was built after WWII when building recommenced and has fired clay roof tiles. The concrete tiles are about twice as thick and heavy as the clay ones and did not suffer in the recent spate of high winds. A significant number of my neighbour's (gosh I wish that word was shorter) caly ones were stripped by the same winds. Another comment about materials. My roof timbers are pitch pine, the resin in which apparantly is very protective from woodworm. Post WWII we started using Canadian softwood timbers in a big way and they are not self protecting and have left owners with a big problem.

Not sure whether you are looking at the blocks or the mortar for your foamed concrete ? As @LaurieAG says getting the materials science of both of these components right is very important to the performance of the building. Further there are big differences in the requirements for the blocks and the mortar (which does not function as a glue for the blocks, concrary to popular belief). Cowboy builders sometimes add ordinary wahing up liquid to mortar as a cheap easy to obtain alternative to the proper plasticiser. this works OK for the blocklaying time but is deleterious to the mortar in the long term. Yeah Liverpool Catherdral is a famous example of failure to observe proper masonry practice.

+1 Perhaps I should mention that I don't give a s___t for Jack Bower's toileting habits. 😀

My ground floors were originally traditionally suspended timber, but they had rotted and were very draughty So I opted to replace them with a suspended concrete slab. Reinforcement was required for structural reasons. Ready mix offered to 'include the reinforcement' in the form of fibres (carbon ,steel,glass have all been used). I actually went for traditional steel mesh reinforcement. In England the loading codes are more onerous for floors than roofs. Indeed the loading can often be negative or partly negative on a roof.

Forst of all what do you mean by concrete, ie what is your application ? I ask this because american practice is to use the word cement for what we call concrete on this side of the atlantic. I am replying using the european terminology. Concrete contains inert filler material called aggrgate and binding materials, which are often portland cement as you say. OK so why do you want aerated concrete ? There are three basic reasons for doing this. All use air entrainment (air is the entrained gas, the link gives many types of foaming agents, mostly fancy organic compounds) https://www.sciencedirect.com/topics/engineering/air-entraining-agent Firstly to produce lightweight concrete for structural reasons. Since this concrete is also structural, lightweight aggregate is used along with normal grading. You can even go as far as polystyrene aggregate replacement in suitable parts of the structure. Polystyrene beads are entrained in the mix. Secondly for frost resistance on non reinforced mass concrete. Here larger sized aggregate is often used (40mm and down or even bigger as opposed to 20mm or 10mm and down) as this is cheaper. These would be stones of normal weight. Medium air entrainment would be added at mixing We call this 'bus bay concrete' but I can't see you needing any where you are. Finally air entrainment is used in the concrete to make lightweight thermally insulating building blocks All these blocks are again lightweight and there are various grades. However since the prime purpose of such blocks is insulation rather than structural a variety of pulverised aggrgegates are used, depending upon what is available in the area of manufacture. These pulverised aggregates are often already partly entrained so need less air entrainment with the binder. Does this help?

Beware I have a lawyer named Turpin. 😀

😀

If you are so worried about that you will have to visit the BBC news site.

When I was a small child I was very worried why characters in films and books never went to the toilet.

This is the book section of the general forum. I just thought that someone might find the article interesting.

Since they say the library is 600 years old I assume it means older than the USA.

Wouldn't that mean that they could not pass each other but if one tried to move forwards or backwards faster then another ther would be a collision > We cannot see beyond but we can certainly think beyond... For instance consider any rotation about some axis. The rotation takes place entirely in two dimensions (the plane) But the (unique) axis of rotation is a line that points out of the plane into the third dimension. However in the third dimension there is not such pointing out of the three dimensional lattice, all the rotations and axes of rotation are contained within the 3D lattice. In fact rotations in 4 D do not have a unique axis of rotation.

Sure, our local readymix offer to deliver the concrete with the reinforcement already mixed in .

Sorry the video is just a screenshot, I can't embed this one. https://www.bbc.co.uk/news/videos/cz6l1qw71jyo The library where books are kept under lock and key The library where books are kept under lock and key Step inside the library where books are kept locked to the shelves with chains. The chained library at Wells Cathedral in Somerset is home to a collection of books that are older than America. The majority are Latin transcripts and religious texts, which were handwritten and handmade by monks and scribes. This would have taken months to complete.

That may have been the edwardian view of concrete, Though monsieur Fressynet might have disagreed even then. But fibre concrete has been around for some decades now. When I worked at the Building Research Establishment in the 1960s there was a department working on it.

This was what I was referring to when I said So +1 for acknowledging it and also to MOON for also spotting it. If you want to present the claim that the universe is getting closer to equilibrium you need to be4 able to demonstrate that this is the case. For this purpose you need a measure of the 'distance' from equilibrium and be able to show that this is decreasing. Furtjer you need to somehow include all forms of 'equilibrium' (mechanical, thermodynamic, chemical and so on) and if necessary a separate measure for each and, if possible, some sort of combined measure. You mentioned somewhere that you are interested in scinece and in philosophy. Both disciplines require the presentation of rational chains of thought leading from premises to results. Additionally scinece requires observational/experimental verification of these results. Hindcasting is often employed as a veracity test before any credence is put into predictive results (forecasting). Maths is useful but not essential to either. Here is a superb example of such rational thought from a mid 20th cent professor of geology with not a shred of maths used. I have starred the relevent 4 lines of text, but Proff Sutcliffes's style is a nearly impeccable model. It is not a secret. I watched an hour's ( NASA) documentary on the BBC on the NH space mission made after the probe suddenly came back to life and transmitted the astounding pictures and data. Google : NASA video of New Horizons flyby of Pluto. https://science.nasa.gov/toolkit/new-horizons-flyby/ Note The BBC and PBS America both produce some excellent scientific documentaries. The BBC ones are often also available on DVD. If you want to look at the experts presentation of the state of the Earth's Early atmousphere in realtion to evolution look at the Professor Aubery Manning ( a biologist) series where he visits paleobiologists around the world who present their results and conclusions in 8 one hour lectures. It is interesting to trace how the knowledge and conclusions stood or changed in the three series. Stewart 1990s Manning early 2000s Packham 2023

Have you heard of the 3 point Cradle to Cradle Philosophy ? https://mcdonough.com/cradle-to-cradle/ The original book is available very cheaply SH and very thought provoking. https://en.wikipedia.org/wiki/Cradle-to-cradle_design https://c2ccertified.org/topics/built-environment Universidad EAN in Bogotá, Colombia is a groundbreaking redevelopment project that demonstrates Cradle to Cradle Certified® design and circular economy principles. © Jairo Llano – LlanoFotografia

Well welcome to both of you. Keeping an open mind is what is necessary. Science is all about evidence, and weighing carefully that evidence. One thing that means is making the appropriate reactions and changes when new evidence come in (which also has to be weighed against the existing). A great deal of very solid Science has been carried out at the behest of one religion or another, but Science as a whole has yet to find any evidence of a deity. Meanwhile many religions offer a worthwhile code of conduct.

Does it ? and there is me thinking that four-vectors are something to do with abstract multidimensional spaces, which are algebraic, not geometric.

Actually that is why we were forced to do so many repeat experiments at school and university. I remember measuring g, e/m, the mechanical equivalent of heat, the spectroscopic signature of many organic compounds, and many many others.

Of course not only does the concept of randomness exist, it is all around you all the time. However it is useful to get our definitions correct (is English your first language ? ) so here is a small adjustment for yiur vocabulary. 'dices' is what a butcher does as in Henry the butcher dices and slices the meat. 'dices' is the third person singular of the verb 'to dice' which means to cut (approximately) into cubes. The noun (object) you are thinking of is the word die, which has a plural dice. One die two (or more) dice. That said it is necesary to distinguish meanings for the words random, statistics , probability, event and perhaps a few more. So when a process or activity has more than one possible outcome such that the outcomes do not occur in a defined sequence, that those outcomes are defined as random. Each single outcome is also called an event. Given this definition you you not need to know anything about probability, statistics and so on, you only need to loo around you to see many outcomes that are random. So some examples may help. If I have a bag that I can't see into and put two balls into the bag, identical except one is blue and the other is red. Then I withdraw one ball by feel alone and find it is red. Withdrawing the first ball is random as there are two possibilities; red or blue. Withdrawing the second ball is not random, it must be the second colour (blue in this case) so the second withdrawal is deterministic. Each withdrawal has been considered as a separate outcome or event. Considering the two withdrawals as part of the same single event of withdrawing both balls from the bage yields a different analysis. Can you see why ? This second view held probability theory up for something like 200 years. More widely, suppose I do some target practice with my bow and arrows. I hang a target on my neighbour's door and shoot a number of arrows into it. Each arrow hit is a single event. Once I have made a number of hits I will notice that the arrows do not all hit in exactly the same place, no matter how hard I try. This is because each arrow flight experiences random influences such as gusts of wind, which blow or do not blow and so on. So my arrows are truly scattered randomly over the target, as I am not superman. Turbulence in the air is probably the widest random influence we experience. Does this help ?

Should you be interested there is another thread proposing the same argument. This thread contains a good short summary of the necessary mathematics of probability by another Member. It is the third paragraph of post number 12 (from KJW) on page 4 of this thread. I'm sorry I don't know how to send you directly to it.