studiot

I like to have my own copy of things. But I also thought you would understand more. I don't know where you found that article, but it is part of the Stanford Encyclopedia, which contains many many articles, with a choice of formats. Paid members may download any of these. Like our member with the cigar, I support Wikipedia with a few dollars a year and thought I would like to support the Standford project with a few dollars more. Neither are greedy unlike some sites. yes, I was going to ask about this. But I don't see any conspiracy background, just a member whose first language is not English struggling with a translator. 🙂 Yes that is also my understanding so far.

Thank you for that knowledgable amplification.

How do you address my point about two of these being irrelevant ?

Glad my reply was of some use. How did you get on with my little quizz ? It was designed to demonstrate something very important. Mathematics uses the + and - symbols for two different things. This sign of something which you asked about - which is a property of that something and addition/subtraction - which is an operation or process on that something Many people get confused about this basic point.

It would seem to be that however small the risk might be it is not insignificant since the BBC recently highlighted cases of misdiagnosis and I find on looking for them that there is an american standard on the subject. https://pubmed.ncbi.nlm.nih.gov/25944182/

Still considering basic mechanics. You have correctly distinguished between rotation and spin. Do you understand the difference ? Gaseous atoms do not rotate. But they do spin. They have no internal axis to rotate or tumble about, unlike molecules. They do not rotate about external axes because their motion is random. Gaseous molecules can spin, they can also rotate about non centroidal axes within the molecule, but they do not rotate about external centres as their motion, like that of atoms is random. You should also reconsider your proposal for momentum transfer in slowing things down. The direction of impact in relation to the centre of rotation will determine its ability to affect rotation about internal or external axes and to affect spin. However this is just a coarse classical start. The next step is to realise that with atoms and some extent molecules the mechanics is more subtle because both have structure. Since in a semi classical analysis you have spinning electrons orbiting a massive nucleus, like the Earth and the Sun, you have angular momentum for both spin and rotation combined. This situation becomes at the same time both simpler and more complicated/difficult when you consider photon atom/molecule interaction because the scale of things is such that you need to move to quantum mechanics to obtain correct models of the interactions. It is these interactions you need to consider here. However it is you proposal and your thread so it is up to you to work through the detail, rather than just guess.

What is hyperloop please?

Does it ? Take a ball such as the Earth, which has a spin about its axis and a rotation in the plane of the ecliptic. All rotations are planar motions so adding or subtracting momentum perpendicular to this plane make no difference to the rotation ie no braking effect for 2 of the four possible directions. Also 'tapping' the Earth at the north and south poles, along the line of the spin axis does not affect the spin. That leaves 4 direction out of 6 as I said. Have you not mentioned spin reduction here ?

I suppose that depends upon which presentation you download did you download the HTML version ? I said I downloaded the pdf presentation, which comes in two flavours. US and A4 paper sizes. I chose A4, which is clearly paginated, as are all pdf documents as far as I know. Anyway, since I can't copy and paste without loosing the the symbols from the pdf, here are a couple of screenshots, note the pagination at the bottom corners. Thank you again for the reference excellent and seems bang up to date as practicable.

Lots of combinations work well in milder climates. The real point is that users want/need the heat and power mostly in the winter and also the dark.

You keep mentioning "all 6 directions" as though 6 was some magic number. Do you not realise the basic mechanics that momentum directed along 2 of those 6 directions cannot affect spin? You are just throwing things out without thinking them through.

No one said that it is not a beneficial or desirable process. But this is a technical discussion about technical issues involved in achieved a desired objective.

Rubbish. I doubt we shall ever know what the first human belief was. It may have been "I am going to have roast mammoth for dinner"

Actually page 45 of the stanford link you provided (I have already thanked you for the link, paid my $10 and downloaded the pdf ) says rather more, particularly on page 45 et seq. As always the devil is in the detail.

It's a dumb photo. I'm sorry but this must be the worst ""What is this please ?" photo I have seen since I joined here. That is set in the context of maybe one such request a month on this site. I couldn't understand this one, let alone identify it. Post a half ways decent photo, or better set of photos, without the fancy editing and you might be suprised how many responses you get and how good they might be.

Problems yes, but this is the big one, even though it is a single small word. 1 The basic problem is this. Nearly all forms of 'environmental' electricity generation are a form of collection of low density energy and are inherently low voltage. This requires the parallel working of many units of generation, whether wind farms or solar or other. All this low grade supply has to be commoned up to a single output, which is technically very difficult and can be very wasteful if not done well. How would this work on a massive scale in the Sahara ? 2 Not just sand but in particular sandstorms ! 3 You are right, transmission is a difficulty, and needs to be at high voltage to avoid losses. Note my point 1 for the necessary technology to achieve this. However how do you think transmission takes place from Which are mostly offshore ? Further, you may like to know that the UK already buys (nuclear generated) electricity from France via a massive underwater cable across the English Channel. 4 So what happens when the sun isn't shining ie at night ? Yet again a storage and recovery issue

I see that you have satisfied your original request and also received some excellent advice. So I will just add a couple of extras. Firstly as you see you can always come back here and receive good quality help at any level. So if you have any specific questions, don't hesisitate to ask. Another friendly and helpful site is https://mathforums.com/ Although like all maths sites they suffer more than SF from spam. As too your subject matter: You have asked about signed numbers - a subject that many have trouble with. To fully get the most out of this you need 1) To properly understand the use of brackets (parenthesis) 2) The standard order of arithmetical operations 'BODMAS' or 'PEDMAS' Then you will be flying. This sounds fearsome but if you can correctly interpret these X = 2 + (-3) & Y = 2 - (-3) you will be well on your way. Comeback if you want more

1) That's an assumption not an answer. If this stuff is buzzing about the universe it must collide with other stuff, just as does ordinary (sub light) matter. So are you saying that the laws of conservation of momentum do not apply to such collisions either with ordinary types of matter or with more superluminal matter ? I asked why this assumption is justified. 2) I didn't ask about detecting the dark matter in question 2. I asked about detecting the emission radiation, that you say exists from superluminal matter. Or are you saying that there is none whatsoever in our part of the universe ? Again why can't /haven't we detected this ? However thank you for your answers.

Thank you so much for such a comprehensive and well thought out addition to the discussion , including the links. +1 This will take much thoughtful chewing over and investigating.

1)So what would happen when this superfast matter hit something ? Wouldn't we see evidence of this ? 2) If this superfast matter emitted light wouldn't it travel at normal lightspeed? So why couln't we measure that ?

I don't know your purpose in asking this question however a small, but important point is worth making espcially if you are an arts person. A force is a push or a pull. In the body the muscles can only pull. There is no mechanism for directly exerting a push. To obtain a push Nature causes the pulling muscle to pull on a stiff object ie a bone. This causes the other end of the bone to push against something. Muscles always work in opposing pairs and the balance between these two muscles determines which way the pull occurs. Often one half of the pair is (much) weaker than the other so for isntance a crocodile has very powerful closing muscles onhis jaw but much weaker opening ones. In relation to your question, arms hang down so they are pulling on the rest of the skeleton. So only body parts (ie muscles etc) that are involved in pulling are needed to stop them falling down. That is why there no direct connection to other bones is needed. In contrast our knees are held down by the weight of the upper body pushing down on the pelvis/thigh and eventually knee bones.

Do you think lack of change is unimportant?

Good to see you in action again, Eise. Welcome back. It is always a pleasure to have your clear thinking in a discussion. +1 and yet You various examples assume that there should/must (since the imperative is used) be one and only one capable of dealing with a given phenomenon. One of the principles of modern science, technology and general work practice is the principle of independent corroboration or check. That is arriving at the same result by different routes. Another example of differnt routes lies in the difference in the way a modern computer reaches an output versus the way a human migh do this. The computer takes lots of small simple steps but very quicklyso that the computer can arrive at a result in milliseconds that woud take a human a whole lifetime to reach by the same method. Further examples occur where a method we know to be theoretically unsound, arrives at the same result as the more complicated and long winded 'proper' method. For instance the method of virtual displacements, D'Alembert's method etc. Perhaps @Col Not Colin was getting at this sort of thing in his post ?

I have absolutely no idea how this would happen, but isn't that exactly what the word condense means? Isn't that what happens when a gas condenses to a liquid or a liquid to a solid ? A new form of PE is aquired - surface energy.

Unless the cloud can convert KE to PE somehow, since temperature is a function of KE, not PE don't you think ?