studiot

I am saying that whilst the term hypothesis is a general scientific and philosophical term meaning a proposal that may be (is hoped to be) valid, the term 'null hypothesis' is a specifically statistical term that means something more and has to be set in a way that can be numerically compared. There is for instance a form of descriptive statistics that cannot have a null hypothesis. How does that square with the opening post examples ?

I was coming to that but it will entail you knowing exactly what 'energy' is. Being a science novice is just fine; one of the main reasons for this site to exist is for novices to ask questions. So this is not a criticism, but I suspect you think of energy as a sort of thing or substance of some sort. That is not the case. Energy is a property of things and substances. Scientists often say loosely that 'energy is transferred' whilst they actually (or should) know that 'energy transfer' is really an accounting device. 7 take away 3 leaves 4. You question about loss into is similar. I hope you can see that the 3 above does not evaporate into space. As a physical example let us consider boiling a kettle on a gas hob. The burning of the gas raises the temperature of the gas particles, which means they move faster. When they strike the bottom of the kettle they slow down - we say energy is transferred to the kettle, but what we mean is that the impact of gas molecules makes the kettle walls vibrate faster than before we heated them. In turn the kettle walls transfer some of this additional motion to the water inside which means the water molecules now move faster, eventually fast enough to boil. Working out all the maths of this chain of events takes several pages. Far easier to just say X amount of 'energy' is transferred from the gas to the water. So when you are asking about electrical energy dissipated to space what exactly are you thinking about and why do you think the conductance of space (if any) plays a part ? The better you can explain your question the better will be the final answer. Incidentally we do say that all bodies give off and receive electromagnetic radiation at all times which results in a transfer of energy. But this is a thermal process not an electric one.

Since about 3 upgrades ago (thank you IT whizz kids) preview has been pretty clunky. Most folks soon find out that if you leave the thread and then return to the post the missing presentation will be correctly displayed. But no, preview itself often doesn't work. How did you get on with my suggestions about Charmap and super/sub script ?

Indeed not. But then adequacy, internal consistency, external consistency, and fruitfulness are not scientific terms in general nor statistical terms in particular. Think about it. You have already stated the difference between a statistical hypothesis and a logical conclusion drawn from premises., notably you have several hypothesis any of which could account for the data. That is the null hypothesis only ever concludes that the hypothesis could account for the data, and usually that it is the most likely of several hypotheses It never actually concludes that the hypothesis does account for the data. By contrast a sound or valid logical conclusion formally excludes other hypotheses, given the validity of the premises.

Obviously this AI has received some substantial 'training'. or, as you suggest there is a man hidden inside the fairground booth as of old. Responses in other threads simply say that the AI claims to only work within material provided, that it does not have access to 'the internet'. This provided material must have been substantial to output both the earlier poem and Ghideon's test.

A No situation exists This assumes 1) That an undefinened term 'situation' is capable of existing or not existing. and nothing else. 2) That statement A is capable of having a truth value. This sort of paradox caused much heart searching in the foundations of Mathematics, particularly set theory, when they were first introduced and still have not been fully resolved. The only thing we have determined for certain is that some part of the underlying definitions have to be restricted. 'Type Theory' was one was to do this by restricting the nature of what can be a 'set'. my underline and nothing else is another way leading to what is called second order logic, with does away with the 'Law of the excluded middle'. Other ways have also been found but we cannot proceed here until you provide / fireproof definitions that you have been asked for. Note the definitions have been spread over several similar threads by yourself and others have also asked for them.

I'm sure it can, but you can also smile ?

Cool.+1 Move over swansont, CHAP is coming.

Things have gor rather hectic here so it doesn't look like I will make a full reply tonight. Anyway the short form is that the electric force is probably the most important force in our everyday world. Our bodies run on electricity. Chemical reactions run on electricity. If you have a fish tank aquarium, you will monitor the water quality using a conductivity meter. The chemical reactions that cause weathering in the rocks run on electricity so conduction in the earth is vitally important to us. This is not the spectacular lightning storm but none the less all due to a form of conductivity unlike electricity in the power wires in our homes. To expand on this I will need to post some basic explanations so more to follow.

Thanks. BTW, I'm not sure brainee has much access to high school education ( that's no criticism) but is trying to get an education the really hard way.

This is an interesting question that has many ramifications in GeoPhysics, but could you narrow it down a bit ? Also you say conducted, do you know the difference between conductive current and displacement current ? Finally the Earth is far from homogeneous and the values for sigma and epsilon vary with local materials eg seawater v granite.

This next comment is very important. The Physics an Chemistry of how what we call electricity is very difficult and complicated. Futhermore there is not one single mechanism, but several. And they all have a part to play. As a result, abstract models of how thing behave were developed, models that show measurable quantities like voltage, current and so on. These models are called circuit theory and are set in the mathematics of the relationships between the various measurable quantities. Have you heard of Ohm's Law ? Of course since they are both approaches about the same thing there is a lot of overlap and common stuuf involved. But there are also important differences and flow is one of those differences. Flow appears in artificial abstract circuit theory, but not really in a physical description of what is actually happening. And flow refers to flow of charge, as Mordred said, or current which literally means flow of charge in electricity theory. Anyway the important thing to remember is to know which version you are using. You ask about electric and magnetic fields, so it is important to know just what a field refers to. A field occurs in a region of space (along a line, on an area or in a volume) for which some quantity has a single defined value at every point in the region. The defined quantity may belong to matter or be totally abstract. So a temperature field or a density field are both about properties of matter that can vary from point to point. A placement of arrows on a weather chart showing which way the wind is blowing and where is purely abstract and called a direction field. An electric field shows the strength of attraction (as a force) that would be felt by a unit electric charge at any point. A magnetic field shows the strength of attraction (as a force) that would be felt by a unit magnet at any point. Neither of these are used much in circuit theory, but both have lots of different uses in Physics and Chemistry, often where there is no circuit involved at all.

OK so here is a further analogy Take a string and either tie one end to something fixed, and then take the loose end and pull it out straight. The flick the end you are holding up and down. You will cause the flick to travel along the string to the far end. You can also do this without tying one end but is is ahrder to get the flick to go all the way to the other end. Now here is the thing. That flick maintains its shape and size pretty well all the way down the string. That flick is a packet of disturbance that travels along the string. That is what we mean by a photon being a packet, but in a way suitable for EM radiation, not exactly the same as the flick on the string. One definite similarity. Both the flick on the string and the photon packet contain more energy than the undisturbed state. So the travelling pulse (flick) is a method nature uses to tranfer energy from one place to another. The next thing we need to do is to deal with fields, but I will stop there for you to digest this and to point you at your electricity question where the discussion of fields is better placed. Then we can return to this thread and complete it.

It doesn't. The hosepipe analogy is best forgotten.

I think Dima uses a translator. His aim was stated very clearly and coherently, as I have already noted. However the conditions he proposed to achieve this aim were not, in fact I agree that instanteity and simultaneity are both nonsense, quite apart from the 'acceleration into a moving frame a v' whatever that might mean. So I described it as nonsense. Your post was next and it could only have been reply to Dima's opening post as it followed on straight after th op (How I wish this forum would go back to its original format and number the posts). But it made no sense either. The cars couldn't have a reference frame once they started moving, given your stated conditions. So if you were trying to say the same as I am now saying, viz that Dima's original aim meant his conditions were inappropriate that's fine, But I don't see it put very well. BTW who is MD please ? I think most participants is this thread know and agree that these conditions are neither necesary nor possible. Ditto Forgive me, I don't see any explicit reference to such a rod, although rigidity is again not the issue. I respectfully suggest that both of you are getting tangled up trying to square the circle and start accelerating all parts of a train both instaneously and simultaneously, with or without magic signalling. If you want to accelerate a train, just tell tha man to put the engine at the front and pull or at the back and push. No part of the train will ever be moving sufficiently fast, relative to any other part of the train, for either SR or GR calculations to be needed. If you want to introduce an outside observer (which may be what Dima had in mind) then again say so and introduce relativity appropriately.

Thank you Mordred, I downloaded the pdf though I have seen some of this before it is more modern than my knowledge.

Are you going to comment on my reply to this ?

In fairness I don't see that allowing the train to turn makes any difference, except to add needless complications to the mix. I don't know if anyone can remember th slow motion video I posted a while back of a slinky being dropped from a tallish building by first letting go the lowest part of the slinky so it started uncoiling, and then releasing the top from its mounting so the slinky as a whole aquired a downward motion, additional to the stretching of the coils.

What do you think the OP's original intention was? He presented a scheme for accelerating all the cars of a lengthy train together, and in another post he explicitly said it would need to be done without signals being sent between cars. I addressed that implicitly in my second post. In order to keep the cars all spaced properly as they get length-contracted, the rear cars have to initially accelerate faster than the forward cars, and then the forward cars have to catch up later. Actually he didn't. What he actually said, in a rather strange style, was If we want to accelerate a very long train. which makes sense. The next part was nonsense. So we are left with wanting to accelerate a conceivable physical object to whit one very long train. Perhaps that is what led you to make the next post which also seemed nonsense to me The differential timing of the motions between adjacent parts or sections of the train in the limit tends zero as the initial distance between the sections of the train tends to zero. This is the condition that allow the train to move as a whole. This will happen quite naturally in an orderly fashion without all the paraphnalia later described. It is also the 'long rod' example as Mordred has pointed out.

I feel this train is running further and further down the track of fancy, rather than fact and further and further from the OP original intention. This is another way of putting what I said earlier, though I didn't know it was called Born rigidity I can well believe that this line of thought was started by Max Born, he certainly discusses it in his book. No one has yet replied to it.

Kinematic treatments are point particle by nature. Furthermore in both SR and GR, as far as forces can be considered at all, the Newtonian condition that internal forces cancel out when considering systems, does not apply.

That's a good way to confuse you readers, but thank you for the reply. Talking of reading, I listed four undefined terms, you have only answered about one of them. No they can't be. Dates have a reference zero. It is one of the basics of relativity that there is no such thing as a reference zero. By the way, welcome and please note new members are allowed a total of 5 posts in their first 24 hours as a very effictive anti spam measure. So use your last one wisely, (I can happily wait another day for my next answer).

Nice point +1

Thanks for the reply, but you seem to have missed the point of the article and my headline question. The sham they called the recent climate conference (COP27 I think) produced at least one good result. Namely that richer nations are putting some resources into helping poorer ones play their part. To me at any rate an, I would think it would not take much of this money to help extend seagrass and also mangrove margins. It is also true that the oceans were and still are the largest carbon sinks on the planet, so it make real sense to promote their function.

interesting. +1