studiot

Perhaps not. You haven't responded to my comment about a positive displacement pump, (amongst others). Do you understand the significance of this ?

A truly excellent reply. Clear, compact and pretty complete. +1

And a nice pleasant discussion to you to. Since the list has no end, the convention if you are going to use 'n' , is to place it between two ellipsis thus 1 2 3 ... n ... The elli[psis is used mathematically as a symbol to mean 'indefinite continuation' . Normally the list would be displayed horizontally, but vertically is OK so I have followed your lead in presenting it this way.

I have been looking at some hard fact and figures. Most importantly there is only one type of pump that would move material (either liquid or sludge) from the bottom of the (shallow part of) ocean to the top. That is called a 'positive displacement pump'. The only such pumps of any size that I have any experience of are pumps for placing fresh concrete. Putzmeister say their pumps require 10 - 40 kg of fuel per hour to place 30 to 120 cubic metres of concrete. 10 kg of diesel releases about 24 kg of carbon dioxide in the process." So I ask again, "How much sediment needs to be lifted and what are the financial and economic costs of doing so ?"

That it works is not in doubt. But the thrust of my comments relates to the sheer scale of the pumping required. I note Ken Fabian has also picked this point up. I had hoped that some of our Chem Eng members might have useful information to add here ? But some further thoughts. Most of the waterculturally useful sediment is generated close to the continental shelves. In the last few years the effect of submarine landslides off the ends of the shelves down the continental slopes has been studied and it's extreme significance realised. The University of Otago leads in this. These landslides stir up and distribute the waters and sediments over wide areas, with noticeable increase in marine life activity. But this lead on to a comparison with the land. According to United Nations Sources, only 38% of the land surface is agriculturally productive, but worse this 38% is being annually degraded We also know from examples around the world that this process can (and should) be reversed. We also know the difficulties of farming in 'poor soil' and of improving that soil. So cost and effort comparisons need to be made between your pumping requirements and recovering and extending current agricultural land. Finally watching Attenborough's latest offerings bring out just how transitory these large schoals of fish are. How would you stop the fish just swimming away ?

Didn't you have a very long thread about this once before ? I thought we had cleared up your misunderstanding but you are making the same mistake again. There is no 'n' at the end of the list An infinite list does not terminate,, by definition. But trying to write an n at the end implies that there is a definite last number, n.

Thank you for the reply. The browser I was using was \m/soft Edge. This has been 'told' to many time to count, not to remember any usernames or passwords etc that seems to be reset to the default every time this browser gets forcibly updated, which seems to be about every other day. I can tell you some good news, however. Edge seems otherwise to be presenting much better view of SF these days, without all the interfering popups blocking views of the meat.

Interesting suggestion +1 To see how well it would/could work you would need to develop what amounts to a full business plan. That explores and answers questions like How much sediment would need to be pumped up to produce how much plankton which would deposit how much limestone over how many years. What would be the eco-nomics ( ie the gain over the cost of fuel) of pumping that much material. Nature already does it in the Southern Ocean; some figures are availble as a start here bg-11-2635-2014.pdf (copernicus.org)

That's good you know this point. But you have yet to understand it. Draw a vector triangle for the contractions, giving due consideration to the shape of your Vs. Parallel to the direction of motion you have a very short distance, just the thickness of the lines in your drawing.. So this component of the total length change will be very small indeed, as a fraction of an already small quantity. At right angles to the direction of motion, ie across the wings of the V, you will have exactly zero contraction. This is the other component of the triangle whose hypotenuse is the length of wings of the V as drawn or observed. Put these two components of contraction together and the result will be an almost imperceptible flattening of the V, until at light speed it appears completely flat. Conventionally we apply the length contraction to significant distance such as the distance travelled, not the size of the travelling objects, which are often considered as point particles, as in the PI-Meson example I gave and you did not reply to. I have set aside for the moment matters of this fluid until the basics relativistic mechanics of the travelling objects is resolved. I am sorry that I am no ,longer able to post maths or pictures on this website.

There is no paradox, just a failure of analysis. What exactly does 'Relativity (SR) say about length contraction ? How far have you studied it ? This scenario is a more complicated version of the PI-Meson first direct experimental proof of SR. Your analysis above directly violates the second part of the statement of SR, Notably "In the direction of motion"

I have just started a new thread. When choosing the thread name the computer offered the name of the previous thread I started in an automatic drop down box. What a pointless waste of computing power and resources. It could even encourage those who have been prohibited by a moderator from raising a subject again to break the rules an start another thread on the banned topic. I can't tell if this is part of the new site software or a W10 'Helpful' update. I also get a drop down list of every email address that has ever been used whenever I login to SF on this PC. What a security risk, not just to say that none of the entries on the list is helpful as my username is not an email.

A most interesting piece of conservation by the RSPB (Royal Society for the Protection of Birds) at a small river in Cumbria, called Swindale Beck. For the benefit of non UK members, the RSPB owns some very important wildlife sites around the country and has promoted some innovative and imaginative successful conservation projects. But what they say about the river and environmental change is very interesting and encouraging. How 'rewiggling' Swindale Beck brought its fish back - BBC News

Firstly there is no law of conservation of kinetic energy, only conservation of total mechanical energy. Secondly there is no need for magic or dragons as objects with mass obey the laws of mechanics without fuss or bother. This includes the common situation of variable mass, for example a rocket steadily looses mass when the motor is firing. Please study the proper laws of basic science more thoroughly before guessing.

I've been saying this for years. +1 I was told this by an American fellow student many years ago, "It used to be the duty of every citizen to waste as much as he can. But there has been a breakthrough and it has now been confirmed that Big Government can waste far more efficiently and in far large amounts, than any citizen. So all citizens can stand down from this duty as their government will do it for them"

Thanks to all responding. I obviously didn't bring out my point that old farts have grown up needing to exercise their brains, but yours folks less so. So the question might be rephrased, should they be concerned ? But please discuss around the subject, that was the idea.

I have several comments to make about your presentation. First and foremost, since your argument appears statistical in nature, the fundamental rule of statistics states Correlation does not imply causation. Further your correlation only appear to cover one solar year. A rather tiney sampling period for geological history. You offer some very pretty gnomic diagrams, and ask for sources of more data. This study covers solar wind data for a longer period, along with plenty of references. Three-dimensional exploration of the solar wind using observations of interplanetary scintillation - PMC (nih.gov) Further they call your 'spirals' ' - magnetic flux rope.' You do not ask for geological eruption data, but here is an excellent book Clive Oppenheimer Eruptions that shook the world Cambridge University Press 2014 I note you are still linking to off-forum websites in spite of being directed not to do so by a moderator in your previous thread.

The last 100 years or so has seen a steady reduction in the mental agility required for ordinary everyday living. Folks no longer need to work out weights and measures, or calculate prices, totals or change to be given. Modern 'scales' do all this and more. You can just wave your phone or RFID card at the bus driver, sometimes you don't even get a ticket or receipt. Reading is no longer required. No it is conventional wisdom that as we progress through life and grow into old age, physical exercise is important towards retaining good physical health and agility. So the question arises does the same thing occur with mental agility ( I can include mental health if you like but please don't concentrate on that) In other words should we also use our brains or loose them ?

Yes you are right, the formula is R^2a/2 = a/2 in this case, so it does fit +1

How does that work out with Dima's equation2, given that the standard area for a sector is Ra ?

Firstly @DimaMazin Please number your equations for discussion in future. Calling them 1, 2 and 3 in the order in which they appear in the OP, This is not a valid question. Equation 1 may be simply derived from equation 3 and is an identity so valid for all values of a, where a is measured in radians. Since I can no longer use either of my maths computers here you will all have to put up with crappy english language. The standard expression for the area, A, of a segment of a circle of radius R is A = R^2/2 (a - sina) Since you say R = 1 We have (Pi - 2) / 8 = 1/2 (a - sina) Multiply through by 2 ( Pi - 2 ) / 4 = a - sina Which is your equation 1 Perhaps you are looking for an angle a where the area is the same for both sector and segment ?

I did consider the difference between draw and specify. Of course if we were Euclidian geometers, as implied in the op then we would have to construct a triangle. But this was not the question asked in the op. The op asked for the form of the general triangle, noting that it would not be achieved by drawing. This was the question I addressed. Not at all. Continuing the mathematical theme (this is after all a mathematical question) my use is a great example of what is mathematically termed a cyclic group of period 3.

But my counterpoint was that you are mistaken about this. I noted that there is no distance, no matter how small or how large that cannot (in principle) be traversed in either direction. There is no precedence theorem such as causality which only applies to time. That is therefore quite a different situation from time where, for any A < B there is only one way to get from time A to time B and there is no way to get from time B to time A. That is what causality says.

If someone set you this they are pulling your leg. The dx is shown under the square root sign so it is not a properly constituted integral. Please check

Which is why I am suggesting also addressing the (first) posts of those that slip through the net.

Why not ? I would actually expect enhanced functionality, not reduced as has happened. What I actually see now is a big Google "Privacy and Security" notice overlaying just where i am trying desperately to type.