studiot

If a uniform field moves, then the actual values of say the electric field remain constant at any point. There is no uniform field in the vicinity of an electric charge. So if the electric charge moves the actual values of the field at any point vary, and the change of values moves along with the charge. This is therefore a propagating disturbance in the electric field. Which is another name for EM radiation. Equally if a nonuniform field moves then the value of the elctric field at any point is changing as the field moves. Which again is another name for EM radiation. Does this help?

This is true and I agree. For example, the ever so appealing ''theory'' of the holographic universe and life being an illusion. There is no possible way to prove or disprove this and it makes no difference in anything we do or learn. It is quite possibly not even possible to prove it or find how it impacts life. Therefore, it cannot be scientific, but it can be bad philosophy at best. Hmm, let me see if I can apply those principles. So the length of my garden is Philosophical until I take a tape measure and meaure it, then it becomes Scientific? But the length of the coastline of Britain (after Mandlebrot) is a definite fact that is measurable with a tape measure?

Yes I think it is a very slippery subject to which there is no one or right answer. This is why it needs to be taken in context and problems arise when the promoter does not supply sufficient context. I was just looking at my digital clock. What did I see? 12:01 or was it 12 01 or was it 1201 ? The colon is flashing, and not part of the time so my mental image is of the numbers only. Further processing from the eye has taken place. I am also used to tech drawings so when I see the standard three view layout I do not see a sheet of paper with lines, square, rectangles triangles etc on it. I see the 3D object they are depicting. But that skill only came with practice, it is developed not inherent.

Here is a start. The coordinates of a single event point are {x,y,z,t} in one observational coordinate frame and {x',y',z',t'} in another. The values of x',y' z' and t' in terms of x, y z and t are given in a linear transformation. Concentrating on time and considering that the t' frame is moving with velocity v parallel to the x (of the t frame) axis so we can drop the y and z t' = At + Bx; where A and B are constants So t' may be greater than, less than t or even negative depending on these constants. Constant B allows for the fact that observers in t and t' may start counting time from different zero event points. Introducing the relative velocity of the t and t' frames and doing some algebra leads us to A=1(1−v2c2)√=γ and B=−γvc2 So we have exchanged constants A and B for two others, gamma and c. Gamma is the Lorenz factor and is only valid for the combination of the two frames in question c is the speed of light and is valid for all frames. This is useful as these constants apply to the transformation of all four coordinates, not only time. None of these linear transformations lead to a 'dilation' of the coordinates. Noting that t and t' refer to the same event point we can answer the question what does dilate then? I said you need two (event) points for this. If we consider the difference between two points that is (x2 - x1) and (t2 - t1) in the first frame and (x'2 - x'1) and (t'2 - t'1) in the second frame We have a length and a time difference. Many physical quantities come in two flavours like this. Electric potential and potential difference both measured in volts Temperature and temperature difference both measured in degrees Each of the two flavours have the same units but somewhat different characteristics and are used for different purposes in physics. So back to relativity, these differences are taken between the same two event points (before we had one, now we have two points) but viewed in the different frames. So we are talking about the same length and the the same time difference in both cases. If you perform the Lorentz transformations on coordinates from one frame to yield the coordinates for both points in the other and take the length and time differences in each frame you will get different numbers. So observers in each frame will evaluate these differences as being different numbers. Alternatively if we substitute in the Lorenz transformations into my difference formula above (x2 - x1) and (t2 - t1) in the first frame and (x'2 - x'1) and (t'2 - t'1) in the second frame we will obtain formulae for what happens when we consider the same time difference or distance difference (length) from the standpoint of difference frames. In other words we will obtain the formulae called time dilation and length contraction. One final note These formulae are developed using linear or 'first order' analysis. This is OK when the event points are close to each other and in particular the differences can become infinitesimals. So ΔtandΔx become δtandδx This allows us to define, or assign meaning to, calculus operations involving relativity formulae.

The UK Dounreay reactor was the worlds first and only fully successful breeder reactor which operated from 1955 to 1977, until the UK government got cold feet. It supplied national grid power and added an huge boost to the local economy in a previously poor area. https://www.google.co.uk/search?q=History+of+Dounreay+reactor&ie=utf-8&oe=utf-8&client=firefox-b&gfe_rd=cr&dcr=0&ei=SaFtWvLTE7TP8AfMmovIAw I remember at school being taught how the availability of cheap electricity enabled the aluminium smelting industry to develop in Scotland, but that's also gone now. And thanks to OldChemE for sharing his knowledge of the subject, including facts I didn't know. +1

Good morning, Yuan. I'm glad to see you are now fully participating in the forum process. As regards my comments, they were not contradictions of your work. They were, just as I said, comments on the text. This means that I think something was not properly explained or defined at the point in the text I highlighted. Or that it seemed at odds with something you wrote at another part of the text. In fact at one point I think you have said the opposite of what you really mean. It does not mean convey my opinion on the subject, that would come later. I am trying to help you put your work into a coherent piece of English for presentation. Then we can consider the truth or otherwise of it. This is a normal process when someone writes a paper, as you have done. So let us put something straight to begin with. your title reads "The derivation of relativity from the twins paradox." But unless you accept relativity, the twins paradox does not arise. You have it the wrong way round. The twins paradox arise because we have observed relativity. So the twins paradox is derived from relativity.

I have now had enough of these insults, despite a properly curteous discussion between other members demonstrating that how this can be done. So I am reporting it.

My Chambers dictionary of Science and Technology has So they are clearly of the opinion that the formation of the image on the retina consititutes seeing, not the model constructed in the brain from that "sensation". Yet that sensation is no use without the collection and transmission of the signal to the brain - the owner of the ey is still blind without that.

Well I guess that anyone interviewing you for a job would know that you were not the discoverer that violet photons were different from red photons.

Here is another example. Ask a musician what she sees when she is sat at a piano, playing the music on a piece of paper in front of her.

Yes that is true and the OP gave us a specific size and shape for the thing so it has a particular resistance. To investigate the effect of varying that (plate) size, standard tables of thermal resistance are available for different sized plates, based on actual measurements.

Well spotted +1

Actually that is contained in the electrical engineer's version of themal resistance I mentioned, as is the emissivity of the surface and other (heat) transport parameters.

Sensei, koti is building a flashlight (torch). Even LED light sources are less than 50% efficient at conversion. The rest of the energy is dissipated as heat.

An interesting summary view and well worth considering (which I am doing at the moment). Thank you MigL +1

A heat sink the size of a football pitch composed of the highest possible thermal conductivity would be of no help if you can't get the heat into it. This is the same as saying that connecting a 6 foot diameter pipe to the end of my hosepipe will not get me any more water through if the faucet is turned right down.

No I'm sorry I didn't make myself properly clear. Nature confines an electron within an atom by creating the atomic proton/electron/neutron structure. IBM created an entirely different confine using electrical forces.

Let me dispute that claim. When I look at a bowl of fruit, the model created in my brain is indeed a picture of a bowl of fuit. But When I read a book the model in my brain is not of letters printed on a piece of paper. If that page of the book is about a bowl of fruit then the model is again a bowl of fruit. But if the book is about abstract mathematics, what do you think the model is about ie what sort of 'picture' do you think it creates?

Earlier today I responded to a thread about differential equations in homework. But it seems to have disappeared. Can anyone say what happened to it please?

A few years ago the IBM research centre reported what journalists called 'designer atoms'. What they had managed to achieve was a potential well 'corral' for electrons by ultramicro printing techniqueson a silicon chip. I seem to remember this was using a force-ion microscope. Sorry I can't remember a better citation

I'm sorry I don't know enough about the detail for the mechanism of colour blindness or people with mixed up senses to comment. Is seeing something of zero-size logical? I'm sorry I fail to the the connection to anything I have said. What has zero size and is it visible or invisible?

I said it was not a subfield. You have not yet established that it is or even offered anysupporting evidence, as I did for my counterclaim. One of many answers to that question is "the determination of the exact ratio of charge to mass for the electron" Why did you not give Science as well as Philosophy a capital letter? Do you have a down on Science? Why did you not also ask what areas of Philosophy are not addressed by Science? I might respond "The reason why I don't like mayonnaise on my chips but you perhaps do".

Up to about 400 years ago I would have agreed with that statement, but since that time there has been a divergence between the two. The point is for something to be some sort of subdivision of another implies that it is wholly contained within the other. But there are aspects of Philosophy not addressed by Science and There are aspects of Science not addressed in Pholosophy I seem to remember posting a Venn diagram to a similar question about Logic, Maths and Philosophy a while back. Can anyone remember this thread?

But you don't seem to be saying anything ? I'm sorry to hear of your water shortage in Cape Town, is that the reason for your lack of loquacity? But since someone likes my model, I will press on to address the actual OP about visibility v invisibility. My first post here, but now residing in the spin off thread, I indicated that the situation is more complicated that at first meets the eye (pun intended). This complexity extends to the question of visible v invisible and occurs, regardless of where we conside the seat of vision to lie. Consider this One of the standard tests for colour blindness consists of a series of pictures made from dots of two colours, with a field of dots of one colour containting an embedded symbol of dots in the other colour. In the series the colours approach each other until the symbol is 'invisible' to all humans. In the more contrasting earlier pictures the symbols are visible to some humnans but not others. Yet all humans receive all the light reflected off all the dots.

I'm listening ?