studiot

Back to the OP First off TakenItSeriously (please get a shorter handle) I am going to say +1 for encouragement. Iam am impressed by the reasoning of your case, this is best chain of reasoning I have seen you present. But you should beware avoiding mathematics because the best of reasoning is useless if founded on shaky premises. It is possible to reach the wrong conclusion from them or it is possible for two (or heaven forbid more) errors to 'cancel out', thus reaching the right conclusion for the wrong reasons. Looking at your statements of symmetry, the difficulty is that the symmetry of the Physics relies on a common variable. That is the symmetry is in the the same variable (one variable) in both aspects. The common variable in this case is the relative velocity. You have taken time from one twin's frame and compared it with time from the other twin's frame. So you are comparing two different situations. The actual symmetry works like this: Twin A sees twin B receeding at 0.8c Twin B sees twin A receeding at 0.8c You have, however correctly identified that what happens to the rest of the universe is the basis of the logical resolution of the paradox. Note that the travelling twin (B) has no means of measuring the distance to his destination, once he has set off.

Thanks for the cooperation. +1 I think science sites work best that way.

The elevation difference would only have a significant effect if the higher level placed the panels clear of some (partial) shading object such as another building or trees etc.

A BBC report about the the Toba volcanic eruption that sheds new light on the human response during the winter that must have followed and its effect on human evolution. This appears to run contra to previous ( conventional) thinking http://www.bbc.co.uk/news/science-environment-43377960

What a wonderfully clear explanation, HI. thank you +1 Hashtag, I didn't know they did NMR at A level these days, but welcome and bring on your questions.

You have asked for comments on the paper. Reading it I have some difficulty discerning exactly what it is you are interpreting. You should certainly spell this out at the beginning. Your comparison of Classical v Quantum including when to use which only covers cases selected to support your case. Other situations and considerations dshould be visited/included. For example the QM solution for the translational energy of an isolated molecule in a rectangular box a x b x c is [math]{\varepsilon _{translation}} = \frac{{{h^2}}}{{8M}}\left[ {{{\left( {\frac{{{n_x}}}{a}} \right)}^2} + {{\left( {\frac{{{n_y}}}{b}} \right)}^2} + {{\left( {\frac{{{n_z}}}{c}} \right)}^2}} \right][/math] Where n is restricted to integer values. which is much more complicated than the classical version [math]{\varepsilon _{translation}} = \frac{{M{v^2}}}{2}[/math] Furthermore there are a very large number of very closely spaced levels in the QM solution, clustered around the classical value. So simplicity suggests the classical calculation wins hands down.

So you show utter contempt for others and their views. I did indeed make the post you quoted whereby having explained my suggestion I asked just one question. Was that contemptuous spiel a response to my question, or are you avoiding it? Strange I agree, +1

Do you always respond with a barrage of personally directed invective?

But that view is seriously inadequate as it only describes part of the situation. Hence the impasse.

Strictly speaking that is true since the original question was Is light visible or invisible ? When this question is applied to anything whatsoever it means Is that thing capable of being seen or not capable of being seen? Now although these two qualities are mutually exclusive and complementary they also possess a fundamental difference. If something is capable of being seen it does not matter whether or not it is actually seen. That is it does not matter if there is something or someone there to perform the seeing activity. Nor does it matter if the physical agency by which the seeing activity is performed is present or not. All that matter is that if both those conditions are met then seeing could happen. So, for instance, to see an object that is in the dark all we need to do may be to switch on the light. But we may also need to satisfy further conditions. In those circumstances, what colour we see is irrelevant we either see or we don't. On the other hand if something has the quality that it is incapable of being seen then there is nothing we can do to the conditions or the object to see it. That is the definition of the word incapable (or invisible). Having said that, the OP is long gone and many have a clear desire to widen the discussion, something the mods permit in such circumstances. So the question then arises, can we put together a coherent and rational model compatible with all the expressed conflicting views? My answer is yes such a model is possible, although it might suprise some.

I'm sorry someone was not impressed with this post so let's lay the underlying misconception to rest. You can no more say that light has no colour than you can say that a bowl of water has no temperature. In each case a part of your body can be used to estimate the physical quantities we use to measure these properties and in each case these days we have more accurate and sensitive machines to also perform this task.

Only in very specific lighting and observation conditions. Equally it can be done only in some parts of the spectrum, but to follow string junky's line in others they cannot. Orange in particular lies in this zone. This discussion has become polarised into two camps. Those who insist that the retinal image is not seeing but the brain model is, and those who hold the reverse. I really can't see why we can't all agree that seeing is a general term that can be and is widely used to denote either or both of these. From this the logical action is to use new terms, (detect and perceive are as good as any) when we need to make the distinction clear. However I have also just shown where see has yet another meaning (understand). Perhaps there are more still?

So how does this help our discussion?

I think you are the only person who agrees this.

So you are saying that the system in the human eye can distinguish between two waves one of 540 nm and one of 541nm ?

Yea, +1 Good to point out there are more than one interpretation of many phenomena.

Thank you for that clarification, did you not want to discuss the mechanism of the effect you posted about, whoever saw it? I thought it was an interesting contribution.

True but incomplete. Please not my comments a few posts back about the actual sensors splitting the incoming light into 3 bands.

I would suggest that the reason for your experience is that the strength of the reflected red light is actually quite small compared to the strength of the light coming through the window so this dominates/overrides the red in bulk. But when you cut the receiving area down that balance changes in favour of the red. Please note this is entirely consistent with furyan5's link, which I will repeat here as it offers an simple explanation of the mixing of colours. https://kids.frontiersin.org/article/10.3389/frym.2013.00010

Yes our eyes detect, but furyan5's link is right that colour is a mixture of many wavelengths. Further the link explains how the detectors don't detect wavelengths as single wavelength, but as part of a range. The part of the EMS you mention is split into three for this purpose in most people.

Magnanimous of you. How is that supposed to work?

If you can only respond to one point at a time why do you post multiple points in your posts.? one question. I'm sorry I can't respond to your second point (as requested) in your last post until we finish this one.

I did read the article and I liked it better than I thought I would. Would you like me to extract and display the exact passage that conflicts with your absolute declaration that a colour corresponds to a single wavelength? Don't patronise me, they were correct, you were wrong. Please also answer my other questions/points.

A pity this conflicts with the' high school' explanation you posted a link to. You also needed to introduce several new undefined words to offer your explanation. sensation, detect, perceive. Why are these better than Eise's see1 and see2? There is also a logical difficulty with placing all the meaning of vision in the brain. That is a non defective eye can only create a faithful retinal image of the received light with nothing added or taken away. The brain both adds and subtract extraneous material to the image it creates. I don't understand what you mean by reflecting orange light in all directions Please explain.

As I understand the use of Fourier transforms in the Loran system it is not to directly establish the position, but to perform a spectral analysis on the received signal to remove error producing changes. A modern development is to use the loran chain as a sort of radar, whereby the low intensity reflected signal is Fourier processed to separate it from the main transmitted one (which is discarded). However both uses rely on the positions of the transmitting chain to be known in relation to some pre existing grid. Demoguy you original post seems to be asking if you can generate some sort of absolute coordinate system, in defiance of relativity. I hope this is not the case.