geordief

I use acetone to thin fibreglass resin so as to strengthen wood in rotten wooden window frames. Thinning the resin allows it to soak in further (you have to add hardener as well ,of course). I actually use nail polish remover as I can't get pure acetone from the chemist but there is some acetone in it -although some kinds are described as acetone free.(which I try not to buy)

Not quite sure what I was thinking . I wasn't sure that the CoG would stay the same as I was imagining the circumference of the wheel transforming into a non spherical shape . Thanks.

Is the original circle elongated in the direction of the original rotation? (an ellipsoid?) What about from the two frames of reference , the evolving c.o.g ** of the system and the original one? Do they differ? ** centre of gravity

thanks.

I was ruminating on time dilation caused by acceleration/gravity and this scenario came to my mind. As I was unable to work out what would happen , I asked for help. The "spokes" turn into nautilus like shaped spirals,don't they?

Are there any implications from Cherenkov radiation that could have a bearing on the subject of potential faster than light- in- a- vacuum speeds?

That is all behind us now (bar a second coming) http://www.independent.co.uk/news/uk/home-news/fish-and-chips-squid-cod-haddock-global-warming-warmer-seawater-chip-shops-a7469836.html

As you sow.... It is well reported that Christianity (not just Christianity ,of course) usurped these old festivals to embed itself in new cultures. Now they are getting a taste of their own medicine. I have a suspicion that more "religious" Christians may set greater store on festivals like Easter as they see what they may view as the commercialization of Christmas.

"You don't want no pie in the sky when you die, You want something here on the ground while you're still around." http://www.azquotes.com/quote/823350 "

Thanks(I suppose ). That seems so far beyond what I have begun to come to terms with that I will treat it as a long term project. I will keep an ear to the ground and perhaps I may worm a way into the subject eventually.A direct approach would be sure to fail in my case. Still ,thanks for the "The tangents do not exist in the same universe as we do." warning. That is probably one less stumbling block and source of grievance for me now

Thanks. I will. That was not new material for me (the Elementary Geometry extract) but I think I have now overcome a road block in my mind since I have realized that it is possible to calculate angles without leaving the surface of the globe . If seems possible to measure angles simply by measuring and comparing lengths of lines . I had only(well practically exclusively) looked at angles in a visual way up till now. I am now comfortable with the notion that it is possible to gauge curvature of a surface in this intrinsic way. I am not sure how this is accomplished practically in 3d+1 geometry but I guess the theory is no longer so mysterious and probably the corresponding distances are spacetime distances? I am still a bit unsure ,mind you about this idea of tangents to the curvature. Does that not require an extra (embedding) dimension? Or is it simply a mathematical device of some kind?

I have heard that intrinsic curvature does not require a manifold (is that the correct term?) to be embedded in another dimension for its curvature to be apparent ( and calculable ) to an observer inhabitant. Parallel Transport on a globe is adduced as an example whereby a dweller on the surface can test for intrinsic curvature. How can this be the case if as is described the vector which is being transported lies in the "tangent plane". ? Does this tangent plane not lie in a higher dimension ? How is it possible to have a tangent plane on the surface of a globe that does not presupppose the existence of an embedding 3rd dimension? To carry on the idea (to an area I am extremely unfamiliar with) are there not supposed to be corresponding tangent planes in 3D+1 spacetime (tensors?) ? Do not these tensors also presuppose a tangent plane which is situated in an embedding dimension (so a 5th dimension)? To go back to my parallel transport on the globe ,is it really possible for a 2D inhabitant to calculate its curvature without recourse to a "bird's eye" view? I mean ,how can he measure the angles of triangles for instance without looking down at the triangle he has drawn from above (which presupposes a 3rd dimension) ?

Is it known why Einstein came up with the idea of curving the co ordinate system ? Was it a shot in the dark? I mean nobody knows why mass-energy does this.Did he perhaps just notice all the curvature effects that show up in acceleration and treat the effects of gravitation in a similar way? Was he already aware of deficiencies in Newtonian physics so that he had tests in mind whereby he could verify whether his model was more accurate?

Suppose there is a wheel that is revolving upon its axis and we imagine that it is made up of very many electro magnets(like a leggo construction). Its shape is that of a conventional wheel with perhaps 20 spokes and a circumference -all made out of the same material , these very small electro magnets which are all the same size and shape so far as is possible. As the wheel turns it maintains its shape , held together by the magnetic force between its components. What happens when the electricity is cut ? I am wondering what shape the wheel adopts as it starts to disintegrate? Do the spokes arc in the direction of the previous (before the power was cut) revolution or is it the other way round? Do they also elongate (as I imagine they do? Might there be an animation somewhere that shows what happens(or something similar) ? If this wheel is removed from gravitational sources , does its own distributed mass have a bearing if the speed of revolution is not too great?

We have no idea what the total mass of the Universe was around the time of the Big Bang? And what the total mass of the Observable Universe is "now" ?

Is there any indication as to what ratio there may be between the size of the Universe that we cannot observe and the size of the Universe that we can actually observe if we assume that this Unobservable Universe was present at the Big Bang?

Is it possible that the expansion at around the time of the Big Bang was fueled by an outside source ? Might there have been ,for example fields emanating from outside the OU that intersected?

That is the Observable Universe,is it not? Is there a claim that the Unobservable Universe was also ,by inference gathered into a small area? Is it not rather that some of the Unobservable Universe (without knowing how much**) was so gathered? By the way is the Universe at around the time of the Big Bang considered to be finite in size in its own terms or just from our present perspective ? **perhaps all of it ?

Are there any theories that posit the universe as being finite and bounded? What implications might there be?

That is new to me. You do know that is not how the expression is normally used over this side of the water? That also occurred to me. Is this "centre of the universe is everywhere" idea predicated on the universe being infinite?

Can we infer (not just guess or extrapolate) what conditions are like beyond what we can directly observe? Are there observations we can make that lead us to make assessments about that which we cannot observe? Can this be made circular so that we could make predictions about what we can observe based on those inferences? EDIT: "carrot and stick" ? You don't mean "catch 22" ,do you?

If the (observable?) universe as a whole has positive curvature would your sphere also exhibit curvature features? Would its radius (admittedly unmeasurably?) fail to fulfill the Euclidean ratio between its radius and its surface area?

A bit cheeky? Or are we all at the end points of a network centred on a server(s) running the OSF? ..unless we are offline.

This is ,I guess a mathematical object. Are there any physical phenomena it can be used to predict.? Like others,I see it as representing 4 dimensions plus time. It is simply a mathematical curiosity or can it model any physical and observable process that occurs? Perhaps the idea is that it may model some processes that call for a larger number of dimensions in some quantum gravity theories? Correct me if I am wrong but this (tesseract) is not something that can be actually manufactured physically as the "physical object" would collide with and pass through itself.

Is this the kind of thing? "Trump pledges 'consequences' for firms moving offshore after $7 million tax deal with Carrier" http://www.chicagotribune.com/business/ct-trump-carrier-jobs-subsidies-20161201-story.html Short term "benefit" which allows him to make it look as if he is doing something? This will have no substantial impact on keeping jobs ** in America will it? **assuming that is a worthy aim in the first place.