geordief

Interesting question. Are "unreal" things "parasitic" on real things?(castles in the mind). If you have a group of real things they can be mentally arranged in quickly infinite ways and the arrangements are all unreal (maps without any territories for the most part) So real things differ from unreal things by virtue of being "undiluted" with too much sensory rationalization? A question of degree . everything has to be initially experienced sensorily. Makes no sense to talk of a anything real without someone or something to interact with it Just a stab...

Simply reproducibilty? So no "one off" test can show anything is "real" .It is all a building up of certitude? A balance of probabilities. Because what we call everyday reality is lifelong we confuse that with 100% certainty?

Are there any ways measurements can be performed without using EM? EM did not exist did it ,in the early stages.? So are there any measurements that can be performed under those conditions? No measurements = no dimensions?

That seems very interesting. So before EM got going there were other ways the universe "talked " to itself? Imbalances or asymmetries of any kind perhaps that redressed themselves? I have never heard that expression " a dimension is a variable" before (although I may have thought along those lines). Would that be a mathematical concept that may or may not have "physical applications" in the very early universe ? Am I talking rubbish again?

Does that make any difference to the way one thinks about quantum theory -that it may be instrumental to the very genesis of the universe we are living in ? Does it give it some kind of hierarchical seniority over GR because it was there before ("before" ?) GR came into play. Might GR be explained via quantum theory but not vice versa?

Never in this quite extraordinary context (not that I would be on top of it in any context but that is just the level I am at)

I will have to give it (and you) a rest and hope that your answers have been helpful to others more able than myself to profit from them. But just one last clarification. :these manifolds ,they are 4D spacetime manifolds are they ?

So each fibre is like a 4ply rope? Some are long and some are short?

This seems a bit weird. We have hypothetically an homogeneous state that is affected by a fluctuation. Can we ask if this fluctuation is exterior or interior to the state? (is it a question that it is actually permitted to ask or does it bring in or require spacetime which apparently does not exist in that circumstance?) Can it be integral to the state? How could this fluctuation destabilize the state? Is it rather that the fluctuation prevents the homogeneous state from ever establishing itself ?

OK ,thanks it was just a stab in the dark. But are they centred around an event in spacetime?

Is there a notion that at some point in the distant past the things we now see as distinct were actually "one thing".? I don't see how the transition from this state to a differentiated state might have been accomplished. If that state ever existed ,surely even an outside intervention could not have caused it to differentiate, So can we only be imagine a state that was extremely homogeneous but not in all respects? If there was a state of 100% homogeneity would that also imply or require pure symmetry also.(or would that even concept not apply)

@ ajb Are these fibre bundles infinitesimally small and can they be "stuck together" or perhaps "spliced" like a 4-stranded rope to give the larger picture? Are they like a 4D bicycle wheel with only 4 spokes centred at the local point in spacetime.? I am just trying to imagine this as a mathematical model. I don't think there is any connection between the universe expanding and things moving straightly along geodesics is there.? It would help the progress of my understanding if that was the case but I think I have learned that it is not true.

It would be interesting if it was indeed a quote that Trump knew came from Mussolini and had seen fit to bestow us with without mentioning "by the way this is from Mussolini but it is still a good quote" But I doubt we will ever know (or really wish to know ) how he latched onto this admittedly buffoonesque quote and so do not really have anything substantial to beat him with on this occasion. Smears can rebound.

Tommy Cooper. A brilliant performer who was able to do the magic and fluff it at the same time. Apparently a really unpleasant character in real life though.

Here is the quote from your post (which I have re read) "Just as he seems happy with the EM field is the 'medium' for EM waves" I didn't say I agreed that "the EM field is the 'medium' for EM waves" (not competent to say) . I just asked whether "by that definition" EM waves could be said to need 2 mediums. Not sure why you think I jumped to any conclusion. I thought it was a bizarre proposition but it seemed to follow from the premise you seemed to accord to Mike. Maybe you were being sarcastic and I took your suggestion too seriously ?

If I can party poop ,by that definition can the Gravitational Field also be seen as a medium for EM waves and so EM waves would have 2 mediums, the Gravitational Field as well as the EM field.? Is the EM Field "inside" the Gravitational Field somewhat in the manner of a Russian doll?

I am not sure if the Permittivity of the vacuum is relevant the the speed of light (or just hangs off from it) https://en.wikipedia.org/wiki/Vacuum_permittivity Are these electrical and magnetic constants "just" mathematical concepts or is there any circumstance where they might be different from what they seem to have been measured to be?

So absolutely everything is affected by gravity? And the gravity field extends the length and breadth of the known Universe,possibly being considered as the largest thing that exists? (it is continuous and entirely extensive with the possible exception of black holes ) Is it a kind of mirror image of the distributed mass/energy in the Universe?

Well that is supporting evidence for Trump being crude and ridiculous but we already know this and to use tendentious arguments against him may serve to strengthen his support. As was advised to Clinton do not get into the gutter with him as it is his preferred territory.

I would not wish to give any moral support to anything Trump says but the quote does seem reasonable in its normal context. The sheep are an analogy for a conquered people , I have always thought. So the Yanks shook off the Brits rather than opt for a quiet life. Many,doubtless of the Jews in Auschwitz would have given anything to avoid going like lambs to their end. It is a noble aspiration to fight against a superior (unjust) force even when it may seem hopeless. I recall the Italian who told his captors quite recently (in Iraq?) "This is how an Italian dies!" Of course a peaceable existence is also a noble aspiration but so can be the aspiration to "live one day as a lion" Trump is so full of it I doubt he has the generosity of spirit to entertain any real notion of sacrifice. but he is not unique in this regard.

Well I hope that is just an analogy..

Yes but GR only applies so far back . There is a "space " for a new model between the "singularity" and the point where GR becomes applicable, isn't there? I am not saying the singularity is a thing but there is a "space" where GR does not apply and that area of non applicability could be referred to as "before" -just not in a temporal sense.-more in the sense that it is an area (which looks to us from our vantage point like "before" ) which is perhaps something like a step change in "reverse". And you said the N Pole description was just an analogy. Prepared to admit I may not be making sense......

If this is an accepted scenario is there any notion of how there could have been a transition to a state where it was possible to conceive of temporal distances? This must go into quantum territory surely. Does it have anything to say? Does the concept of phase transition come into play? Is that idea bound up with "emergent properties" ? Sorry do you mean "sensible" in the sense of "reasonable" or "detectable"? I sometimes get confused as in French it has the latter meaning and I am no longer certain of its use in English in all circumstances....

Is there a notion of what time may or could have emerged from before(causally before?) it was /is the measurable quantity we now use? We say rightly or wrongly) in certain conditions we cannot speak of time but is there some other condition that allows the emergence of time? Is it an absolutely absurd notion that one day physicists will hold a news conference to announce that they have isolated a state where time does not exist and they are contemplating what tests it may be possible to probe this state with. At least could someone write a novel about it ?

Fool me once.... When will they ever learn? In fairness when Bush won by a whisker and the thing (as I recall went to the Supreme Court) it was easy to feel wronged. Hopefully there will be no repeat of that scenario. If I was religious I would be praying regularly for the conversion of the Trump deluded.