geordief

Well the first civil war as it affected the Canadian colonies then is described here (a bit of a syopsis) https://thecanadianencyclopedia.ca/en/article/american-civil-war It feels like ,if there is a second civil war in the States that Canada may not have the option of remaining neutral based on that precedent.. Interesting that there were sympathies in the colonies with the Confederates even though more "Canadians" fought for the North. (all new to me.I wish it didn't seem relevant) From the link apparently Ulysses S Grant was sympathetic to Manifest Destiny which laid claim to Canada.

I don't remember the thought that made me wonder this but it is the physicality of the situation that interested me. When the mind makes a "mistake" is there some kind of a mechanism that "misfires" and that vould ,in throry be shown to have so done? To my regret ,I was once asked ,in the interview to a university philosophy course what woild qualify as a wrong action and I replied that it depended on what the actor thought themselves (ie some kind of moral relativism) The follow up question was "Was Hitler right?" and I answered yes(obviously i disagreed with him but thought that he may have been "right on his own terms" Looking back,I was trying to impress in the interview -and I think I succeeded .I suspect some of them may have thought i did not go far enough. As regards the OP it seems to me that the "mechanism" that might ensure a "correct" perception just does not exist and I wonder if any consequences might flow from that. After all it seems to me that one of the main aims of a good life should be to correctly perceive the world /to look the world in the face and this might seem to undercut that effort. There is the third option of "I don't know" but do we only have that thought after the perception whilst our "instant" thought is to jump to one conclusion over the other Do we always "second guess" in practice? Is sometimes "second guessing" all we do and do our instant perceptions just take place in our subvoncious mind?

You walk down the road and mistake a flash in a dark corner as a knife and walk into the road to be run over by a car. Or you see the flash and do not mistake it for a knife and carry on walking. Are those 2 classes of thought ("wrong" and ""corrrct") or is that just a post factum categorization ? Is there any way ,even in theory by examining the physical structure of the brain and body that it could be possible to gauge whether or not the physicality of a thought lies in either category? Or is this just a question that can be asked but never answered other than to examine the consequences that flowed ? (and even then different observers will have different interpretations -if the person in the scenario was on their way to commit mass murder for example)

Venezuela,surely? Yes a fine passage,though. Always the ways with imperiums.It is how they print their passports

We will prevail with our "sens du drôle" !

"Verifying that you are human.This may take a few seconds" Scienceforums.net

Shame it doesn't work ,then.

I suppose swansont is a "slipperyian".

When it comes to predicting physical outcomes in our(classical) universe is the spacetime interval the only tool that can be usefully so used? I also wonder whether there are other higher dimensional spaces (called Hilbert spaces?) that I suspect may be used to model other phenomena. If that is the case are there comparable tools for measuring distances in those spaces and would you be able to give me an example (or do they all just use the simple pythagorean system with extra dimensions?) Btw do any of those higher dimensional spaces include a time axis that works in the same (imaginary?) way as in Minkowski space? @MigL didn't see your post. Yes,angular distance seems like another way of doing things(does that work in spacetime?). Would that just be the same as polar coordinates,really?

Is the question here whether a particular system can be considered as having a measurable property in that it contains(spacetime) intervals? (trying to keep up with my own assertions) Well ,those intervals could be evenly spaces (flat space?) or unevenly spaced in regions of the system that contain varying energy densities . Could that system have a measurable property based on the intervals between its events? As an aside is the spacetime interval also called or closely related to the metric?(have heard "metric" used very often with understanding it too well)

Are you saying that events have to be within the "causal window" to be related?** Might my post stand up if i limited the events to that subset? Or would you stilll answer that there was no intrinsic system of events ,but just that we put that construction on them? **perhaps it was a more general observation?

A property of the system? Is the system as (physically) real as the objects (events?) that populate it?

I thought the particular spacetime interval was definitely real whether or not we agree upon it in different accelerated frames or not (I was under the impression that they did agree but perhaps I was mistaken and the agreement only applies between unaccelerated frames I also thought it was possible for an observer X in a frame accelerated wrt observer Y to calculate the spacetime interval as observed by Y if the observations were indeed different. (Perhaps I am mistaken in this also :-( In any event I have been under the (mistaken?) impression these last 10/15 years that the spacetime interval was the one physical quantity that all observers could agree upon.

I think I mean real as in that they exist (not necessarily physically -but possibly physically and at least as a property of something which is physical) Not quite sure what you are asking in your second paragraph but does it boil down to asking ehether what I see as real is equally as real as what you see as real even if we disagree as to what we are seeing? If that is the nub of what are asking then that is a difficult question and perhaps I might say that we would have to look for the intersection of my perception of events and your perception of events and that this intersection would include everything that we can agree on (like perhaps the spacetime interval and perhaps other quantities I am unfamiliar with) That sounds a very limited area of shared realities but perhaps it is a building block and once we know it is there we are free to gaily constuct cities in the sky of assumed realities that are probably true and most usefully so. The alternative of imagining that things aren't real because we can't prove it for definite is too miserable an idea to hold in the head (I am not sure if anyone does-I don't except in a fleeting ,whimsical way from time to time)

Is space time not just the set of intervals between events? If the events are real aren't the intervals a property of those events? Aren't properties as real as the objects themselves?(the events) If the events follow quantum rules then would quantum spacetime reflect the behaviour of the quantum objects?

Was I wrong (or is it irrelevant) to see flat spacetime as a kind of curved spacetime? "Flat spacetime" just being an idealized limit of spacetime which is always curved to one degree or another?

Can't one measure a spacetime interval with two beams of light directed from an observer at two different events? (eg moon rise and moon set)

You would be John Lennon?

...dixit dipstick

Life was simpler back then.They never had to divide by zero.

I don't know.

Still working through your (and @MigL 's ) earlier replies but I just wonder if the "universe creating space as it expands" concept covers this?

I wonder do any physicists use the term "vacuum" in that "old" sense nowadays? It is used ,but as you say I would like to know what it is meant to mean specifically. (Or whether it is perhaps just a portemanteau for something we don't /can't understand whereas we do have models for things pertaining to the old idea) When you suck as much the energy out of a system as possible do you approach one universal configuration or do more than one such configurations open up?

Is that not just a definition for a "vacuum"? (a vacuum as otherwise defined** may not exist by its own definition) **"absence of anything"

Yes,that result is set in stone.The rest of the world will have to put down the tinted spectacles when it comes to dealing with America,whatever comes next. In addition the whole world is changing at an accelerating pace and America will no more keep abreast than any of us. I remember a conversation back in the 60's where I was talking to a friend who happened to be one of the visible disruptors in the local Gilberd school( I was friendly with the son of the headmaster who was really cheesed off about it/him-thought he was a middle class poser) Anyway his words to me were that he would like to destroy the system and "see where the cards fall" (I assumed he was an anarchist) I don't suppose he espouses that view now but these are the times he was wishing for back then.