geordief

It is interesting to an observer whether this gap in communication can be bridged . This is almost like hostage negotiations. I am glad I am not in the front line

Plenty of new territory there. Thanks.

Thanks . It is very hard going for me. Maybe if I keep coming back to it bits of it will sink in.. hopefully the important bits Thanks also studiot for the "Geometry by Transformations" suggestion. I see it is quite reasonably priced on Amazon.

Fairly sure that is what Churchill did too. But I cannot find a link to back me up. I think the story goes that he told those around him that he had quit and so was unable to back track. Yes ,I thought that too. But maybe you need a long term strategy as well . Before I finally quit I had actually "given up" for 3 years straight only to relapse (for a shortish time) When I first started to smoke in my early teens I did tell myself that I would quit before I was 30 and so I had a motivation when the time come. But it was harder than I expected.

A very short term strategy but I had also thought about autohypnosis a possible (also short term) supplementary method.

Have you thought about taking up Lucid Dreaming ? It is fun and might provide another focus over the difficult period.

So if the Poincaré group is the set of transformations,what is the operator ** ? There are not different assigned operations for each class of transformation ,are there? If that is the case , how many types of transformation are there in Minkowski space and how many in Euclidean (that is the same as "Galilean" ,isn't it ?) space? Just a few? **so we could actually talk about sets of operators if it served a purpose......?

I sometimes buy tart cherry juice .It is supposed to help sleep (not that I have a problem) I doubt it would actually help you fall asleep any easier. Being tart there is not much of a temptation to drink too much as juices are bad in the main I would say. It is not cheap .(I don't think it contains very much sugar at all -none added anyway)

I stopped "cold turkey" on 5 or 6 occasions . Each time I stayed off it a bit longer and the last time (obviously) I never went back. Now I would be able to light a cigarette for someone else without worrying about trying a few extra puffs(it is actually a bit unpleasant at the very beginning anyway) The big temptation with me was if I was having a drink as the two went so nicely together -even now I only drink with a meal. As for your last thing at night ,you might consider having a sleeping tablet to hand on the nights when the craving is harder -hopefully you might only need to resort to that on a few occasions. It is a great feeling when you do get off them eventually . It is not an easy thing to do.

Thanks very much for that wtf. Actually I had made a little inroad into that territory (had opened those Wiki pages more than a few times) but it is great to have my initial understandings broadly confirmed . It is amazing ,actually what these earlier mathematicians were able to put together. They were the Olympic athletes of their day and even now it is hard to keep up with them despite all the scientific progress we have gone through since.

Yes thanks. I am fine with that.

I thought I had accepted MigL's correction in post#2 where he said: "Minkowsky space-time ( flat, ignoring gravity effects ) is not a group." You are not asking me to lay out and expand on my previous misconception ,surely? There was a cross-post between us when I replied to MigL in post #4 . Perhaps that threw you? I understand now that the elements in the Minkowski space are (acc MigL) "certain transformational operations ( isometries IIRC ) " This is now my point of departure for learning about the subject and I am at the beginning of that process.(I don't imagine vectors can any longer be (in my mind) a candidate for elements in the set in question) You are right and you did preface your statement with an "if". Even so ,it is a bit confusing to set up a condition that everyone in the thread agrees is wrong. In my opinion you should have made it clear that the statement following the "if" was incorrect to avoid potential misunderstandings. (I am open to correction,of course).

Do we need a "nod's as good as a wink to a blind bat " emoticon?

You should look at MigL's post#2 where he says "Minkowsky space-time ( flat, ignoring gravity effects ) is not a group" and goes on to elaborate. My initial assumption was apparently wrong.

Thanks. I will reset the satnav "La culture connaissance c'est comme le beurre, moins on en a plus on l'étale" It is Poincaré not Poincaire , MigL Crossposted with Studiot. Thanks ,as well. "commutative" was a missrecall. I knew it was "associative" but had a lapse.

I understand that Minkowski (Poincare?) Space is a Group in Group Theory.(am I right so far?) Well I have (re) learned that for a Group to be a Group there are one or two (4 ?) basic preconditions and that these are (1) that the set must have a operator and (2) must also include an identity element , (3) be commutative in the operations and that (4) each element must have an inverse. Oh and (5) it must exhibit "closure" How do these conditions apply to Minkowski Space? Are the elements of the set spacetime vectors? Are all the vectors unit lengths or can they be any length? What is the operation ? Is the set infinite? Have I got the wrong end of the stick somewhere?

Thanks ,ajb a lot of food for thought there. Actually you misread that reference of mine to Lorentz Transformations. I just gave it as the last in the list and the "cornerstone" referred to " the way moving frames are connected." I did indeed misplace an "and" in my list as I tagged on the Lorentz Transformation as an afterthought to the list I have edited it now.

After reading around the subjects of Special and General relativity (with admittedly patchy results) for quite a few years now, I have begun to tell myself that perhaps the most important result in Relativity might be the first : the way moving frames are connected. Never mind the speed of light , the lack of need for an ether , the equivalence or not between gravity and acceleration as well as the Lorentz Transformation perhaps it is this simple correlation (the way moving frames are connected.) that is the cornerstone of Relativity? I have seen the geometric illustration of this as it comes at the very beginning of the subject and is easily learnable by school children (which is a bit embarrassing on my account that I struggled (ad still do) with it so long) The most obvious point seems to be that the speeds (and all dependent relationships) in moving frames do not add up linearly. Have there been any other explanations of this really fundamental finding other than the way it is treated in Special Relativity? I mean the treatment of it in geometric terms is all I have really seen and I must have spent hours and days (years ago now) puzzling out which part of the triangle applied to light and which applied to forward motion. It all seems so cut and dried . Has there been discussion as to why it was deemed necessary to go down this (obviously now correct) road? Did it require the invariance of the speed of light in all reference frames to give the impetus to even consider the question? Were there no premonitions that moving frames might not be connected in a linear ,additive way? Was Einstein really the first person to have any inkling that this might be a question at all?

So ,to use my terminology the "modeled" is not so much a thing as a set of events of differing properties? Can we talk of an event having a property? If not what do "Position, speed, acceleration, energy, momentum" describe? Relationships between events?

I realize this is not how you might frame the question but if I refer to spacetime as a model does the term (in that context) "the modeled" have any meaning (apart from a semantic one) ? Do we (can we) have a model without a "modeled"? Or do we have a "modeled" that bears no apparent or intuitive resemblance to the model save in that the model allows us to predict events in the said "modeled" ?

Is there anything to my pov that nothing actually "hits" anything . Everything takes place at a distance. Contact is never made when we say two objects "hit" each other. Does the putative "spacetime " ** that might be said to exist as what is modeled by the spacetime model need to be physically hit if the same can be said for what we would consider to be physical objects? I am not sure how coherent my argument is . Are gravitational waves considered to be physical objects? ** I would like to give it another name to distinguish it from the spacetime model. Could I call them "spacetime model " and "spacetime modeled" respectively . Or does this attempt to name what spacetime is modeling seem too close to "aether" ?

If it was two stars colliding would the analogy be perfect? Would those two stars create gravitational waves that could reasonably be considered to be "hitting spacetime (or rather whatever it is modeling) with something completely analogous to a hammer" ? Would those gravitational waves be theoretically detectable in the same way as those of the BBH?

So I can't think of it like two hands clapping or one hammer striking another anvil?

I haven't learned about frame dragging yet. That is what it was testing ,was it ?

Do you think the recent Binary Black Hole merger counts as "hitting space time (or rather whatever it is spacetime is modeling) with a hammer" ? It had a physical effect didn't it?