geordief

Sorry ,no that is not what I meant by it. The agency responsible for things affecting one another would be fixed but the outcome would be variable as it would depend on distance as one example. Hope I am not waffling too much but I have this idea that there could be a "fastest possible" way that things could interact or impact on each other. With the universe as we know it this seems to be be closely related to light or em radiation. Could this relationship (if I have correctly -or even closely -identified it) be not set in stone?

Well tachyons are not theoretically impossible ,I believe. If they did exist our "universe" would be a subset of a wider universe whose laws we would be subject to but which might not affect us so that we would notice. They way you have described the situation would indeed apply** to this subset of this possible universe (which is only a theoretical possibility I agree and also possibly wrong) **I cannot personally say one way or the other on account of my lack of study but I have no reason to doubt you. By the way do you not like the phrase "speed of causality" as expressing the fastest possible speed that things can theoretically affect one another? Could it be formalized?

So is it possible to define the situation as the speed of light (and everything we know of) as being limited by the speed of causality or information (are they synonymous terms) rather than the other way round?

Does th Is it helpful /correct to regard light as the speed of causality(or information) across a vacuum .?

I think they are still in the process of explaining why this is but several surveys have apparently shown this to be surprisingly true. Presumably it may not apply equally across the board to the different classes of people based on age ,medical condition and so on. I am just an interested spectator and have no original input.

I am no expert but I think I heard recently that carbohydrates tend to be stored in the body as fat whilst the fat that you eat is burned straight away and also makes you feel full. When fat is eaten in conjunction with carbohydrates it seems we cannot stop eating it (our appetite stays strong) The latest advice seems to be that animal fat has a very clean bill of heath -and eating fat does not make you fat. To throw the cat in among the pigeons "they " are now saying that being a little obese may be healthy as those people tend to live longer.. Sorry I have no citations. and my understanding is in no way authoritative.

Thanks. And if, on the Minkowski map the new origin was at (t,x) =(T,X) do I just get the same scenario as it was from (t,x)=(0,0) except that now the signs are reversed and the first FoR is in the past -in the bottom left hand quadrant? Assuming ,of course that (T,X) are both positive.

Not to show that Swedish is "simpler" than English but this phrase from the OP shows how they work similarly (in my eyes) . "jag önskar bara engelska var så enkelt som svenska " seems to mean "I only wish English was as simple as Swedish" and I notice that the conjunction "that" is missing in both languages. In other words we do not need to say ""I only wish that English was as simple as Swedish" and neither do you need to do so in Swedish. In the Latin languages I am fairly sure you would need that conjunction and maybe also in German (I am guessing) . So that is a similarity I would notice. I cannot say how this rule works in other languages (I believe there are a few)

Suppose I am an observer and ,as such am situated at the [x,t]=[0,0] event point on a Minkowski chart. Now there is an event that occurs in my FoR at ,let's call it [X,T] (I have not worked out how to write mathematical equations here yet) I would like to reset the Frame of Reference to be from the point of view of (a new observer situated at) this new event which does not share an origin with the first observer's.How does this new FoR view the first observer's worldlines ?. Is that quite simple to do ? (the different observers are not necessarily stationary wrt one another) I have a second related question. Are there any alternative methods of graphically ordering the set of space time events or is the Minkowski graphs the only game in town? *I mean the worldlines of other bodies as seen by the first observer (including of course his own) -how does this new observer see them ? At a minimum how does the new observer see(on his spacetime graph ) the x=0,t=0 lines of the original observer? PS any links on the internet that address this question would be very helpful.

permettez- moi de rire (lol)

Although it is hard to talk about your own native language I believe it is well known that English is quite a complex language. I believe its vocabulary is high compared to other languages because it has assimilated so many foreign words. I have also heard that there are lots of "exceptions" to the way words are actually pronounced vis a vis how you would expect them to sound based on their spelling. The corollary to this is that other languages are likely to be simpler and more predictable -once you learn the basic rules there are probably fewer surprises down the line. I did learn to speak Norwegian which is quite close to Swedish of course. What I noticed at the time was that the order of words was rather similar to the order of words in English -which was a pleasant change from the Latin languages like French ,Italian and Spanish where words seemed to need to go "back to front". I always felt that Norwegian and English were very close linguistically . Apparently it is the language spoken in Friesland which is supposedly the closest . I think Friesland is an island in The North Sea belonging to Holland whose population migrated to Britain and brought their language over with them.

Thanks, I am happy now.

True, I misspoke.. I was trying to get across the idea that one measurement can serve to measure 2 things . The distance traveled by the light in the light clock can be said to be identical in theory to the distance traveled by the light in the laser traveling to the target and back to the receiver next to the light clock. I was trying to make that point because I think it was actually the first time I had specifically realised it was the case and I was hoping to get corroboration that it was in fact true. If we measure the time elapsed I think we are in fact measuring the distance traveled by a ray of light in the light clock and if a beam of light is simultaneously sent to and reflected back from a target then the distance traveled by both rays of light will (in a vacuum) be as numerically identical as it is possible for them to be.

(been gathering my thoughts) The 8 measurements were (overcautiously perhaps, but hopefully not wrongly) including 4 implied measurements[0,0,0,0,] at the start (origin) of the experiment... Anyway,have I understood it correctly now that the distance r (to the target) you have mentioned is exactly numerically identical to the distance (ct) measured by a light clock apparatus provided that r is separated from the origin by a vacuum and it is targeted with a laser traveling from the origin at the speed,c? So one measurement of the time can simultaneously measure both the distance to the target and the lapse of time with 100% accuracy (if we take time here as simply a measurement of the distance traveled by the light in the clock) PS : If I want to make a spacetime measurement between 2 events I simply take 2 separate measurements on the same clock and apply the normal spacetime distance formula ds^2= dr^2-d[ct]^2 ? (perhaps the sign is reversed)

If the target is not stationary. is it possible to take these 4 measurements together ? Does the target need to be extremely close to the origin/observer for this to be possible? Does it have to be specified that the measurement at the origin [0,0,0,0] must also be done successfully? Is the result of those 8 measurements still an approximation to whatever degree of precision the setup allows? Hope I am not waffling........

Is it possible to have the 4 measurements taken at the "same time" or is that an a priori impossiblity and something that has to be adjusted* for? Unless distances are very small the extremities ** of the physical metre sticks will be "wobbly" .Can't the measurements taken that way only be approximate? * do we just choose our level of precision/approximation? ** not just the extremities but it is the extremities that "make the measurement"

If we are an observer at the origin of a possible set of events ,what are the actual empirical methods of taking measurements to give a numerical value to an event that occurs subsequently? I am situated at ,say Jodrell Bank at the point in spacetime [0,0,0,0,] and there is an event that we can say is located at [x,y,z,ct]. How do I empirically and repeatably* make those 4 measurements? I have no problem (I hope) with the "ct" measurement but how ,in practice would I make the spacial measurements? Can I bounce a beam of light off them if the system is set up to do that? Are there any other ways to do it? *obviously not repeatably for the same event although perhaps the same event could be measured by countless different observers.

That is the first time I have come across the expression "the speed of gravity" . I am aware that there is a speed to the propagation of gravitational waves (c of course); Is that the speed to which you were referring?

The concept is apparently flawed and the notion of a force acting at a distance seems to have been distrusted well before General Relativity was formulated but it seems conceivable to me* that without the stupendous advances in technology since then that GR might still be a niche subject since Newtonian gravity did the job so well in the main. So what is it about Newtonian gravity that works so well ? Is it a bit like the difference between Special Relativity and Euclidean geometry: is Newtonian Gravity something of a "special case" of General Relativity? As an afterthought and to acknowledge the weakness of my mathematical skills it is not possible is it that ,if we replace the distance "r squared" in Newtonian Gravity with the "s squared" ** of Special Relativity that we can "tweak" Newtonian Gravity to be something that little bit more accurate ,is it? * obviously I could be way off in my estimate ** I mean of course using the "distance " between spacetime events as calculated in the formula s^2 =x^2 +y^2 +z^2 -(ct)^2

Christ I don't know. It was just a vague idea. If no one else can see any potential then I guess there is none. I was actually "thinking" along the lines of what is referred to as quantum computing but without any expertise my contribution has no value.

In fantasy land* could changes in a gravitational field conceivably be used in connection with quantum effects? *being charitable in my direction

But this disk is supposed to be a projected model of the set of 4-d spacetime events onto a plane ,isn't it? If so can this set of events also be projected onto a 3 -dimensional space? I am happy with the way the origin can be offset to any particular event. I am guessing that the event that represents the "Big Bang" singularity cannot be represented ......

I believe this is a projection of the tiling of a hyperboloid onto an x,y plane. Although this is far beyond my level of understanding , I have a question as to whether it is possible to use these Poincaré disk models in the plane to build a 3-dimensional model by perhaps rotating the disk /planearound one of its axes? If this is possible can this be seen as a projection of 4-D spacetime onto a solid,3-D "globe of the world* type" ball ? Can this be seen as a possible representation of the universe in a purely special relativistic way (without accounting for mass or energy) - kind of like a blank page? This is a link ,although I imagine it is obvious what I am referring to: https://en.wikipedia.org/wiki/Poincar%C3%A9_disk_model * this kind of thing http://www.toysrus.com/buy/globes-telescopes/edu-science-world-globe-12-inch-diameter-globemaster-30524-2303946 although it would be transparent and the 3-D tiling would be visible into its interior.

Is this whole religious thing just one big red herring? Is the more fundamental point to make that our human values can be seen as distinct from scientific knowledge? I am not saying that they can fly in the face of scientific knowledge but we do ,in my opinion face a question of whether to give free rein to researchers who can change our lives for good or ill -but most definitely for uncertainty -in an alarmingly short period of time. I appreciate the argument that we are now dependent upon scientific research simply to keep up with the growth of population ( and expectations) on this small planet On the one hand science is a just a (hopefully truthful) tool but on the other it has us running to keep up.

I don't disagree. I used the word "arguably" simply (and perhaps misleadingly ) to reflect the point of view of other people who seem to feel that. I can't really give my own point of view ,save to say that it is not a feeling that I have ever had personally and have only encountered its expression via other people I may also have confused(or wrongly interpreted) other peoples' life crises with a more cosmic "what's the point of it all" complaint .......