geordief

Showing off some new knowledge I was given recently , it seems that acceleration does not curve space-time -.Acceleration (as distinct from gravity) ,apparently can be modeled just using Special Relativity as only flat space-time is involved. If I have understood my lesson correctly of course.

Going ,with permission slightly off topic I heard recently (in relation to the recent Black Hole detection) that these BH s were not filled with matter but filled with spacetime (or a similar term). Does that sound like a scientific description of what is happening or was it just pop speak for the viewers?

It is in the philosophy section of http://www.thescienceforum.com/forum.php

It is a question of "laugh or cry". On another forum I visit there is a thread where some one is advocating that all predators should be prevented from predating prey. It is a similar mindset I feel and really beggars belief .

I accept that "peace of mind" can have different contexts. I don't accept noseyness being the main motivator here. Where it is , then I agree it should not be placated as I do place a(extremely) high value on privacy. Again perhaps we agree in that we both seem to be looking for a proportionality. I am hoping the court cases pending will prove enlightening as , in my opinion that is where some of the finest minds are to be found(certainly far finer than mine) .

I can't say (not competent) but I am not sure "peace of mind " is uppermost in my considerations. The terrain seems to be shifting all the time.

Has the industry designed software with the aim of preventing case by case "break ins"?(my suspicion without competence to answer) Can't they design a system that allows the security services/ court system to "break in " on a case by case basis? Is Apple et al trying to box the "privacy invaders" (for want of a better term) into a corner so that if they want restricted access in a particular instance ,they can counter by saying that is an "appalling vista" where everyone suddenly stands naked? Is this shadow boxing?(economic and political propaganda) Doesn't this case show up the situation into stark relief? Like you (I think) I think we need a middle way . It looks to me like Apple's way is "my way or the highway" (hope I am wrong)

You don't think that this case is "on a whim" do you? Has the FBI not had to go through a court order in this case ?( well I assume they must , I don't actually know). Then again , there could be pressing/emergency cases where the security forces might ( with my approval ) go ahead with the "search" and apply for the court order at the same time.

Does the right to privacy have to be 100% sacrosanct? Since when has that been the case? In what other area of life has the right to privacy been completely over riding? Have there not always been justifications for invasions of privacy in particular circumstances? And is this not the first time in human history where anyone could be confident that their (distant) communications have zero chance of being intercepted? I feel very at risk (not personally) knowing that this is now the case (if it is and there are not other . places along the chain of communication that the security forces can intercept messages).

So is it possible to show the effects of massive bodies using the Minkowski spacetime diagram? If the x- and the t -axes extend to a sufficient distance is it possible to place massive bodies at a particular (region of ) spacetime points and would that cause the (x(prime)=0:t(prime) =0) axes of anything in that region to be curved around them as seen from the perspective of an observer at another point on the map(esp. the origin)? I am not suggesting that any straightforward geometrical or mathematical (except by using a computer) calculations could be performed but can it be illustrative? What I am trying to describe with these axes is that ,instead of turning into the normal scissor shape with a centre on the x=ct line (as speed increases wrt the observer) that these new axes should be curved when in the vicinity of mass etc -whilst still keeping some of the basic "scissor shape" around the x=ct line.

I have got a reply from the "poster" now. He cannot recall the post and is very confident that he either did not say anything like that or that ,if he did it would not have been right. Possibly (he guesses) he may have said that it was possible to derive GR using SR as a starting point . But of course ,that would be if the post actually existed . I am still confident that the post exists and maybe I will track it down but that is just curiosity value for me (and the poster) now. I apologize for my poor recall and understanding in this case.

I will as soon a I can find it. The poster may remember it better than myself (maybe not as it was an "aside" I think) but it may save me time trying to track it down myself if he is able to jog my memory. That said I will have a go now and give myself a space to try and find it (it is sometimes easier once you actually make an effort) It was not this forum by the way.

I remember who it was but it is a little difficult to track down the post as it was in the nature of an "aside" and search terms are not immediately apparent to me. Actually I have pm'd the poster now and perhaps he will be able to tell me if I have interpreted his post correctly or even remember it (it goes back a good few months if not more like a year) Perhaps I should wait for an answer from him so as not to "put any words in his mouth".

Can I go a little off topic? I have heard (if I recall correctly) that the effects of "gravity" can be derived simply using Special Relativity. If that is so , can Minkowski Space-time diagrams be roped in to illustrate how objects move in the vicinity of mass and energy?

Do you mean me personally or "you" in the sense of "one" ? I am not qualified to define it myself as I am struggling to understand the concept at the outset (I am reading about intrinsic curvature at the moment to perhaps give you an idea of where I am in this regard) If you mean in the sense of "one" ,does that imply the phrase can be used to mean different things ,perhaps depending on the context?

I feel that this is a fairly common expression but what does it actually mean? If I write the phrase "The surface of spacetime" what does it describe? As far as I have been able to understand ,spacetime is a mathematical construct and consequently am I right to think that "the surface of spacetime" is also a mathematical construct and not a physical object as such? Is it a region where things happen? Is the event horizon of a BH such a region? Are there other examples? I think I have been told that you can make a surface mathematically in spacetime by holding one of the variables constant. Would this be right?

Thanks , that seems important to me .

Sorry if I sound hypothetical (and thick) but are you saying that the effects of relativity are not consequent on the speed of light being constant regardless of the inertial frame of reference? Suppose the MM experiment had given the expected results would we have had (a different version of) SR and GR anyway?

Thanks , that is great fun but I am not trying to understand time dilation per se. It is the particular assertion in the video shown on the OP that interests me as I have mulled over this possibility many times in the past and this is the first time I have come across this assertion. It boils down (I think) to that (in the body at any rate according to him) there are processes ongoing that run at the speed of light. Now I know atoms do not move at the speed of light but if there is any physical process in the body (or any other physical environment) that depends on the speed of light for it to function I would "bank" that information and ,as they say it would be "food for (my) thought" So ,is it yes or no? Is the speed of light absolutely inbuilt into all physical processes ? If we could create an em radiation free region of the universe would that region just "cease to exist" ? Is such a "region" totally impossible

Is the explanation in the video correct when it says that the bodily processes proceed at the speed of light ? This is a quote from the video. (around 5 min 36 seconds) "....so for any bodily activity to occur on earth the photons in your body have to travel a certain very tiny distance....." Is that rigorously true? If so I think I would find it very helpful. I think it would actually be even more helpful if that "finding" can be generalised to all matter (not just living matter).

Religious beliefs and practices may not be easily defined. It is not my thread. I doubt the OP will scold you for being OT even if he thought you were.

I don't see the link between the practice of individual making (rewarded) successful guesses and the formation of doctrines (presumably shared by the group). Isn't that where group behaviour becomes important? Any group behaviour at all is better (in evolutionary terms) than behaviour based on the individual (if that is even possible at that stage of human existence)

If (as seems indisputable) social cohesion gave an evolutionary advantage then ,if religious beliefs and practices can be linked to improved social cohesion (and there were not alternative ,competing methods of fueling social cohesion then the case for religious practices providing an evolutionary advantage would be very strong. Can that link be made? Is Phi's speculation about imagination a separate issue ?(kind of like the distinction between superstition and organized religion)

It is a good question. Why did social groups with "religious" beliefs prevail over groups where these beliefs were less formed? I feel it may be connected to warfare and conflict.. It is always the case in conflict that a leader is required to focus energy in times of emergencies. Religion allows potential leaders to showcase their qualities . If they pass the test of devotion to these imaginary folk then their other qualities may also become apparent. It is also a respectable reason to dispense with their services and pass the baton to a new leader (ritual murders of chieftains have been discovered in Europe). Religion and warfare seem intertwined. In our (mine at any rate) distaste for religious beliefs we should not overlook the system of resolving issues by armed conflict we are still wedded to and which is surely a far more pressing "problem".

To say that logic is an extract of the physical world may be true but it is also true to say that it is part of the physical world. Is the relationship a hierarchical one? Logic ,as a phenomenon only arises when the world is structured in such a way as to allow it to (attempt to) "look back at itself" but is it wrong (almost hybris) to posit that logic is foundation of the universe per se? (allowing us to imagine an entirely anarchic universe in theory) In passing, those happen to be the opening words of the Bible ("In the beginning was the word (=Logos in Greek) )... I didn't follow your heavy objects/light objects example , but doesn't logic always (by "definition" ) get the right answer eventually? Doesn't it just mirror the "outside" world albeit in a convoluted ,roundabout manner?