Memammal Posted October 28, 2016 Posted October 28, 2016 (edited) But lets improve the scenario 2: rain is falling along the ruler while the observer slides from one time stamp to another. IOW, the present is the crossing event between the position of the observer and some rain drop. In this scenario, the future is not "already there", and the past is not "frozen". If you understand what I mean. I think I might have covered this by means of my follow-up: In scenario 2 [snip]... Rather think of it as a moving observation or flowing experience. The observer is experiencing a next moment (the technical term is qualia). Hence, it is our observation/experience that moves on- or through a static timeline (or through our embedded-in-spacetime lifeline). Next time you walk around the house, think of it as a moving observation from one spacetime coordinate (moment) to the next. The fact is that we are not able to observe a spacetime coordinate that sits somewhere in the "past", I mean in "our past". The only things that we can directly observe from any time stamp are very specific and depends on distance. ------------- (edit) I mean, the objects that we can observe all belong to the past, but they do not represent "all the past". They are the objects that lie at a specific distance and at specific time stamp of the past. All other events that are a time stamp that does not correspond to this particular distance are not (directly) observable. Yes, we can not observe everything...not even in "real time"...but there is no need to; it does not mean it never "happened" or never "existed". koti wrote: Just so we are on the same page, I do not have a problem with the "capacity" of nature as to the amount of information in it. Rather I have a problem with the concept of introducing this amount of information representing future events "instantly" at the BB. This instant inctroduction of information is in my opinion inevitable in the block universe concept where past, present and future events are co-existing in some kind of continuum. Take space and the BB as an example...big bang is an ongoing process whereas the future events of time in the block concept would have to be introduced instantly unless the properties of time are not universal which is highly improbable IMO. Define "instantly" and no, it did not have to happen at the BB. As you correctly pointed out, the BB is ongoing. It has also been "ongoing" on the other side of what we refer to as the BB singularity (on the minus side of that ruler). I do understand that it sounds unbelievable, but consider this. Everything that is contained in the universe as we know it at present have been part and parcel of the singularity...that singularity has just been expanding and unfolding over what we perceive as "time" (i.e. the so-called 13.8 billion years)...but it was all contained within the tiniest imaginable fraction of space. I have to disagree...you're implying that time has fundamentaly different properties and is essencialy a different entity depending on what models we use to define it. Read Tim88's post in another thread with his overview of time. It boils down to different ways of perceiving, describing and using time (and as a side note, I don't think he mentioned Planck time). I know that in physics time is measured with a clock, but consider this quote: Time is a component quantity of various measurements used to sequence events, to compare the duration of events or the intervals between them, and to quantify rates of change of quantities in material reality or in the conscious experience (Wiki: Time). Further to this, you may want to consider this section of the same article: Physical time. There are, however, also various philosophical concepts of time and this brings us closer to this discussion: Philosophies Of Time. In this discussion you may want to think about conventional time (moving time/now) as something along the lines of presentism and the notion of a static time dimension as being associated with eternalism (many now's). I think the rest of it resolved itself, so to say? But that way opens the floodgates for all sorts of paradoxes and fallacies about time travel. Perhaps not so simple after all? I think he meant that the observer is naturally progressing along his lifeline, experiencing different events/moments at consecutive coordinates...not "artificially" relocating himself to other coordinates in either the past or future. Due to the fact that events are carved in stone and thus pre-existing (in said model), there can be no time travel paradoxes. Edited October 28, 2016 by Memammal
koti Posted October 28, 2016 Posted October 28, 2016 (edited) I think I might have covered this by means of my follow-up: Yes, we can not observe everything...not even in "real time"...but there is no need to; it does not mean it never "happened" or never "existed". koti wrote: Define "instantly" and no, it did not have to happen at the BB. "Instantly" as per my understanding in this context has to be defined by causality - something happened and then as a result something else happened and that result has to be after the cause. From this I draw a conclusion that in the original block concept where the future is a done deal, "the future" had to be introduced at the BB and that "event" had to happen instantly. Or...maybe what I just wrote is totaly false because we know jack sh** about time. As you correctly pointed out, the BB is ongoing. It has also been "ongoing" on the other side of what we refer to as the BB singularity (on the minus side of that ruler). Are you saying that there was something ongoing before T0? I do understand that it sounds unbelievable, but consider this. Everything that is contained in the universe as we know it at present have been part and parcel of the singularity...that singularity has just been expanding and unfolding over what we perceive as "time" (i.e. the so-called 13.8 billion years)...but it was all contained within the tiniest imaginable fraction of space. Actualy the BB singularity and implications of it do not sound ubelivable to me. This stuff is (hopefuly) for quantum gravity to determine and I don't have a problem with this even now before we get any answers. What I have a problem is with time...it is possible in my opinion that the BB singularity very well might not be "unfolding over what we perceive as time" as you stated above. I have a feeling that we are prisoners to these kinds of notions when in fact we haven't made a leap yet to grasp time in its true form. Take Newtonian space as an example and how the view of it changed with the introduction of SR and GR - I think we are still to make a similar leap concerning the concept of time. Read Tim88's post in another thread with his overview of time. It boils down to different ways of perceiving, describing and using time (and as a side note, I don't think he mentioned Planck time). I know that in physics time is measured with a clock, but consider this quote: Time is a component quantity of various measurements used to sequence events, to compare the duration of events or the intervals between them, and to quantify rates of change of quantities in material reality or in the conscious experience (Wiki: Time). I know that I am balancing on a thin rope by not giving scientific reasoning for what I'm about to say but...The wiki definition of time you quoted above just consolidates my view that we know exactly jack sh** about time. The above definition is just hopeless clinging onto GR trying to explain the nature of time. I'm afraid it says nothing more than - "go learn GR" Further to this, you may want to consider this section of the same article: Physical time. There are, however, also various philosophical concepts of time and this brings us closer to this discussion: Philosophies Of Time. In this discussion you may want to think about conventional time (moving time/now) as something along the lines of presentism and the notion of a static time dimension as being associated with eternalism (many now's). Too much to read in too little time. Will save these for later, thanks Memammal. I think the rest of it resolved itself, so to say? Not really Edited October 28, 2016 by koti
studiot Posted October 28, 2016 Posted October 28, 2016 memammal I think he meant that the observer is naturally progressing along his lifeline, experiencing different events/moments at consecutive coordinates...not "artificially" relocating himself to other coordinates in either the past or future. Due to the fact that events are carved in stone and thus pre-existing (in said model), there can be no time travel paradoxes. 'Progress along' implies a contradiction with the block universe. Some of (the best) earlier writers in relativity discussed our perception of time at great length and also considered this relevant as it conditions our attempts to describe and model the physical phenomenon we call time. Think about a small child, who only understands right now! and a goldfish who forgets where the beginning of his bowl is by the 'time' he has circumnavigated it.
Memammal Posted October 28, 2016 Posted October 28, 2016 @ koti: Yes man, you are getting there ...even correcting or questioning me for using a conventional (aka intuitive) terminology when describing the "unfolding (of the universe) over what we perceive as time". Are you saying that there was something ongoing before T0? Well, I am not saying that. The model implies it. That is why I extended the ruler to both -infinite and +infinite on either side of the BB @ zero. The hypothetical events/moments prior to the BB are (still) equally real. Actualy the BB singularity and implications of it do not sound ubelivable to me. This stuff is (hopefuly) for quantum gravity to determine and I don't have a problem with this even now before we get any answers.What I have a problem is with time...it is possible in my opinion that the BB singularity very well might not be "unfolding over what we perceive as time" as you stated above. I have a feeling that we are prisoners to these kinds of notions when in fact we haven't made a leap yet to grasp time in its true form. Take Newtonian space as an example and how the view of it changed with the introduction of SR and GR - I think we are still to make a similar leap concerning the concept of time. Nicely put. Fact of the matter is that we (or most of us) have already become accustomed to the idea of the BB, so it is not a stretch of the imagination. Still, if you think about it and in the way that the first generation must have thought about it...it is an astonishing feat. EVERYTHING in our (observable) universe was in that singularity. Nothing, zilch, was ever added. So all that "information"...past, present and future...were already pre-packaged. Our conventional way of looking at it is that it took 13.8 billion years (and counting) for it to unfold...but WHAT IF it had all existed already in the form of a block universe...and we just happened to observe it in (or interpret it as) different stages happening over "time"..? So you might as well ask (and many have) how did it all get in there, how "long" did it take for it to be assembled in the first place..? 'Progress along' implies a contradiction with the block universe. Some of (the best) earlier writers in relativity discussed our perception of time at great length and also considered this relevant as it conditions our attempts to describe and model the physical phenomenon we call time. Think about a small child, who only understands right now! and a goldfish who forgets where the beginning of his bowl is by the 'time' he has circumnavigated it. Every now and again I mistakenly use conventional terminology in order to explain something. Fortunately there are the likes of you to correct me. Thanks and well said. One of the best ways to describe it i.m.o. is akin to what I used earlier: a moving observation or a flowing experience.
koti Posted October 28, 2016 Posted October 28, 2016 (edited) Think about a small child, who only understands right now! and a goldfish who forgets where the beginning of his bowl is by the 'time' he has circumnavigated it. How ironic that his bowl doesn't have a beginning Edited October 28, 2016 by koti
studiot Posted October 28, 2016 Posted October 28, 2016 memammal a moving observation or a flowing experience. Here we are talking about the way we perceive time, which is why I offered some new viewpoints. I agree about the use of the word experience and it is certainly conventional to talk of time flowing or the passage of time (time passing) to avoid the word moving as I noted in an earlier post. Does time flow for the goldfish or small child? koti How ironic that his bowl doesn't have a beginning Yes I had noticed, that was why I offered the example. But both please consider this. Another viewpoint is to divide the time axis in a similar manner to the mathematical definitions partitioning infinities real and potential infinities. This was where my introduction of y = x2 was leading.
Tim88 Posted October 28, 2016 Author Posted October 28, 2016 (edited) [..] OK, back to my numerical sequence. Let me use the analogy of said number sequence (from -infinite to +infinite) being placed on a (very long, well basically infinite) ruler (or measuring tape). For the purpose of this discussion think of this ruler/measuring tape to be the time dimension, a flat foundation on which the 3-D events are "constructed". Now consider two scenario's: 1. Point zero (theoretically in the middle of the ruler) corresponds to the present time, the now. All the positive numbers relate to the future, all negative numbers to the past. Consider yourself as the observer in the form of a tiny toy standing on top of the zero. So if you want to move the now, the zero (with the toy on top of it) has to move and as such the entire ruler has to move. Hence the question what is the now, the zero, the ruler moving in relation to? This refers to the moving now, the tensed or presentist theory.[..] As I already had debunked that misconception about presentism in the thread on 3D space and presentism, I now did it there once more, with more elaboration. Except for a few more comments to michel I won't comment further until after considering your references, and based on those adding what may be useful in answer to the points 1-3, as so far nobody else did. Scenario 1. I disagree completely. Making the ruler moving is complete nonsense IMHO. It corresponds to a geocentric view of the Universe, as if the observer was really at the center and dictating how the ruler must do its job. To me, it is wrong. [...] Yes, I agree; and it's even incompatible with presentism, as I elaborated here. It's more compatible with eternalism in a 4D Spacetime, as there "time" is a kind of distance that people progress over - which brings us back to the "double time" issue that you brought up. The good thing is that most of us now seem to roughly agree about what "time" is (as differentiated in duration, sequence and instant); the problem seems to be more a matter of understanding how that fits in with the different models of Space / Spacetime. The fact is that we are not able to observe a spacetime coordinate that sits somewhere in the "past", I mean in "our past". [..] Yes, exactly. What you have been saying was quite clear from the start. Moreover, we can walk to the left or to the right, but we cannot walk back in time - it's simple as that! The "moving arrow of time" on top of "eternal time" remains an issue for the block universe, and due to that issue as well as the mixing up of the two very different concepts "length" and "time", it does in my opinion more to make less sense of physics than to make more sense of physics. PS, this reference by memammal sketches very clearly the point that we deem very unconvincing (bold emphasis mine): Skow is more impressed by an alternative idea called the “moving spotlight” theory, which may allow that the past and future exist on a par with the present. However, the theory holds, only one moment at a time is absolutely present, and that moment keeps changing, as if a spotlight were moving over it. This is also consistent with relativity, Skow thinks — but it still treats the present as being too distinct, as if the present were cut from different cloth than the rest of the universal fabric. [..] The experiences you had a year ago or 10 years ago are still just as real, Skow asserts; they’re just “inaccessible” because you are now in a different part of spacetime. In short, 4D Spacetime as reality can hardly escape a "double time" consisting of two very different time concepts that are equally true physical reality. But in fact, the "eternal" time distance is superfluous for physical reality. Removing that superfluous part we're left with 3D Space (+ the ordinary "time" concept) which doesn't have such issues. Moreover it has more explanatory power and is intuitively easier to understand. I already compared block universe to a cuckoo in a sparrow's nest; but increasingly I view it as people throwing the baby away with the bath water because nobody needs a baby, only to replace it by a Frankenstein's monster. OK, I'm already reading them, most of it goes rather quickly (I'll number them): [..] 1. Minkowski space 2. Relativistic dynamics And until I have more time to try and explain the various kinds of block universe models and the somewhat misleading interpretation of "frozen events" (as if it prohibits movement...opposed to change), let me leave you with a link to an article about a recent attempt by some of the world's most renowned physicists to reconstruct the block universe model (which seems to be very fitting to the thread): 3. A Debate Over the Physics of Time According to our best theories of physics, the universe is a fixed block where time only appears to pass. Yet a number of physicists hope to replace this “block universe” with a physical theory of time. Let me also add these: 4. Time, Free Will and the Block Universe (copied from other threads) 5. Growing Block Universe[..] 1. Once more, it's the math that the two models of reality share; apart of a single sound bite by Minkowski, there isn't anything particular about his block universe! Let me remind you of the fact that Langevin elaborated on that math formalism in order to promote the 3D Space model of reality. But maybe someone can explain how a literal interpretation of "curved" spacetime could be helpful. 2. I didn't know about that field; but IMHO it tries to deal with unproven interpretations of QM. For people who think that Feynman diagrams should be taken literally as action back in time (but apparently that's a fable), eternal "time" could be convenient. In contrast, for people who think that Bell's theorem implies "instant action at a distance", the Lorentz ether is most convenient, as Bell also said. In my eyes we should stay with our feet on the ground and focus on the explanations of the established facts of physics. 3. https://www.quantamagazine.org/20160719-time-and-cosmology/ At least that's about "block" vs. "presentism", citing the different opinions. apparently Smolin is also "fed up" with block, like I am now. And "blockers" are trying to explain the arrow of time. However, this is just trying to explain a problem that the model causes! Trying to fix a problem of the model isn't helping to make sense of the physics - just as repairing a broken saw doesn't cut wood. And the "growing spacetime model: "Space-time itself is growing as time passes". Sorry, but to me that's just hilarious! - causal set theory for predicting cosmological constant: that is suggested to be based on "block". However, at first sight, it's in fact based on GR math. 4. After shooting down the straw man, there's a discussion on block universe: - "It emerges that the feeling we have of the passing of time is nothing more than an illusion of human perception due to the asymmetry of the time axis: we can remember the past, but we cannot remember the future." That's again an attempt to solve a problem of the model, instead of showing how the model can help solving problems! - the link to "arrow of time" was broken - and forwarded me to a sex page! - "The conclusions presented here relating to the block universe model follow directly from Einstein’s theory of general relativity": that's just more bunkum. - "It is true that there is a time dimension defined within the universe. And for an observer within the universe, objects appear to change with respect to this time axis. However, this apparent flow of time is just an illusion of human perception due to the asymmetry of the time dimension." Is there anyone here who found that a helpful explanation of how "eternal time" can be experienced as a measure of change? - there is supposedly no beginning of the universe because "The entire spacetime block is laid out as one unchanging structure." But then, to be consistent, neither did anyone of us have a beginning; we were never born, but instead "laid out as one unchanging structure" as well. Problem solved?? The author regretfully shows the same lack of rigor in promoting eternalism as in criticizing presentism... - energy: nothing to do with "block" - Wheeler-DeWitt Equation : there's an issue that I don't know of, that "the rate of change of the state of the universe with respect to time is zero". No doubt that is open for different interpretations, but "block" explains it as follows: "The notion of evolution is not applicable to the universe as a whole since there is no external observer with respect to the universe, and there is no external clock that does not belong to the universe". Great. But totally unconvincing, as no "outside clock" is needed for establishing the existence of a rate. I now think more and more of empty perimedes-like philosophical debates... and that's quite the contrary of what I intend with this discussion. 5. Growing block in wikipedia. Interesting additional problem brought up there: we cannot know when "now" is with that model! And (of course), apart of the more intuitive aspect as it's closer to Absolute Space, there is no suggestion of how the concept can be useful for better understanding physics... Just one left: http://www.journals.uchicago.edu/doi/10.1086/392846 Regretfully my institution has no subscription to that journal. Memammal, please summarize useful aspects of "block" for physics according to that article, thanks! Edited October 28, 2016 by Tim88
Memammal Posted October 29, 2016 Posted October 29, 2016 (edited) Tim, I started reading the first part of your post only to realise that we seemingly find ourselves on very different pages i.t.o. understanding the block universe model. I think you may have a misconception thereof (it seems evident from that first part of your post that I read), but maybe it is just me and the writers of all the articles that I already provided that just don't get it. I thought we were "past that point" of the discussion, but I think the main difference of opinion lies in the way we understand presentism vs eternalism..? Anyway, I will attempt to attend to your post at a later stage when I have enough time and try to dissect it in the hope that we are just misunderstanding each other. In the mean time, maybe this (admittedly very basic) picture helps to illustrate tensed (presentism) vs tenseless (eternalism) and the block universe: But both please consider this. Another viewpoint is to divide the time axis in a similar manner to the mathematical definitions partitioning infinities real and potential infinities. This was where my introduction of y = x2 was leading. studiot, I think we find ourselves slightly more on par w.r.t. understanding the block universe model. I was expecting a next move from you, read it between your lines, so to say. When you mentioned the fishing bowl, I thought you were heading towards a spherical/circular-like hologram, i.e. where the four dimensions start curving back onto themselves, where infinity meets infinity and where events/moments end up going around in circles (i.e. we bend that ruler and the whole caboodle with it until the two ends touch each other again). That seems to be one of the candidate paradigms out there in theoretical science land and something that is not entirely implausible as it seems somewhat "natural". It may open a whole new can of worm(holes), but then it may resolve quite a few others (like the uncertainty of quantum behaviour). Don't take me seriously on this though; I am just throwing it out there... What I am seeing/understanding from your description is something similar, but without the two ends meeting up again. Your description/equation seems to enforce an exponential space enlargement. I assume something resembling a (square?) cone like figure which would enlarge from the singularity across its y axis, i.e. vertically like this illustration of Minkowski space (although this illustration depicts the narrow point as being the present, almost like my presentism illustration where the now sits at the zero on the ruler): Is this more or less right? I don't see a problem with an enlarging square-cone-like representation instead of the square block. The underlying principle remains more or less in tact, no? Perhaps you should rather elaborate a bit on your idea..? PS. Or are you perhaps implying the growing block universe? Edited October 29, 2016 by Memammal
studiot Posted October 29, 2016 Posted October 29, 2016 memammal, I rushed for time (ha ha) right now, but I see you are online so here is a quick response to your post#208. You really need to understand real (actual) and potnetial infinities (it's quite easy) for the rest of it. https://www.google.co.uk/?gws_rd=ssl#q=real+and+potential+infinities The use of y=x2 is a simple dummy function, it could be anything within reason. The point is not about the function, it is about the drawing of it. Let us say I have drawn the part between x=1 and x = 100. That does not say that it does or does not exist for x<1 or x>100, just that I haven't drawn it yet. Does this help?
Memammal Posted October 29, 2016 Posted October 29, 2016 (edited) Back to Tim: I managed to work my way through your post, but I sense a reluctance in you to accommodate anything that does not fit Tim's reality. I find it somewhat ironic and a bit frustrating considering the fact that you attended that lecture that explained how our brains process (real) reality for the purpose of storing it in our internal memory. I find it equally frustrating that you seemingly want to drag old paradigms out of the dark ages and present them to us (because they best fit Tim's reality), while the post-Einstein schools of thought have gone in a different direction. In any event, I want to copy a comment that I made to koti: We are indeed speculating and debating models without having definite answers, but we should at least be able to separate the wheat from the chaff. Science as we know is a dynamic process incorporating a multitude of different methodologies. It is definitely not a popularity contest. I think the single biggest challenge is to be able to scientifically differentiate between- and consider the merits of what seem sensible to our somewhat restricted (human and earth-bound) sense of reality, or intuition, and any paradigms that seem to be in conflict with it (in stead of frowning upon the latter). Let me comment on a few issues that you raised: As I already had debunked that misconception about presentism in the thread on 3D space and presentism, I now did it there once more, with more elaboration. I don't think you did. You only merged it with Tim's reality. Are you saying that time moves or that it does not move, that the now moves or that it does not move? Yes, I agree; and it's even incompatible with presentism, as I elaborated here. It's more compatible with eternalism in a 4D Spacetime, as there "time" is a kind of distance that people progress over - which brings us back to the "double time" issue that you brought up. The good thing is that most of us now seem to roughly agree about what "time" is (as differentiated in duration, sequence and instant); the problem seems to be more a matter of understanding how that fits in with the different models of Space / Spacetime. No, it is definitely not "more compatible with eternalism". Yes (emphasis on most of us) * [EDIT: To be revisited] * Yes, exactly. What you have been saying was quite clear from the start. Moreover, we can walk to the left or to the right, but we cannot walk back in time - it's simple as that! The "moving arrow of time" on top of "eternal time" remains an issue for the block universe... This is where I stopped reading the first time around. I am afraid to say that this substantiates just how little you know about the block universe model. Left, right but not back? What MOVING arrow of time? Go back a bit and read the discussion between koti, studiot and myself. In short, 4D Spacetime as [TIM's] reality can hardly escape a "double time" consisting of two very different time concepts that are equally true physical reality. But in fact, the "eternal" time distance is superfluous for physical [TIM's] reality.Removing that [TIM's] superfluous part we're left with 3D Space (+ the ordinary "time" concept) which doesn't have such issues. Moreover it has more explanatory power and is intuitively easier to understand [for TIM]. Corrected above. 3. https://www.quantamagazine.org/20160719-time-and-cosmology/ At least that's about "block" vs. "presentism", citing the different opinions. apparently Smolin is also "fed up" with block, like I am now. And "blockers" are trying to explain the arrow of time. However, this is just trying to explain a problem that the model causes! Trying to fix a problem of the model isn't helping to make sense of the physics - just as repairing a broken saw doesn't cut wood. And the "growing spacetime model: "Space-time itself is growing as time passes". Sorry, but to me that's just hilarious! - causal set theory for predicting cosmological constant: that is suggested to be based on "block". However, at first sight, it's in fact based on GR math. Smolin & Co. are mostly fed-up with the future-is-set part of the block universe. Nonetheless, there were and still are attempts to replace- or improve on the block universe model (as the article alluded to). That is the nature of science. Some are more successful than others (Mordred and ajb previously pointed to some of these). The article highlights the fact that it is easier said than done to just throw out the block universe model as an accurate reflection of (Einsteinian) reality. And why do you keep on implying that the block universe model caused the (problem of the) arrow of time? - "It emerges that the feeling we have of the passing of time is nothing more than an illusion of human perception due to the asymmetry of the time axis: we can remember the past, but we cannot remember the future." That's again an attempt to solve a problem of the model, instead of showing how the model can help solving problems! Any model should attempt to best reflect nature's reality, don't you think? - "The conclusions presented here relating to the block universe model follow directly from Einstein’s theory of general relativity": that's just more bunkum. How does it misrepresent Einstein's theories? - "It is true that there is a time dimension defined within the universe. And for an observer within the universe, objects appear to change with respect to this time axis. However, this apparent flow of time is just an illusion of human perception due to the asymmetry of the time dimension." Is there anyone here who found that a helpful explanation of how "eternal time" can be experienced as a measure of change? I explained it all on the previous page. I wanted to suggest that you need to think outside the block, but maybe that would not be entirely accurate. - there is supposedly no beginning of the universe because "The entire spacetime block is laid out as one unchanging structure." But then, to be consistent, neither did anyone of us have a beginning; we were never born, but instead "laid out as one unchanging structure" as well. Problem solved?? What do you mean we were never born? What problem? Read the previous section in this thread (between koti, studio and myself). - Wheeler-DeWitt Equation : there's an issue that I don't know of, that "the rate of change of the state of the universe with respect to time is zero". No doubt that is open for different interpretations, but "block" explains it as follows: "The notion of evolution is not applicable to the universe as a whole since there is no external observer with respect to the universe, and there is no external clock that does not belong to the universe". Great. But totally unconvincing, as no "outside clock" is needed for establishing the existence of a rate. Refer to the inherent differences between my scenario 1 & 2 and look at that picture that I inserted above. I now think more and more of empty perimedes-like philosophical debates... and that's quite the contrary of what I intend with this discussion. Yes, this sums it up. What did you intend? To get a model that best describes earth-bound human (or Tim's) reality opposed to nature's reality? 5. Growing block in wikipedia. Interesting additional problem brought up there: we cannot know when "now" is with that model!And (of course), apart of the more intuitive aspect as it's closer to Absolute Space, there is no suggestion of how the concept can be useful for better understanding physics... And of course, i.t.o. presentism, that is quite a significant problem not knowing when (opposed to where) the now is. Again, are we not looking for models that best describe nature's reality? Just one left: http://www.journals.uchicago.edu/doi/10.1086/392846 Regretfully my institution has no subscription to that journal. Memammal, please summarize useful aspects of "block" for physics according to that article, thanks! Was that not the paper that I suggested that you or Michel could read as it may shed some light on Michel's insistence that there must be time within time? It is available, just Google it. I don't see why I need to. I don't have a problem with time within time. EDIT: ADD SEPERATION--------------------------------------------------------------------------------------------------------------------------------------------------------- Does this help? Let me look at it again, thanks studiot. Edited October 29, 2016 by Memammal
Tim88 Posted October 29, 2016 Author Posted October 29, 2016 (edited) Yes indeed Memammal, we have seen how the understanding of people who adhere to "eternalism" have ideas about "presentism" that strongly differ from many of those who actually use presentism concepts; and also the other way round. Many arguments are wrong both ways, due to mutual misunderstandings of the concepts. For example, the picture that you posted contains the same fallacy about "presentism", as if past experiences were not real. And of course, I sense a similar reluctance from your side concerning a view of reality that doesn't fit with Memammal's reality, or that differ from a popular school of philosophy (who said that he didn't want a "popularity contest"?). There is no expectation from my side that ideas that have been developed in the course of ten or twenty years would tumble in a philosophical discussion, and neither should you have such an expectation. It's already very surprising - and a nice surprise indeed - that we are much on the same page about what "time" is. Luckily the topic of discussion here is only indirectly concerned with those issues. What matters is how to give helpful descriptions for understanding relativistic physics; the goal is to offer alternative metaphysical explanations to those who are not satisfied with the physics of "shut up and calculate". By now I have picked up enough of the clarifications to proceed with a first attempt to play "block universe" advocate for points 1-3 on behalf of those who want to promote that concept. In post #163 I made a more logical start of the kind of things that a metaphysical background should explain, and I used the 3D Absolute Space explanation. Now, 2 pages of discussion further, it may be possible to make a start with the competing explanation. 4D ABSOLUTE SPACETIME interpretation:1. INERTIA.Acceleration corresponds to a curved trajectory through Spacetime. Acceleration can be easily distinguished, but eternal time is "frozen" so that more is needed for explaining dynamic forces. For that (as well as for explaining our experience of "now") it is proposed that there is a kind of dynamic time as well, corresponding to a "now" that is literally moving along the eternal time distance. That allows for the dynamics.Apart of that, Absolute Spacetime can of course just as easily as Absolute Space explain why rotating discs have absolute effects. I'll try to correctly formulate the block universe explanations:2. SAGNAC. For simplicity of description, let's choose a Spacetime slice in which the disc axle only moves along the time direction. If a laser light is sent along the rim in both directions, the light rays will trace equal paths through Spacetime until they hit the detector, if the detector also only moves along the time direction. However the detector traces a curved path through Spacetime so that the point where the rays meet with the detector is not symmetric. The interference pattern is a function of the detector's trajectory relative to Absolute Spacetime.3. EHRENFEST PARADOX. Lorentz contraction only occurs in the direction of motion.For simplicity we choose again a Spacetime slice in which the disc axle only moves along the time direction. But HERE MY MIND GOES BLANK; I don't know how to explain this with the block universe, as the trajectories through time complicate the description quite a lot. Anyone? Edited October 29, 2016 by Tim88
Memammal Posted October 29, 2016 Posted October 29, 2016 The good thing is that most of us now seem to roughly agree about what "time" is (as differentiated in duration, sequence and instant); the problem seems to be more a matter of understanding how that fits in with the different models of Space / Spacetime. Yes (emphasis on most of us) * [EDIT: To be revisited] * It's already very surprising - and a nice surprise indeed - that we are much on the same page about what "time" is. Tim, I would like to revisit this at some "point in time". I have a suspicion that I might have jumped the gun with my reaction...without paying proper attention to what you stated in brackets (which I have now marked in red). This may, or may not be critical. I suspect it is. Lol...this after I agreed that most of us know what time is... For example, the picture that you posted contains the same fallacy about "presentism", as if past experiences were not real. Just as a side note: the wording on the picture may give a somewhat fallacious impression, but philosophically speaking it is still regarded as a significant differentiating factor between presentism and eternalism. Less so than with the future, but still. I can elaborate on this, but let us leave it for "now". I will revert and react, if needed, to the rest of your last post sometime tomorrow.
michel123456 Posted October 29, 2016 Posted October 29, 2016 Yes, exactly. What you have been saying was quite clear from the start. Moreover, we can walk to the left or to the right, but we cannot walk back in time - it's simple as that! (sorry I have skipped the last long posts of this thread) I don't know if I was clear enough. If double time exists, then time is not a line anymore, but a surface. Furthermore, if the past is not "frozen", it becomes something very similar to the future: something that can change (randomly). In such a way that even if time would "flow backwards" (to be read as a U-turn of the observer), the observer would observe nothing very special happening, only usual "flow" (to be read "usual motion in spacetime"). I know it is wild speculation, but that would make time and space a little more equal. Not to say that in principle, triple time would be needed. Each time for each spatial dimension.
Memammal Posted October 30, 2016 Posted October 30, 2016 (edited) Just as a side note: the wording on the picture may give a somewhat fallacious impression, but philosophically speaking it is still regarded as a significant differentiating factor between presentism and eternalism. Less so than with the future, but still. I can elaborate on this, but let us leave it for "now". If double time exists, then time is not a line anymore, but a surface. Furthermore, if the past is not "frozen", it becomes something very similar to the future: something that can change (randomly). In such a way that even if time would "flow backwards" (to be read as a U-turn of the observer), the observer would observe nothing very special happening, only usual "flow" (to be read "usual motion in spacetime"). I know it is wild speculation, but that would make time and space a little more equal. Not to say that in principle, triple time would be needed. Each time for each spatial dimension. Refer to my post in the other thread "3D Space, relativity and presentism". Michel, I don't follow your reasoning as to why a line will become a surface with "double time". Your comments w.r.t. the past not being frozen seem like (valid) criticism against presentism. And as for your third paragraph, again sorry, but I don't follow. I think we need to have a proper chat about time. This thread seems to be appropriate as we have already raised it various times. Refer to among others: Post #195 Post #201 In the last post (#201), I gave various references that deal with the concept of time. This one needs careful attention: Physical time PS. Or do you prefer to rather discuss TIME in the thread "3D Space, relativity and presentism", Tim, as you already started with it there? Edited October 30, 2016 by Memammal
studiot Posted October 30, 2016 Posted October 30, 2016 Refer to my post in the other thread "3D Space, relativity and presentism". Michel, I don't follow your reasoning as to why a line will become a surface with "double time". Your comments w.r.t. the past not being frozen seem like (valid) criticism against presentism. And as for your third paragraph, again sorry, but I don't follow. I think we need to have a proper chat about time. This thread seems to be appropriate as we have already raised it various times. Refer to among others: Post #195 Post #201 In the last post (#201), I gave various references that deal with the concept of time. This one needs careful attention: Physical time PS. Or do you prefer to rather discuss TIME in the thread "3D Space, relativity and presentism", Tim, as you already started with it there? memammal please don't follow Tim's example and start sprinkling every post with links to other threads with the admonition that '....has already posted it here', which will lead to a long if not endless chain of links. Most of us will not even follow to the first one. So please say what you want to say in the thread in your usual quite succinct style. I look forward to your promised thoughts on my last post in this fashion.
Tim88 Posted October 30, 2016 Author Posted October 30, 2016 (edited) (sorry I have skipped the last long posts of this thread) I don't know if I was clear enough. If double time exists, then time is not a line anymore, but a surface. Furthermore, if the past is not "frozen", it becomes something very similar to the future: something that can change (randomly). In such a way that even if time would "flow backwards" (to be read as a U-turn of the observer), the observer would observe nothing very special happening, only usual "flow" (to be read "usual motion in spacetime"). I know it is wild speculation, but that would make time and space a little more equal. Not to say that in principle, triple time would be needed. Each time for each spatial dimension. I understood it differently, as expressed in my attempt to explain inertia and rotating discs by means of the Spacetime view. The two "times" of that view are clearly of different kinds; and the one like length is frozen. What matters here is if you or others think that it somehow can be helpful for understanding relativisitic physics by means of Minkowski's view of reality. [...] I think we need to have a proper chat about time. This thread seems to be appropriate as we have already raised it various times. Refer to among others:Post #195 Post #201 In the last post (#201), I gave various references that deal with the concept of time. This one needs careful attention: Physical time PS. Or do you prefer to rather discuss TIME in the thread "3D Space, relativity and presentism", Tim, as you already started with it there? "Time" is definitely part of the presentism topic [edit: however I now get the impression that you would like to start a general discussion on the topic "TIME" - that would deserve a thread of its own!]. Here we are not discussing time, but proposing explanations for relativistic physics. The discussion here focuses on the explanations of relativistic physics; it seems that some of you completely forgot about that. I already included the "double time" issue in my explanation by means of the block universe; if you or someone else disagrees with how I phrased the Minkowski explanation of inertia and Sagnac, please improve on it. Note also the still lacking Block universe explanation of the Ehrenfest disc. Edited October 30, 2016 by Tim88
michel123456 Posted October 31, 2016 Posted October 31, 2016 (edited) I understood it differently, as expressed in my attempt to explain inertia and rotating discs by means of the Spacetime view. The two "times" of that view are clearly of different kinds; and the one like length is frozen. Yes and no. Yes because I understand your point about the "The two "times" of that view are clearly of different kinds; and the one like length is frozen." And No because the "frozen" part corresponds to what we call a path. A path is the inscription of motion. It is a way to describe, both in space and in time, the motion of an object. It is not motion itself. IOW I am thinking now that the 4D Block Universe describe paths. It does not describe what is actually happening. It is frozen picture of a dynamic system. It is not a frozen system. Edited October 31, 2016 by michel123456
Tim88 Posted October 31, 2016 Author Posted October 31, 2016 Yes and no. Yes because I understand your point about the "The two "times" of that view are clearly of different kinds; and the one like length is frozen." And No because the "frozen" part corresponds to what we call a path. A path is the inscription of motion. It is a way to describe, both in space and in time, the motion of an object. It is not motion itself. IOW I am thinking now that the 4D Block Universe describe paths. It does not describe what is actually happening. It is frozen picture of a dynamic system. It is not a frozen system. Yes, exactly. It was you who made me realize that in order to make (somewhat) sense, Monkowski's Spacetime reality must add a dynamic time on top of it's 4th dimension (which Einstein rejected) in order to "unfreeze" it. As you have been soaked in explanations by "block timers" for some time on this forum, do you think that I correctly described this in point 1. Inertia? If not, how would you put it? It is my view that only by "test running" such conceptual models, we can judge their eventual usefulness for making sense of the physics. Further, I realize that could be useful to add another explanation attempt, the ether according to Einstein. However nobody seems to be sure how to understand his concept, and maybe it never could work. I now consider to start a thread on that question, and to only add it here if we can discover some useful concept that he might have had in mind.
Memammal Posted October 31, 2016 Posted October 31, 2016 (edited) Here we are talking about the way we perceive time, which is why I offered some new viewpoints. I agree about the use of the word experience and it is certainly conventional to talk of time flowing or the passage of time (time passing) to avoid the word moving as I noted in an earlier post. Does time flow for the goldfish or small child? [sNIP] But both please consider this. Another viewpoint is to divide the time axis in a similar manner to the mathematical definitions partitioning infinities real and potential infinities. You really need to understand real (actual) and potnetial infinities (it's quite easy) for the rest of it. https://www.google.co.uk/?gws_rd=ssl#q=real+and+potential+infinities The use of y=x2 is a simple dummy function, it could be anything within reason. The point is not about the function, it is about the drawing of it. Let us say I have drawn the part between x=1 and x = 100. That does not say that it does or does not exist for x<1 or x>100, just that I haven't drawn it yet. Does this help? studiot, sorry it took me so long to react to this. I actually did not want to derail the discussion by introducing new idea's. I was misled by your equation rather than to pay attention to what you have written...which is exactly what you pointed out to me in your follow-up. As I understand it you are suggesting that we perceive the time axis as a set of infinities (which agrees with my ruler example), with the present and past as real (completed) infinities and the future as potential infinities. Something like a time axis consisting of potential infinities that are being filled up by real infinities (bracketed) when those moments are being experienced, so to say..? @ Michel: Those last two sentences of yours seem to be on the right track. Read it in conjunction with the above... It is frozen picture of a dynamic system. It is not a frozen system. Edited October 31, 2016 by Memammal
koti Posted October 31, 2016 Posted October 31, 2016 Hi guys...this especially means (in alphabetical order): ajb, Memammal, Michel123456, Mordred (no math pretty please), Studiot, Tim88.Or anyone else who can contribute to the overwhelming vastness of this thread by simplifying it. I have a request for you guys... I don't remember who but someone once stated that if you can't summarize your idea in one sentence then your idea is not of interest.Could each of you summarize the essence of what you are trying to convey in a single sentence so it will become easier for me to grasp this thread?
Memammal Posted October 31, 2016 Posted October 31, 2016 (edited) Could each of you summarize the essence of what you are trying to convey in a single sentence so it will become easier for me to grasp this thread? (Our experience of) the universe is like a box of chocolates (with acknowledgement to Forrest Gump). Edited October 31, 2016 by Memammal
Mordred Posted October 31, 2016 Posted October 31, 2016 (edited) No math grr. The principle of relativity and block "presentism" are contradictory. Due to time symmetry, there is no need for a preferred frame such as Lorentz ether. (Sorry needed two sentences) Edited October 31, 2016 by Mordred
Tim88 Posted November 1, 2016 Author Posted November 1, 2016 (edited) [..] I have a request for you guys... I don't remember who but someone once stated that if you can't summarize your idea in one sentence then your idea is not of interest. Could each of you summarize the essence of what you are trying to convey in a single sentence so it will become easier for me to grasp this thread? Sure: It will be useful to discuss [...] the explanatory features of each model, as each answers questions such as "what is really happening" slightly differently [- take your pick! ]. That citation from my first post was in one sentence what I try to convey -------------------------------------------------------------------------------------------------------------------------------------------------------- OK then, I'll give here now an extended overview including a more detailed car example, of how one conceptual model helps to make sense of relativistic physics. You can just choose the topic of interest. Physical effects such as inertia and time dilation can be modeled as caused by an underlying Lorentzian 3D background (non-material Lorentz "ether" / "vacuum" / "Absolute Space"), but a more widespread view is that they are caused by a Minkowskian 4D background in which "space" and "time" form a single substantial entity (Minkowski block universe). Both models are proposed as CAUSING the space-time metric. One might ask, what is the practical difference? I'll here elaborate how a modern variant of an Absolute Space in "action" can help to understand classical as well as relativistic effects as caused by motion through Space; this is basically the view of reality as Lorentz used when teaching GR. Additions by others are welcome, and I invite those who adhere to some kind of Absolute Spacetime concept, to post the corresponding alternative explanation(s) for making sense of our observations. ABSOLUTE SPACE model of reality Classical physics originated from a Newtonian Absolute Space in which inertial frames are postulated to be in uniform translational motion relative to Space. It also has an independently "flowing" Absolute Time. In my opinion it's obviously a misconception to view time as "flowing", as "flow" implies ds/dt which contains itself "time"; the "flow of time" confusion may stem from the perceived "flow" of physical processes. Consequently there can also be no "arrow of time", as time does not traverse distances. Time is just as unsubstantial as for example temperature. How this works with GR will be illustrated next. The Lorentz transformations relate to Newtonian "inertial frames" and originated from a Lorentz ether concept which is similar to Newton's Absolute Space. Time is not anymore independent from Space, as it is affected by motion through Space. Einstein attempted to get rid of SR's inertial frames by means of General relativity, as he hoped to obtain a theory in which also acceleration is truly relative. However GR did not attain that goal, despite Einstein's early claims that it did: we can generally distinguish acceleration from gravitation so that imaginary "inertial frames" can be set up just as in Newton's mechanics. We may therefore still suppose that a 3D "background" exists that affects and determines our measurements. Absolute Space is directly associated with distances and lengths. But different from Newton's mechanics, measurements of distances and lengths are affected by means of Absolute Space. In contrast with distances, time is a measure for the progress of physical processes; however our measurements of time are similarly affected by means of Absolute Space. And just as in the old theory, the absolute state of motion (speed) cannot be detected but a change of motion with respect to Space can be detected. 1. Newton argued for this with his BUCKET EXPERIMENT: in this model of reality, the inertial force is explained as the result of the water's co-acceleration with the bucket relative to Space. Compare also De Sitter: even in an otherwise empty universe, rotation of an object is likely to result in inertial effects. GR has now sufficiently been verified to strongly doubt truly Machian alternatives such as proposed by Brans-Dicke. Inertia can even be understood in a straightforward manner as self induction for the simple case of the electron (QM improves on this quantitatively); this fact suggests the possibility that one day a unified theory may be found that explains all inertia as due to change of field energies. Other improvements to Newton's Space following from Maxwell and Lorentz are that radiation does not propagate like particles but as waves (or, since QM, like wavelets), so that the speed of light is determined by the Space that it propagates through. Matter is affected by motion just the same as Heaviside's moving EM fields. In addition, effects of ROTATING DISCS are similarly easy to intuitively understand by means of Absolute Space: 2. SAGNAC EFFECT. For simplicity, let's first pretend that the axle is at rest in Space. If now laser light is sent along the rim in both directions, the light will, just like any real wave, propagate at a fixed speed through Space. During that time the detector will move away from the one ray and towards the other ray, so that the interference pattern is a function of rotation speed relative to Absolute Space. 3. EHRENFEST PARADOX. Lorentz contraction only occurs in the direction of motion. If the disc would be at rest in Space, then a measuring chord will be slightly contracted as it is laid along the rim, but not as it is laid along the diameter. Consequently the circumference will appear to be more than 2pi times the diameter (and there isn't any paradox to start with). The combined effects of Lorentz contraction, time dilation and relativity of simultaneity (as elaborated next), assure that the same phenomena occur with rotating discs in any inertial reference system. 4. FAST CAR We are now going to make use of inertial reference systems related to a fast car that is driving over the ground, and we consider how we can understand the observed phenomena to be due to motion through Space. The non-inertial motion of the ground will be neglected in the following examples. Similar to classical mechanics, we are free to choose the landscape as pretended "rest frame" (neglecting rotation), in which case the car is "moving" (even if we are inside). But different from common practice, we assume here that the car conductor has set up an inertial reference system according to the assumption that the car is in rest and the ground is moving under it. For clarity, in the following illustration the car drives at an impossible crazy speed for a contraction factor of 2. However we'll assume a more reasonable speed of 300m/s (1080km/h) for the calculated effects. That allows the use of simpler equations: the Lorentz contraction factor is now 1-0.5v2/c2 = 1 - 0.5E-12. I'll follow here the analysis methods of Einstein-1905 and Bell, sticking to a single convenient inertial reference frame. Let's say that there are clocks c1 and c2 above two openings in the floor of the car, and these clocks have been "Einstein synchronized". The car driver now drops two balls, presumably simultaneously, so that from the car's perspective : ________________________ | | | |_ | ___ c1 c2 ___| / \-- ----2m---- ---/ \ _______\___/__o__________o___\___/_________ <- v According to the car the balls were dropped simultaneously at 2m distance, so that they also hit the moving ground at 2 m distance. According to the ground however the car is length contracted, and the balls are not dropped at the same time so that they hit the ground at different times. From the ground's perspective: ____________ | | | | | | v ----> / \- -----o-/ \ ____________\_/_o_______\_/_____________________________________ ____________ | | | | | | v -----> / \- ----- -/ \ ________________o__________\_/_______o_\_/____________________________ Now, according to the Absolute Space (Stationary ether) world view, this is what really happens, physically: When you are driving your car, in general both your car and the landscape are in motion, resulting in what may be figuratively called different perspectives of the same reality. This is an essential point to keep in mind before reading on. For simplicity of explanation we'll first pretend in this introduction that the landscape is, by pure chance, in "absolute rest". a. The car is then Lorentz contracted as caused by the car's motion through space. This would be expected if fundamentally all matter consists of some kind of waves. In this example one could (in principle) measure that the car is Lorentz contracted. b. The car's synchronization is messed up due to the car's linear acceleration, as can be easily understood by working out the timing errors from the light pulses as they propagate through Space (we may ignore the air). Thus the car's synchronization is chosen such that it seems as if the one-way speed of light (also called "closing speed") is the same in both directions. According to the ground (here by chance the true "view"), it is obvious that the car's synchronization is wrong. c. As per the relativity principle these effects combine in such a way, that the car conductor can measure (in principle) that the ground is slightly length contracted, by 1 picometer. According to a ground observer, the second ball fell a distance of 2 picometer too far due to the car's synchronization error; accounting for the car's length contraction, the distance between the balls is thus 2meter + 1 picometer. The car driver, assuming that he is in rest in Space, measures that a ground length of 2 meter + 1 picometer fits in his distance of 2m rest length. Accordingly he concludes that it's the ground that is length contracted. Of course, the car driver may still choose to regard himself in motion, in which case he'll measure that the ground is not length contracted but instead his car is length contracted. And just as in Newtonian mechanics, the same relationship occurs between two reference systems that are both in absolute uniform translational motion. In other words, in the general case both inertial reference systems provide in general a somewhat "distorted" perspective on reality, with the distortion here explained instead of hand waved away as a "perspective" effect due to "relativity". Note that these combined effects are not a "conspiracy", as the Lorentz transformations follow from the conservation laws. d. Moreover, in this special case the clocks of the car truly tick slower; this is physically understandable by means of the "light clock" illustration. Due to the car's (mis)synchronization of clocks (in principle together with its length contraction, but that's negligible at this speed), it seems from the car's perspective as if instead the ground clocks run slow. This happens as follows. It takes 6.67ms on a ground clock for the car distance from C1 to C2 to pass over it. During that time, the car's clocks advance by the same time minus 3.3fs, becase the car's clock run in reality slower. But as C2 has been set 6.7fs ahead of C1, the car driver will measure a time interval of +6.7-3.3 = 3.3fs more "car time"; consequently, to him it looks just the other way round. In other words, the car driver measures that the ground clock is "slow". In general no reference system corresponds to Newton's "Absolute Time"; all show Lorentz's "local time". And we noticed that relativity of simultaneity cannot explain length contraction and time dilation, however it does explain the reciprocity of these effects between inertial systems. We now turn it into a "TWIN PARADOX" scenario. Just as with the earlier examples, a paradox won't even appear. The specially conceived racing car will take a turn and drive back without changing speed, such that both clocks keep the same speed (note that it may be difficult for a car to keep both clocks at exactly the same speed when going straight, and even more so when taking a turn!). e. On the way back, the car is just as much length contracted as before and ideally the clocks are correctly tuned for the new inertial "rest" system, as can be easily understood by considering that in this special case the clocks underwent an identical speed-as-function-of-time influence by motion through Space. f. The car now passes a clock on the ground that it passed on the outbound leg after the synchronization. After 2x30km, the driver will notice that his clocks have "lost" 0.1 ns on the ground clock. That is as expected, since his clocks (in this simplified case) truly ticked slower all the time. As the Lorentz transformations form a group similar to the Galilean transformations, the exact same phenomena will be observed between a car in motion relative to a ground that itself is also in motion. While this point may be less intuitive due to our limited mental capability to conceive such complexity of different relative motions and effects, it is not too difficult to verify this fact mathematically. The relativity principle is the same as in Newtonian relativity, but the transformation equations are different. A consequence of the different standards and clock settings, is that the velocities according to one system are not (or only approximately) equal to the sum of that system's velocity and the measured velocities with that system. That's commonly know as high speed "velocity addition", but it is correctly understood as a system transformation of velocities (the rules of mathematics are not violated in a "space warp"!). As a matter of fact, that was already demonstrated in the car example: according to the car driver, a light ray propagates at c relative tot he car. But the same light ray does not propagate at v+c according to a ground observer. We can thus understand why the transformation of velocities of objects between systems in relative motion is not a simple sum as in classical mechanics. Important philosophical consequences of the "Absolute Space" view of reality are that time and distance have not been totally robbed from their classical, intuitive aspects; however, physical length in the direction of motion as well as time rate are affected by motion through Space. In other words, only Space is causal in that view. Moreover, the classical, Newtonian concept of "time" had to be abandoned, and only a relativistic kind of "presentism" can be maintained. Absolute simultaneity is not accessible to human observation, we must settle for pragmatic "relative simultaneity". It should perhaps be noted that while the effects of SR have been well established, this is not entirely the case with GR; theoretical research on alternative theories is continuing. Nevertheless the gravitational fields of all mass (incl. the "relativistic mass" from radiation and EM fields) certainly have absolute effects on the speed of light as well as on clock rates. In a recent post I clarified how Einstein first derived gravitational time dilation These effects have been verified as follows. 5. GRAVITY PROBE A (Vessot-1980) : an atomic clock is sent up to high altitude after which it comes down in almost free fall. a. At the start, the clock ticks at the same speed as clocks on Earth. b. At its highest point, the clock is nearly in rest but less affected by the Earth's gravitational field: a higher potential energy corresponds to a higher clock frequency that of clocks on the ground - gravitational time dilation was measured. c. When falling down, just before impact the clock is again at the same hight but at high speed. Here the remaining effect was purely SR time dilation, and so the ground station measured a reduced clock rate after subtracting the assumed "classical" Doppler effect. It maybe worth noting that for the theoretical case that the ground is in "absolute rest", the SR effect relates to "absolute" kinetic energy, in contrast to the GR effect which relates to gravitational potential energy. 6. GRAVITATIONAL LENSING a. Light bending: When light passes nearby a star such as the Sun, the gravitational field bends the light towards the star somewhat like an optical lens, due to a gradient in propagation speed; the tricky point here is that according to GR, the effect is anisotropic. As a matter of fact, Einstein used the Huygens construction for predicting the effect (the corresponding Wikipedia article fails to inform the readers on this point and suggest the exact contrary). b. Shapiro delay: radiation that passes near to a heavy mass such as the Sun will not only bend but also delay. This is immediately understood as due to the slower propagation speed in the gravitational field (inconsistently, the corresponding Wikipedia article mentions the slowdown of light that is denied in the other one). 7. SINGULARITIES - Black holes: "true" or fully developed black holes are a modern extension of GR, outside of the intended use - and Einstein found the idea unphysical. The Absolute Space model of reality would have difficulty with the inclusion of an "inside" of black "holes"; however, according to a number of physicists who in recent years performed combined QM-GR calculations and simulations, "true" black holes cannot form - just as one would intuitively guess from the Absolute Space model. I hope that the advantage of such an intuitive model for understanding is obvious from the given examples. Even if one disagrees with some aspect of it, it's transparent what one disagrees with, and why. I'll leave it for others to elaborate on alternative explanations of such cases according to Minkowski's (or their own) view of reality. Edited November 1, 2016 by Tim88
Memammal Posted November 1, 2016 Posted November 1, 2016 studiot, sorry it took me so long to react to this. I actually did not want to derail the discussion by introducing new idea's. I was misled by your equation rather than to pay attention to what you have written...which is exactly what you pointed out to me in your follow-up. As I understand it you are suggesting that we perceive the time axis as a set of infinities (which agrees with my ruler example), with the present and past as real (completed) infinities and the future as potential infinities. Something like a time axis consisting of potential infinities that are being filled up by real infinities (bracketed) when those moments are being experienced, so to say..? Just thinking out loud...one could also use real infinities to describe "macro events" in order to differentiate it from quantum behaviour's potential infinities..? @ Michel: Those last two sentences of yours seem to be on the right track. Read it in conjunction with the above... Just so that we are clear, I was referring to their context as you used it in your original post... IOW I am thinking now that the 4D Block Universe describe paths. [cut]. It is frozen picture of a dynamic system. It is not a frozen system. I am not convinced "paths" is the appropriate term while frozen pictures in a dynamic system might have been better, but otherwise this is getting quite close. @ koti: that would be a worthwhile contender for your one/two liner question...to be read in context with our most recent discussion spread across the previous two pages. My reference to the box of chocolates was only a skin deep analogy, purely philosophical and the first thing that jumped into my mind. It referred to our lifelines being embedded in the block universe, each chocolate (moment) pre-packaged but the flavour remains unknown until you unwrap- and experience it. I already included the "double time" issue in my explanation by means of the block universe; if you or someone else disagrees with how I phrased the Minkowski explanation of inertia and Sagnac, please improve on it. I find any notion of "double time" within the block universe model as somewhat dubious. The principle of relativity and block "presentism" are contradictory. I tend to agree.
bvr Posted November 1, 2016 Posted November 1, 2016 (edited) Thank you Tim88 for this excellent presentation.I think it would be helpful to add a little clarification to this paragraphe: We may therefore still suppose that a 3D "background" exists that affects and determines our measurements. Absolute Space is directly associated with distances and lengths. But different from Newton's mechanics, measurements of distances and lengths are affected by means of Absolute Space. In contrast with distances, time is a measure for the progress of physical processes; however our measurements of time are similarly affected by means of Absolute Space. IMO length and time measurement are not affected by Absolute Space as such, but by the effect of electro-magnetic propagation.When an EM wave is formed in a moving system, the propagation of the wave is independent of the motion of the system.That means that the centers of all the EM waves stay in one single frame wherein the waves propagate as growing spheres.But since the shape of all the objects depends on EM forces which thus propagate independently, the moving objects (including rulers and clocks) are affected in such a way that in there own frame, the propagation of the EM waves will always appear to be isotropic and their measured speed will always be the same (=c), despite of any change in velocity of the object's frame. Edited November 1, 2016 by bvr
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