Tim88

I disagree to turn this thread into a double of the thread that this came from; I already won't reply here to an earlier post of you in this thread that even doesn't belong in there, but in the thread that started all this (the one I called here the "grandmother thread"). That makes two posts that you can recycle by reposting them in the appropriate threads (but in the last post is link missing it seems). In the discussion in which the two models or views of reality are put side by side, each model is given a chance to explain how it makes SR and GR work by means of a couple of simple examples (in the pipeline!). Here it has become clear that how each of those relates to "presentism" or "eternalism", is best clarified by such examples and not by philosophical talk. I'm confident that within a couple of days we will be ready to continue improving on those examples - but we may need help from someone who strongly believes in "block universe". And note that cosmology is not my piece of cake. PS funny that you also tried to disprove relativity; in my case it resulted in a very nice paper (supporting SR) as spin-off.

I would be happier if you don't disagree with the OP's standard usage of terms; it's simply unhelpful - https://en.wikipedia.org/wiki/Turbulence.

Laminar flow can also consist of closed line rotating eddies (often confusingly also called vortexes!), which are obviously not "parallel plates" (and no plates are hypothesized anyway). Probably you confused a practical application of laminar flow with the general theory of laminar flow. But your understanding is roughly correct, turbulence is characterized by chaotic processes caused by instabilities that break up the flow lines, and the local flow changes as function of time.

I'm now working towards a reasonable "fix" so as to keep the example simple without brushing things under the carpet. I'll post more later; first a better summary of points to consider, and next a pragmatic solution (I think, for it's "in progress").

Sure that's not bad - it's indeed called "gravitational lensing". However a big caveat is that the effect is anisotropic. Moreover I get the impression that they don't understand how to consistency apply it; for the phrase "thus lengthening its frequency" sounds rather blurred. Assuming a static, stationary case, frequency cannot and should not change.

Certainly so. I clarified how, if Lorentzian presentism is correct, we can extremely easily explain not only SR but also the intuitive paradox that was raised in the discussion. If someone else would claim that block universe is incompatible with relativity or experience because it implies eternalism, that would be something for a different discussion. I see that you answered when I added the precision "[edit:] or did you simply mean that what we see now is what happened in the past? I already elaborated on that...". So it is unclear if I simply misunderstood you, or not. Apart of that, I believe that it is biology at work - and that's mostly physics. The mathematical 4D aspects of relativity should not be difficult to understand; I think that Einstein explained it in a very understandable way. Those 5000 people were not physics students I hope!

I clarified why it can be explained as stemming from a natural confusion in our minds; and that solves the paradox. And there is only a "flow" of natural processes (including in our heads) which we can interpret as "flow of time". I just explained how that works, and how, in all likelihood, that illusion is created. [edit:] or did you simply mean that what we see now is what happened in the past? I already elaborated on that... Not exactly: there still is a little distance! See my post #22

Memammal, not exactly, and partly quite the inverse - maybe I was just as ambiguous as studiot a few posts back? I'll try again. I fully agree that we should not allow our perception of reality to obscure reality itself. On the one hand our brains intuitively know that "place" and "time" are different, based on experience. That points to some kind of presentism. But on the other hand our brains intuitively associate "time" with "place" and "distance" - and that suggests some kind of eternalism. [edit: Indeed, those conflicting intuitions can create a philosophical struggle in our brains.] Yesterday I came to understand that the way we store memories is apt to mixing up "time" with "location" and "distance". Confounding "time" with ""place" and "distance" comes natural to us, as those memory labels are stored in the same location. Eternalist philosophy can thus be explained as a natural confusion that is caused by the data storage handling of our brains. Based on the earlier mentioned facts I now formed the hypothesis that we actually make use of place and grid cells for storing time and duration memories. I intend to suggest this as a separate line of research to Prof. Moser, who so far has been focused on spatial associations.

This similarly answers the question of studiot: We intuitively know that space and time are different concepts and the aforementioned brain research established that our coordinate system is 3D, just like GPS. At first sight, that may not seem to offer an explanation for eternalism. However, we use dx/dt sensor cells for our spatial navigation, and we try to keep separate and sequentially order spatial memories that are stored on the map of the world that we built up in our head.

Today I went to a talk by Noble prize winner May-Britt Moser. Surprisingly her talk was not only excellent and fascinating, but the information I received relates to the topic here, as our concept of "present" as a separate concept of location is put in doubt. For it connects to Michel's associations of events with space, as well as to my elaboration on how our consciousness processes events. I will try to correctly reflect her team's findings. While such similarities somewhat explain why we associate time with spatial distance, I had the impression that the association is so strong that there should be more to it. For why are people not similarly associating for example force with acceleration, so that they consider the two concepts as a single whole called forceacceleration? And why do we conceptually so strongly link "time" with "space" that we speak of such things as "those dates are close to each other", and "we can place those events in the year 90"? One is easily led to think that our subconsciousness is trying to tell us that time is truly a kind of 4th spatial dimension. But there is another, much more reasonable explanation. Earlier today I contemplated on our memory and the fact that we store experiences as events in our brain, although not very reliably, due to the way we process and store them: A few hours later Prof. Moser explained that in and near to the part of our brain in which we store our memories there are "place" and "grid" cells, which form a variety of spatial maps of our surroundings, completed with "head direction" cells and even "speed cells" (with linear response!) as well as "border" cells, that serve as spatial navigation system for location and distance. This grid cell based navigation system is innate, but enforced and calibrated by means of experiences (events). Preliminary data suggest that the horizontal grid is the strongest developed, and it extends into the hippocampus where memories are stored. Obviously (my own thinking) this is used by animals as guidance for such necessities as finding back places with food, which also benefits from time information - if only to know which memory of a place is the last, and thus the most actual map. According to Professor Moser, spatial mnemonics work well because they actually use spatial memory; but the same area also serves for memorizing day to day events such as if you had breakfast today. Apparently the (x,y,z) space grid in our head serves to memorize (x,y,z,t) events or snapshots, linked to associated memories. This provides us, in addition to the above mentioned explanations, with a straightforward biological explanation for the strong associations that we make between space / distance and time. Our brain connects memories to a spatial navigation zone, so that the "when and where" is stored in a spatial mapping system. [edit]: slight improvement of phrasing - and here's her Nobel lecture which I now quickly scanned through for checking.

I don't treat objects as points; instead I treat very small parts of an object as points. Hmm that's an interesting angle. Fitting for this topic under philosophy is studiot's remark that objects are not points in space. For example our consciousness has a strong "time" concept whereby signals from our ears and eyes are combined into an idea of "now"; those signals deal with delay times and intuitively we assume that the delay times are all the same. That sense is already unprepared to combine a lightning strike with the following thunder; we must force our perception to understand that those two pieces of information happened simultaneously. Thus our distant "now" experience is a rather simplistic and rudimentary automatic reconstruction, which of course serves very well for our daily lives and our survival. And our consciousness itself is working on a volume of brain, so that our "now" or "present" feeling has a non-zero time interval. For me personally that "present" feeling is a split second. However, I think that it's a well known fact that in memory recall often the sequence of fast following events is confused.

There was at least a confusion due to your use of non-standard terminology, as discovered here above. But now it's a bit a riddle what you do argue... Anyway, continuing, maybe what follows may clear the fog (but leaving out everything related to the "Galilean" confusion that has just been cleared up): (x,y,z,t) is just as important in Newtonian physics as in Lorentzian physics for establishing events. Only the frame transformations are simpler in Newtonian physics. OK, so you use a definition of "presentism" that is incompatible with Lorentzian relativity. Case solved (in principle). Aha, that clarifies (perhaps) more of the misunderstanding; I hope to have better explained it here above. Both Newton and Lorentz based their physics on a 3D physical space. Only Newton ignored some effects that later were discovered to be necessary to include, leading to a more "flexible" role for time (as well as other things, but that's not the point here). OK, your stance is clear enough; this was due to a mutual misunderstanding of terms! 3D Space is just a (meta)physical spatial background for matter, fields and radiation, as discussed and explained in the "grandmother" thread, where the consensus still is that measurement space cannot be mere emptiness, so that we basically have two options which you both reject. 3D (meta)physical Space is of course just as 3D measurement space included in any description of space-time, which is a 4D mathematical model. I'm pretty sure that I already explained that with a link to Einstein's description; probably you just overlooked it. PS I here put it as (meta)physical as it's a matter of interpretation, appreciation and context if you call it "metaphysical" or "physical"; here we're somewhat at the overlap of physics and metaphysics.

Studiot, your contributions are usually interesting but sometimes a bit ambiguous. For example, here you suggest to give support to Memammal's argument, but your elaboration seems to beat it down. Can you clarify? OK, continuing commenting on Mordred, omitting misdirected comments on "absolute time" which is a concept that by definition is not contained in "3D Space": OK that solves one non-existing issue: you introduced here "Galilean relativity" as meaning t=t' which differs from standard "Galilean relativity" (meaning the PoR)! Probably you meant Newtonian relativity. As you surely know: - starting from Absolute Space (3D) and the PoR we will find either Newtonian relativity or Lorentzian relativity. - Newtonian relativity uses the Galilean transformations. Time is "absolute". - Lorentzian relativity uses the Lorentz transformations. Time is "local" or "relative".

The devil is always in the details - and so we now have (top view, bend to the left), still ignoring dynamic effects: 1. The asymmetry of the car, which we chose to neglect and which can be compensated for by adding rear wheel steering: ---------- ¦ ↑ ¦ vr ← \ C1 \ ¦ ¦ ¦ ↑ ¦ ¦ C2 ¦ ---------- I sketched the car almost normal length, else it becomes difficult to picture. Without compensation of front wheel steering, C1 has a greater speed than C2 during the turnaround. 2. The additional inhomogeneous contraction of the car due to the composition of velocities (here sketched with full compensation of effect 1): ← ← ---------- ¦ ↑ ¦ vr ← \ C1 \ ¦ ↑ ¦ / C2 / vr → --------- → → If I see it correctly, there will also be a skew which I did not sketch, but which doesn't matter for the trajectories for this symmetrical case. This effect reduces the distance between C1 and C2. As a result, C1 temporarily has a lower speed than C2 when going into the turn, and going out C1 temporarily has a greater speed than C2. There is leeway for the driver to adapt the central speed of the car so as to keep for example the speed of C1 constant, or the speed of C2 constant, or to keep the speed of some other point of the car constant. The original question has thus been refined to the question if in principle a combination of 1. and 2. is possible such that the result for time dilation is the same as when we just neglect them altogether - that would be neat (and it was the intention of this scenario that we may neglect such effects).

I studied many years ago a related issue, the so-called double Fizeau toothed wheel. The axle twists due to the rotation speed added to the linear speed, in principle exactly by the right amount for the PoR to be maintained. Still, the intention of the full example should not be overlooked, which is to keep it simple, neglecting minor effects, just as in the usual twin paradox a lot of approximations are made. How minor this one is still has to be analyzed, but it can perhaps in principle be compensated by some other imperfections such as the already mentioned asymmetry of the car due to the steering wheels. To be pondered over.

Mordred, that's great, you finally came to the point: your issue is with step 2. The distance between the clocks doesn't stay exactly constant under rotation due to the rotation speed. Right? Why didn't you say so immediately? Indeed, that adds some more complexity to the analysis, which I had not included. [edit: moved some later added text to the next post]

In the OP I ask to comment on my analysis, which I split out in 4 steps for targeted criticism. In the thereupon following posts I explain how my analysis follows the linked analyses of Einstein and Bell. No rapidity or further transformations are required in any of these cases. Come on guys, this is very easy - especially with the already worked out examples: - the effect of circular motion on clock rate was already explained by Einstein; that clarifies step 2. - the method of comparing the identical motion of two objects that follow each other was already explained by Bell; that clarifies step 3. - even the end result for one "moving" clock is given by Einstein, so that instead of following me, you can simply calculate backwards from the easily deduced results for two clocks that follow each other. [edit:] Mordred I see that you added your unnecessarily complex calculation - it's like using a supercomputer simulation for adding groceries. As warned at the outset, it may be much more difficult to find the error in such complexity, regretfully. And the required answer is even missing - I even don't see any mention of the two car clocks! Where do you show that the car clocks C1 and C2 need resynchronization due to the turnaround in order to make the one way speed of light again c for the car, and by how much? Following my analysis, next the correct clock retardation values are found for each clock. As a reminder, we are discussing here the measurement of the one way speed of light inside the car according to the car's clocks C1 and C2 and the ruler on the floor of the car. According to my analysis, for this particular case no synchronization correction is needed after turnaround in order to make the 1-way speed of light again c according to the car. I suddenly notice what seems a disagreement with the referenced paper, according to which a clock at constant speed in a circle keeps the same rate as when going straight: Note that my analysis is immune to that, as C1 and C2 undergo the identical effect from moving along the same circle segment. Could it be that there is an ambiguity in the scenario, so that Mordred is trying to work out an unnecessary complex scenario while I chose on purpose one of the simplest possible scenarios? Anyone, is there a possible misunderstanding here??

While I appreciate your good intentions, this means that you overlooked what I already stated in post #145 and even emphasized in post #151.

And where in his analysis of circular motion did Einstein use rapidity? I didn't see you make an analysis that allows an exact prediction of the time difference according to the ground frame, starting from the initial time difference D. [edit:] Maybe you accept Einstein's result to which I linked in post #3, and which is easy to apply to the two clocks. Starting from that accepted result, calculating backwards (straight line constant speed) you should find the same as me. And as you did not make clear with which step you have problems, let's take it step by step: please clarify the perceived error in my step 1.

Well it doesn't for me; either you're wrong about "presentism", or it doesn't necessarily apply to the 3D Absolute Space concept - just as you have your own variant of the 4D Absolute Spacetime concept. Either way it doesn't matter, since relativity originated from the 3D Absolute Space concept as you probably know. The compatibility of 3D Space with relativity was baked in from the very beginning, while the other concept has been added like a cuckoo egg in a bird's nest. 3D space can only be incompatible with SR if SR is self-contradictory (which I don't think). That means that I do need to say the obvious... If you postulate that Minkowski block universe is correct, then Lorentz ether must of course be incorrect. However, that fact does not prove that Lorentz ether is incorrect; it's called a circular argument. Yes, relativity of simultaneity is important - and the 3D Space interpretation is very different from the 4D Spacetime interpretation. BTW how do you draw such nice pictures? More later

My experience and insight supports the conclusion that the pen is really 3D. Look at my question again: the reasoning here seems to be that since there exists a reasoning that a 4D interpretation matches observations, therefore a 3D interpretation cannot match observations. Do I need to clarify the defect in reasoning?

With new emphasis in bold red: I stay on topic. If useful, the result will be fed back here for interpretations. Note that we already decided to elaborate here on the initial synchronization. [edit:] I'll provide next the elaboration for the first interpretation.

Hi Rasher, I did not claim anything contradictory in Strange's words, but I noticed a difference in interpretation of what you are asking. And I meant "know" in the way you meant it. Thus: can you please clarify, did you mean with "is there a property of velocity that belongs to an object" a. Can we understand velocity as a property of an object (NOT restricting ourselves to direct measurements but also possible inferences)? or b. Is velocity an invariant property of an object ("property" restricted to meaning "directly measurable")? or c. Neither a) or b) but..... For the difference, the gold bar illustration stands (second half).

In the points under discussion: - I made no assumption about "rapidity"; that concept is not used. - I made no use of wordlines or spacetime diagrams. And neither did Einstein and Bell in the referred places. Note also that the later following "twin" clock measurements are not affected by eventual 1-way speed measurements of the car driver. What here instantly became clear to me, is effectively a combination of Einstein's and Bell's above-mentioned instant understandings; my reference to those is therefore not only useful as example but was directly applied. Strangely enough you did not mention any of it in your criticism of my points 1-4...

The context is what I referred to in the post that you reacted on: Newton's definition of motion (incl. "property"), which sounds quite similar to that of Rasher (which is why I looked it up), and to which you replied "Absolutely not". Clearly at least one of us misunderstood the OP! I'll verify next. BTW I have zero "what is relativity threads" as we probably all know that (or at least swansont does), but one thread on two opposing interpretations of relativity. Rasher, in view of the above, can you please clarify, did you mean with "how does the particle "know" that it is moving: a. How does the PARTICLE "know" that it is moving (NOT restricting ourselves to direct HUMAN observations). or b. What do HUMANS OBSERVE about how a particle "knows" that it is moving (and please limit the meaning of the word "properties" to those things that are both accessible to and invariant in direct HUMAN observations). or c. Neither a) or b) but..... To clarify the difference with atoms as illustration: How does a gold bar "know" that it cannot be divided endlessly into ever smaller portions of gold? Is "consisting of atoms" a property of a gold bar? a. A gold bar "knows" that it is made of atoms; and yes of course that's a property of gold. or b. Gold bars did not "know" that they are made of atoms until the 20th century; and until that time atoms were NOT a property of gold.