Tim88

Is https://en.wikipedia.org/wiki/The_Selfish_Gene not clear?

Correcting two glitches, sorry for noticing them too late: - Michael -> Michel -"fictitious speeding up of far away clocks" -> "fictitious speeding up of far away inertial clocks"

I had bad luck with keyword search, so that in 5 minutes I did not find Gal.1:18-20. And I do not understand the word "mistrust" in the context of scientific discussion. Many years ago I followed -and participated in- about one year of such discussions on a dedicated forum. When I noticed this thread I was curious to see how far the discussion here has come, and if the discussion relates to a good overview of arguments. If so, I could perhaps read something that I did not already know, and add some essential information that is lacking. But as I clarified in post #657, I do not consider it worthwhile to participate in a discussion in which only a fraction of the evidence is considered. I also gave links that point to information that I found useful (indeed, I merely threw in a few links in order to point to that information in the most useful way), although possibly such have already been fully discussed here. It certainly is not my purpose to discuss here discussions on websites or to repeat the contents of several books; I consider that a waste of time. And indeed I already formed an opinion, as obviously you did as well; however that could be altered if I there is a somewhat scientific, non-apologist theory about a historical Jesus that can explain (mostly postdict) an impressive number of details of the New testament books, the early church writings, etc. The theory that has the most convincing arguments and that shows the least amount of serious problems is the most likely to me. As the OP did not answer my questions, I do not intend to spend more time on this thread. My best wishes with the further discussion.

Red bold face mine. What you say here above strengthens my stated objection, but perhaps it was not sufficiently clear what I objected to for the sake of michael and robin. I commented on the claim that "during periods of non-inertial relative motion, the twin A clock ticks faster than B's own clock within the B spacetime system", saying that it is not a valid physical description as it leads to messing with the laws of physics, even causality. Apparently "the B spacetime system" referred to a reference system for physical measurements of the accelerating twin in which the twin is constantly in rest. If I misunderstood that, then my comment may have been misdirected; but from your above clarification I think that I correctly understood you. In SR the laws of physics hold "in" (with respect to) inertial frames. The laws of physics do not hold with respect to non-inertial frames, as you apparently acknowledge here above, as according to the laws of physics according to SR clocks do not tick wildly, and there can be no superluminal speeds. In SR the kind of "accelerated frame" that you discuss is not suitable for physical inferences, as you nevertheless appear to do; the term is even misleading as it relates to an ensemble of an infinite number of Lorentz transformed inertial reference systems. Such a virtual "accelerated frame" does not even correspond to measurement results obtained with a real, extended physical system. But any of those inertial reference systems is suited for physical descriptions, without things like breaking the speed of light or the fictitious speeding up of far away clocks. According to SR, the twin who turns around observes a Doppler effect due to his turnaround; no laws of physics are messed up, nor does any law of physics need to be messed up to understand the observation of the correct number of ticks of the stay-at-home's clock by the traveler. Compare Langevin's description on p.51 of https://en.wikisource.org/wiki/Translation:The_Evolution_of_Space_and_Time It's similar in classical mechanics. For example, on a fair there is a merry-go-round on which people may freely move. It can then happen that a guy looses contact and flies outward until crashing against the outer rim. Geometrically he observed coordinate acceleration relative to the merry-go-round, until hitting the outer rim (as a matter of fact it happened to me once, with one rib broken). Suppose that this is discussed in a thread in which one desires to get better physical insight in how this should be interpreted according to classical mechanics. In that thread someone states that whatever is measured is real, and in the merry-go-round space-time system, a force acts on the guy that accelerates him towards the rim. Would you not object, and clarify that in classical mechanics such a magical force is merely fictitious, due to pretending that the rotating platform is not rotating, but in rest? Or would you claim that textbooks are wrong as fictitious force should be called real force? Even that forces which originate from nothing that could be their cause, are not a hindrance for physical insight? PS. One more illustration that I thought of, as in this discussion there was a comparison with using maps (e.g. #234 by Mordred). Imagine the captain of an airplane using a series of country maps (Mercator) when flying around the world. His copilot remarks that coastlines change shape when they are flying over them. Really? Is that a good physical description to explain what is happening?

I'm glad that you agree that it should be mentioned as it is of general importance, and that nevertheless, by chance your calculation as stated is not (very) wrong. But, sorry, it seems to me that you do not fully understand it: "Assume the proper acceleration of the primed system is virtually instant. Then, the loss of synchronization of primed-frame clocks during their proper acceleration is negligible, and those clocks remain in sync (similarly as in all inertial scenarios)", is faulty. [edit:] And I had overlooked that you started the pulse at the same time as the acceleration. That is too messy... What will make it correct without effort, is to simply add, like Einstein did*, that first S' is accelerated and after acceleration the clocks are being synchronized according to the standard operating procedure. And put then all coordinates and times to 0 as per the picture, with a light flash at t=0. The synchronization issue between clocks of S and S' was not my point, as I had not noticed that glitch. What I tried to convey, is the synchronization between moving clocks C1' and C2' along X'. For acceleration to a medium speed of <0.1c, C1' and C2' remain approximately synchronized to S, because their trajectories are almost identical - considering displacement, your added equation in your last post applies to both C1' and C2'. Consequently they are not synchronized to S'. At higher final speed also length contraction plays a role, but it works the wrong way(!) for synchronizing those clocks to S'. You can easily figure out for yourself that the moving rear clock will slightly delay on the moving front clock according to S. For correct synchronization to S', the moving rear clock must instead advance on the moving front clock. That is a task for the observers of S'. *compare: §3 of http://www.fourmilab.ch/etexts/einstein/specrel/www/ PS comment on the following post by Celeritas: Yes, that's a smart solution!

1. Yes 2. Yes 3. No: the direction does not matter. If they otherwise do exactly the same, the result (comparison of their age with the stay-at-home) must be exactly the same too.

With the Earth's "frame" (standard inertial reference system) one can easily measure the height of the lower layer of the atmosphere as well as the speed of the muon, which is deduced from the measurements of path length and two coincidence times. That's 4 measurements in practice. ... I don't really recognize the formula for gamma in your summary, but it does have to do with a kind of scaling. Only, due to relativity of simultaneity, it's not a simple kind of scaling except in some special examples. In particular, due to relativity of simultaneity the effects are mutual: each system considers the other system to be length contracted and time dilated.

Because the object is moving according to the Earth's rest frame, so that according to SR it is length contracted by factor γ according to our measurements. From that knowledge we can deduce that according to the object's rest frame, the object is in rest and thus not length contracted but a factor γ longer than what we measure (or infer, as it's practically impossible to measure). It is therefore just the opposite of what you ask for: it is simply "The length of the moving object as observed in the Earth's rest frame multiplied by γ gives you the length of the moving object in the moving frame". Edit, addition: By the relativity principle it is just the same for a moving object in the object's rest frame: as you surely remember in the muon example, an observer in the muon's rest frame will measure the lower atmosphere as 2 km high, and may deduce that the height of the atmosphere in the Earth's rest frame must be 2x5=10 km. And just to make sure that terminology did not contribute to confusion: "the moving frame" = "the moving object's rest frame"

Very nice Celeritas Indeed, your introduction is simpler than the Wikipedia one that I referred to with the same purpose. After a quick glance I noticed a glitch: you forgot to mention that after acceleration the clocks in S' should be synchronized to S' before doing measurements. That makes your presentation not erroneous, I think, but perhaps this is by mere chance: Your example concerns measurements between two pairs of spatially separated clocks. After acceleration the clocks of S' are not all synchronized to S'. In particular, the clocks along X' must be "Einstein synchronized" to S' in order to "directly measure", as you call it, similar relationships along X and X'. And of course, all the times that are measured are directly affected by the synchronisation convention of S. As clocks along the Y' axis remain simultaneous with each other under acceleration in X direction, the fact that S' is not a fully valid SR reference system has no effect on your example. PS. One can get rid of clock synchronisation issues and obtain more "direct" measurements by means of using only one clock and mirror per system for two-way measurements, from the clock to the mirror and back to the same clock.

Let's see... I ask where Paul supposedly did that statement that you introduced, and you answer "by mythicists [..]" ... next your comment on arguments by Doherty starts with the question if I made that summary - which I coincidently found with DuckDuckGo... No more questions! Right. I think that it's reasonable to assume that either Christianity started with a real, earthly Jesus, or that it did not start with a real, earthly Jesus. Those hypotheses lead to very different expectations concerning the early church, New testament writings, etc. In this long thread, was any attempt made to compare the evidence (pro and contra) of both hypotheses? If so, starting with which post? [edit] To clarify: for example post #656 is a fraction of 1/4 of the comparison that should be made, in order to allow forming a well informed opinion. One way to go about would be to compare books such as by Doherty with books such as by XXX (I have Doherty's book and I know many now out of date Christian books, but I don't know which is a good up-to-date book that promotes and defenses the earthly Jesus hypothesis).

The "proper" or "rest height" of the dense part of the atmosphere is ca. 10 km. As I (and others) already explained, 2 and 3 are wrong (and no need to care about irrelevant distractions concerning "point particles"). BTW you could have noticed from the foregoing discussions that I do my own thinking. PS I will now search back the post where I started to explain the error that has nevertheless been repeated over and over since, and add it here. OK according to me it was my post #131, just before I added the muon link - but possibly someone else clarified it before me: "Objects are predicted to contract if they change velocity on the way from A to B. [i meant: if their speed increases] Obviously their contraction, as measured on Earth, cannot contract for example the distance between London and Paris! We even would have different contractions at the same time of that distance if objects with different speeds were flying in-between. New emphasis added. I don't know why that (and many follow-ups) did not "click"...

[edit:] Probably that phrase by Paul is disputed, where is it? Further, the Josephus section is disputed, in part because it does not exactly mention "James, the brother of Jesus". See the last part of the page http://www.christianorigins.com/doherty-muller.html

Yes, exactly: controversial implies disputed, not generally accepted.

As others already stated, it's wrong: according to the Earth, the Earth's atmosphere is in rest and NOT contracted; the muon is in motion, and therefore contracted. And what of my discussion about relativity of simultaneity? However, all such discussions assume a good understanding of the basic assumptions of SR. Perhaps VandD is right that it's better to read up some more about the basics on Internet. For example you could read about the Michelson-Morley experiment, as it illustrates the practical meaning of both the first postulate (about inertial frames) and the second postulate (about light propagation) as well as length contraction. It was one of the experiments that led to SR. The Wikipedia article is rather good but perhaps overly complex: https://en.wikipedia.org/wiki/Michelson%E2%80%93Morley_experiment

A few people in this thread pretended that science does address his questions. Perhaps it warrants a discussion in the philosophy forum, where, I suppose, every scientific question goes that experiments cannot answer.

Agreed, controversy does suggest something bigger. Possibly a few in the following list resulted in some controversy: http://math.ucr.edu/home/baez/physics/Relativity/SR/experiments.html#Experiments_not_consistent_with_SR

Wow this thread already nears infinite length... for me too much to go through, but as you are the OP, likely you know it someone already referred to this overview: https://en.wikipedia.org/wiki/Christ_myth_theory Notably Doherty's book The Jesus puzzle is worth studying, as it has a scientific approach to the issue. Based on some indications he got the idea that perhaps Jesus never really existed, and next he tested that hypothesis by looking for evidence that could falsify or render more support for it. But likely that has already been discussed in this thread. Edit: here's a link: https://en.wikipedia.org/wiki/Earl_Doherty#The_Jesus_Puzzle

As far as I could trace it back, the first person who found that relation was Poincare, but Einstein may have found it around the same time: https://web.archive.org/web/20141006134323/http://henripoincarepapers.univ-lorraine.fr/chp/text/lorentz4.xml It was based on the Lorentz transformations, which in turn were based, among other things, on the invariance of observations of the speed of light. As you can see there as well as in Einstein's corresponding paper, §5 of http://www.fourmilab.ch/etexts/einstein/specrel/www/ , the geometric presentation was introduced later. Note also that "addition" can be a bit misleading: the laws of mathematics are of course not broken by SR. As you also can see, the velocity composition equation was derived by means of a Lorentz transformation from one reference system to another one that is in relative motion to the first. The Lorentz transformations predict non-linear effects from speed so that linear additions of the measurements of two such systems should not be expected to work. PS. The term "composition of velocities" is not in the German original which used the German word for "addition"; apparently it was an improvement by the translator!

Yes of course there were. A recent one (what is it already 5 years ago?!) you can find here and I find it a bit amusing (but surely it was very frustrating for the people involved!): http://www.telegraph.co.uk/news/science/8782895/CERN-scientists-break-the-speed-of-light.html

That makes perfect sense to me. However, a thorough analysis of the meaning and consequences of those equations is certainly helpful to deduce what is going on and it serves to weed out interpretations that are incompatible with SR.

Einstein's SR was first agnostic as he tried to get rid of the ether, next he expressed support for the Lorentz ether, and later, in a letter to family of a lost friend, he expressed belief in the block universe as it corresponds to eternalism. Scientists are forced to reject what logical reasoning obliges them to reject, but there always remains freedom of models. Concerning your comments on your diagram, note that in the real world clocks don't always express proper time but are tuned to the reference system for which they service - this is in particular the case with GPS clocks. [edit: removed comment of little relevance]

First of all there is a matter of definitions. "ticking slower" commonly means that the number of ticks of that clock in a certain time period -as measured with a "stationary" reference system with clocks- is less than that of another clock: "ticking slower" = "<number of ticks> / time of one clock is less than that of another clock". And that is just what you are saying, is it not?

Right. However, "velocity" is not a directly observable property. The fundamental, standard measuring method for measuring velocity is to determine the change of position per time interval: v = dx/dt. It is straightforward to analyse that measurement from the Earth's perspective: one can simply determine the times that are recorded when a muon passes two distant clocks, and together with the known distance one obtains the speed. Alternatively one can send the detection signals at near light speed to a single clock, and make corrections for the assumed transit times. By chance, here's a paper about it (just see the "background"): http://www.iontrap.wabash.edu/adlab/papers/S2010_castilow_vest_muon_speed.pdf Obviously, a measurement with two clocks strongly depends on the synchronization of those two clocks; and that is typically done with so-called Einstein synchronization, using light signals. The issue is one of the first things discussed in Einstein's famous paper, and it was already discussed in the literature before SR. - §1 of http://www.fourmilab.ch/etexts/einstein/specrel/www/ Note also the remarks near the end of §2. With that, both methods (two clocks or one clock) depend on the same assumption of the one-way transit speed of light relative to the system S0 on Earth (this is also called "closing speed" due to some disagreements about meaning of words). It is natural for observers on Earth to assume that the speed of light on Earth is isotropic, and this assumption is the standard convention for setting up a reference system. The speed measurement is therefore not as objective as one may intuitively think. For what follows I will pretend that the speed is measured with two clocks, as that is easier to formulate clearly. How is this muon speed measurement by Earth interpreted from a standard reference system S1 that is co-moving with the muon? Here is where "relativity of simultaneity" comes in. According to S1, the earth is moving at great speed upwards so that the speed of light is not isotropic relative to the Earth - instead, it is assumed to be isotropic relative to S1. Consequently, the clocks and time-of-transit calculations by Earth are faulty from the perspective of S1 - and the obtained one-way light speed reading is faulty too. I don't know if this is totally new for you, or if you recall the effect. Now back to what I tried to make clear in post #151. According to S1: S0 (the Earth) measures its heights 5 times larger, and its clocks run 5x slower; when using the simultaneity of S1, people on Earth will therefore measure a too high muon speed. And that is what you would obtain from thoughtlessly doing v=distance/time for time measurements between two clocks. But people on Earth use a simultaneity convention that on its own leads to a too low speed. This is because the bottom clock is advanced on the top clock, so as to measure a light ray passing from the top clock to the bottom clock as passing at speed c (and similarly for a light ray going upward). For the speed measurement, the synchronisation convention compensates for the effects from time dilation and length contraction. S1 can perfectly explain how due to the three effects together - time dilation, length contraction and man-made clock synchronization - people on Earth find exactly the same relative speed between the muon and Earth as S1 finds. In addition, S1 explains from these effects why S0 measures objects in S1 to be length contracted, and clocks in S1 to run slow - all wrong from the perspective of S1, but perfectly straightforward and not due to some mysterious perception effect that defies understanding. Does that help? [edit: slight corrections in phrasing]

OK With that improved phrasing (and you possibly can still edit your earlier post), michel's posts #162 and your #163 are rather amusing together as each put the exact same phrase in bold for exactly opposite reasons. It may be useful to elaborate in michel's thread. [retake:] I don't follow your "also", except if you try to redo what I already did in an earlier post on which you did not comment (#151). It may help to define frames by name, e.g. S0 and S1, and to clarify which perspective you use for each comment. Moreover, scaling (in the sense of what you seem to mean with "stretch") does not work as in simple problems due to difference in assumed simultaneity (clock synchronisation). Mutual time dilation and length contraction cannot be understood without understanding the effect of relativity of simultaneity; but I suspect that you don't fully understand that main issue. Please clarify as it's necessary in order to understand my post #151 as well as most of this kind of discussions. What kind of explanation are you looking for? If it is about how to calculate, that's what SR can tell you. If it is about what "really" happens, then it's just outside the official scope of SR (and very close to the split-off thread). Nobody can prove what hidden reality is, but we know of two interpretations that match the Lorentz transformations, as already mentioned (here or in the other thread). What can be done is to clarify those explanations. Already Celeritas (somewhat) clarified one model; the other one was (somewhat) clarified by Langevin. Notably they do not agree on all points, so that in some instances one has to specify which model one uses. You basically have the choice between block universe and presentism. That's wrong, if I correctly understand you. One has to shut off one's senses (close one's eyes and feeling) in order to not know who is accelerating. Thus the two parts of your sentence are not equivalent: that observer is able to determine that the traveller is not inertial from observing the turnaround. [edit: additional comments]

A "rubbish" comment looks like trash to me - I'm still new here, should I press the Report button?