A puzzle for the SRians
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From: PD on 27 Jul 2010 21:22 On Jul 27, 5:26 pm, kenseto <kens...(a)erinet.com> wrote: > On Jul 27, 3:21 pm, PD <thedraperfam...(a)gmail.com> wrote: > > > > > > > On Jul 27, 1:45 pm, kenseto <kens...(a)erinet.com> wrote: > > > > On Jul 27, 10:09 am, PD <thedraperfam...(a)gmail.com> wrote: > > > > > On Jul 27, 8:50 am, kenseto <kens...(a)erinet.com> wrote: > > > > > > On Jul 26, 5:57 pm, PD <thedraperfam...(a)gmail.com> wrote: > > > > > > > On Jul 26, 4:12 pm, kenseto <kens...(a)erinet.com> wrote: > > > > > > > > Einstein's train gedanken is modified as follows: > > > > > > > When M and M' are coincide with each other......two lightning strikes > > > > > > > hits the ends of the train and the light fronts arrive at M' non- > > > > > > > simultaneously. > > > > > > > Question for the SRians: does this mean that according to the SR > > > > > > > concept of relativity of simultaneity M will see the light fronts > > > > > > > arrive at him simultaneously? > > > > > > > Not necessarily. It depends on the speed of the train. > > > > > > > But for a given pair of lightning strikes, there will be at least ONE > > > > > > reference frame with an observer M" for whom the light fronts arrive > > > > > > simultaneously. > > > > > > But there are infinite nmuber pairs of light fronts that arrive at M > > > > > and M' non-simultaneously. > > > > > Not for a given pair of lightning strikes there aren't. > > > > I didn't specifiy any given pair of strikes. > > > You did say there was ONE pair of strikes on the train and the light > > from those strikes arrived at M' non-simultaneously. You asked if this > > necessarily meant that the light from the strikes would arrive at M > > simultaneously. I said, not necessarily. > > Right any two strikes arrive at M' non-simultaneously will also arrive > at M non-simultaneously. This means that there are infinite number > pairs of strikes that will arrive at M and M' non-simultaneously. > There are two specific strikes that will arrive at M' > simultaneously....these two strikes were genrated simultaneously at > the ends of the train to begin with. These same two strikes will also > arrive at M simultaneously. Why? Because the speed of light is > independent of the motion of the ends of the train. > > >It depends on which pair of > > strikes. Out of ALL the pairs of strikes possible, there is ONE pair > > for which the signals would arrive at M' non-simultaneously and at M > > simultaneously. > > No...all pairs of strikes that arrive at M' non-simultaneously will > also arrive at M non-simultaneously. There is one pair of strikes that > will arrive at M' simultaneously and that pair of strikes will also > arrive at M simultaneously. > > > > > > >But for the others, they would arrive at M' non- > > simultaneously (separated by some time T') and arrive at M non- > > simultaneously (but separated by some other time T). > > > > > > That means that M and M' agree with each > > > > > other on all non-simutlaneity events. > > > > > What? No. You mean that for some pairs of strikes M and M' will both > > > > say the strikes are nonsimultaneous? Yes, that's true, but the two > > > > observers will say there is a different amount of time between them.. > > > > But nevertheless they both agree that if M' sees two strikes to be non- > > > simultaneous then M will also see the same two strikes to be no > > > simultaneous. > > > Not necessarily. See the above. In one case out of all the ones > > possible, the light will arrive at M simultaneously. For the others, > > not. > > Yes necessarily. No pair of strikes can occur non-simutlaneously at M' > and occur simutaneously at M. > > > > > > I agree that M' and M will say there is a different > > > amount of time between them. > > > > > So the "agreement" is pretty shallow. > > > > No not shallow at all. It illustrates that M and M' agree on non- > > > simultaneity of same two events...this follows that M and M' will also > > > agree on simultaneity of the same two event and thus refute the SR > > > claim of relativity of simultaneity. > > > No, it certainly does not follow. Don't be a complete idiot. > > You are the idiot. There exists an infinite number of pair of strikes > arrive at M' non-simultaneously and these infinite pairs of strikes > will also arrive at M non-simultaneously. There is one pair of strikes > that arrive at M' simultaneously. This same pair of strikes will also > arrive at M simultaneously. Why? Because the speed of light is > independent of the motion of the ends of the train. > > Ken Seto > > > > > If they > > agree that two strikes are non-simultaneous but disagree on the time > > separation between those non-simultaneous strikes, it doesn't AT ALL > > follow that they will agree that another pair of strikes are > > simultaneous. There is no logic that would produce that statement at > > all. > > > Your brain is out of whack. > > > > Also they will agree that > > > simultaneity occur at different time in the train than on the track. > > > > > > That seem to violate the basic > > > > > tenet of relativity of simultaneity. > > > > > I don't know what you think the basic tenet of relativity of > > > > simultaneity is. > > > > Did you think that the basic tenet of relativity of simultaneity is > > > > that if one observer says two events are non-simultaneous, then > > > > another observer will say they are simultaneous? > > > > Yes RoS says that if M' sees two events to be non-simultaneous then M > > > should sees the same two events to be simultaneous....that's what RoS > > > claim. > > > No, it does NOT say that. > > > Stop making stuff up. > > What have you READ about what the relativity of simultaneity says? > > Cite what you've read, so that you can prove you've not just made this > > statement up. > > > > >If that's what you > > > > thought it said, you're wrong. It doesn't say that at all. > > > > Yes it does. > > > You are never going to understand relativity, Seto. Never. > > > You cannot think straight. Hopeless. Ken, you're never going to get this. Your mind is bent. > > > > Ken Seto > > > > > > Your assertion that there is one pair of light fronts that will arrive > > > > > at M" simutltaneously is irrelevant....why? because M" is not at the > > > > > middle of the train. > > > > > Yes, it is. > > > > > > It is true that there is one pair of light fronts out of the infinite > > > > > pairs of light fronts that will arrive at M' simultaneously but that > > > > > pair of light fronts will also arrive at M simultaneously....why? > > > > > Because the speed of light is independent of the motion of the ends of > > > > > the train. > > > > > A fourth grader can understand that and yet you call yourself a > > > > > physics professor. <shrug> > > > > > > Ken Seto. > > > > > > > It will also be possible to find a pair of lightning strikes such that > > > > > > they arrive at M' non-simultaneously and at M simultaneously. Just > > > > > > maybe not the pair you're talking about. > > > > > > > > Since there are an infinite number of pairs of strikes that can cause > > > > > > > the light fronts to arrive at M' non-simultaneously, does that means > > > > > > > that there are infinite pairs of strikes that M will see their light > > > > > > > fronts to arrive at him simultaneously????? > > > > > > > No. Just one pair. > > > > > > > Idiot. > > > > > > > Ineducable idiot. > > > > > > > Shamelessly self-immolating, ineducable idiot. > > > > > > > > Ken Seto > > > > > > > In case you thought you had some brilliant insight here, Ken, no. You > > > > > > are asking a 6th grade question.- Hide quoted text - > > > > > > - Show quoted text -- Hide quoted text - > > > > > - Show quoted text -- Hide quoted text - > > > > > - Show quoted text -- Hide quoted text - > > > > - Show quoted text -- Hide quoted text - > > > > - Show quoted text -- Hide quoted text - > > > - Show quoted text -- Hide quoted text - > > > - Show quoted text -- Hide quoted text - > > > - Show quoted text -- Hide quoted text - > > - Show quoted text -- Hide quoted text - > > - Show quoted text -- Hide quoted text - > > - Show quoted text -
From: artful on 27 Jul 2010 21:42 On Jul 28, 12:04 am, Hayek <haye...(a)nospam.xs4all.nl> wrote: > whoever wrote: > > "Hayek" wrote in messagenews:4c4ebce5$0$22935$e4fe514c(a)news.xs4all.nl... > > >> Inertial wrote: > > >>> Anyway .. none of that has much to do with the answer > >>> to Ken's re-statement of the same old train gedanken > >>> that has been dealt with by SR for almost a century. > > >> I find a lot of flaws in these "gedanken". For instance, > >> Einstein assumes that the event only takes place if you > >> see the lightflash of the event in your frame of reference. > > > Wrong > > >> Light to me, is only an imperfect carrier of > >> information, just as sound is. > > > Yes it is. Among other things > > >> With instantaneous communication, > > > No need. And by SR not possible > > >> and a correct > >> definition of time, > > > We have one > > Ok, time is what you read on a clock. I didn't say that > Then, what is a clock ? A device for measuring time > >> and there is no such thing anymore > >> as relativity of simultaneity. > > > So if you make up a different theory, then you don't get it > > It is not about "getting" it, it is abput expaining "it". Its neither that I was saying .. I was saying that if you make up a different theory, then you don't end up getting relativity of simultaneity. But that doesn't mean that such theory is valid .. it would have to predict the time dilation that we DO observe experimentally for a start. > > .. but does > > that theory actually work in reality? > > Of course, it just explains things differently. Not all theory explain things correctly. They may be different, but also wrong. You need a theory that gives you the time dilataion that we see experimentally. > In the expectation to make further progress, to enlarge > the understanding. Irrelevant if the theory isn't correct (ie doesn't predict/explain what experiment shows us). SR *does* predict/explain experiment > >> Then again, I do not agree with the block universe, and > >> accept the fact that the Now is the same everywhere in > >> the universe. Just the clocks, just measuring inertia, > >> measure higher or lower inertia, as an inertiameter > >> should do. > > > Clocks don't measure inertial .. they measure (or mark) time. > > Then, what is time ? A dimension like (but not the same) as space. What is space? > To me, time emerges from motion. Motion requires time for it to occur .. you have things backward. Anyway , your personal philosophy of what time means doesn't really make a scrap of difference to physics [snip irrelevance] > > Up to you, but unless you have good scientific ground, its just an > > unsupported opinion > > I have. What? All I've seen is nonsense about FTL .. no explantion for time dilation, and no reason given to reject SR. > >> Is it possible to have RoS in the conventional view, > >> according to you ? > > > RoS doesn't mean a block universe. > > That was not the question. It was exactly the question. Try reading > > Effect still follows cause. It > > doesn't alter the notion of every point in the universe having a present > > past and future > > That is not the conventional view, but rather the block > universe. No .. it IS the conventional view. You clearly don't understand either.
From: artful on 27 Jul 2010 21:43 On Jul 28, 4:35 am, Hayek <haye...(a)nospam.xs4all.nl> wrote: > Daryl McCullough wrote: > > Hayek says... > > >> In the latest Now, every object has a velocity, > >> setting direction and speed. > > > What does "velocity" mean, if not the derivative of > > position with respect to time? > > It is like deprogramming a hare khrishna or something. :-) > > Imagine a three dimensional space. Just three dimensions. > > Now imagine an object in it. > > Now let this object move , and normalize its speed 1. > > When a second object covers twice the ground as the > first then say it has speed 2. > > The position of the objects is called the Now. > > There is no past, no future, just the two objects and > their changing positions. > > No need to define time or have a time dimension. How can an object move (or any change occur) if there is no time? ANSWER: It can't. Once philosophical definition of time is "that which allows things to change".
From: Hayek on 28 Jul 2010 04:40 Daryl McCullough wrote: > Hayek says... > >> Imagine a three dimensional space. Just three dimensions. >> >> Now imagine an object in it. >> >> Now let this object move , and normalize its speed 1. > > What does "move" mean, if you don't have a notion of > time? Just change in position. And the rate of change in position does not have to rely on time, it can exist on its own. > > I know what *I* mean by saying "the object has moved". > It means that the object at one time is at a different > location than it was at an earlier time. That is a convenience approach for you brain. You remember the object in a, and it is now in b. There is only one object, and it is no longer in a. Nature does not do time. It just does motion. It is quite hard deprogramming your brain on this. But if you try hard, you will see that all we observe does not need time. Julian Barbour has about the same idea, but he calls it change. Now change and motion are not semantically the same, I understand change as a molecule forming a bond for instance, anyway Barbour does not explain what he means by change. And then he even does away with motion, as he renames and joins the time dimension �nd the many worlds interpretation of qm into "Platonia". The problem is that he wants to keep Mutual Time Dilation, and that is impossible without time dimension or "platonia". The question you need to ask yourself is : is what we perceive possible in a world with just 3d + motion ? Try to stay at Newtonian views first, and if you succeed, I will tell you how to add the relativistic stuff to this view. >>>> Caused by inertia. I suppose you could say that >>>> "time is a function of change of position". >>> That doesn't make sense. You can't say that position >>> has *changed* unless you have two different times to >>> compare those positions. >> These are only in your memory. That is playing tricks on >> you. Move a ball from a to b. > > What does "move" mean? You are in a 3d world, there are many positions. Just changing from one position to the other. Try to grasp that first, you do NOT need time for this. Then you could add the way things move, by adding inertia to the model. > You are engaging in circular > reasoning. To talk about "moving" a ball from a to b > means that at one time, the object is at a, and at > a later time, the object is at b. The fact that the object was in a, remains only in your memory, not in nature. The object has moved, period. It does not sit there anymore at time "a", except in your memory. And you could describe time "a" as "the past now when the object was in a. See, we used a position to describe "time", which emerges from motion and positions. But the "old" positions are gone, lost, only a memory or pictures remain. And these memories and pictures were also made of motion that captured the position of particles, and then remained conserved. > But that presupposes > that we already understand what "time" means. You want to order events with time. You have been thought so. Nature does not do that : events are ordered by inertia. An object has the move in a Newtonian way, it if it moves inertially through abcd, it has to go through a first, then b, then c, then d. Inertia does not permit it to go to c then back to b. (In qm this is possible, that is one reason I claim that inertia is missing there) Uwe Hayek. -- We are fast approaching the stage of the ultimate inversion : the stage where the government is free to do anything it pleases, while the citizens may act only by permission; which is the stage of the darkest periods of human history. -- Ayn Rand I predict future happiness for Americans if they can prevent the government from wasting the labors of the people under the pretense of taking care of them. -- Thomas Jefferson. Socialism is a philosophy of failure, the creed of ignorance, and the gospel of envy, its inherent virtue is the equal sharing of misery. -- Winston Churchill.
From: Hayek on 28 Jul 2010 04:56
PD wrote: > On Jul 27, 1:35 pm, Hayek <haye...(a)nospam.xs4all.nl> wrote: >> Daryl McCullough wrote: >>> Hayek says... >>>> In the latest Now, every object has a velocity, >>>> setting direction and speed. >>> What does "velocity" mean, if not the derivative of >>> position with respect to time? >> It is like deprogramming a hare khrishna or something. :-) >> >> Imagine a three dimensional space. Just three dimensions. >> >> Now imagine an object in it. >> >> Now let this object move , and normalize its speed 1. >> >> When a second object covers twice the ground as the >> first then say it has speed 2. >> >> The position of the objects is called the Now. >> >> There is no past, no future, just the two objects and >> their changing positions. > > OK, let's parcel this out a little bit. > > What you are doing is establishing a change from one Now state to > another Now state. Call the latter Now'. > > At the moment, you do not have any notion of speed. All you have is a > DISPLACEMENT. > The DISPLACEMENT of the first object (call it O1) is 1. The > DISPLACEMENT of the second object (call it O2) is 2. > > Now and Now' must be distinguishable so that you can declare a unique > state of O1 to have a single position (at Now) as opposed to two. If > Now and Now' are not distinguishable, then you have no unique position > identifier for any object. Fine. Only the first Now ceases to exist, actually there never was a now, it was and still is "the current position of all the objects" . > The first thing to notice is that you have declared unilaterally that > you can describe these states unilaterally and unambiguously. That NOW > and NOW' are labels that can be applied to both O1 and O2. You haven't > said so, but it's worth asking whether those labels are independent of > reference frame. > > Where time comes in, is the observation that certain repeatable > processes can be reliably compared, and that they will always produces > a common ratio of countable progress. For example, one process might > be the swinging of a pendulum of a certain length. Another process > might be the emptying of a can of water through a hole in the bottom. > And it is noted that, initiating both processes with label Now and > terminating at another label Now', it is observed that the can of > water has emptied once and the pendulum has swung 187 times. If you > repeat this, you find the same ratio. This comparison of processes is > what we mean by, and how we declare a measurement of, time. Excellently said. But that confirms my view that time emerges from motion. And what you describe is inertia. And that is why I say that a clock is an inertiameter. If inertia were higher , then your pendulum would swing slower, and the water would empty slower. On the Earth's surface inertia is practically everywhere the same. That makes clocks useful for comparing motion. > In particular, what it means is that we will make a particular choice > of a process, say the swinging of that pendulum, and we will declare > that a Unit Process, or if you like, a Unit of Time. Then all > processes can be compared to this (with certain stipulations of > locality and relative rest). > > Speed, then, is simply marking a DISPLACEMENT between Now and Now', > and finding the ratio of that displacement to the number of those Unit > Processes. A long text for what I said in one sentence : >> Now let this object move , and normalize its speed 1. Uwe Hayek. -- We are fast approaching the stage of the ultimate inversion : the stage where the government is free to do anything it pleases, while the citizens may act only by permission; which is the stage of the darkest periods of human history. -- Ayn Rand I predict future happiness for Americans if they can prevent the government from wasting the labors of the people under the pretense of taking care of them. -- Thomas Jefferson. Socialism is a philosophy of failure, the creed of ignorance, and the gospel of envy, its inherent virtue is the equal sharing of misery. -- Winston Churchill. |