Known physics defeated by simple puzzle?
in [Relativity]
|
From: Ste on 8 Apr 2010 20:28 On 8 Apr, 05:26, "Inertial" <relativ...(a)rest.com> wrote: > "Ste" <ste_ro...(a)hotmail.com> wrote in message > > > and what is > > simultaneous according to my definition may not be what you consider > > simultaneous. > > From what I see of your definition, it is equivalent .. and so also frame > dependent. This is absurd. My definition is, BY DEFINITION, frame independent. > Can you provide a more detailed description of your definition of > simultaneous, so I can validate whether it is, or is not. equivalent. Or if > it is differen,t in what way, and dos it actually 'work'. I've just said, what is "simultaneous" is "those events which would be simultaneous if information propagated instantly". And this is frame independent.
From: Inertial on 8 Apr 2010 20:44 "Ste" <ste_rose0(a)hotmail.com> wrote in message news:36d9ebde-7754-41d1-937b-4ca17cb3771c(a)g11g2000yqe.googlegroups.com... > On 8 Apr, 05:26, "Inertial" <relativ...(a)rest.com> wrote: >> "Ste" <ste_ro...(a)hotmail.com> wrote in message >> >> > and what is >> > simultaneous according to my definition may not be what you consider >> > simultaneous. >> >> From what I see of your definition, it is equivalent .. and so also frame >> dependent. > > This is absurd. I'm glad you see your absurdity > My definition is, BY DEFINITION, frame independent. What definition? If you mean what you say below, you simply ASSERT it is frame independent. >> Can you provide a more detailed description of your definition of >> simultaneous, so I can validate whether it is, or is not. equivalent. Or >> if >> it is differen,t in what way, and dos it actually 'work'. > > I've just said, what is "simultaneous" is "those events which would be > simultaneous if information propagated instantly". That makes no sense .. you've defined simultaneous in terms of simultaneous. Further, whether or not two events are simultaneous has nothing to do with the speed at which information about them propagates. THAT is one of you many misunderstandings about physics > And this is frame > independent. So you assert, with no logical argument .. but then, you are yet to give a non-recursive definition of simultaneity
From: Ste on 8 Apr 2010 21:59 On 8 Apr, 14:53, PD <thedraperfam...(a)gmail.com> wrote: > On Apr 7, 10:00 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > And what we really mean by "reference frame" is that > > > > certain real objects have defined mathematical values for their > > > > properties (like defining certain objects to be at rest, and facing a > > > > certain direction), and the values of all other objects are calculated > > > > in relation to that. > > > > > But certainly, there is no need to make reference to a "frame" in > > > > order to calculate a "relative speed" between two objects. > > > > Yes, there is. > > > Is there? (And I'm assuming we're disregarding SR). > > I'm talking about how nature works. If what you mean by "calculate a > relative speed" you intend to produce a result that corresponds to > something measurably verifiable, then yes, you do need to include > reference to a frame, because a measurable relative speed (or to use a > more carefully defined physics term, closing speed) is frame- > dependent. Now, if you wish to say, "I can certainly calculate > anything I want, regardless whether it has any relevance to anything > measurable, and I can certainly choose to do so in a way that is frame- > independent," then you are certainly free to do that, just as you are > free to suppose everlasting souls and the presence of angels. It's > just that there's no scientific interest in doing so. The beauty of theory Paul is that you can perform measurements without involving (or having reference to) any observer. You're quite right that, in real experiment, the observer himself must have a velocity with respect to the two objects of interest. But the point is to isolate and iron out the observer effects, and leave only a "real" remainder. So for example, if you're talking about the frequency of an audio source, then you isolate the Doppler effects and correct for them, leaving the "true" value for the source frequency. > > > And it turns out that the relative speed between two > > > objects as *measured* in different reference frames, is frame- > > > dependent. Observationally. Whether you think this is nonsense or not.. > > > And of course, I do think that. > > Then you should be encouraged to do some measurements. > Again, the fundamental issue is that you seem to insist on believing > in the unverifiable reality of certain things because those things > make sense to you. No, it's simply because I hold that not everything "real", and of relevance, can be directly measured and verified. > And you are more willing to believe in those things > than you are in statements that are contrary but confirmed by > measurement. As long as you do that, then you are simply favoring > faith over evidence, and that has nothing to do with science. It's not about "faith over evidence". The evidence is meaningless without interpretation. The real question, which is the same as it ever was in human history, is *how* we are to interpret evidence, not *whether* we are to interpret it.
From: Ste on 8 Apr 2010 22:07 On 8 Apr, 15:02, PD <thedraperfam...(a)gmail.com> wrote: > On Apr 7, 10:21 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > Remember the ladder is moving relative to the barn. > > > How does one determine that the ladder is contained completely inside, > > > exactly? > > > By shutting the doors at the same time, of course. > > Yes, indeed, this is a crucial ingredient. And of course if the doors > were not shut at the same time, then we would not say that the first > object fit inside the second object, would we, even though otherwise > the observations would be the same? That is, if the front of the > ladder were inside the barn (having verified that it passed through > one but not the other door) when one door was shut, and the back of > the ladder were inside the barn (by the same verification) when the > other door was shut, this would be no indication that the ladder fit > inside the barn, right? Especially if the doors were not shut at the > same time. Indeed. The question, really, is not whether the ladder fits inside when the doors are actually shut, but whether it *would* fit if they *were* shut. As I say, I don't think we need to discuss extensively what "fitting" means - but for completeness, it simply means whether the full extent of the ladder could be at once contained within the confines of the barn. > So, jumping to the chase, if in one reference frame, it is established > that the doors were shut at the same time, then the definition of > "fitting" inside the barn would have been met, and the ladder would > have fit inside the barn in that frame. If in another reference frame, > it is established that the doors were not shut at the same time, then > the definition of "fitting" inside the barn would not have been met, > and the ladder would not have fit inside the barn in that frame. So, > you see, it is entirely possible -- and indeed we would be forced to > this conclusion -- that the ladder fits in the barn (by virtue of your > own definition) in one frame and does not fit in the barn in another > frame, provided that we can establish that the timing of the doors > being shut depends on the frame. Yes, but this is a contradiction in reality, so the only other explanation is that perhaps it *appears* to do this, but does not actually do so. And of course, my money would be that nothing changes real length at all, and that the appearance of this is an illusion that can be explained somehow in terms of the behaviour of the electromagnetic interaction (possibly combined with a misinterpretation of what relativity actually describes, and an ignorance of the mechanisms underlying the effects of relativity).
From: Inertial on 8 Apr 2010 22:08
"Ste" <ste_rose0(a)hotmail.com> wrote in message news:b7fb085d-5d0b-43d2-b66c-6fb12449aee8(a)h27g2000yqm.googlegroups.com... > On 8 Apr, 05:49, "Inertial" <relativ...(a)rest.com> wrote: >> "Ste" <ste_ro...(a)hotmail.com> wrote in message [snip a lot of unnecessary waffle and off topic meadering] >> >> If you and I are relatively moving. I would say that I am at rest and >> >> you >> >> are moving faster than me. You would say YOU are at rest, and I am >> >> moving >> >> faster than you. That is not a contradiction. >> >> > I wouldn't necessarily say that. >> >> you would if you didn't lie > > No, because I could use the formulation that followed below... [snip] > How am I avoiding the question? Obviously, by not answering how you see you own motion relative to you. Do you deny that you consdier yourself as at rest, whereas I consider you to be in motion? Velocity is frame dependent. Get used to it. And according to your defintion, that makes velocity not 'real' > I've just given you a statement that > does not refer to a frame. Only because you are assuming a geometry where such a statement is the same in all frames. One can make statements about frame-independent things independently of the frame. Noone said you can't You problem is what you consider to be frame independent *isn't* when you are talking about the real world and SR [snip] >> And what would you say about your own speed relative to yourself? > I wouldn't say anything about it. Avoiding the question again [snip] >> Of course we are .. that is implicit in talking about what is measured >> relative to the frame. I think you think that 'an observer' means there >> has >> to be a person physically there. > > No I don't think that. I often talk of observing "as though I were > God", so I clearly don't hold that an observer actually has to have a > physical presence on the scene. Good. >> > If you're asking >> > whether something is at rest wrt to another object, then that is frame >> > independent. >> >> Indeed it is. A closing speed of zero is one that all observer will >> agree >> with. > > That's something else to add to the post-it note labelled "points of > agreement". Good. And please note then that when we generalize and say closing speed is frame dependent, that is not invalidate by there being a specific speed, or particular choice of frames, where two or more frames agree. >> >> >> > We are talking about the object in question >> >> >> > having a speed of 50kmh relative to one object, and a speed of >> >> >> > 100kmh >> >> >> > relative to a *different* object than the first. >> >> >> >> But it is the ONE object having the two velocities at the same time >> >> >> .. >> >> >> depending on who is measuring them >> >> >> > No, the "one object" doesn't have "two velocities". >> >> >> Yes .. it does. It has an infinite number of velocities. >> >> > This is just mathematical waffle. >> >> No .. it is physics and common sense > > It's not common sense at all. It is common sense. > Common sense is that things can be > described in infinitely different ways, Irrelevant > but no one says it is "common > sense" that states or relationships are *really* different just > because you're using different numbers to quantify it. You are misrepresenting again. I am not saying the relationships are different because the number are differnet. The numbers are different because the relationships are different. You have it backwards. Of course it is really different. A velocity of 100km/hr is REALLY different to one of 50km/hr > After all, I > could describe a loaf of bread on the table in a thousand languages, > and the load wouldn't change its "real" qualities even once. Irrelevant > Or we're you making some sort of point about continuous variability? No >> >> There is no illusion. You just cannot seem to get it into your head >> >> that >> >> you can get different values for the same 'thing' from different >> >> frames >> >> of >> >> reference. >> >> >> THAT is your major problem here. >> >> > I can understand the notion of getting "different values". >> >> It doesn't sound like it , as you argue against it every time >> >> > I can say >> > the room is 20 degrees C, or what, 68 degrees F. >> >> Totally different concept. Gees. >> >> > But I'm describing >> > the *same* real temperature, >> >> Yes .. so not a good analogy >> >> > but with different numbers (because I'm >> > referencing different scales). The problem here is that the "real" >> > relationship, of "fitting", is being described in two mutually >> > exclusive ways. >> >> 'fitting' is frame dependent . .and so, by your definition, not 'real' > > Indeed, but it's not that "fitting" is unreal, It is by your definition. Because it is a frame dependent notion. > but that it is "frame > independent", It isn't. It is frame dependent. You insisting that it isn't doesn't make it so. > and hence quite real. Nope > The mistake is yours in describing > it as "frame dependent". No .. your mistake is saying it is frame independent. it is clearly frame dependent as it relies on simultaneity, which is frame dependent. It looks like this is a stumbling block that you cannot get past. until you can, there is very little more that you can learn and understand >> > Simultaneity >> > is itself an inherently relative measure (i.e. you're asking about the >> > time interval *between* two events). But that measure ought to be >> > invariant across frames, in the same way it is for distance and >> > velocity. >> >> There you go .. saying what 'ought to be'. Nature doesn't care about >> what >> you think it ought to be. Trying to then model nature assuming that what >> ought to be is true will fail. > > I wish you'd stop invoking these irritating cliches. They are relevant. If you are irritated by them ,then change your behavior. > When I say "ought > to be", I mean "ought to be, following from other natural principles", It doesn't.. not by what we know about how nature behaves. > not "ought to be merely because I say so". No .. because you refuse to consider that nature doesn't work the way you think it does. |