Known physics defeated by simple puzzle?
in [Relativity]
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From: paparios on 9 Apr 2010 15:50 On 9 abr, 15:39, Ste <ste_ro...(a)hotmail.com> wrote: > On 9 Apr, 15:24, "papar...(a)gmail.com" <papar...(a)gmail.com> wrote: > > > > > On 8 abr, 21:59, Ste <ste_ro...(a)hotmail.com> wrote: > > > > On 8 Apr, 14:53, PD <thedraperfam...(a)gmail.com> wrote: > > > > 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. > > > Let us explore this for a moment, in the form of a very simple > > gedanken (I have used this on several occasions). No frame of > > references are needed. > > > You are aboard a space ship in intergalactic space (meaning you are > > very far away from gravitational effects). While in this condition, > > you do not feel any force acting on your body (you are weightless > > floating inside your space ship). Also, you have aboard a small window > > and you are looking through it and, of course you see just a complete > > darkness, without galaxies, stars or any other stellar object in your > > surroundings. > > > Suddenly, you start to see, far away, an object which, with the help > > of a telescope, you identify as another space ship (by its use of > > flashing red and green beacons). The object appears to be approaching > > your location. Now, which of the following assertions is true and > > which is false. > > > a)Your space ship is not moving and the other space ship is > > approaching at a speed v (closing speed measured with a laser gun). > > b)Your space ship is moving at a speed v and the other space ship is > > not moving. > > c)Your space ship is moving at a speed 0.4v towards the other space > > ship, which itself is moving at a speed 0.6v towards you. > > d)There are infinite solutions of relative speeds satisfying the > > observation. > > e)All of the previous assertions are true, since speed is a frame > > dependent variable. > > > So for escape from this multitude of compatible solutions, you have to > > choose one of them, which is equivalent to select one of the frames of > > reference to calculate the different physical quantities. So for you, > > it is easier to select a given point (x0,y0,z0) and given axes (x,y,z) > > somewhere inside your ship, as that frame of reference which allows > > you to discard all alternatives except (a). > > I would suggest a sixth solution. That the only "true" and "real" > statement that can be made, from the evidence available, is that you > and the other spaceship are converging positions at a relative speed > of 'v'. Which in itself is choosing by de facto a frame of reference: the one related to the laser gun used to measure the closing speed. That is, you are choosing location (x0,y0,z0) and given axes (x,y,z), according to the orientation and location of your laser gun. This is not a new sixth solution but a different wording of solution (a). Miguel Rios
From: PD on 9 Apr 2010 15:52 On Apr 9, 2:32 pm, "Sue..." <suzysewns...(a)yahoo.com.au> wrote: > On Apr 9, 10:57 am, PD <thedraperfam...(a)gmail.com> wrote: > > > > > On Apr 8, 9:09 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > On 8 Apr, 15:10, PD <thedraperfam...(a)gmail.com> wrote: > > > > > On Apr 7, 10:32 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > > It's awfully difficult to misinterpret the numerical value of a > > > > measurement and whether it agrees with the numerical value of another > > > > measurement. > > > > No, because if I say relative to me A is moving at 10kmh and B is > > > moving at 20kmh, and you say that relative to you A is moving at > > > 20kmh, and B moving at 30kmh, then despite the numerical difference of > > > speeds we both agree about the movement of A relative to B. > > > But that is not what happens. > > For example, if I see a car traveling west at 10 kmh, and a car > > traveling east at 35 kmh, then you have the expectation that, to a > > passenger riding in the car traveling east, the other car is traveling > > 45 kmh west. > > But in fact, it is not traveling at 45 kmh west to a passenger in that > > car. > > It is traveling at something close to that, but only approximately. > > ========================== > > > > > The bottom line is, the basic sum rule you've been taught for relative > > velocities is a LIE. > > << The main types of particle combinations used at RHIC > are p + p, d + Au, Cu + Cu and Au + Au. The projectiles > typically travel at a speed of 99.995% of the speed of light > in vacuum. For Au + Au collision, the center-of-mass > energy \sqrt{s_{NN}} is typically 200 GeV > (or 100 GeV per nucleus); >>http://en.wikipedia.org/wiki/Relativistic_Heavy_Ion_Collider Yes, and the energy adds. The velocities don't. You DO know the difference, don't you? No, I suppose not. > > > > > PD > >
From: Ste on 9 Apr 2010 16:00 On 9 Apr, 15:45, PD <thedraperfam...(a)gmail.com> wrote: > On Apr 8, 8:59 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > 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. > > This is not removing an "effect". By "true" source frequency, you are > simply stating what the frequency is as observed in the reference > frame in which the source is at rest. No I'm not. As I started out by saying, the frequency of the source can be measured directly by Ladar, or even high-speed cameras, even when the observer is moving relative to the source. And for sure, if you were at rest relative to the source, then the microphone measurement would accord with the Ladar measurement. But the point is that the Ladar measurement is the same *even when you are moving relative to the source*. The conclusion to reach from this is not that the Ladar is merely measuing the "rest frequency", but rather that the frequency measured when at rest is the *real* source frequency, and if one wants to measure the source frequency with sound, then one must account for the dynamics of sound when trying to ascertain the source frequency from the received frequency. It is the same with this length contraction. Unless the object is mechanically contracting, then the explanation *must* lay in the dynamics of the electromagnetic interaction *between* the two objects. There is no other explanation that has been offered, except to assert plainly (and unconvincingly) that it is not due to the interaction. > There is no "true" frequency > other than that. By "isolating the Doppler effects and correcting for > them," what you are doing is switching from the reference frame in > which the source is moving to the reference frame in which the source > is stationary. There is nothing in that which is separating "real" > from "distorted perception". It is simply recognizing the frame > dependence of the frequency and choosing a particular frame and > LABELING it (arbitrarily) as the "true" frequency. I didn't label it as the "true frequency". I labelled it as the "true value for the source frequency", which is different from the apparent value. > > > > > 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. > > As would be claimed by people who hold that they can infer the > existence of angels from other evidence, even though angels themselves > cannot be directly measured and verified. Indeed. As I've said, I would merely affirm my naturalistic axioms. There is no useful distinction between science and religion, *except* that science necessarily rules out the supernatural as a cause or explanation for anything. To beat about the bush, and pretend that science is somehow being objective or has no axioms, just hobbles the further development of science and indeed means that science is lying to itself all the time.
From: PD on 9 Apr 2010 16:03 On Apr 9, 2:39 pm, Ste <ste_ro...(a)hotmail.com> wrote: > On 9 Apr, 15:24, "papar...(a)gmail.com" <papar...(a)gmail.com> wrote: > > > > > On 8 abr, 21:59, Ste <ste_ro...(a)hotmail.com> wrote: > > > > On 8 Apr, 14:53, PD <thedraperfam...(a)gmail.com> wrote: > > > > 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. > > > Let us explore this for a moment, in the form of a very simple > > gedanken (I have used this on several occasions). No frame of > > references are needed. > > > You are aboard a space ship in intergalactic space (meaning you are > > very far away from gravitational effects). While in this condition, > > you do not feel any force acting on your body (you are weightless > > floating inside your space ship). Also, you have aboard a small window > > and you are looking through it and, of course you see just a complete > > darkness, without galaxies, stars or any other stellar object in your > > surroundings. > > > Suddenly, you start to see, far away, an object which, with the help > > of a telescope, you identify as another space ship (by its use of > > flashing red and green beacons). The object appears to be approaching > > your location. Now, which of the following assertions is true and > > which is false. > > > a)Your space ship is not moving and the other space ship is > > approaching at a speed v (closing speed measured with a laser gun). > > b)Your space ship is moving at a speed v and the other space ship is > > not moving. > > c)Your space ship is moving at a speed 0.4v towards the other space > > ship, which itself is moving at a speed 0.6v towards you. > > d)There are infinite solutions of relative speeds satisfying the > > observation. > > e)All of the previous assertions are true, since speed is a frame > > dependent variable. > > > So for escape from this multitude of compatible solutions, you have to > > choose one of them, which is equivalent to select one of the frames of > > reference to calculate the different physical quantities. So for you, > > it is easier to select a given point (x0,y0,z0) and given axes (x,y,z) > > somewhere inside your ship, as that frame of reference which allows > > you to discard all alternatives except (a). > > I would suggest a sixth solution. That the only "true" and "real" > statement that can be made, from the evidence available, is that you > and the other spaceship are converging positions at a relative speed > of 'v'. From the information that is available, which is from one of the spaceships, that is a true statement. The interesting question comes, then, from a second observer that sees the two ships approaching from opposite directions. This observer sees one ship approaching at a measured v1, and the other approaching at a measured v2. What you might expect is that v1+v2 = v. However, this turns out experimentally not so. v1+v2 will end up being a number greater than v. More importantly, this second observer has nothing from his measurements that would indicate that the value v corresponds to anything pertaining to the two ships. So here we have a problem. We have an observer on one of the ships saying that the closing speed between the two ships is v. We have another observer not on either ship that says that the closing speed between the two ships is a number different than v. Which one would we take to be right? And why? I notice that your statement is stronger than just saying the closing speed is v, as measured from one of the ships. You are in fact saying that the value v is the "true" and "real" closing speed is v. This obviously gives priority to this observer over the one that I just mentioned. But why is such priority given? PD
From: Ste on 9 Apr 2010 16:11
On 9 Apr, 15:54, PD <thedraperfam...(a)gmail.com> wrote: > On Apr 8, 9:07 pm, Ste <ste_ro...(a)hotmail.com> wrote: > > > > 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. > > And again, the main thing to remember is that the ladder is moving > relative to the barn. I didn't forget it, and it is indeed obvious that, with a moving object, the doors could not remain shut indefinitely without a collision. > > 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. > > I completely disagree. This is where the precision of the definition > is important. It is only by waving hands generally and dismissively > about what a word *means* that you afford yourself enough vagueness to > suppose that "fitting" should be a frame-independent concept. As soon > as you try to be precise about what "fitting" means, you learn that > any precise definition quickly leads to incompatibility with frame- > independence. So the conclusion is that if the only way you can secure > the frame-independence of the concept is by being vague and loose with > what the concept actually means, then you've only succeeded in fooling > yourself with an inherently inconsistent concept. As I've said, I think the concept of "fitting" is quite obvious - it is surprising that physicists can not understand the meaning of this ordinary concept. And as I've said, the definition can be taken as the one I gave above. I suspect the real disagreement is not on the word "fitting", but, once again, about the concept of "simultaneity". > > > 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 again, what we would have to do is to clearly define what > simultaneity *means*, so that we can determine whether in fact the > frame-dependence of the timing of the doors is real. We've already > determined that the *reality* of "fitting* hinges precisely on this > statement of simultaneity, and so the question simply shifts to the > *reality* of simultaneity. Indeed. And as I've argued, while I accept that no information in the universe *does* propagate instantly, when talking of simultaneous, we must talk about what would be simultaneous if information *had* propagated instantly. Otherwise, we get a definition of simultaneity that is entirely subjective, and meaningless - that is, we get a situation where John, who ate breakfast at 9am, says it happened at 9am, and as for Jack, whom John told about eating breakfast, Jack says the breakfast was eaten at 7pm (i.e. when Jack finally found out that John's breakfast had been eaten). > > 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). > > The "explained somehow" is the part that gets into vigorous hand- > waving. It is an appeal to "Surely there is something -- *anything* -- > that could account for this other than having to appeal to > relativity." It is not hand-waving Paul. The electromagnetic interaction is where I remain convinced the explanation lies, for all the reasoning we've discussed at length previously in this thread. > That's all well and good, but in the absence of a > concrete alternative, there is the fact that relativity does do a > proper job of explaining it, whether you find it distasteful or not. > When there is something put forward that competes as well as > relativity, then surely it will be deserving of consideration. No one says that relativity doesn't account for what is *observed*. The question is whether the observation reflects reality - i.e. whether the observation can be taken at face value, or whether it requires a layer or interpretation or "correction". |