altergnostic

I have never been truly convinced of any gravity hypothesis, and as far as I am concerned, there has never been a single realistic model in history. We went from pulling force at a distance to matter curving the geometry of spacetime, which has great predictive power but still zero mechanics, it is purely abstract. We have come to conclude that nature may perhaps only be accessible through abstract models and should quit trying to visualize all interactions and causes, because we are not equiped to understand nature intuitively. I resist that approach and rather believe that it is our models that are not well equiped to explain nature, and cling on to the hope that we can change this someday. I would not be too surprised if the waves are never detected (I still don't buy the higgs detection is the higgs boson - with the predicted properties of the particle - but let's wait and see). I think it was Maxwell that propesed the dimensions mass are L^3/T^2, so the dimensions of gravity (L^3/MT^2) effectively cancel out and it becomes just a number. A Miles Mathis (taken as a crank by a large portion of the scientific comunity) used this to express all force in terms of length and time and dispense with any idea of mass. "The idea of acceleration already includes the idea of impermeability" he said, since you need a boundary to determine acceleration (or the shape of a rigid body, for that matter). His idea was that gravity was a reestatement of mass which is a reestatement of inertia - they are all effects of a single property: expansion. He proposed that all bodies expand at the same rate, so all proportions are kept constant. He didn't like this idea and used it as a mathematical tool in the end (reversing all gravity vectors by the equivalence principle). I don't think that this expansion has any material meaning, but the dimensions of mass may point us in a new direction indeed, one in which gravitational waves play no part, if they end up being falsified.

By your analysis on the circular orbit, relativistic and classical doppler yield the same number, but it's because you used orbital speed, and that requires that we know the rate in the pulsar's rest frame indeed, otherwise we are left in the dark. But my idea was to set the nearest and farthest positions of the orbiter from the earth as v=0, since we are only interest in relative velocity in the x direction. By that token, a circular orbit's velocity varies just as well. Classically, the approaching and receding pulse rates should offset perfectly, but not relativistically, since linear relative velocity would slow down the pulse rate on both halves of the orbit - and that slowing down would range from 0 when v=0 to maximum when v=max. What you did was a comparison of maximum positive to maximum negative velocity, and by that analysis both pulse rates should offset indeed, since time dilation due to linear velocity would decrease both sides' pulse rates by the same amount.

Yes, I get that. I thought you were talking about the effects of time dilation due to linear speed only, I know doppler causes both shifts. Anyhow, so basically we can't measure this system with enough precision to analyse this effect? Do you know of any binary system that does?

Wait, what? t=gt' implies a redshift for both halves of the orbit, since the in gamma is a magnitude not a vector, that's why it's dilated and not contracted, a blueshift would be a contraction. (I am talkng abou the isolated effects of linear velocity here).

I didn't say "no time dilation", I meant no time dilation proportional to speed (magnitude) independent of direction (vector). Wait, you are using orbital velocities, aren't you? Those are relative to the center of gravity. Shouldn't we use numbers relative to earth? I mean: Set the conjunction alignments to v=0, since there's no motion away or towards the earth at these positions, and then compare the pulse period (time) for the receding and approaching halves of the orbit. Both should show a redshift due to relative velocity time dilation, but there's no indication of it (as far as I can see). Wouldn't this be the right approach?

Binary pulsars are often used to test predictions of GR, namely, the possibility of energy loss due to gravitational waves. But we never see any analysis of SR's predictions, although it is an extremely potential source of empirical data on time dilation due to velocity as well, since during the entire orbit the relative speed between earth-pulsar is variable. Pulsars are near perfect, incredibly stable clocks (each pulse is a tic), and we can observe the doppler shift and isolate time dilation effects due to gravitaty and velocity. It turns out that there's no indication of time dilation due to speed independant of direction (or so it seems). I've heard about this before but never came across actual data, until yesterday. Scroll down ro figure 5. http://www.cv.nrao.edu/course/astr534/Pulsars.html What do you make of this?

I like this kind of question, sometimes we forget what we don't know. We know that an electric current is made up of electrons - it is basically electron flow - but what makes up the magnetic field? And what the heck is charge? We know how a charged particle behaves and interacts with other particles, but what is + or - about it? Or rather, what motion/property/interaction/particle/state makes it negatively or positively charged? And what gives mass to matter is also an amazing question. What is mass? What gives matter impermeability and solidity? What does mass do to generate gravity? How does it pull (newton) or deform spacetime (gr)? How is mass and inertia related? What is it about mass that makes it resist change? I think it was Maxwell that made a dimensional analysis on mass and found that it can be decomposed into M = L^3/T^2. This volume over time squared, basically - the eq. is m = 2(r^2)s/t^2). What accelerates about mass? But back to magnetism, how does it create a pull? I would assume that both the electrical and magnetic fields are generated by the same (more) fundamental cause, which may be related to whatever it is that physically makes up the magnetic field - photons? Maybe a photon is not really a point particle (likely... a point should have no properties, since it is just a coordinate, a distance from an origin, a 0 by itself) and someday we'll find that it has mass and size and that it is the motions of these photons that cause the effects we see. And then we will ask what makes the photons move, why do they always move at c, yada.

I see, so indeed the table example shows that symmetry is not necessarily related to order/dirsorder, I agree (although I don't see how this relates to energy production). Now, water is more symmetric than ice, period? Shouldn't the configurarion matter? Ice may be frozen into a very symmetric finite group. And speaking of symmetry and groups, the mathematical (or geometrical, really) definition of symmetry, and the distinct groups in which systems can be divided into, are just as abstract as human taste. It is a grouping based on *preferred choice*. We decide what parameters are important. It is a theory of categorizarion, which aids greatly to simplify some problems, but unless the parameters are assigned to physical properties, we can't talk about energy production. Is a cube more energetic then a spiral? Is left less energetic than right? But when applied to a physical system, we must state exatcly what about a system is symmetric. It could be the shape, the energy potentials, charge distribution, surface patterns, weight distribution, motion patterns, etc. What about water is more symmetric than ice? Are you saying that water is absolutely more symmetric than ice, no matter what parameters we analyse, in whatever condition? Is the difference in symmetry between "hot" ice under great preassure and "cold" water in empty space related in any way to the potential energy production of each, or is it preassure and temperature that are directly related to energy? My point is. Symmetry, in itself, is abstract math, not physics. It has mathematical value, but only by applying it to the right parameters will you be able to use the math in your energy production project, and if that's the case to begin with, you'd have to study the physical properties themselves before working with symmetry. In any case, symmetry is no energy source, nor is fundamentally related to it. Only the assigned physical properties can produce energy, and these can be arbitrarily chosen, allowing us to define it such that less symmetric systems become either less or more energetic than more symmetric ones. Furthermore, two systems can have, for example, different spatial geometries and temperature distribution, either one of them being more or less symmetric than the other one depending on our choice of parameters, divorcing symmetry from entropy completely.

Yes, precisely. I was trying to translate what I thought was the OP's logic. He is probably considering the dilated time and assuming it will cause distortion.

The logic for a swirl is that the outer sections of the body would lag behind the inner ones, like a drain, where water closer to the center spins relatively faster than water further away. The first post was clear enough. I would only add two things: Time dilation due to velocity is frame dependant, meaning, the surface would see the center time dilated due to velocity the same amount as if measurements were done the other way around. Another problem is that the body is spinning, so the frame is not innertial. Any curve already represents an acceleration, as spin does. I'd say that, if the rotation is applied from the center, you don't need relativity to cause a swirl. From any point, really. Torque, you know.

My god... The table example is classic, every time I read it I think it must be a joke. Of all the analogies to physical processes, this one is by far the most ridiculous. The fact that people used left or right glasses doesn't change any physical parameters, the number of glasses is the same, heat is the same, weight is the same, etc. Left and right, or direction, are purely relative. And to state that water is more symmetrical than ice is nonsense. Water molecules move faster, but take a snapshot of either one and symmetry is purely visual, relative, and a matter of taste. Again, it is not symmetry that matters, it is the simple fact that water molecules move around more than in ice, hence, more energy. Adding energy, in this case, is adding heat and motion, not adding symmetry! You can't add symmetry to produce energy just like you can't add perspective to produce energy. The words don't even make sense. This is utterly incoherent. If my on and off switches were not enough, and this table exercise makes sense to you, I quit.

We measure how matter interacts with matter due to gravity, we don't measure how gravity interacts with matter, only how matter interacts with gravity. And we calculate how spacetime interacts with matter, but the curvature of spacetime can't be measured directly, it's geometry is calculated from the measurements we do on matter. In other words, spacetime geometry mathematically models how massive bodies affect other massive bodies to generate the effects caused by gravitation. Interesting. In this sense, gravity is a bit like the aether. We thought the aether was the cause of some observations, but couldn't detect it. Later on we managed to explain our observations without the concept of an aether. Maybe someday we will have a theory that explains what we observe without spacetime curvature or any field whatsoever.

So, your clock is or isn't indeed slower because blackhole. I see. What a great way to address the question! I have to admit it was funny, though. My god! What's that behind you??? (gone)

Deal. But still, I don't think that's the kind of symmetry that is being related to energy production here. A vortex out of an exhaust does not show that kind of objective order-disorder relation, right? Actually, no deal. What is the physical difference between <<<<< and <<<<>? The fact that five arrows in vaccum point to the left and that four point to the left and one to the right doesn't physically change anything. This is still a subjective impression, and reality couldn't care less. The switches example are different because their positions are implicitly assigned to different physical processes (like on and off current flows) and 4 electric currents is physically very different than 5 electric currents. But the positions of the switches themselves do not matter. For instance, if one of the five switches is upside down, 5 ups = 4 ons and 1 off, while 4 ups and 1 down = 5 ons. Which one is more symmetric or more ordered? You see what I mean? It is the physical processes that matter, not our judgement of order and disorder. 5 switches = 5 switches, their relative* positions or orientations by themselves have no effect on physical quantities. *this should ring a bell.

Hi. Order and disorder are not physical properties, but personal taste. You can say that 123123123 is ordered just like 111222333. Which one has the symmetry broken? Is polar magnetization more ordered than null magnetization? These are very abstract ideas, as you point out. You can call the same configuration ordered or disordered, depending on your definition of order. Using order and disorder as the theoretical basis for new forms of energy production sounds odd. Would you rather start working on a hypothetical solution to use the energy produced in some physical process by studying order and disorder or by studying the mechanics involved? Every physical process transforms energy. It is just a matter of studying ways to tap into such potential energy sources. I see no need for overly abstract ideas.

Of course there's the idea that the big bang is only apparently our time zero, but that the universe expands and contracts cyclicaly. But if there is really a zero time, causality must surely be violated, and I don't see how this is possible, not even with a godlike act of creation, because if god exists before the big bang, then the big bang is not the time zero and we can still ask what caused the existence of god and in that time zero we would need another act of creation. Maybe we might use a more practical notion of time to think about this. The way we have been talking about it, it might seem that time is an intrinsic property of the universe, but operationally, we only measure time by comparing subsequent states of matter or energy, just like a pendulum clock. We must compare the state of something in space with a following state of the same thing in space to determine any time interval and define what is a unit of time. In that way, time IS causality. Not only that, it is not a

If you want to keep c constant, then there's no lateral component. But then you must redefine the magnitudes of the units of length and time, so that x/t=c even though x is presumably larger. That's what the lorentz transformations do, but back when they were developed, it was assumed that light moves at c wrt the aether.If you add a lateral component you have violated the constancy of the speed of light postulate, and then you have to explain why it disagrees with experimental evidence here. My point is that experimental evidence says nothing about a beam that doesn't reach the observer directly, as far as I know, and I would like to know if there's any attempt to measure the speed of light in a moving frame, where the light beam being meadured is not directly detected by the observer.

The light-clock thought problem is used to demonstrate time-dilation. From the diagrams, in addition to the accepted assumptions, we can derive the time transform. Here's a typical diagram: http://galileo.phys.virginia.edu/classes/252/srelwhat_files/image017.gif It has always bothered me that it assumes we, as observers in the moving frame, actually see the beam bouncing between mirrors, but we don't. Neither the relative position of the observer nor the process by which we observe the beam are ever clear. Also, the diagrams seem to conflate an observer at the origin of a moving frame with an absolute frame in relative motion - the aether. Let's assume the light-clock moves to the right and the beam+mirrors can be described by a right triangle ABC, where A is the point of emission from the bottom mirror at T0, B is the point of reflection on the top mirror at T1, and C is the position of the bottom mirror at T1. The origin is at A and the right angle at C. How do we, as observers in relative motion, get the times and positions of the beam AB? If we were trying to diagram the beam in the aether frame, we could say that, as the beam moves through the aether, it describes AB at c by direct contact, but MM showed we can't check this assumption. We, as observers, would not see such a path. We wouldn't see the beam at all: it goes from one mirror to the other, but where are we in the diagram? We have no defined position yet. If we are not in line with the path of the beam, we can't observe it - we only see light that reaches us directly. Let's place the observer fixed at the origin A. As the beam moved towards B, he has no way to keep track of the beam's position. That's why we always measure the speed if light with a round trip. As it is, the light clock diagram works only by assuming that the path AB would be described at c for the observer, but the observer doesn't even see that beam, let alone know specific coordinates. We can update the setup so that the observer at A receives the beam's coordinates at B with a signal from a stationary emitter placed at B, but if we want to be really rigorous, we must assume c only applies to this signal, as seen from A. We must, because experiment shows that. But experiment doesn't show that an undetected beam, emitted from a moving source and travelling in an arbitrary direction, would also have an observed speed of c. Furthermore, everywhere we have c in SR's transforms, it applies to detected light - light from the observed event that reaches the observer directly. Do you know of any experiment that measures the speed of such a transverse beam? Is there any experimental evidence that shows that light travelling in the rest frame at c would also describe its path at c relative to an observer in relative motion?

I was not aware you were talking about the big bang. When you said "outside" I implied "off limits". The Big Bang is just a theory, and before the bang the theory has no way to account for anything. The model limits itself to the big bang, anything else is speculative. Since causality was never falsified, I rather keep it. You can't arrive at explosion without energy (or any other hypothetical cause). But the Big Bang model has no way to account for anything prior to the bang. I personally don't care much for the theory. Now, if there's something before the bang (presuming it happened at all) it is part of existence, so existence=0 does not apply. The reasoning you are pursuing can only yield two conclusions: infinite regression in time (no beginning, no first cause) or a violation of causality. I'd bet on the first option, but there's just no way to verify any of this, so it ends up being a purely philisophical discussion. We could apply Occham's razor here, where a "beginning" of the universe has to be explained with a multitude of assumptions while the "eternal" universe gets around them completely, and the only assumption would be causality - which is still unfalsified.

Maybe its a good idea to briefly reestate the point of this thread, since there was too much digression.

What do you mean by within and without?Without a universe (existence=0) there is no energy because there is nothing. Outside the universe... well, if there's something beyond the limits of the universe, then the limits were set in the wrong place. Where did you get the notion of energy within and without the universe? Could you elaborate? Also, the fact that we don't know the cause of an effect doesn't mean it doesn't have a cause, but I am not sure what effect you are talking about. Energy (or it's existence) is not an effect, just like matter is not an effect. Energy transfer is an effect.

If it is the spacetime metric that allows the field equations to spit out equations of motion, Minkowski must have something to do with it. If this is so, I would like to know specifically what step in his derivation is the source of this feature. The first thing that comes to my mind is that time was brought into the metric as a fourth dimension through ct, but if x=ct, and x is one of the 3 spatial dimensions, it follows that ct is a second measurement of (euclidean) a spatial dimension. This is ok because time can be thought of as a secondary measurement of space. We can measure time by comparing two subsequent positions of a point moving in space and let the interval of change between states stand for time. This implies that the metric automatically turns any position into a velocity, and any velocity into an acceleration. If a spacetime coordinate represents two subsequent spatial coordinates, we have the units of a velocity (even if v=0, but hardly if t=0). Likewise, a velocity would describe an acceleration. This would mean that any spacetime coordinate inherently represents motion in euclidean space, but that can only be so if the metric can describe motion mathematically, in which case we may assume that it does so via equations of motion, either implicitly or explicitly. Does this make any sense?

This is not a matter of history. Operating SR in non-inertial frames leads to the falsification of SR's postulates, especially on the constancy of the speed of light, and the contradiction is only resolved with GR. You can use non-inertial frames in SR only by neglecting Einstein's postulates and axioms. We could try the same logic on the Lorentz-invariant theory of gravitation and see if it also works (and if it is unique to GR). Anyone? My skills handling these equations are equivalent to the skills of a newborn handling a pen.

I just realised the rubber band has different effects than I intended. Please replace it for a unelastic band - a regular rope. Tks

A sphere of iron is stuck to the end of a ruber band at a point A. On the other end of the ruber band it is fixed to a point O that will act as the center of rotation. Questions: 1- If the sphere is pushed so that it achieves a speed V, with no friction and no outside forces, is it possible to achieve equilibrium, so that the length of the (stretched) ruber band and the magnitude of V both remain constant? 3- Under sufficient magnitudes and proportions, would the sphere experience shearing? Specifically, would the diameter between the point attached to the ruber band A and the opposite point B be greater than the diameter between the leading point C and the trailing point D (along the direction of revolution), and would B lag behind A in the direction of motion? Simplifying: Does AO and BO form an angle at O? Reasons why I think the sphere could experience shearing: The ruber exerts a constant centripetal force (acceleration). The circumference described by B is necessarily greater than the one described by A, hence, if AO and BO coincide (remain aligned) the speed of B would have to be greater than the speed of A. Since the ruber band = AO, it pulls the point A, which in turn pulls the point B transferring the centripetal force through the iron. This energy transfer takes time and also loses strength until it reaches the point B. I conclude the sphere would deform all around, stretching along AB, compressing along CD and also along the "poles", while the point A will experience a centripetal force directly from the ruber band. Because iron has elasticity and the transfer of momentum from A to B takes time, the centripetal force exerted on A will not be transmitted to B instantaneously, and some energy loss should be expected, so I doubt that B can be accelerated enough (due to torque from A) to keep AO and BO perfectly aligned, with the angle at O between AO and BO set to zero.