md65536

If you're willing to sacrifice the usefulness of clocks in order to try to force uniform values, I have an improvement for you. My clock is a metal sphere. The time is always t=1, from anywhere in the universe. You don't even need to observe the clock. All events and all local clocks (basketballs, marbles, etc) agree that the time will always be 1. This example confirms that time is a constant and doesn't change. I agree that an improvement in our current understanding of relativity would be helpful.

I think the examples are describing a change without time because they're describing the change between things or concepts that exist simultaneously (using some measure of change other than time) Hrm... I guess the other main property of the "measure of change" between two values is that there is a (continuous?) transformation from one value to another (and possibly vice-versa). So I'm not sure how you're describing the change between A b and c. The color of an object at a single instant can appear different to different observers, so an object appearing different colors does not necessarily require time (though... color may not make sense at all without time). But it also might not be a change because there might not be a transformation from one observed color to the other, and there may not be an ordering. Edit: Like, you could describe the ball being lit by all 3 lights simultaneously and describe the "change" in appearance across the surface of the ball, which is not a measure of time. You could say the color is changing across its surface. I don't think you would say the object is changing though. Yes, I suppose you could describe an object changing along some non-time dimension.

In the examples given (a colored ruler, or a page of math that you can "go backward or forward through") you're mapping the measurement of "change" to a 1-dimensional value, whose main property is a consistent ordering, and may or may not imply a metric or consistent measure of distance between different values. Change usually refers to a transformation from one thing to another, not the difference between two independent objects or concepts. I think it is a question of simultaneity. If two measured values can exist simultaneously (as in red and blue, or the first and second equation on a page), then the measurement of change between the two is not time. If two measured values cannot exist simultaneously, then I don't think you can describe a change from one value to another without there being a measure of time between the two. For physical objects, I don't think it's possible for an object to exist in two different states simultaneously, so I don't think an object can change without time (or at least there is a sequential ordering to its states, unless time also requires a metric in which case I don't know). But then again, it depends on what "object" means, and it may not be true for eg. particles, which might be able able to occupy multiple states simultaneously...

I also realize that I've gone from an incorrect deduction based on a misunderstanding of accepted theory, to an idea backed up only by a perceived lack of contradictory evidence, without paying enough attention to the switch in evidence. So it's now just an idea to consider, not a claim I can really back up.

In the pdf you sent me, the author describes a physical process of measuring curvature using measurements taken at two spatially separated points, and then shows that the space could be reduced arbitrarily. But then the author admits that there are practical limits to reducing the size of the apparatus due to "quantum properties" of materials. This means it is not physically possible to practically measure curvature in an arbitrarily small space due to limitations of the instruments, but wouldn't any theoretically ideal measurements themselves also have "quantum properties" that make them undefined at arbitrarily small distances? What is the point of using a definition of curvature that is well-defined at a point, and so claim that that mathematical definition corresponds to physical reality even at that point, when quantum mechanics suggests that such a definition breaks down at sufficiently small distances? We don't have an accepted theory of quantum gravity, so why would anyone talk about GR as valid "locally" even at small enough distances that it doesn't work at, where QM is needed to describe reality at such distances? Isn't that simply a case of ignoring the incompatibility of GR and QM at all scales, and pretending that one is valid anyway at all scales? Edit: I think I understand that the limit of measured curvature approaches the curvature defined at the point, as the distance between measurements approaches 0... but that this does not correspond to reality due to "quantum properties". To revise my main speculation in this thread, I would say: "There are no local effects of spacetime curvature." Except perhaps in case of singularities? Also excepting any results that might be predicted by a hypothetical quantum theory of gravity that incorporates spacetime curvature.

When traveling at any speed, a light shone in your direction of travel will travel at a speed of c relative to you. If you could travel at the speed of light, as like any other speed, light would still outpace you at a speed of c, which doesn't make sense. So are you claiming that the speed of light isn't invariant, and my first statement is incorrect? This does not agree with experimental evidence.

I thought that my questions were helpful. If you actually answer them and think about your answers you'll get started with some critical thinking that will help you figure out for yourself whether or not "it's a fact" that we are all detaching from ourselves. Here's another question: What does it say about your original post if a simple statement of agreement is treated as hostile and ridiculous? Why wouldn't you expect that what you posted not as "science fiction mumbo jumbo" but as fact, would sound right to someone? If I'm a troll then don't respond. It won't hurt you though if you try to think of answers to the questions.

You read about it in a peer-reviewed journal? And you're experiencing the effects you described? And what you wrote makes sense to you? Sounds right to me.

That's a logical non sequiter, and I don't think you need to come up with good counter points to argue against it. Though I do partially agree with some of your points. Can you say for certain whether mathematics are invented, or discovered? I think it's a little of both. The properties of many mathematical concepts are based on properties found in nature (eg. similar to systems where 1+1=2, if you put one object together with another they remain the equivalent of 2 objects rather than merging into 1 equivalent to either of the originals). The "mystery" of mathematics and the universe might be their consistency. Like with Douglas Adams' "puddle" example: If we lived in a universe where things were different, we might have a different set of maths with completely different sets of rules. If we lived in a universe without consistency, nothing might exist that could contemplate it. It should not be surprising that systems invented or discovered based on observing and contemplating the real universe, should have similar sets of properties to the real universe. The "there must be a designer" arguments seem to come from a lack of understanding and imagination. Certainly hubris plays a part, such as in "I can answer any question, and I can't think of any alternative to there being a designer, therefore that must be the case."

Oops, I was (a little) way off.

Only because you've defined it out of existence. Consider a twin paradox where two twins are separated as children and reunite later, and one seems middle-aged and the other seems very old. They compare clocks, and they agree that they have each observed a billion signals from the pulsar. They have each aged about 31 years. They agree that they are the same age. If they each had a watch with them, the older twin will have had to adjust her watch often to keep it in sync with the pulsar, as the pulsar signals often arrived less frequently (and sometimes more frequently) than the watch ticked. Likewise, all the time-related processes in the body would also run at the pace of a local clock, not caring what some remote pulsar is doing. The body ages like a crude clock... and how do you force your body to synchronize with a pulsar?

I think I know it...

pmb is saying that your method fails the following property of meaningful synchronization: "(b2) the synchronisation is symmetric, that is if clock A is synchronised with clock B then clock B is synchronised with clock A," [http://en.wikipedia....synchronisation] Edit: Well that's not quite what pmb said; I just didn't read it properly. As well, with your method, some clocks would sometimes seem slow or fast... they would not meaningfully keep time. Time would not be regular or consistent. The speed of light wouldn't be invariable. Different clocks would not be synchronized to each other, only to the one "master clock", so it would also fail "(b3) the synchronisation is transitive, that is if clock A is synchronised with clock B and clock B is synchronised with clock C then clock A is synchronised with clock C."

I'm speaking as an amateur here: Particles are not like familiar human-scale objects in at least 2 ways that are applicable here: - Particles are not always persistent. There are conservation laws such as for energy, but not particle count or type. If you smash apart one set of particles, you may find that it is now some other set of particles, and not always the same new set each time. Many particles exist only for a very short time. - The nature of existence is defined behaviorally, and the properties of particles aren't all the same as the properties of large objects. So if you consider a particle, such as a graviton or photon, you needn't always think of it "being somewhere" as a thing, only that its existence can meaningfully be considered by the measurable effects it has on stuff. The main thing about a particle is not that it must have familiar properties (size, mass, shape, location, whatever), but that it is a discrete quantity or "packet" rather than a continuous measurement. So to say that photons are particles doesn't mean that light is made of bits of material "stuff" flying around, it just means that the properties of light are essentially quantized. Gravitons would mean quantized gravity propagation. So I think you could say, rather than cracking open an atom and having gravitons spill out, you could imagine or describe the formation of a graviton occurring anywhere its properties begin to be measurable, and it comes into being not as some kind of conjuring of new matter, but simply as the measured effect of whatever process caused it. It's all properties. Particles need not have a more substantial existence than that.

No worries! It's fair to be asked to deal with time when bringing up the topic of spacetime. I didn't mean to try to own or police the thread, I just didn't want to go off topic myself, however the time-related stuff is interesting.

Well it's off topic, and I don't know for sure, but I'd say... The first question's a bit of a nonsense question, because time is a scalar value, not a vector (or object, or something else rotatable). It doesn't make sense to ask if something is rotatable when there is no rotation operator defined for it. The answer to the second question is that a rotatable vector with a time component can be rotated. For example, the 4-vector representing the length and orientation of a ruler can be rotated onto the time dimension. Then it represents the time it takes light to cover the length of the ruler, or perhaps the ruler traveling at the speed of light. Just because you can do this rotation mathematically doesn't mean there is any physically possible equivalent. A material ruler is not the same as a 4-vector representing its length and orientation, and a 4-vector of (t,0,0,0) is not the same as a physical clock.

Thanks for all the information. I'll try to revise the speculation. Sorry if I go off the rails again... The proposition of this thread is wrong. Gravitational acceleration is not a local effect (a test mass accelerating in free-fall feels no proper acceleration) so a test mass need not measure a gravitational force in order to be affected by it. Gravitational acceleration is therefore a relative effect, such as can be observed as a difference in acceleration between two spatially separate masses. (So there we have the main idea, that gravitational acceleration may be meaningless without multiple points of observation.) Further speculation: All gravitation does require non-zero spacetime curvature, just not locally. A uniform gravitational field that is not bounded by some space with curvature is the same as having the entire universe experiencing a constant acceleration in free-fall, which is meaningless without something to accelerate relative to, and can't be measured (no proper acceleration). Does that mean that gravity wouldn't need to be a field effect??? Locally, gravity is just inertial movement. Only the spacetime curvature is a field. Only a gravitational gradient could be measured locally.

Yes please! I obviously don't know the answer to the title of the article, and I can't imagine how tidal forces could be measured locally. Thanks... I've only begun to look at your article, and I doubt I'll understand it all, but I guess I've had it all wrong. I thought spacetime curvature corresponded to the magnitude of gravitational force, but it only corresponds to the change in gravitational force?, or as you quoted Einstein: "The equivalent GR name for such tidal gradients is spacetime curvature." So a uniform gravitational field would have no spacetime curvature? The paths of objects in freefall in such a field would be curved, but spacetime itself would be flat? And would geodesics or the path of a light signal would be straight according to any relatively stationary observer in the uniform field? I'll try to explain what I meant, with the realization that it is a flawed argument and I'm using the notion of spacetime curvature incorrectly. Yes, I mean a point particle with mass, and a size of zero (not negligible size or infinitesimal, but actually zero). I am speaking of the test particle observing or measuring local spacetime. I'm basing my argument on the idea that if an object behaves a certain way due to a given environment, then the properties of the environment that cause the behavior must be measurable or observable by the object. If it is impossible to measure a property, then it is impossible to be "properly" affected by that property and behave expectedly. However as I realized, this is not the case in my argument because the behavior of the test particle is relative, or different according to different observers. The "proper" behavior of a test mass is to behave as if it is in free fall. It would not have to (or even be able to) know if it was in freefall in the absence of gravity or in the presence of a uniform gravitational field (with an absence of tidal effects in either case). It would not need to be able to measure a gravitational field in order to behave expectedly. Or the other way to see it, which might be related, is that the test particle may "know" its tangent space, and know how it can move, and if it moves it will follow the curvature of spacetime without ever needing to know what that curvature is.

That might be an important part of the answer but if so I'm not seeing it. What I'm trying to describe is the notion that "local spacetime is flat". So a point observer should not be able to measure any curvature using only local measurements. If the spacetime curvature is defined and non-zero at that point, it can only be measured by other observers???, or by incorporating information from other observers. What I don't get: Does spacetime have an intrinsic curvature (as in a Gaussian curvature) that is independent of how or from where it is measured? If so then what is the meaning of "local spacetime is flat"? Are both measures speaking of the same property, the same meaning of "curvature of spacetime"? So as an example, if you have a function like "y=x", with a slope of 1, that slope can be measured at any x using only local measurements. If you sample the function at y1=x1, and at y2=x1+epsilon, you can determine the slope no matter how small epsilon is (as long as it's non-zero, so maybe my point is lost anyway because you couldn't measure the slope at a point even if the function isn't "flat" locally). The limit of the slope as epsilon approaches 0, is 1. If local spacetime is flat, then the only curvature that should be measurable in the space around a point P + epsilon, should be 0 as epsilon approaches 0. The only local curvature that should be measurable is "completely flat". I'm not sure now where my reasoning goes wrong.

So the Gaussian curvature is defined for a point, and wouldn't matter how small R was chosen? The limit of the Gaussian curvature would be a non-zero number, as R approaches 0? Still, your example and the ones on wikipedia (ants on a surface drawing a triangle and measuring the angles) requires making measurements from more than one location, which is exactly my point in this thread. Is there any way to measure the Gaussian curvature at a point on a surface without using measurements from more than one location? (Nor using some measure over a spatial extent other than a single point.)

I looked it up and came across: http://en.wikipedia....i/Tangent_space They use an example of a tangent space of a point on a sphere, which is a plane. I think what you're saying is that even though the tangent space is "flat" in this example as it is for a point in spacetime, the curvature of the manifold (the sphere or spacetime) is defined even at that point. By analogy, my argument would be that such a point wouldn't be able to tell it was on a sphere. At a small enough scale, the area around the point becomes indistinguishable from a plane. But I don't think that matters, because though the tangent space is flat, if the point is moved in any direction on that tangent space, the point moves on the sphere and not on the tangent space. So if there was a point mass, it would follow the curvature of spacetime without having to measure the curvature at that point. It's kinda over my head so I don't know if what I wrote makes sense. If so, does this imply that a point mass wouldn't "know" which direction to accelerate toward, but any movement at all (even random) would cause it to behave properly (ie. accelerate toward gravitational masses)? If location is subject to Heisenburg uncertainty but curvature isn't, then perhaps a (point) mass could not be defined in a way that it can "remain at rest in a fixed location, experiencing local flat spacetime" and thus avoid gravity, so it wouldn't require any specific movement at all in order to behave as a mass does. --- Sorry if I'm quickly jumping into nonsense.

That would involve receiving information from a separate location, rather than detecting a gravitational field locally. There is no curvature at the observer's (point) location, at least according to the observer. Perhaps I'm confusing curvature and gravitational field. I know that a gravitational field means curved spacetime, but does detecting one mean you can detect the other? Also, a mass in free-fall wouldn't even need to know that it is being pulled toward something; it wouldn't need to know if the spacetime it's moving through is curved or not. So my idea's probably flawed.

If you could separate the axes, I suppose similar reasoning might imply that there is no way to measure time with a single spatial location, so no passage of time. I think I've argued this before and would try again, but others have pointed out that there is no known relation to spatial extent in some time-related processes like decay of particles. So I would say that a point particle without spatial extent has no mass and does not age. Then, if something has mass and by my reasoning has spatial extent, then that spatial extent also extends in time, because it makes no sense to speak of multiple locations in a single universal instant. (Unless somehow the locations were time dependent so every observer who sees the mass in a single universal instant would necessarily see the locations as different, compared to what other observers see. I don't see how that could make sense.) I think that curvature can only be expressed using multiple axes? And there's nothing that suggests more than one time axis? So any "curvature of time" would only make sense as a curvature of spacetime. I think this is related to the fact that a local clock always ticks at the same rate. If you could measure a local clock deviation I think you'd be able to measure a local spacetime curvature. Similarly if you could measure a local spacetime curvature, you'd be able to specify an absolute direction of motion maybe??? Or at least acceleration. It almost seems like having a local spacetime curvature is like the idea of something moving away from itself/its own location. So does this also mean that proper acceleration cannot be defined for a single point???

Given that local spacetime is flat, there should be no possible way to measure any curvature at a single point. With no curvature, there is no gravitation. If a mass can be a point mass, it would need observations or measurements of spacetime from multiple locations in order to determine any curvature and be affected by it (eg. gravitational attraction). The minimal spatial extent of a mass must include multiple spatial points of observation (as in a particle with size, or multiple point particles somehow combined and sharing information, or a single point particle making observations from different locations). Is this a sound argument?