Why Doesn't Relativity Apply to Light?

[JesseM]

How does one add a quote into the respone? I see the checkbox here in the QUICK REPLY window, but it does not allow me to check it. When I go GO ADVANCED, I see nothing regarding unfortunately QUOTE.

Just press the little "quote" button at the bottom right of the post you want to quote from. Then if you want to break up the comment into multiple quotes, use the {QUOTE}...(quoted text goes here)...{/QUOTE} tags for each chunk of text, but with square brackets instead of the curly brackets I used there. There's a guide to all the tags you can use https://www.physicsforums.com/misc.php?do=bbcode .

 

[jtbell]

Note that if you position your mouse over the "quote" button without clicking the mouse, a little text-box pops up with the words "Reply with Quote". At least my browser (Firefox) does this. If you see any other buttons or widgets whose purpose you don't know, this might help.

 

[gonegahgah]

Hi Doc

My entire life is spent just to get on your goat. Sorry about that.

Hi Jesse

But in the Earth's frame, your rulers keep shrinking and the clocks keep slowing down each time you accelerate to a new velocity, and each time you resynchronize your clocks after attaining a new velocity they get progressively more out-of-sync...so why should an Earth-observer be surprised to find that your increase in speed relative to the Earth grows smaller and smaller with each jump, even though by your own measurements each jump increases your speed by 0.1c relative to your previous speed?

Yours is a good explanation too which is afterall what we are looking to do for Line the original poster. My disagreement with the idea is incidental. The surprise for today's scientist's would be if it didn't happen the way they expect. So if instead the rocket suddenly disappeared - instead of the rocket's rate of acceleration slowing down as it approached light speed relative to us on Earth - there would be a lot of head scratching going on.

I think we can all agree that if you have a ruler on any ship or vehicle and no matter what its speed then if you mark off a centimetre while you are traveling away from the Earth with the pencil moving away from the Earth that that centimetre will actually transcribe more than an actual centimetre in Earth's frame. Of course, because the spaceship is moving while you are drawing the line; so the pencil travels more distance than one centimetre away from the Earth while it appears on your spaceship that it is traveling only one centimetre. This is true but linear ie the faster the spaceship is is proportional to the distance covered by the pencil relative to Earth. SR is not linear though and the rate - as you say - decreases exponentially as the speed of light is approached.

To bring things back to the Newtonian example, suppose the phony gag rulers were built to actually shrink or expand depending on their speed relative to the observer with the normal rulers and clocks, and suppose the phony gag clocks were built to slow down or speed up depending on their speed relative to him. Also suppose that each time the observer with the gag rulers and clocks changes velocities, he resynchronizes his clocks using the assumption that light travels at the same speed in all directions in his current rest frame (which, again, would actually be a false assumption in this Newtonian world--light would actually only travel at the same speed in all directions in the frame of the observer with the normal rulers and clocks, who we can assume is in the rest frame of the ether). Now, do you agree that in this purely Newtonian situation, we'd get exactly the same results as in the relativistic situation with unmodified rulers and clocks?

I'll have to wrap my head around this a bit more. I'll get back to you on this later.

In the meantime I just want to add some more interesting aspects of SR.

Let's again say we have three observers: observer A stays on Earth, observer B shoots off in one direction from Earth at half light speed, observer C shoots off in the other direction from Earth at half light speed.

B and C watch their clocks and wait for 1 hour to pass and report this to observer A. A gets their reports at exactly the same time.

At the same B and C report to each other but B gets C's report later (much later) than the hour and the same vice versa. So even though A gets their reports at the same time B & C get each other's reports at different times. (Assuming an instanteous means of communication).

Also here is another interesting thing about SR.

If a spaceship speeds away from Earth at 0.9c then the people on the spaceship will appear to slow down to us on the Earth. They will age slower.

The interesting thing though is that to the people on the spaceship the Earth will actually be receeding at 0.9c so that in this relative world and according to the rules of equivalence of SR then to the people on the spaceship it will appear as if the people on the Earth are slowing down. So the people on the Earth will appear to age slower to the people on the rocket.

So both will see the other aging more slowly and see themselves aging normally. When they get back together who will actually have aged more?

 

[AnssiH]

So both will see the other aging more slowly and see themselves aging normally. When they get back together who will actually have aged more?

Whichever is the one who actually "turned around", i.e. actually accelerated towards the other one (who continued in inertial frame). If both start accelerating towards each others and meet "halfway", then the aging is symmetrical... Surely you knew this, just had to test? :)

Anyway, I think people should talk more about how things look like in SR when we imagine an instantaneous communication (like you do), because it underlines the real point and at the same time the ontological weirdness of SR. Too many people think Einstein merely talks about information delay... :I

 

[pervect]

The problem is that the defintion of "instantaneous communication" depends on the frame of the observer. One persons instantaneous coummunication is seen as communication with the past, or the future, by a different observer. Therfore I don't think it is a good idea to talk about relativity and "instantaneous communication" - the concept is frame dependent, and causes much more confusion than illumination.

 

[AnssiH]

I think it is a good idea just for the reasons you mention. It gives people a clearer picture of reality as described by SR. If people understood better what sort of reality SR describes, there would be much better dialogue about the ontology of SR and especially the ontology of time.

EDIT: Let's still specify that when I say "imagine an instantaneous communication", I do not mean to imagine what would happen if people could communicate instantaneously in this or that inertial frame, but to imagine what the world "really" is like around them at a single instant and what happens to this "instant" when they change direction. This just because it seems so difficult to really drive it home that relativity of simultaneity is not about the order in which different events are observed in different locations in space, which is the way even many documentaries have interpreted Einstein's thought experiments about the train and embankment... 95% of the dialogue around relativity is still about twin paradox or some variation of it, and the problem is always that relativity of simultaneity has not been properly grasped, or even introduced... :I

 

[pervect]

Keep me on the "totally disagree" list, please.

ps - if your'e interested primarly in philsophy, you might want to check out http://philsci-archive.pitt.edu/archive/00000638/00/kant,_goedel_and_relativity.PDF

which should at least serve as an exxample that it's quite possible to philosophize about time at quite great length without introducing the results of impossible experiments.

 

[JesseM]

EDIT: Let's still specify that when I say "imagine an instantaneous communication", I do not mean to imagine what would happen if people could communicate instantaneously in this or that inertial frame, but to imagine what the world "really" is like around them at a single instant and what happens to this "instant" when they change direction.

As an ontological view, I think it makes little or no sense to say that the set of simultaneous events in an observer's instantaneous inertial rest frame represents what the world is "really" like around them. (How can you use the word 'really' if it's observer-dependent? And even if you allow reality to be observer-dependent in this way, why privilege inertial reference frames when they can only be defined locally in general relativity anyway, and GR says that the laws of physics will work the same way in any coordinate system?) The only views I've ever heard either philosophers or physicists advocating are

1) block time--the fundamental reality is 4D spacetime and the worldlines in it, all talk of simultaneity is specific to different coordinate systems placed on this spacetime, with no more ontological significance than the orientation of your spatial coordinate axes (most physicists who adopt any sort of philosophical view about relativity tend to adopt this one, I think)

2) time "really passes" relative to each observer, in the sense that each observer can say that anything in their past light cone is set and anything outside it (future light cone or 'elsewhere') is not (the physicist George F. R. Ellis seems to advocate a view like this http://spacetimecenter.info/4DBook/SpaceTime-Ellis.pdf )

3) time "really passes" in the sense that there is some "metaphysically preferred reference frame" that represents the true present, even though no empirical experiment will distinguish this frame as physically preferred in any way

 

[pervect]

It's also possible to say that the notion of simultaneity is, in Kant's terminology, "transcendental" - basically, the product of human consciousness.

Note that there have been some interesting experiments done in how the brain synthesizes the order in which events occurs from nerve signals that arrive with different propagation delays. The human perception of simultaneous events can be "tricked".

I *think* that this is the position (that simultaneity is transcendental) is the paper I quoted earlier takes, I must admit I haven't read it all that carefully.

This position (roughly speaking, that "Now" is an illusion) may be a bit too extreme, though. Certainly simultaneity has some practical use in defining momentum in an inertial frame. It's also clear that simultaneity depends on the frame of reference in this context.

I'm sure that there has been a lot written about the philospohy of time in relativity, and I offer the paper I cited and its reference list as an example. I don't personally have all that deep an interest in philosphy, though. I would expect that the best place to find people interested in philosophy would be the philosophy forum - I don't know for sure how many people there are interested in the philosophy of relativity though.

 

[MeJennifer]

It's also possible to say that the notion of simultaneity is, in Kant's terminology, "transcendental" - basically, the product of human consciousness.

Not only that but many seem to have a desire to "explain" everything in the universe in terms of some sort of plane of simultaneity, by back calculating the relativistic and Doppler effects instead of taking these things at face value. Apparently in the belief that that approach matches reality better.

 

[AnssiH]

As an ontological view, I think it makes little or no sense to say that the set of simultaneous events in an observer's instantaneous inertial rest frame represents what the world is "really" like around them. (How can you use the word 'really' if it's observer-dependent? And even if you allow reality to be observer-dependent in this way, why privilege inertial reference frames when they can only be defined locally in general relativity anyway, and GR says that the laws of physics will work the same way in any coordinate system?)

Well the "really" was in quotes for this reason. "Really" in the sense that in SR relativity of simultaneity is not an "optical illusion" but real effect. What the "now"-moment is "really" like in their subjective experience (but beyond their natural senses)... I could probably articulate myself more clearly but I think it is not necessary here. The point was just that too many people miss this and start yet another thread about twin paradox, when it is much more important to talk about the points you raise.

The only views I've ever heard either philosophers or physicists advocating are

This is the kind of dialogue that I'm advocating. It is pretty important because the different views have further implications and/or complications to different areas of ontology, some more obvious than the others... To just mention some from the top of my mind;

1) block time--the fundamental reality is 4D spacetime and the worldlines in it, all talk of simultaneity is specific to different coordinate systems placed on this spacetime, with no more ontological significance than the orientation of your spatial coordinate axes (most physicists who adopt any sort of philosophical view about relativity tend to adopt this one, I think)

- This offers a way to interpret QM-phenomena in deterministic sense (that "light beam" exist in static sense in spacetime and its spacetime shape is such by its real fundamental nature that the "future" measurement is evident already at the moment of emission)

- It ignores the requirements of conscious experience (conscious experience must be caused by something that exists in reality, and it is pretty hard to reason that absolutely nothing changes in reality when there nevertheless exists change in conscious experience. Note that this is different from the conscious sense of "speed" of time, but more of that below)

- Oftentimes people include the assertion that "consciousness" moves through spacetime, without any consideration about how motion and static spacetime are pretty much mutually exclusive semantical concepts; more words are needed. Lots more.

2) time "really passes" relative to each observer, in the sense that each observer can say that anything in their past light cone is set and anything outside it (future light cone or 'elsewhere') is not

I didn't read the article you linked to yet, but from the top of my mind;

- It could have the power to explain why there is a subjective experience of motion, but it also introduces very uncomfortable idea of motion "besides" spacetime; if you assume that spacetime causes the motion (that we have a semantical idea of), then it is pretty odd to assume that spacetime itself, or some other entity besides spacetime block, was in motion itself. I.e. any sort of change or motion to reality is hard to reason if it is first claimed that motion is kind of a semantical illusion and does not exist. So it strongly seems like only "motion" or "time dimension" can be of fundamental existence, but not both.

- Even though our subjective experience is occurring at certain speed, obviously the speed we "experience" depends on the rate our pattern recognition system works in relation to the systems we are recognizing. And this ratio is completely defined in spacetime diagram already. So since we describe the brain and the other system in spacetime diagram already, the "speed of time" makes no difference to the experience and cannot be measured; it is a non-sensical concept. Even the direction of time doesn't necessarily change the experience since we have already defined the relationships of things in spacetime and these won't change. (I.e. while we can see that some sort of metaphysical "pointer" could define the "now" for each observer, it is non-sensical to assume its speed defines anything at all)

- This tends to lead into naive ideas of "self"-entity with identity. A duality of a sort.

3) time "really passes" in the sense that there is some "metaphysically preferred reference frame" that represents the true present, even though no empirical experiment will distinguish this frame as physically preferred in any way

- A preferred frame is obviously bad concept because it makes the description of nature so complex, and furthermore, it hardly makes sense ontologically. To assume that space has identity and is another "entity" from matter but still transmits "waves" like we observe matter to do is similar to assuming that "atoms" are made of matter which is made of atoms, or that our brain is conscious because there is a little man somewhere in there (homunculus argument), or, indeed, that motion is caused by time dimension and conscious experience by motion in time dimension. So, assuming space is an empty backdrop is pretty naive.

But it must be said that "preferred frame" is different idea from "absolute simultaneity". The former refers to the idea that light moves at specific speed in one "frame" (and would lead to absolute simultaneity), but absolute simultaneity does not require preferred frame. Ontology must go deeper than this. Even "spacetime" sets absolutes that may not be true at all.

Obviously all the observable phenomena of relativity can be explained by many sorts of models where simultaneity is absolute (which it needs to be if motion is considered fundamental), just not by the means of spacetime and the geometrical elegance this provides. "Elegance" is hard to measure because it depends on the context, many chaotic systems can be approximated with very simple math, while it may be impossible to accurately describe their true nature, which is a complex interaction of few simple functions.

But it is very hard to find any different models with elegance when my mind is occupied with spacetime view of reality, because the required paradigm shift is so very hefty. But I don't feel the need to commit to any particular view of time, but I may be leaning a bit towards fundamental motion. With that, I wish to describe a fourth possibility; That motion really exists fundamentally and there is only one notion of simultaneity that exists.

Obviously before this could make any sense, it requires a paragidm shift from spacetime to such reality where light doesn't exist in any sort of "empty spacetime" but actually moves in the environment that is caused by matter itself. We can consider atoms as systems that are the size of their whole influence, not just what we call the nucleus. So there is no such thing as "empty space", and light can only have any "speed" because it is information that travels inside matter (in its extended sense). In this view it is not clear where one object ends and another begins, and the idea about "objects in space" would just refer to the model we have built when we have observed how light behaves with the stable systems that are the centers of the atoms.

This could say something about the routes the information takes in QM experiments, and it also could say something about the routes light takes near large masses (gravity) and perhaps what gravity is (since "light" is what keeps objects together; whatever routes it takes between individual atoms will cause motion to objects). All in all, its a view where "light & matter" duality or "matter & space" duality does not exist at all, but matter is merely some sort of stable interaction loop, and the functions of an atom that are currently considered fundamental (like inertia) are just emergent functions of the system.

I don't know if its workable but it is about the only reasonable idea I can think of currently, if I first assume that "motion" exists instead of "time dimension" -> simultaneity is absolute.

 

[AnssiH]

I'm sure that there has been a lot written about the philospohy of time in relativity, and I offer the paper I cited and its reference list as an example. I don't personally have all that deep an interest in philosphy, though. I would expect that the best place to find people interested in philosophy would be the philosophy forum - I don't know for sure how many people there are interested in the philosophy of relativity though.

Yeah, it seems that most philosophers don't really care about relativity enough to even know what it really says... That is also the reason I call for better and clearer representation of the idea of relativity of simultaneity to the mainstream. If the philosopher community really grasped this idea, I'm sure it would spark some interesting thoughts on the issue. Maybe even clarify which position seems like most coherent to pick, if one abides to materialism.

Thanks for the link to the article, didn't have time to check it out yet though...

 

[JesseM]

Well the "really" was in quotes for this reason. "Really" in the sense that in SR relativity of simultaneity is not an "optical illusion" but real effect.

It isn't an "effect" at all, it's based on a particular choice of how you synchronize your clocks. If you have a ship that accelerates in such a way that its length remains constant in its instantaneous inertial rest frame at all moments during the acceleration (the condition of 'rigid' acceleration), then clocks at the front and back of the ship will not naturally stay synchronized in the ship's instantaneous rest frame if they were synchronized in its rest frame before it started the acceleration. If the ship then stops accelerating and is at rest in a new inertial frame, observers on the ship would have to manually reset the clocks at the front and back so they'd be synchronized according to this new rest frame's definition of "simultaneity", assuming each inertial frame uses Einstein's clock synchronization convention to define simultaneity.

Of course, there is a very good physical reason for observers at rest in a given inertial frame to synchronize their clocks using this convention, namely that if all inertial observers synchronize their clocks this way, they will each find that the laws of physics work exactly the same way in their own frame as they do in every other inertial observer's frame, including the fact that they will each measure light to move at c. This wouldn't be true if they adopted a different synchronization convention. Still, it is just a convention, it's not like time dilation or length contraction where if I accelerate to a new velocity my clocks and rulers will naturally measure length and time the same as clocks and rulers which have always been at rest in that frame.

1) block time--the fundamental reality is 4D spacetime and the worldlines in it, all talk of simultaneity is specific to different coordinate systems placed on this spacetime, with no more ontological significance than the orientation of your spatial coordinate axes (most physicists who adopt any sort of philosophical view about relativity tend to adopt this one, I think)

- This offers a way to interpret QM-phenomena in deterministic sense (that "light beam" exist in static sense in spacetime and its spacetime shape is such by its real fundamental nature that the "future" measurement is evident already at the moment of emission)

This sounds a bit like the transactional interpretation of quantum mechanics, but block time doesn't force any particular interpretation on us, block time is equally compatible with the many-worlds interpretation or bohmian mechanics.

- It ignores the requirements of conscious experience (conscious experience must be caused by something that exists in reality, and it is pretty hard to reason that absolutely nothing changes in reality when there nevertheless exists change in conscious experience. Note that this is different from the conscious sense of "speed" of time, but more of that below)

Unless you believe in a supernatural soul, the contents of consciousness are a product of information-processing in the physical brain, and you should be able to explain people's sense of change in terms of this information-processing. Block time won't change your predictions about what sort of output a computation will produce, and this includes the output of the brain.

2) time "really passes" relative to each observer, in the sense that each observer can say that anything in their past light cone is set and anything outside it (future light cone or 'elsewhere') is not

- It could have the power to explain why there is a subjective experience of motion,

Again, only if you reject the view that all our behaviors (including reports of subjective experiences) can be explained in terms of what's going on in the physical brain. If you accept this, then the output of the brain is not going to be affected by which philosophical view of time you like, since they don't make different predictions about the measurable behavior of actual physical systems.

But it must be said that "preferred frame" is different idea from "absolute simultaneity". The former refers to the idea that light moves at specific speed in one "frame" (and would lead to absolute simultaneity), but absolute simultaneity does not require preferred frame.

Doesn't it? If there is absolute simultaneity, there is only one inertial frame in the relativistic sense whose definition of simultaneity will match that of "true" simultaneity, so it will be preferred in some sense (even if in a metaphysical sense rather than a physical and experimentally detectable sense).

Obviously all the observable phenomena of relativity can be explained by many sorts of models where simultaneity is absolute (which it needs to be if motion is considered fundamental)

But these models would necessarily say that only one of the inertial frames of relativity would have a definition of simultaneity which matches absolute simultaneity. And unless these models actually made distinct predictions about the results of experiments, then this preferred frame would be absolutely indistinguishable from any other frame on an empirical level.

Anyway, to get back to the main point: whatever relativity says about simultaneity, almost no one would say that it tells you that what's "really" going on around an accelerating observer at any moment is defined in terms of which events are simultaneous in his instantaneous inertial rest frame. That wouldn't be true in any of the three views on time I mention above, and to me it seems fairly incoherent.

 

[AnssiH]

ps - if your'e interested primarly in philsophy, you might want to check out http://philsci-archive.pitt.edu/archive/00000638/00/kant,_goedel_and_relativity.PDF

time, together with space, is one of the main criteria for the reality of a concrete object or event, physical or mental as it may be.

I wish to voice, yet again, a strong objection against this. Time is not a "criteria for reality of an object or event". It could be this way, but we cannot claim it definitely is.

To say that events could not exist without time or to say objects could not exist without space is very naive realism. It comes from naively imagining a world according to you worldview where there exists space and in it objects, and noticing that it is impossible to remove "space" from that view.

But space and objects are concepts that you have come to form so to build an artificial mind-model of reality around you, and the brain does this so to be able to predict how some systems unfold. Space cannot be removed from the worldview only insofar that your worldview is such that you interpret reality in terms of object & space duality.

Note that to say "space" is not real is not to say that our mind creates the world in some idealistic sense, it is just to say that space is not a metaphysical entity, that it is not a huge backdrop with identity to itself. It is to say that there simply is what we call "distance" between what we call "objects", and we naturally attach identity to this so-called "space". But we understand space cannot be measured or detected, that it makes no sense to posit that we are really moving "through space" even when we make a trip to Mars (imagine the difficulty to explaining why we don't move through space to anyone who had not yet adopted the idea of Newtonian relativity).

When we refer to speed, we do not refer to speed in relation to space, but the speed between two objects; Only distance between objects can be measured, so we can "kind of" understand that space is not some sort of metaphysical entity. Space as a real "entity" is a figment of imagination, not a requirement for objects to exist. Same thing with time!

To say that time must exist for any event to exist is to naively imagine a world according to your worldview where time exists and noticing that it is impossible to remove "time" from that view. Again, what we observe is motion, and when we refer to time, we are only relating the motion of two objects with each others. Like we cannot measure "space", we cannot measure "time", although some people tend to think that way when they think about how a single clock can "measure time". It does not measure time, it just moves, and the reason this motion has any meaning to the semantical idea of time is that it relates this or that way to the motion of some other system.

So it is erroneous to bluntly assume what the writer assumes, and this error is evident in further writing:

The second, related reason, is given by the fact that space and time yield a principle of individuation. While space distinguishes and separates physical objects and events that co-exist or exist at the same time, time is used to distinguish states or events belonging to the same substance, remaining in the same place or moving across space

I hope it is clear at this point to all that space separates "physical objects" only if one happens to interpret the world according to worldview where there exists such concepts as "space" and "objects".

Here it must also be pointed out that the error of assuming metaphysical identity to space and time is just an instance of a larger error of attaching metaphysical identity to anything, or to assume there really are "objects" in objective sense. And why this is erroneous becomes clear with some understanding about how and why we understand reality. Clearly this has not been understood by the writer, as the error keeps arising:

If time (together with space) were a non-entity (unreal), how could it yield the most important criterion of the reality of things and events? Shouldn’t this criterion imply, by itself, that time is, in some sense, real?

How can we explain the fact that objects and events are objectively
“separated” by space and time without also assuming that the latter, in some sense exist, either as “carrier” of the spatiotemporal relations in empty space, or as real, mind-independent relations exemplified by physical entities?

Here the mistake manifestates itself in so many ways that I feel it would be impossible to connect with the writer with just few words... I think I should just suggest a larger paradigm shift instead of point out to individual errors.

Consider the reality of a tornado. It never consists of the same "stuff" for very long, but what we refer to as a "tornado" is the stable pattern of circular motion. There is no real identity to tornado as if it was a metaphysical "entity". What the tornado is, at most, is a stable pattern, and I suggest you to view absolutely everything as stable pattern instead of something with metaphysical identity. Consider the chair you are sitting on to be just like the tornado in that it is just a stable pattern, or stable functions, which cause the reality which brain classifies as "a chair".

I cannot convince you exhaustively that reality really is such a place where there is no actual identity to anything, but I can assure you that if you assume this to be true, you will reap the rewards when considering the philosophy of the mind or any physical phenomena. In the philosophy of the mind it is important to get away from metaphysical identity of "self", including the idea that our identity is the matter we consist of.

Now, the reason we are so inclined to assume identity to things is that it is the the way that the brain forms the mental model of reality. Before reading the paper, I did not know there existed such a concept as "noumenon", but reading the wikipedia page it appears to me that the concept has not been fully understood.

It is immediately wrong to imagine any "event" as a noumenon, because just the concept of events is a semantical concept with no metaphysical merit. Whatever change we care to tag with a name can be called an event, just like whatever stable pattern we care to tag with a noun can be called an object, but it does not mean these things have metaphysical merit, they are just tools for predicting future "stable patterns".

So what the concept of noumena says is that the reality we can comprehend is the artificial model that is the result of brain having classified different stable patterns into semantical "objects" and "events" and such things, while the raw form of reality is not "like" this at all, it is not a backdrop of empty space with identity to its locations, in which objects with identity float around. This is just the way we understand the reality of the stable patterns. Like I've said before, if you imagine reality as if its a continuous "fluid" in which every different "thing" is just a different "shape" but made of the same "stuff", you are closer to reality (although at the same time you must understand in which ways this too is wrong)

And with this it should become clear that any idea about time as a dimension with identity to itself, or as a prerequisite of motion, is entirely dependent on the particular worldview of the individual, not a requirement for a reality to exist.

I think with all this in mind, it would be interesting if people tried to interpret the observable phenomena that relativity predicts in terms of real evolution of the stable patterns instead of in terms of geometry in spacetime.

time is empirically real but transcendentally ideal

Time is empirically real only if one interprets the experiments in terms of time and space instead of motion and stable patterns.

 

[AnssiH]

It isn't an "effect" at all, it's based on a particular choice of how you synchronize your clocks.

I understand there are many ways to look at it, and the point of what I said was not what words to use, but rather to underline the real difference between absolute simultaneity and relative simultaneity.

I don't know what your background is, but I suspect this difference has been so obvious to you for so long that it is hard to see why anyone would miss the point when it is laid out in front of their eyes. But my experience is that they do miss the point, because they assume that the concept refers to the order in which an observer measures the events through his natural senses due to the limited speed of light, not due to the isotropic speed of light. It is clear that this mistake has been made even by people who make educational TV-programs about the issue. And that is not acceptable.

Of course, there is a very good physical reason for observers at rest in a given inertial frame to synchronize their clocks using this convention, namely that if all inertial observers synchronize their clocks this way, they will each find that the laws of physics work exactly the same way in their own frame as they do in every other inertial observer's frame, including the fact that they will each measure light to move at c.

Yeah its true its just a convention, but I also think it is very reasonable to assume that the laws of physics are the same in each frame, due to what I said about space and its identity.

At the same time it must be noted that the "environment" where light moves, if it is not a spacetime construction (which is an absolute construction in itself), is also governed by laws of physics and thus it is found to behave the same way regardless of your direction of motion to any other observer. (But "frame" is not a good concept at this point).

It must be remembered, that even if light moves in spacetime in such way that its speed is isotropic, its properties are not symmetrical to each frame (like its frequency). The reason this is important is to remember that the properties of light are not a requirement for physical laws to be the same, and even if the observers did measure different speed to the light, it would not mean the physical laws would be different, for the speed of light is just a parameter of light, just like its frequency. Different parameters yield different results with same laws.

Unless you believe in a supernatural soul, the contents of consciousness are a product of information-processing in the physical brain, and you should be able to explain people's sense of change in terms of this information-processing.

You cannot describe information processing without change. It is obvious that the state of the brain or the contents of subjective experience at any given moment can be described in spacetime diagram, but just the static existent of the spacetime diagram cannot be used to explain conscious experience where motion does exist. I know this is little bit tricky to realize though.

Let me put it this way; what you say above about how information processing is our comprehension of reality is true, but more words are needed to get to conscious experience of flow of time. Just that there exists patterns in spacetime (in brain) that express such idea as time and flow of time and so on, is not enough to understand why the experience exists the way we experience it. Otherwise it would basically suffice to draw a spacetime diagram of the brain and say the diagram now believes there exists flow of time, just by sitting on the paper. This is about comprehension of this idea of block time, not so much about whether it can be true or not.

Anyway, to get back to the main point: whatever relativity says about simultaneity, almost no one would say that it tells you that what's "really" going on around an accelerating observer at any moment is defined in terms of which events are simultaneous in his instantaneous inertial rest frame. That wouldn't be true in any of the three views on time I mention above, and to me it seems fairly incoherent.

I know I struggle with the correct words to use, but like I said, I think I could articulate myself more properly if I spent more time to it and if it was important to this discussion. But it is not as I hope I clarified in the first paragraph of this post.

Let it be said that I do think I am saying too much when I posit any idea of "true" now-moment per observer, but I think it is a valid first step in breaking free from Newtonian simultaneity, like copenhagen could be the first step towards quantum mechanics, even though it too says things that cannot be justified, and need to be refuted later.

 

[Aether]

...the point of what I said was...to underline the real difference between absolute simultaneity and relative simultaneity...its true its just a convention, but I also think it is very reasonable to assume that the laws of physics are the same in each frame...

The laws of physics can be written with tensor notation. Because of this, we can choose to do physics in http://bautforum.com/showpost.php?p=724212&postcount=124" coordinate system as long as we do all the transformations correctly. By adopting the two postulates of SR we can choose to do physics in a set of coordinate systems where the tensor notation collapses down into a simpler notation, but this is just a convention, and there isn't anything intrinsically "real" about this choice.

 

[AnssiH]

I don't know how it got so long again but...

The laws of physics can be written with tensor notation. Because of this, we can choose to do physics in http://bautforum.com/showpost.php?p=724212&postcount=124" coordinate system as long as we do all the transformations correctly. By adopting the two postulates of SR we can choose to do physics in a set of coordinate systems where the tensor notation collapses down into a simpler notation, but this is just a convention, and there isn't anything intrinsically "real" about this choice.

Yeah, so, have I interpreted this correctly when I say that one could assume, for example, that there exists an ether if it is also assumed that the laws of physics transform accordingly to each frame (which in essence hides the ether from view?)

In which case which ever ontology you choose from these two is going to be an arbitrary choice, or down to some slightly more ambiguous criteria like "elegance"?

I still stand by with my assertion that it is reasonable to assume that the laws of physics really are the same in each frame, even though this is just an assumption and cannot actually be proven to be the "right way" to understand the system (After all, there are many arbitrary choices we have made in our worldview just to get this far :).

But it must be noted that I don't justify this, like most people tend to, with the geometrical simplicity of relativity or because with C against fixed ether you'd need to dream up ways to hide it, but because of, let's say "ontological elegance". After some thought about how we understand systems including reality, ether looks a lot like "naive realism". But so does spacetime.

Here I think I must go little bit into semantical details to really make sense. When I say "laws of physics really are the same in each frame", frame does not mean direction against any "fundamental" backdrop in any sense, it just means that an object which is not feeling acceleration is going to act the same way regardless of its direction in space relative to any other object.

Such a frame is entirely defined by whatever environment we imagine the light to move in (for example, inside extended atoms), and whichever way we imagine that environment itself to be "bent" makes no difference to this particular definition of a frame. Any object moving in a bent frame will move straight but still end up just where it left (like in GR).

This is simply an attempt to remove any unnecessary idea of "fixed" space or even spacetime from the mind. Here I am assuming that light and matter as semantical objects really are the bastard children of each others; they manifestate each others, "mass" and "energy" really are the same thing, and there is no reason to assume "space" as if it is some "real thing" (as oppose to just a semantical thing).

And what I mean with "real thing", I guess I have to talk little bit about human comprehension.

We keep asking ourselves what are the "real" fundamental "things" that exist. Ís electron fundamental? Is photon fundamental? We are amazed when we find that these small entities behave in very strange ways, and that classical causality seems to go haywire in their behaviour.

Think about that tornado again. We can imagine two tornados on the same field, affecting the paths of each others. To understand the behaviour of these two tornados and to predict how they affect each others, we can treat the tornados in our mind as real "objects", and attach certain behaviour to them. We could say we have a good theory about how tornados behave and say that tornados really exist.

But we also understand that it is not "really" the "tornados" that affect each others, but the air molecules that make up the stable pattern that we call tornado. We can say we have a good theory about how air molecules behave and say that they really exist, and we would not be the least bit surprised to find the tornados to disappear and re-appear "out of thin air", since we understand they are just patterns.

But it is not even the air molecules that "really" exist, they too are just stable patterns brought about by atoms. It is the atoms that interact with each others, causing air molecules, causing wind, causing tornado (emergent functions)

The behaviour of atoms too we have broken into smaller bits, and again it always really was just a semantical approximation to say that the "tornados interacted with each others" or "molecules..." or "atoms..."

At this end of the scale we find that the bits and pieces of the atoms don't really exist as little "real things" (referring to QM). It is naive to say what Einstein had said, that as a realist he believes atoms really exist when they are not measured. I claim here that electron is in many ways like that tornado, and the environment where it is in manifestates it in such way that it can disappear in thin air, and vice versa it manifestates the environment it is in, in such way that the things we find at a small scale are not spatially stable in the same way we find larger things to be. Electron too, is a stable pattern. I.e. it is not a "real thing", it is a "semantical thing".

Now, this business about stable patterns is not just idle talk in that it ties together nicely with philosophy of intelligence and mind (and it becomes very important to understand at that point). What we, and any animal with a brain, actually does when they try to figure out how ANY system works is that they observe stable behaviour patterns, and they classify them as objects, like one could do with that tornado. We attach a behaviour to such objects, and so we can predict how any system is likely to evolve when these semantical "objects" are present.

In such intelligence processes, whatever "objects" we understand to exist, they are always semantical objects like the tornado. It is a mistake to imagine there are some objects that are "fundamental" or "real". There is absolutely no reason to assume reality to exist that way. It is likely that there are only semantical things (albeit the stable patterns we observe are brought about by real processes).

So it is no surprise to find that "electrons" and "photons" and "matter" in small scale appears to behave so strangely. Like "space", electrons too never "really" existed. They are manifestations of some real processes, yes, but they still are just stable patterns that we chose to call "objects".

And I just cannot stress this point enough. It has such a huge implications to any ontological assertion. Reality seems to be made out of objects with identity because that is the way we "understand". We can only be aware of semantical objects. When you drive that point to its ultimate conclusion, you will notice that reality is not understandable to us in any "truly objective form" already because reality cannot be accurately classified into any semantical objects. You could imagine how the electron comes to exist due to some "forces" coming together appropriately, but again you have assumed there really exists these "forces". You are still merely investigating relationships between semantical objects.

And then it should be plain to see that space, time, and spacetime are also semantical objects. It would be very odd if they "really" existed in some naive sense of really serving as the stage for the dance between matter and light, even though we naturally comprehend this dance as if it happens in some (more or less) independent environment.

Given the above, the paper you linked to before seemed fairly interesting, but I haven't been able to give it the thought it would require... :I

 

[Aether]

Yeah, so, have I interpreted this correctly when I say that one could assume, for example, that there exists an ether if it is also assumed that the laws of physics transform accordingly to each frame (which in essence hides the ether from view?)

In which case which ever ontology you choose from these two is going to be an arbitrary choice, or down to some slightly more ambiguous criteria like "elegance"?

You are free to arbitrarily choose one coordinate-system dependent ontology from the range allowed by the laws of physics, but that would be a personal philosophical choice. I am cautioning against this, not advocating for it.

I still stand by with my assertion that it is reasonable to assume that the laws of physics really are the same in each frame, even though this is just an assumption and cannot actually be proven to be the "right way" to understand the system (After all, there are many arbitrary choices we have made in our worldview just to get this far :).

But it must be noted that I don't justify this, like most people tend to, with the geometrical simplicity of relativity or because with C against fixed ether you'd need to dream up ways to hide it, but because of, let's say "ontological elegance".

Ok, but this is your personal philosophical choice, and as you are aware it is not justified by observation.

After some thought about how we understand systems including reality, ether looks a lot like "naive realism". But so does spacetime.

Choosing either scheme as an ontology with no observational basis for making such a choice would be outside the realm of science. I am not here to advocate for making such a choice, but rather to caution against doing so prematurely.

 

[AnssiH]

Ok, but this is your personal philosophical choice, and as you are aware it is not justified by observation.

Exactly. I like to use the word "assumption" a lot, as you have probably noticed :) After all, any statement anyone can make about reality is an assumption, and any instance of trying to "prove" some statement is a case of having first assumed a particular set of "truths" which then can be said to necessarily lead to some conclusion, only they cannot be proven true themselves. And all statements about reality are made in terms of semantical objects only.

I cannot prove that world really exists; perhaps just my mind does. But I make the arbitrary assumption that world really does exist in the attempt to get further with ontology. Even though a fundamental "truth" is a non-sensical concept; any so-called "truth" can only be a matter of belief at most because of the very method with which we understand the world.

"Where man is not, nature is barren. Truth can never be told so as to be understood, and not be believed" and so on.

Choosing either scheme as an ontology with no observational basis for making such a choice would be outside the realm of science. I am not here to advocate for making such a choice, but rather to caution against doing so prematurely.

Yeah, agreed. I must keep my options open. But I also must make such statements as I did in the attempt to get further down the road of some particular flavor of ontology, to see if it leads anywhere.