What is "spacetime" really?

[modest]

Spacetime is either an abstract mathematical model, or a description of reality.

 

Can it not be both? A good model has to describe reality (or agree with observation) otherwise it never gets off the ground.

 

In the weakest gravitational fields, the only curvature is of the temporal dimension into spatial dimensions (the Riemann tensor only has non zero components in temporal components).

 

In stronger gravitational fields, according to GR space is curved as well, and the straightest distance is a "straight line" but that line will appear curved to a higher dimensional observer (4d observing a 3d slice of spacetime). This is as yet an unverified prediction.

 

I think the spatial (g_rr) component of the Riemann tensor is responsible for half the predicted deflection of light by mass and is verified in the weak field. In other words: without space curvature, light deflection and other post-newtonian tests would agree with Newton. Have I misunderstood?

 

(push button"... no post... "re-direct'... back to the above.

 

(I am so damn sick and tired of this **** that I am very nearly ready to quit this site. I log in... compose my post... the "preview" trick does not keep my post in tact... try to post, and get the above run around, having lost my editing on the "reply" screen.

I have learned to save it in phases on my notepad. However, I have not edited the notepad as I had the "reply" screen.

 

I got that error once. I hit reply and wrote my reply without submitting it. A couple hours later I returned to the computer and opened a new tab logging in again at the forum menu. I switched to the original reply tab and tried to submit it only to get that error. It’s an odd sequence of events easily avoided.

 

~modest

[Erasmus00]

I think the spatial (g_rr) component of the Riemann tensor is responsible for half the predicted deflection of light by mass and is verified in the weak field. In other words: without space curvature, light deflection and other post-newtonian tests would agree with Newton. Have I misunderstood?

 

Sorry if I mislead- in the strictly Newtonian limit of GR, only the temporal components of the Riemann tensor are non-zero.

 

In post-Newtonian weak field GR, both spatial and temporal components are non-zero, but I don't think any test of the classic tests (light bending, gravitational time dilation, perihelion precession)can unambiguously be interpreted as confirming that the shortest distance in any one constant time slice is not straight. I could be wrong.

[modest]

Sorry if I mislead- in the strictly Newtonian limit of GR, only the temporal components of the Riemann tensor are non-zero.

 

Absolutely, I agree.

 

In post-Newtonian weak field GR, both spatial and temporal components are non-zero, but I don't think any test of the classic tests (light bending, gravitational time dilation, perihelion precession)can unambiguously be interpreted as confirming that the shortest distance in any one constant time slice is not straight. I could be wrong.

 

Yeah, there probably is some ambiguity.

 

I should also agree with the point you were making to Michael, the spatial hyperslices are ridiculously flat at low velocities in weak gravity like our solar system, so that all our experiences with gravity are essentially curvature of time.

 

~modest

[jedaisoul]

Spacetime is either an abstract mathematical model, or a description of reality.

Can it not be both? A good model has to describe reality (or agree with observation) otherwise it never gets off the ground.

I would suggest that describing reality and agreeing with observations are not the same thing. Arguably, if it desribes reality, a model should also agree with observations. However, it is feasible that a model could agree with obsevations without being a very good description of reality, i.e. being correct for the wrong reasons.

[modest]

I would suggest that describing reality and agreeing with observations are not the same thing. Arguably, if it desribes reality, a model should also agree with observations. However, it is feasible that a model could agree with obsevations without being a very good description of reality, i.e. being correct for the wrong reasons.

 

I agree, and I think that gets into the philosophy of science very well.

 

Physical laws such as Newton's law of gravity or the ideal gas law don't have a theoretical structure. They simply have an equation with variables that represent real physical quantities that can be put in the equation giving some answer that should "agree with observation". While this can indirectly inform philosophy, the law itself doesn't have structure that explains what is happening in nature. As you would say: it agrees with observation, but doesn't describe reality.

 

A physical theory such as classical electromagnetism or general theory of relativity is different in that it has structure. It starts with a small set of postulates or assumptions regarding how the universe works and logically builds a framework or method for describing the universe on those postulates. In this way, it is much more useful for philosophy of science. In common parlance, a theory has power of explanation.

 

If a theory successfully and simply describes many different situations observed in the universe and it successfully predicts future observations then philosophy can look at the rules and structure of the theory and say there is something to that. The rules or the form that the model follows would seem to be the rules and form that the universe follows.

 

For example, the ideal gas law will not explain why gases heat up when compressed. It will simply tell you that it will happen. The kinetic theory of gases, on the other hand, has power of explanation. It derives predictions about the behavior of gases making assumptions about what a gas is made of and the rules of kinetic energy its composition follows. This theory then gives an explanation for the behavior of the universe which is a very powerful tool for philosophy of science.

 

~modest

[arkain101]

I understand your question. What is space-time?

 

To begin explaining lets break down the word at first.

 

If I pick two locations in the universe, they are separated by space(distance) and time (they can not interact instantly)

 

So it is fair to say that distance and time are equivalent. That is, any object that is a distance away can not be detected or interacted with, without some form of delay of time.

 

It was at a time considered that there was objects of matter, and an aether, and light energy (EM) was waves and disturbances created by objects that passes through the peculiar aether.

 

Now, when we learn about space-time it is not uncommon to think in the same mannerisms as one did with aether. That is, that the void that makes up the universe between objects and events is some kind of 3rd part to a universe with matter and energy.

 

To explain the core of space-time, I believe we have to include our very own minds and some understanding about them.

 

If we accept for a moment that space as we understand it (distance) is created by EM (light) in our minds, and is not applicable outside of our minds typical understanding of the enviroment it observes. And because of this certain levels of non-obserbable, but detectable reality can maneuver and function in ways that does not appear to operate in ways our mind understands. That is because space-time (the fabric that is not a fabric) exists only within the brain of an individual (excluding other forms of life for the moment).

,

With this accepted we can see how space-time is Electromagnetic Radiation. However, from the perspective of EM, space and time is irelevent. But the comprehension of space-time in the mind is a manifestation produced out of EM.

 

So if we say an object like earth forms a curve in space and time, we end up with a phenomina where we can walk anywhere on earth and observe we are on relatively flat ground and always standing upright. If we fly into space a curve in space in time is observed as a spherical body (from far away), and a body creates a curve in the space-time, its the same argument and in my belief it is the same thing.

 

Individually, no atom on one side of the earth can be considered to be in anyway significantly attracted to an atom on the opposite side of the earth, by any known thing we call a 'force'. So it can be fair to say that gravity is not an effect between independent atoms. Location in the universe for fundamental quantum material is irelevent because if everything is uniformly the same thing than nowhere can be any different. It is our awareness that realizes the many endless atoms that form the earth, and its apparent unique location in the universe.

 

This does not mean that our mind has the power to hold the universe together, it means that the mind creates something that would otherwise be entirely meaningless at other levels of reality. That something is space-time.

[Rade]

If I pick two locations in the universe, they are separated by space(distance) and time (they can not interact instantly)

Suppose I have a proton (+) at point P in the universe and an electron (-) at point E, and the two are just less than one light year away. Will they not 'interact instantly' via gauge photon ? So, I think what you say next is not correct:

So it is fair to say that distance and time are equivalent. That is, any object that is a distance away can not be detected or interacted with, without some form of delay of time.

.

Distance (D) and time (T) are not 'equivalent', that is, D does not = T. They are similar to each other only to the extent that they are both a concept of that which is 'intermediate' between two things, time being that which is intermediate between two 'moments', and distance (or space) being that which intermediate between two 'existents'. So, then I cannot also agree with this idea you present:

If we accept for a moment that space as we understand it (distance) is created by EM (light) in our minds

I do not accept that 'space' is created 'in our minds', no more than I can accept that existence is created within the mind. The only thing the human mind creates are concepts, it does not create space or time. Now one can take a concept and then create a new thing that exists from it--it is called invention. Finally I do not agree with this statement you make

it means that the mind creates something that would otherwise be entirely meaningless at other levels of reality

The concept of space-time is not meaningless to plants and animals, it is not a human invention. Consider how the bat survives, space and time have great meaning to the bat.

[Michael Mooney]

OK folks, I'm going back to the basics of my ontological inquiry into spacetime.

You assume the reality of space being something that can have shape, curvature, and that time is something that can go slower or faster or be curved. These assumptions are again evident in Modest's statements:

I should also agree with the point you were making to Michael, the spatial hyperslices are ridiculously flat at low velocities in weak gravity like our solar system, so that all our experiences with gravity are essentially curvature of time.

 

~modest

 

The cosmic perspective which I call objective * is not limited to relativity theory* (see my post #114 with the briefest summary of my understanding of GR and SR) is that It is always now everywhere. This has nothing to do with observations from local perspectives limited by lightspeed.

Please explain how you are *not* erroneously reifiying "time" once you understand that there is no time between past and future, neither of which are present. Time is indeed the observed duration of a given "event", but all events happen in the ongoing present. There is no time in the present, and it is always the present.

 

Likewise space is the emptiness between objects *in space.* It is endless volume with *no properties*... unless you call emptiness a property.

 

There has been no response whatsoever to my persistent focus on the forces acting on clocks and calling for sincere investigation as to the dynamics of their slowing down when subjected to the forces of inertial change. Rather you keep parroting the reified version of time as dilating, having curvature, etc.

Space: You deny the "objective" measure of distance from earth to sun... well known to be around 93 million miles or 8+ light minutes. You seem obsessed with local perspectives, including the "thought experiment" as though a photon "experiences" no time or space in its journey between the two bodies. You refuse to even consider that space might indeed be emptiness, the the actual distance between things, in linear mode, i.e., not subject to curvature. You seem brainwashed by relativity theory, to the extent that you can not or will not even consider for a moment the possibility that what I have said above is true.

 

No one has given a reasonable explanation of the two cases of non-Euclidean space (spherical or hyperbolic) as hving any observable referents (or making any sense) in the real world.

 

Is the shortest distance between two points a straight line or a curved one? (Duh!)

Can parallel lines ever converge? If they do they are not parallel. *Duh!) Any reply to the above. Anyone willing to address the paper I so carefully critiqued putting math in perspective as wel las the leap to non-Euclidean space.

 

Just a repetition of my favorite as yet unanswered questions/challenges.

 

You go off on technical tangents without reply to these challenges.

 

I'll leave it here for now. Back later or tomorrow.

Michael

[Essay]

Sure it's always "now everywhere" conceptually, but that's not the same as simultaneity everywhere. "Nows" are relative to the observer, aren't they?

 

"No one has given a reasonable explanation of the two cases of non-Euclidean space (spherical or hyperbolic) as having any observable referents (or making any sense) in the real world." -MM

Isn't the ocean's sense of "down" an example of this? ....Parallel lines projecting down from a flat surface, all intersecting at the center of the earth.

 

...also you ask: "Is the shortest distance between two points a straight line or a curved one?" -MM

Well in a stong gravity field, a curved line (following the curve of equipotential) would be the shortest distance, wouldn't it?

...or am I thinking of work (not distance)

...but isn't it relative to the observer? That curve of equipotential would appear flat to someone riding on it, wouldn't it?

===

 

 

Michael, you don't have to commit to accepting a new definition or concept, but you should be willing to provisionally try a few new ideas that go beyond the common sense of everyday "middleworld."

 

May I try another image that might tie up the loose ends of these definitions about spacetime and matternergy.

 

First, start with the point of infinite density which generated the bigbang. Whatever this was, it is the source of our matternergy.

 

Okay, so this spot is surrounded by your infinite void of nothingness (what you are equating with empty space).

 

Then as the spot goes bang and expands, inflates, or explodes out like a firework, the solid bits fly apart from each other.

 

Now for this image to work, we must keep the "void" outside of the initial spot, withdrawing away from the bigbang as it expands; thus the explosion does not expand into the void, but pushes the void away....

 

Just think of the bigbang as all solid, and remaining solid as it explodes outward, pushing the void evenly away from the expanding outer surface of this expanding solid sphere that is (for this image) the bigbang.

===

 

But all the solid stuff that was initially touching (if we think of it as all still solid) is still touching as it expands outward, replacing the void outside of the bigbang.

 

But it's not a solid sphere (at least it doesn't appear to be so).

But if we keep that "solid" image, and substitute a new tenuous touching of all the initial matter (as it continues to expand outward), then the solid becomes like an exploding firework of solid bits and lots of tenuous smoke filling the generated volume that develops as expansion occurs.

 

Spacetime is the smoke, the rarified bits of bits (that are really still all touching) that just appears to be emptiness between the flying sparks.

 

IMO spacetime is not the emptiness between the bits.

It is the last remaining traces of connectedness between the solid bits.

As such it contains information about the solid bits; and if the bits change, then that trace of connectedness reflects the change.

 

This is why I like to say that matternergy generates spacetime (or spacetime is an artifact of matternergy).

 

It is the act of change by matterenergy that leaves spacetime in it's wake.

 

Without any change (no bigbang, expansion, or turbulence) there would be no tenuous connection between the things changing--no spacetime. Each change creates more spacetime.

===

 

Matternergy expands ourward dragging its history and connections (spacetime) along with it ...to replace the void.

Spacetime can not exist at any given location unless matter or energy has once been there to create it.

===

 

So Michael, can you imagine the bigbang replacing the void rather than just expanding out into and through the void? It would be as if the void and the bigbang were immiscible, like water and oil.

 

Spacetime is just an expression of the heterogeneity of matternergy.

I'm hoping this weird image of a solid that is not a homogeneous solid anymore, will suggest a new definition to you of something (spacetime) that "looks like a void" but is filled with history, potential, and change--the remains of matter or energy that once passed by.

 

~? :phones:

[Michael Mooney]

Essay:

Sure it's always "now everywhere" conceptually, but that's not the same as simultaneity everywhere. "Nows" are relative to the observer, aren't they?

 

From what I "see" as cosmic perspective (see my "thought experiment" earlier in this thread) event duration is a secondary consideration, whether one is considering a full "bang/crunch" cycle, the "elapsed time" since the last Bang or a single earth rotation or orbit (day or year.) Beyond what can only be called the scientific obsession with event duration, the present is always, perpetually now everywhere. Such cosmic perspective is

not

the relative perspectives of different observers in different locations. Yes now is simultaneous and omnipresent from cosmic perspective.

 

Isn't the ocean's sense of "down" an example of this? ....Parallel lines projecting down from a flat surface, all intersecting at the center of the earth.

 

From cosmic perspective as well as common sense earth geometry the ocean's surface is not (In my proposed cosmologyflat but curved as per the nearly spherical earth we all know and love. True parallel lines would pass through the whole globe and come out on the other side still parallel and out into endless (Inspace forever parallel.

 

Well in a stong gravity field, a curved line (following the curve of equipotential) would be the shortest distance, wouldn't it?

...or am I thinking of work (not distance)

...but isn't it relative to the observer? That curve of equipotential would appear flat to someone riding on it, wouldn't it?

 

Gravity curves the trajectory of objects traveling through space, not space "itself", which, from cosmic perspective, is endless emptiness, volume without defining shape or boundaries. A curved line is not a straight line in any case. And, again cosmic perspective transcends local perspectives.

Michael, you don't have to commit to accepting a new definition or concept, but you should be willing to provisionally try a few new ideas that go beyond the common sense of everyday "middleworld."

 

I have in fact studied both GR and SR in some depth, sans mathematical expertise. They are not "new ideas." By the same token, I am, in this thread, asking for folks to give my "thought esxperiment" in "cosmic perspective" a fair chance as perhaps a "new idea" transcending the thought experiments central to relativity, especially as it pertains to local perspectives as seen by different observers. (Cosmic perspective "sees" cosmos as a whole as from the perspective of one omnipresent observer. (No religious connotations intended.)

 

First, start with the point of infinite density which generated the bigbang. Whatever this was, it is the source of our matternergy.

 

Okay, so this spot is surrounded by your infinite void of nothingness (what you are equating with empty space).

 

Then as the spot goes bang and expands, inflates, or explodes out like a firework, the solid bits fly apart from each other.

First, a "point" has no volume and therefore can not contain anything, much less all cosmic matter/energy/plasma. The bang, from cosmic perspective would issue from a ball of whatever size of matter compacted as much as possible, but short of "infinite density."

 

This ball (or series of balls... with a phased multiple bangs-and-crunches model ) then "goes bang" exploding actual materials out into the infinity of empty space

 

Now for this image to work, we must keep the "void" outside of the initial spot, withdrawing away from the bigbang as it expands; thus the explosion does not expand into the void, but pushes the void away....

 

Just think of the bigbang as all solid, and remaining solid as it explodes outward, pushing the void evenly away from the expanding outer surface of this expanding solid sphere that is (for this image) the bigbang.

 

In my proposed cosmology, Space, being emptiness, is the endless void and not effected by that which explodes and implodes *in it*... as per a perpetual bang/crunch cycle. Emptiness is infinite no-thin-ness and does not "expand."

 

((skipping down to your conclusion... as the above addresses your points in between):

So Michael, can you imagine the bigbang replacing the void rather than just expanding out into and through the void? It would be as if the void and the bigbang were immiscible, like water and oil.

 

Spacetime is just an expression of the heterogeneity of matternergy.

I'm hoping this weird image of a solid that is not a homogeneous solid anymore, will suggest a new definition to you of something (spacetime) that "looks like a void" but is filled with history, potential, and change--the remains of matter or energy that once passed by.

So, Essay, I must turn it back to you. Can you imagine the cosmic perspective again presented here with space being true emptiness and all observable phenomena being cosmos, actual "stuff" *in space? If so, no-thing-ness remains emptiness with *no properties at all* while all "properties" per se belong to the "stuff-in-space."

 

Michael

[modest]

OK folks, I'm going back to the basics of my ontological inquiry into spacetime.

You assume the reality of space being something that can have shape, curvature, and that time is something that can go slower or faster or be curved. These assumptions are again evident in Modest's statements:

In order to understand the assumptions and statements I've made regarding the analogies of shape and curvature, it would be necessary to understand the observations of relativity. There are many internet and non-internet sources that would help with this. It is usual to start with special relativity, where I would recommend:

• 
  
• Wikibook on special relativity.
  
• Understanding Relativity: A Simplified Approach to Einstein's Theories by Leo Sartori, 1996
  

The cosmic perspective which I call objective * is not limited to relativity theory* (see my post #114 with the briefest summary of my understanding of GR and SR) is that It is always now everywhere. This has nothing to do with observations from local perspectives limited by lightspeed.

This has a name. It is called Galilean (or Newtonian) relativity. It's nothing new, and it has been proven wrong. I understand if you like it philosophically, or that it makes sense to you. But, that doesn't make it right, and we've known for about 100 years that it is wrong.

 

Please explain how you are *not* erroneously reifiying "time" once you understand that there is no time between past and future, neither of which are present.

Relativity does not demand there be "time between past and future".

 

Time is indeed the observed duration of a given "event",

 

An event in spacetime and an event in philosophy has no duration.

 

Likewise space is the emptiness between objects *in space.* It is endless volume with *no properties*... unless you call emptiness a property.

 

"Endless" and "empty" do not explain space. An object has height, width, and depth. "Endless" and "empty" don't explain such an object. They don't describe the relationship two objects with height, width, and depth have with one another. "Empty" doesn't explain or describe distance and certainly doesn't explain and describe gravity or motion.

 

There has been no response whatsoever to my persistent focus on the forces acting on clocks and calling for sincere investigation as to the dynamics of their slowing down when subjected to the forces of inertial change.

 

An inertial force (or pseudo force) cannot be responsible for time dilation. To understand why would require some familiarity with inertia, forces, and time dilation. It is not just clocks that are time dilated. It is all physical processes: a clock, a metronome, a decaying muon, an hour glass, cell mitosis, a person counting to 5, etc.

 

Two such things that are time dilated relative to one another may feel no inertial forces. Time dilation is proportional to relative velocity, not acceleration. So, time dilation cannot be an effect of inertial forces.

 

Space: You deny the "objective" measure of distance from earth to sun... well known to be around 93 million miles or 8+ light minutes.

 

I don't mean this as a criticism, but you appear not to understand the most basic concepts of relativity. If you don't understand why there is no absolute distance between the earth and sun then how can you object to the distance being relative?

 

You seem obsessed with local perspectives, including the "thought experiment" as though a photon "experiences" no time or space in its journey between the two bodies. You refuse to even consider that space might indeed be emptiness, the the actual distance between things, in linear mode, i.e., not subject to curvature. You seem brainwashed by relativity theory, to the extent that you can not or will not even consider for a moment the possibility that what I have said above is true.

 

Your claim has been considered by everyone. It was the default scientific position until 100 years ago. It has been argued on this forum by scores of people. It is called Galilean invariance or absolute Newtonian space, and it has been proven wrong experimentally. No one is failing to grasp what you're saying, we simply know it is wrong.

 

~modest

[Erasmus00]

Michael, can I suggest the following? sit down with your cosmic observation frame, and starting from this assumption start deriving some physical consequences. What you will find is that you CANNOT, from this frame, create a self consistent physics that also describes reality. Try it.

-Will

[Essay]

Hiya Michael,

Good answers to all those points. The ocean surface was a pretty lame example, but in both cases (ocean + strong gravity field) you did need to invoke your "cosmic perspective." At least with the gravity example, I did specify local perspective....

 

I think I've kept up with all the posts here, but which post # is the specific "thought experiment" that you're talking about. I'll go look at that again.

===

 

...but for now I'll just comment on these points here:

 

"Such cosmic perspective is not the relative perspectives of different observers in different locations. Yes now is simultaneous and omnipresent from cosmic perspective." -MM

 

I used "simultaneity" to speak to the interactions between things and the measurements that can be made on these things.

Sure (I think anyone would agree) from a cosmic perspective there is the universal now; but in terms of a scientific perspective, the term "now" just isn't very useful.

 

I guess I don't understand how your observation that the "Cosmic perspective "sees" cosmos as a whole as from the perspective of one omnipresent observer" is useful to any real observations, measurements, or studies of interactions that can be made.

 

I realize you're familiar with SR and GR, but when you say that,

"In my proposed cosmology, Space, being emptiness, is the endless void and not effected by that which explodes and implodes *in it*...."

aren't you just back to the Newtonian version of reality?

 

You ask me:

So, Essay, I must turn it back to you. Can you imagine the cosmic perspective again presented here with space being true emptiness and all observable phenomena being cosmos, actual "stuff" *in space? If so, no-thing-ness remains emptiness with *no properties at all* while all "properties" per se belong to the "stuff-in-space."

YES!

Of course I can. Everyone can. It is "the common sense of everyday 'middleworld'."

It is a view that contradicts nothing with which we are familiar (in our limited experience).

Even a 6-year-old has enough experience to understand this common-sense view of reality.

That is what I thought you must picture, and is why I wrote "...rather than just expanding out into and through the void," ...after asking if you could imagine my scenario.

===

 

So does this mean that semantics is the problem?

 

You say:

...while all "properties" per se belong to the "stuff-in-space."

 

So are you talking about fields (emmanating from the "stuff-in-space") as being the source of these "properties?"

===

 

:)

...and in which post did somebody already talk about Field Theories?"

 

Thanks MM!

bbl

 

~ SA

[Michael Mooney]

Modest,

Your last reply to me was a blatantly pompous appeal to authority totally ignoring my opening statement:

In answering, you may correctly assume that I have thorougly studied the background of the "spacetime" component of relativity theory. Yet the actual nature of the "medium" (or whatever it is *supposed* to be) has never been explained to my satisfaction.

.... and many similar references to my understanding of GR and SR, most recently in reply to Essay:

I have in fact studied both GR and SR in some depth, sans mathematical expertise. They are not "new ideas." By the same token, I am, in this thread, asking for folks to give my "thought esxperiment" in "cosmic perspective" a fair chance as perhaps a "new idea" transcending the thought experiments central to relativity, especially as it pertains to local perspectives as seen by different observers. (Cosmic perspective "sees" cosmos as a whole as from the perspective of one omnipresent observer. (No religious connotations intended.)

 

Yet you say:

In order to understand the assumptions and statements I've made regarding the analogies of shape and

curvature, it would be necessary to understand the observations of relativity.

... and cite sources which I have gone far beyond in the course of my study.

 

Then you respond to my reiteration of my familiarity with relativity:

The cosmic perspective which I call objective * is not limited to relativity theory* (see my post #114 with the briefest summary of my understanding of GR and SR) is that It is always now everywhere. This has nothing to do with observations from local perspectives limited by lightspeed.

.... saying:

 

This has a name. It is called Galilean (or Newtonian) relativity. It's nothing new, and it has been proven wrong....

(Your first pompous-appeal-to-authority.)

 

I am familiar with Galilean/Newtonian relativity... specifically with the statements in the links you cited above:

Albert Einstein's central insight in formulating special relativity was that, for full consistency with electromagnetism, mechanics must also be revised such that Lorentz invariance replaces Galilean invariance. At the low relative velocities characteristic of everyday life, Lorentz invariance and Galilean invariance are nearly the same, but for relative velocities close to that of light they are very different.

 

(Sartori's) Understanding Relativity is a textbook....

It begins with Galilean relativity and the Michelson-Morley experiment, then presents the basic postulates of relativity, Lorentz transformations, space time diagrams (including Loedel diagrams, which were new to me), and some of the standard "paradoxes".

 

You continue to misunderstand my fundamental challenge here. Given that " Lorentz invariance (claims to replace) Galilean invariance. (and that)... "At the low relative velocities characteristic of everyday life, Lorentz invariance and Galilean invariance are nearly the same..."

 

The Lorentze transformation *assumes* time dilation and space curvature, both of which are clearly cases of erroneous reification, as I have meticulously argued in this thead. I have recognized the improvements in gravitational predictability via relativity with alternative explanations for the medium between gravitation generating masses (i.e., across *empty" space rather than "bending space" and "dilating time." You conveniently ignore all my arguments in this regard and glibly state that Galilean/Newtonian relativity" has been proven wrong"... without specifics to back up the claim.

 

You cited "one of your favorite philosophers" (who I reviewed in depth) who brought some serious criticisms against the transition from Euclidean to non-Euclidean space *upon which the Lorentz invarience ... and transformations... are based, yet you now sweep those (and my) objections under the rug as having been debunked for a hundred years now.

 

You say:

Relativity does not demand there be "time between past and future".

This is totally bogus. "Presentism", as you know is the *realization* that "time" is a human artifact, that, indeed "it is always now... everywhere." "Time dilation" is therefore a reification of time and a central principle of relativity.

To my:

Time is indeed the observed duration of a given "event",

...

you replied:

 

An event in spacetime and an event in philosophy has no duration.

 

I use "event duration" in its obvious meaning of "elapsed time" between the beginning and ending of observation of a designated "event" and have given many examples of such "events", from the 8 minute journey of sunlight to earth to a day, a year and a complete cosmic "bang/crunch" cycle.

I understand the usage of "event" in the "spacetime" paradigm as locating a phenomenon by its three spacial and one temporal coordinates. Please get over your condescension based on "correct scientific usage" as so superior to my general, common sense usage of such terms as "event duration!"

You say:

Endless" and "empty" do not explain space. An object has height, width, and depth. "Endless" and "empty" don't explain such an object. They don't describe the relationship two objects with height, width, and depth have with one another. "Empty" doesn't explain or describe distance and certainly doesn't explain and describe gravity or motion.

 

What amazing and arrogant condescension! Everyone with a brain understands 3-D space and the common usage of "time" as a "fourth dimension.

We already went a couple of 'rounds' on your insistence that space can not be simply the void without objects. I have never claimed to know how gravity works across empty space, for instance, but only that positing a mysterious medium to convey forces across space adds nothing to our understanding of the forces in question. The "objects" in space are the proper "objects" of scientific study, not some replacement for the old "aether" theory of transmission.

 

Light years (seconds, minutes, etc.) describe distance very well without such a mysterious medium as spacetime between "events." So do miles, kilometers, etc. Positing "spacetime" (instead of "aether" doesn't "explain" gravity or motion either.

 

Time dilation is proportional to relative velocity, not acceleration. So, time dilation cannot be an effect of inertial forces

Prove it. "Time" is not "real." (See above, and my many references to the omnipresent now in relation to event duration (time.)

Of course you are consistently referring to "time dilation" as a given... long ago "proven" and no longer deserving of thoughtful consideration.

The actual difference in forces upon the speeding clock and the control clock, in all cases, is that the former has been "forced" to speed up and slow down, both changes in inertia. I suspect that human metabolism also slows down under exposure to the forces of acceleration /deceleration.

 

don't mean this as a criticism, but you appear not to understand the most basic concepts of relativity. If you don't understand why there is no absolute distance between the earth and sun then how can you object to the distance being relative?

More condescending arrogance. (Not criticism, of course.)

 

I understand and disagree. (You give lip service to questioning authority, as per the author of the ontology piece we both like)

 

I understand that from cosmic perspective, or even a deep space photo of sun and earth that there are are approximately 93 million "miles" (however many kilometers), each standardized earth-commensurate measures of distance. between the two bodies. You can do "thought experiments with a "photon's experience of 'no time or space' in its travel until you talk yourself out of this objectiv measure of the distance, but it remains all in your head, while the actual distance is ontologically real.

 

Your claim has been considered by everyone. It was the default scientific position until 100 years ago. It has been argued on this forum by scores of people. It is called Galilean invariance or absolute Newtonian space, and it has been proven wrong experimentally. No one is failing to grasp what you're saying, we simply know it is wrong.

Everyone? Really! The epitome of scientific appeal-to-authority arrogance!

Please review my post critiquing of the transition to non-Euclidean geometry, and the attending critique of the limits of math as a descriptive tool of observable cosmos... as the assumed basis fo rthe "proof" you are claiming.

Hope to get to other replies soon.

Michael

[Michael Mooney]

Erasmus:

Michael, can I suggest the following? sit down with your cosmic observation frame, and starting from this assumption start deriving some physical consequences. What you will find is that you CANNOT, from this frame, create a self consistent physics that also describes reality. Try it.

 

What kind of physical consequences.are you suggesting. That masses pull on each other as per Newton's law and that there are anomalies in Mercury's orbit better explained by the math of general relativity than Newtonian relativity. That they are the same but for phenomena approaching lightspeed.

That absolute cosmic" time" (actually timelessness) transcends observations limited by lightspeed ?

 

I think that science will soon find the bridge between the quantum effect of interaction between entangled particles *at a distance* and masses' pull on each other *at a distance* without positing the miracle-fabric "spacetime" as a medium required for these forces.

 

Maybe if you were more specific about what I CANNOT create as a physics which describes reality...

Michael

[Michael Mooney]

Essay,

My original presentation of the "cosmic perspective" (and timelessness in the universal now) was early on but irrelevant if you dismiss my reiteration of it as below:

 

.... Can you imagine the cosmic perspective again presented here with space being true emptiness and all observable phenomena being cosmos, actual "stuff" *in space? If so, no-thing-ness remains emptiness with *no properties at all* while all "properties" per se belong to the "stuff-in-space."

 

... with the following brush-off:

 

YES!

Of course I can. Everyone can. It is "the common sense of everyday 'middleworld'."

It is a view that contradicts nothing with which we are familiar (in our limited experience).

Even a 6-year-old has enough experience to understand this common-sense view of reality.

That is what I thought you must picture, and is why I wrote "...rather than just expanding out into and through the void," ...after asking if you could imagine my scenario.

 

"Middleworld" indeed! Do you think that a six year old understands that all matter in the cosmos can not be contained in a point of no volume. Maybe. Can you? Do you think that the ontology of truly empty space, "the void" is now obsolete, replaced by the "spacetime continuum" which inflates (faster than light after the "bang") and then magically produces all all cosmic material "later on" and the "nothingness" of space recedes with the expansion of the cosmos? I imagine your scenario as positing a reified version of space with the properties of expandability, curvature, etc... all the "blessings" of non-Euclidean space as tailored to all theories supposedly debunking all Euclidean based cosmology. (Observe-ability or making sense no longer a scientific requirement as long as the math works out to fit the theoriies. See how bazaar M-theory is with between 11 and 26 "dimensions"... but the equations really impress the mathematicians who "understand" the theory. )

 

So are you talking about fields (emanating from the "stuff-in-space") as being the source of these "properties?"

Yes, without the "medium" between required by scientific materialism.

 

aren't you just back to the Newtonian version of reality?

 

Not quite. Newton didn't "like" "action at a distance" either. See my comments above to Modest comparing Newtonian relativity and general relativity.

The advantage of the latter is in dealing with *extremely* large scale gravitational effects and relative observation of events dependent on lightspeed.

I *know* that gravitational force is *steady* among all masses but of course decreasing in force with the square of the distance between them . However *changes in gravitational force" travel (through the void of space) at lightspeed. (See the Homann observations of the periodic Sirius A and B alignment as slowing earth's rotation speed.)

 

and in which post did somebody already talk about Field Theories?"

 

I dunno, but what kind of field do you think transmits information *instantaneously* between entangled particles which are quite far apart... no limit yet found? Hmmm... looks like that old bugaboo "action at a distance" rearing its ugly head again!

 

Gotta go. See ya later.

Michael

[Essay]

Hiya Michael, ...thanks for the nice reply....

 

Sorry... wasn't meant as anything ...anymore than asking me if I could imagine....

But I really did enjoy your "Middleworld" indeed! paragraph. ...good motivation! :)

 

Regardless of what a kid might know about geometric points, I didn't meant to get into a thing about a dimensionless point (and I did soon change to calling it a "spot").

 

But it got me thinking about the "infinite density" description.

 

I was thinking that, viewed from "outside," our current universe might still appear to be infinitely dense.

It might even still appear to be pointlike or "a ball of whatever size of matter compacted as much as possible, but short of "infinite density."

 

It'd be pretty hard to measure ...and all fairly relative....

===

 

You ask:

"...what kind of field do you think transmits information *instantaneously* between entangled particles which are quite far apart... no limit yet found? Hmmm... looks like that old bugaboo "action at a distance" rearing its ugly head again!" -MM

 

Yes, well this is why I think everything is still touching, and that spacetime is a derivative effect, an illusion, or an artifact based on the interaction of all those still touching things.

 

Somewhere... they're still all touching... whether it is through other dimensions, or within Mbranes, or within the mind of God....

 

We just don't understand space well enough yet, ...or the dimension of intention.

 

Cheers,

~ :)