What is "spacetime" really?

[Boof-head]

Spacetime is what you have left when you subtract Newtonian space and time (and all of the information in it).

[Buffy]

Spacetime is what you have left when you subtract Newtonian space and time (and all of the information in it).

 

Subtract it from what?

 

No wonder you're late. Why, this watch is exactly two days slow, :eek2:

Buffy

[Boof-head]

Subtract it from what?

Well, when you gauge all the mass information as a general curvature tensor G(uv), which encodes a symmetric tensor g(uv) = g(vu), you can "subtract it" by simply moving it to the edge of the universe (which is at infinity).

 

Then you have a space left, with "energy" in it = T(uv). This energy information can also be shifted to the edge, but you have to put G(uv) back.

Then you can calculate what's left - when you make Newtonian space and time "vanish", by diagonalising a 4x4 Lorentz transform as a 2x2 Minkowski tensor; (2,0) Minkowski space is of "frequency", not time or space.

 

So, I'm not late, and I'm not early either. I'm "just a timeless frequency".

[Boof-head]

Yeah, that means Newtonian distances are in space and time = information; mass is measured as a 'fixed' distance, energy as 'motion'.

Minkowski space is independent of these, so is information-independent.

 

There is no way to transmit information unless you have real Newtonian time + space.

[Michael Mooney]

Your final quote in the last post has nothing moving relative to anything else. It has nothing to do with relativity. Obviously the people on earth will determine that the distance is about 149 million km. We just got done discussing that. You state as fact that such a distance is universal, objective, absolute, etc. But, you do nothing to support that view.

 

Can you follow my thinking when I say velocity is not universal and absolute? What, for example, is the velocity of Mars? There's no universal answer to that question. Velocity is only useful as a concept when it is compared to something else. Is this correct, do you follow?

 

If you disagree then let me know what the absolute and universal velocity of Mars is.

 

~modest

First, before point by point reply, you continue to completely avoid my repeated ontological inquiry/challenge, most recently stated in the following reply to JMJones:

 

So, as you acknowledged, the distance between sun and earth does not actually change during the observations from different perspectives/velocities in the four situations at hand here, but rather the relative perception and its measurements change with relative velocities, etc. "Relative" to the actual distance between the bodies, which remains the same, this could be called "observer error" even while trajectory calculations are vastly more accurate using the improved math tools of relativity.

 

Most recently I appealed to you again:

Please give some serious attention to the ontology which is the focus of this thread as an inquiry into what might be objectively real independent of what can be observed from relative perspective.

This again asks the question, "Do you think subjective perception (relative to position, velocity, lightspeed, etc) creates reality, or is there an objective cosmos independent of relative perception of it. (I must and will always reject philosophical, subjective idealism as the creator of the cosmos and final word on actual distances between cosmic bodies. Back to the cliche' example...

I will not accept the negation of the sound waves caused by "the tree falling in the forest" on the grounds that "ears" do not hear it. You totally, absolutely refuse to answer this often repeated challenge to the "philosophy of science" which makes relativity (quite ironically) the absolute definition of what is real and true of the cosmos.

 

Now, I am not clear whether my "final quote" to which you refer abover is the one reiterated in the quote box above or the following:

 

It may seem "convenient" to believe that humans and their observations and measurements in the relativistic paradigm define the ultimate nature of the reality of the universe, but I have consistently contended that this is not so, and the "objective cosmos" as I know it... through whatever unscientific means... can not be dismissed out of hand as disproven by the success of relativity in its own paradigm.

Space can remain that through which objects, of whatever speed and trajectory travel, independent of relative perspectives. Time can remain the elapsed time of any/all events independent of human-contrived units of measure or methods of measurement.

 

The final statement above states the obvious fact that objects of various velocities and trajectories do move through space.

 

Specifically, you wrote:

Your final quote in the last post has nothing moving relative to anything else

.

 

I have repeatedly referred to the irregular orbits of planets (*relative sun/planet motion*) causing variation in distances between them and the sun. This in contrast to relative points of view causing said distances to change.

 

You continued:

 

It has nothing to do with relativity. Obviously the people on earth will determine that the distance is about 149 million km. We just got done discussing that. You state as fact that such a distance is universal, objective, absolute, etc. But, you do nothing to support that view.

 

I state as fact that observation, regardless of viewpoint does not have the power to make earth (or other planets) move closer to or further from the sun.

Do you agree with this or not?

To state that relative perception actually makes such objects move closer or further apart is a logical absurdity and beyond the pale of all reason. It assumes that "it is all in our minds", all dependent on perceptual point of view, that there is no cosmos in an objective and perception-independent sense. Answer this if you will.

 

Finally, re:

What, for example, is the velocity of Mars? There's no universal answer to that question. Velocity is only useful as a concept when it is compared to something else. Is this correct, do you follow?

 

If you disagree then let me know what the absolute and universal velocity of Mars is.

I have "seen" the expanding cosmos in vision my whole life. Relative to the locus of origin of this expansion, the velocity of Mars away from this locus is about the same as the velocity of our galaxy in its trajectory outward from "the Bang." I agree that there is no universal answer in the above perspective. I do agree that "Velocity is only useful as a concept when it is compared to something else" (i.e., velocity relative to what?)Yes, I do follow.

However, the velocity of the Martian orbit around the sun is well known as is Earth's orbital velocity. I assume you agree, so will not look it up and quote it. So are their average orbital distances from the sun.

Here you clearly disagree, though these distances comprise a well accepted and established body of scientific knowledge... a fact which you have so far avoided addressing. These orbits do change velocity as they "swing" faster or slower around on their variable length gravitational (centripetal) "tethers", (in balance with their tangental momentum of centrifugal force.) This is the well known "slingshot" effect... and this is just factual physics, not variation caused by observation , which is the basis of your "absolute" relativity assumption.

 

I hope the above is clear. If not I am very willing to clarify in reply to specific questioning.

Michael

[Michael Mooney]

JMJones:

MM- Please accept my apologies, as I seem to have provided support for views that are not correct. Let it be known, that if anything I say disagrees with anything modest says, than most likely I am wrong....

 

Nothing is independent of what can be observed from relative perspective. There is no unique frame of reference. There is no objective reality except that all reality is subjective to perception.

 

I believe your "apologies" are disingenuous.

 

For someone who defers so completely to "authority" on the subject at hand you seem quite sure that your (and Modest's) personal opinion is beyond opinion and in fact "correct" in contrast to my "incorrect."

 

You clearly subscribe to a "philosophy of science" based on subjective idealism. Is it really "all in our heads" and totally dependent upon what our eyes can see, limited as they are by the speed limit of light? Would the cosmos disappear if humans never evolved to observe it an opine that our observation creates it?

I think not.

You wrote:

I agree with your assessment that the sun does not magically become 30,000,000 km closer in example B. Therefor, the problem is that the observer in B could not have possibly measure 500 seconds, proving that time is relative to velocity.

 

I replied:

So, as you acknowledged, the distance between sun and earth does not actually change during the observations from different perspectives/velocities in the four situations at hand here, but rather the relative perception and its measurements change with relative velocities, etc. "Relative" to the actual distance between the bodies, which remains the same, this could be called "observer error" even while trajectory calculations are vastly more accurate using the improved math tools of relativity

 

There is no question that "time is relative to velocity." Time is one of the two major components of velocity, as we all know... "miles per hour." How does this make the actual distances between actual bodies in space change. It doesn't!

 

Care to clarify what you meant by: "I agree with your assessment that the sun does not magically become 30,000,000 km closer in example B.?"

Michael

[Erasmus00]

Sorry that I flit in and out of this, but I feel often that I've said all I need to say.

 

Michael, you are confusing two things- saying that distance measurements change relative to an observer is NOT the same thing as saying that "an observer creates reality" or "there is no objective reality."

 

In relativity, instead of a distance AND a time that everyone can agree on, there exists a combination [imath] s^2 = d^2-t^2[/imath] that everyone can agree on. Here d is the distance between two events, and t is the time between two events. It is this measurement that is "objective," and because its a combination of space and time, this is essentially what we mean when we say spacetime.

 

Further, the "point" of general relativity is that there exists an objective reality HOWEVER, all our measurements are just labels. Physics, real physics, should be independent of these labels, since the labels are subjective. To make this brilliant insight actually work, however, you have to develop some sophisticated math- but math doesn't exist in a vacuum. It implies physical things about the universe- the math of general coordinate invariance(subjective labels don't matter) implies that the universe is a curved, 4 dimensional manifold.

 

Finally, I leave you with Modests thought experiment, worked out yet again, because I want to make a clear point.

 

Consider a space ship that takes off from Earth moving at 1/2c toward the Moon (c being the speed of light). At the same instance, Earth sends out a light beam towards the moon. (for this problem, the moon will be 1 light second away). The beam bounces off a mirror on the moon and returns to the Earth.

 

From the Earth's frame, the light takes 2 second round trip. At 1.25 seconds on Earth, the light beam travels past the ship (the light on its way back, the ship on its way to the moon). So Earth says "we have measured the distance to the moon to be 1 light seconds away." And it knows when the ship passed the light beam, the moon was .25 light seconds from the ship.

 

Now, from the ships frame, whats the situation look like? The ship has traveled 1.25 seconds when it sees the light beam right? But now there is a new effect, the ligth beam comes back blue shifted, so the ship can say "aha, I know the moon is moving relative to me at 1/2 c."

 

So the captain of the space ship reasons "the total distance the light traveled was the twice the distance from the the ship to the moon, minus the distance the moon moved." This formula is 2d-1/2c = 1.25 light seconds. Solving for the distance between the ship and the moon we get d = .875 light seconds. Something is very wrong! The distances measured by the ship and the Earth do not agree.

 

Why is this Michael?

[Pyrotex]

First, before point by point reply, you continue to completely avoid my repeated ontological inquiry/challenge...

"Do you think subjective perception (relative to position, velocity, lightspeed, etc) creates reality, or is there an objective cosmos independent of relative perception of it. (I ...reject ...subjective idealism as the creator of the cosmos and final word on actual distances between cosmic bodies. ...You totally, absolutely refuse to answer this often repeated challenge to the "philosophy of science" which makes relativity (quite ironically) the absolute definition of what is real and true of the cosmos.

...

You continued:

"I state as fact that observation, regardless of viewpoint does not have the power to make earth (or other planets) move closer to or further from the sun."

Do you agree with this or not?

To state that relative perception actually makes such objects move closer or further apart is a logical absurdity and beyond the pale of all reason.

...

 

Michael,

hi. I'm a "propeller-head" down at the NASA Johnson Space Center. Though my work here involves mostly software engineering, I am well-versed in rocket science, space science and physics in general. Perhaps I can help here.

 

This controversy is not an easy one to clarify. I'll give it my best shot. And I will attempt to do it without examples or thought experiments.

 

1: "That relative perception actually makes objects move closer or further apart is a logical absurdity." This is a TRUE statement. (unless I've had a bit too much Irish whiskey, and then all bets are off) ;)

 

2: "is there an objective cosmos independent of relative perception of it?" The answer is YES. Rest assured, the "truth" is indeed "out there" whether we understand it or not. ;) But this brings us to the edge of a difficulty:

 

3: Is subjectivity the same as relativity? And the answer is NO. There is a distinct difference, though I can see how they would be confused, if indeed confused they are.

 

3-A: Can we agree on the definition of "subjectivity" as the sum total of our subjective sensory perceptions and our interpretations of those perceptions based upon what we may call "common sense"? IMHO, this is a good definition. I await your opinion.

 

3-B: The definition of "relativity" is a little more arcane because it is based upon Geometry. It says that what we subjectively perceive can be influenced by two things--(1) the object or event we are perceiving may be moving relative to us. (2) the medium by which we observe (photons, waves, particles, etc) is itself traveling at a finite speed, and therefore every event we observe is actually an event that occured in our "past".

 

4: Can our perception of the Cosmos (3-A) be relied upon as representing the true state of the Cosmos? And here the answer is NO.

 

Why not? Because of #3-B. We can only perceive objects and events that provide (in any of a number of ways) a stream of information-carrying waves or particles or photons etc. And they do not travel instantaneously. Furthermore, large relative velocities between us and those objects or events distort our observations. (Einstein's Special Relativity gives us the math to actually calculate the distortion)

 

5: Even if we accept that, can't we at least agree on, say, the distance between two objects, or the time interval between two events? And here the answer is NO again. Well, if you and I are stationary with respect to each other, then we CAN agree. But if I'm moving at a large velocity away from you, then our observations will probably disagree.

 

6: Then who is right? Well that's a tricky one to answer. We're both right, assuming we have made our observations and measurements with accurate instruments and full integrity. This leads us to a bit of "philosophy" that you may have trouble with. What we can "know" about the real, external universe (#2 above) is absolutely limited by our observations. We can never, never have a "God's Eye View" of the Cosmos, if indeed, such a thing is even theoretically possible. (Which it isn't, but that's another topic.)

 

6-A: Have you not "seen" a vision of the Cosmos? Well, actually, no you haven't. To "see", even in its most general sense, implies that you have received sensory input of some kind. And all sensory input comes under 3-B above. What you have done, indeed, what *I* have done since my first interest in Astronomy at the age of 12, is to "picture" a vision of the Cosmos. We create a Metaphor of the Cosmos in our minds.

 

6-B: "Isn't the vision in my mind the same as #2 above?" It could be, but it probably isn't. Vastly unlikely. Almost certainly NO.

 

7: "Well, if you say that my vision of the Cosmos is NOT #2 above, then you must believe in "subjective realism", right?" Not necessarily. There is a third way out of this conundrum.

We can accept that 3-B represents the actual Geometry of the Cosmos, and gives us a math we can use to remove the "distortions" in our observations. You and I may actually observe the distance between the Earth and Sun to be quite different--we can use Special Relativity to adjust our observations and derive the actual value.

 

8: my ontological inquiry: "Do you think subjective perception creates reality?" Well, there are two answers to this one. If by "reality" you mean #2 above, then NO, of course not.

If by "reality" you mean #6-A, then YES, of course it does.

Everything we CAN know about the external reality of the Cosmos comes through the subjective perceptions of our senses. Sight, hearing, touch, smell, etc. Even if you include telescopes and satellites, those are just extensions of our senses.

 

Does this help?

[modest]

Notice your way of determining absolute distance involves the *measuring* of time,

 

Now to the crux: There are three well known spacial dimensions and "elapsed time" for any event is commonly called the fourth dimension. The elapsed time for light traveling sun to earth is 8.32 minutes or 499.2 seconds... invariably. That is 149 million kilometers on average... give or take earth's out-of-round orbit. This distance, and the distances to the other planets does not change through some mysterious force of observation moving them closer or further apart. Because of the limits of lightspeed in conveying images, the distances may appear to change but they do not... but for orbit irregularities.

 

It is shown by general relativity and it has been experimentally verified that time moves faster at higher altitude and slower at lower altitude. This is known as gravitational time dilation. While a ray of light moves from the earth to the sun a person located on the top of a mountain will experience more time than a person in a valley. They can both time how long the light takes to make the trip, but even if they use identical stopwatches, the two measures of duration will be different.

 

So, any value you give for universal and absolute space and time is choosing one such reference frame over all the other valid reference frames. It would force you to choose a spot on the mountain and say “that is where universal time can be measured—that is where time runs at the universal rate. A little further up the mountain and things experience more than the absolute and universal duration and a little bit lower on the mountain and things experience less than the absolute and universal duration." I can think of no way to choose such a frame.

 

It is nice, however, to see you say that measurements or observations of distance and time are different depending on velocity. I think this would make even more sense if you stopped thinking of space and time (or distance and duration—as you like to call them) as frame independent-quantities or as things that exists on their own in the universe. Space and time cannot exist in isolation. They (like velocity) are frame-dependent quantities that must be related to something or they loose their meaning. That is the essence of being *relative*. It is not human observation or human measurement that makes distance and duration relative. It is, rather, the fundamental nature of these things to exist only as a relationship to a frame of reference.

 

The quote below from Encyclopedia of Time also comments on this, but it is more directed at what you bring up about cosmic velocity from the big bang.

 

I agree that there is no universal answer in the above perspective. I do agree that "Velocity is only useful as a concept when it is compared to something else" (i.e., velocity relative to what?)Yes, I do follow.

However, the velocity of the Martian orbit around the sun is well known as is Earth's orbital velocity.

 

Right, Mars' velocity relative to the sun (or the sun's reference frame) is well-known. Just as well-known is the distance between the sun and the earth or the earth and mars as relative to the sun's reference frame. The point being: there is such an entity that these distances are relative to. Much like velocity, kinetic energy, electric current, or momentum, the concepts of distance and duration require a reference frame to be relative to in order to have meaning. It is for this reason that they are not absolute or universal. They depend on being compared to a velocity.

 

I have "seen" the expanding cosmos in vision my whole life. Relative to the locus of origin of this expansion, the velocity of Mars away from this locus is about the same as the velocity of our galaxy in its trajectory outward from "the Bang."

 

This is a slight misunderstanding of big bang theory. There is no particular spot in our universe away from which everything is expanding; nevertheless, what you're saying can be reworded in a way that is both consistent with standard cosmology and keeping with what you're saying. Velocity relative to the cosmic microwave background reference frame could be considered cosmic motion or cosmic velocity. This would be called "velocity relative to the hubble flow". This is not, however, *absolute* velocity and neither does this reference frame establish absolute time, which is explained here:

The question that may be raised in philosophical cosmology is whether or not this cosmic time constitutes an “absolute time” in the sense that Einstein rejected in his special theory of relativity. “Absolute time” and “relative time” may be defined in terms of the relation of simultaneity. If time is absolute, then this relation is two-termed, and is expressed by sentences of the form “x is simultaneous with y.” If time is relative, then the simultaneity relation is three-termed and is expressed by “x is simultaneous with y relative to z,” where z is the reference frame relative to which x and y are simultaneous. This suggests that the cosmic time posited by big bang cosmology is not absolute time, since the time measurements are made relative to the privileged reference frame. For example, the assertion that the age of the universe is about [13.7] billion years old is elliptical for the statement “relative to the privileged reference frame, the universe is [13.7] billion years old.”

 

Encyclopedia of time by Samuel L. Macey p.145

 

This 2-term/3-term explanation is right in line with what I tried to say in this post. I hope you spend some time and thought considering it.

 

~modest

[Pyrotex]

I've been studying and reading about Relativity for 35 years, and never did any teacher or author suggest or imply that because my "relativistic observation" of a speeding rocket indicated that the length of the rocket had shrunk (or its clock had slowed down), that this in any way meant that my observation had shrunk the rocket or slowed down its clock.

 

Quite the opposite. My teachers and books told me that length and time as experienced by the crew of the rocket never changed for them at all. What had changed was my observation. Relatavistic contraction of length and time (and increase of mass) are simply what I *measure*, what I *observe*. Those observations do not *cause* anything to happen. Indeed, the crew of the ship, or another astronomer cruising around at a different velocity, will observe something else.

 

Which frame of reference is the *right* one to measure from? Well, if it matters to you, then go ahead and pick one. Pick your own frame of reference. I won't mind. Really. ;)

[modest]

I'm not sure what you mean Pyro. Who was suggesting that the act of observation caused something, I mean, besides Michael?

 

Reunited clocks differ in elapsed time. The observation reflects the reality of the difference. Were you thinking something different?

 

~modest

[Michael Mooney]

Erasmus,

 

You misunderstand the basis of my objection to Modest's insistence that there is no such thing as actual, objective distance between objects, as he believes it varies with observation as and measurements/calculations based on relativity.

My argument is *not* with the latter variations. No question... relativity accounts for these variations very well. But variations in observational viewpoints and their different speeds/trajectories *does not* make the actual distances between objects change.

 

I last stated this specifically in reply to JMJones as follows:

 

So, as you acknowledged, the distance between sun and earth does not actually change during the observations from different perspectives/velocities in the four situations at hand here, but rather the relative perception and its measurements change with relative velocities, etc. "Relative" to the actual distance between the bodies, which remains the same, this could be called "observer error" even while trajectory calculations are vastly more accurate using the improved math tools of relativity

 

So you belabor the "word problems" and accompanying math without understanding what I just said above in acknowledgment of relativity *and* in criticism of any relativistic observational differences creating actual differences between objects.

 

You concluded with the following, totally overlooking the above:

Something is very wrong! The distances measured by the ship and the Earth do not agree.

Why is this, Michael?

This is a strawman argument in above explained context. The distance earth to moon is unaffected by point of view, velocity etc., of observers.

 

As for your:

It (math) implies physical things about the universe- the math of general coordinate invariance(subjective labels don't matter) implies that the universe is a curved, 4 dimensional manifold.

... See the essay earlier in this thread, link provided by Modest, on the ontology of non-Euclidean space, time and spacetime. (Wish I could search and link easily but am "challenged" in such things.) Pay special attention to the intrinsic vs extrinsic "curvature" paragraph.

(Will find it and share when I find time.)

Michael

[Michael Mooney]

.........................

Pyrotex:

Does this help?

Yes! Thank you. My comments below in italics.

 

1: "That relative perception actually makes objects move closer or further apart is a logical absurdity." This is a TRUE statement. (unless I've had a bit too much Irish whiskey, and then all bets are off)

Please inform modest.

 

2: "is there an objective cosmos independent of relative perception of it?" The answer is YES. Rest assured, the "truth" is indeed "out there" whether we understand it or not. But this brings us to the edge of a difficulty:

As I've said all along. ... Which Modest calls my error of absolutism, assuming what can not be verified by observation, which is all relative.

 

3: Is subjectivity the same as relativity? And the answer is NO. There is a distinct difference, though I can see how they would be confused, if indeed confused they are.

 

3-A: Can we agree on the definition of "subjectivity" as the sum total of our subjective sensory perceptions and our interpretations of those perceptions based upon what we may call "common sense"? IMHO, this is a good definition. I await your opinion.

I agree but would add transcendental perspective, that which can be "known" as in gnosis, which falls in the a-priori category of epistemology... knowing by resonant identity... hologram-wise... as the minutia is a minature of the "whole-o-gram" :) (Not all mystics are deluded!)

 

3-B: The definition of "relativity" is a little more arcane because it is based upon Geometry. It says that what we subjectively perceive can be influenced by two things--(1) the object or event we are perceiving may be moving relative to us. (2) the medium by which we observe (photons, waves, particles, etc) is itself traveling at a finite speed, and therefore every event we observe is actually an event that occured in our "past".

 

Agreed, but in context that *now* is ongoing always and simultaneously everywhere. Of course what we see now happened in the past, as per elapsed time of light conveying the images..

 

4: Can our perception of the Cosmos (3-A) be relied upon as representing the true state of the Cosmos? And here the answer is NO.

 

It depends on whether one's transcendental perspective is an actual vision of "what is" or just "picturing" what might be in ones image-ination. "No" assumes that all such "visions" are merely said imaginings. This is the classic argument between mystics like myself and scientists like you. I don't claim scientific validation for what I "see" as visions. But I reject your assumption that it is all just imagination... on the grounds that you have never had a mystic vision.

 

Why not? Because of #3-B. We can only perceive objects and events that provide (in any of a number of ways) a stream of information-carrying waves or particles or photons etc. And they do not travel instantaneously. Furthermore, large relative velocities between us and those objects or events distort our observations. (Einstein's Special Relativity gives us the math to actually calculate the distortion)

There is a body of work, however controversial, on "viewing at a distance" under experimentally controlled conditions. The latest book on the subject that I am aware of is "The Intention Experiment. (Forgot author for the moment.)

However, I agree with your last two statements. It's just not "the whole picture... which might include the omnipresence of consciousness as and instantaneous conveyor of info, transcending the physical senses. Perhaps a new frontier of science... "consciousness studies." Materialism is not necessarily the last word even tho it is the present basis of mainstream science.

 

5: Even if we accept that, can't we at least agree on, say, the distance between two objects, or the time interval between two events? And here the answer is NO again. Well, if you and I are stationary with respect to each other, then we CAN agree. But if I'm moving at a large velocity away from you, then our observations will probably disagree.

 

Of course.

 

6: Then who is right? Well that's a tricky one to answer. We're both right, assuming we have made our observations and measurements with accurate instruments and full integrity. This leads us to a bit of "philosophy" that you may have trouble with. What we can "know" about the real, external universe (#2 above) is absolutely limited by our observations. We can never, never have a "God's Eye View" of the Cosmos, if indeed, such a thing is even theoretically possible. (Which it isn't, but that's another topic.)

 

Here the absolute conviction of your materialistic bias is extremely clear. "Never, never??"All my life as a mystic I have had such a "Gods eye view of the cosmos."Your adamant insistence that it is impossible does not make it so. It just means that you believe that "it is all relative"... and all reality must be materialistically based Yet I am not presenting my transcendental vision as science. It remains mysticism... which differs from delusion. This I know as a career transpersonal psychologist.

 

6-A: Have you not "seen" a vision of the Cosmos? Well, actually, no you haven't. To "see", even in its most general sense, implies that you have received sensory input of some kind. And all sensory input comes under 3-B above. What you have done, indeed, what *I* have done since my first interest in Astronomy at the age of 12, is to "picture" a vision of the Cosmos. We create a Metaphor of the Cosmos in our minds.

 

As a psychologist, I must tell you that you can not tell me what I have seen and what I have not. "Seeing" via resonance in identity with a greater whole, tho not yet "science" per se is not pure hogwash either as most mainstream materialistic scientists would claim... and as you seem to be saying above.

 

6-B: "Isn't the vision in my mind the same as #2 above?" It could be, but it probably isn't. Vastly unlikely. Almost certainly NO.

 

Again, a true "vision" sees "what is" while imagination is certainly limited to the realm of possibilities. Your experience has clearly been limited to the latter, so you assume that limitation is universally true. Not actually very scientific... as per "open minded."

 

7: "Well, if you say that my vision of the Cosmos is NOT #2 above, then you must believe in "subjective realism", right?" Not necessarily. There is a third way out of this conundrum.

We can accept that 3-B represents the actual Geometry of the Cosmos, and gives us a math we can use to remove the "distortions" in our observations. You and I may actually observe the distance between the Earth and Sun to be quite different--we can use Special Relativity to adjust our observations and derive the actual value.

Agreed, as above.

Thanks for your time.

Michael

[watcher]

Well, Watcher, looks like you and Essay are the only ones talking to me here, so I'll try to wrap it up with both of you then maybe list the major unanswered questions I've raised in this thread (not all in this post) and then be on my way.

 

hi michael, i have some misgivings of my own as well. for example you have not addressed my comment that matter is 99.999 percent space.

 

nothingness is correct within the context that nothing has an independent existence.

or everything has no essential nature of its own. because something essential is not capable of change. but this universe is always changing. so within that context, nothingness is already implied in relativity. it is obvious when you notice that all the definitions and formulas in science are circular. nothing is not the same as absolute space. something absolute cannot change/transform neither capable of interaction.

 

Do you understand that the question, "What is spacetime, really?" is an ontological question which you have never addressed? Rather you have jumped to the common conclusion that it is "something" (rather than nothing) which has certain traits in and of itself, like curvature, expandability and density. Of course objects moving *through space* have various curved trajectories as masses pull on each other via gravity, but "curved space" not only does not explain how masses pull on each other (how gravity works) but it assumes the ontological status of "spacetime" as a malleable medium (as above) as a basic reality, begging the ontological question.

Are you with me on this. (Anyone? This is, after all the "Philosophy of Science" section of the forum.)

 

well to be clear, spacetime is actually a shortened word for spacetime interval. people just drop the interval and started calling it spacetime. just like you. so spacetime is actually a ratio of how much change in space for every change in time and vv.

 

the obvious implication is that space and time are not independent entities but related. so you cannot call space absolute and you cannot call time absolute. and you cannot call one real and the other an illusion.

another way to see it is that spacetime is a unified entity that manifest as space and time.

but what ever it is, it can also be argued that it is neither space nor time.

 

the reason that i treat spacetime as an entity (malleable or not) is because i don't think that they are fundamental. iow. they are not ontological. they are also "created" manifestation of something else.

 

Of course one can "clock" the elapsed time of objects as they move from a designated point A to a designated point B. This does not make "time" an actual entity, and certainly not a reality in itself which can speed up and slow down, tho, of course clocks and many natural events/cycles do that under various circumstances.

 

how can not it be a real entity if you admit that time is needed for motion? it is obvious that time is a hard currency in the universe. it is the medium of change and exchange rate of energy. if you call time not an actual entity or just an illusion, you might just as well call space as an illusion too. because they are related. its like two legs, remove the one and it wont stand.

 

It means that the future is not yet present and the past is not still present, so all there is is the present... ever... always... everywhere... simultaneously.

 

i think the origin of our sense of time comes from motion. also i think that the universal clock that the cosmos use is also its cyclic motion. imo, the spinning electrons in your eyes and brains are the reference points our perception is using to make sense of other motions in the universe. the universe in general are at sync also with the electron frequency since everything is made of electrons. so there is actually a universal clock that the universe follows for its orderly synchronized orchestrated functioning.

 

so yes time is a real entity as real as space. when cosmic consciousness tells you that time is an illusion, it means also that everything was. that nothing is really changing. because change is a function of time.

there are many ways to express this experience, some mystics called it the world as a dream, the modern version is that the universe is holographic.

 

it can be true that there is only emptiness.

and everything is as illusions... but mind you this is our only illusion.

a higher timeless existence is outside the scope of this thread. it cannot be expressed in words. not alone expressed in quantifiable equations. kurt godel thouhgt so.

 

Again, ontologically, space is the no-thing-ness in which all things exist and time is "clocking duration", neither of which nor both together are ontological realities.

This is about "what is real" not ways of "plotting" the motion of real things in space over time.

Michael

 

okay let me put my take this way, this "nothingness" you are talking about i will call reality. this nothingness is not space. it is spacelike but not part of the spacetime we are talking about. it is something more fundamental and whole. this whole manifested itself as both space and time.

 

if you are the infinite consciousness, how would you make your self manifest?

you quantize right? quantization is the process where something infinite can be measurable, observable and comprehensible. for me, it satisfies the adage "emptiness is form and form is emptiness". imo

[modest]

You misunderstand the basis of my objection to Modest's insistence that there is no such thing as actual, objective distance between objects

 

I have not said that there’s no such thing as *actual* or *objective* distance. I have objected to your description of *absolute* and *universal* distance and time. Absolute means no possibility of change and universal means applicable to all situations. The opposite of absolute and universal is “relative” which means subject to the comparison of something else.

 

Time, space, simultaneity, and mass are relative *not* absolute and universal.

 

The distance between the earth and moon is actual and objective to both the person on earth and the astronaut, but it is not absolute and universal because the distance is different for the two of them. The distance as determined in earth’s reference frame is no more real than the rocket’s reference frame. They both describe how the physical world actually physically exists. It is *not* the case that there is one ‘real’ distance or duration and all these other reference frames are just observing things differently because of some effect of perception. It is not as you say here:

 

This distance, and the distances to the other planets does not change through some mysterious force of observation moving them closer or further apart. Because of the limits of lightspeed in conveying images, the distances may appear to change but they do not.

Length contraction is not only observed—it affects physical phenomena. A muon goes a certain speed and lives a certain amount of time. They are made in the upper atmosphere and travel down toward earth. The muon would not be able to reach the ground before it decays—the distance is too great. But, in the muon’s reference frame the earth’s surface and upper atmosphere are moving at very near the speed of light, so the distance between them is contracted (from 10 km to 2 km). It can travel that distance before it dies and they do. You can read about it:

 

Muon Experiment in Relativity

 

If the distance wasn’t *really* less than 10 kilometers in the muon’s reference frame—if it only “appeared” shorter than it “really” is, then the muon couldn’t travel the distance and they wouldn’t reach the ground. Similar such things are evident with different particles in particle accelerators all the time.

 

Consider two people standing right in front of you. You judge these people to be the same size. One person (Alice) walks away from you twenty or thirty feet while the other person (Bob) remains by your side. Alice will now appear smaller than Bob (perspective makes it appear so) The further she walks away the smaller she appears. When she walks back to you and again is standing in front of you next to Bob she will again appear the same size as him.

 

Alice did not really get smaller. She only appeared to get smaller. I think that’s how you’re imagining relativity and relativistic effects. But, consider if you synchronize two clocks then send one of them on a trip around the united states on a super high speed train. When the clock gets back from its around-the-country trip the two clocks will no longer be synchronized. From your perspective, the one that did the traveling ticked more-slowly than your own identical clock. But it wasn’t some trick of perspective or observation that just made it appear to tick more slowly. When the clock returns it really does display less time. Unlike Alice who returned to Bob the same size as she left, the clock has returned displaying a different time as the reference clock. The relativistic effect was physically real and neither clock gets to say “I experienced the absolute, cosmic, universal, transcendent duration between events”.

 

They both experienced an "actual and objective" duration, but the duration itself (the duration between two events) is not absolute and universal. There were two durations, each relative to a reference frame.

 

~modest

[jedaisoul]

This thread addresses the ontology of what "spacetime" actually is, if indeed it is actually "something." This is a philosophical inquiry/debate.

Hi Michael,

 

You are not the only person who has doubts about whether General Relativity accurately describes the universe we live in. I regard it as a mathematical model. However, you (and I) have to recognise that it is a more accurate mathematical model than Newtonian relativity. So propounding Newtonian relativity per se (as you appear to be doing) is a lost cause.

 

What is wrong with Newtonian relativity? Well, it originated before it was known that the velocity of light is fixed and finite. And you can't just bolt a fixed and finite velocity of light on to Newtonian relativity. The sums do not add up. I can prove that is true, but that is jumping ahead...

 

So where do we go from here? Well, firstly, I'd suggest that you asked the wrong question. "What is spacetime" is not an ontological question. Spacetime is a term used to describe a particular view of space and time. That is why people have been giving you a master class in the mathematics of Special and General Relativity. But you do not "buy" all that relativity stuff, so that is a waste of time.

 

What I think you meant to ask is "What is the nature of space and time". That is an ontological question. It is not focussed on one particular interpretation, spacetime, though it is open to that interpretation. It is also open to different ontological interpretations. And there are at least two other models that have already been proposed:

 

The first is CICS (Complete and Incomplete Co-ordinate Systems). This was proposed by Steve Bryant, and is published on his web site RelativityChallenge.Com. Basically, his idea is that the results of the famous Michelson-Morley experiment have always been misinterpreted as if the experiment took place in a complete co-ordinate system. When re-interpreted as being an incomplete co-ordinate system, the need to apply the Lorentz transformation (the basis of Einsteinian relativity) evaporates.

 

The second is Simultaneity-Time. This is proposed by me on my web site Simultaneity-Time. This is based on the observation that when you apply a velocity of light that is fixed and finite with respect to the target to an otherwise Newtonian model, you derive a "velocity of light" effect. (Hence why I said above that the numbers don't add up if you try to just bolt a fixed and finite velocity of light on to Newtonian relativity). This "velocity of light" effect is mathematically, and conceptually, different from the Lorentz transformation, and hence leads to a distinctly different model of the universe.

 

So whether any, or none, of these models really reflect reality, the point I'm trying to make is that whatever model you wish to propose, it has to stand up mathematically.

[Michael Mooney]

Watcher:

hi michael, i have some misgivings of my own as well. for example you have not addressed my comment that matter is 99.999 percent space.

 

Hi Watcher,

Playing catch-up here, and hope to have time to address other replies too.... so I'll address the highlights of what I see as miscommunication between us.

I define space as the no-thing-ness between things, on all scales... micro ( subatomic and "between atom" space... be it whatever percentage) to macro (the emptiness between mass bodies of all kinds on cosmic scale.)

nothingness is correct within the context that nothing has an independent existence.

or everything has no essential nature of its own. because something essential is not capable of change. but this universe is always changing. so within that context, nothingness is already implied in relativity. it is obvious when you notice that all the definitions and formulas in science are circular. nothing is not the same as absolute space. something absolute cannot change/transform neither capable of interaction.

This sounds very confused to me. I equate space=nothingness, as above. "Things" of whatever ontological nature exist *in space* and all movement is movement of "things" (in the broadest sense including light and the four forces) *through space.* Though I agree that relativity has developed way more sophisticated and accurate math than Newtonian physics, I challenge the claim, obviously, that space "itself" curves, expands, contracts, etc., as relativity claims, based on a non-Euclidean model of spacial geometry... which I have already critiqued extensively in this thread. (It starts with the shortest distance between two points being a line through "curved space" rather than a straight line.

No one in this forum has yet replied to the challenge as to how the shortest distance between two points is *not a straight line.* Then, Non-Euclidean "space" goes into how parallel lines converge or diverge aa projected through this "curved space."

Of course, if space is no-thing, there is no "it" to curve, tho, of course things traveling through space have curved trajectories as masses pull mutually on each other (and on light.)

 

Maybe one more example of miscommunication will suffice. You wrote:

well to be clear, spacetime is actually a shortened word for spacetime interval. people just drop the interval and started calling it spacetime. just like you. so spacetime is actually a ratio of how much change in space for every change in time and vv.

 

the obvious implication is that space and time are not independent entities but related. so you cannot call space absolute and you cannot call time absolute. and you cannot call one real and the other an illusion.

another way to see it is that spacetime is a unified entity that manifest as space and time.

 

Clearly velocity of masses and light is stated in terms of distance traveled per unit of time. Distance is is not a "thing." It is one of 3 spacial dimensions, the "line" between designated "points." (The other two are area and volume, tho neither requires a limit... i.e., space can be described as various geometric shapes or refer to infinite emptiness. Any "end of space" in the universal sense is an ill-conceived notion... obviously.

Time is not a thing either. It is clearly "event duration" as the "event" is designated by the observer "clocking" it. All the motion in the cosmos would continue as is without anyone around with a clock picking a specific focus... an earth revolution or orbit, or a tiny fraction of it... or the estimate elapsed time since the "big bang." The events happen "all by themselves." They don't require clocks timing them to "happen."

I think this is sufficient clarification of what I am presenting about "spacetime" (and the error of its reification) in this thread.

 

Well... Ive used up my "time" for this session "on the grid" without getting to the other posted replies. Back asap to do so.

Hopefully the above has already addressed such statements later in your post such as:

how can not it be a real entity if you admit that time is needed for motion? it is obvious that time is a hard currency in the universe.

As above. Cosmos has a dynamic life of its own whether any life-forms anywhere are "clocking" parts of it or not!

Michael