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Are My Doubts On Metric Space Expansion Valid

Iredia
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1/28/2014 9:41:44 PM
Posted: 2 years ago
I ask because to me the logic is simple. Space is nothing. Nothing doesn't expand, only matter does. Therefore, to say space expands is an absurdity. Here is the little I know on the issue (gleaned from various sources).

The Doppler effect is the principle used in reading spectral lines from stars to compute their velocities.

Einstein's theory of relativity requires the speed of light to be the highest possible speed limit whilst also being a constant.

Stars are seen to possess speeds which surpass light and this creates a quandary between Einstein's theory and the theory of relativity. To escape this space is said to expand whilst stars don't move.

This I think is false because there are only two ways expansion can occur.

* Objects (or molecules in an object) move away from each other through space.
* Objects are SAID to expand whilst remaining motionless

It's clear to me scientists take the second way (which is clearly absurd) but conceal it by shunting the problem to space.

I particularly would like relevant scientists or any one who agrees with space expansion to critique this.

Thanks.
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Sidewalker
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1/29/2014 10:34:03 AM
Posted: 2 years ago
At 1/28/2014 9:41:44 PM, Iredia wrote:
I ask because to me the logic is simple. Space is nothing. Nothing doesn't expand, only matter does. Therefore, to say space expands is an absurdity.

It isn"t space that is said to be expanding; it is the space-time of relativity theory that is expanding. Within the theoretical framework of General Relativity space isn"t nothing; it is something that can be curved, it can expand, contract, etc., so the question becomes, within the theoretical framework of GR, how can the expansion of space be understood?

Here"s how: Within the conceptual framework of GR, space is a manifold defined by a coordinate system within which objects can be located, just like what you learned in Geometry class about Euclidean space which was independent of time. But space isn"t an independent entity within the mathematical framework of GR; space and time are combined into coordinate system that has four dimensions, three of space and one of time. It is counterintuitive to what we learned in Geometry class, but within GR, the three coordinates of space and one of time are combined into a single geometry. Within the intuitive framework of Euclidean Geometry, time is invariant, it isn"t in the coordinate system, so it is indeed absurd to say space is expanding because space itself cannot expand as that would require movement, which would require time, and time isn"t a coordinate in Euclidean geometry. But In a four dimensional coordinate system, space is a metric within the coordinate system, and in that coordinate system the metric expands with the passage of time, which is why it is referred to as the metric expansion of space, it"s the metric that expands within the conceptual framework of GR. GR doesn"t use Euclidean space, it uses Minkowski space, and by including time in the geometric coordinate system, space becomes a hypersurface within a space-time geometry, which is why it can be curved, and that conceptual hypersurface within the space-time coordinate system is what is expanding.

That only clears up the confusion if you recognize that it is referential to a mathematical formula, and mathematics is an abstraction, we still have no idea why the abstraction of mathematics has such an "Unreasonable Effectiveness in the Natural Sciences" (Eugene Wigner), It does, and we don"t know why, but we can"t confuse the abstraction of mathematics with reality, they are in fact two different things. This "Unreasonable Effectiveness" is born out in the fact that there are plenty of observations that do indicate that the metric expansion of space is descriptive (and prescriptive) of reality, which is to say that this particular mathematical conceptual framework works, it corresponds with the observational data so it has conceptual value as a descriptive scientific theory.

Recognize that science is descriptive rather than explanatory, these formulas don't necessarily explain reality, they are considered correct if they describe reality.

Here is the little I know on the issue (gleaned from various sources).

The Doppler effect is the principle used in reading spectral lines from stars to compute their velocities.

Yes, the observed Hubble red shift is Doppler in nature and so it can be interpreted as an indication that the galaxies are moving away from us. The question becomes, are they moving through space or is it space that is expanding.

Einstein's theory of relativity requires the speed of light to be the highest possible speed limit whilst also being a constant.

All of the observations demonstrated that the speed of light was constant no matter how the observer was moving, so Einstein considered it to be a principle of nature and proceeded to work out the implications mathematically to develop the Special Theory of Relativity. I"d say it"s more accurate to say it "assumes it" to be a fact of nature rather than "requires it".

Stars are seen to possess speeds which surpass light and this creates a quandary between Einstein's theory and the theory of relativity. To escape this space is said to expand whilst stars don't move.

It certainly was a quandary when Georges Lema"tre initially presented his findings to Einstein, Einstein was completely discombobulated by it for a couple decades, but it"s also interesting to note that he was applying reasonable values to Einstein"s GR Equations, but the analysis was one that didn"t include matter in the calculations. What he showed Einstein was that space should be expanding within his conceptual framework independently of the existence of matter. The "upper speed limit" of Special Relativity doesn"t apply to the metric expansion of space itself, it only applies to an object moving through space, so the "upper limit" isn"t violated within the conceptual framework of the theory of Special Relativity and the calculations that indicated it should be expanding had nothing to do with the matter side of the equations.

This I think is false because there are only two ways expansion can occur.

* Objects (or molecules in an object) move away from each other through space.
* Objects are SAID to expand whilst remaining motionless

It all comes down to how you choose to measure distance and time and the conceptual framework within which you define "expansion". We know that Relativity Theory accommodates different observations from different reference frames, so recognizing the hypersurface characteristic of space in the GT space-time geometry, here is a good way to think of it. Imagine three dots in a row on a balloon one inch apart, if you inflate the balloon so that the surface area doubles in one minute, the dots are now two inches apart. From the frame of reference of the middle dot, each of the two dots moved an inch away during that minute, but the first dot saw the second dot move one inch a minute and the third dot move away at two inches a minute, the third dot appears to be moving twice as fast as the second from the first dot"s frame of reference, but at the same speed from the middle dot frame of reference. That is comparable to what we observe with red shift, the farther away galaxies are, the faster they appear to be moving away from us. This is seen as confirmation that it"s the space that is actually expanding in accordance with the predictions of General Relativity.

It's clear to me scientists take the second way (which is clearly absurd) but conceal it by shunting the problem to space.

No, it"s only absurd when you apply the intuitive Euclidean conception of space to it, it actually makes sense in a four dimensional framework, the appearance of "shunting" problem comes from looking at space in the space-time framework as if it is a time independent variable. It"s counterintuitive because we intuit a Euclidean Space in a framework of absolute Newtonian time.

I particularly would like relevant scientists or any one who agrees with space expansion to critique this.

It"s a subject matter that interests me but I don"t think that makes me a "relevant scientist", but I do agree with "space expansion" within the conceptual framework of General Relativity in the sense that it works and it agrees with our observations, which is what a valid theory is supposed to do. So I took a stab at it, I hope this does something to help explain it.

Thanks.
"It is one of the commonest of mistakes to consider that the limit of our power of perception is also the limit of all there is to perceive." " C. W. Leadbeater
Iredia
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1/29/2014 12:25:43 PM
Posted: 2 years ago
@ Sidewalker

Not convinced. I fear that going all the way into technicalities will obscure the issue. However, lemme state upfront that I have no problems with four-dimensional space time. In fact it's intuitive for me because I think it's obvious upon a little thinking that time (in the sense of events) apply differently to different regions in space. It's night somewhere in India, it's likely noon in your place. So simply occupying different spaces puts objects in a different time-frame.

That said, you lost me when you talked of space becoming a something that can curve expand, contract etc I can only understand that in a metaphorical sense not in a real sense because I understand space to be Newtonian in real terms. Put simply, space exists without reference to anything else_BTW it is nothing. If as a space it deals with the distribution of galaxies in space then it would be more feasible because that is easy to conceptualize. If metric expansion was a model to work with the data eg ideal gases, Bohr's atomic model I would think it more reasonable. But suggesting Milownski space within GR ACTUALLY allows space to expand is my problem. We may need to address how I understand space and time.

Finally, it's clear that the expansion of this metric (which happens to be the FLWR metric) underscores my point. The expansion of space is conceptual not actual. Thanks for the response.
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Enji
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1/29/2014 3:11:38 PM
Posted: 2 years ago
At 1/28/2014 9:41:44 PM, Iredia wrote:
I ask because to me the logic is simple. Space is nothing. Nothing doesn't expand, only matter does. Therefore, to say space expands is an absurdity.

The underlined is an assumption rather than logic -- the logic may be valid but the conclusion incorrect if the underlined is untrue. The relevant question, then, is "What is space(time) and how can we know?"

As to the "how can we know part," I think it should be self evident that we can't determine the nature of space through a priori reasoning as you do here -- a posteriori reasoning is necessary.
Enji
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1/29/2014 3:11:53 PM
Posted: 2 years ago
At 1/29/2014 3:11:38 PM, Enji wrote:
At 1/28/2014 9:41:44 PM, Iredia wrote:
I ask because to me the logic is simple. Space is nothing. Nothing doesn't expand, only matter does. Therefore, to say space expands is an absurdity.

The underlined is an assumption rather than logic -- the logic may be valid but the conclusion incorrect if the underlined is untrue. The relevant question, then, is "What is space(time) and how can we know?"

As to the "how can we know part," I think it should be self evident that we can't determine the nature of space through a priori reasoning as you do here -- a posteriori reasoning is necessary.

oops didn't mean to add this yet :(
Iredia
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1/29/2014 7:51:43 PM
Posted: 2 years ago
At 1/29/2014 3:11:38 PM, Enji wrote:

The underlined is an assumption rather than logic -- the logic may be valid but the conclusion incorrect if the underlined is untrue. The relevant question, then, is "What is space(time) and how can we know?"

Logic always involve assumptions. And the underlined is not untrue. As for your question I fear it has a snag: 'what' or 'how' don't apply to space as I've described. Spacetime while an objective part of reality involves a flaw. For example, when Krauss states in 'A Universe From Nothing' that space is nothing and is still something I agree even though it's obviously contradictory.


As to the "how can we know part," I think it should be self evident that we can't determine the nature of space through a priori reasoning as you do here -- a posteriori reasoning is necessary.

What makes you think so ? I happen to think otherwise. It is only aprioriwise space can be understood. The same way infinity is. Clearly no one has experienced infinity because we are finite beings; but we routinely assume and work with the concept a priori. Same with space. We live in a world that is 'something' and humans are part of that 'something'. You can not, therefore, experience nothing or observe that 'everything exists in space (or nothing)'. All you can do is assume so by by means of inference from matter existing in another material medium. Remove the material medium and what do we have ? Nothing. The 'thing' all matter exists in.

I think a posteriori reason necessarily applies to metrics of space (km, m, parsecs etc) but even then a priori reasoning is necessary to the formulation of these metrics. In fact, it may be that's where my disagreements lie.
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Sidewalker
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1/29/2014 8:14:23 PM
Posted: 2 years ago
At 1/29/2014 12:25:43 PM, Iredia wrote:
@ Sidewalker

Not convinced. I fear that going all the way into technicalities will obscure the issue. However, lemme state upfront that I have no problems with four-dimensional space time. In fact it's intuitive for me because I think it's obvious upon a little thinking that time (in the sense of events) apply differently to different regions in space. It's night somewhere in India, it's likely noon in your place. So simply occupying different spaces puts objects in a different time-frame.

That said, you lost me when you talked of space becoming a something that can curve expand, contract etc I can only understand that in a metaphorical sense not in a real sense because I understand space to be Newtonian in real terms. Put simply, space exists without reference to anything else_BTW it is nothing. If as a space it deals with the distribution of galaxies in space then it would be more feasible because that is easy to conceptualize. If metric expansion was a model to work with the data eg ideal gases, Bohr's atomic model I would think it more reasonable. But suggesting Milownski space within GR ACTUALLY allows space to expand is my problem. We may need to address how I understand space and time.

Finally, it's clear that the expansion of this metric (which happens to be the FLWR metric) underscores my point. The expansion of space is conceptual not actual. Thanks for the response.

How do you reconcile your rejection of the metric expansion of space with the corroborating observations?

The Hubble Redshift, time dilation in type 1A Supernovae, cooling measurements of the CMBR, and other observations taken together make most cosmologists consider the metric expansion of space to be an observed feature of the universe. The expansion provides an explanatory framework for a wide range of cosmological observations, how do you account for these phenomena without it?
"It is one of the commonest of mistakes to consider that the limit of our power of perception is also the limit of all there is to perceive." " C. W. Leadbeater
Juan_Pablo
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1/29/2014 8:17:10 PM
Posted: 2 years ago
At 1/29/2014 7:51:43 PM, Iredia wrote:
At 1/29/2014 3:11:38 PM, Enji wrote:

The underlined is an assumption rather than logic -- the logic may be valid but the conclusion incorrect if the underlined is untrue. The relevant question, then, is "What is space(time) and how can we know?"

Logic always involve assumptions. And the underlined is not untrue. As for your question I fear it has a snag: 'what' or 'how' don't apply to space as I've described. Spacetime while an objective part of reality involves a flaw. For example, when Krauss states in 'A Universe From Nothing' that space is nothing and is still something I agree even though it's obviously contradictory.


As to the "how can we know part," I think it should be self evident that we can't determine the nature of space through a priori reasoning as you do here -- a posteriori reasoning is necessary.

What makes you think so ? I happen to think otherwise. It is only aprioriwise space can be understood. The same way infinity is. Clearly no one has experienced infinity because we are finite beings; but we routinely assume and work with the concept a priori. Same with space. We live in a world that is 'something' and humans are part of that 'something'. You can not, therefore, experience nothing or observe that 'everything exists in space (or nothing)'. All you can do is assume so by by means of inference from matter existing in another material medium. Remove the material medium and what do we have ? Nothing. The 'thing' all matter exists in.

I think a posteriori reason necessarily applies to metrics of space (km, m, parsecs etc) but even then a priori reasoning is necessary to the formulation of these metrics. In fact, it may be that's where my disagreements lie.

Iredia, actually you experience forms of infinity everything. This premise has already been established in both number theory and set theory.

For example: take an ordinary 12 inch ruler and you'll see it divided into increments of inches. But you can also take each inch and divide it into many more increments. Both theories show that you can divided each inch increment into an infinite number of fractions.

Another way to think of this is to say there are an infinite number of rational numbers and points between 0 inches and 1 inch as demarcated on the ruler. ( A rational number is a fraction. )

So you're actually already playing with infinities when you deal with any quantity in the universe. Infinity is an inescapable detail.

What's startling about this is that infinities can be compared! Take the infinite number of numerical points between 0 and 1 inch on the ruler and 2 inches to 4 inches on the same ruler and you will find that second infinite number of points is larger than the first!
Iredia
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1/29/2014 8:40:54 PM
Posted: 2 years ago
At 1/29/2014 8:14:23 PM, Sidewalker wrote:

How do you reconcile your rejection of the metric expansion of space with the corroborating observations?

The Hubble Redshift, time dilation in type 1A Supernovae, cooling measurements of the CMBR, and other observations taken together make most cosmologists consider the metric expansion of space to be an observed feature of the universe. The expansion provides an explanatory framework for a wide range of cosmological observations, how do you account for these phenomena without it?

I actually think they are moving THROUGH space and apparently it brings a quandary between spectral readings and Einstein's GR (the speed of light as a constant). This is why I suggested we might need to address my understanding of space or better yet you may explain how science views space as.
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Skepticalone
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1/29/2014 9:55:47 PM
Posted: 2 years ago
At 1/29/2014 8:40:54 PM, Iredia wrote:
At 1/29/2014 8:14:23 PM, Sidewalker wrote:

How do you reconcile your rejection of the metric expansion of space with the corroborating observations?

The Hubble Redshift, time dilation in type 1A Supernovae, cooling measurements of the CMBR, and other observations taken together make most cosmologists consider the metric expansion of space to be an observed feature of the universe. The expansion provides an explanatory framework for a wide range of cosmological observations, how do you account for these phenomena without it?

I actually think they are moving THROUGH space and apparently it brings a quandary between spectral readings and Einstein's GR (the speed of light as a constant). This is why I suggested we might need to address my understanding of space or better yet you may explain how science views space as.

I like the analogy of a balloon with dots drawn on it. When the balloon (space) is blown up, the dots (stars) move apart without changing location on the surface of the balloon. As I understand it, it is possible for space to exceed the speed of light. The speed of light is a maximum speed through the medium of space, but space is not restricted by this "speed limit". Anyone feel free to correct me, if I have made an error.
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Sidewalker
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1/30/2014 6:07:58 AM
Posted: 2 years ago
At 1/29/2014 8:40:54 PM, Iredia wrote:
At 1/29/2014 8:14:23 PM, Sidewalker wrote:

How do you reconcile your rejection of the metric expansion of space with the corroborating observations?

The Hubble Redshift, time dilation in type 1A Supernovae, cooling measurements of the CMBR, and other observations taken together make most cosmologists consider the metric expansion of space to be an observed feature of the universe. The expansion provides an explanatory framework for a wide range of cosmological observations, how do you account for these phenomena without it?

I actually think they are moving THROUGH space and apparently it brings a quandary between spectral readings and Einstein's GR (the speed of light as a constant). This is why I suggested we might need to address my understanding of space or better yet you may explain how science views space as.

If that is the case, then the observations are that everything is moving away from the earth and the farther away it is, the faster it is moving. How do you account for that?
"It is one of the commonest of mistakes to consider that the limit of our power of perception is also the limit of all there is to perceive." " C. W. Leadbeater
Iredia
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1/30/2014 6:22:35 AM
Posted: 2 years ago
At 1/30/2014 6:07:58 AM, Sidewalker wrote:
At 1/29/2014 8:40:54 PM, Iredia wrote:
At 1/29/2014 8:14:23 PM, Sidewalker wrote:

How do you reconcile your rejection of the metric expansion of space with the corroborating observations?

The Hubble Redshift, time dilation in type 1A Supernovae, cooling measurements of the CMBR, and other observations taken together make most cosmologists consider the metric expansion of space to be an observed feature of the universe. The expansion provides an explanatory framework for a wide range of cosmological observations, how do you account for these phenomena without it?

I actually think they are moving THROUGH space and apparently it brings a quandary between spectral readings and Einstein's GR (the speed of light as a constant). This is why I suggested we might need to address my understanding of space or better yet you may explain how science views space as.

If that is the case, then the observations are that everything is moving away from the earth and the farther away it is, the faster it is moving. How do you account for that?

A force would be responsible for that. In any case, if you know how metric expansion of space explains things say it. As simple as possible, this time.
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Sidewalker
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1/30/2014 6:53:28 AM
Posted: 2 years ago
At 1/30/2014 6:22:35 AM, Iredia wrote:
At 1/30/2014 6:07:58 AM, Sidewalker wrote:
At 1/29/2014 8:40:54 PM, Iredia wrote:
At 1/29/2014 8:14:23 PM, Sidewalker wrote:

How do you reconcile your rejection of the metric expansion of space with the corroborating observations?

The Hubble Redshift, time dilation in type 1A Supernovae, cooling measurements of the CMBR, and other observations taken together make most cosmologists consider the metric expansion of space to be an observed feature of the universe. The expansion provides an explanatory framework for a wide range of cosmological observations, how do you account for these phenomena without it?

I actually think they are moving THROUGH space and apparently it brings a quandary between spectral readings and Einstein's GR (the speed of light as a constant). This is why I suggested we might need to address my understanding of space or better yet you may explain how science views space as.

If that is the case, then the observations are that everything is moving away from the earth and the farther away it is, the faster it is moving. How do you account for that?

A force would be responsible for that.

For instance?

In any case, if you know how metric expansion of space explains things say it. As simple as possible, this time.

Science is descriptive rather than explanatory, and the metric expansion of space describes the observations better than any competing theory at the moment, and hence, it is a valid scientific theory. If you have another theory that better describes the observations, that might serve to refute it, but "I'm not convinced" just doesn't do it.

GR is just a descriptive mathematical model, what makes it valid is the fact that it fits the observations both predictively and retrodictively. In science, if it works, it's valid, that's all there is to it.
"It is one of the commonest of mistakes to consider that the limit of our power of perception is also the limit of all there is to perceive." " C. W. Leadbeater
chui
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1/30/2014 8:06:15 AM
Posted: 2 years ago
At 1/29/2014 8:40:54 PM, Iredia wrote:
At 1/29/2014 8:14:23 PM, Sidewalker wrote:


I actually think they are moving THROUGH space and apparently it brings a quandary between spectral readings and Einstein's GR (the speed of light as a constant). This is why I suggested we might need to address my understanding of space or better yet you may explain how science views space as.

If galaxies move through space, how do you reconcile this with the established fact that the velocity of a galaxy is proportional to distance for all galaxies (except for the few close galaxies). What gave the galaxies their energy and kept them all moving in a non random fashion? If galaxies move through space I would expect their motion to be more like the random motion of gas atoms.
Iredia
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1/30/2014 7:25:47 PM
Posted: 2 years ago
At 1/30/2014 6:53:28 AM, Sidewalker wrote:

For instance?


I would be speculating saying that. But movement of any kind is due to a force.

Science is descriptive rather than explanatory, and the metric expansion of space describes the observations better than any competing theory at the moment, and hence, it is a valid scientific theory. If you have another theory that better describes the observations, that might serve to refute it, but "I'm not convinced" just doesn't do it.

Explanations are a way of describing.


GR is just a descriptive mathematical model, what makes it valid is the fact that it fits the observations both predictively and retrodictively. In science, if it works, it's valid, that's all there is to it.

I was expecting a simple explanation on how the math model explains the data and how it justifies the statement that space expands. That said, my stance has been very simple so anyone will grasp what I mean.

"Space is nothing. Nothing doesn't expand, only matter does. Therefore, to say space expands is an absurdity."

Then you say under space-time in GR can expand etc. which muddles things up. But we may be able to stop things from going further downhill so why what do you say to answer the following question after I examine your earlier analogy of the baloon.

I think the baloon demonstrates the flaw I talk of. Space is nothing so making an analogy to a baloon wouldn't apply to it. But let's pretend the ballon is space and there are dots on it representing stars. The baloon expand and the stars move with the baloon but relative to the baloon's surface they aren't moving. But actually, space exists irrespective of both and both the baloon and the stars on it move relative to space they are in. This analogy will only make sense if there is an actual material medium stars are tacked on to which is expanding but there is none. To therefore say space (they are in) is expanding fails since space isn't matter, and will need space to expand into.

Now the question:

Does spacetime actually (ie in real, observable terms) expand ?
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Iredia
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1/30/2014 7:35:18 PM
Posted: 2 years ago
At 1/30/2014 8:06:15 AM, chui wrote:

If galaxies move through space, how do you reconcile this with the established fact that the velocity of a galaxy is proportional to distance for all galaxies (except for the few close galaxies). What gave the galaxies their energy and kept them all moving in a non random fashion? If galaxies move through space I would expect their motion to be more like the random motion of gas atoms.

I think this a rhetorical question. In any case, galaxies moving through space hardly contradicts the velocities observed: it does however contradict what GR prescribes the galaxies velocities musn't exceed (lightspeed). Dark energy_it seems_has been proposed as what is responsible for galaxies moving the way they do and gravity operates differently in outer space (eg weightlessness and differences in fire appearance) so you shouldn't expect galaxies to move a la Brownian motion.
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JohnPaul
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1/30/2014 10:10:12 PM
Posted: 2 years ago
At 1/30/2014 7:35:18 PM, Iredia wrote:
At 1/30/2014 8:06:15 AM, chui wrote:

If galaxies move through space, how do you reconcile this with the established fact that the velocity of a galaxy is proportional to distance for all galaxies (except for the few close galaxies). What gave the galaxies their energy and kept them all moving in a non random fashion? If galaxies move through space I would expect their motion to be more like the random motion of gas atoms.

I think this a rhetorical question. In any case, galaxies moving through space hardly contradicts the velocities observed: it does however contradict what GR prescribes the galaxies velocities musn't exceed (lightspeed). Dark energy_it seems_has been proposed as what is responsible for galaxies moving the way they do and gravity operates differently in outer space (eg weightlessness and differences in fire appearance) so you shouldn't expect galaxies to move a la Brownian motion.

What do you mean by "gravity operates differently in outer space"?
chui
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1/31/2014 6:14:08 AM
Posted: 2 years ago
At 1/30/2014 7:35:18 PM, Iredia wrote:
At 1/30/2014 8:06:15 AM, chui wrote:

If galaxies move through space, how do you reconcile this with the established fact that the velocity of a galaxy is proportional to distance for all galaxies (except for the few close galaxies). What gave the galaxies their energy and kept them all moving in a non random fashion? If galaxies move through space I would expect their motion to be more like the random motion of gas atoms.

I think this a rhetorical question. In any case, galaxies moving through space hardly contradicts the velocities observed: it does however contradict what GR prescribes the galaxies velocities musn't exceed (lightspeed). Dark energy_it seems_has been proposed as what is responsible for galaxies moving the way they do and gravity operates differently in outer space (eg weightlessness and differences in fire appearance) so you shouldn't expect galaxies to move a la Brownian motion.

I was not being rhetorical. I am asking why should the velocity of galaxies fit neatly to a pattern? This suggest a common cause for the velocity of all galaxies. What makes galaxies move through space the way they do and not in a random motion? Dark energy was proposed to explain why expansion is gradually speeding up not slowing down, but it was not needed to explain expansion in itself. You are questioning expansion, so I feel need to answer my question without reference to expansion mechanisms.

What is the evidence of galaxies exceeding light speed? There is no maximum limit to Doppler red shift in relativity. A large red shift does not require a velocity beyond light speed. I wonder if you are thinking of classical Doppler shift not relativistic Doppler.
Sidewalker
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1/31/2014 6:29:13 AM
Posted: 2 years ago
At 1/30/2014 7:25:47 PM, Iredia wrote:
At 1/30/2014 6:53:28 AM, Sidewalker wrote:

For instance?

I would be speculating saying that. But movement of any kind is due to a force.

OK, and as long as we are speculating, the metric expansion of space is due to a force, problem solved, easy peasy.

Science is descriptive rather than explanatory, and the metric expansion of space describes the observations better than any competing theory at the moment, and hence, it is a valid scientific theory. If you have another theory that better describes the observations, that might serve to refute it, but "I'm not convinced" just doesn't do it.

Explanations are a way of describing.

To say "Space is nothing. Nothing doesn't expand, only matter does" doesn"t explain or describe. Therefore, to just say "Space is nothing" is an absurdity.

GR is just a descriptive mathematical model, what makes it valid is the fact that it fits the observations both predictively and retrodictively. In science, if it works, it's valid, that's all there is to it.

I was expecting a simple explanation on how the math model explains the data and how it justifies the statement that space expands. That said, my stance has been very simple so anyone will grasp what I mean.

I already gave you a simple explanation of how the math model explains the data, it works, it correlates the observations better than any competing theory, it is an observed fact. GR is one of the most tested and confirmed theories of all time, it predicted a metric expansion of space and all of the subsequent observations confirmed that prediction.

"Space is nothing. Nothing doesn't expand, only matter does. Therefore, to say space expands is an absurdity."

If "Space is nothing", then it can have no properties, to say "Nothing doesn't expand" is to attribute a property to nothing, and that is what is an absurdity.

Then you say under space-time in GR can expand etc. which muddles things up. But we may be able to stop things from going further downhill so why what do you say to answer the following question after I examine your earlier analogy of the baloon.

If you say space is nothing BUT the total of spatial relations between objects, then we observe that the spatial relations between distant objects in the Universe are expanding in accordance with the prediction of the theory of General Relativity. If in fact, space is nothing, then the positions and other properties of objects are only meaningful relative to other objects, and their relative movement is only meaningful relative to the passage of time. If you mathematically model these relations between objects, and between these objects and time, guess what? You get a four dimensional space-time model that corresponds to observations, and it predicts that the spatial relationships should expand over time, and then if you take a look to see if that is the case, you find that the observations confirm the prediction.

I think the baloon demonstrates the flaw I talk of. Space is nothing so making an analogy to a baloon wouldn't apply to it. But let's pretend the ballon is space and there are dots on it representing stars. The baloon expand and the stars move with the baloon but relative to the baloon's surface they aren't moving. But actually, space exists irrespective of both and both the baloon and the stars on it move relative to space they are in. This analogy will only make sense if there is an actual material medium stars are tacked on to which is expanding but there is none. To therefore say space (they are in) is expanding fails since space isn't matter, and will need space to expand into.

Nope, you just don't understand what an analogy is.

Now the question:

Does spacetime actually (ie in real, observable terms) expand ?

I already answered that question, all of the associated observations corroborate the prediction that space-time is actually expanding, (ie. in real, observable terms).
"It is one of the commonest of mistakes to consider that the limit of our power of perception is also the limit of all there is to perceive." " C. W. Leadbeater
Sidewalker
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1/31/2014 6:36:37 AM
Posted: 2 years ago
At 1/30/2014 7:35:18 PM, Iredia wrote:
At 1/30/2014 8:06:15 AM, chui wrote:

If galaxies move through space, how do you reconcile this with the established fact that the velocity of a galaxy is proportional to distance for all galaxies (except for the few close galaxies). What gave the galaxies their energy and kept them all moving in a non random fashion? If galaxies move through space I would expect their motion to be more like the random motion of gas atoms.

I think this a rhetorical question. In any case, galaxies moving through space hardly contradicts the velocities observed: it does however contradict what GR prescribes the galaxies velocities musn't exceed (lightspeed).

Well yeah, except that isn't what GR says.

Dark energy_it seems_has been proposed as what is responsible for galaxies moving the way they do

Nope, Dark Energy has been postulated as what is responsible for the fact that the galaxy movement is accelerating.

and gravity operates differently in outer space (eg weightlessness and differences in fire appearance)

No it doesn't.

so you shouldn't expect galaxies to move a la Brownian motion.

You shouldn't expect them to all be moving away from us, and you certainly wouldn't expect the speed at which they are moving away to be greater with distance. That would indicate a metric expansion of space.
"It is one of the commonest of mistakes to consider that the limit of our power of perception is also the limit of all there is to perceive." " C. W. Leadbeater
Iredia
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1/31/2014 8:38:19 AM
Posted: 2 years ago
At 1/30/2014 10:10:12 PM, JohnPaul wrote:
At 1/30/2014 7:35:18 PM, Iredia wrote:
At 1/30/2014 8:06:15 AM, chui wrote:

If galaxies move through space, how do you reconcile this with the established fact that the velocity of a galaxy is proportional to distance for all galaxies (except for the few close galaxies). What gave the galaxies their energy and kept them all moving in a non random fashion? If galaxies move through space I would expect their motion to be more like the random motion of gas atoms.

I think this a rhetorical question. In any case, galaxies moving through space hardly contradicts the velocities observed: it does however contradict what GR prescribes the galaxies velocities musn't exceed (lightspeed). Dark energy_it seems_has been proposed as what is responsible for galaxies moving the way they do and gravity operates differently in outer space (eg weightlessness and differences in fire appearance) so you shouldn't expect galaxies to move a la Brownian motion.

What do you mean by "gravity operates differently in outer space"?

The effect of gravity on matter is different. For example, gravity is lesser in outer space so you feel weightless. Air can't be set up BY GRAVITY in convection currents so fires are different (concentric not wavy). Of course, it still remains an attractive force.
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Iredia
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1/31/2014 9:27:12 AM
Posted: 2 years ago
At 1/31/2014 6:29:13 AM, Sidewalker wrote:

OK, and as long as we are speculating, the metric expansion of space is due to a force, problem solved, easy peasy.

OK.



To say "Space is nothing. Nothing doesn't expand, only matter does" doesn"t explain or describe. Therefore, to just say "Space is nothing" is an absurdity.

Do you think infinity is an absurdity too ? Because the concept explains nothing. BTW, space being nothing is meant to be an axiom. However, we see that matter exists in something (this is apparent seeing Earth in outer space); what that 'thing' is can't be described, it is nothing.


If "Space is nothing", then it can have no properties, to say "Nothing doesn't expand" is to attribute a property to nothing, and that is what is an absurdity.

I didn't attribute a property, I negated one. I said 'Space DOES NOT expand' not that it DOES expand. The only 'property' I've attributed to nothing is the name (ie nothing). You OTOH have been the one saying space is something (under GR) which van expand, curve and contract. How so ? Only matter does and we see it everyday, starting from balloons expanding when blown up.


If you say space is nothing BUT the total of spatial relations between objects, then we observe that the spatial relations between distant objects in the Universe are expanding in accordance with the prediction of the theory of General Relativity. If in fact, space is nothing, then the positions and other properties of objects are only meaningful relative to other objects, and their relative movement is only meaningful relative to the passage of time. If you mathematically model these relations between objects, and between these objects and time, guess what? You get a four dimensional space-time model that corresponds to observations, and it predicts that the spatial relationships should expand over time, and then if you take a look to see if that is the case, you find that the observations confirm the prediction.

Spatial relationships between object can 'expand' (the better word is increase) over time not space. Spatial relationship is a property of objects in space; don't confuse it with space.

Here's an analogy.

If there's 2m between me and a bucket I won't say space expands because by another metric the distance is 200cm. Neither would the spatial relationship expand (increase) so doing save if the bucket is then 3m from me. The spatial relationship between both objects increases but not space itself.


Nope, you just don't understand what an analogy is.

*sighs*


I already answered that question, all of the associated observations corroborate the prediction that space-time is actually expanding, (ie. in real, observable terms).

And stars show that huh ? So far you haven't disagreed that space as nothing doesn't expand. You appear to have redefined space as something and say it has been shown to expand using time dilation in stars. But this avoids my logic.
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JohnPaul
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1/31/2014 1:38:25 PM
Posted: 2 years ago
At 1/31/2014 8:38:19 AM, Iredia wrote:
At 1/30/2014 10:10:12 PM, JohnPaul wrote:
At 1/30/2014 7:35:18 PM, Iredia wrote:
At 1/30/2014 8:06:15 AM, chui wrote:

If galaxies move through space, how do you reconcile this with the established fact that the velocity of a galaxy is proportional to distance for all galaxies (except for the few close galaxies). What gave the galaxies their energy and kept them all moving in a non random fashion? If galaxies move through space I would expect their motion to be more like the random motion of gas atoms.

I think this a rhetorical question. In any case, galaxies moving through space hardly contradicts the velocities observed: it does however contradict what GR prescribes the galaxies velocities musn't exceed (lightspeed). Dark energy_it seems_has been proposed as what is responsible for galaxies moving the way they do and gravity operates differently in outer space (eg weightlessness and differences in fire appearance) so you shouldn't expect galaxies to move a la Brownian motion.

What do you mean by "gravity operates differently in outer space"?

The effect of gravity on matter is different. For example, gravity is lesser in outer space so you feel weightless. Air can't be set up BY GRAVITY in convection currents so fires are different (concentric not wavy). Of course, it still remains an attractive force.

What are you talking about? Gravity from any source follows the same inverse square law everywhere. Are you confusing weight with mass? Objects in outer space are "weightless" only because they are moving freely in a gravitational field. You can become weightless simply by jumping off the roof of a house---until you hit the ground and experience weight again. And how can fires exist in outer space with no atmosphere to support combustion? If you can demonstrate any of your claims, you are ready for a Nobel Prize and will become world-famous. When do you plan to publish?
Iredia
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1/31/2014 3:17:45 PM
Posted: 2 years ago
At 1/31/2014 1:38:25 PM, JohnPaul wrote:

What are you talking about? Gravity from any source follows the same inverse square law everywhere.

Yes. But precisely because of that inverse square law the force of gravity acts differently on objects: the further the objects are from each other, the lesser the gravitational attraction between them.

Are you confusing weight with mass? Objects in outer space are "weightless" only because they are moving freely in a gravitational field. You can become weightless simply by jumping off the roof of a house---until you hit the ground and experience weight again.

No, when jumping of a roof you don't become weightless. Gravity still acts on you and pulls you to the ground. You are correct in a sense but you misunderstand what I mean by weightless in space. This involves gravitational acceleration during a free-fall (felts as weight) which is weaker. This was all to obvious in how high Armstrong and co. could jump on the moon before falling back_despite their heavy spacesuits.

And how can fires exist in outer space with no atmosphere to support combustion?

wiki.answers.com/Q/Is_there_fire_in_outer_space

Spacecrafts in outer space have an internal atmosphere for astronauts so combustion can still occur.

If you can demonstrate any of your claims, you are ready for a Nobel Prize and will become world-famous. When do you plan to publish?

Crap !
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JohnPaul
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1/31/2014 3:57:31 PM
Posted: 2 years ago
At 1/31/2014 3:17:45 PM, Iredia wrote:
At 1/31/2014 1:38:25 PM, JohnPaul wrote:

What are you talking about? Gravity from any source follows the same inverse square law everywhere.

Yes. But precisely because of that inverse square law the force of gravity acts differently on objects: the further the objects are from each other, the lesser the gravitational attraction between them.

Are you confusing weight with mass? Objects in outer space are "weightless" only because they are moving freely in a gravitational field. You can become weightless simply by jumping off the roof of a house---until you hit the ground and experience weight again.

No, when jumping of a roof you don't become weightless. Gravity still acts on you and pulls you to the ground. You are correct in a sense but you misunderstand what I mean by weightless in space. This involves gravitational acceleration during a free-fall (felts as weight) which is weaker. This was all to obvious in how high Armstrong and co. could jump on the moon before falling back_despite their heavy spacesuits.

And how can fires exist in outer space with no atmosphere to support combustion?

wiki.answers.com/Q/Is_there_fire_in_outer_space

Spacecrafts in outer space have an internal atmosphere for astronauts so combustion can still occur.

If you can demonstrate any of your claims, you are ready for a Nobel Prize and will become world-famous. When do you plan to publish?

Crap !

I still don't see what you are talking about. Of course the moon has less gravity than the earth because the moon has less mass. That has nothing to do with its being in "outer space" or its distance from the earth. Here is Newton's Law of Gravity: "Every particle in the universe attracts every other particle with a force directly proportional to the product of their masses and inversely proportional to the square of the distance between them" or as a formula (m1 m2)/d^2. Is there anything about this you disagree with?

No "weight" is experienced when moving freely in a gravitational field, only mass and acceleration. That is what "weightless" means.

The interior of a spaceship is not exactly in "outer space."
Iredia
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1/31/2014 5:34:54 PM
Posted: 2 years ago
At 1/31/2014 3:57:31 PM, JohnPaul wrote:

I still don't see what you are talking about. Of course the moon has less gravity than the earth because the moon has less mass. That has nothing to do with its being in "outer space" or its distance from the earth. Here is Newton's Law of Gravity: "Every particle in the universe attracts every other particle with a force directly proportional to the product of their masses and inversely proportional to the square of the distance between them" or as a formula (m1 m2)/d^2. Is there anything about this you disagree with?

No "weight" is experienced when moving freely in a gravitational field, only mass and acceleration. That is what "weightless" means.

The interior of a spaceship is not exactly in "outer space."

Crap ! For Chrissakes read Wikipedia to know what weight (and weightless) connotes. You don't see what I'm talking about yet you respond to it_dissapointing.
Porn babes be distracting me. Dudes be stealing me stuff. I'm all about the cash from now. I'm not playing Jesus anymore.
JohnPaul
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1/31/2014 5:48:06 PM
Posted: 2 years ago
At 1/31/2014 5:34:54 PM, Iredia wrote:
At 1/31/2014 3:57:31 PM, JohnPaul wrote:

I still don't see what you are talking about. Of course the moon has less gravity than the earth because the moon has less mass. That has nothing to do with its being in "outer space" or its distance from the earth. Here is Newton's Law of Gravity: "Every particle in the universe attracts every other particle with a force directly proportional to the product of their masses and inversely proportional to the square of the distance between them" or as a formula (m1 m2)/d^2. Is there anything about this you disagree with?

No "weight" is experienced when moving freely in a gravitational field, only mass and acceleration. That is what "weightless" means.

The interior of a spaceship is not exactly in "outer space."

Crap ! For Chrissakes read Wikipedia to know what weight (and weightless) connotes. You don't see what I'm talking about yet you respond to it_dissapointing.

I did read about it, first in high school Physics, then again many times when I majored in Physics in college. I do know what I am talking about. The question is, do you? I am not trying to pick on you. I am simply trying to understand what you meant to say.
JohnPaul
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1/31/2014 7:31:44 PM
Posted: 2 years ago
At 1/31/2014 5:48:06 PM, JohnPaul wrote:
At 1/31/2014 5:34:54 PM, Iredia wrote:
At 1/31/2014 3:57:31 PM, JohnPaul wrote:

I still don't see what you are talking about. Of course the moon has less gravity than the earth because the moon has less mass. That has nothing to do with its being in "outer space" or its distance from the earth. Here is Newton's Law of Gravity: "Every particle in the universe attracts every other particle with a force directly proportional to the product of their masses and inversely proportional to the square of the distance between them" or as a formula (m1 m2)/d^2. Is there anything about this you disagree with?

No "weight" is experienced when moving freely in a gravitational field, only mass and acceleration. That is what "weightless" means.

The interior of a spaceship is not exactly in "outer space."

Crap ! For Chrissakes read Wikipedia to know what weight (and weightless) connotes. You don't see what I'm talking about yet you respond to it_dissapointing.

I did read about it, first in high school Physics, then again many times when I majored in Physics in college. I do know what I am talking about. The question is, do you? I am not trying to pick on you. I am simply trying to understand what you meant to say.
EDIT - I now see that Wikipedia does give a "common" definition of weight as the attraction of gravity on an object, so I humbly apologize for my attack on your use of words. However, Wikipedia also very clearly states that an object moving freely in a gravitational field is "weightless" and distinguishes between weight and mass.