Galileo

[hecd2]

From what I understand, motion through space
was identified as absolute because space was believed to be an absolute, stationnary frame.

Perhaps, but absolute motion was undermined as a result of work done by Galileo (isn’t that appropriate given the title of the thread) a long time ago. Galilean transformations allow one to transform between two inertial frames in relative motion.

However, since space cannot be detected (although some experiments did try to look for such a medium) there was always the option in thinking that a certain body was stationnary,relative to this absolute space, making the body itself an absolute static frame. The earth was believed to be such a body by some, while Galileo opt for the sun.

here’s a quote from Newton :

“ Absolute space, in its own nature, without regard to anything external, remains always similar and immovable. Relative space is some movable dimension or measure of the absolute spaces; which our senses determine by its position to bodies: and which is vulgarly taken for immovable space …
Absolute motion is the translation of a body from one absolute place into another: and relative motion, the translation from one relative place into another

“Space” is not the same as frames of reference. I agree that the concept of absolute space existed up until the turn of the 19th Century, but what is an absolute frame of reference?

[With regard to the Airy experiment]I will try to get some info on this, for I’m still not certain what you’re saying. While you seem to be saying that the path is independant of the transverse velocity of the source, you still seem to be saying, from what I understand, the effect arises from the tranverse velocity of the observer, perpendicular to the path of light.

That is exactly what I am saying. Hooray!

However, it seems that if the star (source of light ) has also a
transverse velocity (relative to the observer) the path of light cannot be perpendicular to the observer, unless we re- introduce the concept of an luminous ether.

First of all there is no such thing as a perpendicular between a line (the path of light) and a point (the observer). Secondly, the light, independent of the transverse velocity of the source follows a geodesic (approximately a straight line) between the source and the observer - the source emits light in 4-pi steradians ie in all directions. Only the light that arrives directly from where the source was at the moment of the emission and where the observer is at the moment of detection is observed, and the observer can have a transverse velocity perpendicular to this or any other light path. This has nothing to do with the aether.

Alec
evolutionpages.com

You always leave my signature at the bottom of your replies. Would you mind deleting it please, as a casual reader might imagine that I have written your posts, and I wouldn’t like taht misunderstanding at all.

Alec
evolutionpages.com

 

[hecd2]

Thank you for this very detailed explanation. I have a question however. What if the earth does not rotate on it’s own, but is totally dependant to the spacetime gravitational effect upon the body?
In such a case, it would seem the magnetude would be equivalent as well. That is, since the space time would be causing the earth to rotate, to claim the
Coriolis effect is caused by the earth rotating, which itself is caused by the spacetime curvature close to the body, or to claim the earth is at rest and the Coriolis effect is caused directly by the spacetime seems to be a case for equivalence principle…Again, I’m not sure I’m understanding this properly.

I’m afraid I haven’t got a clue what you are talking about. I can usually get a handle on what you mean, even if the idea is bizarre, but this time I just don’t understand what you are saying. Rotation is a parameter that is free to adopt whatever value (vector) the physical history of the body dictates, such as collisions, close encounters, initial rotation and other contingent causes. It has nothing to do with being in a spacetime curvature.

Alec
evolutionpages.com

 

[StAnastasia]

You always leave my signature at the bottom of your replies. Would you mind deleting it please, as a casual reader might imagine that I have written your posts, and I wouldn’t like taht misunderstanding at all.
Alec]

Alec, I’m glad you pointed that out. I was worried that your posts were drifting more and more into incoherent YEC geocentrist gibberish, and I thought we were beginning to lose you to the Dark Side!

StAnastasia

 

[buffalo]

Alec, I’m glad you pointed that out. I was worried that your posts were drifting more and more into incoherent YEC geocentrist gibberish, and I thought we were beginning to lose you to the Dark Side!

StAnastasia

I would argue that scientism alone is the dark side. It is not illuminated by light.

 

[StAnastasia]

I would argue that scientism alone is the dark side. It is not illuminated by light.

Buffalo, there are at least two dark sides: (1) scientistic monism, in which all moral, aesthetic, and religious truth is swallowed up by the hegemony of a logically positivistic scientisim, and (2) biblically literalistic fundamentalism, in which all our “knowledge” about the world must conform literally to the now irrelevant world view of an ancient, prescientific, nomadic tribe.

StAnastasia

 

[buffalo]

Buffalo, there are at least two dark sides: (1) scientistic monism, in which all moral, aesthetic, and religious truth is swallowed up by the hegemony of a logically positivistic scientisim, and (2) biblically literalistic fundamentalism, in which all our “knowledge” about the world must conform literally to the now irrelevant world view of an ancient, prescientific, nomadic tribe.

StAnastasia

(2) biblically literalistic fundamentalism, in which all our “knowledge” about the world must conform literally to the now irrelevant world view of an ancient, prescientific, nomadic tribe.

I would agree with you except for one big thing - they were inspired by God. If Revelation were not part of this whole thing, then we would be left to our own human limitations. Fortunately, God saw where this might lead and decided to educate us.

The question is - who ya gonna believe?

 

[grannymh]

Buffalo, there are at least two dark sides: (1) scientistic monism, in which all moral, aesthetic, and religious truth is swallowed up by the hegemony of a logically positivistic scientisim, and (2) biblically literalistic fundamentalism, in which all our “knowledge” about the world must conform literally to the now irrelevant world view of an ancient, prescientific, nomadic tribe.

StAnastasia

Say what?

The ancient, prescientific, nomadic tribe, whose writings I read, definitely did not have an irrelevant world view. Not only were they speaking about truths far beyond the literal sense, they presented these truths in a variety of styles, written by a variety of people, in a variety of geographic locations over a variety of historical periods in which, despite being prescientific, mighty civilizations rose which had running water from one location to another. The real truths presented by this nomadic tribe are quite relevant to the world today.

Regarding real truths, the Bible means: basic instrutions before leaving earth
.

 

[StAnastasia]

The ancient, prescientific, nomadic tribe, whose writings I read, definitely did not have an irrelevant world view. Not only were they speaking about truths far beyond the literal sense, they presented these truths in a variety of styles, written by a variety of people, in a variety of geographic locations over a variety of historical periods in which, despite being prescientific, mighty civilizations rose which had running water from one location to another. The real truths presented by this nomadic tribe are quite relevant to the world today.

Grannymh, you are speaking differently here than most do on Catholic Answers, when you suggest that the bible is a complex document with a long compositional history, that we do not always interpret literally. However, do not confuse two differewnt sense of “worldview”:

(1) Do you accept that the earth is a flat plate, with pillars at the edges supporting the dome of the sky? Do you accept that this dome has holes poked in it to let the sun, moon and stars shine in? Do you believe literally that there are storehouses above the firmament containing rain, hail and snow? If you don’t believe these things, you don’t accept the ancient (cosmological) world view of a the nomadic Hebrew tribes.

(2) If you accept a worldview in which God sustains creation, calls human beings into relationship with God, becomes incarnate for the redemption of the world, and promises a new creation, then it seems you accept the biblical worldview, even if not its prescientific cosmological articulation.

StAnastasia

 

[StAnastasia]

(2)I would agree with you except for one big thing - they were inspired by God. If Revelation were not part of this whole thing, then we would be left to our own human limitations. Fortunately, God saw where this might lead and decided to educate us.
The question is - who ya gonna believe?

I will believe Caesar with respect to what is Caesar’s, and God with respect to what is God’s.

 

[mich2]

Three points - first, the model is a model of the universe as it is now, not how we observe it through the phenomenon of finite light speed. It is not irrelevant.

I would say that it’s ok to use this model as long as we also specify that such a model is unobservable, that is, such an universe does not affect our locality whatsoever. This is the reason why I still believe the model to be irrelevant. However, I agree the model can be used in trying to imagine what the universe might look now; but we have no observable means of proving this.

Second, all mass that is on the sphere has a gravitational influence, however infinitesimal, on earth.

Unless the speed of gravity is infinite,whch, so far is believed to be no greater, if not equal to that of light. I can’t personally see this, unless you could clarify as to what you mean by this.

Third, in the Machian view, it is the influence of the weighted average of all the masses in the universe that determines the orientation of an inertial frame, which is very important - Mach says “mass there determines inertia here”.

I would suspect it means all mass in the observable universe, and I agree to Mach’s statement. Isn’t he saying that the rotation of the earth is due to the influence of every mass in the universe? Would this imply that GR 's spacetime curvature is responsible for the rotation of the earth?

This is good - you are basically reconstructing the idea that leads to the concept of the CMB being pervasively present from all directions.

Personally, I question my using a cone as a model.
Yes;by observing the CMB from all direction would imply that we would be observing the centre of the universe from all directions as well due to the spacetime curvature. This would, in my opinion imply a great deal of gravitational lensing though. Do we have evidence of this?

Note that in the sphere model, as the surface retracts to a point, information comes to us from all directions on the surface of the distorted “sphere-bob” - ie in three dimensions, information from the origin comes to us from all directions of space. We don’t observe the centre because it is masked by the opacity of the coupling of photons and matter before decoupling occurred at about 379,000 years after Big Bang. At that time photons were released and we observe the CMB in whatever direction we look.

ok.

No, you shouldn’t necessarily keep them to yourself, but I think you should do a basic sense check on them before you post them. It’s unfair to rely on others to do your basic sense checking for you.

I try to do this, in a way that when I try to argue for the model of the earth being the center of the universe, using this as an equvilance principle purpose only, I do look for information. As for the ideas I might personal have of gravity, I don’t have any developed hypothesis…there just floating ideas. If I did have a great motivation in developping such thoughts, I would indeed look more for the answers, but I don’t. By sharing such thoughts with you was more than enough. You gave me most of the answers.Again, I am not trying to evolve any hypothesis, but am mearly daydreaming at times concerning those issues.

Well actually, no - the helium atom is slightly less massive than the sum of its parts, so the fusion of hydrogen into helium releases energy, rather than consuming it, because in the creation of a hydrogen atom, mass is annihilated and energy is released. That is how a hydrogen bomb works and how fusion reactors to produce energy for society by the fusion of hydrogen into helium will work. In every case, no matter what the mass of the atom, the total energy that can be released by the annihilation of the atom is equal to mc^2 where m is the mass of the atom and c is the speed of light.
In other words, you are suggesting that the Newtonian conception that links the mass, the distance and gravitational force between objects, F=(G x m1 x m2)/r^2, is flawed.

very good…thanks.

Now don’t you think that if there was an anomaly between the mass and the surface gravity of the sun, a few scientists might have noticed? As I have said, you are an intelligent guy, who seems to spending his energy in producing hopeless hypotheses to save geocentrism. I’d like to help you use your energy more effectively, so I’m not going to tell you why the fact that the mass of the sun is 333,000 times that of earth while its surface gravity is 28 times that of the earth is entirely consistent with well understood classical theory. Having answered so many of your hypotheses, I think I am entitled to ask you to do some homework. You are perfectly capable of doing it, and in doing it, you will learn some real physics.

Very true…I forgot to impliment the sun and earth’s surface area …thanks again

Well, that’s a false dichotomy. I think that geocentrism is wrong, but that doesn’t mean that I think the sun occupies an absolute rest frame.

I know that you don’t, Alec; just as Steven Hawkins…but did Galileo believe the same as you and dr, Hawkins?

Andre

 

[mich2]

Perhaps, but absolute motion was undermined as a result of work done by Galileo (isn’t that appropriate given the title of the thread) a long time ago. Galilean transformations allow one to transform between two inertial frames in relative motion.

Well, we know that Newton came after Galileo, which would mean, I assume, that Galileo believed in an absolute stationary spacial frame of reference. He certainly did also believe in relative motions between frames as well…so did Newton.

“Space” is not the same as frames of reference.

.

Absolute space would be one frame of reference, yes.

I agree that the concept of absolute space existed up until the turn of the 19th Century, but what is an absolute frame of reference?

I believe I wrote “absolute stationnary frame of reference”. If I made a mistake, I apologize.

That is exactly what I am saying. Hooray!
First of all there is no such thing as a perpendicular between a line (the path of light) and a point (the observer). Secondly, the light, independent of the transverse velocity of the source follows a geodesic (approximately a straight line) between the source and the observer - the source emits light in 4-pi steradians ie in all directions. Only the light that arrives directly from where the source was at the moment of the emission and where the observer is at the moment of detection is observed, and the observer can have a transverse velocity perpendicular to this or any other light path. This has nothing to do with the aether.

I’m still foggy on this, but you did clarify it abit…thanks.

You always leave my signature at the bottom of your replies. Would you mind deleting it please, as a casual reader might imagine that I have written your posts, and I wouldn’t like taht misunderstanding at all.

I’m sorry; I didn’t mean to cause any misunderstandings…I will do as you say.

Andre

 

[mich2]

I’m afraid I haven’t got a clue what you are talking about. I can usually get a handle on what you mean, even if the idea is bizarre, but this time I just don’t understand what you are saying. Rotation is a parameter that is free to adopt whatever value (vector) the physical history of the body dictates, such as collisions, close encounters, initial rotation and other contingent causes. It has nothing to do with being in a spacetime curvature.

Alec
evolutionpages.com

It’s actually basically the Mach’s principle. I certainly agree that physical force can indeed accelerate an object as well. However, it seems that if such a force is applied, the new inertial momentum given to body will eventually be corrected by the spacetime surrounding the body.
While it’s true that Newton predicts the body will remain inertial until an outside force changes it’s momentum, this postulate exists is in the absence of gravity.

Andre

 

[gym33karate]

Galileo was put under house arrest for the rest of his life by the catholic church because he siad the moon had flaws. the church said everything made by the lord is prefect so it can’t be flawed. they forced him to take back his statement and then put him under house arrest. he was able to see the flaws with this invented microscope. the church later said they were sorry to him a long while after he passes away while in house arrest

 

[Domini_servus]

The truth about Galileo

traditioninaction.org/History/A_003_Galileo.html

 

[mich2]

The truth about Galileo

traditioninaction.org/History/A_003_Galileo.html

Good link, Domini

Andre

 

[hecd2]

I would say that it’s ok to use this model as long as we also specify that such a model is unobservable, that is, such an universe does not affect our locality whatsoever.

It’s not a model so much as an analogy to explain how an expanding universe can lack a centre, and how the speed of recession of an object can be proportional to its distance no matter where you are. It’s not meant to be a realistic model of the universe - it lacks a whole dimension for a start.

This is the reason why I still believe the model to be irrelevant.

It is not irrelevant as an illustration of an expanding universe.

However, I agree the model can be used in trying to imagine what the universe might look now; but we have no observable means of proving this.

That is correct up to a point.Our knowledge of how the universe looks now contains extrapolations and predictions because the further away we look, the further back in time we see. History recedes with distance. Our consensus view of the current universe has recently changed by the discovery that the expansion of the universe is currently accelerating. Having said that,as in all science, we think that the universe is well behaved and describable, and we should be able to develop a mathematical model of reality that accurately describes the evolution of the universe.Various solutions of the Einstein field equations attempt to do just that.

Unless the speed of gravity is infinite,whch, so far is believed to be no greater, if not equal to that of light. I can’t personally see this, unless you could clarify as to what you mean by this.

You are right - I should have said: all mass that is on the *observable *sphere has a gravitational influence, however infinitesimal, on earth.

I would suspect it means all mass in the observable universe, and I agree to Mach’s statement. Isn’t he saying that the rotation of the earth is due to the influence of every mass in the universe?

It possibly means all mass in the observable universe - see above. But I don’t think Mach was quite clear about he meant, or, more likely, I don’t understand what he meant; certainly, if the influence of matter is the cause of inertia, it is an effect neither quantified nor part of either Newtonian or Einsteinian mechanics. It is more metaphysical - we observe that the arrow of inertia aligns closely with the star field, but whether that is a cause or an effect is difficult to determine. No-one can say how a single body rotating in a universe otherwise without matter would behave, or whether the concept of rotation is even meaningful in such a universe. However, in this universe, rotation is meaningful and observed.

Secondly, Mach was not saying that the rotation of the earth is due to matter elsewhere - he was saying that the arrow of inertia and the effects of rotation with respect to an inertial frame depend on matter elsewhere.

Would this imply that GR 's spacetime curvature is responsible for the rotation of the earth?

No - the rotation of the earth is caused by its history, like the rotation of a top is caused by its history - it is not caused by spacetime curvature - in fact I can’t see how the rotation of any body can be caused by spacetime curvature.
Personally, I question my using a cone as a model.

Yes;by observing the CMB from all direction would imply that we would be observing the centre of the universe from all directions as well due to the spacetime curvature.

No, you misunderstand. The observation of centre of the universe does not imply or require spacetime curvature. The analogy is using a 2-sphere in 3D space whereas the real universe is a 3-solid in 4D space. There is no centre to the universe, but we observe events near t=0 from all directions since all space and time was embedded in a small volume that has since expanded. In the case of the analogy, imagine light that started to propagate on the surface when the sphere was minute. In the absence of absorption, the same photons are still propagating on the surface from all directions.

This would, in my opinion imply a great deal of gravitational lensing though. Do we have evidence of this?

No need for gravitational lensing.

Alec
evolutionpages.com

 

[hecd2]

Well, we know that Newton came after Galileo, which would mean, I assume, that Galileo believed in an absolute stationary spacial frame of reference. He certainly did also believe in relative motions between frames as well…so did Newton.

In Galilean and Newtonian mechanics, the laws of physics are identical in any non-accelerating frame. That is an equivalence claim. Newton held an absolute space - ie one which was completely describable by Euclidean geometry and unaffected by external bodies. He also acknowledged that there was no way that we can determine the absolute rest frame or whether a body is static or moving with respect to that frame.He might have been a metaphysical absolutist, but he was a pragmatic relativist.

I’m still foggy on this, but you did clarify it abit…thanks.

(This is with regard to the aberration of starlight). Is there anything else I can do to clarify this? It is certainly the case that stellar aberration does NOT show anything about the motion of the source, and only about the motion of the observer with respect to the line joining the source and observer. That is why stellar aberration is uniformly the same across all sources (depending only on ecliptic latitude), regardless of their velocity with respect to other objects in the Universe.

Alec
evolutionpages.com

 

[hecd2]

It’s actually basically the Mach’s principle. I certainly agree that physical force can indeed accelerate an object as well. However, it seems that if such a force is applied, the new inertial momentum given to body will eventually be corrected by the spacetime surrounding the body.
While it’s true that Newton predicts the body will remain inertial until an outside force changes it’s momentum, this postulate exists is in the absence of gravity.

Spacetime curvature does not impose roatation on bodies. All I can do is repeat what I wrote before:

Rotation is a parameter that is free to adopt whatever value (vector) the physical history of the body dictates, such as collisions, close encounters, initial rotation and other contingent causes. It has nothing to do with being in a spacetime curvature.

Alec
evolutionpages.com

 

[mich2]

It’s not a model so much as an analogy to explain how an expanding universe can lack a centre, and how the speed of recession of an object can be proportional to its distance no matter where you are. It’s not meant to be a realistic model of the universe - it lacks a whole dimension for a start.

ok; However, I would personally view the farthest galaxies as being closer to some sort of centre. The image of the sphere used as an analagy of an expanding universe is fine; however, the surface of the sphere itself, in my opinion, would represent only one dimention of time, whereas, in order to fully represent our spacetime universe, it would seem that we ought to include the whole volume of the sphere, and not simply it’s surface.

It is not irrelevant as an illustration of an expanding universe.

I agree.

That is correct up to a point.Our knowledge of how the universe looks now contains extrapolations and predictions because the further away we look, the further back in time we see. History recedes with distance. Our consensus view of the current universe has recently changed by the discovery that the expansion of the universe is currently accelerating. Having said that,as in all science, we think that the universe is well behaved and describable, and we should be able to develop a mathematical model of reality that accurately describes the evolution of the universe.Various solutions of the Einstein field equations attempt to do just that.

I agree

. It possibly means all mass in the observable universe - see above. But I don’t think Mach was quite clear about he meant, or, more likely, I don’t understand what he meant; certainly, if the influence of matter is the cause of inertia, it is an effect neither quantified nor part of either Newtonian or Einsteinian mechanics.

I don’t know; if he meant the inertia of a body is determined in relation to all other bodies in the universe , I think that both the Newtonian (gravitational force) and especially the spacetime of GR (since Einstein was interested in Mach’s principle), can fit this description.
It seems that Mach was simply against the notion of an absolute stationnary space frame.

It is more metaphysical - we observe that the arrow of inertia aligns closely with the star field, but whether that is a cause or an effect is difficult to determine. No-one can say how a single body rotating in a universe otherwise without matter would behave, or whether the concept of rotation is even meaningful in such a universe. However, in this universe, rotation is meaningful and observed.

I fully agree; this was indeed his understanding. If you don’t mind, I would like to share my thoughts to this particular point.
In my opinion, a single body in space could indeed rotate and feel the centrifugal forces eventhough no other mass would be present.
If I think of a single body of mass, let it be someone in a spaceship, who starts the engine and then releases a great deal of energy from the engine ( steps on the gas pedal), a non-inertial system would exist, being a force of acceleration being experienced within the frame of reference. The way I view a non-inertail frame is simply a situation where a part of the frame accelerates (changes velocity) and part of the frame resists the acceleration. In other words, if small engines could be attached on all of the atoms within the frame, while an acceleration would exist during the engines release of energy (although one could ask the question “relative to what?”), I would think that the whole system would remain inertial, as in the case of freefall, since, nowhere within the system, there would be a resistance to such a change in velocity.
Therefore, in the case of a body in rotation, since the center of the body turns more slowly than the surface, it would resist the surface velocity, creating a centrifugal force.

Secondly, Mach was not saying that the rotation of the earth is due to matter elsewhere - he was saying that the arrow of inertia and the effects of rotation with respect to an inertial frame depend on matter elsewhere.

While I agree, I think his answer to the question; what truly can be called the cause and effect, would be somewhat relative in nature…I maybe wrong in my assertion, here.

**All masses and all velocities, and consequently all forces, are relative. There is no decision about relative and absolute which we can possibly meet, to which we are forced, or from which we can obtain any intellectual or other advantage. (Mach, The Science of Mechanics, ch.2, vi-3, Open Court, 1960, 279) **

Andre

 

[mich2]

continued…

No - the rotation of the earth is caused by its history, like the rotation of a top is caused by its history - it is not caused by spacetime curvature - in fact I can’t see how the rotation of any body can be caused by spacetime curvature.

I do agree that the history of the body in question has a great deal to do with this, as space alone does not exist. I’m not implying that a body can cause immediate inertia to a distant body, since gravity also has a finite velocity. However, I am implying that whatever caused the earth to start to rotate in the first place, let it the Milky Way’s rotating galactic system, or whatever, the direct cause remains gravity, that is, spacetime. It is with this particular frame of argument that I ask, what are the causes and what are the effects? Is spacetime created by matter or does space time create matter? It is in this respect that I ask whether it is the earth that might be creating a spacetime vortex due to it’s rotation, or is it the vortex that makes the earth rotate? My personal opinion for now, would be that such is a relative question, which makes part of the equivalence principle.

No, you misunderstand. The observation of centre of the universe does not imply or require spacetime curvature. The analogy is using a 2-sphere in 3D space whereas the real universe is a 3-solid in 4D space. There is no centre to the universe, but we observe events near t=0 from all directions since all space and time was embedded in a small volume that has since expanded. In the case of the analogy, imagine light that started to propagate on the surface when the sphere was minute. In the absence of absorption, the same photons are still propagating on the surface from all directions.

The analogy you gave is good indeed. However, it seems that even in such a point of view, the light from the galaxie close to the time of the big bang carries information of a universe having a much greater spacetime curvature than the one we experience at this moment ,which, to my knowledge, ought to carry a telescopic type of imaged information.

Andre