Geocentrisim or Heliocentrism?

Zombrex

Soul Winner wrote: »

Nobody knows where the center of the universe is

Current scientific understanding (which is supported reasonably well) is that every point in the universe can be considered the "centre" since the universe is thought to be homogenus.

It is a bit like a circle. Imagine a circle and then pick the "middle" of the outside line, ie the point on the circumference that is equally distant on the left and right of that point.



Every point can be considered the middle of the line.

ISAW

Morbert wrote: »

I asked you what your issue with my post was. I.e. How is what you've said related to anything I've said.

Wolfsbane asked me how geocentrists use relativity. I said they don't as relativity would have to be wrong for geocentricism to be right, as relativity says the laws of physics are the same for all observers no matter where they are or how they are moving with respect to things. Do you agree or disagree that the theory of relativity says this?

No that the cosmological principle says it! Relativity is about measuring things. we assume the laws involved are the same everywhere. What I am suggesting is that that assumption isnt relativity but is used to arrive at it . it is a postulate an assumption. It doesn't prove it it begins by assuming it is true.

It is only if the laws of physics are the same throughout the universe that we can end up with no special observer. If for example inverse cubed gravity existed somewhere that observer would have a different view he would not get the same result to his experiments that others get and relativity therefore could not apply.

Actually relativity probably could apply. the observer would get a different result
but the principle of equivalance would not apply since he isnt under the same laws.

If we had instead been talking about the speed of light, and I said relativity says the speed of light is the same for all observers, would you say "Actually this isn't relativity because that is a postulate."?

Yes.
the speed of light in a vacuum being constant IS a postulate. We can indeed measure it and haven't been able to show it not to be constant. But there are theories.

It is a basic postulate of the theory of relativity that the speed of light is constant. This can be broken down into two parts:

* The speed of light is independent of the motion of the observer.
* The speed of light does not vary with time or place.
To state that the speed of light is independent of the velocity of the observer is very counter-intuitive.



And NO
If general relativity is correct, then the constancy of the speed of light in inertial frames is a tautology from the geometry of spacetime.
But it is NOT constant in an accelerating reference frame.

http://www.xs4all.nl/~johanw/PhysFAQ/Relativity/SpeedOfLight/speed_of_light.html

Soul Winner

Wicknight wrote: »

Current scientific understanding (which is supported reasonably well) is that every point in the universe can be considered the "centre" since the universe is thought to be homogenus.

So the ancients were right then? The earth is/or can be the center of the universe after all?

Morbert

ISAW wrote: »

No that the cosmological principle says it! Relativity is about measuring things. we assume the laws involved are the same everywhere. What I am suggesting is that that assumption isnt relativity but is used to arrive at it . it is a postulate an assumption. It doesn't prove it it begins by assuming it is true.

Firstly, general covariance is a stronger claim than the cosmological principle. General covariance is a rigorous claim about the symmetry of physical laws under transformations. The cosmological principle just says the universe is homogeneous on large scales.

Secondly, your suggestion is a very strange one. A scientific theory does not consist of "proven" claims. It consists of assertions that are supported by evidence and experiments. Newtonian mechanics does not prove F=ma. Instead, it postulates it, and the postulate is supported by evidence. Darwinian evolution does not prove the diversification of life is via natural selections of genetic mutations. It postulates it, and it the postulate supported by evidence. Similarly, the theory of relativity does not prove general covariance. It postulates it, and is supported by evidence.

Yes.
the speed of light in a vacuum being constant IS a postulate. We can indeed measure it and haven't been able to show it not to be constant. But there are theories.

It is a basic postulate of the theory of relativity that the speed of light is constant. This can be broken down into two parts:

* The speed of light is independent of the motion of the observer.
* The speed of light does not vary with time or place.
To state that the speed of light is independent of the velocity of the observer is very counter-intuitive.



And NO
If general relativity is correct, then the constancy of the speed of light in inertial frames is a tautology from the geometry of spacetime.
But it is NOT constant in an accelerating reference frame.

http://www.xs4all.nl/~johanw/PhysFAQ/Relativity/SpeedOfLight/speed_of_light.html

Well I will clarify that, by "speed of light", I am talking about local measurement of the speed of light.

But this doesn't answer my question. If we were talking about the speed of light, and I said relativity says the speed of light is the same for all observers, would you say "Actually this isn't relativity because that is a postulate."? I.e. Do you consider the postulates of [special] relativity to be part of the [special] theory of relativity?

ISAW

Soul Winner wrote: »

So the ancients were right then? The earth is/or can be the center of the universe after all?

Yes I would agree with Wickednight here but the whole thing is a consequence of what we mean by the terminology. which is why I tried to be clear about "Einstiens theory of" and Aristotles relativity.

Im reminded of a story by George Liuis Borges in which he was at a party and said something like "The Universe is a sphere whose centre is everywhere and whose circumference is nowhere" someone commented that that was very clever. Borges said "I dont think it is original maybe I saw it before" So being a Classics scholar he went and looked it up and found similar comments by Napoleon Caesar and Alexander. His conclusion? -Nothing is original!

Except the "first cause" I suppose

Morbert:
In Einstines original paper he took the example of a train carriage with "magic" doors that opened instantly when they detected light within. A lamp was in the exact middle of the carriage. It was turned on.
What does the observer in the carriage see? Well now moving at constant speed (non accelerating reference frame) is exactly the same as standing still. So he sees the light travel the same distance to each door and if we assume light always has the same speed the doors open simultaneously.

What does an observer outside see? Well the train is moving along say from left to right. when the light is tuyrned on the door on the Left hand is moving towards the light and the one on the right hand end away from it . So the light has to traqvel les to reach the left hand door. since the speed is always the same the light reaches the left hand door first and then the right hand door opens later.

But the second assumption was "we always get the same result". So how can simultaneous events not be simultaneous? Something funny is happening with time. They DO see differnt things relative to where they were but we have to make it so they don't! Einstein then applied mathematics to show exactly how funny the distortion was based on the speed of the train relative to the outside observer.

I'm just saying the philosophical assumptions are "equivalence principle" and a constant speed for light. I'm saying the theory depends on these but the mathematical explanation arrived at is what we call "Einstein's theory of Relativity" . In that way the theory is not the assumptions which underpin the theory.

Does that explain my position?

Zombrex

Soul Winner wrote: »

So the ancients were right then? The earth is/or can be the center of the universe after all?

Yes. A stopped clock is right twice a day after all :P

Morbert

ISAW wrote: »

Yes I would agree with Wickednight here but the whole thing is a consequence of what we mean by the terminology. which is why I tried to be clear about "Einstiens theory of" and Aristotles relativity.

Im reminded of a story by George Liuis Borges in which he was at a party and said something like "The Universe is a sphere whose centre is everywhere and whose circumference is nowhere" someone commented that that was very clever. Borges said "I dont think it is original maybe I saw it before" So being a Classics scholar he went and looked it up and found similar comments by Napoleon Caesar and Alexander. His conclusion? -Nothing is original!

Except the "first cause" I suppose

Morbert:
In Einstines original paper he took the example of a train carriage with "magic" doors that opened instantly when they detected light within. A lamp was in the exact middle of the carriage. It was turned on.
What does the observer in the carriage see? Well now moving at constant speed (non accelerating reference frame) is exactly the same as standing still. So he sees the light travel the same distance to each door and if we assume light always has the same speed the doors open simultaneously.

What does an observer outside see? Well the train is moving along say from left to right. when the light is tuyrned on the door on the Left hand is moving towards the light and the one on the right hand end away from it . So the light has to traqvel les to reach the left hand door. since the speed is always the same the light reaches the left hand door first and then the right hand door opens later.

But the second assumption was "we always get the same result". So how can simultaneous events not be simultaneous? Something funny is happening with time. They DO see differnt things relative to where they were but we have to make it so they don't! Einstein then applied mathematics to show exactly how funny the distortion was based on the speed of the train relative to the outside observer.

I'm just saying the philosophical assumptions are "equivalence principle" and a constant speed for light. I'm saying the theory depends on these but the mathematical explanation arrived at is what we call "Einstein's theory of Relativity" . In that way the theory is not the assumptions which underpin the theory.

Does that explain my position?

Well ok I understand your position but it is a very unconventional one. It would mean Newton's laws are not part of Newtonian mechanics. And quantum postulates are not part of quantum mechanics.

ISAW

Morbert wrote: »

Well ok I understand your position but it is a very unconventional one. It would mean Newton's laws are not part of Newtonian mechanics. And quantum postulates are not part of quantum mechanics.

Im reminded of Godels Paradox and the null set problem i..e does a null set contain itself ? You seem to be saying if you have an empty library with no actual books the index of the library will have a single entry "index of library" as opposed to not having any entries at all.

Morbert

ISAW wrote: »

Im reminded of Godels Paradox and the null set problem i..e does a null set contain itself ? You seem to be saying if you have an empty library with no actual books the index of the library will have a single entry "index of library" as opposed to not having any entries at all.

How am I saying this?

ISAW

Morbert wrote: »

How am I saying this?

You : Philosophical assumptions + arguments of theory + evidential observations + conclusions of theory = Theory = a complete field of "hard" science - by "hard" I mean based on logic reason and data handled in a formal manner e.g. Newtonian mechanics, quantum physics.

Firdt the Godel bit

Since we assume hard science is consistent and logical like mathematics there will be things in physics which are true but which we cant prove true .

http://en.wikipedia.org/wiki/G%C3%B6del%27s_incompleteness_theorems

or even prove untrue, given the modern bent for falsification

This kind of flies in the face of "if it cant be shown it ain't science"

Now the null set bit. Suppose the theory only has the assumptions and nothing else. Nobody has developed anything else yet. In your definition it is still a theory since the theory is the assumptions plus all the other stuff. If all the other stuff is zero we are left with an epistemological connundrum. Interesting!

Something curious about all this.
Maybe it is a "type error" I am making? I am pushed into thinking that a theory "about" dinosaurs is not itself a dinosaur.

http://www.scienceandchristianbelief.org/articles/dawkinspoole1.php
Coulson, who coined the phrase 'God - of - the - gaps', wisely recommended out of his Christian convictions that, 'When we come to the scientifically unknown, our correct policy is not to rejoice because we have found God; it is to become better scientists. For the scientific enterprise is based on a belief that gaps can be filled - but with scientific explanations, not with talk 'about' God. So there is a restricted sense in which it is true to say that science has no need for God, that talk about God is unnecessary in science. Its practitioners have chosen to confine science to physical observables and consequently talk about God forms no part of a scientific explanation.

Im left with - Is a "scientific philosophy about relativity" a different type a different kind of knowledge to "relativity"? Or if we include the philosophical basis with the other stuff are we not into a "turtles all the way down" senario?

I am genuinely intrigued by the conundrum you have raised with me and I will have to think about it a bit as I haven' resolved the cognitive conflict.

LOL Maybe I am right but it is impossible to prove it!

Zombrex

Morbert wrote: »

How am I saying this?

Yeah he does that a bit :P

Morbert

ISAW wrote: »

You : Philosophical assumptions + arguments of theory + evidential observations + conclusions of theory = Theory = a complete field of "hard" science - by "hard" I mean based on logic reason and data handled in a formal manner e.g. Newtonian mechanics, quantum physics.

Firdt the Godel bit

Since we assume hard science is consistent and logical like mathematics there will be things in physics which are true but which we cant prove true .

http://en.wikipedia.org/wiki/G%C3%B6del%27s_incompleteness_theorems

or even prove untrue, given the modern bent for falsification

This kind of flies in the face of "if it cant be shown it ain't science"

Now the null set bit. Suppose the theory only has the assumptions and nothing else. Nobody has developed anything else yet. In your definition it is still a theory since the theory is the assumptions plus all the other stuff. If all the other stuff is zero we are left with an epistemological connundrum. Interesting!

Something curious about all this.
Maybe it is a "type error" I am making? I am pushed into thinking that a theory "about" dinosaurs is not itself a dinosaur.

http://www.scienceandchristianbelief.org/articles/dawkinspoole1.php
Coulson, who coined the phrase 'God - of - the - gaps', wisely recommended out of his Christian convictions that, 'When we come to the scientifically unknown, our correct policy is not to rejoice because we have found God; it is to become better scientists. For the scientific enterprise is based on a belief that gaps can be filled - but with scientific explanations, not with talk 'about' God. So there is a restricted sense in which it is true to say that science has no need for God, that talk about God is unnecessary in science. Its practitioners have chosen to confine science to physical observables and consequently talk about God forms no part of a scientific explanation.

Im left with - Is a "scientific philosophy about relativity" a different type a different kind of knowledge to "relativity"? Or if we include the philosophical basis with the other stuff are we not into a "turtles all the way down" senario?

I am genuinely intrigued by the conundrum you have raised with me and I will have to think about it a bit as I haven' resolved the cognitive conflict.

LOL Maybe I am right but it is impossible to prove it!

Scientific theories are very different to formal systems of logic/grammar. The postulates of a theory are simply assertions that will be supported or falsified by investigation. The mathematics is there to make the postulates rigorously predictive. Special relativity says the laws of physics are invariant under lorentz transformations, and that the speed of light is locally the same for all observers. General relativity says the laws of physics are invariant under all smooth one-to-one spacetime transformations, and that gravity and acceleration are locally equivalent. These are the claims, and all the maths and geometry is there to explore the consequences of these claims, so that we can test them.

ISAW

Morbert wrote: »

Scientific theories are very different to formal systems of logic/grammar.

So you are saying scientific theories are not "hard" and depend on informal knowledge and

The postulates of a theory are simply assertions that will be supported or falsified by investigation.

But not proved true or false in a formal logical way? Only supported or falsified in some way which is "different to formal truth"

so to what kind of informal truth or flasification are you referring if it isnt that of logically true or false?

The mathematics is there to make the postulates rigorously predictive. Special relativity says the laws of physics are invariant under lorentz transformations, and that the speed of light is locally the same for all observers.

The derivation of special relativity depends not only on these two explicit postulates, but also on several tacit assumptions (made in almost all theories of physics), including the isotropy and homogeneity of space and the independence of measuring rods and clocks from their past history.http://en.wikipedia.org/wiki/Special_relativity#cite_note-9

As I have suggested this isnt what the theory says it is the assumptions from where it begins.

Only if you formally mathematically state it and then derive the transformations.

These are the claims, and all the maths and geometry is there to explore the consequences of these claims, so that we can test them.

They are assumptions not claims and based on formally stating them and assuming them true one can formally derive the transformations.
Now - what happened to
"Scientific theories are very different to formal systems of logic/grammar. "?

Morbert

I'm having trouble following your post, so I will respond to the bits I understand and think are relevant.

But not proved true or false in a formal logical way? Only supported or falsified in some way which is "different to formal truth"

so to what kind of informal truth or flasification are you referring if it isnt that of logically true or false?

I am referring to tentative inference. We can't ever prove relativity, we can only have great confidence in its efficacy. Most people (including myself when I'm not being too academic) refer to this confidence as an informal notion of "truth".

They are assumptions not claims and based on formally stating them and assuming them true one can formally derive the transformations.

The postulates are indeed claims. Newton was claiming that the acceleration, mass, and force experienced by a body obey the relationship F =ma. Schrödinger was claiming the state of a quantum system evolves in a unitary manner described by the Schrödinger equation. etc. These people were not simply claiming that the postulates imply certain things. They were claiming the postulates fit the observable world.

stevoslice

Bit late but

https://www.youtube.com/watch?v=kbynKfNfHk4

ISAW

Morbert wrote: »

Special relativity says ... the speed of light is locally the same for all observers. General relativity says ... gravity and acceleration are locally equivalent. These are the claims, and all the maths and geometry is there to explore the consequences of these claims, so that we can test them.

What do you mean by "local"?

does relativity also claim or prove there are no local causal effects?

It that a correct claim?

ISAW

Morbert wrote: »

I'm having trouble following your post, so I will respond to the bits I understand and think are relevant.



I am referring to tentative inference. We can't ever prove relativity, we can only have great confidence in its efficacy.

So science isn't "true" it is only "tentavive inference"
Surely it is more than that and is a valid description of the Universe?

If it is just tentative inference how is theology any less reasonable?

The postulates are indeed claims. Newton was claiming that the acceleration, mass, and force experienced by a body obey the relationship F =ma.

He derived that from the assumption of change in momentum when acted on by a force.

All mathematics can be reduced to set theory . Are you really saying that even though one can deducewmathematics for first principles the basic claims of set theory are the SAME as saying "3*2=6" or that Fermat's Principle theorem is true?

Schrödinger was claiming the state of a quantum system evolves in a unitary manner described by the Schrödinger equation. etc. These people were not simply claiming that the postulates imply certain things. They were claiming the postulates fit the observable world.

Let me be clear about my terms:
Relativity is a philosophy that there are not absolutes. Einstiens relativity is only "non absolute" in terms of measuring somehting else in motion. i.e. the postulate is for an observer in a particular place at a particular time and only related to looking at something else moving. It is NOT relative even internally to itself. e.g. the theory can derive the mass energy equivalence of the universe but the mass/energy of the universe may at the same time be absolute and constant

Morbert

ISAW wrote: »

So science isn't "true" it is only "tentavive inference"
Surely it is more than that and is a valid description of the Universe?

If it is just tentative inference how is theology any less reasonable?

I'm not concerned with theology. And yes, it is always tentative. A theory is always open to refutation while a mathematical theorem, once shown to be true, is true forever and always.

The postulates are indeed claims. Newton was claiming that the acceleration, mass, and force experienced by a body obey the relationship F =ma.

He derived that from the assumption of change in momentum when acted on by a force.

That is just an equivalent expression of the postulate. I.e. F = dp/dt. This postulate is not derived. It is a claim about the motion of bodies in the universe.

All mathematics can be reduced to set theory . Are you really saying that even though one can deducewmathematics for first principles the basic claims of set theory are the SAME as saying "3*2=6" or that Fermat's Principle theorem is true?

Again, I am not talking about fields of mathematics at all. Mathematics is about the exploration of logical inferences and implications. Scientific theories are about defining patterns the natural world operates under, and they do not follow from one another in the same way mathematical theorems do.

Let me be clear about my terms:
Relativity is a philosophy that there are not absolutes. Einstiens relativity is only "non absolute" in terms of measuring somehting else in motion. i.e. the postulate is for an observer in a particular place at a particular time and only related to looking at something else moving. It is NOT relative even internally to itself. e.g. the theory can derive the mass energy equivalence of the universe but the mass/energy of the universe may at the same time be absolute and constant

I am not referring to any philosophy of relativity. I am referring to the postulates of Einstein's theory of relativity. Relativity postulates general covariance in the same way that quantum mechanics postulates unitary time-evolution via the Schrodinger equation.

ISAW

Morbert wrote: »

Morbert wrote: »

I'm not concerned with theology. And yes, it is always tentative. A theory is always open to refutation while a mathematical theorem, once shown to be true, is true forever and always.

That is just an equivalent expression of the postulate. I.e. F = dp/dt. This postulate is not derived. It is a claim about the motion of bodies in the universe.

But if it is just a mathematical restatement of the postulate according to your above comment it is a statement of "something open to refutation" . You cant cl;aim the theory is not derived and also claim something in it is an "equivalent expression" i.e. "derived"

Again, I am not talking about fields of mathematics at all. Mathematics is about the exploration of logical inferences and implications. Scientific theories are about defining patterns the natural world operates under, and they do not follow from one another in the same way mathematical theorems do.

SO if the theory does not follow the postulate in this way it isnt an 2equivalent expression" ?
Which is it?

I am not referring to any philosophy of relativity. I am referring to the postulates of Einstein's theory of relativity. Relativity postulates general covariance in the same way that quantum mechanics postulates unitary time-evolution via the Schrodinger equation.

Either what we see as observed is explained as a logical formasl mathematical consequence of the formal definition /description of the postulastes or it isnt.

If you claim what we see is "equivalent" you either mean the whole thing can be reduced right back to the formal definition of the postulates or it cant.

Which is it?
Starting from the postulates the whole theory is formal like mathematics or it isn't and at some time science " does not follow from one another in the same way mathematical theorems do."

Morbert

ISAW, again I cannot follow your post, and would ask you to elaborate.

I am claiming the postulate F = dp/dt or, equivalently, F=ma is not derived from anything, but is instead an informal inference of how bodies behave that is open to refutation (indeed, it is not correct for high energies). Scientists, unlike mathematicians, only assume the postulate is true after it has been shown that it is consistent with observation.

I said: "Again, I am not talking about fields of mathematics at all. Mathematics is about the exploration of logical inferences and implications. Scientific theories are about defining patterns the natural world operates under, and they [theories] do not follow from one another in the same way mathematical theorems do." I.e. Quantum Mechanics is not derived from Newtonian mechanics, and in fact makes postulates that contradict Newtonian Mechanics. This is because scientific theories are sets of postulates and hypotheses, and do not constitute a logical grammar or a mathematical field. They are supported or falsified based on observation and experiment.

By your convention, the postulates of a theory are not part of the theory. I.e. Natural selection of Genetic mutations is not part of the theory of evolution, F=dp/dt is not part of the theory of Newtonian mechanics, and general covariance is not part of the theory of relativity. This convention makes little practical sense to me, and I know of nobody other than you who holds it.

ISAW

Morbert wrote: »

ISAW, again I cannot follow your post, and would ask you to elaborate.

I am claiming the postulate F = dp/dt or, equivalently, F=ma is not derived from anything, but is instead an informal inference of how bodies behave that is open to refutation

What do you mean by "informal" ? Surely it is a formal statement?

And it is derived for example
Momentum is mass times velocity
if the velocity at the beginning is u and at the end is v

the change in momentum is mv - mu m times v minus m times u

Taking that over time t THe change per second is (mv-mu) divided by t

Here is the derived part

mv-mu times t is the same as m times ( v-u) /t

since v minus u divided by t is acceleration you get Change of momentum over time equals mass times acceration.

F=ma is a FORMAL statement of that!

Back to the issue of science including itself.

I think the problem may be this:

http://en.wikipedia.org/wiki/Newton%27s_laws_of_motion
In the given interpretation mass, acceleration, momentum, and (most importantly) force are assumed to be externally defined quantities. This is the most common, but not the only interpretation: one can consider the laws to be a definition of these quantities.

Are you saying Newton's laws define what mass acceleration an inertial reference frame and force or are you saying they are external to Newtonian mechanics?

(indeed, it is not correct for high energies). Scientists, unlike mathematicians, only assume the postulate is true after it has been shown that it is consistent with observation.

In certain reference frames which only became defines AFTER Newton.

I said: "Again, I am not talking about fields of mathematics at all. Mathematics is about the exploration of logical inferences and implications. Scientific theories are about defining patterns the natural world operates under, and they [theories] do not follow from one another in the same way mathematical theorems do." I.e. Quantum Mechanics is not derived from Newtonian mechanics, and in fact makes postulates that contradict Newtonian Mechanics. This is because scientific theories are sets of postulates and hypotheses, and do not constitute a logical grammar or a mathematical field. They are supported or falsified based on observation and experiment

So
F=ma IS a formal statement of newtons second law
or
F=ma is NOT a formal statement of newtons second law

Which is it?

And we are also to assume Newtonian mechanics is NOT a logical grammar or a mathematical field?

By your convention, the postulates of a theory are not part of the theory. I.e. Natural selection of Genetic mutations is not part of the theory of evolution, F=dp/dt is not part of the theory of Newtonian mechanics, and general covariance is not part of the theory of relativity. This convention makes little practical sense to me, and I know of nobody other than you who holds it.

Butg according to the examples you give above they are formal restatements of the postulates and NOT new statements derived from them! You cant say the theory unlike mathematics or a formal system comes up with something new and then ALSO SAY that the theory is just a logical formal consequence of the postulates i.e. whatevert is stated is exactly the same as the postulates.

If it means exactly the same then it is a FORMAL derivation!
If it is "tacid" and not formal then you can not show it to formally mean the same and it stands aport from the assumption.

Do you get the idea I am putting across?

Science cant be wholly formal and also be wholly tacid. If it is a mixture of the two it cant be wholly formal so rest of the theory cant be derived from the postualtes and must stand apart from them. One cant say science is tacid and also say the theory is a direct translation of the postulate.

Morbert

ISAW wrote: »

What do you mean by "informal" ? Surely it is a formal statement?

And it is derived for example
Momentum is mass times velocity
if the velocity at the beginning is u and at the end is v

the change in momentum is mv - mu m times v minus m times u

Taking that over time t THe change per second is (mv-mu) divided by t

Here is the derived part

mv-mu times t is the same as m times ( v-u) /t

since v minus u divided by t is acceleration you get Change of momentum over time equals mass times acceration.

F=ma is a FORMAL statement of that!

Where did the F come from in your formal derivation? How would you formally derive/infer the statement "F = dp/dt"

I think the problem may be this:

http://en.wikipedia.org/wiki/Newton%27s_laws_of_motion
In the given interpretation mass, acceleration, momentum, and (most importantly) force are assumed to be externally defined quantities. This is the most common, but not the only interpretation: one can consider the laws to be a definition of these quantities.

Are you saying Newton's laws define what mass acceleration an inertial reference frame and force or are you saying they are external to Newtonian mechanics?

By "externally defined quantities", the Wiki quote was referring to F,m, and a, and not newton's laws. I.e. There is debate over whether or not force etc. should be defined externally to Newton's laws. I am saying F = dp/dt or, equivalently, F=ma, as a postulate of Newtonian mechanics, is a part of Newtonian mechanics.

In certain reference frames which only became defines AFTER Newton.

What?

So
F=ma IS a formal statement of newtons second law
or
F=ma is NOT a formal statement of newtons second law

Which is it?

Please show me where I said F=ma is not a "formal statement" and I will correct myself. F= dp/dt is an informal inference. I.e. F=dp/dt is not formally derived, but rather postulated.

And we are also to assume Newtonian mechanics is NOT a logical grammar or a mathematical field?

Yes. The mathematical field it employs is called real analysis.

Butg according to the examples you give above they are formal restatements of the postulates and NOT new statements derived from them! You cant say the theory unlike mathematics or a formal system comes up with something new and then ALSO SAY that the theory is just a logical formal consequence of the postulates i.e. whatevert is stated is exactly the same as the postulates.

I never said the theory is just a logical formal consequence of the postulates. I said the postulates are part of the theory, and are informal inferences about some aspect of nature. Just because they are informal inferences doesn't mean they cannot be rigorously stated so as to produce precise predictions. I.e. If we postulate that the relationship F=dp/dt holds, we can derive an equation of motion for a ball on a spring and see if it accurately predicts how such a system will behave. We don't derive F = dp/dt.

If it means exactly the same then it is a FORMAL derivation!
If it is "tacid" and not formal then you can not show it to formally mean the same and it stands aport from the assumption.

Do you get the idea I am putting across?

Science cant be wholly formal and also be wholly tacid. If it is a mixture of the two it cant be wholly formal so rest of the theory cant be derived from the postualtes and must stand apart from them. One cant say science is tacid and also say the theory is a direct translation of the postulate.

I said the postulates are informal inferences. I said nothing about theories as a whole.

Zombrex

Morbet I'm starting to get a bit of a man-crush on you

ISAW

Morbert wrote: »

Where did the F come from in your formal derivation? How would you formally derive/infer the statement "F = dp/dt"

Which is just saying that f=ma is a formal restatement of the postulate!

"The change in momentum over time is equal to the applied force"

By "externally defined quantities", the Wiki quote was referring to F,m, and a, and not newton's laws. I.e. There is debate over whether or not force etc. should be defined externally to Newton's laws.

Or whether it is defined within the laws? Are they? Care to rehearse the "debate" you mentioned?

F=ma, as a postulate of Newtonian mechanics, is a part of Newtonian mechanics.

Other than the postulates what ELSE is there?

What?

The reference frame idea came about after Newton even though you could say the first law define an absolute reference frame.

Please show me where I said F=ma is not a "formal statement" and I will correct myself. F= dp/dt is an informal inference. I.e. F=dp/dt is not formally derived, but rather postulated.

the idea that ma=dp/dt is

Yes. The mathematical field it employs is called real analysis.

Apart from the postulates () three laws of motion) and any formal derivations what ELSE has newtonian mechanics?
If you refer to gravity you have to add in more postulates.

I never said the theory is just a logical formal consequence of the postulates. I said the postulates are part of the theory, and are informal inferences about some aspect of nature. Just because they are informal inferences doesn't mean they cannot be rigorously stated so as to produce precise predictions.

What do you mean by "rigorously stated"? Formally stated?

I.e. If we postulate that the relationship F=dp/dt holds, we can derive an equation of motion for a ball on a spring and see if it accurately predicts how such a system will behave. We don't derive F = dp/dt.

But one does derive Force = mass* acceleration !

The second law only postulates Force = change of momentum over time and not that the change in momentum equals mass times acceleration.

I said the postulates are informal inferences. I said nothing about theories as a whole.

So what ELSE that is not a formal derivation from the three laws of motion is part of Newtonian mechanics?

Morbert

ISAW wrote: »

Which is just saying that f=ma is a formal restatement of the postulate!

"The change in momentum over time is equal to the applied force"

You did not answer my questions. Where did the F come from in your formal derivation? How would you derive the postulate "F=dp/dt"?

Or whether it is defined within the laws? Are they? Care to rehearse the "debate" you mentioned?

That debate doesn't interest me.

Other than the postulates what ELSE is there?

Apart from the postulates () three laws of motion) and any formal derivations what ELSE has newtonian mechanics?
If you refer to gravity you have to add in more postulates.

I'm not sure what you mean by "what ELSE"? What else would there be, other than postulates and their predictions?

The reference frame idea came about after Newton even though you could say the first law define an absolute reference frame.

Yes but what does this have to do with my post?

the idea that ma=dp/dt is.

But one does derive Force = mass* acceleration !

The second law only postulates Force = change of momentum over time and not that the change in momentum equals mass times acceleration.

So are you agreeing that the postulate F=dp/dt is not formally derived?

The line of reasoning:F = dp/dt = m dv/dt can be considered a derivation in a trivial sense. But this in no way implies Newton's second law, however it is expressed, is formally derived. It is informally inferred from the set of experimental data we have.

What do you mean by "rigorously stated"? Formally stated?

I normally associate formal statements with mathematical statements. And some postulates (especially outside of physics) are difficult to formulate mathematically without losing clarity (e.g. The postulates of Darwin's theory of evolution). But if "formal" extends to beyond mathematical statements then yes.

ISAW

Morbert wrote: »

You did not answer my questions. Where did the F come from in your formal derivation? How would you derive the postulate "F=dp/dt"?

Because it is stated in the law itself both "change in momentum" and " force" are mentioned

Acceleration times mass isn't mentioned F=dp/dt is stating the law F= ma is derived from
dp/dt being equal to ma

The Law does not state "the product of mass times acceleration is equal to the implied force"
[/quote]

That debate doesn't interest me.

Then why did you refer to it? "There is debate over whether or not force etc. should be defined externally to Newton's laws. " If they are not internal to the theory then the postulates refer to something else which is OUTSIDE of it?

I'm not sure what you mean by "what ELSE"? What else would there be, other than postulates and their predictions?

Well . If you are claiming that postulates are formally stated then anything formally derived from them is as you have maintained just a restatement of them.
So what part of the theory is there which is NOT a formal derivation from the postulate?

Yes but what does this have to do with my post?

You stated

Scientists, unlike mathematicians, only assume the postulate is true after it has been shown that it is consistent with observation.

in the case of newtonian mechanics as I stated it is true only for certain reference frames.

From the wiki reference I supplied
Newton's Laws hold only with respect to a certain set of frames of reference called Newtonian or inertial reference frames. Some authors interpret the first law as defining what an inertial reference frame is; from this point of view, the second law only holds when the observation is made from an inertial reference frame, and therefore the first law cannot be proved as a special case of the second.
Galili, I.; Tseitlin, M. (2003). "Newton's First Law: Text, Translations, Interpretations and Physics Education". Science & Education 12 (1): 45–73. doi:10.1023/A:1022632600805
and
http://www.lightandmatter.com/html_books/1np/ch04/ch04.html

Which culminated in two points which I raised elsewhere to which you asked "What"?:

1.The explicit concept of an inertial frame of reference was not developed until long after Newton's death.

2. In the given interpretation mass, acceleration, momentum, and (most importantly) force are assumed to be externally defined quantities. This is the most common, but not the only interpretation: one can consider the laws to be a definition of these quantities.
So are you agreeing that the postulate F=dp/dt is not formally derived?

The line of reasoning:F = dp/dt = m dv/dt can be considered a derivation in a trivial sense. But this in no way implies Newton's second law, however it is expressed, is formally derived. It is informally inferred from the set of experimental data we have.

dp/dt =m dv/dt is a derivation. Did i say Newton's second Law was derived? I don't believe I did but show me where i did and I take it back.

I normally associate formal statements with mathematical statements.

Yes if logicism is correct . But not only restricted to mathematics. The idea of a perfectly perspicuous language is one that Wittgenstein borrows from Frege and Russell and uses against them. He also rejects their theory that mathematics is an extension of logic, involving no new ideas and dealing with no new kinds of things.
http://psychology.jrank.org/pages/1884/Wittgenstein%27s-philosophy-logic-mathematics.html

But let us stick with the theology and the philosophy of science and reason as it relates to the history of the heliocentric hypothesis.

And some postulates (especially outside of physics) are difficult to formulate mathematically without losing clarity (e.g. The postulates of Darwin's theory of evolution). But if "formal" extends to beyond mathematical statements then yes.

Do you believe all formal statements can be represented in mathematical form?

Morbert

ISAW wrote: »

Because it is stated in the law itself both "change in momentum" and " force" are mentioned

Acceleration times mass isn't mentioned F=dp/dt is stating the law F= ma is derived from
dp/dt being equal to ma

The Law does not state "the product of mass times acceleration is equal to the implied force"

And as I said, yes, an equivalent statement is formally derived in a trivial sense. It is trivial because if I constructed a system of classical mechanics, but replaced F=dp/dt with F=mdv/dt as a postulate, I would end up with an equivalent system. The point relevant to this discussion is Newton's second law itself (regardless of how it is represented) is not formally derived. I.e. I was explaining to you what I meant by postulates of theories being informal inferences. Because we are discussing whether or not the postulates of a theory are "said" by a theory.

Then why did you refer to it? "There is debate over whether or not force etc. should be defined externally to Newton's laws. " If they are not internal to the theory then the postulates refer to something else which is OUTSIDE of it?

Because you brought it up as a separate, unrelated issue. Again, we were discussing whether or not the postulates of a theory are "said" by the theory. If you really think Newton's laws are controversial as postulates. We can consider the postulates of quantum mechanics instead. Ultimately, I am trying to explain to you that relativity says there is general covariance in the same way that, for example, Quantum mechanics says quantum systems (when they are not being entangled with some measurement apparatus) obey the schrodinger equation.

Well . If you are claiming that postulates are formally stated then anything formally derived from them is as you have maintained just a restatement of them.

If they are formally derived from them alone, yes. But you can derive the equations of motion of a system from Newton's postulates if you also consider the characteristics of the forces acting on the system. The equation of motion of a specific system would not simply be a restatement of newton's postulates. I.e. The ball on a spring example I mentioned earlier.

But again, I am unsure as to what this has to do with the topic at hand.

So what part of the theory is there which is NOT a formal derivation from the postulate?

The postulates themselves. But how is this related to the topic of whether or not the postulates of a theory are "said" by a theory.

in the case of newtonian mechanics as I stated it is true only for certain reference frames.

From the wiki reference I supplied
Newton's Laws hold only with respect to a certain set of frames of reference called Newtonian or inertial reference frames. Some authors interpret the first law as defining what an inertial reference frame is; from this point of view, the second law only holds when the observation is made from an inertial reference frame, and therefore the first law cannot be proved as a special case of the second.
Galili, I.; Tseitlin, M. (2003). "Newton's First Law: Text, Translations, Interpretations and Physics Education". Science & Education 12 (1): 45–73. doi:10.1023/A:1022632600805
and
http://www.lightandmatter.com/html_books/1np/ch04/ch04.html

Which culminated in two points which I raised elsewhere to which you asked "What"?:

1.The explicit concept of an inertial frame of reference was not developed until long after Newton's death.

2. In the given interpretation mass, acceleration, momentum, and (most importantly) force are assumed to be externally defined quantities. This is the most common, but not the only interpretation: one can consider the laws to be a definition of these quantities.

But what does this have to do with the topic at hand: Whether or not the postulates of a theory are "said" by the theory? This is why I am confused by your posts. Have you switched topics?

So are you agreeing that the postulate F=dp/dt is not formally derived?

dp/dt =m dv/dt is a derivation. Did i say Newton's second Law was derived? I don't believe I did but show me where i did and I take it back.

Again, you did not answer my question. But from the above, I am going to assume you agree that Newton's second law is not derived. I will assume we agree that it is postulated based on observation. Now, do you agree that Newton's second law is "said" by newtonian mechanics? I.e. Would you agree with the statement "Newtonian mechanics says F=dp/dt"?

Do you believe all formal statements can be represented in mathematical form?

I have not thought about it. I don't even know how meaningful such an endeavor would be outside any basic propositional calculus.

ISAW

Morbert wrote: »

And as I said, yes, an equivalent statement is formally derived in a trivial sense. It is trivial because if I constructed a system of classical mechanics, but replaced F=dp/dt with F=mdv/dt as a postulate, I would end up with an equivalent system.

Only because you can formally derive mdv/dt from dp/dt!

The point relevant to this discussion is Newton's second law itself (regardless of how it is represented) is not formally derived. I.e. I was explaining to you what I meant by postulates of theories being informal inferences. Because we are discussing whether or not the postulates of a theory are "said" by a theory.

Try looking at the first comment I made in this exchange with you

Actually this isnt relitivity it is one of the consequences of assumptions of cosmology.
Assumptions note!

Relativity ( and all the reference frame argument) came AFTER Galileo. Indeed newton was only born when Galileo died. The Church at the time was acting with the knowledge of science of the day. I also later explained that "relativity" is taken nowadays to mean Einsteins theory of rather then classical philosophical views of relativity of which Galileo was certainly aware.

The point being I pointed out from step one that postulates are assumptions.

Because you brought it up as a separate, unrelated issue. Again, we were discussing whether or not the postulates of a theory are "said" by the theory.

No we weren't! We were originally discussing something else. But even above what I was getting to was not whether the postulates of a theory are "said" by the theory but whether or not
1. you consider the theory to be postulates plus everything else?
2. You consider the "theory" part to be everything else?
3. If "everything else" is not trivial in the "means the same thing since it can be formally derived and expressed only in an equivalent formula" then there is no "everything else".
4. If 3 is true what hapopoened to your "informal inference" and "tacid knowledge"?

Ultimately, I am trying to explain to you that relativity says there is general covariance in the same way that, for example, Quantum mechanics says quantum systems (when they are not being entangled with some measurement apparatus) obey the schrodinger equation.)

How do you know if you can't actually measure them without causing an effect on the measurement?
But again you are saying that modern relativity has general covariance as a postulate.
Other then the trivial re expression of anything the postulates say in a formally derived sense what ELSE does relativity have?

If they are formally derived from them alone, yes. But you can derive the equations of motion of a system from Newton's postulates if you also consider the characteristics of the forces acting on the system. The equation of motion of a specific system would not simply be a restatement of newton's postulates. I.e. The ball on a spring example I mentioned earlier.

If they are derived they are no different from you "trivial" element.

But again, I am unsure as to what this has to do with the topic at hand.

Where anywhere did i claim postulates are "said by the theory" ?

The postulates themselves. But how is this related to the topic of whether or not the postulates of a theory are "said" by a theory.

No what i asked you is whether

1. the "theory of relativity" = postulates plus everything else or just "everything else"
2. Exclkuding formal derivation from the postulates what constitutes "everything else"?

But what does this have to do with the topic at hand: Whether or not the postulates of a theory are "said" by the theory? This is why I am confused by your posts. Have you switched topics?

Are you accusing me of trying to do so ? As I remember that all came from the scientific theory of the church at Galileos timer and your comment on it where you brought in relativity. I pointed out the modern theory contains additional knowledge developed after Galileo. And cosmoilogical assumptions not advanced by Galileo. I also commented on formal proofs and systems like mathematics which in Witteinsteins view are foolish to look at as logic or formal alone.

Again, you did not answer my question. But from the above, I am going to assume you agree that Newton's second law is not derived.

No. it is assumed.

I will assume we agree that it is postulated based on observation.

Maybe maybe not. Postulates dont have to be based on observation. Invewrse cube gravity for example or wormholes. But yes it is postulated.

Now, do you agree that Newton's second law is "said" by newtonian mechanics? I.e. Would you agree with the statement "Newtonian mechanics says F=dp/dt"?

The second postulate says that. the point I am saying is

1. Are the postulates part of Newtonian mechanics?
2. If so what ELSE that isnt a formal derivation from the postulates are part of "newtonian mechanics"?

Do you understand 1 and 2?

I have not thought about it.

Think about it and get back to me.

I don't even know how meaningful such an endeavor would be outside any basic propositional calculus.

So what? Meaningfull to you or to science?

Do formal systems necessitate something outside them having "meaning" or attributing a value to them?

If so then we are arriving at the destination I was hoping this exchange would get to.

Morbert

The discussion can't progress until the following is resolved.

ISAW wrote:

Morbert wrote:

Again, we were discussing whether or not the postulates of a theory are "said" by the theory.

No we weren't! We were originally discussing something else.

I said:"Relativity says the laws of physics do not change under smooth one-to-one space-time transformations."

You said:"Actually this isnt relitivity it is one of the consequences of assumptions of cosmology."

I said:"General covariance is a postulate of Einstein's theory of general relativity."

In otherwords, I was saying that, because the invariance of the laws of physics is a postulate of relativity, that it is indeed "said" by relativity. This is what we have been discussing. Do you agree or disagree that the postulates of a theory are said by a theory?

Only because you can formally derive mdv/dt from dp/dt!

And as I have said over and over and over. This derivation in no way relates to the point I was making. That Newton's second law, whether it is expressed as F=dp/dt or the equivalent F=ma, is an example of an informal inferrence/postulate. By your logic, Newton's second postulate is not a part of newtonian mechanics.

Relativity ( and all the reference frame argument) came AFTER Galileo. Indeed newton was only born when Galileo died. The Church at the time was acting with the knowledge of science of the day. I also later explained that "relativity" is taken nowadays to mean Einsteins theory of rather then classical philosophical views of relativity of which Galileo was certainly aware.

The point being I pointed out from step one that postulates are assumptions.

As an aside: Galilean relativity is not postulated by Einstein's theory of relativity. And conversely, General covariance is not postulated by any theory of Newton or Galileo.

And yes, postulates are assumptions insofar as they are not formally derived, but rather informally inferred from observation. This was never an issue. The issue is whether or not postulates of a theory are part of the theory.

But even above what I was getting to was not whether the postulates of a theory are "said" by the theory but whether or not
1. you consider the theory to be postulates plus everything else?
2. You consider the "theory" part to be everything else?
3. If "everything else" is not trivial in the "means the same thing since it can be formally derived and expressed only in an equivalent formula" then there is no "everything else".
4. If 3 is true what hapopoened to your "informal inference" and "tacid knowledge"?

I consider a theory to be a set of postulates which explain a given set of observations, and make testable predictions. I do not know what you are referring to when you say "everything else".

How do you know if you can't actually measure them without causing an effect on the measurement?

A quantum wavefunction has a special kind of amplitude with an associated probability distribution. By studying the resultant probability distributions, we can determine whether or not the time-evolution of a quantum system is described by the schrodinger equation. Modern computers also operate under the assumption that a form of the schrodinger equation is correct (the time-independent form).

But again you are saying that modern relativity has general covariance as a postulate.
Other then the trivial re expression of anything the postulates say in a formally derived sense what ELSE does relativity have?

Well if you like you can consider the predictions relativity makes as part of the theory. In the same way we can see what newtonian mechanics has to say about the motion of a ball on a spring by considering the equation of motion, we can see what relativity has to say about an arbitrary distribution of energy-momentum by considering the field equations.

<snipped bits of the post that are either reiterating the above or taking us too far afield for the time being>

The second postulate says that.

So is your answer yes or no? Let me rephrase then. Newtonian mechanics postulates "F=dp/dt". Would you say that "F=dp/dt" isn't part of newtonian mechanics?

ISAW

Morbert wrote: »

The discussion can't progress until the following is resolved.



I said:"Relativity says the laws of physics do not change under smooth one-to-one space-time transformations."

You said:"Actually this isnt relitivity it is one of the consequences of assumptions of cosmology."

I said:"General covariance is a postulate of Einstein's theory of general relativity."

In otherwords, I was saying that, because the invariance of the laws of physics

Are you saying general co variance is another way of saying ALL the laws of physics are the same everywhere?

is a postulate of relativity, that it is indeed "said" by relativity. This is what we have been discussing. Do you agree or disagree that the postulates of a theory are said by a theory?

This seems to be ther problem with this part of the discussion. whn you say "said by" do you mean "assumed in advance of anything else" or do you mean "arrived at out of the theory" It seems you mean the former.

Im just saying that the way I have oputlined it

1. there are postulates i.e. assumptions to begin with
2. There are other things in the theory
3. Other things are not just formal derivations based on the postulates i.e. not just trivial mathematical restatements of the theory as you might call them.

And as I have said over and over and over. This derivation in no way relates to the point I was making. That Newton's second law, whether it is expressed as F=dp/dt or the equivalent F=ma, is an example of an informal inferrence/postulate.

The F=ma bit isnt stated it is arrived at but it is formally arrived at.

Take something else. That light has a finite speed c in a vacuum. That is not in Newtons theory or Galileos. Assume we know c. Newton would have believed light is a particle requiring force to accelerate it to c. Using newtonian mechanics (and gravitation) we can derive the "excape velocioty" from a body . If we make that greater then c we can say the body wont admit light . I think Leplace and Mitchell did this and arrived at a historic idea of what we would call a "black hole"

By your logic, Newton's second postulate is not a part of newtonian mechanics.

Well if you call "the rest of it apart from the postulates" then it isnt no"
but the point I was making was that ther was the postuulates and "other stuff". you it appears are doing the opposite and saying there are the postulates and al the other stuff is is a "trivial" derivation from them. If it isn't then show me some other stuff.

I am asking you, excluding formal derivations from the postulates what is the "other stuff"?

As an aside: Galilean relativity is not postulated by Einstein's theory of relativity. And conversely, General covariance is not postulated by any theory of Newton or Galileo.

Back to square one. AS i poionted out the Church at the time of Galileo were dealing with "relativity" not in the Einstinean sense. Arguing about heliocentrism and geocentrism based on knowledge not known to them then is anachroinistic or at the very least parachronistic or an anatopism.

And yes, postulates are assumptions insofar as they are not formally derived, but rather informally inferred from observation. This was never an issue. The issue is whether or not postulates of a theory are part of the theory.

Let us assume they are. If so WHAT ELSE is there in the theory?

I consider a theory to be a set of postulates which explain a given set of observations, and make testable predictions. I do not know what you are referring to when you say "everything else".

So you are saying there are postulates and predictions based on formal expression of thoise postulates and nothing else in Newtonian mechanics?

Newtonian mechanics postulates "F=dp/dt". Would you say that "F=dp/dt" isn't part of newtonian mechanics?

If you define postulate as part of the theory and derivations as other stuff then F=dp/dt isn't other stuff but is part of the theory. I would say an inference based on an assumption is a theory. Is the assumption part of the inference. I would think it isn't.

Morbert

ISAW wrote: »

Are you saying general co variance is another way of saying ALL the laws of physics are the same everywhere?

General covariance is a much stronger claim. Not only are the laws of physics the same at every location, the are the same regardless of the motion of the observer with respect to objects.

This seems to be ther problem with this part of the discussion. whn you say "said by" do you mean "assumed in advance of anything else" or do you mean "arrived at out of the theory" It seems you mean the former.

Im just saying that the way I have oputlined it

1. there are postulates i.e. assumptions to begin with
2. There are other things in the theory
3. Other things are not just formal derivations based on the postulates i.e. not just trivial mathematical restatements of the theory as you might call them.

In this case I mean "claimed as an explanatory framework without formal proof or derivation".

Take something else. That light has a finite speed c in a vacuum. That is not in Newtons theory or Galileos. Assume we know c. Newton would have believed light is a particle requiring force to accelerate it to c. Using newtonian mechanics (and gravitation) we can derive the "excape velocioty" from a body . If we make that greater then c we can say the body wont admit light . I think Leplace and Mitchell did this and arrived at a historic idea of what we would call a "black hole".

Well if you call "the rest of it apart from the postulates" then it isnt no"
but the point I was making was that ther was the postuulates and "other stuff". you it appears are doing the opposite and saying there are the postulates and al the other stuff is is a "trivial" derivation from them. If it isn't then show me some other stuff.

I am asking you, excluding formal derivations from the postulates what is the "other stuff"?

Let us assume they are. If so WHAT ELSE is there in the theory?

So you are saying there are postulates and predictions based on formal expression of thoise postulates and nothing else in Newtonian mechanics?

This would be an example of a prediction. In my last example, I mentioned applying Newton's postulates to a system consisting of a ball on a string. In this example, it is a case of applying Maxwell's electromagnetism and Newton's law of gravitation to a system with sufficient mass-density. From my last post:Well if you like you can consider the predictions relativity makes as part of the theory. In the same way we can see what newtonian mechanics has to say about the motion of a ball on a spring by considering the equation of motion, we can see what relativity has to say about an arbitrary distribution of energy-momentum by considering the field equations.

So I don't have an issue with considering such things as part of the theory.

I would say an inference based on an assumption is a theory. Is the assumption part of the inference. I would think it isn't.

The problem with this is, when we run experiments, we are testing the postulates of a theory. If experimental results are consistent with the postulates, then the theory is supported. If the experimental results contradict the postulates, then the theory is falsified.

If the postulates are not part of a theory, then a theory can never be tested. A theory would be reduced to a set of implications that could not be falsified or supported any more than "1+1=2" (where 1 and 2 are real numbers) could be falsified or supported. Scientists could run tests and discover that the postulates of general relativity do not hold, but the theory of general relativity would not be falsified under this definition of theory, as only the postulates would be falsified.

Back to square one. AS i poionted out the Church at the time of Galileo were dealing with "relativity" not in the Einstinean sense. Arguing about heliocentrism and geocentrism based on knowledge not known to them then is anachroinistic or at the very least parachronistic or an anatopism.

Yes but in my post I was referring to the general principle of relativity.

ISAW

Morbert wrote: »

General covariance is a much stronger claim. Not only are the laws of physics the same at every location, the are the same regardless of the motion of the observer with respect to objects.

...

Yes but in my post I was referring to the general principle of relativity.

and my "that isn't relativity" comment was on geocentrism and heliocentrism.

It may not be Einsteinean relativity as physics understands it today but at the time of galileo they were referring to the idea that the earth was not moving and the Sun was going around it.

They didn't have the idea of co variance, reference frames, or no privileged observer.

One can not use today's concepts and claim they knew about relativity in the same way we do. One can claim there are laws of physics which operated in the same way today as they did then but that is saying something different.

Do you understand that?

Now the other side issue is to do with "does a theory contain the postulates ?" We can assume it does or we can assume it doesn't. It is just a definition. Both assumptions have implications later on. You have suggested the postulates are part of the theory. So I ask you "What else are parts of the theory?"

I want to see if you define the whole theory as postulates plus anything formally derived from them and nothing else or if you say there is something else.

If you say there is something else we are back into the same type of issue as if the postulates (or any formal derivation of them which you admit are equivalent) are not part of the theory and are viewed separately.

It would appear you think there are postulates and nothing else.

Now the Church (well I should say academics of the day at Galileo's time) based their view on reason and what they saw at the time.

ISAW

Morbert wrote: »

In this case I mean "claimed as an explanatory framework without formal proof or derivation".

...[speed of light = c and a fairly good estimate measured]

This would be an example of a prediction.

Ah but we added more assumptions!

1. that the speed of light is c and is measured near a particular speed
2. that c is constant.

a constant c isn't part of Galileo's or Newton's theory.

Morbert

ISAW wrote: »

...and my "that isn't relativity" comment was on geocentrism and heliocentrism.

It may not be Einsteinean relativity as physics understands it today but at the time of galileo they were referring to the idea that the earth was not moving and the Sun was going around it.

They didn't have the idea of co variance, reference frames, or no privileged observer.

One can not use today's concepts and claim they knew about relativity in the same way we do. One can claim there are laws of physics which operated in the same way today as they did then but that is saying something different.

Do you understand that?

Now the other side issue is to do with "does a theory contain the postulates ?"<snip>

That is the only issue we have been discussing. I have not said anything about the history of the principle of relativity.

And of course I understand. But that has nothing to do with anything I said. Furthermore "Do you understand that?" is very patronising. Especially since I am a physicist.

We can assume it does or we can assume it doesn't. It is just a definition. Both assumptions have implications later on. You have suggested the postulates are part of the theory. So I ask you "What else are parts of the theory?"

I want to see if you define the whole theory as postulates plus anything formally derived from them and nothing else or if you say there is something else.

If you say there is something else we are back into the same type of issue as if the postulates (or any formal derivation of them which you admit are equivalent) are not part of the theory and are viewed separately.

It would appear you think there are postulates and nothing else.

Now the Church (well I should say academics of the day at Galileo's time) based their view on reason and what they saw at the time.

Well the geocentrists myself and Wolfsbane were talking about are contemporary, and are well aware of relativity (which is why they hate it so much). So either way, does this mean you agree with my post to Wolfsbane?

Ah but we added more assumptions!

1. that the speed of light is c and is measured near a particular speed
2. that c is constant.

a constant c isn't part of Galileo's or Newton's theory.

Well yes. We are considering Maxwell's theory of electromagnetism, which says the speed of light in a vacuum is a constant c, and applying it to a specific system. I said I don't take issue with this.

"It is a case of applying Maxwell's electromagnetism and Newton's law of gravitation to a system with sufficient mass-density."

ISAW

Morbert wrote: »

That is the only issue we have been discussing. I have not said anything about the history of the principle of relativity.

And of course I understand. But that has nothing to do with anything I said. Furthermore "Do you understand that?" is very patronising. Especially since I am a physicist.

Well I have to ask since i don't know which actual point you are addressing.
Also I think Socrates suggested that knowing you don't know is the beginning of wisdom.
Also, please look up "argument from authority".
Just because you are a physicist does not mean there may be things about physics or science about which you may have an opinion which is actually wrong.

For example it appears the "physicists" of Galileo's day ( or natural philosophers as they were called as was Newton by the way who studied to be a priest) were indeed wrong about absolute motion.

when you say you are a physicist by the way what do you mean? Do you get paid to do research? Do you teach physics ? Do you have a PhD or similar in physics?
.
I'll accept your experience with the solution to equations with second derivatives or tensors is no doubt germane to the topic of general Einsteinean relativity.

However, the points I made were related more to the history and philosophy of science and mathematics rather than the actual physics and mathematics involved

Well the geocentrists myself and Wolfsbane were talking about are contemporary, and are well aware of relativity (which is why they hate it so much). So either way, does this mean you agree with my post to Wolfsbane?

Don't know which actual part? You are referring to post 33?
I didnt look at the reference Wolfsbane posted.

you comment "They are not considering relativity at all. In fact, relativity would have to be wrong for geocentricism to be right"

I took it to be a comment on the physicists of the day commenting on Galileo's views. That there would have to be no relative motion for the sun to be going round the Earth. But as it happens given the measurements of the day the Tychonic system could not be disproved. In that system the sun goes round the Earth. Galileo's "on two world systems Copernican and Aristotelian" didn't consider this.

Galileo develops physics much more in a later (and I would contend greater) work Called "Two new Sciences" but as I say that is later.

There are a lot of myths about the Galileo history.
Now-Do I think modern relativity is not proper science and is all wrong ?No I don't.

Well yes. We are considering Maxwell's theory of electromagnetism, which says the speed of light in a vacuum is a constant c, and applying it to a specific system. I said I don't take issue with this.

"It is a case of applying Maxwell's electromagnetism and Newton's law of gravitation to a system with sufficient mass-density."

The point I am trying to make I guess is that I want you to assume you are at Galileo's trial. Making points about Maxwell or Newton is a bit like say re running the Irish Traty debate ion the Dail and Collons or Dev saying something like . "But if you dont agree with me that could mean that one day Ireland will be split into two parts and Irish people terrorise each other " and the other saying "a yeah but maybe later the two sides could
come together in Belfast and have an agreement to a constitutional settlement" and all sorts of "what if ..."statements based on our understanding of history today and not on their understanding at that time.

Based on the knowledge of the day statements like "Church was right and Galileo wrong" isn't such a silly statement. And I say that even knowing that Galileo was a genius far superior as a scientist to those he faced.

Morbert

ISAW wrote: »

Well I have to ask since i don't know which actual point you are addressing.
Also I think Socrates suggested that knowing you don't know is the beginning of wisdom.
Also, please look up "argument from authority".
Just because you are a physicist does not mean there may be things about physics or science about which you may have an opinion which is actually wrong.

I did not make an argument from authority so I have no idea why you are bringing it up?

<stuff about geocentrists>

Wolfsbane wanted to know how Geocentirsts employ relativity in their argument. I said they don't and in fact they reject it due to what it says about the form of physical laws. You said "actually this isn't relativity." Now that you understand we were talking about contemporary geocentrists, do you have any issues with my post to wolfsbane?

when you say you are a physicist by the way what do you mean? Do you get paid to do research? Do you teach physics ? Do you have a PhD or similar in physics?

Yes I get paid to do research. I have a Bachelors, Masters, and am finishing a PhD. Though it is in quantum mechanics, and does not employ any relativity other than what is already implicitly built into quantum field theory

ISAW

Morbert wrote: »

I did not make an argument from authority so I have no idea why you are bringing it up?

And of course I understand. But that has nothing to do with anything I said. Furthermore "Do you understand that?" is very patronising. Especially since I am a physicist.

Of course I understand ...I am a physicist

http://skepticwiki.org/index.php/Argument_from_Authority

'Argument from Authority is an informal logical fallacy, formally known as argumentum ad verecundium, where an participant argues that a belief is correct because the person making the argument is an authority. The most general structure of this argument runs something like the following:

1. Person A claims that P
2. Person A is a respected scientist or other authority
3. Therefore, P is true.

This is a fallacy because the truth or falsity of the claim is not necessarily related to the personal qualities of the claimant.

Wolfsbane wanted to know how Geocentirsts employ relativity in their argument. I said they don't and in fact they reject it due to what it says about the form of physical laws.

You refer to Einstinean relativity. the site he linked seems also to mention historic philosophical relativity, which though related, is a different entity.

You said "actually this isn't relativity." Now that you understand we were talking about contemporary geocentrists, do you have any issues with my post to wolfsbane?

I didn't look at the site. I have now and it appears it does refer to historic relativity. Just what part of their argument on Galileowaswrong do you claim is not in falsified by modern relativity? I am prepared to accept your argument with respect to modern relativity.

Yes I get paid to do research. I have a Bachelors, Masters, and am finishing a PhD. Though it is in quantum mechanics, and does not employ any relativity other than what is already implicitly built into quantum field theory

Modern relativity then. I am also prepared to accept your level training an education do attest to you being a "physicist". But I assume when you mention "relativity" you refer only to the 20th century theory in physics as developed by Einstein and others?

That may discount many of the arguments raised by the website but it doesnt discount that though Galileos theory was right the measurements of the day couldnt conform that and there were alternative theories at the time to Heliocentrism which could not be falsified. that is the point I am making.

Morbert

ISAW wrote: »

http://skepticwiki.org/index.php/Argument_from_Authority

'Argument from Authority is an informal logical fallacy, formally known as argumentum ad verecundium, where an participant argues that a belief is correct because the person making the argument is an authority. The most general structure of this argument runs something like the following:

1. Person A claims that P
2. Person A is a respected scientist or other authority
3. Therefore, P is true.

This is a fallacy because the truth or falsity of the claim is not necessarily related to the personal qualities of the claimant.

This makes no sense to me. I said I did not make an argument from authority. You posted a description of an argument from authority, but made no effort to actually explain how I made an argument from authority.

You refer to Einstinean relativity. the site he linked seems also to mention historic philosophical relativity, which though related, is a different entity.

I didn't look at the site. I have now and it appears it does refer to historic relativity. Just what part of their argument on Galileowaswrong do you claim is not in falsified by modern relativity? I am prepared to accept your argument with respect to modern relativity.

From Wolfsbane's link, and its related site, geocentirsm.com:

"the disturbing possibility that part of modern cosmology and physics, including Relativity Theory, has been invented out of “whole cloth” precisely to avoid the philosophical implications of a universe with a motionless earth at the center."

"Rather science becomes more complicated to reconcile the observations with the undemonstrated assertion that the earth is moving and not in the center. Now we must accept that the universe is a 4-dimensional hypercube or doughnut (in order to escape the possibility that we are at center) and that objects (and clocks) shrink in the direction of travel (to escape the interferometric evidence that we are not circling the sun at 30 km/second), etc."

"science has disregarded the possibility of redshifts indicating that (as we observe) we actually are in the center. As Hubble indicated, instead, science has adopted general relativity to "escape" the possibilty."

"There is no need for dependence on any formulation from general relativity."

It is obvious that they are talking about relativity in a modern scientific context.

That may discount many of the arguments raised by the website but it doesnt discount that though Galileos theory was right the measurements of the day couldnt conform that and there were alternative theories at the time to Heliocentrism which could not be falsified. that is the point I am making.

That was not the point you were making. The point you were making was that what I said "wasn't relativity".

ISAW

Morbert wrote: »

This makes no sense to me. I did not make an argument from authority. You posted a description of an argument from authority, but made no effort to actually explain how I made an argument from authority.

Did you notice the words before the expaination

"Of course I understand ...I am a physicist "

1. Morbert claims that he understands something.
2. Morbert asserts he is a respected physicist.
3. Therefore, what Morbert claims based on this authority is true.

"Of course I understand ...I am a physicist "

From Wolfsbane's link, and its related site, geocentirsm.com:
snip

That was not the point you were making. The point you were making was that what I said "wasn't relativity".

The above site has two seperate volumes

1. The scientific case for geocentrism - you apparently argue this is wrong based on modern relativity. I don't disagree with that but I would add that modern cosmology can be viewed as if anywhere is the center of the universe due to relativity. I think they may be taking "earth is at the center" as if that is an extrodinary claim. If everywhere is as if it was at the centre then it is not such a claim.

2. the historic case. I argue the point that in terms of history Galileo could not show geocentrism true based on measurement at that time.

Morbert

ISAW wrote: »

Did you notice the words before the expaination

"Of course I understand ...I am a physicist "

1. Morbert claims that he understands something.
2. Morbert asserts he is a respected physicist.
3. Therefore, what Morbert claims based on this authority is true.

"Of course I understand ...I am a physicist "

[edit]-to clarify

Yes I noticed the words. What about them? Where did I make an argument from authority?

I said:"And of course I understand. But that has nothing to do with anything I said. Furthermore "Do you understand that?" is very patronising. Especially since I am a physicist." I.e. You can assume I understand of the development of classical mechanics via Galileo, Newton, and Einstein. A development we both agree on.

The above site has two seperate volumes

1. The scientific case for geocentrism - you apparently argue this is wrong based on modern relativity. I don't disagree with that but I would add that modern cosmology can be viewed as if anywhere is the center of the universe due to relativity. I think they may be taking "earth is at the center" as if that is an extrodinary claim. If everywhere is as if it was at the centre then it is not such a claim.

2. the historic case. I argue the point that in terms of history Galileo could not show geocentrism true based on measurement at that time.

This particular group of geocentrists assert that the reference frame with earth stationary and at the centre is a unique reference frame, and that relativity is just a contrived attempt to explain away the apparent uniqueness.

ISAW

Morbert wrote: »

[edit]-to clarify

Yes I noticed the words. What about them? Where did I make an argument from authority?

I said:"And of course I understand. But that has nothing to do with anything I said. Furthermore "Do you understand that?" is very patronising. Especially since I am a physicist." I.e. You can assume I understand of the development of classical mechanics via Galileo, Newton, and Einstein. A development we both agree on.

But we cant assume that because you are a physicist you are conversant with the history and philosophy of science or the context of Galileo's inquisitions.

Here is what I stated:

It may not be Einsteinean relativity as physics understands it today but at the time of galileo they were referring to the idea that the earth was not moving and the Sun was going around it.

They didn't have the idea of co variance, reference frames, or no privileged observer.

One can not use today's concepts and claim they knew about relativity in the same way we do. One can claim there are laws of physics which operated in the same way today as they did then but that is saying something different.

I was in no way trying to patronise you by asking do you understand the above. It was more in the line of "do you see where I am coming from?" If you felt insulted by that I apologise it certainly was not intentional.

This particular group of geocentrists assert that the reference frame with earth stationary and at the center is a unique reference frame, and that relativity is just a contrived attempt to explain away the apparent uniqueness.

And from the point of view of modern science they would be wrong. Modern science being not just another view but the best way we have of explaining the world to date.

However from an anthropocentric view Earth is special and unique even if only because we are here.

Morbert

ISAW wrote: »

But we cant assume that because you are a physicist you are conversant with the history and philosophy of science or the context of Galileo's inquisitions.

Here is what I stated:

I was in no way trying to patronise you by asking do you understand the above. It was more in the line of "do you see where I am coming from?" If you felt insulted by that I apologise it certainly was not intentional.

Ok, but just so long as it's clear that I was not making an argument from authority. I will admit that it might not be wise to assume that people involved in physics necessarily know the history.

And from the point of view of modern science they would be wrong. Modern science being not just another view but the best way we have of explaining the world to date.

However from an anthropocentric view Earth is special and unique even if only because we are here.

Does this mean you agree with what I said to wolfsbane?

ISAW

Morbert wrote: »

Ok, but just so long as it's clear that I was not making an argument from authority. I will admit that it might not be wise to assume that people involved in physics necessarily know the history.



Does this mean you agree with what I said to wolfsbane?

AS regards modern relativity I don't disagree with you. Maybne i am not conversant enough to understand. I think I probably am. If you think I am at a level to I know enough about the field then I agree with respect to modern theory. I don't agree with you with respect to the same point about Galileo in the context of history when modern theories were not known.

I have a lot of posts ion the "science and religion" thread so will give this one a rest.