[watsisname]

Are all points on the surface of a non-rotating neutron star the same distance from the center (to a good approximation) only if something is observing it?  Is there ever a time when it just decides to ignore the laws of physics and become angular? 

Do objects follow the laws that our descendents wrote in a paper, otherwise they go to jail or smth?

I assert that the laws of physics as we know them do not suddenly cease to apply if nobody is looking.  I like your "break the laws of physics --> go to space jail" idea though.  Maybe that's what black holes are.

But I'm diggressing, flame me at will.

No thanks, I'm here for rational discussion.

Back to your point, no I'm not saying that things stop existing the moment you close your eyes. I'm saying that they don't care what you call them or what you decide they should do while calling it a "law". Is earth spherical, or not? Are the atoms of the surface (And what exactly constitutes the surface?) of the neutron star (and where is this "non-rotating" neutron star exactly located, apart from inside your own abstractions?) exactly placed in a spherical position?

No, you yourself agree they are not. They could as well be defined fractally, it depends upon what we want to study, to inform, etc.

I think you have missed the parts of my posts (both of them) where I said "to a good approximation" or words along those lines.  "To good approximation" can also be quantified.  I can state that an object's surface deviates from a perfect sphere by less than 0.1% and I would be making a statement that is based on reality, not perception.

I agreed with you that perfect spheres do not exist in the real world because there are always irregularities at small scales.  That's why I gave the event horizon example, since that's the closest thing to a perfect sphere you'll ever be likely to find in nature.

Abstract concepts that were invented by humans are very useful to categorize stuff that we see out there. I agree that if you choose to categorize your object as a "cube" then you are speaking english correctly and you are conveying useful information to me.

Concepts invented by humans and useful to categorize, yes, but they are still saying something accurate about objective reality.  My cube is in fact a cube to within whatever error bars are required?

Topology is an abstract concept that has certain needs that you can't guarantee on your objects.

You can't guarantee that the surface of the gravity B probe's gyroscopes differ from perfect spheres by less than 50 atoms of thickness?

I'm not saying that math and physics aren't useful. I'm saying they are constructs, they are not reality. They are models. Models do not "exist out there" as "objects".

This is an ancient mistake, like saying that things "exist in themselves".

-Concepts like "length" and "orthogonality" are not models, they are mathematical truths.
-Nobody is saying that perfect shapes exist in nature.
-I am saying that surfaces/boundaries of objects are quantifiable and that said quantification is a statement about objective reality, something that is true with or without human presence.

I have a question for you. Does an orbit of a planet "really exists" outside the human mind?

The trajectory of an object through space over a time interval is not the same as the boundary of an object, so I'm afraid I don't see the relevance of your question.  I'd say it "really exists" only as much as world-lines in 4D space-time "really exist".

Counter-question:  Is it an empirical truth that Venus' orbit around the sun traces out a path that differs from a perfect circle by less than 1%?  Or is that subjective, up for interpretation?
(Venus' orbital eccentricity is currently ~0.0067)


edit: 

[awkwardly intimate image of a cube trying to make a point]

hey look, he called it a cube!  my work here is done.

[Luis Dias]

I think you have missed the parts of my posts (both of them) where I said "to a good approximation" or words along those lines.  "To good approximation" can also be quantified.  I can state that an object's surface deviates from a perfect sphere by less than 0.1% and I would be making a statement that is based on reality, not perception.

Yes, but it isn't reality. It is your own model. Atoms that are aligned gravitationally within an apparent sphere do not care what you call them.

I agreed with you that perfect spheres do not exist in the real world because there are always irregularities at small scales.  That's why I gave the event horizon example, since that's the closest thing to a perfect sphere you'll ever be likely to find in nature.

It may be the "closest", but it is far from "perfect". They apparently have hairs, and if they rotate (which is pretty much a guarantee), then you lose the perfection of the sphere right there.

Spheres are platonic ideals. Reality is not ideal, it is for real, ar ar ar.

Concepts invented by humans and useful to categorize, yes, but they are still saying something accurate about objective reality.  My cube is in fact a cube to within whatever error bars are required?

"Error bars" and "accurate" are also human concepts . They can also mislead you severely, and they themselves are prone to human point of view. There is no absolute truths, and that's not an absolute truth either .

You can't guarantee that the surface of the gravity B probe's gyroscopes differ from perfect spheres by less than 50 atoms of thickness?

For your purposes? Sure you can. You just can't say that it what it *is* happening in real reality, for that may or may not be the case. Something may have happened while you weren't looking, etc. .

-Concepts like "length" and "orthogonality" are not models, they are mathematical truths.

Mathematical truths are nothing more than useful human-made tautologies.

-Nobody is saying that perfect shapes exist in nature.

Therefore, "shapes" do not exist in nature, but they are useful for us to categorize what we see into different columns in tables .

-I am saying that surfaces/boundaries of objects are quantifiable and that said quantification is a statement about objective reality, something that is true with or without human presence.

How can something be quantified without a sentient being making the quantification? I'd guess that the audience is smart enough to realise that even quantum mechanics is a theory about what is seen by an observer, and what kind of predictions we can calculate between observations. Physics is not about what happens in "real reality", but about observational predictions.

The trajectory of an object through space over a time interval is not the same as the boundary of an object, so I'm afraid I don't see the relevance of your question.  I'd say it "really exists" only as much as world-lines in 4D space-time "really exist".

The boundary of an object depends upon the interested point of view. Is the boundary of venus its upper atmosphere, or its ground? Is the boundary of the sun its convective layer or its corona? Or is it its solar system? Is it its solar wind bubble? It depends of what we are interested in.

Counter-question:  Is it an empirical truth that Venus' orbit around the sun traces out a path that differs from a perfect circle by less than 1%?  Or is that subjective, up for interpretation?
(Venus' orbital eccentricity is currently ~0.0067)

It is an empirical truth that it is so, currently. You use the word empirical correctly .

[General Battuta]

Math is probably the only damn thing in the world that can be said to exist with absolute objectivity, 'out there'. It holds across species and even across conceivable universes. It's probably the very foundation of not just reality but all possible realities.

It's also immaterial to the topic at hand. I cannot conceive of a way in which a species would fail to mathematically describe the event horizon of a black hole. All species which encounter a black hole and describe its event horizon will do so using the same mathematics. The same cannot be said of the human perception of color. They are intrinsically different.

[watsisname]

I think you have missed the parts of my posts (both of them) where I said "to a good approximation" or words along those lines.  "To good approximation" can also be quantified.  I can state that an object's surface deviates from a perfect sphere by less than 0.1% and I would be making a statement that is based on reality, not perception.

Yes, but it isn't reality. It is your own model. Atoms that are aligned gravitationally within an apparent sphere do not care what you call them.

No, the arrangement of the atoms is reality.  The statement that the geometry of the surface deviates from a perfect sphere by less than 0.1% is a statement about that reality.  Maybe that is our disagreement afterall... I consider the description of that arrangement to be a shape, and you don't because you only consider "pure" shapes to be shapes, which obviously no material entity in nature will ever match.  If that's the case then it's mainly just a difference of definition.

I agreed with you that perfect spheres do not exist in the real world because there are always irregularities at small scales.  That's why I gave the event horizon example, since that's the closest thing to a perfect sphere you'll ever be likely to find in nature.

It may be the "closest", but it is far from "perfect". They apparently have hairs, and if they rotate (which is pretty much a guarantee), then you lose the perfection of the sphere right there.

Spheres are platonic ideals. Reality is not ideal, it is for real, ar ar ar.

I know all that already, and that's not the point.  The shape of the black holes event horizon is the closest thing to a perfect sphere that you're likely to find in nature.
And I explicitly said "non-rotating" black hole in the first post, though actually on further reading it seems that rotation does not affect the sphericity of the event horizon.  It only affects the ergosphere.  That's not really relevant though because I already know and said that there are no perfect spheres in nature.

Concepts invented by humans and useful to categorize, yes, but they are still saying something accurate about objective reality.  My cube is in fact a cube to within whatever error bars are required?

"Error bars" and "accurate" are also human concepts . They can also mislead you severely, and they themselves are prone to human point of view. There is no absolute truths, and that's not an absolute truth either .

Does that mean that my cube, in 'real reality', might be closer to a perfect sphere than a perfect cube because our human perspectives and error bars are misleading?

Topology is an abstract concept that has certain needs that you can't guarantee on your objects.

You can't guarantee that the surface of the gravity B probe's gyroscopes differ from perfect spheres by less than 50 atoms of thickness?

For your purposes? Sure you can.

No, I do not mean just for my purposes.  I mean in objective reality.  Is it within 50 atoms of thickness of a perfect sphere, or not?

You just can't say that it what it *is* happening in real reality, for that may or may not be the case. Something may have happened while you weren't looking, etc. .

Do you believe giant pink elephants suddenly appear on the moon in 'real reality' when nobody is looking?

I am saying that surfaces/boundaries of objects are quantifiable and that said quantification is a statement about objective reality, something that is true with or without human presence.

How can something be quantified without a sentient being making the quantification?

Sorry, my writing wasn't very clear.  I mean that the surface of an object is what it is, with or without the presence of a sentient being.  All intelligent sentient beings (assuming of equal or greater dimension to the object in question) can examine the object and quantify the geometry of the surface.  Some might have more numerical accuracy than others, like one might say "I can tell that this is spherical to within 1%, while another might have better precision and be able to say "this is spherical to within 0.1%", but all of them agree, and all of them are statements about an objective reality -- the geometry (shape) of the object's surface.

Are we able to agree on at least this much?

Counter-question:  Is it an empirical truth that Venus' orbit around the sun traces out a path that differs from a perfect circle by less than 1%?  Or is that subjective, up for interpretation?
(Venus' orbital eccentricity is currently ~0.0067)

It is an empirical truth that it is so, currently. You use the word empirical correctly .

Excellent.  Now say humanity never took an interest in astronomy and we never bothered to determine the orbit of Venus.  Would Venus' orbit then be different from that ellipse with e~0.0067?

[Luis Dias]

Math is probably the only damn thing in the world that can be said to exist with absolute objectivity, 'out there'. It holds across species and even across conceivable universes. It's probably the very foundation of not just reality but all possible realities.

I'm sure you are about to make a proof of this idiocy.

It's also immaterial to the topic at hand. I cannot conceive of a way in which a species would fail to mathematically describe the event horizon of a black hole. All species which encounter a black hole and describe its event horizon will do so using the same mathematics. The same cannot be said of the human perception of color. They are intrinsically different.

So the absoluteliness of mathematics is dependent upon the limitations of your imagination? And that's enough for someone to state absolutes? Pretty pathetic.

[Luis Dias]

No, the arrangement of the atoms is reality.  The statement that the geometry of the surface deviates from a perfect sphere by less than 0.1% is a statement about that reality.  Maybe that is our disagreement afterall... I consider the description of that arrangement to be a shape, and you don't because you only consider "pure" shapes to be shapes, which obviously no material entity in nature will ever match.  If that's the case then it's mainly just a difference of definition.

An arrangement is a human abstraction that is completely analogous, if not synonimous with "shape". So you just substituted words there. "Arrangements" are as real as the Earth's orbit.

And I explicitly said "non-rotating" black hole in the first post

I know, but the issue is that you were almost saying that ideals exist in reality because if we consider an ideal non rotating black hole, then its shape is ideal. Ok, but then you are making a tautology of ideals, aren't you? I also know that you didn't go so far.

Does that mean that my cube, in 'real reality', might be closer to a perfect sphere than a perfect cube because our human perspectives and error bars are misleading?

I'm saying that you cannot say anything about "real reality" at all, and it doesn't matter at all. Stick with empiricism, which is what we do best. Empirical reality is what matters. "Real reality" is a metaphysical entity, where spheres could be cubes and you could just be under an astronomical misaprehension. Perhaps God is a prankster . You can't know these things.

No, I do not mean just for my purposes.  I mean in objective reality.  Is it within 50 atoms of thickness of a perfect sphere, or not?

I have no idea, nor do I have any slight interest in knowing these transcendent truths.

Do you believe giant pink elephants suddenly appear on the moon in 'real reality' when nobody is looking?

I believe you can't make a statement about it. Most people do anyway, and they get along fine, so it's not a big deal.

Sorry, my writing wasn't very clear.  I mean that the surface of an object is what it is, with or without the presence of a sentient being.

Yeah, but there is no "surface" if there isn't the concept of "surface", which is impossible to exist without someone inventing it. Mathematics is a language. It doesn't exist if there are no speakers. Things are what they are and the text is the text is the text.

All intelligent sentient beings (assuming of equal or greater dimension to the object in question) can examine the object and quantify the geometry of the surface.  Some might have more numerical accuracy than others, like one might say "I can tell that this is spherical to within 1%, while another might have better precision and be able to say "this is spherical to within 0.1%", but all of them agree, and all of them are statements about an objective reality -- the geometry (shape) of the object's surface.

Are we able to agree on at least this much?

We can agree that there is an astonishing agreement in our inter-subjective analysis of our models, and that such phenomena is almost a miracle and should be praised.

I won't agree that this is outside human minds. It isn't solipsistic either. Let me clarify a bit: this distinction between "objective" and "subjective" in the sense that there are "truths" that are either one or the other is completely abhorrent except if you are a dualist. A dualist will believe that abstractions like mathematics "really do exist" in its own plane of existence, more or less like Plato defined, slightly apart from the material world which is imperfect and dull and noisy and chaotic. A dualist will think that objects exist "apart" from their own "soul" because souls are immaterial, therefore the distinction is necessary.

Problem is that if you aren't a dualist, this distinction is neither necessary nor consistent. Your own mind is an object as well inside the universe.

Excellent.  Now say humanity never took an interest in astronomy and we never bothered to determine the orbit of Venus.  Would Venus' orbit then be different from that ellipse with e~0.0067?

This question is only possible because we have an interest in astronomy and are considering an alternative universe. But the conversation itself is taking place in our universe, giving rise to the apparent paradox. If there wasn't *ever* an interest in astronomy so that no one could have ever done such measurement, the sentence would be unscientific and probably untrue, given the odds. No rational person would trust such a sentence.

[Mustang19]

It's also immaterial to the topic at hand. I cannot conceive of a way in which a species would fail to mathematically describe the event horizon of a black hole. All species which encounter a black hole and describe its event horizon will do so using the same mathematics. The same cannot be said of the human perception of color. They are intrinsically different.

All species which encounter a human brain and describe its physical processes will do so using the same mathematics. Its just a matter them being more likely to come across a black hole.

[General Battuta]

That's fine and dandy but how is it relevant to the question of whether or not there is a difference between shape and color in terms of existing only in our heads?

Color only exists if you model a human brain. Shape exists as a fundamental element of mathematics, which is universal and objective. I'm not arguing that you can't describe color mathematically but it's clearly on an entirely different level from shape, one that requires the creation of a (more or less) arbitrary intermediary.

[StarSlayer]

Pray to math, for she is an impartial god. 

[Mustang19]

Shape exists as a fundamental element of mathematics

It depends on what you mean by "fundamental" as one must first remove location, scale and rotational effects to recognize shape. Otherwise the visual reasoning (colliculus and other areas) and mathematical reasoning (intraparietal sulcus) parts of our brain would be redundant to have together.

[Luis Dias]

Pray to math, for she is an impartial god. 

Yeah, the faith is strong with that one. I'm sure he will square Godel's incompleteness theorem with that bull**** about maths being all perfect, all independent from us stupid humans, universal and just godlike insanely good.

[Mustang19]

Mathematical ability was important to human survival when we were evolving. The humans that didn't have math-brains died out.

That's why the math we do is the math that works.

[Snail]

ITT: Maths = secular religion

[General Battuta]

I'm sure he will square Godel's incompleteness theorem with that bull**** about maths being all perfect, all independent from us stupid humans, universal and just godlike insanely good.

Watching people who don't understand Godel muck about with Godel is almost as good as watching English majors use quantum mechanics.

[Luis Dias]

I'm sure he will square Godel's incompleteness theorem with that bull**** about maths being all perfect, all independent from us stupid humans, universal and just godlike insanely good.

Watching people who don't understand Godel muck about with Godel is almost as good as watching English majors use quantum mechanics.

Project much?

[Mustang19]

No one here is actually a physicist except Hera.

[Mika]

No one here is actually a physicist except Hera.

That would be incorrect. There are several other physicists on this forum, including me.

[Mustang19]

Then why do you never talk about physics in these stupid threads?

[MP-Ryan]

Also, my understanding is that the retina itself does some amount of preprocessing of the visual data, but can't exactly recall what it was. I need to dig up more of this on tomorrow at work. Would you recall something on this MP-Ryan? At this moment I'm not sure at which point even the residual distortion of the image is removed, I would guess it is visual cortex but then again, visual sensory stuff is outside my area of research (though I do instruments for that purpose too).

I mentioned this a few pages back, and it was buried deep in an explanation.  Basically, photoreceptors respond to a range of wavelengths along absorption curves.  Areas of the retinae then map directly to discrete areas of the primary visual cortex.  It's the overlapping absorption curves that produce pre-processing; different light inputs can cheat to create the same perception of light to the organism because the conditions have no evolutionary meaning.  The brain cheats - we don't see light differences that are irrelevant to us because of the way photoreceptors operate.  Photoreceptors also send lateral signals, and can perform lateral inhibition on their neighbors, depending on the sequence of firing and the number of the same type firing in a discrete visual field [the retina sends data to the brain via visual fields, rather than based on the firing on individual photoreceptors].

This is probably enormously confusing; this is where I'd recommend Googling it =)  Actually, this is kind of a good read:  http://serendip.brynmawr.edu/bb/latinhib.html

[Mika]

Then why do you never talk about physics in these stupid threads?

But I do when I see something interesting. I just don't have the time Herra does. And there are some topics I wont touch.

I mentioned this a few pages back, and it was buried deep in an explanation.  Basically, photoreceptors respond to a range of wavelengths along absorption curves.  Areas of the retinae then map directly to discrete areas of the primary visual cortex.  It's the overlapping absorption curves that produce pre-processing; different light inputs can cheat to create the same perception of light to the organism because the conditions have no evolutionary meaning.  The brain cheats - we don't see light differences that are irrelevant to us because of the way photoreceptors operate.  Photoreceptors also send lateral signals, and can perform lateral inhibition on their neighbors, depending on the sequence of firing and the number of the same type firing in a discrete visual field [the retina sends data to the brain via visual fields, rather than based on the firing on individual photoreceptors].

This is probably enormously confusing; this is where I'd recommend Googling it =)  Actually, this is kind of a good read:  http://serendip.brynmawr.edu/bb/latinhib.html

Ah. It makes actually perfect sense and is nicely condensed. I recall human is more sensitive in detecting horizontal movement against vertical movement, but if this distinction happens within the retina I'm not sure. Human vision seems to perform poorly when only detection of angular magnification is conserned; when an object enlarges at a noticeable rate, that is usually too late to avoid anything if caught unguard.

Another interesting thing happens with eyepieces with large fields of view. Zeiss once manufactured an eye-piece with an apparent field of view exceeding 120 degrees. In the testing phase, it turned out that this didn't work as well as thought. When observing large angles, eye swivels in the socket and then there will be a displacement between the exit pupil of the eye-piece and the pupil of the eye.