What Distance Must An Object Be For Its Appearance To Equal Its Real Size?

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  3. » What Distance Must An Object Be For Its Appearance To Equal Its Real Size?

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Reply Fri 12 Feb, 2010 06:49 pm
At what distance must an object be from a perceiver in order for its appearance to equal its real size?

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mister kitten
 
Reply Fri 12 Feb, 2010 06:56 pm
@Pythagorean,
Solids, liquids, or gases?
 
Pythagorean
 
Reply Fri 12 Feb, 2010 07:06 pm
@mister kitten,
In normal usage we don't refer to gasses themselves as objects. The same holds true with liquids. When we refer to a liquid we usually refer to a quantity such as a gallon, or a quart etc.

I personally would recommend for the sake of philosophical discussion that we keep to simple everday solid objects, at least to start out.

How about using as an object a coin such as a silver dollar??

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mister kitten
 
Reply Fri 12 Feb, 2010 07:19 pm
@Pythagorean,
We can't perceive an object's real size, because we cannot occupy the same place as the object.
 
Scottydamion
 
Reply Fri 12 Feb, 2010 08:50 pm
@mister kitten,
mister kitten;127704 wrote:
We can't perceive an object's real size, because we cannot occupy the same place as the object.


Agreed. All objects have a size, but we make that size relative to ourselves. To come close to the perception of an object's size is to measure it so that we have an agreed frame of reference.
 
Pythagorean
 
Reply Fri 12 Feb, 2010 09:19 pm
@Scottydamion,
Scottydamion;127735 wrote:
Agreed. All objects have a size, but we make that size relative to ourselves. To come close to the perception of an object's size is to measure it so that we have an agreed frame of reference.


Why would occupying the same space as the object reveal its true size?

And what is the agreed frame of reference? Do you mean that its real size is subjective?

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Jebediah
 
Reply Fri 12 Feb, 2010 10:38 pm
@Pythagorean,
Pythagorean;127695 wrote:
At what distance must an object be from a perceiver in order for its appearance to equal its real size?

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Our perception is generally pretty good at that. But it's a mix of things like:

1) our knowledge of what the object is and what size it should be
2) our knowledge of the surrounding objects
3) feedback from the muscles in our eyes telling us the angle at which they are focused
4) various other depth cues.

For the most part we perceive a quarter as quarter size at any distance. Not perfectly of course.

Well, that's the cognitive perspective. I'm not sure what you would be getting at with the philosophical angle.
 
Pythagorean
 
Reply Fri 12 Feb, 2010 11:30 pm
@Jebediah,
Jebediah;127758 wrote:
Our perception is generally pretty good at that. But it's a mix of things like:

1) our knowledge of what the object is and what size it should be
2) our knowledge of the surrounding objects
3) feedback from the muscles in our eyes telling us the angle at which they are focused
4) various other depth cues.

For the most part we perceive a quarter as quarter size at any distance. Not perfectly of course.

Well, that's the cognitive perspective. I'm not sure what you would be getting at with the philosophical angle.



If you hold the quarter one half inch away from your right eye (and close your left eye) the quarter appears a certain size (let's say at this distance the quarter appears "large").

And if you stand the quarter up on its side and walk approximately 15 feet away and turn around to look at the quarter it appears a certain size (let us say at this distance the quarter appears "small").

So which of these two perspectives reveals the real size of the quarter?
 
mister kitten
 
Reply Fri 12 Feb, 2010 11:45 pm
@Pythagorean,
Pythagorean;127767 wrote:


So which of these two perspectives reveals the real size of the quarter?


Neither perspective reveals the real size of the quarter.
 
Jebediah
 
Reply Fri 12 Feb, 2010 11:56 pm
@Pythagorean,
Pythagorean;127767 wrote:
If you hold the quarter one half inch away from your right eye (and close your left eye) the quarter appears a certain size (let's say at this distance the quarter appears "large").

And if you stand the quarter up on its side and walk approximately 15 feet away and turn around to look at the quarter it appears a certain size (let us say at this distance the quarter appears "small").

So which of these two perspectives reveals the real size of the quarter?


Hmm, but I'm not sure it does. It takes up more of our visual field when up close to our eye, but I think it still looks small. And the moon still looks big to me.

The stars look tiny though, even though they are giant. So just viewing something can't reveal it's true size. We need more information.
 
Scottydamion
 
Reply Sat 13 Feb, 2010 12:15 am
@Jebediah,
Jebediah;127773 wrote:
Hmm, but I'm not sure it does. It takes up more of our visual field when up close to our eye, but I think it still looks small. And the moon still looks big to me.

The stars look tiny though, even though they are giant. So just viewing something can't reveal it's true size. We need more information.


Exactly, and since our means of measurement are based on our relative size to things around us, the "real" size of a quarter seems somewhat of a silly question. It is the relative size of the quarter that we see. No matter what you consider a "real" size, you are still bound to relate it to something else to make your point, or to relate it to your own perceptions (which in turn are there by relating the size of objects to the depth of one's field of vision).
 
Pythagorean
 
Reply Sat 13 Feb, 2010 12:38 am
@Scottydamion,
mister kitten;127769 wrote:
Neither perspective reveals the real size of the quarter.


Correct.

Jebediah;127773 wrote:


The stars look tiny though, even though they are giant. So just viewing something can't reveal it's true size. We need more information.


Correct. Just viewing something can't reveal it's true size.

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I'd like to ask what I think is a related question: If we hold the quarter up in front of us and turn it about in our fingers, what then is the real shape of the quarter?

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Quinn phil
 
Reply Sat 13 Feb, 2010 01:13 am
@Pythagorean,
Pythagorean;127778 wrote:
Correct.



Correct. Just viewing something can't reveal it's true size.

---

I'd like to ask what I think is a related question: If we hold the quarter up in front of us and turn it about in our fingers, what then is the real shape of the quarter?

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Perspective cannot change matter directly, only perceive it in different ways. Everything is subjective, I believe, but the shape of a quarter is agreed upon a certain shape.

Maybe we shouldn't determine something's shape by only looking at it once, from one angle.

Maybe before determining, we should analyze all parts of the object before we pronounce it as the agreed upon term: (Circle, cube, square).
 
Scottydamion
 
Reply Sat 13 Feb, 2010 01:21 am
@Pythagorean,
Pythagorean;127778 wrote:
Correct.



Correct. Just viewing something can't reveal it's true size.

---

I'd like to ask what I think is a related question: If we hold the quarter up in front of us and turn it about in our fingers, what then is the real shape of the quarter?

--


Are you planning on giving some answers of your own anytime soon? Because I don't see the point of this yet... or at least I don't see the point in you using the world "real" in every question.
 
Pythagorean
 
Reply Sat 13 Feb, 2010 02:04 am
@Quinn phil,
Quinn;127780 wrote:
Perspective cannot change matter directly, only perceive it in different ways. Everything is subjective, I believe, but the shape of a quarter is agreed upon a certain shape.

Maybe we shouldn't determine something's shape by only looking at it once, from one angle.

Maybe before determining, we should analyze all parts of the object before we pronounce it as the agreed upon term: (Circle, cube, square).


I agree in spirit of this way of going about the problem: as you say, analyze all parts of the object: Circle, cube, square.


But if we came up with a shape that everyone agreed upon, what would be the status of this standardized agreement? It would remain 'subjective', as you say. The point is, why would such a simple question as 'What is the real or true shape of a coin' be so problematic? What exactly makes it subjective? The very claim that these common things are subjective is rather dramatic and would not be agreed upon by all people.

We need to further develop, and then apply, this theory of perceptual relativity to the very questions we are posing.

---------- Post added 02-13-2010 at 03:10 AM ----------

Scottydamion;127782 wrote:
Are you planning on giving some answers of your own anytime soon? Because I don't see the point of this yet... or at least I don't see the point in you using the world "real" in every question.



Sorry, Scotty. I think we should be using the word 'true' instead of 'real'. The answer is that there is no 'empircal' reality or truth. The standards of men are falsifications.
 
Alan McDougall
 
Reply Sat 13 Feb, 2010 03:24 am
@Pythagorean,
Astronomers use Cepheid variable stars (Standard Candles) to assess size and distance. Using the same idea of a candle light dimming due to distance they can work out both the brightness size and distance of objects near its vicinity

There are whole Cepheid Galaxies like great light houses shining in the cosmos

Standard Candles

The term standard candle applies to celestial objects with well-defined absolute magnitudes which are assumed to not vary with age or distance. Type I and II Cepheids and RR Lyraes are all examples. All Cepheids with a certain period are assumed to have the same absolute magnitude.

Measuring the apparent magnitude of a Cepheid then allows us to determine its distance using the period-luminosity relationship. If two Cepheids have the same period but is fainter than the other it must be further away. RR Lyraes similarly can be used as standard candles although as their intrinsic luminosity is lower than Classical Cepheids they cannot be detected at the great distances of Cepheids.

Type Ia supernovae may be approximated to standard candles as their absolute magnitude reaches about -19 at maximum brightness. Given their extreme luminosity they can be used to probe much further out into the Universe than Cepheids. Two recent projects, the Supernova Cosmology Project and the High-Z SN Search have both observed dozens of supernovae in distant galaxies to try and determine H and the geometry of the Universe.

Both teams independently arrived at the the conclusion that not only is our Universe expanding but it is actually accelerating, a result that the prestigious American magazine Science announced was the research advance of 1998.
 
Krumple
 
Reply Sat 13 Feb, 2010 08:11 am
@Pythagorean,
Pythagorean;127695 wrote:
At what distance must an object be from a perceiver in order for its appearance to equal its real size?


Well what you are referring to is perspective. It's relative even though the object never actually changes size. The object is always equal to it's real size no matter how far away you are from it. So what you are asking is if there is a distance that equals the size of an object. The answer is no because you can't use perspective to measure, you can only use a tool to measure at a perspective.
 
Pythagorean
 
Reply Sat 13 Feb, 2010 10:50 pm
@Krumple,
Krumple;127842 wrote:
Well what you are referring to is perspective. It's relative even though the object never actually changes size. The object is always equal to it's real size no matter how far away you are from it. So what you are asking is if there is a distance that equals the size of an object. The answer is no because you can't use perspective to measure, you can only use a tool to measure at a perspective.



That is incorrect. What possible "tool" would you say we use to obtain the true size or true shape of the coin????

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Krumple
 
Reply Sat 13 Feb, 2010 10:59 pm
@Pythagorean,
Pythagorean;128058 wrote:
That is incorrect. What possible "tool" would you say we use to obtain the true size or true shape of the coin???


The tool I am referring to is anything that use to compare a length or distance with.

For example, lets use an apple. If we measure that apple using a measuring tool, Oh I don't know, a ruler? Let's say the apple is four inches tall. No matter how far away the apple is it will ALWAYS be four inches tall. Even if you put your eye right up against the apple so it is just a fraction of an inch away from the apple, how tall is the apple? It is four inches tall. No matter what distance you stand away from the apple it will always be four inches, but what you are suggesting is that there is a distance when four inches of an object would match it's four inches in height. The answer is never. Because perspective can not be measured by itself, you MUST use a tool. That tool dictates a length and that length will always be determined by the tool, and not perspective. Therefore you can not have an equal distance to perspective ratio of 1:1.

Even if you try this, it will only prove I'm right.

Hold up a ruler near one eye and close the other eye so you can only see the face of the ruler with the open eye and make out atleast four inches in your view perspective. Now place an apple at the distance where the apple stretches across the ruler the whole four inches. I bet you'll have to get pretty close to the apple before it stretches the whole four inches. However; if you move the ruler farther away, the apple can be farther away before it fills the distance between the four inches of the ruler. This proves that perspective is not based on any unit of measure and because of this we can use any arbitrary tool to measure distances. It is also why there is special training involved in teaching people how to judge distances professionally.
 
Scottydamion
 
Reply Sat 13 Feb, 2010 11:36 pm
@Krumple,
Krumple;128060 wrote:
The tool I am referring to is anything that use to compare a length or distance with.

For example, lets use an apple. If we measure that apple using a measuring tool, Oh I don't know, a ruler? Let's say the apple is four inches tall. No matter how far away the apple is it will ALWAYS be four inches tall. Even if you put your eye right up against the apple so it is just a fraction of an inch away from the apple, how tall is the apple? It is four inches tall. No matter what distance you stand away from the apple it will always be four inches, but what you are suggesting is that there is a distance when four inches of an object would match it's four inches in height. The answer is never. Because perspective can not be measured by itself, you MUST use a tool. That tool dictates a length and that length will always be determined by the tool, and not perspective. Therefore you can not have an equal distance to perspective ratio of 1:1.

Even if you try this, it will only prove I'm right.

Hold up a ruler near one eye and close the other eye so you can only see the face of the ruler with the open eye and make out atleast four inches in your view perspective. Now place an apple at the distance where the apple stretches across the ruler the whole four inches. I bet you'll have to get pretty close to the apple before it stretches the whole four inches. However; if you move the ruler farther away, the apple can be farther away before it fills the distance between the four inches of the ruler. This proves that perspective is not based on any unit of measure and because of this we can use any arbitrary tool to measure distances. It is also why there is special training involved in teaching people how to judge distances professionally.


Agreed, except that he is talking about true size and true shape... to me it's as if he is trolling without knowing it yet.
 
 

 
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