Frame of Reference as Subject in Subjective Idealism

[md65536]

I will let my case against length contraction rest with this post.

Excellent. I think we can all leave it at that. There are plenty enough arguments for your version of realism and plenty enough challenges to it throughout this thread.

 

Ps: I said:

 

I will let my case against length contraction rest with this post.

Sorry but we are clearly not done yet until you cite evidence for length contraction. And 'it looks good on paper' (the "model") is not experimental evidence.

Oh my. I dare say you may have gone and trolled yourself there!

 

 

[tar]

OK,

 

To sum up. Objective reality exists. We experience it all from here and now. Even a test instrument will do the same.

We experience it, and measure it from our frame of reference. In this, a FOR is a subjective interpretation of objective reality.

With our abilities to remember, and model, and make analogies, and our ability to put ourselves in someone else's shoes, we can project and understand the nature of objective reality, even beyond the limits of our senses, and that of our equipment. With this "subjective" model we can understand not only what is here and now, but what most likely was before, and what kinds of things are likely to come next. In this, our subjective model, is of an objective reality, that actually is the case.

 

The cap'n and md win. Owl loses.

 

Length contraction and time dilation, due to a FOR moving at relativistic speeds to ours is actually the case.

As surely as you can hold your thumb up at arms length and block out an entire 16 wheeler 1/2mile ahead on the highway, and still know that the truck is "objectively" real (and much bigger than a thumb,) SR describes reality as it actually is.

 

Case closed.

[md65536]

Case closed.

Thanks for the support but unfortunately I have to disagree.

 

 

The case is never really closed. We can often "rest our case" based on existing evidence and have a generally accepted theory, but it will always be open to considering new evidence. owl is not by the way providing any evidence, because the reality he describes ("the Earth is round according to all observations humans have ever made of it") is consistent with relativity. Relativity predicts that all our past observations would have been the way they were (it wouldn't be accepted if it didn't actually correspond with reality, as owl seems to believe).

 

Not all of the claims you made are certain by any stretch.

 

If I've made or tried to make anyone believe that "things are a certain way and that's the exclusive truth" then I haven't won; I've lost, and I'm a loser.

 

The scientist has a lot of experience with ignorance and doubt and uncertainty, and this experience is of very great importance, I think. When a scientist doesn't know the answer to a problem, he is ignorant. When he has a hunch as to what the result is, he is uncertain. And when he is pretty damn sure of what the result is going to be, he is still in some doubt. We have found it of paramount importance that in order to progress, we must recognize our ignorance and leave room for doubt. Scientific knowledge is a body of statements of varying degrees of certainty — some most unsure, some nearly sure, but none absolutely certain. Now, we scientists are used to this, and we take it for granted that it is perfectly consistent to be unsure, that it is possible to live and not know. But I don't know whether everyone realizes this is true. Our freedom to doubt was born out of a struggle against authority in the early days of science. It was a very deep and strong struggle: permit us to question — to doubt — to not be sure. I think that it is important that we do not forget this struggle and thus perhaps lose what we have gained.

-- Richard Feynman

 

Edited October 13, 2011 by md65536

[tar]

MD,

 

I obviously have some doubts. It is well known that science progresses and new discoveries often automatically rearrange our models of the world.

 

Owl was resting his case. I was not convinced.

 

To move forward on this discussion, in my estimation is to exactly not consider one's own model "certain".

To do so is the mistake any "dogma" makes.

 

I have, and do, consider that there is "truth" in the model that every single person on this planet holds. The models are not the same and the "best" model possible is one that "includes" everybody's personal model.

 

I have been on a train of thought, or an investigation into the "nature" of this basic dilema we face. Our own model is the "only" one we are capable of holding. Yet we know there are others. In this, SR is an "improvement" over a model that considers this FOR "preferred". It establishes a framework in which "true" things exist that can not be seen except by stepping into someone else's shoes. There are some places, where this concept can be used in arguments both for and against science or religion. From either perpective, the other makes unreal claims, that don't fit the "model" held by the model holder. What often or always follows is a "strawman" argument where one finds the "inconsistencies" of the other's model, based on where they are inconsistent with their own.

 

In the history of Western civilization, it is interesting to note that Moses addressed this question and realized that there is in actually only one God, only one nature, only one reality that we are all subject to. Mohammed made the same realization and urged all the idol worshippers in his region to recognize their "error" and submit to the one reality.

 

Science is an attempt to reach the truth through discovering things about reality that are evident to anybody and everybody, anytime, anywhere, following any possible trajectory. Same basic parameters are engaged in any human endevor to understand our existence. We exist, the world exists. We each hold a model of it, that includes all of it. It is my body, my family, my town, my state, my country, my Earth, my Solar System, my Galaxy, my Universe, yet other's models are of many of the same things. It is their universe too.

 

Regards, TAR2

[owl]

Here is a review of the first five pages of this thread showing the run-around I've been getting on this topic, particularly on how reality depends, in relativity, on frames of reference, i.e., that there IS no objective shape of earth, as the 'key note' example.

Somewhere in the thread, also, is DrRocket's statement that there is no experimental validation of (large scale)* length contraction... a point continually avoided by its advocates.

My challenge of the supposed particle accelerator validation was met with an offer to ask questions of an expert, Cap 'n R's boss, which I did, but they went unanswered.

 

From post 16:

me:

For instance, don't we we all know that earth does not actually flatten out (in the direction of motion) as seen/measured from a near 'C' fly-by frame of reference?

 

Cap 'n R:

No, we don't. How could we?

 

From post 37:

me:

Likewise we know from the whole field of earth science that it is a relatively rigid and nearly spherical body.

Cap n R;

I dunno; the Earth scientists I asked as they shot past on their rocket were very definite about the Earth being a remarkably oblate spheroid. Apparently it looks like it's been squished in one direction. I can't imagine how you could think the Earth is nearly spherical; it's a tough, rigid body, so stretching it out to a sphere would be impossible. You just can't do that with solid rock.

 

(A little humor there... but the point is clear.)

 

From post 42: Cap ‘n R:

If we consider the space of velocities and directions I may travel in, very few possibilities have a spherical Earth. The majority of situations, if you chose randomly, would have an observer traveling at a significant fraction of light speed compared to Earth. Face it: you're outnumbered by hypothetical observers.

 

Different FORs yield different realities.

 

DrRocket from post 43:

Actually a sphere passing by at relativistic speeds LOOKS LIKE a sphere. The flattening is not observed, due to the finite speed of light. There is a big difference between the actual dimensions and what would be seen by an eye or a camera. ...

On the other hand, an actual measurement, could it be performed, would show the sphere to be highly oblate. Appearances can be deceiving.

 

From swansont’s post 45:

me:

What objective tests? The orbit of satellites would be radically different if earth were an oblate spheroid. The view of earth from the space station would not see a round (spherical) earth if the extreme frame were an accurate description. Mechanically, we know that earth does not actually flatten out, because we know it is a semi-rigid body. The surface survey which yielded the standardized, earth commensurate meter would have found a different length if earth had a way longer axis length than girth through the equator, or vice-versa. How many more objective tests would it take to establish the “true shape and size” of our planet?

S:

In the frame of the fast rocket, yes they would be radically different, just as the shape of the earth is radically different. But you you can't hop between frames and mix up measurements and quantities (unless they are invariant)

 

(My bold edit.) That's "is radically different", not "appears different."

 

Cap n R, post 47 (my ** emphasis):

**

The key point against relativity being a form of subjective idealism is that observations in any reference frame can be transformed into observations from another frame using a predictable and consistent mathematical formula. I can determine exactly what should be observed in any reference frame if I know what I observe in mine. That's hardly subjective. **

 

This leaves the philosophical challenge of realism and objectivity unanswered.

 

Wikipedia on Philosophical Realism:

Contemporary philosophical realism is the belief that our reality is completely ontologically independent of our conceptual schemes, linguistic practices, beliefs, etc.

In epistemology realism is accounted a subcategory of objectivism.

 

 

Wikipedia on Objectivity as a philosophy:

 

Objectivism, in this context, is an alternative name for philosophical realism, the view that there is a reality, or ontological realm of objects and facts, that exists independent of the mind.

 

I replied to post 47 in part as follows:

Now we are making progress in communication*. I have often/repeatedly credited relativity with the above, which is why I am not about debunking relativity in general. Yes, its formulae keep us all on the same page for accurate GPS positioning too, even while relativity effects make clocks go bonkers.

 

Likewise we can take the squished earth as seen from high velocity, apply the Lorenz transformation formula and transform the squished earth back to its "actual" shape in the real/objective world... Right?

*So I thought.

Post 49:

me:

I'm betting you say "wrong," and continue to insist that the squished earth is just as accurate a description as the spherical one we all know and love!

Cap ‘n R:

Well, it is.

 

But I can take the squished Earth and use the relative velocity between Earth and observer to calculate what an observer sitting on Earth would see, and I would calculate that he'd see something very nearly spherical.

(my bold.)

Note: “squished earth” is just as accurate as “nearly spherical earth.” Realism? Objective, intrinsic earth. Not.

 

Post 50:

(DrRocket quoting Cap 'n R):

“But I can ...calculate ...."

DrRocket:

And therein lies the difference between you and owl.

 

But is there an objective shape of Earth or not? And if so, what is that shape? The answers do not require calculation. They are, "yes," and "very nearly spherical."

 

Cap ‘n R:

Earth science has thoroughly established Earth as nearly spherical in our reference frame. A physicist can tell you exactly what it will look like in any other reference frame.

 

See thread title yet again.

What it looks like from different frames is not disputed (much) here. (See DrRocket’s comments in post 43 above.) The question here is... Does Earth have an objective, intrinsic shape independent how it might be seen from different FORs? (Ans: Yes.)

 

From post 57:

me:

But they don’t co-relate deeply enough to recognize that earth has* a given shape (nearly spherical) all by itself ("an objective earth"), independent of frames of reference from which it is seen (*and has had long before relativistic frames of reference were even thought of.)

Cap ‘n R:

That's because it doesn't.

(my bold)... It doesn't have a shape "all by itself" independent of FORs.

 

From post 62 on length contraction as seen from a muon’s FOR :

Cap ‘n R:

The atmosphere doesn't "get" thinner; it is thinner in their reference frame.

(my bold)

So FOR determines how thick the atmosphere IS.

 

From my post 65, quoting Cap ‘n R:

The Earth does not deform.

When viewed from another reference frame,** it IS a different shape**. It has always been that shape and it always will be, in that reference frame. That is why Earth's rigidity does not enter into it.

 

(My** emphasis.)

Definition of philosophical realism from Wikipedia:

Realism, Realist or Realistic are terms that describe any manifestation of philosophical realism, the belief that reality exists independently of observers, whether in philosophy itself or in the applied arts and sciences. In this broad sense it is frequently contrasted with Idealism.

 

From my post 78:

It can not be both ways: "Earth does not change shape...", and "Earth is flattened between the poles..." (for one FOR), *and* "Earth is flattened through its equatorial diameter" (for another FOR.)

Deal with it. (Please.)

 

... to which Cap ‘n R replied:

Why not? When I sit in one reference frame, I will never see Earth change shape. The shape is only different between reference frames.

 

...”the shape IS (only) different between reference frames.”

 

Not “appears different” but “is different.” FOR determines what shape earth IS.

 

From my 82:

To include the spherical option,

all four of the following statements can not be true.

#1: Earth is nearly spherical.

#2: Earth does not change shape.

#3: Earth is flattened between the poles.

#4: Earth is flattened through the equator.

 

The 'all frames give equally valid descriptions' dictum clearly runs into a brick wall here. You really can't have all of the above be true.

 

The Cap ‘n replied that all of the above can be true if amended to “in (this or that) reference frame," in all cases. Reality depends on FOR... no intrinsic, objective real world. Earth's true shape can not be known.

 

From my 86:

Do you agree that the above means that there is no objective, as-it-is shape of earth?

Cap ‘n R:

Not across all reference frames, no.

 

Repeat: There is no objective, as-is shape of earth. FORs determine reality.

[tar]

The truck is smaller than my thumb.

The truck is bigger than the car I am in.

The truck remains 1/2mile away from me.

The truck is traveling 64 miles per hour.

I am sitting still in my car.

All these dictums cannot be true. They are contratictory.

 

Owl,

 

Taking more than one frame of reference into account, one can sort out the inconsistencies and know how to translate from one frame to the other. Yes the truck is real, and is measured small and stationary if you are far away and moving at the same speed. And if you are close and moving at the same speed relative to the road it measures rather large.

 

What size IS the truck?

 

(it is the size that is consistent with ALL FORs)

 

Regards, TAR

Edited October 14, 2011 by tar

[owl]

So, it's settled then, as my last statement (and my last posting showing the run-around I got on this topic) remains unchallenged.

[questionposter]

Idealism is relative of course, this has been discovered already. I'll even give you a situation where it comes in handy.

 

A wolf is chasing a rabbit to eat it. Is the wolf evil for chasing the rabbit? Is the rabbit evil for not feeding the wolf? It depends on the perspective. To the rabbit, the wolf eating it is evil. To the wolf, eating a rabbit is good.

 

 

Look at how a frame of reference plays in that.

Edited October 19, 2011 by questionposter

[Schrödinger's hat]

So, it's settled then, as my last statement (and my last posting showing the run-around I got on this topic) remains unchallenged.

 

Possibly because everyone got tired of the constant bickering over minutae and reiteration of the same points.

 

I'm not even sure what you were trying to say with that last post.

If you were trying to say that we are saying, "The (3d) shape of an object depends on the reference frame you choose." Then yes, this is what we were saying all along. (3d) Shape is not frame invariant. This in no way implies that reality is frame dependant or subjective. Given the measurements of a system in any frame, the measurements in any other system can be calculated.

There are certain quantities (interval, magnitude of any four-vectors such as energy-momentum, order of causally connected events) that do not change between frames.

There are other quantities (distances, times, order of non-causally connected events) that do change.

 

You can pick a certain set of events which are simultaneous in one frame and call it 'now' if you really want thus declaring any measurements taken outside of this frame as incorrect. It's just that there's never been any evidence that the 'now' you pick is the correct one (or any more likely to be correct than any other set of events that someone measures to be simultaneous).

 

If you're trying to say that the rest shape (shape of an object in a frame where that object is at rest) is objective then that is also true. So is the shape in any other reference frame, you just have to supply the velocity of the frame you're in before shape can be defined.

[owl]

name='Schrödinger's hat' timestamp='1319203521' post='633064'

 

I'm not even sure what you were trying to say with that last post.

(quote tags not matching.??)

So in spite of your criticism of my repetition, you need me to repeat my point. OK, here it is again:

My question to Cap 'n R:

Do you agree that the above means that there is no objective, as-it-is shape of earth?

Cap ‘n R:

Not across all reference frames, no.

 

Repeat: There is no objective, as-is shape of earth. FORs determine reality.

"Shape of Earth" was my "keynote example" for criticizing length contraction. Earth does not change shape (much.) It is in fact nearly spherical. If its shape depended on observational frames of reference, as Cap' n insists, as above, then "a severely oblate spheroid" might be an equally valid description. The point of the thread is made clear.

You:

If you were trying to say that we are saying, "The (3d) shape of an object depends on the reference frame you choose." Then yes, this is what we were saying all along. (3d) Shape is not frame invariant.

No. Multiple repetitons didn't help you understand what I have been saying all along. And you clearly didn't bother to study the Kelley Ross paper on how the notion of 4-D spacetime (and 4-D objects) developed. Regardless of the theoretical manifolds (including the 4-D concept) developed in non-euclidean geometry, actual objects in the real world, like planet Earth are, intrinsically, objectively three dimensional. (Three axes... count 'em... describe all volume, space and objects with volume.) As an object which exists independent of observational FOR earth stays nearly spherical regardless of the FOR from which it is observed... the point of this thread... and this contradicts relativity's claim about the equal validity of all FORs in describing earth.

This in no way implies that reality is frame dependant or subjective.

Except that the reality of earth's shape depends on the FOR from which it is measured/observed. Yes, quite repetitive!

 

Compared to the above major point, made many times in my "first five pages summary post), most of the rest of your objections are, as you say "minutia," and I will not "quibble"* over them if you still don't get what I said, yet again above.

*(Maybe just a little...)

 

There are other quantities (distances, times, order of non-causally connected events) that do change.

 

You never did understand my "imagine no intelligent life observing..." challenge. Everything, of course is moving. That said, the average distance between earth and sun does not change with observational FOR. Cosmos and all its parts exist and have properties and relationships (like distances between them) intrinsically, objectively, independently of any/all frames of reference from which they are observed. (Oopse, there I said it again!)

 

You can pick a certain set of events which are simultaneous in one frame and call it 'now' if you really want thus declaring any measurements taken outside of this frame as incorrect. It's just that there's never been any evidence that the 'now' you pick is the correct one (or any more likely to be correct than any other set of events that someone measures to be simultaneous).

 

If, for one moment you could set aside the quite ironic absolute belief that "everything is relative," depending on frames of reference, you might see that, as per "presentism" "the present IS now everywhere." I know that relativity denies this ( i.e., the "relativity of simultenaity," introducing distances between and velocities of different FORs, as a different "now" for each, but that does not make presentism wrong. In fact it attempts to re-define "IS," making the present dependent on location/velocity of FORs... "time cones" and all.

If you're trying to say that the rest shape (shape of an object in a frame where that object is at rest) is objective then that is also true.

I am saying (over and over) that the shape of an object, according to realism, does not depend on the frame from which it is observed, whether at rest with it or flying by at very high speed.

So is the shape in any other reference frame, you just have to supply the velocity of the frame you're in before shape can be defined.

Objects don't actually change shape "in other reference frames." (Theme of thread.) I'm glad that the Lorentz transformation formulae are useful in finding the true shape of objects, translated from whatever "distortion" due to extreme relativity effects, but all length contraction advocates in this thread have denied that those effects are "distortions."

See again me 'n the Cap 'n above:

Me:... "that there is no objective, as-it-is shape of earth?"

Cap ‘n:

"Not across all reference frames, no."

Can I rest my case now?

[owl]

One last try, then I'll quit on it. Still trying to reconcile what we know about earth's shape (and the distance between cosmic bodies) with what we know about the constant speed of light as per SR. (I know about the experiments confirming this.)

It really is a philosophical question. *If* earth has a shape all its own, independent of frames of reference and how we look at it, and *if* that shape does not change (drastically morph) then can we know that shape, as given by lots of measurements in the at rest frame with earth, or do other frames of reference actually yield equally valid descriptions, like the very oblate spheroid from a high speed frame?

 

If the latter is true, then earth has no "true shape" and all distances between objects depend on how you look at them.

The latter says that cosmos has no reality of its own, because it all depends on how we look at it. I was calling that philosophy a contemporary form of idealism. I would appreciate replies that are philosophically astute about the issue as stated, not just reiteration of the SR claim that length is not invariant or that there are no preferred frames of reference.

Thanks. This is a sincere (continuing) inquiry and I hope we can keep it civil?

[DrRocket]

One last try, then I'll quit on it.

 

Good to have that in writing.

[owl]

Good to have that in writing.

About my request for civility; is that too much to ask?

How about an equally sincere reply to my post? Or is it not a legitimate question? If not, why not. Does SR make knowing earth's shape impossible?

[DrRocket]

How about an equally sincere reply to my post?

 

 

I could not possibly have been more sincere. I devooutly hope your promise was equally sincere.

Edited February 1, 2012 by DrRocket

[swansont]

!

Moderator Note

One discussion on this has already been closed down. That generally means don't reintroduce the topic; here we have the unusual situation where there were multiple threads because we didn't merge them. But the idea remains — there's nothing new to cover. We're done.

[owl]

 

Good thing I did none of that then. Thanks for showing your utter incompetence again as demonstration, though.[/Quote]

 

The above in reference to my:

It's a very good thing that neither astute philosophy nor valid science depends on personal opinion or "popularity." It's also good that ad hominem personal attacks carry no weight at all as valid argument.

 

I will let others here decide whether or not you did any of that. More personal insults... all you have to show here so far... no serious argument on the points of dispute.

 

Yep, including psychiatry. Remember where I showed again and again that you haven't gotten the faintest clue about human memory and testimony? Yeah, that bit.

 

Was that where you didn't know the difference between psychology and psychiatry, or was that someone else?

 

That was your argument, that memory can be wrong. True, it can. So, your argument goes, therefore my memory of the event might be wrong. True, but it wasn't in this case. The context and private documents verify the accuracy of my account here.. Your disbelief, or more directly, your conviction that I am a liar does not invalidate the truth of the account as I gave it.

 

Actually, contemporary philosophy has already answered those questions. You just don't understand math and refuse to accept it.

 

Please be more specific. How do you think "those questions" have already been answered?

 

The elitism of hiding behind 'You don't know the math' does nothing to address the issues I've raised here.

 

How about those intersecting "parallel lines" for openers? Too much philosophy, or do you have an answer to how parallel lines somehow intersect in the 'new geometry' of math's "infinite?"

[ydoaPs]

I'm still waiting on one discipline of philosophy outside of science/logics that carries any credence at all.

 

Ethics? Heterophenomenology? Epistemology?

 

The above in reference to my:

 

 

I will let others here decide whether or not you did any of that. More personal insults... all you have to show here so far... no serious argument on the points of dispute.

 

 

I suggest you look up what the "Ad Hominem" fallacy actually is lest you make yourself look more of a fool.

 

Was that where you didn't know the difference between psychology and psychiatry, or was that someone else?

 

Not me.

 

That was your argument, that memory can be wrong. True, it can. So, your argument goes, therefore my memory of the event might be wrong. True, but it wasn't in this case. The context and private documents verify the accuracy of my account here.

 

No, my argument was that the example you provided is a prime example of when memory would have been false. You still have yet to give any reason to think the memory hasn't been altered.

 

Please be more specific. How do you think "those questions" have already been answered?

 

See every thread you've ever posted in regarding the topic as well as any modern book written on the subject not written by an idiot that doesn't understand math.

 

How about those intersecting "parallel lines" for openers? Too much philosophy, or do you have an answer to how parallel lines somehow intersect in the 'new geometry' of math's "infinite?"

 

In curved spaces, parallel lines can indeed intersect. See, lines are parallel if they have equal constant first derivatives. In curved spaces such lines can, and often do, intersect.

Edited March 29, 2012 by ydoaPs

[owl]

I suggest you look up what the "Ad Hominem" fallacy actually is lest you make yourself look more of a fool.[/Quote]

 

Without the need to look it up, I'm sure it means literally "to the person," usually in a way to make the other person the object of criticism rather than addressing the points of substance in the argument.

 

In curved spaces, parallel lines can indeed intersect. See, lines are parallel if they have equal constant first derivatives. In curved spaces such lines can, and often do, intersect.

 

How does that work? How do they remain parallel if they intersect, if you accept the challenge to make sense here.

 

First, "curved spaces" are theoretically assumed after Euclidean space is discarded, without addressing the transition or its validity.

 

"Equal constant first derivatives" is evasive lingo avoiding any explanation of non-Euclidean "intersecting of parallel lines."

 

From Wikipedia on parallel geometry:

Parallelism is a term in geometry and in everyday life that refers to a property in Euclidean space of two or more lines or planes, or a combination of these. The assumed existence and properties of parallel lines are the basis of Euclid's parallel postulate. Two lines in a plane that do not intersect or touch at a point are called parallel lines. Likewise, a line and a plane, or two planes, in three-dimensional Euclidean space that do not share a point are said to be parallel.

 

In a non-Euclidean space, parallel lines are those that intersect only in the limit at infinity.

 

The last quoted sentence above is non-Euclidean b.s. asserting a lame metaphysical/mathematical conjecture, "in the limit of infinity" depending on assuming theoretical "curved space" and the mystical math of infinity, all of which is derived from rejecting the 5th postulate in the first place and 'making the lines intersect', i.e., no longer "parallel."

 

No, my argument was that the example you provided is a prime example of when memory would have been false. You still have yet to give any reason to think the memory hasn't been altered.

 

"Would have been false?"

I granted "could have been." I also gave good reasons why that was unlikely, given immediate documentation in one case, agreeing with my memory as shared here, and corrected memory in the last case, already detailed in depth.

 

In your own terms, reversed, 'you still have yet to give any reason to think the memory has been altered.'

You claim to falsify my testimony. The burden is on you to give reason that it is false... and calling me a liar (perhaps just implied) or demented, without reasonable memory capacity would not be a good "reason."

 

To my:

"Please be more specific. How do you think "those questions" have already been answered?"...

You broad-brush-stroke it away with a gross generalization:

 

See every thread you've ever posted in regarding the topic as well as any modern book written on the subject not written by an idiot that doesn't understand math.

...

 

You call my well credentialed sources "idiots" in general. You take science very personally, attacking whomever disagrees with you, and all answers must agree with your own biases.

 

I was a psychologist, not a psychiatrist, which most everyone knows, requires a medical degree. You were confused (or didn't know the difference) in your eagerness to discredit me.

[tar]

Owl,

 

You never answered my challenge.

 

What is the shape of the edge of the shadow(penumbra) cast by the Earth? Straight or curved?

 

Regards, TAR2

Edited March 29, 2012 by tar

[hypervalent_iodine]

!

Moderator Note

Posts 517 onwards have been split from this thread. Owl, do not bring up this topic again or you're looking at suspension.