the model versus the "reality".

[geordief]

I agree with disarray's last points. Can we start a campaign for the proscription of the use of the term "reality" for the under 18's?

 

If "reality" could be shown to actually exist it might be like a mini black hole and swallow us up.. Incompleteness is far more satisfying (or was that dissatisfying? ..whatever)

 

I also liked his analogy in post#20 of the deity sitting at the pixelated TV screen. Did he then ,mythologically disperse the pixels with a sneeze ,blow away the cobwebs and proclaim ,"hey presto welcome Creation!" ,knocking over the pile of turtles as he did so ?

Edited June 26, 2016 by geordief

[Markus Hanke]

We are far away now from anything that can even remotely be considered physics.

The role of physics is really quite simple - it makes models of the universe around us, not more and not less. Given any particular model, there are really only two valid questions we can ask :

 

1. Is the model a good model ?

2. Is the model a complete model ?

 

The first question is ( given access to the right technology ) easy to answer, by comparing the predictions of the model to empirical data ( i.e. measurement results ). The second question is somewhat more involved, but can also be answered by examining the constraints a model places on the space of all possible preparations and measurement outcomes; this is what happened ( e.g. ) with the controversy about hidden variables, and Alain Aspect's experiments. That's all physics. What is not physics is any number of other questions, such as

 

1. Is the model the truth ?

2. How does the model relate to reality behind the measurements ?

3. Was what the model describes somehow designed ?

4. Why is the model the way it is, and not somehow different ?

 

And so on. Don't get me wrong - these are valid questions in their own right, but they are not question that physics is designed ( or claims ) to be able to answer. They belong to different domains of enquiry. I think it is very important to keep a proper perspective on this, and not confuse physics with something else, such as metaphysics and philosophy. Yes, there are parallels, overlaps, and cross-references between these disciplines, but confusing them and muddling them together leads to nothing good.

 

Just my two cents' worth.

[disarray]

Markus, I take your point. I just mention this because I often read that the question of some ultimate reality is discussed even amongst physicists, and my pont is exactly the same as yours. (I have read, for example, that Einstein and Bohr argued as to whether the moon existed when no one was looking at it. I have read popular articles about quantum theory claiming that scientists ponder how anything could exist before humans were alive to experience it. I have also read that the 'shut up and measure' school of quantum theory supposedly dismisses the question as to what some ultimate reality is really like. )

 

I guess I bring it up in order to show why the questions you mentioned keep popping up, and, like you, to say that they are relevant:

And yes, Plato's Cave syndrome is a philosophical question about reality that affected philosophy for centuries: The idea that what we see is but a paltry, shadowy reflection of some absolute reality which one can experience outside the cave in the sunlight.

I guess the average person gets in the habit of thinking that there is always some reality (the modeled) beyond our models of it because our everyday life is filled with such models, not only because we are surrounded with visual images in the media (instagram, television, facebook, movies, posters, billboards, magazines, etc.) but because we learn before we can even walk that the words in our languages stand for "real" things in the world around us that we can point to ("car" represents the thing we drive around), and also we have an image-ination in which we think about how a person that has been described to us will "real-ly" be like when we meet them later in the day.

 

So no, I don't think that there are limits in the amount of knowledge that we can have about the world. However, speaking to public assumptions about some ultimate reality, I just wanted to point out that we cannot assume that we can always directly experience with our senses what models of reality suggest are there. Perhaps one might call this assumption the 'objective correlative fallacy'.

Edited June 26, 2016 by disarray

[geordief]

 

 

And so on. Don't get me wrong - these are valid questions in their own right, but they are not question that physics is designed ( or claims ) to be able to answer. They belong to different domains of enquiry. I think it is very important to keep a proper perspective on this, and not confuse physics with something else, such as metaphysics and philosophy. Yes, there are parallels, overlaps, and cross-references between these disciplines, but confusing them and muddling them together leads to nothing good.

 

Just my two cents' worth.

I have given you my first and only "like" in over 20 years on the internet. A cumulative "like" like the way a ref hands out red cards after a long series of fouls.

 

I did ask (and Swansont answered) whether these kinds of questions could serve a purpose.

 

I think they can as they provide a framework for the more bread and butter (or croissants and cream) questions but you are right in that any confusion is as bad as sand in the you know where .

 

I know I said wouldn't contribute ,but it was my OP after all and I am accepting the ticking off

[disarray]

I reread the opening post. Perhaps what laypersons want to ask with respect to this thread is not so much a question as to what elusive things such as the curvature of spacetime really, really looks like (as if there were some ultimate reality), but rather how best to visualize it, such as the following passage attempts to help us do:

 

"In curved space-time, there are no straight lines - just as there are no straight lines on the surface of a sphere. The closest we can get to the notion of a straight line is a geodesic, a spacetime curve that is as straight as possible. Test particles in the vicinity of the massive sphere follow these geodesics. Gravity does not reflect them from their straight lines - it re-defines what it means to move on a straightest possible line." http://www.einstein-online.info/spotlights/geometry_force

I think most teachers would agree with the 'multiple intelligences' concept that students learn in various ways. Not everyone is mathematically minded, and, in any case, most all can benefit from visual approximations. (Perhaps a quick comment or footnote might be given that such models, be they visual or whatever, are just practical tools meant to help us understand what we can never really experience, much like we might tell a student that the Bohr atom is just a useful model, and is not meant to show what atoms actually look like if could see them 'in person' so to speak).

 

 

[studiot]

 

Given any particular model, there are really only two valid questions we can ask :

 

 

I see no one was interested in my Oxford model of a model, but don't you think this is a bit limiting?

 

Another valid question might be paraphrased as

 

If the model appears thus today was it the same yesterday and will it be the same tomorrow?

 

Astrophysics is currently wrestling with this exact question.

[Markus Hanke]

If the model appears thus today was it the same yesterday and will it be the same tomorrow?

 

 

Well, I think this is already encapsulated within the question as to validity - a model may be perfectly valid today, based on empirical data available today, but cease to be valid tomorrow based on new data that has become available, and which we didn't have before. That is why no model or theory is ever "proven", it is just continuously tested with increasing levels of accuracy and sophistication. Physics is an ongoing process based on repeated application of the scientific method, not a rigid belief system.

[studiot]

I'm sure you know that I was not referring to improving changing or replacing a model in the light of new and better data.

 

That is 'encapsulated' in the example I gave.

[Mordred]

The flowchart you posted is excellent Studiot

[studiot]

Thanks, Mordred.

 

The point is also that the book was in pure maths but contains some excellent wisdom and is a very good read, not just the extract I posted.

 

It could be called the study of group theory via Scottish Dancing.