How important is a viewpoint?

[abskebabs]

Hey everybody, I was wondering the other day how important is the abillity to have a viewpoint of the underlying processes involved for a physical theory? How important is this to allow theory to be considered theoretically plausible by the scientific community. I am concentrating on theories in the field of Physics, which was I posted in this part of the forum.

 

I shall help to illustrate, using 2 examples.

 

You may or may not know, in ancient times, the egyptians and babylonians had already developed accurate mathematical models that were able to predict the movement of the stars and constellations. However, the Ptolemaic model, whose predictions were not as accurate, still became generally preferred over these older, more accurate models. This seems to me because it provided a viewpoint and a basis for what was happenning that at the time seemed plausible.

 

My 2nd example is at time much further along the road of history. During the 1920s, when Heisenberg came up with matrix mechanics in the field of Quantum theory, Schrodinger among others, very much disliked for its lack of a viewpoint, or illustration of the processes involved. He developed his own version of Quantum mechanics based on wavefunctions and the now famous Schrodinger equation. I think it is generally thought to be easier to use. It was later shown however, that both theorie were mathematically equivalent.

 

In light of this, I would like to summarise by reiterating my original question, how important do you think it is, that when we develop physical theories we maintain a viewpoint?

[swansont]

Ad-hoc is generally insufficient; you do need a mechanism. Lorentz, for example, came up with an equation that explained the Michelson-Morley experiment. It's the same as the length contraction equation from relativity, but Lorentz didn't have a mechanism, so it wasn't sufficient. Einstein gets the credit, because you can arrive at the Lorentz transform from the postulates of relativity.

[Locrian]

I generally agree with swansont, but with a gigantic disclaimer: while an understanding of the underlying processes is important, the degree to which it is necessary depends wildly on your system, your field and your application.

 

When talking about elementary physical systems it is easy to think in binary when discussing whether you have some more fundamental understanding you say "we do" or "we don't." It is not so easy in other areas. I will use the area I've worked in for a while now as an example: in CVD diamond growth, the actual process of diamond growth is very poorly understood in a general sense. In some simplistic cases a reasonable model is available, but it cannot be said we have anywhere near a thorough understanding of what occurs in the growth process under the variety of conditions it is done.

 

And what's important here, is that this hasn't prevented the field from making great progress. I believe you can argue that it might have hindered it, but research goes on. There is a vast landscape of possible experiments one can do in this area that will change the outcome of your experiment in ways that are difficult to predict. This gets no one's approval, but it is certainly not the end of the story.

 

You will hear many, many examples such as that as you study matter in more and more complex systems.

[ajb]

By viewpoint do you really mean a physical interpretation of a theory?

 

If this is so, I am unsure if it is important. Clearly, having some kind of interpretation if useful for explaining results and calculations to a wider audience or to present hand-waving arguments. However, it could never be a substitue for hard calculations.

 

That said some physical insight can be very useful when doing mathematics.

[abskebabs]

By viewpoint do you really mean a physical interpretation of a theory?

 

If this is so' date=' I am unsure if it is important. Clearly, having some kind of interpretation if useful for explaining results and calculations to a wider audience or to present hand-waving arguments. However, it could never be a substitue for hard calculations.

 

That said some physical insight can be very useful when doing mathematics.[/quote']

 

Yes, essentially, this is what I am getting at. It seems to me that it is important to have both the hard math as well as providing as best a picture as possible of the underlying processes in any theory. The impression I get though, and I may be wrong with this, is that more recently the importance of producing a picture has dropped.

 

One example of where a picture is not so important, or is not thought to be needed is what happens when quanta are diffracted through a double slit to a screen. According to the Copenhagen(regular) interpretation of quantum mechanics, what happens in between is not considered to be of importance and we can only say anything about the maxima and minima we observe on the screen adn their location. Am I wrong here?

[Bignose]

The application disclaimer is very apt. On many engineering scales, that is, plant level, ad hoc or rules of thumb can be more than sufficeint. Many, many plants have been designed on this without the desingers knowning the basics underlying everything. Real good case in point: turbulence. Many of the broader implications of turbulence are known, and almost every flow on a plant scale is turbulent, but no model can capture every detail of the turbuelnce at all speeds to date. Just because the basic details are not known, and many desingers use simplified models of the turbulence, does not mean those designers are any less successful at their jobs. That said, better understand of the physcial insights have led to better and better turblence models over the years.

[ajb]

I have spoken to several scientists about this in the past. Some think it is very important to have an interpretation and other not so important.

 

One problem with interpretations is that they can be misleaing. This is often the case in popular science.

 

Personally, I think that an interpretation is important and useful, but no substitute for mathematics.

[h4tt3n]

Beeing a scool physics teacher, I think the importance of using images or points of view cannot be underestimated. Just because you are able to describe a physical phenomenon mathematically, it doesn't mean that you understand what is going on. On the contrary...

In my life time I've seen several examples of really smart people who, despite the fact that they were able to do complicated math on a subject, didn't really understand it:

 

Once I had to explain how objects fall at the same speed regardless of mass to an older student who at the time had already done a really excellent paper on gravity and orbits.

Allthough he was able to describe these phenomenons mathematically, he was unable to "translate" the mathematics into a common sense understanding of how it works in everyday life. The discussion led to a really silly experiment including a crude home-made tower and several bottles with different contents, which didn't really prove anything...

 

At least I think this point of view applies to classical mechanics and perhaps GR - I'm aware that something similar is much harder to do with QM

 

Best regards,

Michael

[ajb]

To understand something I think you should have both a "mental picture" and be able to understand the mathematics and compute things.

 

Without the mathematical framework, you cannot say that you understand something. Most crackpots and people with "new theories" simply do not understand the mathematics of current thinking and hence dispute them.

 

But at the end of the day, physics (to me at least) is an attempt to describe the natural world using mathematical models. Some of these models are hard to describe, such as quantum mechanics.

[Locrian]

Once I had to explain how objects fall at the same speed regardless of mass to an older student who at the time had already done a really excellent paper on gravity and orbits.

Allthough he was able to describe these phenomenons mathematically' date=' he was unable to "translate" the mathematics into a common sense understanding of how it works in everyday life. [/quote']

 

Well, in everyday life things with different masses don't fall at the same speeds, even if they have the same geometry. Maybe it's not so common sense after all?

[h4tt3n]

The difference would be indetectible to the human eye and to quite a lot of measuring instruments. If you insist on applying GR to everyday events like falling jelly sandwiches and the sort, then of course no laws within the area of classical mechanics are 100% accurate. But honestly, what's the point? Common sense prevails!

[Locrian]

Well I'm not talking about GR. Acceleration due to gravity isn't mass dependant; acceleration due to friction is, inversley. That heavier objects fall faster than lighter ones that are the same shape and volume is a fact well known to every skydiver.

 

Can't get more classical or common sense than that.