Can " Analogies " , serve in our understanding nature ?

[ajb]

It would show that analogies only occur after and "never" before the formulation of models or theories

Usually analogies are, as you say, 'after the fact', in the sense that you use them to present some features of a given model.

 

I would suppose that quite often analogies are used in the 'development' stage, but we are not usually privy to this.

 

Also, we should define what we mean by an analogy. In developing physical theories the analogy may itself be very mathematical; for example using what you know in classical mechanics as an analogy for some features of classical/quantum field theory.

 

Mike I think has more 'mechanical' analogies in mind, something he can see and touch. Like Einstein's trampoline. But don't let me put words in your mouth Mike.

[Strange]

Kekulé said that he dreamed of a snake swallowing its own tail (ourobouros) and that this "analogy" allowed him to solve the problem of the structure of the benzene molecule.

 

There may be a few other examples where an idea ("analogy") has stimulated the development of an idea or solved a problem. But they seem to be very much in the minority.

[Mike Smith Cosmos]

You can use graphical analogies to help explain some feature of a model. You maybe able to use graphical notation an so on...But still by a model we mean a mathematical model. In no way do they replace the hard work.

That last sentence , That's the sort of comment my mother would make !

 

Your comment about some examples . ( remembering , I am not just referring to High School ) but using an example from that time.

I remember being taught about refraction of light through a Glass Block. Young or some one spoke of light having a ' wave Front' bit like the front row of a marching battalion of Scottish highland soldiers . The front row marched toward a swamp , under orders , but at an angle to the edge of the swamp , so the soldiers on the end of the row would enter the swamp first. We were told , imagine the whole column of soldiers , representing a light beam entering a glass block at an angle . As the soldiers entered the swamp , the end ones would be slowed , by dint of it being sludgy and difficult to march in. You can then imagine that as the first row followed by the next rows , row by row , would slew ( by being slower ) , such that the rows ( many now in the swamp) , were again marching in a straight line , but at an angle moved toward the 'normal ' ( a line at right angles to the edge of the swamp or glass block ) ...... And the opposite story at the other side of the swamp/ glass block , those out first can move faster outside the swamp, so the angle becomes greater.

 

From this , the concept of light moving through a glass block ( towards the normal , on entering . Away from normal when leaving ) .

 

Thus the Teacher said this concept demonstrated how light slowed in glass and thus was refracted.

 

Later a Mathematical formulae was furnished . Giving the ...refractive index = i/r .

 

I remember the story some 50 years later .

 

 

Mike

Edited March 11, 2016 by Mike Smith Cosmos

[ajb]

You are talking about Snell's law, which is of course much older than Snellius. It is true that you can derive this law using wave optics and Fermat's principle of least time.

 

However, I do not think that Snellius was thinking of little soldiers when he wrote down the experimentally observed law. Unless you can point to some evidence.

 

So, I think this analogy is used as a teaching aide and was not fundamental in the development of geometric and physical optics.

[Mike Smith Cosmos]

You are talking about Snell's law, which is of course much older than Snellius. It is true that you can derive this law using wave optics and Fermat's principle of least time.However, I do not think that Snellius was thinking of little soldiers when he wrote down the experimentally observed law. Unless you can point to some evidence.So, I think this analogy is used as a teaching aide and was not fundamental in the development of geometric and physical optics.

Yes I agree , but it shows a use of analogies .

 

Now I need to go one better and use an analogy to devise NEW understanding of a concept .

 

Mike

 

Ps. Give me a moment as I need to deliver tree lopping cuttings to the community tip . ( that's not an analogy )

Edited March 11, 2016 by Mike Smith Cosmos

[ajb]

Yes I agree , but it shows a use of analogies .

As a teaching aide... but what about in cutting edge science?

[geordief]

As a teaching aide... but what about in cutting edge science?

Arguing from personal ignorance (as is appropriate here ) to take the trampoline analogy-which is widely described as flawed . If we physically jump up and down on one we land in a different spot to where we jumped off - depending on the curvature of the trampoline and our speed or momentum.

 

Is there anything in general relativity that corresponds -or could correspond -to that displacement?

 

If there was it might show that I (with help from someone else) could learn something by using an analogy .(even though the theory was already formed)

Edited March 11, 2016 by geordief

[ajb]

Is there anything in general relativity that corresponds -or could correspond -to that displacement?

In this analogy, you cannot leave the surface of the trampoline. Otherwise you are somehow leaving space-time, which does not make sense in the context of standard general relativity.

[geordief]

Ok (it was a very wild stab) .

 

Is one difference between what I was aiming at(trying to conjure up) and "cutting edge science" the fact that the only "teacher" available to them is reality itself (experimentation and interpretation ) ?

 

Edit : I seem to be going off topic now .I will give it a rest.

Edited March 11, 2016 by geordief

[ajb]

Is one difference between what I was aiming at(trying to conjure up) and "cutting edge science" the fact that the only "teacher" available to them is reality itself (experimentation and interpretation ) ?

I guess all that I mean is that the answer is not known from the start. That is you cannot look up the answer in a book. For example, Snell's law and the marching soldiers is an analogy (and not a great one) that was developed as a teaching aide. The formalism was known before the analogy.

 

I think that analogies have been useful in developing some theories, but they are also inherently misleading and must be handled with care.

 

For example, Galileo suggested that the four moons of Jupiter were analogous to the solar system understood as the Copernican model. But without a theory if gravity he could not say any more.

 

Kepler tried to use analogies such as nested spheres in the pythagorean solids to develop a theory of planetary motion. This was not much help and his now famous laws were written down mathematically directly from observations.

 

The luminiferous aether was conceived as an analogy between material waves and light. This really hindered our understanding of light and even today we still hear about it.

 

The Bohr model of the atom comes from an analogy between the solar system and atoms. This model captures some features of what we see, but really it is ad hoc and fails drastically.

[Strange]

Ok (it was a very wild stab)

 

But it highlights one of the problems with Mike's approach (and one that we often see on fourms), where people take an analogy like the "rubber sheet" and then extrapolate wildly from it, as if it were the actual model.

 

So people ask things like "what is space-time made of" or "can you tear space-time" or "what is pulling things down on the rubber sheet of not gravity" (and sometimes, "therefore GR is a circular argument and must be wrong").

[Mike Smith Cosmos]

I think one can gain insight into new ideas if we can take the idea of going to see your friend who has just done some extension on his/ her house . And you are just embarking on an extension.

Here the friends house is like a sort of analogy . You have no intention of living with them , and there are things you would never do . But that idea about the ,.......raised bedroom , now that could dork with us...

 

So with a carefully chosen analogy we might make discoveries that we would not otherwise make .

 

 

I think I can give an example of a discovery not yet put into practice .

 

 

It is to do with the human body and the u.k. Road system .

 

I had often wondered why they are always digging up the roads . Having just surfaced them , blow me a month later they dig it up and lay some fibre optic cables. Now the surface is all bumpy. Why ?

 

Well because it's the only way .the roads are the common conduit system for the country . All services , or most . Follow the roads .

 

The analogous system is the conduit system around the human body . Why do they go the way they do? Because they have to.

 

Now the human body has been going a long time . So is there anything we can copy to make our road systems improved?

 

I think there are a few discoveries waiting to happen there ! All from an analogy !

 

Mike

Edited March 11, 2016 by Mike Smith Cosmos

[Strange]

Arguing from personal ignorance (as is appropriate here ) to take the trampoline analogy-which is widely described as flawed . If we physically jump up and down on one we land in a different spot to where we jumped off - depending on the curvature of the trampoline and our speed or momentum.

 

XKCD is (as always) ahead of you. I hadn't seen this one before:

I think one can gain insight into new ideas if we can take the idea of going to see your friend who has just done some extension on his/ her house . And you are just embarking on an extension.

Here the friends house is like a sort of analogy . You have no intention of living with them , and there are things you would never do . But that idea about the ,.......raised bedroom , now that could dork with us...

 

I'm not sure how you can relate this analogy to science, though.

[ajb]

So with a carefully chosen analogy we might make discoveries that we would not otherwise make .

I do not think anyone would exactly disagree with you on this. What you have said is of course quite loose. We do have, and I have given some examples from history where analogies were used. I also warned that they can be misleading.

[Mike Smith Cosmos]

I do not think anyone would exactly disagree with you on this. What you have said is of course quite loose. We do have, and I have given some examples from history where analogies were used. I also warned that they can be misleading.

I bet you I can look through the human body and make an immediate discovery , which if applied would improve the U.k. National transport system . Just by using the analogy of the human body distribution and collection system .

 

Now there is a wager!

 

Mike

Edited March 11, 2016 by Mike Smith Cosmos

[Strange]

I bet you I can look through the human body and make an immediate discovery , which if applied would improve the U.k. National transport system . Just by using the analogy of the human body distribution and collection system .

 

https://en.wikipedia.org/wiki/Biomimetics

 

No one is saying that you can't use analogies for inspiration. Just that they are of limited value, beyond getting you started. The same could be said about taking a shower: that is where many people get their ideas, but you can't replace science with showering (or analogies).

[Phi for All]

!

Moderator Note

Four more pages on this topic, and all agree that analogies have limited but definable use in science. Beyond that, we risk stretching the point into unrecognizableness.

 

Arguing further about this doesn't seem productive. Beyond the above, subjectivity increases and spoils any efficacy you might realize. Please don't bring this up again, MSC, it's not a discussion we need so many pages about.