How imagination is form... How is it helpful in learning mechanism... How can we estimate one action before taking ours.... How can we implement imagination in machines.....
In my opinion, imaginations are just the result of various combinations. You can't imagine something you have never seen or heard of. On a whole imagination may seem to be coming out of the blue, but deep inside it's not. It's just composed of smaller bits of known or sensed things arranged in different manner(different or all combinations). Think of a kaleidoscope and how does it work. To make machines imagine, prepare linear model with a set of input states, so that every time it gives you expected output states. Add some non linearity to the model, add some chaos and then see how the system predicts the output states. I just gave an example of designing imagination models.
I'm sorry to say one thing about your comments u made. "You can't imagine something you have never seen or heard of"- this statement is not true at all, if its true then never new things got invented or discovered in the world or any new ideas can be generated.
I agree that a major part of imagination is born in listening to and reading stories, and then being asked to tell one's own stories. I spent many years teaching art and living among artists. Another part of imagination comes from interaction with form and material...and the structures present in the world, having the opportunity to manipulate them, and play. Most kids are naturally curious if adults don't kill the impulse in them. Actually, I also think the brain is hardwired for imagination, wonder, play, manual manipulation, visual manipulation, auditory manipulation, and all you have to do is give it a safe place to live and some loving, joyful encouragement.
Your question is an interesting one and you can trace its genesis to the esoteric sciences or spiritual and psychology texts. Indian spiritual texts have dealt in great depth with the inner working of the mind or the psyche. Carl Jung was also deeply influenced by the ancient Indic texts. This question is a study of psychology as well as spirituality. Naively speaking and (subject to debate:-)),the differentiation can be interpreted as follows - Thoughts are the deliberate purposeful activities of the human mind whereas imagination is not based on any rationale. The mind is always active, even when one is not consciously thinking, and when these mental vibrations develop critical mass and some triggering event occurs, they thrust themselves to the forefront and manifest before us. An example would be a person buying a lottery "thinking" that he has a chance to win. However, before the results are declared, he starts to "imagine" or project what-if he were to win and then cars, palaces, luxuries, retirement... all flash before him. Once these desire pattern subside he realizes he is still holding the lottery in his hand. So, imaginations typically have no purposeful action associated with them and are a collage from one has assimilated over multiple lifetimes - consciously and subconsciously - and the ability of the mind to take 2 pieces of information and create a new interpretation independent of logic and method of reason would fall in the category of imagination.
Imagination in a machine would have to be synthetic reasoning. Creative imagination frequently involves taking things that do not necessarily have any relationship to one another and seeing what will happen when they form a relationship. And I would say that most imagination in the arts is purposive. What about Tessla who imagined whole machines/inventions and tested them to see if they would work i his mind before committing anything to paper?
Imagination is a mental manipulation of arranging and rearranging of thoughts. Let's us they are related. However, this manipulation of thoughts take an individual to a different spectrum where are no limits. One can allow their imagination to move towards positive/negative, functional/dysfunctional, and healthy/unhealthy thinking. Imagination either can exaggerate or downplay actual situations. I am basing it from the field of counseling psychology.
So then you need to get the machine to play. What if you give it a topic and a set of words, even the scrambled words of a poet's poems--or to make it harder: take the words of five poems and scramble them or put them in an alphabetical list, give the machine topic, and see if it can make good poetry...after you teach it something about poetry. Or give it game elements and see if it can create a game.