Hi, Sreenath
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I do not dispute that string theory and loop quantum gravity have not as yet been tested and, if this keeps up, they may need to be relegated to the dustbin of useless theories. (But remember that it was many years between the first statement of Einstein's theories and the possibility to measure them; so too was Bell's theorem only much later tested in the lab, and so forth. It may be too early to rule out the possibility to test string theory or loop quantum gravity.) But in any case I would not say that they have not come up with new ideas, which is what you mentioned. Some of the mechanisms in these theories are quite ingenious; whether they are physics or just good fantasy is another question. But good fantasy can also come up with new ideas.
When I said that the use of your definition might be a little awkward in practice even if valid in theory, I meant that physics is couched in terms which are mostly stated as if humans did not come into it: even the observers in relativity do not need to be human, quantum physics deals with changes by energy, not mentioning whether that energy is part of a chain linking it to a human. Physics equations do not need a human in them, allowing them to be used by both Idealists and Materialists. The interpretation as to what the equations mean is another matter. Hence, in measuring for example the entropy of a black hole, one does not put in a chain of equations linking it to the humans who make the measurements of the astronomers from their radio telescopes. You yourself emphasize the link of physics to mathematics, and one generally uses 2+2=4 without explicitly stating that humans invented the plus sign. Yes, it is understood that the link is there, that physics as a human activity (which may be different to the laws of the universe) requires humans, but in practice this link remains implicit, not explicit. Making it explicit would make physics very awkward. This does not mean that it is an invalid philosophical position, though.
I now understand what you meant: I misunderstood your phrase ".... had begun on earth for about a billion years, even prior to the existence of simplest form of life, " to imply that "the existence of simplest form of life" preceded the point of time of a billion years ago, whereas you meant the billion years between the formation of the earth and the beginning of life. My mistake; thanks for explaining this to me.
As far as biology's reduction to physics: this is, at the moment, a matter of belief, since of course right now one cannot carry out this reduction. However, there is nothing to exclude it, and the practice of modern neurobiology rests on the goal of completing this reduction eventually. Indeed, quite a lot about intention in the brain is already known. Your example only rests on your belief that the limitations of our present technology are absolute. Of course, even when the correlation between brain and mind will be perfect, there will still remain the option to say that it is only a correlation, and that they are not the same thing. This is known as the Mind-Body Problem; you can google it for further information.
You are of course free to coin your own definition of evolution; I was merely pointing out that your definition does not coincide with the common definition in modern biology.
The restrictions I had in mind were not akin to those of religion or religious authorities. Rather, I was thinking of the restrictions brought about by quantum physics (you cannot ask what goes on in the "quantum foam") and by mathematical logic (if you use mathematics in which arithmetic can be embedded, then you cannot determine, using the tools of that mathematics, whether your system is consistent; using another system to determine it then merely transfers the problem to your new system).
Perhaps I understood your stance incorrectly, but it appeared to me that you were implying that Reality was deducible from pure mathematics. In Kant's terms, that there are a priori synthetic truths. For this Kant used the example of the statement that a triangle will always contain 180 degrees, which then was shown to be false. That is, a system of pure mathematics alone (I emphasize "alone") cannot explain Reality, because a mathematician can think of another system which will contradict that explanation, and is mathematically just as valid. That does not mean that mathematics is useless: that is, combining mathematics with something else could very well explain reality, but the problem is to figure out what that "something else" is. I don't have the answer to that one.
Best regards, David