[Lord of Angmar]

well, it is true that there was a lot of technological advancement that should theoretically of happened in the time between the first age and the fourth

I beg to differ. The advancements made between the First and Fourth Age were remarkable. On a timescale compared to our own, their progress was unbelievable. Humans have been around thousands of years, far longer than the number represented in the First through Fourth Age, and only in the past two milleniums have we made any real technological advances that can be measured today (some would argue against me, and cite the pyramids, but that was still a relatively well-developed society compared with the societies of Middle Earth).

The theory is that the elves and elf-friends were in fact the blockers of development in Middle Earth. It is common knowledge that the elves were the fairest, long lived and wisest but they were always the same. Did the elves ever represent any change? No.

Tolkien's beliefs about the natural world were such that change was not as good as preservation. Tolkien believed that staying close to the natural world and preserving its beauty was far more important than technological advancement. In fact, he was a stern advocate of technological 'advancement' and industrialization, which he strongly believes (and I agree with him) will lead to the end of the human race and the rape of the natural world. If Men were imbued with the powers to change and advance technologically, I believe this power would be more firmly rooted in the fact that Morgoth, who changed Iluvatar's plans and who first developed machines and engines of war, had a great influence on men at and after their awakening. A part of Morgoth went into men, so that they could never sit understand nature as the Elves did and could never sit fully contented in time of peace.

You may say that Elves are 'stuck in their ways', and this is true to an extent, but this is because their nature itself has created a kinship and bond with nature for them which they (wisely) feel would be better left undisturbed.

traditionally war has, terribly enough, often meant an acceleration in the development of both society and technology. If we take a step further in the develpoment of men

True enough, but is this development really positive at all? Certainly World War II led to the advancement in the nuclear arms race, which has altered society drastically but has not had any desirable effect. WWII and Vietnam set the precedent for testing new and more powerful weaponry on our enemies each time we engage them. None of these wars significantly advanced society as a whole, nor could the positives of these advancements outweigh the negatives.

all the time they waned. That is, I think due to that they had so close relations with the elves

An absurd notion, really. Gondor waned as their relationship with the elves decreased, which it did drastically after the Last Alliance (when Gondor was at its most powerful). Need I remind you that the Numenoreans learned much if not all of their craft from the Elves of Eressea?

The Noldor and the Teleri certainly made great 'advancements', in the fields of gemcraft and shipbuilding, respectively. The Noldor it were who wraught the most fabulous gem creations ever, not to mention extremely strong swords and mail. The Teleri were certainly masters of shipbuilding, and their ships were completely unrivaled by men in later days who (gasp) did not have relations with the Elves.

As soon as men were distanced from elves, they went on, from the old

Tell me, what great accomplishments have Men made since the fading of the Elves (assuming, of course, that Middle Earth is real history and we are talking about Men as humans now who are descended from the men of Middle Earth)? Men are destroyers of the natural world, who have made no advancements in living, really. Elves were the embodiment of serenity, and their oneness with nature was idyllic in Tolkien's world. Tolkien thought of men as slightly corrupted beings, who could not help but try to force their ways on the natural world, what we now call 'advancement.' The Elves were the wisest and most pure, and it was they who most fully understood the workings of the natural world.