Two abstract responses to the WTC/9/11:
"Light, Marshall McLuhan reminded us, is a medium. Indeed, in his influential book "Understanding Media," the Canadian thinker devoted his chapter on architecture to developing that idea. Light is a "pure" communication medium whose power to shape environments is independent of content. In artificial form, light reshaped the boundaries of buildings and entire cities. We encounter that form in its purest state at night, when gazing up at a skyline, or gazing down from an airplane window at suburban sprawl. But, perhaps because of its neutrality, light can easily absorb a range of ideological connotations, meanings that may or may not be intended by those who exploit its functional and formal qualities."
Herbert Muschamp on Tribute In Light [registration (free) required]
"The luminous columns shining into the heavens surely transcend any constructed memorial that could be devised ... The 'Tribute in Light' is not to be seen, but rather it is to be felt."
From letters to the New York Times [registration (free) required]
And in sound, the Sonic Memorial.