Mike, my understanding is that the new super collider is intended to permit experiments that go back a bit before the Big Bang. However, the issue you raise will remain, that being; What may have happened before the reach of human understanding?

I don't think a proper response is "anything". Rather it is "we can't reliably speculate".

Regarding dimensions, we percieve time and space to be observable. There are some proposed understandings that posit additional dimensions. My understanding is that the meaning of "matter" is profoundly different in the context of those additional dimensions.

Regarding an infinite regression of events, my understanding is that in the pre-Big Bang universe causality becomes confusing due to the collision of quantum mechanical and relativistic effects ... think about the entire obserable universe being condensed into a volume of a large citrus fruit ... that was the state of things at the moment the Big Bang. There would be no electrons orbiting atomic nuclei. The medium of "space" in which light will eventually propagate does not yet exist. In this realm the question of what came first; the cause of the effect; is moot (at least locally).

The short version; the universe we understand was manifested from a prior state undergoing an expansion of space and time. There is no need for a universal origin.

Agnosticism is the philosophical view that the truth value of certain claims — particularly metaphysical claims regarding theology, afterlife or the existence of deities, ghosts, or even ultimate reality — is unknown or, depending on the form of agnosticism, inherently impossible to prove or disprove.

Atheism, as an explicit position, can be either the affirmation of belief in the nonexistence of a god or gods,[1] or the rejection of theism.[2] It is also[3] defined more broadly as an absence of belief in deities, or nontheism.

In my opinion, everyone is an agnostic. None of use have knowledge of God's existence. Those who believe they have knowledge of God(s) either don't grasp the point or are deluded ... at the same time those who assert there is no God are making a significantly weaker claim.

I'll explain, theism makes a specific positive assertion. That assertion is; "God(s) exist." Atheism varies from the absence of a theistic assertion to the negative assertion that no God (s) exist.

The difference between positive and negative assertions is subtle, but important. A positive assertion is a claim that something exists, or is true. A negative assertion is a claim that something does not exist, or is not true. In principle, only positive assertions are used in proofs and only positive assertions can be proven.

This may appear overly pedantic, but I'm not the only one ;-)

In any event, I liked Laci's video. However, negative assertions do not carry the same burden as positive assertions.