Here’s the lecture, which was given in 2004 at the University of Colorado, Boulder.

This lecture might be a little advanced for beginners, but if you stretch your mind first, you shouldn’t tear anything. (Note: standard disclaimers apply if you do tear something!)

The description of the video states:

This is quite simply one of the best lectures William Lane Craig (a philosopher of science) has given. Craig explores the origins of the universe. He argues for a beginning of the universe, while refuting scientific models like the Steady State Theory, the Oscillating Theory, Quantum Vacuum Fluctuation Model, Chaotic Inflationary Theory, Quantum Gravity Theory, String Theory, M-Theory and Cyclic Ekpyrotic Theory.

And here is the description of the lecture from Reasonable Faith:

A Templeton Foundation lecture at the University of Colorado, Boulder, laying out the case from contemporary cosmology for the beginning of the universe and its theological implications. Includes a lengthy Q & A period which features previous critics and debate opponents of Dr. Craig who were in attendance, including Michael Tooley, Victor Stenger, and Arnold Guminski.

Craig has previously debated famous atheists Stenger and Tooley previously. And they both asked him questions in the Q&A time of this lecture. Imagine – having laid out your entire case to two people who have debated you before and who know your arguments well. What did they ask Craig, and how did he respond?

The scientific evidence

The Big Bang cosmology that Dr. Craig presents is the standard model for how the universe came into being. It is a theory based on six lines of experimental evidence.

Scientific evidence:

1. Einstein’s theory of general relativity (GTR)
2. the red-shifting of light from distant galaxies implies an expanding universe
3. the cosmic background radiation (which also disproves the oscillating model of the universe)
4. the second law of thermodynamics applied to star formation theory
5. hydrogen-helium abundance predictions
6. radioactive element abundance predictions

If you are looking for some detail on these evidences, here’s a re-cap of the three main evidences for the Big Bang cosmology from Caltech. (Numbers 2, 3 and 5 from the list above)

Excerpt:

Until the early 1900s, most people had assumed that the universe was fixed in size. New possibilities opened up in 1915, when Einstein formulated his famous general relativity theory that describes the nature of space, time, and gravity. This theory allows for expansion or contraction of the fabric of space. In 1917, astronomer Willem de Sitter applied this theory to the entire universe and boldly went on to show that the universe could be expanding. Aleksandr Friedmann, a mathematician, reached the same conclusion in a more general way in 1922, as did Georges Lemaître, a cosmologist and a Jesuit, in 1927. This step was revolutionary since the accepted view at the time was that the universe was static in size. Tracing back this expanding universe, Lemaître imagined all matter initially contained in a tiny universe and then exploding. These thoughts introduced amazing new possibilities for the universe, but were independent of observation at that time.

[…]Three main observational results over the past century led astronomers to become certain that the universe began with the big bang. First, they found out that the universe is expanding—meaning that the separations between galaxies are becoming larger and larger. This led them to deduce that everything used to be extremely close together before some kind of explosion. Second, the big bang perfectly explains the abundance of helium and other nuclei like deuterium (an isotope of hydrogen) in the universe. A hot, dense, and expanding environment at the beginning could produce these nuclei in the abundance we observe today. Third, astronomers could actually observe the cosmic background radiation—the afterglow of the explosion—from every direction in the universe. This last evidence so conclusively confirmed the theory of the universe’s beginning that Stephen Hawking said, “It is the discovery of the century, if not of all time.”

It’s probably a good idea to be familiar with these if you are presenting this argument, because experimental science is a reliable way of knowing about reality.

Published research paper

This lecture by Dr. Craig is based on a research paper published in an astrophysics journal, and was delivered to an audience of students and faculty, including atheist physicist Victor Stenger and prominent atheist philosopher Michael Tooley, at the University of Colorado at Boulder.

Here’s the peer-reviewed article that the lecture is based on.

Here’s the abstract:

Both cosmology and philosophy trace their roots to the wonder felt by the ancient Greeks as they contemplated the universe. The ultimate question remains why the universe exists rather than nothing. This question led Leibniz to postulate the existence of a metaphysically necessary being, which he identified as God. Leibniz’s critics, however, disputed this identification, claiming that the space-time universe itself may be the metaphysically necessary being. The discovery during this century that the universe began to exist, however, calls into question the universe’s status as metaphysically necessary, since any necessary being must be eternal in its existence. Although various cosmogonic models claiming to avert the beginning of the universe predicted by the standard model have been and continue to be offered, no model involving an eternal universe has proved as plausible as the standard model. Unless we are to assert that the universe simply sprang into being uncaused out of nothing, we are thus led to Leibniz’s conclusion. Several objections to inferring a supernatural cause of the origin of the universe are considered and found to be unsound.

The whole text of the article is posted online here.

If you want something to post on your Twitter or Facebook that is much shorter than this lecture, then you should check out this quick 4-minute explanation of the kalam argument.