I hope that this question doesn't seem too naieve or obtuse, but based on the statement that all matter present in today's universe was present at the time of the big bang, then at the very first instant, matter began to expand.<br /><br />At the very start of expansion, with all matter only the tiniest distance apart, gravity was at work. As the new universe cooled, elementary particles started to form atoms, blah, blah, blah...<br /><br />Using this as a premise, gravity has always been there. Its effects have been here since "bang +1" so to speak. So how can we even measure the propogation of gravity to any degree of surety?<br /><br /><br /><br /><br /><br /><br /> <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>