The the "true vacuum" spreads at the speed of light. It could be moving towards us and we would never know. Any signal revealing the edge would arrive simultaneously with the event. Shades of the Jame Blish "Cities in Flight" series.
Compared to the clowns that have run Yahoo to date, Marissa Mayer is a breath of fresh air. Yahoo needs a strategic person on top. Yahoo ran in front of the crowd with many features that were not monetized. Best financial section in the early days but they hid the link on the home page, moved it around and almost seemed embarrassed about it. In late 1990's every VC I knew went to Yahoo fist for news. They had an outstanding online merchant system again late 1990's that anyone could use to set up web sales. They even took care of setting the credit card merchant account details. I was blown away on how many early online sales were powered by their system. They even had phone support, all for less than $20/month. They were more that five years ahead of Amazon. If they could of put all those companies under their banner as Amazon now does that one feature alone could have made the company. If Ms. Mayer can focus on one to two areas, get good people to help her execute, Yahoo could come back. There are still many smart technical people at Yahoo. I wish her the best of luck. With Alta Vista (DEC) and Excite ancient history, it would be nice to have Yahoo along with Apple as two early pioneers still around.