Elasticsearch vs. Google

Hi, I am looking at Elasticsearch currently. Looks like a great search engine tool. I was wondering - what are its performance metrics relative to established players like Google? Like it uses Okapi BM25 algorithm, how does that measure up against Google's PageRank? Is the quality and relevance of search results it offers at par with what Google offers? And secondly, what about the performance? Google handles 5 billion queries per day, with natural peak load scenarios like sports events, or other bid incidents like elections. is Elasticsearch capable of scaling to this level, with the right combination of sharding, distribution and indexing?