On Tuesday, Google's search engine added a new feature that's being called the "most radical transformation ever" and "a very big deal." With Google's "Search, Plus Your World," the search engine will not only yield search results from the public internet, it will also feature results from a user's Google+ network. Search for "Tahiti," for instance, and you'll not only be treated to links to the islands' tourism site and travel guides, you'll also, under a separate header, be offered pictures of that Bora Bora vacation someone in your Google+ network took. Why is this such a big deal? Four reasons:

1. It's a bold move against Facebook
This "move to more thoroughly integrate Google+ into every aspect of Google's functionality is a clear effort by Google to compete head-on with Facebook's own social search efforts," says Sean Gallagher at ARS Technica. "By making social networking part of Google's highest-profile profitable product [search], the company is clearly making a big bet on the ability of Google+ to fend off loss of traffic and ad revenue to Facebook."

2. It could be bad for Google
In trying to maximize the potential of both Google Search and Google+ together, Google could hurt its core search tool, says Alexis Madrigal at The Atlantic. While being able to search through social media content is "a great addition to search," Google runs the risk of losing its search comprehensiveness by integrating with Google+. It's not searching all social networks, just its own. Google's goal has long been to "organize the world's information and make it universally accessible and useful," not just to "organize Google's information." Twitter is already up in arms, fearing that it will be harder to find pertinent Twitter posts with Google Search.

3. It's the beginning of Google's grand plan
This shows how big and broad Google is thinking, says Jolie O'Dell at VentureBeat. It doesn't intend for Google+ to be a "mere social network." Instead, Google team members have said the company plans "to bring social information into everything you do on the web, from shopping to search to email and beyond." Someday soon, you'll likely see Google+ results in Google Shopping, Google Maps, and Google News, not just in Google Search. This is only the beginning.

4. The feds aren't going to like it
"A privacy watchdog group probably will complain to the U.S. Federal Trade Commission" that this raises privacy and antitrust issues, says Jessica Guynn in the Los Angeles Times. This adds to growing concerns that Google is using its position as the dominant search engine to promote its other products and give it an unfair edge over Facebook. "Google is an entrenched player trying to fight off its challenger Facebook by using its market dominance in a separate sector," says the executive director of the Electronic Privacy Information Center, Marc Rotenberg. "I think that should trouble people."