Google's not exactly working against the echo chamber problem, and I think that's because to do so would be to work against its own reason for existing. There are two goals here that are fundamentally at odds with each other:
1) Finding what you're looking for.
2) Finding a new perspective on something.
A search engine's job is to address the first challenge: finding something that the user is looking for. The search engine might end up serving both needs if they're looking for a new perspective on something, but if these two goals ever come into conflict with each other the search engine does (and I would argue it should) choose the first goal. Failing to do so will just lead to people ignoring the results.
Part of the thing with echo chambers is that the search terms themselves can be indicative of a particular bubble. For example, there's a difference in the people that refer to the Bureau of Alcohol, Tobacco, and Firearms by the official initialism, "ATF", and those that use "BATF". There's a strong antigun control bent to the `"BATF" guns` query, compared to the `"ATF" guns` query.
If you're indexing forums or social media, the same site is going to give back the bubbled responses, possibly without the person even being aware they're in a bubble.
Kind of like when searching for "jew" on Google led to antisemitic websites, that's because jews usually prefer the term "jewish".
Interestingly, back then, Google was big on neutrality and refused to do anything, stating that it reflected the way people used the word. It was finally addressed using "Google bombing" techniques. Something that Google didn't care much about back them because of its low impact.
Google's not exactly working against the echo chamber problem, and I think that's because to do so would be to work against its own reason for existing. There are two goals here that are fundamentally at odds with each other:
1) Finding what you're looking for.
2) Finding a new perspective on something.
A search engine's job is to address the first challenge: finding something that the user is looking for. The search engine might end up serving both needs if they're looking for a new perspective on something, but if these two goals ever come into conflict with each other the search engine does (and I would argue it should) choose the first goal. Failing to do so will just lead to people ignoring the results.