Does Google have a separate mobile index?

[dethfire]

Does Google have a separate mobile and desktop index? My concern is that if I shift some content to a sidebar that on mobile is hidden, will that hurt me in Google mobile?

[goodroi]

I wouldn't say it has a separate mobile index, more like a separate ranking criteria for mobile. Right now the ranking criteria is very similar with desktop search but Google is moving to making it a more unique. I would be careful in making content not visible to mobile users. Not even thinking how this hidden content might impact Google rankings, I wouldn't do it because it could take away from the user experience. Unhappy users tend to leave and never come back which isn't good for my conversion rate.

[aakk9999]

The question is interesting right now especially after the latest announcement by Google where mobile friendlyness is to be added as a ranking signal.

We are discussing this here: Google To Expand Mobile Friendliness As A Ranking Signal [webmasterworld.com]

So if it is not a separate index then as a minimum it should be some kind of layer/filter on top of the current index.