With the recent announcement that Google would index HTTPS versions of web content over HTTP versions, there was a serious worry that the authority HTTP content had would be lost. After all, if another, distinct version of the content were indexed over the already existing, authoritative version, the implication is that the authoritative version’s authority would be overridden. The younger content being privileged means the older content, and all of the weight it carried, would be cast aside.
Fortunately, Google foresaw this and has confirmed that there will be no link authority lost in this way. An HTTPS version of a piece of content will carry the same authority as the HTTP version.
The lost link authority would play havoc with site rankings, and discourage people from moving their authoritative content to HTTPS– a move that Google is encouraging for user security (and thus user experience) reasons. Google’s foresight protects everyone– users, webmasters, Google themselves, and your humble SEO professionals.