Google search engine infrastructure dubbed as Caffeine is down, a possible come back is set this afternoon.

“DON’T PANIC”, said Matt Cutts, Principal Engineer of Google.

Google has just pull down its Caffeine sandbox flag for a server upgrades. The server where Caffeine was hosted is undergoing upgrades of power components.

Google revealed the Caffeine search engine this week as a preview of what they called a secret project search engine infrastructure.

There is no difference between Caffeine search engine infrastructure and the ongoing live Google Search engine when it comes to User Interface although there are some changes in the search results.

Google focus more on the infrastructure of the search engine and rewrite the parts that don’t scale well to make them more robust, more elegant, or faster.

For now, Caffeine is not available for now but Cutts promise that it well be back today.

We’re shooting to bring the sandbox back up by late Thursday afternoon or evening Pacific Time, Cutts said.

In addition, Caffeine is also not available for international version of Google Search Engine neither a Mobile version because the unveiling of the Caffeine is just a preview.