go - nil slice when passed as interface is not nil! Why? (golang)

Question

See this playground: http://play.golang.org/p/nWHmlw1W01

package main

import "fmt"

func main() {
    var i []int = nil
    yes(i) // output: true
    no(i)  // output: false
}

func yes(thing []int) {
    fmt.Println(thing == nil)
}

func no(thing interface{}) {
    fmt.Println(thing == nil)
}

Why the difference in output between the two functions?

Answer 1

Waitting for answers