Astronomers may find aliens in the coming decades but how will they know their intentions?

While humans could be ready to welcome alien life discovery, futurist Michio Kaku believes we have a lot of work to do in order to prepare for the first big conversation with extra-terrestrials.

Kaku, who is a theoretical physicist and populariser of science, thinks we'll find alien life by detecting radio signals within this century, but talking and getting to know a whole new species could be difficult, especially with the element of distance.

"They could be tens of light years away," he said in a recent AMA (ask me anything) session on Reddit.

However, Kaku believes that this distance would be an opportunity for us to develop sophisticated techniques to understand their language, level of technology, and most importantly intentions. "Are they expansive and aggressive, or peaceful?," he added.

While most sci-fi movies depict alien visitors as a threat to humanity or something that brings chaos, panic and hysteria among people, the physicist thinks the species would mostly be peaceful.

They could land on the White House lawn to announce their existence, he added. "But I think that is unlikely since we would be like forest animals to them, i.e. not worth communicating with."

However, the futurist reiterates that even if they don't hate us, aliens could be a danger to human life if we get in their way. "In the same way that a developer is a threat to forest animals because he can pave the first, the danger there is from someone who sees that we are just in the way."

Apart from alien life, Kaku addressed questions revolving around interplanetary travel and AI-backed robots during the AMA session. He stressed that robots of the future may think about killing humans and we'll have to develop appropriate fail-safe mechanisms and chips to keep them from going rogue.