The 1989 film Back to the Future II wasn't quite on the money when it predicted we'd have self-tying shoes and flying cars by now.

But in 2018, we do have the very real prospects of space tourism, asteroid mining and terraforming on uninhabitable planets.

So how — and where — should we envisage ourselves in the decades to come?

"I predict that our grandkids will have the ability to honeymoon on the Moon," says world renowned theoretical physicist Michio Kaku.

Physicist Michio Kaku argues that, to ensure our survival, we need to settle on another planet. ( Getty: Dimitrios Kambouris )

It's "only three days away", he says, "so I think that's an easy target".

Professor Kaku says in the near future humans will also colonise Mars — not just because we can, but because we might have to.

Humans need 'a plan B'

He argues that if humans want to stick around, we need a back-up plan — and it needs to be far from the potential threats of Earth.

He says "99.9 per cent of all life forms" become fossils and "disappear off the face of the Earth".

"Look at the dinosaurs," Professor Kaku says.

"The dinosaurs did not have a space program and that's why they are not here today to talk about it."

Sorry, this audio has expired Michio Kaku discusses terraforming Mars, interstellar travel and our destiny beyond Earth.

Professor Kaku, who has authored a book titled The Future of Humanity, says humans are susceptible to the same fate.

"Extinction is the norm," he says.

"We think of Mother Nature as being warm and cuddly, which is partly true. But nature is merciless when it comes to wiping out inefficient life forms."

Professor Kaku says humans need a plan B. ( Unsplash: André Bandarra )

Professor Kaku advocates 'terraforming', the process of creating a habitable environment on another planet.

He believes this could be achieved on Mars by launching solar satellites to the planet, to beam sunlight onto its polar ice caps to begin the process of heating it.

"Once you can raise the temperature of Mars by six degrees, it takes off all by itself. All of a sudden you get a runaway greenhouse effect, and Mars basically terraforms itself," he says.

But he says he's not suggesting humans need to evacuate Earth.

"No-one is talking about leaving the Earth and going to Mars," Professor Kaku says.

"We're talking about a settlement, a self-sustaining settlement on Mars, that's not going to drain the resources of the planet Earth but will give us an insurance policy, a plan B."

Space prices 'dropping like a rock'

To put something — or someone — on Mars costs upwards of $1 million per half-kilogram.

That's prohibitive — but Professor Kaku doesn't expect it to stay that way forever.

He uses the example of The Martian, a film starring Matt Damon. It cost $100 million to make, while the Indian Government sent a probe to Mars for $70 million.

"So a Hollywood movie about going to Mars cost more than actually going to Mars," he says.

And, he says, "prices are dropping like a rock".

'Laser porting' our digital selves

Professor Kaku believes we may one day even gain the capacity to travel through space without even leaving home.

'Laser porting', as he calls it, involves a person's memories and thoughts being digitised in an AI-driven replica. That digital self is then transmitted via laser beam into space.

"In one second you are on the Moon. In 20 minutes you're on Mars and in a few hours you are on Jupiter," he says.

"One day someone in Silicon Valley will digitise everything known about Einstein and put it into a robot with a personality and we will be able to talk to Albert Einstein.

Professor Kaku says in the not-too-distant future we'll be able to chat with the digital incarnations of people like Albert Einstein. ( Getty: Central Press )

"We'll talk to Winston Churchill.

"Libraries will be a library of souls."

Professor Kaku believes laser porting could become a reality for humans within 50 or 100 years — though he argues others might have beaten us to it.

"I'll stick my neck out, I think this already exists," he says.

"I think aliens from outer space ... simply digitise their personality, put it on a laser beam and shoot their consciousness at the speed of light."

Regulating in space

Once the temperature on Mars is lifted by six degrees, the planet will be habitable, Professor Kaku says ( Getty )

Professor Kaku says the possibility of space tourism and colonisation has created major regulatory gaps that need to be addressed now.

"We need a new outer space treaty to regulate traffic as we go into outer space, and we have to regulate private enterprise," he says.

The Outer Space Treaty of 1967 determines that nuclear weapons shouldn't be put into space and nation states cannot claim Mars or the Moon.

But Professor Kaku says it's not enough.

"The problem is, in 1969, who would have thought that a private individual using his own piggy bank, using his own bank account, can create a Moon rocket fully capable of reaching the Moon with colonists?

"Elon Musk is selling tickets — tickets to be on the first commercial venture to the Moon, and a Japanese billionaire by the name of [Yusaku] Maezawa bought out the entire rocket.

"So this is now well within economic feasibility to have tourists go to the Moon."

There are growing — and competing — interests at stake, he says: China is vying to go to the Moon, Japan and India have already sent missions there, and even Google wants to mine asteroids.

"We need new regulations, just like we needed regulations in California when the Gold Rush happened there and we had thousands of miners clashing with each other to hunt for gold," Professor Kaku says.

"We are not the only game in town anymore."