JERSEY CITY — Erno Rubik interlaces his fingers, thinks for a moment and then explains, “I wanted to convince human beings that there are no unsolvable problems.” Then he smiles and adds, “Maybe it’s not exactly like that, in reality. But if we don’t have the courage to venture towards the unknown, then surely we’ll never get anywhere.”

Forty years ago, in the spring of 1974, the unknown for Erno Rubik was a cube made of 54 colored squares. Rubik, a Hungarian-born architect and professor, thought of it as a puzzle to keep his students busy: There are 43,252,003,274,489,856,000 possible combinations but only one right solution.

It wasn’t long before this academic gag became the best-selling toy in the world — an estimated 2.5 billion cubes have been made, not including the many counterfeits.

For some it has become a mania, to the point of international competitions to see who could solve it the fastest. The current record stands at 5.5 seconds.

It’s truly an icon of our time. When Edward Snowden went to meet journalists Glenn Greenwald and Laura Poitras in the Hong Kong restaurant to leak the NSA documents, he told them they’d recognize him because he’d be holding a Rubik’s Cube.

The legendary puzzle’s 40th birthday was recently celebrated at the Liberty Science Center in Jersey City, NJ, with an exhibit that included an 18-carat gold cube worth $2.5 million, as well as a robot able to solve the puzzle in a snap.

It’s here, on the terrace that looks towards the Statue of Liberty, that I have my appointment with the 70-year-old Rubik, with plenty of questions to ask — and problems to solve.

LA STAMPA: What first gave you the idea to make the cube?
RUBIK: There’s not just one response to that. I have always been fascinated by the capabilities of the human mind to solve problems. Think back to the Ancient Greeks, who were successfully able to determine the diameter of the Earth without any satellites or any modern equipment. I liked technology and the gadgets that I learned about from my father, who was an engineer. So I created something that trains the mind to solve problems, with the belief that it was possible to solve them.

Could you imagine it would turn into such a success?
Absolutely not. I often ask myself: What is success? Making money? Becoming famous? Yes, but it’s not enough. For me, it means finding inner peace, and doing things that keep yourself interested.

Why do you think, 40 years later, millions of people are still interested in playing with this puzzle?
At the heart of it, it’s a small model of the universe, where simple elements combine to become very complicated forms. At the beginning, you think that the only way to solve the cube is to go back to where you started from, but it’s not like that. There’s only one solution, but there are an infinite amount of ways to get there, and that’s the fascination of life. Having the courage to explore the unknown.

You are currently working in video game development, and run Rubik Stúdió, which designs furniture and games. In a time when children and adults alike are surrounded by technology, how can your cube still be relevant?
The cube finds itself at the confines of many things: science, art, as well as the digital and analogue worlds. I think that it represents an anticipation of the digital revolution.

What do you think of the way technology is taking over our everyday lives?Computers aren’t gods, but just instruments that help us reach our goals. The border between the real and the virtual is very ephemeral. When we dream, our dreams seem real, but when we then wake up we know that we’re not actually able to fly. When it comes to computers, though, we can actually operate computers that truly allow us to fly. So, this is the aspect of the digital revolution that interests me most: the capability to connect things together. Taking the virtual, and through technology turning it into reality. Solving problems and getting results, responding to the needs of humans, which remains our primary objective. In other worlds, the same reason I invented the cube.