Most visitors are first drawn to the grass in Tomas Saraceno's show. It's not just any grass; it's real grass that's growing on a cluster of metallic balloons suspended in mid-air.
"Ah, here, it's turning on the water right now," says Saraceno.
A set of sprinklers kicks on to water the grass. To Tomas Saraceno, what's important is not the grass on the balloons, although it is very cool.
He's more interested in, what he calls, the feedback loop. This sculpture is an ecosystem with the grass in the gallery watered by the sprinklers powered by a wind turbine outside on the Walker patio.
"There will be no wind, the garden will die, things like that, right?" he says.
Saraceno truly is a Renaissance man and his work is about connection. He draws people in through dramatic pieces, but then offers more to those prepared to delve a little deeper.
For example, the grass covered balloons are held together in a rigid harness. It's like a three dimensional bicycle wheel. Saraceno's got a patent for it, and he's got big plans for airships.
"It's the sort of innovation of how we might later possibly build lighter than air vehicles," he says.
Another tall balloon structure is a prototype for what could be a floating building of the future. Saraceno has already built a larger one, some four stories high. This summer he's taking the ideas to what he's calling a Space Camp run by NASA.
"And for two and a half months I will be in contact with someone who will be enthusiastic and build it up and see how far we can get," he smiles.
Last year Saraceno demonstrated how big his ideas can become with his Museo Aero Solar. It's a huge solar balloon the size of a house made from recycled shopping bags, which he inflated at the Walker in October.
At the back of the show is a huge mural he has created which is a whimsical depiction of a possible floating city of the future. It's part Victorian etching and part scientific drawing. Walker associate curator Yasmil Raymond says in a time of hyper-specialization in art, Saraceno is comfortable in many different worlds.
"He is not only going back and forth between science and other fields, like engineering and physics," she says. "But within art he is moving loosely through different media, from photography to drawing and sculpture."
Then Raymond returns to the importance of connection between people and things in Saraceno's work.
She points to the web of guy lines holding the sculptures in place. They make it hard to walk though the gallery with another person. This is deliberate. You have to be aware so neither of you trip.
She says it's the same with walking through the balloon buildings, where the soft floors sag underfoot like trampolines.
"Your weight affects the weight or the location of the other person," she says. "Because either by pressure or the air that is released you will be interfering with the stability of the other person."
Real floating cities may be far in the future. Saraceno certainly hasn't found all the answers.
Yet he hopes other people will help fill in the blanks. He quotes the Russian film director Andrei Tarkovsky about how he just told part of a story in his movies.
"Like Tarkovsky was always saying, 'I will only give you 50 percent, the other 50 percent you have to build it by yourself.' Without your imagination we will not do anything."
To help jump start the process Saraceno is giving out instructions at the Walker show. He says if you follow what he calls the "59 simple steps" you can build a solar-powered balloon out of trash bags which will lift an adult off the ground.