Impossible? Scientists say no. Improbable or uneconomical? Maybe.

As any entrepreneur, disruptor or innovator will tell you, there are always naysayers. And it didn’t take long for experts to chime in with their opinions on the topic of Elon Musk’s newly released Hyperloop design.

Interestingly, most of the criticism regarding the Hyperloop was not related to the science behind the project, but rather to the talent and the funds necessary to make it a reality.

John Hansman, a professor of aeronautics and astronautics at MIT, told the MIT Technology Review that it’s “far-fetched” but not impossible.

“I don’t see anything that violates fundamental laws of physics. … [But] it would be enormously expensive. And I think there are a huge number of technical challenges with the vehicle. … My questions aren’t could you do it, but could you do it in a way that makes sense from an energy efficiency standpoint and makes sense from an economic standpoint.”

Joseph Sussman, a professor of civil and environmental engineering at MIT, questioned the ability to execute, not the technology.

“We’re behind the Japanese, the French, and everyone else. Given our inability to put together the package to do high-speed rail, which is proven technology, it’s hard to see how a chancy solution–given that it’s never been implemented–would fare.”

David B. Clark, director of the University of Tennessee, Knoxville’s Center for Transportation Research, told Fast Company that he was impressed with the level of detail, but not sold.

“It does appear well-thought out. Obviously, there is nothing like this in the world today, so the feasibility is entirely unknown.”

Rod Diridon, director of Mineta Transportation, previously chairman of the California High-Speed Rail Authority Board, pointed to funding issues–and Musk’s ability to surmount them.

“It’s going to take a tremendous amount of funding to build a demonstration project, and there aren’t many deep-pocketed individuals other than Mr. Musk to do it.”

Zafar Khan, a train and airplane manufacturing analyst for Société Générale, wasn’t sure the economics made sense, reports the Huffington Post.

“Ignoring the physics of it, to make it viable, pricing would have to be astronomical to have a reasonable payback period.”

In an interview with PBS, Marcel Jufer, a professor emeritus at École Polytechnique Fédérale de Lausanne in Switzerland, expressed doubts over Hyperloop’s vacuum pump system, which could cause a problem when loading passengers.

“You need to have some kind of airlock system at the extremity or in the stations for passengers. Doing this, you introduce a relatively important amount of air. Not a large amount, but it’s at atmospheric pressure, which means if you introduce 1 cubic meter of air at atmospheric pressure, it means it’s equivalent to 1,000 cubic meters of air at low pressure. It’s a relatively important disturbance.”

And even Bill Nye the Science Guy weighed in, tweeting:

#Hyperloop transport. Technology tough, but doable. Problems are: buying the rights-of-way & perception of Big Gov’t. Someday…

-; Bill Nye (@TheScienceGuy) August 12, 2013