French national railway company SNCF has decided to back one of the American startups currently at work on the Hyperloop — a self-powering, high-speed transportation link that could see passengers zipping around low-pressure tubes in levitating, train-like "capsules."

The Hyperloop is the brainchild of billionaire entrepreneur Elon Musk, best known for giving the world Tesla cars, Paypal, and SpaceX, a company that specializes in launching rockets and spacecraft. Initial plans for the Hyperloop were released in 2013.

Musk's vision for rail transport involves state of the art trains traveling through low-pressure tubes. The project was first revealed in 2013, when Musk released a 57-page document outlining his vision.

Powered by the overhead solar panels lining the Hyperloop tubes, Musk's system would see passenger capsules hurtling through the low-pressure tubes at speeds of up to 800 miles per hour.

Passengers of the Hyperloop — described by Musk as a "cross between a Concorde, a rail gun, and an air-hockey table" — will be able to travel from Los Angeles to San Francisco in just 30 minutes. A commute from Paris to Marseille, which takes just over three hours on an SNCF high-speed train, would shrink to 40 minutes.

And while Musk has claimed that a Hyperloop fare from LA to San Francisco will set you back a mere $20, the cost of making the link operational is expected to reach $6 billion.

Despite widespread skepticism around the viability of the Hyperloop, the SNCF seems to think the train of the future is more than just a low-pressure pipe dream.

According to AFP, it is not known how much money the SNCF has invested in the venture. When contacted by VICE News this morning, the rail company declined to comment on its recent investment.

The SNCF's contribution is part of the $80 million investment secured by LA tech startup Hyperloop One during its second round of financing.

Meanwhile, Hyperloop One undertook the first test of its system today in the desert outside of Las Vegas. It is not yet known how long the test will last, or how far the prototype will travel.

In 2015, the company announced that it would soon carry out tests on a one-kilometer track, experimenting with speeds of up to 540 kilometers per hour (335 miles per hour). According to AFP, the company predicted it would then build a full-scale prototype, capable of traveling up to 1,120 kilometers per hour (700 miles per hour) through a three-kilometer (1.9 mile) tube.

As part of its efforts to bring near-supersonic ground travel to the general public, Hyperloop One has also launched a feasibility study of routes in Finland and Sweden. It's also looking into building a high-speed freight link in Switzerland.

In November 2015, SNCF President Guillaume Pepy met Hyperloop One's co-founder Brogan Bambrogan at a summit organized by the magazine Challenges.

"We must still improve the [rail] system," Pepy said at the time. "Just as there will be cars with no drivers, new technologies allow us to imagine trains without conductors." Pepy also said that future rail links between Paris and Roissy airport "should be conceived in this way."

According to Challenges, the SNCF is working hard to keep up with the changing face of ground transport, and cannot afford not to invest in new rail technology.

The group is also developing another high-speed train project as part of a partnership with rail transport company Alstom and the French Agency for the Environment and Energy Management (ADEME). The French government has described the proposed train — which will be faster and more cost-efficient — as "the future generation of high-speed trains."

Meanwhile, Hyperloop One co-founder Shervin Pishevar — who is also Chairman of the group's board of directors — has said his own company's futuristic train project is "at the avant-garde of a movement to tackle one of the most burning issues facing the planet."

"The brightest minds are coming together at the right time to eliminate the distances and borders that separate economies and cultures," said Pishevar.

But not everyone is convinced this technology is just around the corner. Yves Crozet is a professor at Lyon University and a member of the Transport, Urban Planning, and Economics Laboratory — a research institute based in Lyon. Crozet said the SNCF had made a risky investment by pouring money into Hyperloop. The project, he said, was at best an attempt by Musk to "stall" the SNCF's own plans to develop a high-speed rail link in California.

Crozet compared the Hyperloop to the famous "Aérotrain" — a hovertrain developed by engineer Jean Bertin in the 60s. Plans to build the train were later dropped in favor of France's high-speed TGV train.

Eric Vidalenc, an economist and an energy expert, shares Crozet's skepticism. Nothing in Musk's 2013 document guarantees the Hyperloop's energy efficiency.

"Hyperloop functions with solar panels, but it will have to circulate at night," the expert noted. "There's no explanation [in Musk's document] of what happens then."

Vidalenc thinks predictions that the train could be up and running in four years are highly exaggerated. Hyperloop Transportation Technologies — the other startup developing Hyperloop technology — has implied the system could be operational by 2020.

And even if the train does get built, Vidalenc is not sure how useful it will be. A train traveling at near-supersonic speeds, he argues, will only be able to make very limited stops, and will therefore only serve to link major cities. "It could solve some problems, such as how to get from Paris to Marseille faster. But for other regions, the problems would remain the same, or get worse," he said.

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