One billionaire is betting big on another billionaire's dream project.
"After visiting Hyperloop One's test site in Nevada and meeting its leadership team this past summer, I am convinced this groundbreaking technology will change transportation as we know it and dramatically cut journey times", Branson said.
"With Virgin Hyperloop One, passengers and cargo will be loaded into a pod, and accelerate gradually via electric propulsion through a low-pressure tube".
In 2013, Musk pitched an idea for entrepreneurs to create a massive vacuum tube that could one day transport someone from Los Angeles to NY in 45 minutes.
"Virgin has been known for investing in and creating innovative companies over the years, and I look forward to making history together as we bring Hyperloop to the world as Virgin Hyperloop One".
Multiple startups took up the challenge, including Hyperloop One, cofounded by Musk's friend Shervin Pishevar. Hyperloop has already raised more than $150 million in debt and equity.
The entire field was shaken by the announcement in July that Elon Musk meant to build his own Hyperloop after all.
Several companies are now exploring the market, including Northeast Maglev, Hyperloop One and Hyperloop Transportation Technologies. In August this year Hyperloop One successfully managed to fire a pod at 192mph. Musk tweeted that he had "verbal government approvals" to build an underground tunnel from NY to Washington DC through his start-up The Boring Company, although he did not, in fact, have formal approval from any relevant government body.