Nasa is believed to have been quietly testing a revolutionary new method of space travel that could one day allow humans to travel at speeds faster than light.

Researchers say the new 'impossible' drive could carry passengers and their equipment to the moon in as little as four hours.

A trip to Alpha Centauri, which would take tens of thousands of years now, could be reached in just 100 years.

The system is based on electromagnetic drive, or EMDrive, which converts electrical energy into thrust without the need for rocket fuel.

The concept of an EmDrive engine is relatively simple. It provides thrust to a spacecraft by bouncing microwaves around in a closed container. Pictured is the first device created by Roger Sawyer

HOW DOES AN EMDRIVE WORK? The concept of an EmDrive engine is relatively simple. It provides thrust to a spacecraft by bouncing microwaves around in a closed container. Solar energy provides the electricity to power the microwaves, which means that no propellant is needed. Researchers previously believed this wouldn't work in the vacuum of space, but Nasa has allegedly shown otherwise. The implications for this could be huge. For instance, current satellites could be half the size they are today without the need to carry fuel. Humans could also travel further into space, generating their own propulsion on the way. Advertisement

According to classical physics, this should be impossible because it violates the law of conservation of momentum.

The law states that the momentum of a system is constant if there are no external forces acting on the system – which is why propellant is required in traditional rockets.

Researchers from the US, UK and China have demonstrated EMDrive over the past few decades, but their results have been controversial as no one has been exactly sure how it works.

Now, Nasa has built an EMDrive that works in conditions like those in space, according to users on forum NasaSpaceFlight.com.

A number of those discussing the plan on the technical forum claim to be Nasa engineers who are involved in the project.

The concept of an EmDrive engine is relatively simple. It provides thrust to a spacecraft by bouncing microwaves around in a closed container.

Solar energy provides the electricity to power the microwaves, which means that no propellant is needed.

The implications for this could be huge. For instance, current satellites could be half the size they are today without the need to carry fuel.

Humans could also travel further into space, generating their own propulsion on the way.

When London-based Roger Sawyer came up with concept in 2000, the only team that took him seriously was a group of Chinese scientists.

In 2009, the team allegedly produced 720 millinewton (or 72g) of thrust, enough to build a satellite thruster. But still, nobody believed they had achieved this.

Last year, Pennsylvania-based scientist Guido Fetta and his team at Nasa Eagleworks published a paper that demonstrates that a similar engine works on the same principles.

Their model, dubbed Cannae Drive, produces much less thrust at 30 to 50 micronewtons - less than a thousandth of the output of some relatively low-powered ion thrusters used today.

On the NasaSpaceFlight.com, those allegedly involved in the project claim that the reason previous EmDrive models were criticised were that none of the tests had been carried out in a vacuum.

Solar energy provides the electricity to power the microwaves, which means that no propellant is needed.The implications for this could be huge. For instance, current satellites could be half the size they are today without the need to carry fuel

Physics says particles in the quantum vacuum cannot be ionised, so therefore you cannot push against it. But Nasa's latest test is claimed to have shown otherwise.

'Nasa has successfully tested their EmDrive in a hard vacuum – the first time any organisation has reported such a successful test,' the researchers wrote.

'To this end, Nasa Eagleworks has now nullified the prevailing hypothesis that thrust measurements were due to thermal convection.'

However, Nasa's official site says that: 'There are many 'absurd' theories that have become reality over the years of scientific research.

'But for the near future, warp drive remains a dream,' in a post updated last month.