Alcubierre drive

Rather than exceeding the speed of light within a local reference frame, a spacecraft would traverse distances by contracting space in front of it and expanding space behind it, resulting in effective faster-than-light travel. Objects cannot accelerate to the speed of light within normal spacetime; instead, the Alcubierre drive shifts space around an object so that the object would arrive at its destination faster than light would in normal space.^[1]

Although the metric proposed by Alcubierre is mathematically valid (in that the proposal is consistent with the Einstein field equations), it may not be physically meaningful, in which case a drive will not be possible. Even if it is physically meaningful, its mere existence does not necessarily mean that a drive can be constructed. The proposed mechanism of the Alcubierre drive implies a negative energy density and therefore requires exotic matter. So if exotic matter with the correct properties does not exist then the drive could not be constructed. However, at the close of his original paper^[2] Alcubierre argued (following an argument developed by physicists analyzing traversable wormholes^[3][4]) that the Casimir vacuum between parallel plates could fulfill the negative-energy requirement for the Alcubierre drive.

Another possible issue is that, although the Alcubierre metric is consistent with Einstein's equations, general relativity does not incorporate quantum mechanics. Some physicists have presented arguments to suggest that a theory of quantum gravity (which would incorporate both theories) would eliminate those solutions in general relativity that allow for backwards time travel (see the chronology protection conjecture) and thus make the Alcubierre drive invalid.

Time to start packing up... 452b here we come.

NASA scientists take first steps to building faster-than-light warp engine that could make Star Trek a reality

Researchers at the NASA's Johnson Space Center are convinced they can turn science fiction to fact and prove warp speed might someday be possible.

To do this, they would need to break, or at least bend the rules of time and space famously laid out by Albert Einstein over 50-years ago.

Undeterred, Dr. Harold G. White and his team have begun small-scale experiments using infinitesimally small photons that could have galactic sized ramifications for the future of space travel for mankind.

Reality: Could warp speed - made popular in culture by Star Trek - one day become a reality

Dr. White, 43, is trying to manipulate or 'warp' the trajectory of a photon - put simply, he wants to see whether he can fold time and space around the photon to allow it to travel a greater distance, but at the same speed.

'Space has been expanding since the Big Bang 13.7 billion years ago,' said Dr. White to the New York Times.

And we know that when you look at some of the cosmology models, there were early periods of the universe where there was explosive inflation, where two point would've went receding away from each other at very rapid speeds.

'Nature can do it. So the question is, can we do it?'

Theoretical Warp Speed: This graph illustrates who Dr. Alcubierre postulates mankind could one create warp speeds in space

Despite the speed of light being seen as an absolute, Dr. White has been inspired by Mexican physicist, Miguel Alcubierre, who postulated a theory that allowed for faster-than-light but without contradicting Einstein

His theory was published in 1994 and involved enormous amounts of energy being used to expand and contract space itself - thereby generating a 'warp bubble' in which a spacecraft would travel.

Allowing space and time to act as the propellant by pulling the craft through the bubble, Dr. White explained it to the New York Times as stepping onto a moving walkway at an airport.

Despite Dr. Alcubierre stating his theory was simply conjecture, Dr. White thinks he and his team are edging towards making the realm of warp speed attainable.

However, Dr. White admits that his research is still small-scale and is light years away from any type of engine that could be constructed into a space ship like the USS Enterprise.

Galactic Speed Limit: Professor Albert Einstein as he attended a session of the Eighth American Scientific Congress in 1940

NASA is cautiously supportive of Dr. White's research with Steve Sich, the deputy director of engineering at the Johnson Space Center daying, 'You always have to be looking towards the future.'

Holding up his iPhone, Sich said, 'Forty years ago, this was Star Trek, Captain Kirk talking on a communicator whenever he wanted to. But today it exists because people made the battery technology that allows his device to exist, worked on the software technology, worked on the computational, the touch screen.'

Developing any form of warp drive would allow mankind to cut travel times to other star systems from tens of thousands of years to months.

Indeed, Richard Obousy, a supporter of the work of Dr. White says that more money should be put into developing the technology behind warp drives.

Dr. Miguel Alcubierre's theories on warped wormholes in space have inspired NASA's researchers at the Johnson Space Center

The Johnson Space Center in Houston, Texas is where Dr. White and his experimental research is taking shape

'We tend to overestimate what we can do on short time scales, but I think we massively underestimate what we can do on longer time scales,' said Obousy, who is president of Icarus Interstellar, a group working on a faster than light design.

Hoping to stop anyone getting carried away, Dr. Alcubierre pointed out a massive structural problem with any warp drive.

'At speeds larger than the speed of light, the front of the warp bubble cannot be reached by any signal from within the ship,' he said.

'This does not just mean we can’t turn it off; it is much worse. It means we can’t even turn it on in the first place.'

Kepler-452b: What It Would Be Like to Live On Earth's 'Cousin'

Kepler-452b may be Earth's close cousin, but living on the newfound world would still be an alien experience.

A group of pioneers magically transported to the surface of Kepler-452b — which is the closest thing to an "Earth twin" yet discovered, researchers announced yesterday (July 23) — would instantly realize they weren't on their home planet anymore. (And magic, or some sort of warp drive, must be invoked for such a journey, since Kepler-452b lies 1,400 light-years away.)

Kepler-452 is 60 percent wider than Earth and probably about five times more massive, so its surface gravity is considerably stronger than the pull people are used to here. Any hypothetical explorers would thus feel about twice as heavy on the alien world as they do on Earth, researchers said. [Exoplanet Kepler 452b: Closest Earth Twin in Pictures]

"It might be quite challenging at first," Jon Jenkins, of NASA's Ames Research Center in Moffett Field, California, said during a news conference yesterday. Jenkins is data analysis lead for the space agency's Kepler spacecraft, which discovered Kepler-452b.

But visitors to the exoplanet would probably be able to meet that challenge, said former astronaut John Grunsfeld, associate administrator of NASA's Science Mission Directorate. After all, he said, firefighters and backpackers routinely carry heavy loads, mimicking (albeit temporarily) the effect of increased surface gravity.

"If we were there, we'd get stronger," Grunsfeld said. "Our bones would actually get stronger. It would be like a workout every day."

The high-gravity environment would probably lead to significant changes in the bodies of Kepler-452b colonists over longer time spans, he and Jenkins said.

"I suspect that, over time, we would adapt to the conditions, and perhaps become stockier over a long period of many generations," Jenkins said.

Other features of life on Kepler-452b would be more familiar. For example, the exoplanet orbits a solar-type star at about the same distance at which Earth circles the sun. [Living on Other Planets: What Would It Be Like?]

"It would feel a lot like home, from the standpoint of the sunshine that you would experience," Jenkins said. Earth plants "would photosynthesize, just perfectly fine," he added.

Imagining other aspects of life on Kepler-452b requires much more speculation, since it's too far away to get a good look at. Researchers suspect that the planet is rocky, like Earth, but they don't know for sure. Kepler-452b probably has a thick atmosphere, liquid water and active volcanoes, but these are best guesses based on modeling work. 

Models also suggest that Kepler-452b might soon experience a runaway greenhouse effect, similar to the one that changed Venus from a potentially habitable world billions of years ago to the sweltering hothouse it is today, researchers said.

Kepler-452b's star is apparently older than the sun — 6 billion years, compared to 4.5 billion years. It's thus in a more energetic phase of its life cycle than the sun is; indeed, the star is about 10 percent larger and 20 percent brighter than Earth's sun. (That means the sunlight on Kepler-452b, while familiar to explorers from Earth, would not be exactly equivalent.)

The increased energy output of its sun might currently be causing Kepler-452b to heat up and lose its oceans — if the planet does indeed harbor oceans — to evaporation, subsequent breakup by ultraviolet light and atmospheric escape.

Such a scenario likely won't occur on Kepler-452b for another 500 million years or so, assuming estimates for the planet's size and the star's age are accurate, Jenkins said. (The stronger gravity of larger planets allows them to hang on to their surface water for longer periods of time in such situations than smaller worlds can.)

"But, you know, we don't know exactly," Jenkins said.

So he and other members of the discovery team helped devise an artist's concept that imagines how Kepler-452b would look if a runaway greenhouse effect were beginning to unfold.

The illustration shows "not oceans, but residual bodies of water that are highly concentrated in minerals after the oceans are largely gone, and you have lakes and pools and rivers left," Jenkins said. 

"It's a fascinating thing to think about, and I think it gives us an opportunity to take a pause and reflect on our own environment that we find ourselves in," he added. "We've been lucky and fortunate to live in a habitable zone for the last several billion years, and we'd like that to continue on."

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