In Star Trek, the Warp drive was the fictional technology that allowed for faster than light travel, for humans to go where no one has ever gone before (and for Kirk to duly ignore the Prime Directive).
But in the world outside Star Trek, Warp drives surely couldn’t exist… right?
Enter the Alcubierre drive, a speculative idea proposed by theoretical physicist Miguel Alcubierre in 1994, which exploits a loophole in Einstein’s Theory of Special Relativity which proves that nothing can move faster than the speed of light, by instead manipulating space-time, which we believe has no speed limit in its ability to expand and contract.
The Alcubierre drive would create a warp bubble (genuine term) around the object by using gravity to contract space time in front of it, and expand space time behind it. Effectively, we move the space around the object as opposed to moving the object. As the empty space behind the object expands it would “push” the craft forward.
To achieve this, the craft would effectively have to create negative energy, which arises from Heisenberg’s Uncertainty Principle (that we can’t precisely know the values of complementary variables, like position and momentum), where the energy of a field can randomly change, sometimes to less than zero.
Alcubierre drives can exploit phenomena like the Casimir Effect to do this. The Casimir effect follows an experiment where two uncharged metal plates placed parallel with one another, changed the amount of energy between them in such a way that the plates were attracted to each other. In effect, the plates reduce the energy in the gap between them; creating negative energy and pulling the plates together.
While it’s mathematically sound, the Alcubierre drive faces numerous difficulties. One of the main issues is the amount of energy that would be necessary to develop a warp drive. Some estimates have said the amount of energy necessary would be greater than the entire mass in the observable Universe. Small atoms would require the energy equivalent of three Suns to warp across the Milky Way.
It might be for this reason that the Alcubierre drive was largely ignored until 2012, when at the 100 Year Starship Symposium, NASA scientist Harold White claimed to have found a way to reduce the energy requirements to about the size of the Voyager 1 probe (which weighs about 700kg), by changing the geometry of the warp bubble.
By making the thickness of the negative energy ring into a larger, more doughnut-like shape, it can drastically reduce the energy necessary to warp. Some models have suggested that such a system could propel a ship at ten times the speed of light – fast enough to get to Alpha Centauri (the closest star system to us) in just six months.
But issues still remain. The design proposed by White would still require some 65 exajoules of energy, or about the amount the US uses every year.
Super high temperatures caused by Hawking Radiation in the warp bubble would likely cook everything inside it, and likely destroy the warp bubble itself. Another issue exists in the form of when the craft in the warp bubble comes out of warp, and any aliens we meet at the destination “would be gamma ray and high energy particle blasted into oblivion” (which is the best thing I’ve ever read in a peer reviewed paper).
However, that hasn’t stopped them from trying. At the Eagleworks Lab based at NASA’s Johnson Space Centre, a small team of scientists claimed to have successfully tested an electromagnetic propulsion drive. The idea behind the EM drive was that microwave radiation, reflected back and forth in cavities, could directly convert the electrical energy to thrust without the need to expel any propellant. It was met with strong criticism from the scientific community for violating Newton’s Third Law for conservation of momentum.
Explanations for the observed propulsion, such as thermal currents caused by the microwaves, have been ruled out, as the drive was tested in a hard vacuum (purportedly, the only evidence of this exists on an internet forum, not a peer reviewed paper), and it isn’t the first time Eagleworks has made these sorts of fictitious claims.
But with NASA’s stated goal to develop interstellar spacecraft by 2100, it shouldn’t be surprising that we’re still waiting for a working warp drive.
After all, it did take until 2063 for Zefram Cochrane to fly the first warp ship.