system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Whats a warp field and how did NASA accidentally create one?

Also, why is it useful?
Thank you!
gpt
The idea of a warp field is a bit of theory that works out on paper but we haven't been able to try it experimentally—it requires negative mass.  The idea is core to the Alcubierre drive, which would allow for faster-than-light travel.

The principal is that while an object cannot move through space faster than the speed of light, space may be stretched and contracted according to the equations Einstein put forward with General Relativity.  This drive compresses and expands space to arrive at a destination sooner than would be possible at the speed of light on un-stretched space.

As for the recent report, it's *probably* just media spouting nonsense.  It's a result coming from the group that's investigating the Emdrive, which is another science-fiction-sounding spaceflight engine.  The neat thing about the Emdrive is that it claims to be able to produce thrust without fuel.  Normal rockets have to shoot fuel in one direction to travel the other, which causes us to have to use even bigger rockets to get them off the ground. This tends to result in *enormous* rockets if you want to go particularly far, and even still you can barely get out of the solar system.

The Emdrive was tested about a year ago at NASA's Johnson Space Center in Houston, as was a similar device, the Cannae drive.  These tests have been controversial as they would seem to demonstrate a violation of conservation of momentum, which is quite an extraordinary claim that is backed up with a lot of "I don't know"s and shrugged shoulders.  The researchers are pretty sure they've measured a force, but they can't nail down exactly where it's coming from.  They've tried to eliminate various mundane sources of the force, but they've also eliminated much of the original theoretical justification for why a legitimate force would exist in the first place (the Emdrive requires a tapered cavity, while the Cannae drive requires a cavity with slots.  A non-tapered, non-slotted cavity still produced the same measurement).

Thus, they're looking into things further to try to figure out what's actually going on.  In doing so they tried shooting a beam of light through the cavity to measure how long it takes to travel.  What they found was that the light traveled faster than expected—faster than the accepted speed of light.  This could be possible if an Alcubierre effect is occuring inside of the Emdrive, but there is no theoretical basis for why it would do so (once again, Alcubierre drives require negative mass).

I should point out that this is not the first time that faster than light travel has been experimentally measured.  Some time ago faster than light neutrinos were apparently observed, but later investigation showed it to be a calibration error.  It is too soon to fully accept the observation as true.  For now it's firmly in the realm of "probably just an experimental error but it would be really cool if it isn't and would rewrite a lot of physics."