TO INFINITY! AND BEYOND!!

OMGIMSOEXCITEDHAVEYOUHEARDABOUTTHENEWREACTIONLESSDRIVENASATESTEDWECANTOTALLYGOTOSPACEIWANTMYOWNSPACESHIPCOMMANDTHISISTHEBESTMOSTEXCITINGTHINGEVERIWILLQUITMYJOBTOGODEDICATEMYLIFETOTHISRIGHTNOW!!!!!

Deep breaths!  Deep breaths!  I'm going to hyperventilate if I don't calm down!  Give me just a second!

     Okay!  Let's take it from the top.  NASA has recently published a paper detailing their recent experiments conducted with what is currently being called the Cannae drive (Hi Scotty!) or QDrive.  Here's the theory: a weirdly shaped chamber has microwaves bounced around in it.  Because of the way the chamber is shaped, the microwaves bounce around in such a way as to generate thrust (measured in micro newtons, i.e. a very small amount).  Should the device work as described, it would mean a reaction-less drive had been achieved.  NASA tested the thing under some extremely strenuous conditions (although as has been pointed out by others, not identical conditions to space), and to the surprise of many, the damn thing actually worked!  So how and why is this a big deal, and what actually happened?  Let's take a look!

     First, a reaction-less drive is a type of engine that would generate thrust without any need for an outside force or net momentum exchange to produce linear motion.  In plain english, you move without pushing off of something else.  That doesn't sound that complicated but literally every form of movement we use currently does this.  Note I didn't say every form of engine, I said every form of movement.  Walking, we push against the ground to move forward, swimming we push against the water, planes push against the air, boats push against either the water or air (propeller engine or sailboat), cars also push against the ground, and rockets (once they're in space) push against their own fuel.  More accurately, they move by releasing matter (usually a gas because it can be compressed so maximizes how much you get for the space it takes up) in one direction pushing the ship in the other.  Space makes this a bit more complicated because there's nothing around the vessel to slow it down once it gets moving, so every time it wants to change course, it takes fuel to start moving and the same amount again to stop moving.
     This really complicates space travel as it's currently done because a huge portion of the mass of our current rockets (something around 90%) is simply the fuel to get them into space.  To give you an easier to visualize mental picture, to get an 18 wheeler into orbit you'd need a Boeing 747 made entirely of rocket fuel.  If the goal is to get somewhere further than orbit, we have to build enough fuel into the part of the ship that survives getting out of the atmosphere to get the ship pointed at the destination, accelerate towards it, stop when it gets there, and if it's a manned ship, it would need additional fuel to point the ship back at Earth, accelerate back, and slow down prior to reentry.  The amount of fuel that can be carried is finite, and the issue of dimishing returns starts to come into play at some point since approximately 10lbs of feul to get off the ground has to be added for every pound of fuel that will be used in space.
     A reaction-less drive would solve a lot of problems for getting around past orbit.  Lets say the drive weighted as much as the aforementioned 18 wheeler.  That means that you only have to come up with the one rocket fuel 747 to get to the moon or to get to Proxima Centauri since you don't have to add additional fuel to go a farther distance.  The other advantage is the possibility of continuous thrust for the trip.  I'll get into what that means more specifically a little later though.  The big problem with a reaction-less drive is that it violates a few laws of physics based on our current understanding, which makes developing one a bit of a problem.

     "Well how could they have developed a working one if it violates the laws of physics?" you ask.  The short answer is, we don't know yet.  There is quite a lot of data that NASA released, and aside from some short speculation, there isn't a lot dedicated to trying to explain the why.  Although it's very important to point out that no serious scientists involved with the project are suggesting its actually reaction-less (they just aren't sure what it's reacting with and how), the important part at this stage isn't actually why it works.  By everything they have observed, it does work.
     The really interesting part of this is, however it's working, it doesn't work in the way that it's inventor thought it was going to.  There were two models tested.  One was the one the inventor designed that included some slots in the reflection chamber that were integral to generating the thrust he theorized would be created.  The other was the same design, minus the slots.  In the experiment that was conducted, both seemed to work equally well.  The scientists running the experiment just have theorized that something about the device is interacting with quantum vacuum virtual plasma (as I understand this part, basically particles that aren't quite real in the physical sense but nevertheless exist everywhere even in space), and is pushing against that to generate the measured thrust.

     "Even if it is somehow working, what's the big deal?  The thrust is in micro newtons!  Space shuttles weight tons!"  That's where the unique environment of space actually works in our favor.  Let's stay you give your car a push on a flat street to get it started rolling and after a few feet it comes to a stop, and may have gotten up to 1 mile an hour.  In space, that push that gets the ship up to 1 mile an hour will keep it going at 1 mile an hour without any further thrust until it hits something.  So while you would have to keep pushing that car on Earth just to maintain the speed, if you keep pushing it in space you add to the speed.  If each second you are pushing it increases the speed by 1 mile an hour, after 1 minute the ship is going 60 miles an hour.  After two weeks the ship is traveling at around 1.2 MILLION miles per hour.  You can see how even a small push, as long as you can keep it going indefinitely, can add up over time.  This is why a drive that can continuously produce thrust for a very long period without having to carry a large amount of fuel (even if it's only a small amount of thrust produced) is such a huge advancement in space travel.
     The other thing to consider about the push the Cannae drive is producing is that the drive tested was a small model built solely for the purposes of this test.  The hope is that by scaling up the device, you could also significantly increase the thrust produced.  This is also the part where understanding how it's doing what it's doing would be useful.  If you know how something works, you can figure out how to make it work better.

     Overall there are still a few hurdles to jump.  The device will probably require a lot more testing on Earth.  At some point, one will have to be shipped up to the ISS for testing in actual space.  After that, a Cannae drive would have to be built strong enough to actually push a ship.  All of this also assumes that the drive is actually working and the motion is not caused by some other unforeseen anomaly.  I am very hopeful, though.  We could all have been born at the narrow window in human history to see the birth of interplanetary space flight.

Now if we can just get FTL travel solved with a warp field and subspace transmissions I can finally get my own starship...