Before we get started let me just put this here:
LARGE PLOT SPOILERS BELOW FOR THE NEW STAR WARS MOVIE
There, now that’s out of the way let’s get onto the meat of this post.
I, like all Star Wars fans, had been very much looking forward to the latest movie. Whilst I have my reservations about some aspects of it (which I’ll reserve for a conversation over a couple beers as to avoid a flamewar on here) I still thoroughly enjoyed it. However like most sci-fi movies The Force Awakens plays fast and loose with science. Following the rules of our universe when it suits the plot and sweeping them under the rug when it doesn’t. There are some grievances that I’m willing to let slide in this respect, this is fiction after all, however there’s at least one egregarious scene in which physics is completely thrown out the window when it really didn’t need to be.
My grievance lies with Starkiller base, the bigger and badder version of the Death Star which now encompasses an entire planet rather than just a small artificial moon. Whether such a device is something that could be built is something I’m willing to gloss over however the fact that it’s powered by drawing off mass from its neighbouring star brings with it a few niggling questions. It’s ultimate destruction, which then brings about the resurrection of its parent star, is also not something that would happen and not something I’d be willing to write off with space magic.
We get to see Starkiller base fire once and then begin preparations for firing again. Assuming that it didn’t travel to a new star in the interim (I don’t remember that being indicated as such) then it would’ve consumed half of its parent star’s mass to fire that single shot. That would’ve caused all sorts of grief for everything in orbit around it, not to mention the fact that that mass is now present on Starkiller base itself. Any asteroid or other debris near by should have rocketed down to the surface with incredible speed, laying waste to the surface. I’m willing to give a pass for a “gravity pump” or something else on the inside parts but being able to negate half the mass of a star over the entire planet is pure fantasy rather than a stretch of fiction.
However the final destruction of Starkiller base is the most egregious flaunt of the laws of physics. Putting aside all the mass contained within the star issue for a moment when it was all released the result would not be a new sun just like the old one. Whilst the mass was likely not compressed past its Schwarzschild radius (I’m assuming it’s a Sun like star) it would still be far too compressed to simply balloon back out. Instead it would likely become a white dwarf, that is if the explosion wasn’t violent enough to simply disperse the star’s material across its solar system. Since the system that Starkiller base resides in was never named I’m hazarding a guess it’s not relevant to the future plot so the returning sun just seems like a little bit of laziness more than anything else.
Of course I’m not advocating for 100% scientific accuracy in all films (indeed I don’t think there’s one good sci-fi epic that does) however a few nods here or there wouldn’t go astray. There are certain times where scientific accuracy would harm the plot and in that case I’m fine to relinquish it to induldge in the fantasy. Other times however it would do no harm and provide an interesting talking point as sometimes the physical reality can be far more interesting than the fantasy.