The new episode in the Star Wars franchise was released last week to much fanfare. I was there and loved every minute of it. Thus far, the film has broken records and made millions around the globel. It is dominating the theaters and will continue to do so for a while.
As I watched the new addition to the Star Wars universe, I found one thing to be so awesome that I could not help but want to write something about it. Therefore, I want to discuss the physics behind the Starkiller base. I will state upfront that I will do my best to not put out any plot spoilers. I will just discuss that the base exists in the movie and physics that makes it a challenge. I will not discuss plot lines or anything else. If I do spoil anything, then you have my sincerest apologizes, but this thing is awesome!
Anyway, besides breaking records in ticket sales and merchandising (no surprise for Disney), Star Wars: The Force Awakens has appeared to have also broken the laws of physics. The Starkiller base is an ice planet that has been converted into "the ultimate power in the universe" by the First Order. Overall, it can be considered to be the Death Star on steroids in both size and power. As with the Death Star, the base has the ability to destroy planets with immense jets of plasma that are shot from the core of the planet. The question becomes where does this plasma power come from? The answer is quite simple; the planet steals the power and plasma from a near by star. This action of eating a star essentially "charges up" the superweapon, which means the doom for any planet that is in the First Order's way.
Now, a star is a hydrodynamic ball of heated plasma (charged gases) that has incredible size, mass, and heat. Therefore, when the Starkiller base absorbs one it must have to adjust for the immense heat and gravity that is being stored. Now, in the movie they refer to the absorbed star as the Sun (kind of strange). Therefore, I will compare it to our local star and the ice planet to the Earth.
In order to get the star, the first thing that needs to be done is that you have to compress the star to fit in whatever is being used to contain it. Assuming that this is a container the size of the planet's core, you have to take a ball of hot gas about 7x10^8 m in radius and shrink it to about 3.5 x 10^6 m (about the size of Earth's core). This would be quite the engineering feat. It is not exactly the size of the Schwarzschild radius for the Sun, which is the limit where the sun becomes a black hole, but it is still small. Since the mass of the Sun is about 2.0 x 10^30 kg and given the Schwarzschild radius is
R_sch = 2GM / c^2,
where G is Newton's gravitational constant, M is the mass of the Sun, and c is the speed of light, the Sun can be compressed into a ball about 3000 m in radius before becoming a black hole. Therefore, while it is not a black hole, it would still make for a pretty dense star.
Okay, so this may be an issue. However, a larger problem is that the mass of the Sun would increase the acceleration due to gravity by a factor of about 300000. Earth's acceleration is 9.8 m/s^2, while the Sun's gravitational acceleration is about 300 m/s^2 at its surface. Therefore, at the surface of the Earth-sized planet, the added mass would increase the gravitational acceleration to 3.2 x 10^6 m/s^2, which will turn you into mush! This is a good approximation, since the Starkiller base is on an Earth-like planet that seems to be a bit smaller than Earth itself.
Therefore, it is not that feasible that they are just containing a star in the core of the planet. To do this, they would need a confinement field to keep the star contained and an antigravity generator to keep the surface gravity at a comfortable level. Being that the amount of energy needed for containment would probably be close to the amount energy emitted from the star itself, it is unlikely that it will work. If you disagree, then built your own Starkiller base and prove me wrong. Furthermore, since they are in the same universe and just in a galaxy a long time ago and far far away, the law of physics should be equivalent, and given that there is no experimental or theoretical evidence of antigravity, the second factor is a sticking point as well.
How about converting the mass of the star into pure energy? Well, that would make the situation really hot. They did use an ice planet, but there are trees on it so it is not exactly Hoth. So, how much heat are we talking about? Considering the Sun's surface temperature is about 6000 K and it has a core temperature over 15 million K with its power output at around 3.86 x 10^26 Watts (Joules per second), it is going to make for some serious global warming! Overall, whatever is containing the star will have to withstand some pretty high temperatures. Since steel melts at 1800 K, whatever the base is constructed from must be some superalloy and, no, adamantium won't work either. It melts at 4400 K. Although, there are new materials being discovered all the time. The highest melting point thus far is a material made from hafnium, nitrogen and carbon that has a melting point of over 7000 K.
Well, we also have not included the energy from converting the mass of star into pure energy. The energy added from the mass itself adds another 2 x 10^47 J of energy. Assuming a strict E = mc^2 conversion. If you compare that to the largest tested hydrogen bomb (2 x 10^17 J), it is highly unlikely the planet and any containment field could hold that.
Overall, the Starkiller base definitely has the power to destroy planets and whole solar systems. However, scientifically, it would be hard to contain. Therefore, if you lose containment on the base, then you the base and planet would be consumed by the star! This is why I love science fiction and Star Wars. The ideas that are put forth may be out of this universe, but it makes for some very good story telling.