Monday, December 25, 2017

The physics (or lack there of) of Star Wars: The Last Jedi (Hyperspace Kamikaze)

Let me first say, that I LOVED The Last Jedi. I think it is great. If you don't, then fine. But this is not the time or place to discuss whether the movie was good or not (though I probably have more posts coming on that). Now is the time how to, once more, explain how the latest movie RUINED ALL OF STAR WARS...

Needless to say, but... spoilers ahead!

A few Disclaimers
1- Let me reiterate, spoilers for the movie lie ahead, so if you haven't seen it, stop reading and come back after you do (go ahead and join us/follow us on facebook or twitter!)
2- The movie is AMAZING. Anytime here that I say that "Star Wars is ruined" I don't mean it literally.
3- I am not guaranteeing full accuracy of this. I do this just because I am really nerdy and think about these things... A lot of approximation and some rounding goes into this sort of math. I am not doing SCIENCE. I am writing a blog post. But I do try and make sure there is some "weight" to the numbers I do throw around.
4- And before you go "This guy doesn't know anything," or "I know physics better", I'll just say I have an MS in Applied Physics, so I have a decent grasp of this kind of stuff.

If you recall two years ago, I did a similar piece after the Force Awakens.

Let me say first you should probably read that, especially the part on the "Solo Maneuver". But in case you don't want to spend the time doing that I will sum it up here

1- Going Lightspeed through shields makes them useless
2- Even if "Hypserspace" allows you to not interact with matter, there has to be a transition speed between 0 and c (lightspeed).
3- Why slow back down? Why not just stay at .99c and run into things. Gives you LIGHT SPEED MISSILES.

So, I guess I predicted that didn't I... because that's EXACTLY what happened in Episode 8.

Vice Admiral Holdo takes her flagship, the Raddus (named after Admiral Raddus from Rogue One) and RAMS IT RIGHT INTO THE FIRST ORDER FLEET.
This. In space.
So four things to take away from this scene
1- This is the ONLY moment in Star Wars with NO SOUND. Everyone knows there is sound in Star Wars space! But seriously, its funny how this moment, despite every other flaw, actually does follow one real scientific truth. "In space, no one can hear you lightspeed kamikaze"

2- Why aren't lightspeed droid missiles a thing. SERIOUSLY. Even if they aren't that small. A-Wing sized I guess. That is big enough for a hyperdrive AND would be pretty devastating. Good enough to kill a Superstar Destroyer, good enough for me. Lets put it at  conservative 10 tons. That's as much as an F-16 fighter jet about, so seems good. So 9,200 kg ish.
Now I could go into alot more ballistics and impact physics. It's actually what I got my master's degree in. However, for simplicity here we are just going to go with the super simple equation for kinetic energy.
Next we establish what c is. Rounded up its about 300,000 km/s.

So going .99c puts us at 297,000 km/s.

Now do the math and we get 4.06 x 10^20 JOULES. Or 406 EXAJOULES. That's a lot of energy in that A-wing sized droid controlled missile.

So step that up to the Raddus. Extrapolating from some of the largest warships in the world, Nimitz Class aircraft carriers (100k tons-ish), I would put the 3500m long, 460m tall, 700m wide Raddus at about 1.5 x 10^11 kg. That's a lot of mass.

Rough math for its kinetic energy in the same situation, 6.6*10^27 joules. Or 6.6*10^15 terajoules. Or finally something manageable... 6,600 yottajoules. yodajoules? (1 yottajoule is 1 SEPTILLION joules).
The death star, well that operated at 225,000,000 yottajoules. So the Raddus ramming manuever is only 1/34,090th as powerful as the Death Star.

But that is still 17.36 TIMES MORE ENERGY THAN THE SUN PUTS OUT IN A SECOND. And we were AIMING IT AT A SHIP. For all its mass, the Supremacy is about one trillionth the mass of Alderann. So if Alderran was instantly obliterated by a weapon only 34,000 times more powerful, I think 1 trillionth the mass is no issue for instant obliteration of a weapon 1/34,090th the Death Star.

But even if it DID hit a planet, it would be a cataclsymic event.

To put this into perspective, a 1 megaton nuclear blast would be 418 Terajoules, making a 1 kiloton blast 4.18 terajoules. This would make the blast at Hiroshima about 63 Terajoules.

The A-wing hyperspace missile droid collision would be 6.4*10^6 times more powerful than Hiroshima. The Raddus is at 1.05*10^14 times more powerful than Hiroshima. A Turbolaser is suppossedly 200 gigatons around the time of the clone wars, so that makes it 8.36*10^19 joules, or 1.3*10^6 times more powerful than Hiroshima.

Directly comparing the two, the A-wing is 5 times more powerful than a Turbolaser and the Raddus is 7.9*10^7 times more powerful than a Turbolaser. And shields stop Turbolasers.

But for even more perspective, the Asteroid that killed the dinosaurs was only 1x10^9 times more powerful than Hiroshima. That's right, an the Raddus running into Earth at 0.99c would be equivalent of 105,000 Dinosaur killing asteroids...
Really makes you wonder if the Death Star was necessary after all... (hint, it wasn't).

Now in both these cases, the A-Wing and the Raddus, imagine that much force being transferred in an infinitesimal moment. That's ALOT OF FORCE. Makes the lightside and the darkside insignificant in comparison.

It wouldn't just cut the ships in two. It would OBLITERATE THEM. Nothing would have survived on the supremacy. Sure there are other articles out there saying they aren't sure it would go down the way it did in the film. I am hear to tell you that it MOST CERTAINTY WOULD NOT. And not for the same reason as that other article. They have no clue about hypervelocity impacts. Because the real killer here is the shockwave propagation through the Supremacy. And with that big of an impact at those speeds, it would be tremendous. Nothing would have been left of either ship.

Though nothing would have happened to the surrounding star destroyers UNLESS spall shot off at near light speed into them.

Basically, Hyperspace Missiles are the single greatest weapon that can exist in Star Wars.

To reiterate from my last Star Wars phsyics post, they have the added benefit of
-You can strike from ANYWHERE IN THE GALAXY
-Your enemy cannot detect you
-You are moving too fast for anything to stop you even if it could
-There are no (known) defenses for this. Han proved shields don't work, so what else is there?

3- Objects in Hyperspace must not interact with mass, and only energy some how?

So its established in Episode 7 that to get through the shield (an energy field) Han has to be in hyperspace. And we know that gravitational fields can rip ships out of hyperspace or prevent them from jumping into it from back ground lore and the cartoons (Interdictor cruisers people).

And Holdo looks like she is only ACCELERATING to Hyperspace in The Last Jedi, and not yet at it (thus why I did everything above at 0.99c and not 1.0+).
Bust most importantly, even if my math above is just rough approximations and doesn't fully encapsulate the complexities of light speed collisions, I think it does well enough at demonstrating the energy involved is ENORMOUS.

So even if not specifically used militarily, why is this not used by Terrorists? Or more to the point... why does it never happen accidentally.

All it would take is a miscalculation or a computer error and BAM, Coruscant is gone as some lowly junk goods trader plows into the planet for coming out of hyperspace 2 seconds too late. But that never happens right? You never hear of the planets that are vaporized by accident.

To expect all calculations across the galaxy are always perfect to avoid such accidents is just too much to assume. It would require ultra precise numbers, and incredibly precise locations... in a Galaxy KNOWN to have uncharted star systems. Beyond that, it would require the impossibility of a perfect, synchronized time reference point. But we are talking about FTL and interstellar distances soooooo that can't happen. Relativity says that the clocks will never match.

Also, those computers would have to be BEASTLY. And based on what you SEE in Star Wars... they don't have computers that powerful. I mean, they have to access the Death Star plans on Scariff in Rogue One with an Analog System. The schematics for the Death Star have all the resolution of late 1970s computer graphics (lol).

So if these accidents COULD happen, they WOULD have happened, and you would see A LOT more precaution in regards to Space Flight, particularly around Coruscant in the prequels. The fact that you don't means it can't be a concern. Meaning that once at Hyperspeed, objects cease to interact with each other physically.

Its like it must be a parallel reality or something they travel through, where you can go faster than the speed of light and yet not have relativistic repercussions, maintaining a bubble of reality around your own vessel in order to return to the proper time, covering vast interstellar gulfs of space in a fraction of time it would actually take even at the speed of light...

Sound familiar?

Last take away from that scene
4- The tacticians and military scientists of the Star Wars universe are idiots for not realizing any of this.