The Broken Physics of “The Umbrella Academy” Finale

Published 5 years, 3 weeks past

Not long ago, Kat and I got around to watching The Umbrella Academy’s first season on Netflix.  I thought it was pretty good!  It was a decent mix of good decisions and bad decisions by people in the story, I liked most of the characters and their portrayals, and I thought the narrative arcs came to good places. Not perfect, but good.

Except.  I have to talk about the finale, people.  I have to get into why the ending, the very last few minutes of season one, just didn’t work for me.  And in order to do that, I’m going to deploy, for the first time ever, a WordPress Spoiler Cut™ on this here blog o’ mine, because this post is spoilerrific.  Ready?  Here we go.

Okay.  So, Vanya bleaches out, bad plans are executed, the sound of a gunshot somehow nullifies Vanya instead of charging her even further, magic energy beam somehow hits the Moon.  And then, a little less than two minutes later, this.


Now hold on just a damn second.

You know all the coolio particle trails behind the BMF and tails behind the other impactors?  Yeah, no.  There’s no atmosphere in space to cause things to fall off and slow down.  Anything that “fell off” would fly in close formation with its parent body, slowly drifting further away but moving at the same velocity.  And they most certainly wouldn’t drop back and then speed up to match velocity with the parent body like some kind of magical space fairy dust.

But that arguably artistic problem aside, let’s talk about the problem of distance.  That ejected Moon fragment takes, according to the Netflix video player clock, just under 110 seconds to get from the Moon to the Earth.  That’s really, really fast.

How fast?  Well, let’s find the slowest possible case.  Assume Vanya accidentally zapped La Luna at its moment of perigee, which is 356,400 kilometers.  The ejected fragment doesn’t have to traverse that entire distance, though; it only has to reach the Earth’s surface.  (Perigee is a measurement between the centers of mass of the two bodies, not their surfaces.)  The Earth has an Equatorial radius of 6,378.1km.  And what the heck, even though it makes no physical sense, let’s be overly generous and subtract the Moon’s 1,738.1km equatorial radius.  This means the Big Moon Fragment (hereafter BMF) has to cover 348,283.8 kilometers.

Moving that far in 110 seconds means a speed of 3,166 kilometers per second (km/s).  That is just a hair over 1% the speed of light in a vacuum.  Even if we assume there was some editing lossage and its traversal time was a half-minute longer, at 140 seconds, we get 2,488km/s, which is about 0.83% c.

I don’t care how massive a fragment of the Moon got ejected, instantly accelerating it to ~0.01c is not going to leave you with one large chunk.  I’m not even sure it will leave you with solid matter, but I’m not inclined to do that math.  Maybe someone who’s good with matter and energy can leave a comment.

But again, remember, we’re talking about speeds in the vicinity of 3,000km/s.  Which leads us to the next set of problems: the observed movement of the BMF is nowhere close to that, and the visible effects aren’t consistent with its size or its movement.

In the impact scene, the Earth’s limb is notably curved.  That means the BMF is enormous.  I did a sizing comparison using a full-Earth image, and determined the BMF is approximately the size of Germany: 650km by 800km.  (In the cross-section we can see, that is.)  As it happens, the BMF takes about one second to move its own width across the screen, which means a speed of about 600km/s.

At that speed, it should have taken 580 seconds, or 9 minutes 40 seconds, to reach Earth.  Assuming it somehow stayed intact after being instantly accelerated to such speeds, that is.

(Yes, it’s true that the mutual gravitational attraction between Earth and the BMF would have sped it up a bit, but at these speeds, the difference would be negligible.  If you’re already traveling at 600km/s, another km/s or three isn’t going to move the needle all that much.  And anyway, that means it left the Moon slower than its impact velocity, granting even more time.)

But wait!  The BMF is closer to the camera’s viewpoint than the Earth’s limb, which means it’s probably smaller than first assumed.  Let’s say it’s about two-thirds the previously-claimed dimensions; that would make it about 430km by 550km.  That size reduces its speed to around 450km/s, which adds another three minutes to the trip, for a total of 12 minutes 54 seconds.  Cut it to half the initially measured size, and you get around 300km/s, or 19 minutes 20 seconds.

But wait again!  As the BMF comes in for landing, a plasma front develops in front of it as it pushes through the atmosphere.  Let’s assume, wildly generously, that this plasma front first forms right at the Kármán line, which is 100 kilometers above the Earth’s surface and is taken by some as the boundary between Earth and space.  Given that assumption, the BMF is reduced to about 100km × 150km, which means it’s moving at around 100km/s.

At which speed, the BMF would have taken 58 minutes to reach Earth.  With that kind of time, the Academy might’ve been able to avert the Apocalypse after all — wake Vanya, apologize profusely, and ask her very nicely to put the Moon back together, maybe.

Now, given the observed visual size both at ejection from the Moon and at Earthfall, there’s no way it could be as small as 100km across.  I could maybe see 250km, but 350–450km is much more likely. (Which is around the size of Ohio, as it happens.)

Even if we go with 100km across — who knows, maybe enormous pieces of it flew away somehow and left only a 100km core, sure, why not — the BMF is up to ten times bigger than the Chicxulub impactor that wiped out the dinosaurs.  Just that single BMF impact and all of the superheated ejecta that would rain down worldwide, never mind all the other smaller chunks shown slamming into the Earth, would dump so much energy into the atmosphere that Number Five should have jumped into a literal Inferno, not a rubble-strewn landscape filled with still-flaming gas mains, intact newspapers, and, you know, breathable air.

There is also the question of exactly how the BMF managed to so precisely target Earth.  Contrary to ego- and geocentric expectations, the Earth is not the center of the Universe, so things do not just fall towards it by default.  If you want to start at the Moon and head straight toward Earth, you have to cancel the Moon’s orbital velocity, which is just over one kilometer per second.

Since we’re talking about hundreds of kilometers per second of velocity for the BMF, we can simply assume the fragment was ejected at an angle just slightly behind a straight line to the Earth, perfectly cancelling out the Moon’s orbital velocity and putting the BMF on a precise impact trajectory.  The odds of its ejection angle being that precise are (ahem) astronomically small, but at this point, it’s the least impossible thing about the physics involved.

Oh, and did you know that seismic waves move through the Earth’s crust at around 5km/s, whereas airborne shock waves start out supersonic but quickly fall into the subsonic range, which is 0.33km/s?  What I’m saying is, long before the flamefront reached the Icarus theater, gargantuan earthquakes should have reduced every building to shards and pebbles.  But, I dunno, never mind that, I guess?

If you’ve made it this far, well, I salute you.  And you might be thinking, “Dude, it’s a superhero comic book show, just suspend your disbelief.” But the thing is, once the magic superhero stuff’s effects have ceased, the side effects of the superhero magic operate in the context of the regular physical world.  Unless the narrative established that this is a Universe where the Moon is ten times close to Earth than it is now — and imagine those ocean tides — we’re left with several irreconcilable observations.  They’d have done better to have Vanya just conjure a massive, fast-moving, Earth-targeted asteroid out of nothingness.

I’ll let Number Five’s expression sum it up for me.

The character of Number Five looking frustrated, disgusted, and a little annoyed.

Comments (11)

  1. Unfortunately, there’s a lot of this about, not just in made-for-TV science fiction, and not just by writers who don’t have technical backgrounds. It’s just that the people who ought to know better make mistakes that are fewer orders of magnitude adrift, so the reader has to do bit more calculation — or know the magnitude of the answer in advance — to spot the problem.

    That doesn’t stop it disrupting suspension of disbelief when you hit it, though — the final act of Stephen Baxter’s Ring relies on a factor of ten error in one important quantity in the set-up, and about a factor of around 1000 in another background factor, either of which alone would completely disconnect the protagonists from what they were attempting to achieve.

  2. That’s intense dude! I never really get too upset about physics in superhero movies, but I do get irate over economic plot holes. Maybe together we’d make a good super hero team ;)

  3. THIS. All of this.

    I want the superheros in my entertainment to be the only things violating the laws of physics. I’m happy to play along with the super powers but I want those characters to be interacting with the world I’m familiar with. I want to be able to judge how high or low the stakes are based on my experience of the world.

    How quickly they zap from Korea back to Wakanda in Infinity War makes me angry too, since we’re on the subject.

  4. Yes, yes, yes.

    Epic post Eric.

    I think flick this over to someone like Randel Munroe ( I loved his stories in what if?) and see if he can fine tune any of the bits you avoided deeper maths.

    I watched a movie the other day, Valarian, which said the space station had traveled 700 million miles since leaving Earth to make it sound like it’s really far, but turns out it is about as far as Saturn.

  5. If you’re ever looking for a superhero show / à la X-Force (the kind where the superheroes have to deal with real-world scenarios/fall-out) – you might like Misfits or The Boys. No meteors involved! Haha.

  6. I think getting the art right is untenable for really any special effects — you could pick apart most any CGI explosion in any movie at this level. So I’m personally not as concerned about the particle trails or other such things.

    On the mechanics, though, I’m with you entirely. Which is in fact how I found this page — I got done watching the show and went looking for somewhere to vent.

    I would point out, though, that, given the already absurd speeds we’re dealing with, I do not believe the fragment would miss the Earth if shot directly at it from the moon. To a good approximation, we can suppose that the fragment travels 1 km/s perpendicular to the line intersecting the earth and moon centers throughout the motion. In which case it misses the point on Earth where the moon is at the zenith by only 110 km.

    However, it will then hit the Earth (inelastically, based on the visuals) with a kinetic energy a few orders of magnitude above Earth’s binding energy. So, the Earth will do something somewhere between Humpty Dumpty and Alderaan. Great going, Vanya.

    Isn’t it funny though how it’s the things that are just not quite right that break our suspension of disbelief? We watched a show about people with superpowers and it’s the way the moon exploded that bugs us.

  7. THANK you! I enjoyed this series so much, I broke my own rule and binged the last 3 episodes; it was pretty satisfying – up until that complete and utter drivel at the last moments! Why does good TV keep doing this??!

  8. While I’m from a scientific background and agree with all your points I absolutely LOVED the over the top scenario with my one gripe being the time it took to reach the earth as you said, if you imagine the ‘blue marbel’ image of the earth from the moon it gives a perspective that makes the time travelled massively implausible. Great breakdown though enjoyed your maths

  9. I entirely agree.
    The tv show is over for me. I drop out of series and movies all the time, mostly because of medical science defects and improvisation, since it’s my field of work, and the gross mistakes of writers and producers are astonishing. Things a third rate doctor could help with, let alone a good one!
    I am not a physicist but this moon scene was instantly wrong for me.

  10. I’m surprised that nobody mentions an other problem with destroying the moon. Vanya’s superpower is controlling the sound waves… SOUND waves… in space…

  11. Thank you! I feel vindicated. I knew I couldn’t possibly be alone! When Five said it’ll be here in 60 seconds, I’m like, waaaaaaiiiiiit a hot second. I’ve had engineering schooling, but it shouldn’t take much more that high school physics to tell something is amiss with that. I love super heros and Sci-Fi, and I’m happy to suspend my disbelief regarding things that are totally made up. Fine, make whatever rules you want for something that doesnt exist… but don’t mess with physics! It’s the law! You caught quite a few inconsistencies with this one, good job!

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