Review: “Edge of Tomorrow”

Plot:

In 2015, hostile aliens that humans call “Mimics” invade Germany and conquer most of Europe within five years. Human populations and military forces are pushed to the edges of the continent, and in mid-2020, a multinational army that has massed in Britain stages an amphibious invasion across the English Channel to retake the lost territory. The infantrymen wear powered combat exoskeletons that they call “Jackets,” and which give them super-strength and let them carry heavy weapons. Tom Cruise plays an American officer who is part of the first wave of the invasion.

The operation is a disaster: thousands of mimics are secretly entrenched in and around the French beach where the humans land, and the human soldiers’ advanced technology doesn’t save them from annihilation. Tom Cruise survives only a few minutes of combat before he detonates a bomb at suicidally close range to kill a mimic that is attacking him. That mimic is unusually large and is colored differently from all the others, the explosive blast tears it apart, and Tom Cruise is sprayed with its blood, which enters his body through his mouth, eyes, and open wounds also caused by the explosion. Seconds later, he dies of his injuries, but then awakens roughly 24 hours earlier, with his injuries healed and his memories of that horrible day intact.

No one else is aware of the time reset, and people who Tom Cruise saw die on the beach are alive again at the base, unhurt and clueless. When Tom Cruise tells his commander about what happened, he is dismissed as crazy, and is forced to participate in the amphibious invasion again. Events replay as calamitously as the first time, a mimic again kills Tom Cruise, and he wakes again, 24 hours earlier, this time with memories of TWO beach invasions that he fought in.

This sequence of events repeats itself several times without Tom Cruise understanding why, and with him experimenting with different tactics during each cycle. On one of the days, he meets a soldier played by Emily Blunt, and she explains the source of the time reset ability.

The mimics consist of three species: 1) Drones, 2) Alphas, and 3) the Omega. The drones are expendable foot soldiers and are by far the most common type of mimic. The alphas are the battlefield commanders and look like larger, blue versions of drones. There is one alpha for every 6.8 million drones. The Omega is an enormous, stationary life form that kind of looks like a nightmarish flower with its petals partly enclosing a sphere, and it can reset time to a point about 24 hours earlier. All of the mimics are telepathically connected and share a “hive mind.” Whenever an alpha dies, the Omega immediately senses its loss via the psychic link, and it resets time. That dead alpha, along with any other mimics that died between intervals, is resurrected, but with intact memories of what happened in all the previous time cycles.

This setup is the basis of the mimics’ combat prowess because it lets them experiment with different strategies and tactics against their human enemies without risk of losing. If a mimic attack is defeated and the alpha leading that attack is killed, then a time reset happens and the mimics attack again, but adjust their battlefield tactics to overcome or avoid whatever caused their defeat previously. This process is repeated as many times as is needed for the mimics to win. It’s no different from a video game player saving his game right before a challenging battle against an NPC enemy that he knows will probably kill him, and then repeatedly reloading the game from that save point to fight the boss over and over until he finally wins. During each battle, the human player learns a little more about his enemy’s strengths, weaknesses, and tactics, and attenuates his own fighting style accordingly.

When Tom Cruise died on the beach the first time, the alpha’s blood entered his bloodstream, infusing Cruise with the same telepathic link to the mimic collective, and with the ability to make the Omega reset time whenever he dies. With this knowledge, Tom Cruise partners with Emily Blunt to find a way to kill the Omega, regardless of how many time cycles it takes to locate it and find its vulnerability. Without the time reset ability, the remaining mimics will be slowly destroyed by human military forces.

I thought Edge of Tomorrow was a respectable movie overall. It was entertaining, had great special effects (the alien design and their social structure were very creative), and for an action sci-fi film marketed at mass audiences, its plot was surprisingly complex. It was neither one of the best nor worst films of the genre, but I still recommend it.

Analysis:

There will be powered combat exoskeletons. Along with the aliens, the defining sci-fi element in the film is the powered combat exoskeletons. The outfits, which are called “Combat Jackets,” give their wearers super strength, enormous firepower, and provide some ballistic protection (though the value is questionable since the aliens’ bullets and sharp tentacles seem to always penetrate it). The exoskeletons are also powered by single batteries about the size of VHS tapes. Exoskeletons like these doesn’t exist, there are no signs they will be created anytime soon, and I have doubts they will ever be practical for battlefield use.

The main reason why combat exoskeletons don’t exist is lack of a portable power source for them. It takes a lot of energy to move around heavy metal arms and legs, all while bearing the weight of weapons, armor and other equipment attached to the exoskeleton, as well as the weight of the human operator’s body. To put this into perspective, one of today’s most advanced exoskeletons, the “Guardian XO” made by Sarcos Robotics, needs a battery pack the size of a large briefcase to operate for eight hours. Since that figure hasn’t been independently verified and is instead being claimed by Sarcos without any supporting data, the actual operating time on a single charge is probably significantly lower. Additionally, the Guardian XO is intended for use in controlled factory environments where the operator mostly stays in one place and slowly lifts heavy objects up and down. In a combat situation where the wearer would be sprinting, jumping, marching long distances, and rapidly moving their arms and pirouetting their bodies to aim weapons at enemies, the rate of energy consumption would be much higher. If you wore a Guardian XO into combat, the machine might be out of juice in three hours, turning into a useless, heavy encumbrance you’d have to wriggle out of like a wrecked car.

You can’t take a big piece of personal equipment into battle if you know it will stop working after a short time, putting your life at risk. That said, I don’t think combat exoskeletons will be worth considering until they’re able to run at least 24 hours on a single battery that is no bigger than the Guardian XO’s backpack. This would probably require batteries that are at least five times more energy-dense than today’s standard lithium-ion batteries, meaning growth from 260 Wh/kg to 1,300 Wh/kg, which is as energy dense as gasoline. I’m not sure if chemistry even allows for batteries or “battery-looking” solid media like fuel cells and capacitors to be that energy-dense AND stable, but assuming it is, then we should achieve this level of technology in 33 years if the long-term 5% average yearly rate of battery improvement continues (recall that I’ve predicted battery-powered airplanes will become practical around the same time).

Even if the power supply problem were solved, there are more potential deal breakers that could keep combat exoskeletons from the battlefield. The risk of accidental injuries to wearers and their comrades might prove unacceptable. If you tripped over a log and face-planted on the ground in just the wrong way, the weight of your big backpack battery and portions of your metal frame could snap your neck. If you were wearing a 200 lb, rigid metal suit, and you fell backwards while climbing a hill and rolled over the un-armored people behind you, it could be a multi-casualty, mission-ending disaster. Simply swinging your super-strong, metal-encased arm out to the side could send an unseen comrade to the hospital if it accidentally connects with his face.

The risks of self-injury to wearers could be mitigated if the exoskeletons fully enclosed the wearer’s body. For example, head and neck injuries could be prevented if the exoskeleton had an integral, full-head helmet, like the atmospheric diving suit shown above. Since it must withstand the crushing pressure of the deep sea, the clear visor is doubtless very strong and can be thought of as an integral part of the rigid exoskeleton suit. If the man were wearing the suit and he fell forward while waddling around a parking lot and his faceplate landed on the curb, the force of the impact would be absorbed by the whole exoskeleton, not transmitted into his face and neck, and his injuries would be minimal. Likewise, if a squad of soldiers were wearing powered exoskeletons like that, then the risks of them accidentally hurting each other would be much lower since each man’s armor would absorb the force of accidental physical contact with the other men. Being fully enclosed in heavy armor also has obvious value blocking enemy bullets.

Problematically, a fully enclosed exoskeleton would be heavy and would introduce the new problem of overheating the wearer, in turn mandating the incorporation of a body cooling system. The extra weight of the armor and cooling system and their drain on the exoskeleton’s power supply could easily plunge the whole system into an engineering “death spiral” of irreconcilable requirements. Additionally, full-body armor would make it hard for the wearer to move around his limbs, limiting his ability to aim his weapons and even just to walk. Crouching down to avoid gunfire would be harder, and getting into a prone position might become impossible, which would be unacceptable. And if the exoskeleton were too bulky, the wearer wouldn’t be able to fit through the doors of standard military vehicles, and he might get so wide that he’d take up two seats, forcing the deletion of another member of the infantry squad (is one soldier in an exoskeleton better than two soldiers without?). Treating an injured comrade while he was stuck in his exoskeleton would also be challenging and would add to the “user risk” problem. These tradeoffs probably wouldn’t make it worth it to put average soldiers in fully enclosed exoskeletons, or even “mostly enclosed” ones.

With these facts in mind, I’m left unsure if it will ever make sense for humans to wear powered combat exoskeletons into battle. If it does make sense, then the most realistic type would probably be a minimalist exoskeleton meant to increase the amount of weight a human soldier could carry on patrols. It would have boots connected to segmented legs, in turn connected to a metal frame supporting the wearer’s hips and back, similar to the real-life “EksoGT” shown above. Instead of a soldier slinging a heavy backpack over his shoulders and getting physically exhausted during a march by straining against its weight with each step, the soldier could put on an exoskeleton and attach the backpack to the suit’s metal frame. The weight would be borne entirely by the frame, allowing the soldier to go on long patrols without getting as tired, and to carry more gear than would otherwise be possible.

These kinds of exoskeletons could also allow wearers to carry and fire weapons that are too heavy for unaided humans to bear, like .50 cal machine guns and automatic grenade launchers, giving their infantry squads a huge increase in firepower. Instead of adding two robot arms to the exoskeleton to let the wearer carry such heavy weapons, it might make more sense to copy the infantry kit setup from Aliens and to attach a Steadicam rig to the exoskeleton’s frame, and then use the tip of the Steadicam as the weapon’s mounting point.

Minimalist exoskeletons like this wouldn’t have the potentially dealbreaking weaknesses I described earlier. Since they would be lightweight, they wouldn’t pose serious injury risks to comrades if a soldier wearing one of them accidentally stepped on someone else’s foot or fell on top of them. The low weight also means the battery pack’s size and lifespan would be practical for field use. Since the exoskeletons wouldn’t enclose their wearers in armored shells, overheating wouldn’t be a problem, and cooling systems would be unnecessary. Since they wouldn’t give their wearers super-strength, there would be no risk of accidental injury from that source. And so on…

Still, there would be important limitations. Battery life limitations would prohibit the exoskeletons from being used on multi-day missions where logistical support (e.g. – someone else giving you fresh batteries) could not be guaranteed. Thus, I think they would only be used for missions expected to take less than 24 hours, like daylong patrols where the plan was to go back to a base at the end. Another limitation is that wearing an exoskeleton would hurt the soldier’s mobility in some ways: Certain leg movements like crouching down and walking laterally would be harder to do. The weight of the exoskeleton and of any objects strapped to it could make it harder for the soldier to stay balanced on his feet. Overall though, the benefits could outweigh the downsides.

The other type of exoskeleton that might make sense is a fully-enclosed, heavily armored suit meant for quick, pre-planned raids, like the attack on Osama bin Laden’s house, or rescuing hostages from a building full of militants. In those kinds of missions, the extreme risk of close-quarters gunfire would demand full body armor, and it would be so heavy that only a powered exoskeleton could bear it. The concordant reduction in battery life wouldn’t be a problem due to the shortness of the combat–it would only need to work for an hour before the bad guys were all dead and the friendly troops were extracted. Super-strength would also be of real value given the chance of hand-to-hand combat in close quarters. The psychologically intimidating effect of attacking people while wearing a suit of heavy armor would also be beneficial. And if all the commandos were wearing exoskeletons, they wouldn’t be able to accidentally hurt each other.

In summary, I predict that combat exoskeletons could be practical and in common use among the most advanced militaries and military/police commando groups as early as the 2050s. At least 30 years will be needed to batteries to improve enough to make them practical for field use, and for other technological kinks to get worked out. Powered exoskeletons designed for less critical tasks, like factory/construction work and aiding people with spinal cord problems, will become practical earlier.

Humans in powered combat exoskeletons will dominate warfare forever. OK, so Edge of Tomorrow only shows a snapshot in time–an alternate 2020–and doesn’t tell us whether exoskeleton soldiers will still be the apotheosis of ground warfare in 2040, 2100, or the year 3000. This means I’m putting words in the film’s mouth in a sense, but this is an important point I need to bring up somehow: Even if the exoskeletons get really, really advanced and powerful, they will inevitably be rendered obsolete by unmanned weapons. This is because the central component of an exoskeletoned soldier is a human being with a flimsy body made of flesh and bone, and who needs hours of sleep and rest per day. As I discussed in my Terminator Dark Fate review, humans will inevitably become the weakest links in all combat systems, and will thus be inferior to all-mechanical counterparts.

A scene from Edge of Tomorrow illustrates this point. During the invasion, Tom Cruise and his squad ride to the beach in a cargo helicopter. The plan is for the craft to drop to low altitude and hover over the beach while its belly opens up like a bomber and the troops dismount by rappelling down to the sand on ropes. Unfortunately, enemy ground fire critically hits the helicopter a minute before the planned disgorging of its load, so Tom Cruise and the others have to jump out of the stricken craft at higher altitude or die in an explosion. There’s then a spectacular jump sequence that ends with Tom Cruise free-falling about 30 feet to the ground, slamming the front of his body and face into the wet sand. He is shaken by this, but unhurt, and the same is true for his comrades who fell the same distance.

In reality, the fall would have hurt Tom Cruise and several of the others so much that they wouldn’t have been able to get up and fight. Even though the exoskeletons were made of strong metal that might not have been scratched by the impact with the ground, the bodies of the humans inside the exoskeletons were made of weak flesh and bone, which would have been damaged by the abrupt change in velocity. Machines can be much more durable than the soft humans that are being flung around against the hard surfaces inside of them.

The frailties of the human body are already the limiting factor of fighter plane performance. When a plane makes a sharp left or right turn, the aircraft and the pilot experience G-forces (you also feel it when you make a sharp turn while driving your car). As shown in the graph above, the intensity of the G-force has an exponential relationship with the sharpness of the turn (“Bank Angle” expresses how sharp the turn is). A human pilot can’t withstand more than 9 G’s before he passes out from the physical strain on his body, but his aircraft can endure 15 G’s before its metal parts break apart. This means the human effectively limits the aircraft’s performance below its theoretical maximum, and by extension, it means that, in a dogfight, an autonomous fighter plane with a computer pilot could outmaneuver a human-piloted fighter plane.

Humans are becoming the weakest link in fighter plane combat, and farther in the future, we will also become the weakest links in ground combat. That means humans in combat exoskeletons will be inevitably rendered obsolete by some kind of purely mechanical fighting machine that isn’t hurt by 30-foot falls, doesn’t feel fear, doesn’t need to sleep, and doesn’t have fleshy eardrums that can be blown out by nearby explosions and heavy gunfire. There may be a period of time where humans in exoskeletons are the pinnacle of ground warfare, but this will give way to an era of full mechanization.

Human soldiers will use powered exoskeletons for hand-to-hand combat. In several scenes, soldiers use their exoskeletons’ mechanically amplified strength to punch aliens and objects with superhuman force. Tom Cruise kills at least one alien this way, and his girlfriend uses her strength to casually punch a car door out so it detaches from its hinges and skids across the ground. If powered combat exoskeletons become common, few of them will grant users amplified hand-to-hand fighting abilities like this.

As I wrote earlier, powered combat exoskeletons will probably be used to bolster the endurance and load-carrying capacity of infantrymen. Exoskeletons designed for that would not necessarily have features that also let the user punch or kick things with greater than normal force. For example, since my minimalist exoskeleton lacks arms, it wouldn’t empower its wearer to punch harder or lift heavier things. The Steadicam mount would be like a strong, third arm that could prop up guns but do nothing else that a human arm does, like punching.

Even if exoskeletons amplified their wearers’ strength, it would be of very little direct benefit in combat since hand-to-hand fighting is extremely rare on the modern battlefield, and there’s no reason to think that will change in the future. If anything, average kill distances will increase thanks to smarter weapons. Endowing soldiers with the ability to punch and kick with superhuman force would also make accidental injuries to oneself and nearby comrades more common and more severe, potentially outweighing the small benefits of being able to strike enemies harder.

Superhuman strength will probably only be useful in the “fully-enclosed, heavily armored suit meant for quick, pre-planned raids” that I envisioned earlier. A squad of men wearing such suits wouldn’t be able to accidentally hurt one another with their super-strength since their full-body armor would protect them. Hand-to-hand combat would also be much likelier in the kinds of close-quarters missions the suits would be used for, making super-strength a real advantage.

Let me finally note that I liked how Tom Cruise’s exoskeleton enclosed most of his hand in a big, metal “glove.” It was a small but important detail, since it let him punch things without crushing all the bones in his hand. The front of the rigid, metal glove connected with the surface of whatever he was punching, and the force of the impact was transmitted from the glove to his suit’s metal arm, and then into the metal torso portion of his exoskeleton, meaning the frame bore the superhuman forces of his punches, and none of it was transmitted into the soft tissues of his body, sparing him injury. Exoskeleton suits designed for augmented, hand-to-hand combat would need to enclose their wearers’ hands and feet to prevent operator injury.

There will be tilt-engine aircraft that are bigger and better than the V-22. In the film, the human military has large utility aircraft with four engines that can tilt, transforming the aircraft from helicopters into planes. They use many of these tilt-rotor aircraft to transport the exoskeleton troops to the battle zone. These kinds of aircraft don’t exist, the best we have in real life is the much smaller V-22 (which only has two tilt-engines), and I doubt anything like the aircraft shown in the film will exist for at least 20 years.

Consider that the V-22 development program started in 1982, the first prototype wasn’t made until 1988, and internal testing and redesigns went on until 2005, when the aircraft’s kinks were finally worked out and it entered mass production. In other words, it took 23 years for the V-22 to go from formal concept to a combat-ready aircraft (and that label is debatable since it suffered from serious problems after 2005 that took more time to fix).

If we wanted to build a new tilt-rotor aircraft that was bigger and more complicated than the V-22, then the latter’s 23 year development timetable provides a benchmark for how long it would take. If the aircraft used a more advanced type of propulsion, like the tilting turbofan engines the Skynet’s planes had in Terminator, then it would be even longer. Granted, if we were invaded by aliens and desperately needed better weapons, the project would get more money and manpower and would go faster. It’s also possible that some development time could be shaved off by carrying over engineering and project management lessons learned during the V-22’s development. That said, even if we had all our ducks in a row, I doubt we could make such an aircraft in less than ten years. Returning to the real world, we are not grappling with an alien invasion and no major country is planning to sharply increase its military R&D budget, so the ~20 year timetable to go from a government announcing it is willing to pay money for an advanced aircraft with XYZ characteristics to a fully functional aircraft is most likely. This means there won’t be anything like the quad-tilt-rotor aircraft in Edge of Tomorrow until 2040 at the earliest.

It will probably take longer than that since the 20 year end date assumes that the development process starts now, in 2020. In fact, no military has announced a serious desire for such an aircraft, nor does any look poised to do so. The V-22 still hasn’t proven its worth, and history might someday look on it as an expensive failed experiment like the Concorde or the Space Shuttle. Until it does so, there will be no demand for even bigger, more expensive tilt-rotor aircraft. (Note that the U.S. military has a program called “Future Vertical Lift,” whose goal it is to make tilt-rotor aircraft that are smaller than the V-22. It may or may not be cancelled.)

There will be 3D volumetric displays. In one film scene, the characters look at a tabletop volumetric projection of their alien opponents. The display is highly detailed, runs silently, and is treated with some disinterest, indicating it is an established technology. As I wrote in my Prometheus review, the current state of this technology is underdeveloped, and it will be many decades before the kinks are worked out and it becomes practical. Even once it becomes a mature technology, it could be muscled out of use by competing technologies.

Links:

1. Article on the “Guardian XO” powered exoskeleton. https://www.sarcos.com/company/news/media-coverage/xo-rbitant-strength-electric-exoskeletons/
2. A video report about the Guardian XO. https://youtu.be/zLWuHo63C8k
3. A hands-on analysis of a Steadicam gun support rig. https://www.thefirearmblog.com/blog/2018/04/04/steadicam-third-arm/
4. A 30-foot fall can easily kill a person, and usually causes significant injuries. https://www.usatoday.com/story/news/health/2017/06/26/can-you-survive-25-foot-fall/428384001/