Iron Man is one of Marvel’s best loved heroes, and Robert Downey Jr. brings him to life in true Tony Stark style. Since his first appearance in the ’60s, Iron Man has gone through a huge amount of changes. His backstory has been retconned multiple times (to bring him, and the wars he was involved in, up to date for new readers), and his suits have grown and evolved along the way. At various times he’s battled himself, his enemies, and even his fellow heroes, but he remains a mainstay of the Marvel universe.

Throughout all of these changes, one thing has remained constant – the source of his power: the Arc Reactor. Technically, of course, Tony Stark has no superpower, unless you count his genius-level intelligence. Out of that intelligence, however, was born the Arc Reactor. After he was injured and kidnapped in a warzone, he implanted a device in his chest to keep the shrapnel in his body out of his heart. He then built a suit of iron to fight his way out of captivity, and his alter ego of Iron Man was born. Since then, the reactor has been re-worked and refined over the years, but it remains at the heart (pun very much intended!) of Iron Man.

Here are 12 Things You Didn’t Know About Iron Man’s Arc Reactor.

12. It Powers Stark Tower

stark tower sign at night 12 Things You Didn’t Know About Iron Man’s Arc Reactor


Not the tiny version that lives in Tony Stark’s chest, obviously, but a much larger arc reactor that is situated at the base of the iconic tower. Although this isn’t mentioned in the comics, it’s a major plot point in the Marvel Cinematic Universe. In the films, the larger arc reactor actually came first, as Howard Stark designed it as a source of clean, renewable energy. Although there were plans to use the reactor technology to supply energy to more of New York, this has yet to happen in the MCU (onscreen, anyway).

During the events of Iron Man, the large reactor was a key part of bringing down the villainous Obadiah Stane. In his final battle with Iron Man, Tony lures Stane to Stark Tower, where he tells Pepper Potts to overload the arc reactor, generating a pulse strong enough to knock out Stane’s armor. Although the original reactor was destroyed in this fight, it has since been rebuilt. Stark Tower became Avengers Tower after the Battle of New York, and Stark continues to laud its power source as the clean energy source of the future.

11. It Was Designed By Different People In The Comics and the MCU

Stark 12 Things You Didn’t Know About Iron Man’s Arc Reactor


Although the patent for the arc reactor is owned entirely by the Stark family and Stark Enterprises, the actual designer is different in the comics and in the Marvel Cinematic Universe. In the MCU, the arc reactor was originally designed by Tony Stark’s father, Howard Stark. A brilliant scientist and weapons expert, Howard Stark worked alongside former Soviet scientist Anton Vanko, and the two came up with the arc reactor together. However, Vanko didn’t have the purest motives for their work, and Stark had him deported, setting up a lifelong hatred of Stark Industries by the Soviet and his son, Ivan. Tony Stark then developed his father’s ideas and used them as the basis for the mini arc reactor that saved his life.

In the comics, it isn’t Howard Stark, but Tony himself who invented the arc reactor. He was originally aided by the Nobel award-winning physicist, Yin Sen, who was also a prisoner of the warlord holding him captive. The two created the electromagnetic plate, first arc reactor, and first Iron Man suit while in captivity. Later, Danny Rand (aka Iron Fist) worked on the designs as well, helping Tony Stark modify them.

10. Pepper Potts Has One Too

gwenyth paltrow as pepper potts 12 Things You Didn’t Know About Iron Man’s Arc Reactor


In the Marvel Cinematic Universe, Pepper Potts (Gwyneth Paltrow) has a relatively minor role. She is Tony Stark’s girlfriend (possibly his ex at this point, however), as well as his right hand man and CEO of Stark Industries. Although she has moved up in the world from her days of being Tony Stark’s secretary, she still hasn’t quite realized the potential that she has in the comics.

In a story similar to Tony’s own, Pepper was critically injured when a bomb went off during a dinner party, lodging shrapnel in her body. With her too weak to withstand the necessary surgery, Tony decided to implant a magnet in her chest, much like the one that he has in his, to keep the shrapnel out of her heart until she could undergo surgery. Along with various cybernetic enhancements, this allowed Pepper to survive and heal, although she will never be able to remove her enhancements. However, she embraced them (after initial fears that she was becoming too weaponized), and now wears a suit of her own and has become the hero known as Rescue.

9. It’s Immune To EMP

close up of arc reactor iron man 12 Things You Didn’t Know About Iron Man’s Arc Reactor


EMPs, or electro-magnetic pulses, have become something of a staple in action movies. An EMP is a short burst of electromagnetic energy – which sounds rather harmless, but which actually knocks out most electronic systems. In films, we have seen an EMP weaponized and used to crash planes and helicopters, stop working cars in their tracks, prevent phones and security systems from working, and generally cause all kinds of havoc (as well as remind us how much we rely on electronic systems).

This would obviously be a problem for Tony Stark, seeing as the arc reactor is a vital part of keeping him alive (by keeping shrapnel out of his heart). His reactors are also used to power his suits, so if they were susceptible to damage by EMP, his time as a superhero would be effectively over with one timely blast. Any super-villain would simply have to use an EMP device (and not require any tech themselves), and Stark would be easy to defeat. In the comics, some have tried to use an EMP against him, but while it affects the suit itself, the reactor is unharmed. This allows him to re-start the suit almost instantly, and keep going.

8. It’s Made of Vibranium (Or Is It?)

caps shield vibranium 12 Things You Didn’t Know About Iron Man’s Arc Reactor


Vibranium is best known in the Marvel universe as the material that Captain America’s shield is made from. An incredibly strong meteoric ore, vibranium is extremely rare, as it is found only in meteors that have crashed to Earth (and despite many attempts, none have been able to reproduce it). However, it has also been mentioned in connection with Tony Stark in the MCU.

In Iron Man 2, Stark is suffering from palladium poisoning courtesy of the reactor in his chest. He spends much of the film bemoaning his imminent death, as he can’t seem to see a way out. If he removes the source of the poison, the shrapnel in his body will reach his heart, and he will die. If not, the palladium will kill him. He manages to get around this by finding a message from his father, showing him how to create a new element. Tony whips up this new metal in his lab, and creates a replacement reactor with it, which cures his palladium poisoning. Hurrah!

In the novelization of the film, this new metal is Vibranium – suggesting that the Starks actually created the alien metal in the MCU. However, this has since been dismissed by Captain America: The First Avenger (released a year later), which shows that Vibranium already existed in the 1940s.

7. It Doesn’t Actually Keep Him Alive

iron man 2 palladium poisoning 12 Things You Didn’t Know About Iron Man’s Arc Reactor


The arc reactor in Tony Stark’s chest is often referred to as what’s “keeping him alive,” but it’s actually not technically what saves his life. Most people know that before Stark was Iron Man, he was a businessman in a war zone (the exact reasons for him being there depend on which version of Stark, and thus which particular war, you are dealing with), who was involved in an explosion before being captured by the enemy. He was held against his will and told to create weapons for his captors, but built himself a metal suit, instead, and used it to escape. In the very first versions of Iron Man, that was all there was to it.

However, in most versions of the character (including the current iteration), the explosion that hit Stark caused shrapnel to become lodged in his chest. When he came to, he found an electromagnet attached to his chest, keeping the shrapnel from reaching his heart and killing him. It’s therefore actually the electromagnet that keeps Tony alive, not the arc reactor. The reactor was something that Stark created so that he wouldn’t have to be attached to a giant battery, and is what powers the magnet – theoretically, any power source would do the same (but wouldn’t be nearly as cool!).

6. After Iron Man 3, Tony No Longer Needs It

iron man 3 tony stark surgery 12 Things You Didn’t Know About Iron Man’s Arc Reactor


Despite the fact that it’s not the arc reactor itself, but the electromagnet that it powers that keeps Tony alive, in the MCU he no longer needs either to survive. At the end of Iron Man 3, Tony undergoes an operation to remove the shrapnel from his chest and remove the arc reactor completely. In a dramatic gesture, he even throws it into the ocean (after it is decommissioned, of course). He reappeared in Avengers: Age of Ultron with his suit on and the iconic glowing blue circle on his chest, but at this point, miniature arc reactors are only powering his suit, not keeping him alive.

Many fans questioned why it took Tony so long to get the shrapnel removed – after all, one would assume that that would be his first move upon returning home and having access to qualified surgeons. However, it was shown in the Chinese cut of the film that Tony met with a cardiologist who was the only one capable of performing the operation – which explains why he hasn’t had it done previously.

5. It Could Also Be Used As A Bomb

iron man arc reactor close up 12 Things You Didn’t Know About Iron Man’s Arc Reactor


Inspired by fusion power and a source of immense energy – it’s not surprising to learn that the arc reactor technology could be easily weaponized. (That is, weaponized more directly than as the power cell for iron suits.) This is one of the reasons that Tony is so careful with the details of the technology, and refuses to make it readily available, even though it could potentially provide the world with a sustainable source of clean energy. His fear is that others would use his technology to create immensely powerful explosives, and he has gone to extreme lengths to prevent others from getting their hands on it.

Despite his great secrecy, and even his inclusion of a fail-safe that allows him to remote-detonate his suits if they are captured, many are still worried that the arc reactor would fall into the wrong hands. Realizing that he had to do more to protect the world from his own tech, Stark approached Danny Rand (Iron Fist) for help. The two worked on the reactor, and made several modifications that prevent it from ever being used as a bomb.

4. Reactors Power His Suits (And Haven’t Always Provided Unlimited Power)

iron man in a storm suit 12 Things You Didn’t Know About Iron Man’s Arc Reactor


Although Tony no longer needs his mini arc reactor to survive (in the MCU), we can still see its signature blue glow in the center of his chest when he is suited up as Iron Man. Because while it doesn’t power an electromagnet in his chest any more, it still acts as the primary energy source for his suits. He also uses repulsor tech nodes (another name for the arc reactor) to power many of his other gadgets, including his Repulsor Car.

Although the arc reactor is immensely powerful, it isn’t actually an unlimited source of power. While it is possible for the miniature reactor to power the electromagnet that was in Tony’s chest for the rest of his lifetime, the various Iron Man suits use a lot more juice than a small electromagnet, and occasionally need to re-charge. We saw this in the movies, when Tony is shown charging his suit using a truck battery, but he could theoretically use any power source. In the comics, he has actually used multiple different energy sources to recharge his suits, and many of his suits also collect solar energy so that he doesn’t run out of juice mid-battle.

3. A Real-Life Version Is In The Works

arc reactor blueprints 12 Things You Didn’t Know About Iron Man’s Arc Reactor


While there are plenty of cosplay versions of the arc reactor, that’s not what we’re talking about here. In fact, MIT (among others) has been working on building a reactor that would function like the Marvel arc reactor (although we assume that they wouldn’t actually use that name. Sadly.). The folks over at MIT’s Plasma Science and Fusion Center have been making leaps forward in this attempt, which means that we could see arc reactors powering cities relatively soon!

The basic principle of the arc reactor is that of a fusion reactor, and it’s the size that makes it really impressive. While MIT is nowhere near making a donut-shaped fusion reactor as small as Tony Stark’s, their latest efforts have been to create a tokamok-type nuclear fusion device that would only require a 3.3 meter radius – yet which would put out 500MW of power using only 50MW, thanks to superconductor technology. If their design works, it would be enough to power 200,000 homes – which is even better than a single super suit.

2. Others In The Marvel Universe Have Failed To Replicate It

robert downey jr iron man reactor showing through shirt 12 Things You Didn’t Know About Iron Man’s Arc Reactor


Unsurprisingly, multiple other Marvel characters have attempted to recreate both the arc reactor, but all attempts so far have failed. Obadiah Stane was one of those to attempt to steal Stark’s technology, both in the comics and in the films. He built his own suit (becoming the Iron Monger), but was incapable of replicating the repulsor node technology that Tony Stark held. After tangling with Stane, Tony worked on ways to prevent others from replicating his armor, even disabling Mandroids (SHIELD armor) which he had given to them. The US Government has repeatedly attempted to replicate Stark’s tech, including a suit which they nicknamed Firepower (and which War Machine eventually took down).

Despite the fact that Tony is incredibly protective over his technology, he has allowed others to make use of it – just not to know how it works. As well as Pepper Potts, he has created a range of suits, including several worn by other characters. In the MCU, he encourages people to look to the arc reactors as the energy source of the future, although presumably the details of the device would remain a secret, even if every city was powered by them.

1. Movie Magic: Pepper Potts Operation Used The Same Effects As Star Trek’s Borg Queen

pepper potts replacing arc reactor 12 Things You Didn’t Know About Iron Man’s Arc Reactor


There are obviously plenty of stunningly cool special effects in the Iron Man (and Avengers) franchise. Flying! Giant battles with aliens! Armor that builds itself onto his body! The majority of these effects come to us courtesy of the magic of CGI, but quite a few of the amazing things we have seen on screen make use of good-old-fashioned practical effects.

In Iron Man, there’s a scene where Pepper Potts is called into Tony Stark’s lab to help him out. After returning home, he’s developed a new, much more powerful (and generally better) version of the arc reactor that he first built in the cave in Afghanistan, and he needs her help to install it. What follows is a tense few moments, and a close up of Pepper working on Tony’s chest, which has a deep hole it in where the reactor sits. This was filmed using a prosthetic chest –  the fake was created with the hole for the reactor, and Robert Downey Jr was sitting in the seat at a completely different angle. The fake chest then appeared to be his own when lying down. A bright light was shone on the area to create shadows that would hide any obvious edges from the viewer (and it worked!). This is the same technique that the FX crew on Star Trek: First Contact for our first look at the Borg Queen.

Is the Arc Reactor really gone for good in the MCU? Did the surgery scene from Iron Man fool you too? Let us know in the comments.