The Marvel Cinematic Universe is perhaps the most well-known film series in cinema history. Having grossed $22.5 Billion, the Disney-owned franchise boasts record-breaking box offices and incredibly high audiences, overtaking the likes of Star Wars and Harry Potter. And more than any other big film series, it is a cumulative experience, building up towards the third and fourth Avengers films. These films are centered around Thanos and his quest towards balancing the universe, by acquiring the six Infinity Stones and snapping his fingers. These include Space, Time, Power, Reality, Mind and Soul. Most of these stones have an iconic scene portraying their usage. Some of them are also somewhat accurate, scientifically speaking. Others, perhaps not so much.
In ‘Guardians of The Galaxy,’ we get an explanation from the Collector that “before creation itself, there were six singularities. Then the universe exploded into existence, and the remnants of these systems were forged into concentrated ingots… Infinity Stones.”
Singularities are mathematically where a function is undefined, or when a quantity becomes infinite. When thinking about singularities, an obvious instance is in gravitational singularities, where the curvature of space-time is infinite due to the infinite mass breaking the rules of space-time. General relativity predicts that any object collapsing on itself beyond a certain point would form a black hole, inside which a singularity (covered by an event horizon) would be formed. The initial state of the universe, at the beginning of the Big Bang, is also predicted by modern theories to have been a singularity. The universe did not collapse into a black hole, because density limits for gravitational collapse are usually based on objects of constant size, such as stars, and the Big Bang doesn’t apply as it is ever expanding. So, to this extent, the Collector’s explanation is reasonable.
Perhaps the most accurate would be the Space Stone, with multiple appearances throughout the cinematic universe, from ‘Captain America: The First Avenger’ all the way to Thanos stopping Loki’s dagger in Infinity War. An obvious explanation for its property of space travel could be of wormholes. A wormhole is a speculative tunnel between two disparate points in spacetime and is a solution of the Einstein field equations. And there is an example of a singularity wormhole, called the ring singularity, or ringularity for short. This means that it is in fact possible that the space stone could be using a traversable wormhole-esque manner to transport its users. Another thing we see Thanos using the space stone doing is stopping people in their tracks. Yet this surely has nothing to do with space, one might ask. But momentum is related to space when it comes to physics, as shown in the first Captain America film, when the space stone is weaponised into force beams.
One of the most memorable scenes involving the Power Stone is when Thanos brings down a moon onto Iron Man. The stone grants the wielder the ability to release energy. This happens to be exactly what black holes do, being the most efficient way to convert mass into energy, apart from rare matter/antimatter reactions. Einstein’s famous equation E = mc2 showed an equivalence between mass and energy. The c2 shows that it is possible to get huge amounts of energy from tiny amounts of mass, and the Power Stone is quite small, so this checks out. Black holes can release more than 40% of massive objects’ mass-energy as the object goes towards the event horizon, colliding with gas and dust, causing it to heat up and radiate energy. It must have hurt when Thanos pushed the stone onto Thor’s head.
The Time Stone, possessed by Doctor Strange, allows time travel, as well as the ability to slow down or speed up, or even forward time travel. The latter is easier to both explain and comprehend; it could be the result of gravitational time dilation. Time dilation, explained very well by Jasper Hersov here https://etonstem.com/on-the-essence-of-time, essentially causes people to experience the passing of time at different rates. The immense gravitational field surrounding a singularity causes clocks at different locations in space to show different times. This was predicted by Einstein in his theory of relativity and has since been proved by several experiments by placing clocks at different altitudes (and thus different gravitational potential) and measuring the time difference, often in mere nanoseconds. But at such a large scale, it can cause what is, on the large screen, an epic scene. Scientists try not to explore time travel too deeply, a sector with not much knowledge, as it can create all sorts of paradoxes. That may be why the concept is so different in different blockbusters, and often poorly explained. There are certain theories in which time travel is possible, but most require either some unknown exotic matter used for traversable wormholes, or involving some multiverse theory, which provides a resolution to the grandfather paradox. So, time travel is perhaps less likely to be possible.
‘Reality is often disappointing, but now reality can be whatever I want’ is a line, milked far too much, from Thanos, after he acquires the Reality Stone. But could this really be possible? Well, at singularities, the laws of physics break down, and thus reality itself. However, being able to control this, as Thanos does, seems a stretch, and without proper understanding, we cannot assume that this is possible. And the only way to achieve this understanding of singularities bending reality is through a quantum theory of gravity, which has eluded us for the past century. Once we have that, we could potentially comprehend the reality warping ability of the stone. For now, we cannot say much about how it could work.
Even more confusing are the last two stones. The Mind Stone, which grants the wielder control of the minds of others, and the Soul Stone, which gives the power to speak to spiritual dead and control souls. Both seem too far-fetched to explain, even without the restrictions of being singularities. We just don’t know enough about where consciousness originated and thus how it can be controlled to know much about these two stones.
Maybe the real question should not be whether these stones are scientifically accurate in their powers and abilities but rather how a single person can have six infinitely dense objects in their hand. Presumably, the gravitational force it has would destroy everything near it, ripping individual cells from each other. Tidal forces would disrupt other further areas of the galaxy. Yet as impossible as this seems, even for a superhero franchise, people, when watching, find no fault in it. And this is because the Marvel Cinematic Universe is so groundbreaking in its produced movies that people will not think too hard about the science behind things but enjoy the action.