Science in Fiction

Science in Fiction

27 January 2011

Despicable Me: Shrink Ray

Let us watch the following video and dissect the science of the shrink ray.

The Shrinking:

Let me begin with some background.  Everything we can "touch" is matter.  In this clip, Gru is matter, the minions are matter, the ship is matter, the air is matter, Vector is matter, the shrink ray is matter, the clouds are matter, Gru's scarf is matter... I think you get the point.  And matter is made up of atoms.  And atoms maintain a certain size.  For all intents and purposes, we can assume that an oxygen atom will be the same size as all other oxygen atoms.  Therefore, atoms cannot "shrink" in size.

This leads me to assume that if something were to shrink, then it would contain less atoms.  Therefore, the post-shrunk object has fewer atoms than the pre-shrunk object.  But we don't see any atoms.  Do they just go away?  Disappear?  Bleep out of existence?  Not possible.  This would violate the law of the conservation of mass.  If you don't know what mass is, think of it as (I'm colossally simplifying the idea) mass is a how much of you there is (e.g. you weigh 120 lbs, so your mass is 54 kg).  So, the law of conservation of mass just means that what goes in, must come out.  So, if we have x many atoms before shrinking, then we should still have x many atoms after shrinking.  Which leads to the following example.

Let's say we hit a minion with some shrink rays.  This minion should then become a mini minion and some spare atoms.

atoms not accurately portrayed

We can use this for any shrunk object:
shrink rays + object = spare atoms + mini object
object atoms = spare atoms + mini atoms.

So, where are our missing atoms?  Well, apparently, they are not far.  If you have seen the movie, then you know that the shrunk objects don't stay shrunk for long.  They just pop right back to the normal size...........  I have no idea how this happens.

Now, I'm going to back track a bit to pose the following question:  If the atoms could shrink, is the mass the same?  If it is, I would assume that the gravitational pull is the same.  Gravitational pull is what causes things to fall to earth.

Now, in the movie Gru shrinks the moon.  The moon's gravitational pull is strong enough to cause tides, the rising and lowering of the ocean water, on earth.  And if your standing on the moon, you stay on the moon.  You don't go flying off into space or tumbling back to earth.  In short, the moon has a noticeable gravitational pull  The moon's mass is 70,000,000,000,000,000,000,000 kg.  That's 1,000,000,000,000,000,000,000 150 lbs people, reduced to the size of a baseball.  Yikes. So, I'm wondering how he manages to capture it and carry it around with him.  I have no answer for this.

Some things to think about:

In the video, the shrink ray shrinks the plane.  But the plane isn't one thing.  It shrinks the metal plates, the rivets, the glass, the electronics, etc. but it doesn't shrink Gru and the minions.  So, how does the shrink ray select what it shrinks?

What are the shrink rays made of?  How does it induce shrinking?  Is it a chemical reaction?

Any other scientific inconsistencies with the shrink ray?


  1. Anonymous20/5/12 16:22

    Your blog was so helpful!! It really explained everything I needed to understand for a school presentation. Thanks!! Great work. Very easy to understand. :)

  2. I love your blog :-) :-) Your blog is great! But i think you made mistake here. You say about atoms: "Do they just go away? Disappear? Bleep out of existence? Not possible." But actually it is possible that mass can "vanish" (anihilate is more physics word) and turn into energy (according to Einstein's E=mc^2). Yeaahhh... this will be a lot of energy and all will be blows up. So this scenario is also impossible.

  3. I have always thought of the shrink ray only hitting one atom or thing, so theoretically the ship would lose one bolt, or that wall (or plate).
    I know that gru probably welded these plates together but, what about the stuff inside his ship? It is connected by wires, but not permanently.

  4. what your saying is not entirely correct it would be possible to shrink and atomic structure by simply changing it's gravitational pull.
    Lets start by looking at the quantum structure of an atom,
    there are protons pulling inward and Neutrons balancing out the mass of the nucleus and electrons spinning around the nucleus. However, they are not spinning close to the nucleus.
    If you were to blow up an atom's nucleus to the size of a marble depending on what type it was the closest Electron spinning around it would be some 50 miles away maybe even further depending on the atomic structure. so you see the largest percent of an atomic structure is empty space.
    If we decrease the gravitational push of the nucleus and increase the pull of the electrons the atom would start to collapse in size and in fact if I did that enough I could get the electrons within feet, or even inches of the nucleus rather than miles or even hundreds of miles.
    If I did this to all the Atoms in an object that object would shrink in size however it would also become a very very dense atomic structure. Like you said the mass of the object wouldn't change it would just be more tightly packed this would have some interesting side effects ...
    the first most noticeable would be so many electrons so tightly packed would be producing a "ridiculous" amount of heat. It would probably be so hot you couldn't get within a thousand miles of it. this would lead to the sloughing of electrons as they were trying to escape such tight confinement ... if enough electrons escaped at the same time you would have an explosion of world creating proportions.
    the second would be that it would be just as heavy as it was before you shrunk it. again like you said the mass wouldn't change so the small it became the more intensely focused the weight would become therefor if you shrunk a buick in your driveway to the size of a matchbox car you still wouldn't be able to pick it up with out some heavy equipment.
    The gravity would would shift overall. for all intent and purpose your are basically creating a singularity that would start drawing in and crushing all the matter that got within a million or so miles of it.

    So lets re-tell the shrink ray sinaro in teh movie ... the north corieans use the shrink ray to compress teh atomic structure of an elephant ... the elepant dies in the process as all of it's mass is simotainioulsy crushed into the size of a church mouse and becomes super radioactive, within nanoseconds of the shrinking the mass that was the elephant goes white hot then ultra white hot then in a flash it goes super nova wiping out all life in the universe as we know it ...

    So to recap yes it's possible to shrink matter stars do it when they die and become black holes. I'ts not probable however nor is it a good idea...