Warning: There is going to be math later. (I’ll try to make this deduction as fun as possible!) To business –

### Immovable, Unstoppable

In Frank Herbert’s *Dune*, there exists protection that cannot be penetrated in the form of shields. Shields are immovable, covering everything from people to planets. This led to the end of ranged warfare as we would know it in *Dune*‘s universe.

There also exists “lasers” (let’s call them “phasers” for now) when fighting at a distance is called for. Phasers can cut through anything and might be considered as an unstoppable force.

When shields and phasers interact – that is, when the immovable meets the unstoppable – a huge explosion results:

A lasgun-shield explosion was a dangerous variable, could be more powerful than atomics […]

–Dune

Hearing this, I got to thinking. What kind of explosion are we talking about?

To find out, let’s first define our terms:

- Phaser – We’re going to consider this as equivalent to the
*Star Trek*phaser. Those tools were also able to cut through anything and more, dissolving entire mountains in the early pistol-size variant. - Shield – Here we assume that to stop any force, there must be an equal and opposite force. In the case of a phaser, we assume its disintegrating ray would be sent directly back along the line of the ray. Anything hitting the shield would disintegrate itself.
- Atomic – A nuclear weapon. For our purposes, assume 15 kilotons of explosive power (this was the power of the first atomic bomb in history).

### Here comes the math…

So we shoot our phaser at a shield. At the speed of light, the shield deflects the beam back at us. Our ray hits and dissolves the matter in our phaser. All that matter has to go somewhere, right? With E=MC^2 (energy equals mass multiplied by the speed of light squared), we know that:

- Energy (in Joules) = ?
- C-speed of light squared = 9 x 10^16 meters^2 / seconds^2
- Mass of a phaser = .340194 kilograms (assuming 12 ounces)

Therefore:

- .340194 kilograms x 9 x 10^16 meters^2 / seconds^2
- = 3.061746 x 10^16 Joules

A kiloton (measured in the mass of TNT-equivalent) is 4.18 x 10^12 Joules. We can cancel a few things out:

- 3.061746 x 10^16 ÷ 4.18 x 10^12
- = 3.061746 x 10^4 ÷ 4.18
- = 30617.46 ÷ 4.18
- = 7324.7512 kilotons

The energy held inside the matter of our handheld phaser is approximately 7324.7512 kilotons. To put that into perspective, **that’s more that 488 atomic bombs.**

Let’s assume a 0.03% efficiency in converting mass into energy (equivalent to modern atomic weapons; not the most efficient conversion we can implement). **That’s still some 15 atomic bombs going off. In your hand.**

Little wonder the characters in *Dune* wouldn’t bring a gun to a knife fight.