The question of the strongest explosive cannot be answered with a single substance, as the term “strength” is measured in multiple ways. An explosive is fundamentally a reactive material that undergoes extremely rapid chemical decomposition, releasing a large volume of heat and gas in a fraction of a second. This sudden, energetic transformation generates a shockwave and pressure that defines its destructive power. The most powerful materials are judged not just by their total energy yield, but by the specific performance characteristics required for a particular application.
Quantifying Explosive Power
The framework for assessing an explosive’s strength rests on two primary, measurable metrics: the speed of the reaction and its resultant shattering effect. The Velocity of Detonation (VOD) measures the rate at which the shockwave moves through the explosive material itself, typically expressed in meters per second (m/s).
The speed of this wave is a significant factor in determining the energy transmitted, with high explosives detonating at speeds greater than 1,000 m/s. For instance, a common reference explosive like TNT typically exhibits a VOD of about 6,900 m/s. This rapid propagation ensures the nearly instantaneous conversion of the entire mass into a super-heated, high-pressure gas cloud.
The second metric is called brisance, which is the measure of the explosive’s ability to crush, shatter, or fragment surrounding material. Brisance is a function of the peak pressure achieved in the detonation wave and the rapidity with which that pressure is reached. It is often quantified in testing by measuring the compression of a standard lead cylinder, known as the Hess test, or through a sand crush test. An explosive with a high VOD and a high density will possess high brisance, making it effective for tasks that require intense local shattering, such as in shaped charges or munitions.
The Peak of Chemical Explosives
When focusing strictly on materials that achieve their power through rapid chemical reaction, a few compounds represent the practical limit of non-nuclear explosive strength. The benchmark for high performance is Hexanitrohexaazaisowurtzitane, or CL-20, which currently holds the highest energy density among explosives used in real-world applications. CL-20 is a cage-like molecule that achieves its performance through a combination of high density and a highly strained molecular structure, allowing for extreme energy release upon decomposition.
CL-20 exhibits a Velocity of Detonation in the range of 9,400 to 9,800 m/s, significantly surpassing the VOD of older, conventional explosives. For comparison, RDX, a common military explosive, has a VOD of approximately 8,750 m/s. Another powerful explosive, HMX, is closely related to RDX but generates approximately 60% higher detonation pressures, with a VOD around 9,100 m/s.
The superior performance of these materials is a result of their carefully engineered molecular geometry, featuring a high concentration of nitrogen-nitrogen and carbon-nitrogen bonds. These bonds release an enormous amount of energy when they break to form highly stable, gaseous products like nitrogen gas and carbon dioxide.
While CL-20 and HMX are manufactured and deployed, a theoretical compound, Octanitrocubane (ONC), is predicted to push the chemical limit even further. ONC features a cubic carbon skeleton with eight nitro groups, giving it a theoretical VOD of approximately 10,100 m/s. This strained, compact structure is predicted to be 20 to 25% more powerful than HMX. However, due to the extreme difficulty and cost of its synthesis, ONC remains a laboratory curiosity and has not been produced in quantities large enough for practical testing or deployment.
Beyond Chemical Reactions
The ultimate limit of explosive power moves entirely past the molecular scale and into the atomic realm, where the energy is released by nuclear reactions. Chemical explosives depend on the breaking of electron bonds between atoms, a process powered by the electromagnetic force. Nuclear explosives, by contrast, rely on manipulating the strong nuclear force within the atom’s nucleus through either fission (splitting atoms) or fusion (combining atoms).
The energy density of nuclear fuel is orders of magnitude greater than any chemical explosive, with nuclear reactions releasing millions of times more energy per gram. The energy released by a nuclear explosion is so vast that it is not measured using metrics like VOD or brisance, which are relevant only to localized, molecular shattering effects. Instead, the scale of nuclear power is quantified by its yield, which is expressed as the TNT equivalent in kilotons or megatons.
Modern thermonuclear weapons, which use a combination of fission and fusion, can reach yields thousands of times greater than initial devices. The destructive power of these devices is characterized by a massive blast radius, intense thermal energy, and pervasive radiation, a fundamentally different destructive mechanism than the shockwave and pressure of a conventional explosive.