The concept of “strength” often conjures images of unyielding, unbreakable materials, leading to the question: what is the strongest thing in the universe? The answer is complex, as “strength” encompasses various properties, each defining a material’s resilience. The “strongest” material depends on the type of force it needs to resist. This article explores the remarkable properties of natural, engineered, and theoretical substances, showcasing the range of resistance found across the cosmos.
Defining What “Strongest” Really Means
Material strength is not a single property but a collection of characteristics describing how a substance reacts to external forces. Understanding these types of strength is essential for appreciating why various materials excel in specific applications.
Tensile strength quantifies a material’s maximum resistance to breaking when pulled apart or stretched. Compressive strength describes a material’s ability to withstand forces that push or squeeze it, attempting to reduce its size without fracturing. This is relevant for structural components bearing significant weight.
Yield strength indicates the point at which a material begins to deform permanently, meaning it will not return to its original shape once stress is removed. Hardness measures a material’s resistance to scratching, indentation, or abrasion. The Mohs scale, ranging from 1 to 10, assesses this property.
Toughness refers to a material’s capacity to absorb energy and deform plastically without fracturing. A tough material balances strength and ductility, preventing sudden failure.
The Power of Natural Materials
Nature has engineered remarkably strong materials through evolution and geological processes, each optimized for specific functions.
Diamond, a natural carbon allotrope, stands out for its extreme hardness, ranking 10 on the Mohs scale. Its resistance to scratching comes from strong covalent bonds in a rigid, three-dimensional lattice. While hard, bulk diamond is brittle and can shatter under impact despite high compressive strength (up to 60 GPa).
Spider silk, particularly dragline silk, exhibits extraordinary tensile strength and toughness. Its tensile strength can range from 0.45 to 2.0 GPa, with some reaching 1.6 GPa. This makes it comparable to high-grade alloy steel in strength, yet it is lighter and more elastic. The complex protein arrangement allows it to absorb substantial energy before breaking.
Nacre, or mother-of-pearl, is known for its unique combination of strength and toughness. It consists of microscopic aragonite “bricks” layered and cemented by an organic “mortar.” This “brick-and-mortar” structure absorbs impacts and resists crack propagation by deforming and interlocking. Wet nacre can exhibit a tensile strength of around 140 MPa and a Young’s modulus of 70 GPa.
Bone and wood are natural composite materials where different components combine for enhanced strength and flexibility. Bone is a composite of hydroxyapatite (a hard mineral) and collagen (a flexible protein), creating a material that is both strong and tough. Wood’s cellular structure, reinforced by cellulose nanocrystals, contributes to its strength and resilience.
Engineered Materials: Human Ingenuity at Its Peak
Human innovation has created materials that push strength boundaries, often surpassing natural counterparts.
Graphene, a single layer of carbon atoms in a hexagonal lattice, is widely recognized as the strongest material ever tested. Its intrinsic tensile strength is an astounding 130 GPa, making it approximately 100 times stronger than steel by weight. This strength, combined with its one-atom thickness, gives graphene immense potential.
Carbon nanotubes (CNTs), rolled-up sheets of graphene, also exhibit remarkable strength-to-weight ratios. Individual single-walled CNTs have shown tensile strengths from 13 to 100 GPa, with multi-walled CNTs reaching 63 GPa. When assembled into fibers, CNT bundles exceed 80 GPa, though achieving theoretical strength in macroscopic forms remains a challenge.
Metallic glasses (BMGs) are alloys with an amorphous atomic structure, lacking the ordered pattern of conventional metals. This disordered arrangement provides exceptional properties, including very high yield strength and hardness, often exceeding crystalline metals. Some iron-based BMGs achieve yield strengths over 3.3 GPa, higher than any other metallic alloy.
High-performance ceramics, such as silicon carbide (SiC) and boron nitride (BN), are engineered for extreme environments due to their hardness and heat resistance. Silicon carbide provides high strength and hardness for wear resistance. Cubic boron nitride (c-BN) rivals diamond in hardness, used in cutting tools and abrasives. These ceramics maintain integrity at elevated temperatures.
Synthetic fibers like Kevlar and Dyneema are human-made materials with superior tensile strength, critical for protective gear and ropes. Kevlar, a para-aramid fiber, is five times stronger than steel by weight, used in bulletproof vests and helmets. Dyneema, an ultra-high molecular weight polyethylene (UHMWPE) fiber, is up to 15 times stronger than steel by weight. While Kevlar has slightly higher tensile strength (3.6 GPa vs. 3.2 GPa), Dyneema excels in abrasion resistance and floats on water.
Beyond Our Grasp: Theoretical Limits of Strength
While scientists develop robust materials, ultimate strength discussions extend into theoretical realms, considering concepts under extreme or hypothetical conditions.
One such concept is nuclear pasta, a theoretical state of matter in the crust of neutron stars. Simulations suggest it may be the strongest known material, requiring 10 billion times the force to break steel. This material is so dense, 100 trillion times the density of water, it could never exist on Earth.
Beyond materials, the strong nuclear force is a fundamental force binding atomic nuclei. It is the strongest of the four known fundamental forces, far surpassing others over subatomic distances. Though not a material, its power holds matter together, representing a foundational aspect of strength.
The notion of “unobtainium” also arises, a conceptual term for a material with ideal properties but practically impossible to obtain. Originating in aerospace engineering, it represents the ultimate hypothetical material, often appearing in science fiction. While a concept, it highlights humanity’s aspiration to create materials with greater strength.