When we think about strength, we often think of sturdy materials like steel, concrete, or diamond. But what are truly the strongest substances and objects found on our planet? There are a few contenders for the title of “strongest object on earth” based on different metrics like tensile strength, hardness, and density. In this article, we’ll explore some of the most robust materials and constructs humans have discovered or created so far and what gives them their incredible durability.
Tensile Strength – Graphene Aerogel
If we’re talking about tensile strength, which measures the maximum stress a material can withstand before failing or breaking, graphene aerogel takes the top prize. This incredibly light material composed of graphene sheets and air is one of the lightest solids known, yet has a remarkable tensile strength of 3,000 kPa.
To put that into perspective, graphene aerogel can withstand over 300,000 times its own weight without deformation. It achieves this thanks to the graphene – atomically thin sheets of carbon arranged in a honeycomb lattice. Graphene itself is harder than diamond and hundreds of times stronger than steel, which gives the aerogel its superlative tensile strength despite being extremely porous and light.
Researchers are very interested in graphene aerogel for applications like high-performance composites, membranes, sensors, and electronics. Going forward, it has the potential to revolutionize materials science and engineering as more production techniques are developed.
Hardness – Diamond
When rating hardness, or resistance to deformation, scratching, and indentation, diamond is unmatched. On the Mohs scale of mineral hardness, diamond scores a perfect 10 out of 10, owing to the strong covalent bonds between its carbon atoms arranged in a cubic crystal structure.
The hardest natural diamond ever measured has a hardness of 167 GPa – no other gemstone comes close. The unique hardness of diamond makes it useful for industrial applications like cutting, drilling, grinding, and polishing. Diamond-tipped drill bits can penetrate the hardest rocks on earth.
Diamonds maintain their hardness at room temperature up to ~700°C. Above that, they begin transitioning into graphite, shedding their rigid crystal structure. So within normal environmental conditions, diamond’s properties make it the undisputed hardest material on earth.
Compressive Strength – Diamonds
Surprisingly, diamond takes the top spot again when it comes to compressive strength – the capacity to withstand loads tending to reduce size. Diamonds can handle pressures up to 60-70 GPa before shattering.
In comparison, most construction materials like concrete or granite fail at just 0.5 GPa. This tremendous compressive strength owes also to diamond’s tightly bound crystalline lattice that resists compression along any axis.
Diamonds form deep underground where they experience extreme pressure and temperature – explains why they excel at withstanding compression. This property combined with hardness makes diamond the ultimate material for industrial cutting and drilling, enabling diamond-coated tools to penetrate the most robust rocks and minerals on earth.
Impact Strength – Chromium
When considering impact strength, or how well a material resists high-speed impact like collisions or explosions, the metal chromium stands out. Chromium has an impact strength of 210 Megajoule per cubic meter (Mj/m3).
For perspective, cast iron scores around 50 Mj/m3, titanium alloys reach around 100 Mj/m3, and other high-impact metals like iridium or rhodium score under 160 Mj/m3.
Chromium achieves excellent impact resistance thanks to its body-centered cubic (BCC) crystalline structure. The uniform crystalline lattice enables chromium to deform uniformly rather than shatter on high-velocity impact.
Chromium’s combination of impact strength, hardness, and corrosion resistance make it highly valued for industrial applications like ball bearings, turbine blades, and auto parts. Going forward, chromium alloys may see wider use in impact-resistant components in aerospace or defense.
Heat Resistance – Tungsten
For heat resistance, tungsten takes the crown. This metal has the highest melting point of any element at 3,422°C – twice as hot as the melting point of steel or titanium.
In addition to an extremely high melting point, tungsten maintains excellent mechanical strength and creep resistance at high temperatures. While most materials become weaker when exposed to high heat, tungsten retains its durability up to ~1200°C.
These properties make tungsten invaluable for high-heat applications like light bulb filaments, rocket nozzles, and nuclear fusion reactor components. No other material can withstand the searing temperatures inside a fusion reactor like tungsten.
Going forward, tungsten will likely continue playing a critical role in next-gen nuclear plants and hypersonic vehicles that push material science to the limits.
Elasticity – Rubber
For elasticity, or the ability to deform under stress but return to the original shape, rubber reigns supreme. Natural rubber compounds can stretch up to 10 times their length and snap back perfectly at room temperature.
Rubber achieves this with long, coiled polymer chains that uncoil when stretched but quickly recoil when tension is released. No other solid material can match the elasticity of rubber-like polymers.
The elastic properties of rubber make it indispensable for tires, hoses, seals, shock absorption, and more. As polymers go, rubber sits in a class of its own when it comes to elasticity and resilience.
Toughness – Spider Silk
Considering toughness, or ability to absorb energy before failure, spider silk fibers excel. Spider silk rates 3-4 times tougher than Kevlar and about 10 times tougher than steel.
The dragline silk produced by orb weaver spiders to build webs can absorb massive kinetic energy thanks to long protein chains that unravel when impacted but immediately snap back together. This gives spider silk an unparalleled combination of high tensile strength and elasticity.
Research into mass-producing artificial spider silk hopes to enable next-gen applications in bulletproof vests, artificial tendons, airbags, and flexible electronics. Already scientists engineer proteins and polymers seeking to emulate the remarkable toughness of natural spider silk.
Density – Osmium and Iridium
For sheer density, the densest elements on earth are osmium and iridium. At room temperature, these precious metals used in alloys and electronics can achieve mind-blowing densities up to ~22,500 kg/m3.
To put that into perspective, that’s 15-20 times denser than lead, over 20 times denser than iron, and 200 times denser than water. A piece of osmium just 50 cm across would weigh over a ton!
The insane densities of osmium and iridium arise from their tightly packed crystalline lattice structures, with the highest atomic masses of any stable element. This gives osmium and iridium claim to being the densest materials found on our planet under normal conditions.
| Category | Strongest Material |
|---|---|
| Tensile Strength | Graphene Aerogel |
| Hardness | Diamond |
| Compressive Strength | Diamond |
| Impact Strength | Chromium |
| Heat Resistance | Tungsten |
| Elasticity | Rubber |
| Toughness | Spider Silk |
| Density | Osmium and Iridium |
Conclusion
After reviewing different metrics for strength, there are a few ultra-strong contenders that stand out as the toughest materials discovered or engineered on earth so far. Diamonds excel in hardness and compressive strength. Graphene aerogel is unparalleled in tensile strength and elasticity. Chromium leads in impact resistance, while tungsten can withstand the highest temperatures. Spider silk demonstrates unmatched toughness. And osmium and iridium take the crown for density.
Each of these super-strong substances derives its remarkable properties from the innate crystalline structure or molecular bonds of their elements or compounds. As materials science continues advancing, we may discover even stronger substances or develop new techniques to engineer them with precision. But for now, these exceptional materials represent the pinnacle of strength across their various categories – fully deserving the title of “strongest objects on earth”. Their unique capabilities make them essential across countless industrial and technological applications today.