What is the sharpest object in the world?

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If you were to ask someone what they think the sharpest object in the world is, the answer would probably be something along the lines of diamond or obsidian blades. But, while both obsidian and diamond can be used to cut through very hard materials, that answer would be wrong.

Yes, diamond and obsidian can be used to make very sharp blades. Diamond-based cutting tools are used in a variety of industries, and obsidian has been used ever since the Stone Age to make sharp tools. However, the sharpest object in the world uses neither of these materials – and its use might surprise you.

In this article, we are going to tell you all you need to know about the sharpest object in the world. But first…

sharpest object in the world

How do we measure sharpness?

First and foremost, we have to define how sharpness is measured. Sadly, there is no unit that measures sharpness itself. One of the reasons for that is that different objects can be considered sharp for some applications while somewhat blunt for others.

Knives and blades have their sharpness defined by their grind angle. This angle expresses the mechanical advantage of the wedge – in this case, the edge of the blade. The lower the angle, the sharper the blade.

However, a very sharp blade (one with a low angle) is also easier to deform or chip. A harder blade will deform with more difficulty than a softer one, yet that makes them more brittle and easier to chip. We can measure hardness using one of the many hardness scales, such as the Rockwell scale.

You don’t always want the sharpest object

But we don’t always want the sharpest object. In most cases, sharpness is relative – it all depends on the use case.

Objects with different applications can still be considered extremely sharp while not having the same mechanical properties. A razorblade, for example, is mechanically sharper than an axeblade (the razor has a lower grind angle), yet you wouldn’t use it to cut down a tree.

Sharpness is not the main factor when considering a cutting tool. We also have to factor in durability and how easy it is to use (and manufacture).

Are diamond or obsidian blades the sharpest objects in the world?

Sharpness and brittleness usually go hand in hand, which means that in practicality, you might not even want the sharpest blade you can find. You need something that will last through its intended usage, and you won’t need to sharpen after every cut.

Even though diamond and obsidian blades are not the sharpest objects in the world, they can get close. However, they also suffer from problems that make them unpractical in several scenarios.

The problem with diamond blades

Diamond is the hardest material we know. So, theoretically, that should mean you could use it to craft a very sharp and long-lasting blade, right? Well, not exactly. While very hard, diamond is also extremely brittle, and it has a tendency to cleave.

For example, if you could build a sword entirely out of diamond, it would probably shatter on your first blow against a metal object.

An alternative would be a metal sword with a diamond edge. This could be very sharp, albeit expensive – the metal would still chip away, taking the diamond with it.

Obsidian is also very sharp… and brittle

Obsidian is a naturally occurring glass used to craft pointy instruments since the Stone Age. This material is capable of being incredibly sharp – it could, at least in theory, fracture down to an individual atom – but it is very delicate.

Like diamond, obsidian is a very hard material, which means it is also extremely brittle. While great for sharp edges, obsidian is not very good for full-fledged blades. A small impact on an obsidian blade would likely shatter it.

sharpest object in the world - obsidian

The actual sharpest object in the world

Like we said, in theory, obsidian could be as sharp as the sharpest object in the world – because the sharpest object in the world is only one atom thick. However, besides having the same thickness, the sharpest object also has the added fact of being manmade.

Can you try to guess what the sharpest object in the world is?

Was your answer the nanotip of a scanning tunnel microscope? If so, you were exactly right.

The sharpest object in the world is the tip of a very expensive microscope. But what is it used for?

What is the sharpest object in the world used for?

But what exactly would someone need a one atom-thick needle for?

The tip of the needle needs to be very thin in order to be able to reach the atomic levels and image them. These tips are made from tungsten or a platinum alloy wire and require high-precision electrochemical etching or mechanical shearing processes.

With the depth these microscopes can reach, it is possible to image individual atoms. This would not be possible with a thicker needle tip.

Is it possible to make an even sharper object?

Objects are made of atoms, so it would be impossible to consider an object that was less than one atom thick. However, although they have never been observed, it is theorized that there can be even sharper “objects” in nature: cosmic cracks (or strings).

These strings are, theoretically, only one Planck length thick. As the Planck length is the smallest unit possible in the universe, these cracks would be the sharpest possible objects to naturally occur.

However, when it comes to real-life scenarios, the tip of the scanning tunnel microscope is the sharpest object in the entire world.