Brownian motion and how it causes problems for scientists.

Brownian motion causes no significant effects on macro structures such as humans. However, scientists are finding that it can cause problems when working at a nano-scale.

Does Brownian motion cause you any problems? Well, the answer is a resounding ‘no’! Brownian motion is the random movement of tiny particles by the bombardment of larger particles. You are a group of billions of particles and so, are far too large to notice this effect. The battle against forces like gravity, inertia and air resistance is more of a problem for you and other large structures.

However, if we were to shrink you down so you are the size of molecule, things would be very different. At this size and mass, gravity would hardly have any influence on you. However, the force of molecules bumping into you because of Brownian motion would! It would be like being hit from all sides by footballs travelling at great speed.

But the likelihood of you being shrunk is remote to say the least! So why is Brownian motion a real problem for scientists?

Nanotechnology

Nanotechnology is the study of tiny particles which are between 1 and 100 nanometres (nm) in size. These are extremely small particles, too small to be seen by a microscope. Nanoparticles have many uses – from suncreams to lightweight building materials – and scientists are looking to use them for many more applications in the future.

One such idea is to build nano-bots, which can enter a person’s body and deliver drugs or build new molecules in places where they are needed. However, one problem they would have to overcome is Brownian motion, which would cause the robots to be jostled around endlessly and may even cause them to break up completely. Does this problem spell the end for nanotechnology? Of course not! Inside your body, right now, your cells are building new molecules very successfully. If they can avoid the problems of Brownian motion then scientists can design nano-bots that can also avoid these problems – the next step is finding out how.

Further Work:

Your students can try out a simple experiment observing Brownian motion by trying the Homework Activity – Swirling colours and water molecules