Non-Newtonian curiosity

I love that they call this

I love that they call this “walking on water”. Technically, that is not a lie. Source: http://img.weburbanist.com/wp-content/uploads/2014/01/Walking-on-Water-Experiment-1.jpg

One of life’s mysteries: How can you run on a pool of Non-Newtonian fluid without asking how that is even possible?

Truth be told, I suspect that the question comes into people’s minds. Then they turn off their ears, when they hear the word “physics”. So let’s modify that question up there: How can you run on a pool of Non-Newtonian fluid, ask why it is possible and not want an answer more complicated than, “magic did it”?

Truth be told, I don’t think people really are like that.

If there is one thing I should highlight from my 20 years of teaching science it is this: Students – at any age – do appreciate not being lied to about things. So, here is how it goes:

  1. Physics is difficult and complex.
  2. Physicists use mathematics to make sense of this complexity.
  3. In order to master mathematics, and thus physics, you need experience.
  4. You need the interest and the patience to learn.
  5. Intelligence does not come into, as it were, the equation at all.

What does that mean with respect to Non-Newtonian fluids? Read this. Read it critically and see whether you have definitions for the following expressions which do not simply consist of replacing one expression with another equally abstract one.

Temperature, pressure, shear stress and viscosity.

That last one is interesting. The explanation given for it is simple enough. It is the “flow” or a measure for how easily a material in a liquid moves around. Now, read this.

Realise one thing: Viscosity, just like many other quantities in physics, is a name given to a variable in a term in a mathematical equation. It is an abstract quantity. If you think about it as a measure for how easily a liquid moves around you are missing something. You miss the fact that it can be applied to gases, for one thing, which seems a little weird. Most of all you miss, why it can be applied to gases and fluids if you do not understand the mathematics. And I have no way of really explaining it to you in any other way than through mathematics either.

So, do not ask me to explain something in easily understandable terms, at least do not if your goal is to obtain actual non-trivial knowledge. You will have to study. I had to as well; and bullet points 1-5 saw me all the way through.

And yes, it did get quite a little easier when I found out #5 was true, too. 😉


12108755_1507250599599792_3692866167745201820_nAlexander is a physicist, teacher and science communicator who is currently working at the Norwegian Centre for Space-related Education at Andøya Space Center in Norway. Even though, in his case, work and play do overlap, the content on this webpage is entirely private. You can follow Alexander on Twitter, Facebook and Google +

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s