Fun with Newton's 1st Law and discrepencies within it.

[weinbergmath]

Hi Elgin,

A couple of things that might help clear things up:

Observing individual atoms is made possible by scanning electron microscopes which utilize principles of quantum mechanics to make the image. The principles of QM are important when looking at things that are so small, and Newtonian mechanics doesn't describe appropriately how things move at that scale. In fact, at this small scale, particles can tunnel through walls, and can have their properties changed simply by changing the container holding them. Take a look at this link to see an image developed at IBM showing what happens when a circle of atoms is small enough to contain an electron.

http://www.almaden.ibm.com/vis/stm/images/stm7.jpg

We can very easily appreciate Newton’s laws when looking at a robot stopping because it is a large object, and Newton’s laws are good enough to describe the objects we encounter in everyday life. When discussing atoms, however, we won’t necessarily observe a direct confirmation that the 1st law applies because quantum mechanics describes interactions on that scale, not Newton’s laws.

The other thing to remember is that in a gas, atoms/molecules are constantly bouncing off of each other, and so uniform motion does not generally occur except in the very brief periods between collisions.

Hope this helps at least a little bit!

Evan

[lukevanoort]

Newton's Laws and all other classical physics type stuff (si=v*t, si+v*t+a*t^2=sf, etc) are all approximations that work pretty well in everyday life, at everyday speeds. Classical physics doesn't really work well at very small scales, or at very high speeds. This is where quantum physics comes in, and, in addition to explaining some odd things, it makes really REALLY strange predictions and is just generally weird. If you ever feel like not only confusing yourself for one class, but instead for several weeks, look in to quantum physics, in particular topics like vacuum fluctuations and quantum coupling.