# Physics is Approximation

- (I can see a physicist having an aneurism at this title.)
- I actually buy that physics is entirely accurate.
- However, you can't take all forces into account.
- So, when you do a calculation of ball movement, you don't take
into account the gravitational force of the sun.
- Similarly, you don't know the actual friction of the air as
this varies.
- However, if you make simple assumptions (e.g. the
earth's gravity is the only important gravity for the
trajectory of a ball), the calculations are usually
reasonably simple.
- Do remember the tradeoff between accuracy and computational
efficiency.
- Approximations can be a lot easier to compute.
- A big question is when to include the actual physical law and
when to include an approximation.