# Really basic physics question

1. Mar 4, 2015

### yimmortal

ok, i know this is really basic, but if you don't ask then nobody can help. i'm trying to understand the basic way that math works with physics. for example, if i wanted to build a time machine, why would i need to use the math of physics? why would i need to solve math equations? wouldn't i realistically need someone that knew how to build things with a wrench?
i know that's a far out example, but i really don't understand how math can make things work like that???

or how would math help us to achieve a new method of space travel??

these are questions my son has asked me and i really don't have an answer for him... please take this seriously and answer in simple terms because my knowledge of science is quite limited

2. Mar 4, 2015

### ZapperZ

Staff Emeritus
You need math because you need to MODEL the system correctly. For example, your time machine will need to generate something to allow you to time travel. This something isn't easy to achieve (otherwise, we all have it already). So there must be some energy level that it needs to produce. How much that energy level is must be based on the physics, i.e. it requires such-and-such energy to split open the space-time continuum, and this requires extensive modeling using physics.

I will criticize you (and maybe your son, depending on how old he is) of trying to figure out the use of math using such an esoteric (and crackpottish) example. Why not figure out why you need math based on ordinary, regular material? Why would you need math to build your smart phone? Why would you need math to build the combustion engine in your vehicle? This would have been significantly more obvious, and illustrates clearly the use of math, rather than using a "time machine".

In the end, as I've written in my signature line, physics isn't just saying "What comes up, must come down." Physics must also say when and where it comes down. The latter requires math. It is the difference between simply providing a qualitative answer, versus a more rigorous and useful quantitative answer.

Zz.