That's a very good and important historical question. You might be a
little disappointed at the answer: Nobody invented physics.
As
long as there were people, they wondered why things happened the way
they did, and what would happen if they tried other things. Well,
that's all that scientists do. You can imagine a caveman noticing that
fire is hot, and that rubbing two sticks together made them warm; he
might ask himself, "could I make fire by rubbing those stick together
really hard?" That caveman was being a physicist, and when he tried
rubbing sticks together, he was doing an experiment.
So
another way to answer your question is: Everyone invented physics.
Everyone who ever asked a question about why things happen is a
scientist.
Of course, over the years, there were many people
who made it their job to try to explain things, and some of them made
the biggest and most important discoveries in science. For instance,
you might've heard of the ancient Greek scientist Aritstotle, who tried
to explain the way things move. Another ancient Greek was Archimedes,
who invented and explained many simple machines, like levers and pumps.
Several hundred years ago, Galileo and Newton both discovered
important laws about gravity. In this century, probably the most famous
scientist was Albert Einstein; his "Theory of Relativity" talks about
all the strange things that happen when you're moving almost as fast as
light, and a lot of other cool stuff. (Einstein is one of my favorite
scientists, because he also did a lot of things besides science, like
trying to stop war.)
(published on 10/22/2007)