Galileo

Galileo thought that if the frictional force could be reduced to zero
and a force applied to an object, it would continue to move forever.

Galileo thought that if the frictional force could be reduced to zero
and a force applied to an object, it would continue to move forever.

From this Galileo formulated _his_ Law of Inertia:

An object in a state of motion possesses an inertia causing it to
remain in a state of motion unless acted on by an external force.

Galileo brought...

Galileo thought that if the frictional force could be reduced to zero
and a force applied to an object, it would continue to move forever.

From this Galileo formulated his Law of Inertia:

An object in a state of motion possesses an inertia causing it to
remain in a state of motion unless acted on by an external force.

Galileo brought together his work on falling bodies and inertia and
stated that if a body is subject to two influences, each producing a
characteristic type of motion, the object will respond to each,
without affecting its response to the other.

If he could have imagined cannons firing projectiles great distances;
at escape velocity, then he might have seen that his inertial
component is not straight, but is elliptical, and his gravitational
component is not vertically straight, but bends back involutely;
continuously remaining perpendicular to the elliptical path;
centripetally directed toward the geometric center of the ellipse.

That's the way orbital motion works: The inertial component is curved
elliptically; not parabolically, and the centripetal component is not
straight, but curved involutely. If no external force - like friction
- is encountered an orbiting object; body or mass of matter will
continue to orbit forever; but that's only in theory; in actual
practice, nothing's forever.