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Question

ok............check out these questions ya'll:

1. Before the seventeenth century, what ideas did people have concerning motion, velocity, and acceleration?

2. How did philosophers in ancient times explain motion in the solar system?

Answer 1

As mentioned, these questions often inquire about the European/Western Civilization view of science. That said, let's start with the Greek philosopher Aristotle.

Aristotle believed that nothing happened without a cause. While this is technically in agreement with Newton's laws of motion, Aristotle envisioned motion in a different way. He thought that a moving object had to be pushed, and once that push stopped, the object stopped. This differs from Newton's first law which says that an object in motion/at rest will stay that way.

Secondly, Aristotle believed that motion on Earth was different from motion in space. Specifically, he thought that objects on Earth preferred to move in straight lines, while those in space naturally preferred to move in curves. (More of his ideas, and the work done by Galileo and Newton to disprove these theories, are stated in the links below).

One of the earliest models of the universe (pre-Socratic times) is geocentric: the earth is the center of the universe and all other objects revolve around it. Though the telescope was not used until the 17th century, careful mapping of the sky showed that the motion of many objects in the sky cannot be modeled as simple orbits around the earth. Astronomers introduced epicycles in which planets moved around tiny orbits which in turn moved around the earth. (See link below for pictures.) The Ptolemaic model of the universe uses epicycles and a deferent to model motion.

This model was not quite right either, and in 1543, the heliocentric Copernican model was introduced. This is, more or less, the model we use to this day. However, not all people agreed with Copernicus, as they felt that various holy works (the Bible, Torah, etc) clearly indicated that the earth was the center of the universe. Tycho Brahe published his model, the Tychonic system, in the later 1500s. His model was mathematically (mostly) equivalent to the Copernican model, but left the earth in the center. Orthodox Jews, the Catholic church and others still use this system today.

Answer 2

Back in the old days the ideas about motion were that they were the will of god, remember that that was a time of change going from religious beliefs to scientific. They did understand motion and if you go further back you will find that the Aztecs, druids and Greeks had a good knowledge of motion and velocity and the solar system.

I have never liked questions like these you show for the simple fact that they are European based questions and they never take into account other cultures from other parts of the world. For question #1 they are basically asking about the period in Europe know as the "Renaissance" or the time of learning but really it was a time where christianity was first challenged by logic and science.

You instructor is probably looking for some specific answer from your text book.

Answer 3

Ans. to #2:-----I would guess that pre-judeocristian ideas would always stress or imply that gods were in activity in order for the
stars to move. In the Christian story of the moving star, this is actually put forth as the reason for this particular guiding star.
It was probably not until the 20th century that people actually began to think that God or gods were irrelevant to human and
world events. If I suggest that this is the core problem from
which all our problems stem, very few will be able to agree
with me. But eventually it will be obvious----obvious----that I
am right about that.