The concept of the constant acceleration for different objects due to gravity (at the same height and ignoring atmospheric effects) is usually attributed to Galileo. In reality, Galileo merely popularized the concept with his Tower of Pisa Thought Experiment (What happens if you drop a cannon ball and a musket ball from the top of the Tower of Pisa?).

John Dee (Elizabethan England) was well aware of the concept and did not think it particularly note-worthy - implying it was a well known concept amongst his peers.

So who was the first person to discover this non-intuitive concept?

  • $\begingroup$ What do you mean by constant acceleration? Do you mean the fact that gravity accelerates different objects at the same rate (like a feather and a hammer), or are you referring to the fact that the acceleration due to gravity on a single falling object is constant all the way along the descent? $\endgroup$
    – Jack M
    Commented Oct 31, 2014 at 18:57
  • $\begingroup$ Different objects of different mass at the same rate $\endgroup$
    – winwaed
    Commented Oct 31, 2014 at 18:59
  • $\begingroup$ I've also updated the title and the text a little, in an attempt to clarify $\endgroup$
    – winwaed
    Commented Oct 31, 2014 at 21:18

1 Answer 1


From the comments, it seems you are really asking about the fact that (neglecting air friction) different objects fall with the same acceleration. Before the concept of acceleraton was fully understood, scholars would phrase this differently: different objects take the same time to fall a given distance.

John Philoponus, in the 6th century, is said to have performed the "Tower of Pisa" experiment (except not with that tower); the Stanford Encyclopedia of Philosophy has an extensive article on him, and the Wikipedia entry has this quote from his works:

But this [view of Aristotle] is completely erroneous, and our view may be completely corroborated by actual observation more effectively than by any sort of verbal argument. For if you let fall from the same height two weights, one many times heavier than the other you will see that the ratio of the times required for the motion does not depend [solely] on the weights, but that the difference in time is very small.

Marshall Clagett's The Science of Mechanics in the Middle Ages is a classic reference on this topic; it contains many original sources (in translation), with extensive discussion.

  • $\begingroup$ I've tried to clarify the question a bit.. Interesting references - I'm surprised I hadn't heard of Philoponus before, and it makes sense that Galileo referred to him a lot. $\endgroup$
    – winwaed
    Commented Oct 31, 2014 at 22:00

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