Isaac Newton’s law of universal gravitation is many things – revolutionary, elegant, mysterious – but, as it turns out, one thing we know for sure is that it’s not, well, universal. On the scale of our solar system, Newton’s observation – that objects attract one another with a force proportional to their mass and inversely proportional to the square of the distance between them – holds up. But, as with so many mathematical laws, when it comes to black holes, things break down.

The law also doesn’t work for the kinds of objects we interact with in our daily life, such as people, pencils and peanuts. This scale has proven extremely tricky to measure, and it gets even more imprecise at the scale of particles. This short animated explainer from MinutePhysics dissects the many things we know about gravitational force, and the many things we still have left to learn.

While there may be a category of objects at the extremes where Newton's law may not apply, currently the definition has been updated to state:

ReplyDeleteEvery point mass attracts every single other point mass by a force acting along the line intersecting both points. The force is proportional to the product of the two masses and inversely proportional to the square of the distance between them.