Every gravity calculation you will ever do shares one number. Measured in a basement lab in Texas or read from a star's orbit in another galaxy, the number agrees.
That number is G, the constant in Newton's law.
Written out, 6.67 × 10⁻¹¹ is 0.0000000000667, a tiny number.
G has the same value everywhere in the universe. The same G applies on Earth and in a distant galaxy. It is the same at every time and for every pair of objects, large or small.
An astronomy team models the orbits in a star system in another galaxy. Which value of G goes into the model?
Write down the fact:
G has the same value everywhere in the universe.
The star system sits in another galaxy, and everywhere includes it.
The team uses the same 6.67 × 10⁻¹¹ N·m²/kg² that applies on Earth.
A massive star makes a mighty gravitational force through its mass, m₁ in the law, never through a changed G.
Freya says the same value of G applies to a pebble on Earth and to a star in a distant galaxy. Is Freya correct?
Because G multiplies into every gravitational force, its tininess matters. The next lesson shows how much.
Which value belongs to the universal gravitational constant?
Which quantity has the value 6.67 × 10⁻¹¹ N·m²/kg²?
Two labs measure the universal gravitational constant: one in Texas, one on the Moon. How do their results compare?