Discovery of Curved Space

Question 1

Newton’s Law of Universal Gravitation

Answer 1

Newton realised that all bodies in the
universe are attracted to each other
by a mysterious force - gravity

The same force that pulls apples to
the ground keeps the planets in orbit
around the Sun

This insight developed into Newton’s
Law of Universal Gravitation

Question 2

Newton’s laws of motion

Answer 2

An object remains at rest or continues to move at constant velocity, unless acted upon by an external force

The acceleration (a) of a body is directly proportional to the force (F) acting on the body and inversely proportional to the mass (m) of the body [𝐹 = 𝑚𝑎]

When one body exerts a force on a second body, the second body
simultaneously exerts a force equal in magnitude and opposite in
direction on the first body

Question 3

The Newtonian view of space

Answer 3

Believed space is an absolute, permanent
framework independent of matter

Space is a “stage” which matter played on

Matter moves about in space, but does not
affect the stage

Question 4

How can we tell if space is flat

Answer 4

Euclid - angles in a triangle always sum to 180o in flat space

Investigate whether this rule holds
true on Earth

If it doesn’t then space is not flat

Question 5

Einstein’s Spacetime Relativity

Answer 5

Einstein unified space and time into a 4-dimensional “spacetime”

Space and time are no longer absolute,
independent entities

Space shrinks (length contraction) and
time slow (time dilation) in response to each other

Question 6

The Einsteinian view of space

Answer 6

In his General Theory of Relativity (1915),
Einstein showed that spacetime is not
independent of matter

Spacetime is a real structure with elasticity and
shape

Matter changes the shape of spacetime

Spacetime is no longer a stage for matter to
play on, but rather an active performer

Question 7

Einstein’s Field Equation

Answer 7

This equation describes how the curvature of local
spacetime changes in the presence of mass (energy)

Matter tells spacetime how to curve, and spacetime
tells matter how to move

Question 8

Einstein’s view of gravitation

Answer 8

The equation describes how the curvature of
local spacetime changes in the presence of
mass (energy)

Gravity is a result of spacetime being curved by
matter