in my life!
Einstein had landed inside a paradox. An object
that feels no force should travel at a constant
speed. But something accelerating because of
gravity feels no force. Einstein realized that if he
resolved the paradox, he might explain the origins
GENERAL RELATIVITY SPECIAL SECTION
Einstein labored for years
to explain mathematically
exactly how the
distribution of mass and
energy warps spacetime.
We have to stretch
out the time axis
nearer to the ground,
so the diagram curves.
Now a straight line
takes me from the
roof to the ground!
“It works roughly like this. Follow me
back to the roof. If we turn off gravity,
I just float—tracing a straight line in
“Now turn gravity back on. Earth’s mass
warps spacetime so that time on the ground
ticks slower than time on the roof.”
Einstein realized that Massive things like Earth
warp spacetime. A freefalling object then follows
the straightest possible path in spacetime. So—
even though that path doesn’t look straight to
us—the object experiences no force.
Today, Einstein’s general relativity remains scientists’
best understanding of gravity and a key to our
understanding of the cosmos on the grandest scale.