1094 6 MARCH 2015 • VOL 347 ISSUE 6226 sciencemag.org SCIENCE
For 100 years, the general theory of relativity has been a
pillar of modern physics. The basic idea is so elegant that
you don’t need superpowers to understand it.
Begin with Isaac Newton’s first law of motion: An object
remains in uniform motion unless acted on by a force. That
means if you feel no force you’ll either sit still or glide
forever in a straight line at a constant speed.
But albert einstein
asked himself ...
What happens if
I step off a roof?
While I’m freefalling
I feel weightless. I
don’t feel any force,
even as I accelerate
toward the ground!
STORY BY : ADRIAN CHO
ILLUSTRATION: NGUYEN NGUYEN