The accelerating expansion of the universe is usually explained by an invisible force known as dark energy. But a new study ...

Quantum theory and Einstein's theory of general relativity are two of the greatest successes in modern physics. Each works ...

All of the objects in our solar system are acted upon by forces. Forces are pushes or pulls. Every force has both a strength and a direction. Applying a force on something–like pushing a toy car–can ...

Legend has it that Isaac Newton had the moment of inspiration that would lead to his theory of gravity when, on a warm ...