Can we time travel like they do in the movies? The laws of physics might forbid it.
Albert Einstein's theory of special relativity explains how space and time are linked, but it doesn't include acceleration. By including acceleration, Einstein later developed the theory of general relativity, which explains how massive objects in the cosmos distort the fabric of space-time. The theory explains how this distortion is felt as the force of gravity, as it predicts how much the mass of an object curves space-time. Scientists test relativity by observing objects in space and seeing if their behaviors match up with Einstein's explanations of space-time and gravity, for instance by observing how light bends around massive objects as it travels towards Earth.
Our universe was born 13.7 billion years ago in a massive expansion that blew space up like a giant balloon.
A group of physicists has measured gravity using the effects of time dilation — the slowing of time imparted by increased velocity or gravitational force — on atoms.
Reference Albert Einstein's theory of general relativity is based on the idea that massive objects cause a distortion in space-time, which is felt as gravity.
Scientists tested seven different predictions, in one of the most ambitious and involved challenges to general relativity ever undertaken — and the theory passed with flying colors.
Einstein's paper on special relativity revolutionized light, light speed, matter and energy with a deceptively simple equation.
Once again, physicists have confirmed one of Albert Einstein's core ideas about gravity and relativity — this time with the help of a neutron star flashing across space.
Physicists dropped objects on a satellite for two years to test Galileo's theory of falling objects.
Warps in the fabric of space-time can act like magnifying glasses, and that may help solve a cosmic mystery about the rate of the universe's expansion, a new study found.
The three architects of supergravity are getting some high-profile recognition, more than four decades after they developed the influential theory.
Scientists created a computer simulation to test an alternative theory to the evolution of the cosmos.
While it's tough for humans and spaceships to travel near light speed, tiny particles do it all the time. Here are three ways that's possible.
One hundred years ago today, in the wake of the first World War, a British astronomer watched a solar eclipse for signs that a German physicist may have been right about warps in the universe.
A dancer gliding across a stage was so well synced with the projection around him that the performer appeared to trigger ripples coursing through the fabric of space-time.
The botched launch of two global-positioning satellites four years ago has proven to be a real gift to physicists.
Once again, a decades-old theory of gravity has survived a modern scientific onslaught. Einstein wins again.
The discovery of wobbling "hotspots" circling the drain of a massive black hole offers exciting new evidence for the behemoth that lies at our galaxy's center.