Gravity what does it do

Albert Einstein discovered this principle. If you shine a flashlight upwards, the light will grow imperceptibly redder as gravity pulls it.

You can't see the change with your eyes, but scientists can measure it. Black holes pack so much mass into such a small volume that their gravity is strong enough to keep anything, even light, from escaping. Watch this video to find out more about these areas of immense gravity! Gravity is very important to us.

We could not live on Earth without it. The sun's gravity keeps Earth in orbit around it, keeping us at a comfortable distance to enjoy the sun's light and warmth. It holds down our atmosphere and the air we need to breathe.

Gravity is what holds our world together. Gravity is slightly stronger over places with more mass underground than over places with less mass. Areas in blue have slightly weaker gravity and areas in red have slightly stronger gravity. GRACE detects tiny changes in gravity over time. These changes have revealed important details about our planet. What Is Gravity?

What else does gravity do? And it goes beyond just our Solar System, as actually, every object that has mass in the Universe attracts every other object that has mass — again, all to varying degrees based on mass and distance. With his theory of relativity, Albert Einstein explained how gravity is more than just a force: it is a curvature in the space-time continuum. That sounds like something straight out of science fiction, but simply put, the mass of an object causes the space around it to essentially bend and curve.

It is similar to the way a coin would spiral down one of those penny slot cyclone machines you see at tourist shops, or the way bicycles spiral around a velodrome. We can also see the effects of gravity on light in a phenomenon called gravitational lensing. If an object in space is massive enough — such as a large galaxy or cluster of galaxies — it can cause an otherwise straight beam of light to curve around it, creating a lensing effect.

Besides being a characteristic of space, gravity is also a force but it is the weakest of the four forces , and it might be a particle, too. Some scientists have proposed particles called gravitons cause objects to be attracted to one another. But gravitons have never actually been observed. Another idea is that gravitational waves are generated when an object is accelerated by an external force, but these waves have never been directly detected, either.

Our understanding of gravity breaks down at both the very small and the very big: at the level of atoms and molecules, gravity just stops working. The problem is that our understanding of both particle physics and the geometry of gravity is incomplete. For centuries, physicists treated space as an empty framework against which events played out. It was absolute, unchanging and didn't — in any physical sense — really exist.

General relativity promoted space, and time as well, from a static backdrop to a substance somewhat akin to the air in a room. Einstein held that space and time together made up the fabric of the universe, and that this "spacetime" material could stretch, compress, twist and turn — dragging everything in it along for the ride.

Einstein suggested that the shape of spacetime is what gives rise to the force we experience as gravity. A concentration of mass or energy , such as the Earth or sun, bends space around it, like a rock bends the flow of a river.

When other objects move nearby, they follow the curvature of space, as a leaf might follow an eddy around the rock although this metaphor isn't perfect because, at least in the case of planets orbiting the sun, spacetime isn't "flowing". We see planets orbit and apples fall because they're following paths through the distorted shape of the universe. In everyday situations, those trajectories match the force Newton's law predicts.

Einstein's field equations of general relativity, a collection of formulas that illustrate how matter and energy warp spacetime, gained acceptance when they successfully predicted the changes in Mercury's orbit, as well as the bending of starlight around the sun during a solar eclipse. The modern description of gravity so accurately predicts how masses interact that it has become a guide for cosmic discoveries.

American astronomers Vera Rubin and Kent Ford noticed in the s that galaxies appear to rotate fast enough to spin off stars, like a dog shakes off water droplets. But because the galaxies they studied weren't whirling apart, something appeared to be helping them stick together.

Rubin and Ford's thorough observations provided strong evidence supporting Swiss astronomer Fritz Zwicky's earlier theory, proposed in the s, that some invisible variety of mass was speeding up galaxies in a nearby cluster. Most physicists now suspect this mysterious " dark matter " warps spacetime enough to keep galaxies and galaxy clusters intact.

Others, however, wonder if gravity itself might pull harder at galaxy-wide scales, in which case both Newton's and Einstein's equations would need adjustment.