Gravity is what kind of force

High Culture. The German thinker wrote both treatises and songs. He approached each form of expression with the same level of interest. Many have argued that free will is in illusion, but science does not support that. Albert Einstein described gravity as a curve in space that wraps around an object—such as a star or a planet.

If another object is nearby, it is pulled into the curve. Image credit: NASA. Anything that has mass also has gravity. Objects with more mass have more gravity.

Gravity also gets weaker with distance. So, the closer objects are to each other, the stronger their gravitational pull is. Earth's gravity comes from all its mass. All its mass makes a combined gravitational pull on all the mass in your body.

That's what gives you weight. And if you were on a planet with less mass than Earth, you would weigh less than you do here. You exert the same gravitational force on Earth that it does on you. Yet general relativity is remarkable in that it predicts its very own fall. General relativity yields the predictions of black holes and the Big Bang at the origin of our universe.

As one approaches the singularity at the center of a black hole, or the Big Bang singularity, the predictions inferred from general relativity stop providing the correct answers. A more fundamental, underlying description of space and time ought to take over.

If we uncover this new layer of physics, we may be able to achieve a new understanding of space and time themselves. If gravity were any other force of nature, we could hope to probe it more deeply by engineering experiments capable of reaching ever-greater energies and smaller distances. But gravity is no ordinary force. Try to push it into unveiling its secrets past a certain point, and the experimental apparatus itself will collapse into a black hole.

Daniel Harlow , a quantum gravity theorist at the Massachusetts Institute of Technology, is known for applying quantum information theory to the study of gravity and black holes:. Black holes can only be a consequence of gravity because gravity is the only force that is felt by all kinds of matter.

This constraint is not relevant in everyday situations, but it becomes essential if you try to construct an experiment to measure the quantum mechanical properties of gravity. Locality is important to the way we currently describe particles and their interactions because it preserves causal relationships: If the degrees of freedom here in Cambridge, Massachusetts, depended on the degrees of freedom in San Francisco, we may be able to use this dependence to achieve instantaneous communication between the two cities or even to send information backward in time, leading to possible violations of causality.

The hypothesis of locality has been tested very well in ordinary settings, and it may seem natural to assume that it extends to the very short distances that are relevant for quantum gravity these distances are small because gravity is so much weaker than the other forces. To confirm that locality persists at those distance scales, we need to build an apparatus capable of testing the independence of degrees of freedom separated by such small distances. Therefore, experiments confirming locality at this scale are not possible.

And quantum gravity therefore has no need to respect locality at such length scales. Indeed, our understanding of black holes so far suggests that any theory of quantum gravity should have substantially fewer degrees of freedom than we would expect based on experience with the other forces. Juan Maldacena , a quantum gravity theorist at the Institute for Advanced Study in Princeton, New Jersey, is best known for discovering a hologram-like relationship between gravity and quantum mechanics:.

Gravity is not just the attraction between objects and the Earth. It is an attraction that exists between all objects, everywhere in the universe.

Sir Isaac Newton -- discovered that a force is required to change the speed or direction of movement of an object. He also realized that the force called "gravity" must make an apple fall from a tree, or humans and animals live on the surface of our spinning planet without being flung off.

Furthermore, he deduced that gravity forces exist between all objects. Newton's "law" of gravity is a mathematical description of the way bodies are observed to attract one another, based on many scientific experiments and observations.