Respuesta :
Answer:
1) It governs the motion of planets around the sun, holds galaxies together and determines the structure of the universe.
2) Gravity is by far the weakest force we know. Gravity only attracts – there’s no negative version of the force to push things apart. And while gravity is powerful enough to hold galaxies together, it is so weak that you overcome it every day. If you pick up a book, you’re counteracting the force of gravity from all of Earth.
3) Gravity and weight are not the same thing. Astronauts on the space station float, and sometimes we lazily say they are in zero gravity. But that’s not true. The force of gravity on an astronaut is about 90 percent of the force they would experience on Earth. However, astronauts are weightless, since weight is the force the ground (or a chair or a bed or whatever) exerts back on them on Earth.
4) Explaining the microscopic behavior of gravity has thrown researchers for a loop. The other three fundamental forces of nature are described by quantum theories at the smallest of scales – specifically, the Standard Model. However, we still don’t have a fully working quantum theory of gravity, though researchers are trying.
5) Gravity might be carried by massless particles called gravitons. In the Standard Model, particles interact with each other via other force-carrying particles. For example, the photon is the carrier of the electromagnetic force. The hypothetical particles for quantum gravity are gravitons, and we have some ideas of how they should work from general relativity. Like photons, gravitons are likely massless. If they had mass, experiments should have seen something — but it doesn’t rule out a ridiculously tiny mass.
