## Is time real in physics?

) and, like length, mass, and charge, is usually described as a fundamental quantity. Time can be combined mathematically with other physical quantities to derive other concepts such as motion, kinetic energy and time-dependent fields.

**Is it possible to travel backwards in time?**

As for backward time travel, it is possible to find solutions in general relativity that allow for it, such as a rotating black hole. Traveling to an arbitrary point in spacetime has very limited support in theoretical physics, and is usually connected only with quantum mechanics or wormholes.

**What comes out of a white hole?**

In general relativity, a white hole is a hypothetical region of spacetime and singularity which cannot be entered from the outside, although energy-matter, light and information can escape from it.

### How do you create a black hole?

To make a black hole, one must concentrate mass or energy sufficiently that the escape velocity from the region in which it is concentrated exceeds the speed of light.

**Can space be folded?**

For this reason, physicists think that travel great distances by “folding space” is highly unlikely to be possible. But suppose it were possible. There would be no limit to how far one could travel in space in almost an instant. Fortunately, such things are almost certainly not allowed by the laws of physics.

**Does fold mean times?**

As such, several dictionaries, including the Oxford English Dictionary and Merriam-Webster Dictionary, as well as Collins’s Dictionary of Mathematics, define “-fold” to mean “times”, as in “2-fold” = “2 times” = “double”.

#### What is the meaning of spacetime?

In physics, spacetime is any mathematical model which fuses the three dimensions of space and the one dimension of time into a single four-dimensional manifold. Spacetime diagrams can be used to visualize relativistic effects, such as why different observers perceive differently where and when events occur.

**Who discovered space-time?**

Albert Einstein

**Does gravity have kinetic energy?**

Gravitational energy or gravitational potential energy is the potential energy a massive object has in relation to another massive object due to gravity. It is the potential energy associated with the gravitational field, which is released (converted into kinetic energy) when the objects fall towards each other.