# What is Space curvature: Definition and 22 Discussions

General relativity, also known as the general theory of relativity, is the geometric theory of gravitation published by Albert Einstein in 1915 and is the current description of gravitation in modern physics. General relativity generalizes special relativity and refines Newton's law of universal gravitation, providing a unified description of gravity as a geometric property of space and time or four-dimensional spacetime. In particular, the curvature of spacetime is directly related to the energy and momentum of whatever matter and radiation are present. The relation is specified by the Einstein field equations, a system of partial differential equations.
Some predictions of general relativity differ significantly from those of classical physics, especially concerning the passage of time, the geometry of space, the motion of bodies in free fall, and the propagation of light. Examples of such differences include gravitational time dilation, gravitational lensing, the gravitational redshift of light, the gravitational time delay and singularities/black holes. The predictions of general relativity in relation to classical physics have been confirmed in all observations and experiments to date. Although general relativity is not the only relativistic theory of gravity, it is the simplest theory that is consistent with experimental data. Unanswered questions remain, the most fundamental being how general relativity can be reconciled with the laws of quantum physics to produce a complete and self-consistent theory of quantum gravity; and how gravity can be unified with the three non-gravitational forces—strong, weak, and electromagnetic forces.
Einstein's theory has important astrophysical implications. For example, it implies the existence of black holes—regions of space in which space and time are distorted in such a way that nothing, not even light, can escape—as an end-state for massive stars. There is ample evidence that the intense radiation emitted by certain kinds of astronomical objects is due to black holes. For example, microquasars and active galactic nuclei result from the presence of stellar black holes and supermassive black holes, respectively. The bending of light by gravity can lead to the phenomenon of gravitational lensing, in which multiple images of the same distant astronomical object are visible in the sky. General relativity also predicts the existence of gravitational waves, which have since been observed directly by the physics collaboration LIGO. In addition, general relativity is the basis of current cosmological models of a consistently expanding universe.
Widely acknowledged as a theory of extraordinary beauty, general relativity has often been described as the most beautiful of all existing physical theories.

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1. ### I Approximate local flatness = Approximate local symmetries?

Pseudo-Riemannian manifolds (such as spacetime) are locally Minkowskian and this is very important for relativity since even in a highly curved spacetime, one could locally approximate the spacetime into a flat minkowski one. However, this would be an approximation. Perhaps this is a naive...
2. ### I Gravity: Compounded Space (Time) Signal?

Disclaimer - I am not an expert by any means so this might be as much about confirming my understanding as an inquiry from the general public... as such, it might be fairly conversational as I attempt to clearly communicate my thoughts and understanding. Please excuse this. If gravity is the...
3. ### I Why Do Objects Fall Along Spacetime Ripples?

When people try to explain how gravity works, the following example is constantly used . However, I don’t understand how this explains HOW gravity works. By using this example, gravity itself is used as a bias to explain how gravity works. How can explain gravity by saying “things fall along...
4. ### B Traveling using space curvature

Hi everyone. I'd like to verify my thoughts about travellig through space using a space curvature. Imagine you have a spaceship and you want to travel some distance. Your ship launches an object into space that has huge mass and density. It curves space. Now, you enter the curved space and...
5. ### I Is there a mechanism for creation of negative energy density

Excuse me for bad wording in the title, but there is only so much you can do with the character limit. So, has there ever been a proposal for a mechanism through which negative energy density could be created? Or the only possibility considered so far was that it would have been created in the...
6. ### B Space Curvature & Potential Energy

So I'm an Software Engineer, not a physicist, nor a mathematician. So I like to work in the qualitative, not the quantitative. Today I hit on a problem. I've been trying to remove the concept of "down" or "inward" from my thinking of gravity and GR. When people show the concept of space/time...
7. ### B Object interactions in relation to space curvature....

I'm a complete rookie in this field so please correct me where I go wrong, I just really want a better understanding of this subject. So as far as I am aware, mass causes the space surrounding it to curve or bend. What I want to know is how much does it bend the space? is the bending of space...
8. ### I Measuring Space Curvature w/ Swarzschild Coordinate System: Q&A

I have some questions about the curvature of space (NB not of spacetime) near a planet like Earth. Unambiguously defining space curvature requires choice of a coordinate system, so I choose the Swarzschild system. Here are my questions: Would constant-time hypersurfaces under the Swarzschild...
9. ### I 3D space curvature visualization

I want to program space curvature vizualizaion. I want to have an observer as a player that moves in 3d curved space and surrounding objects that will show curvature by distortion when player passes near them. I am concerned about some points: 1. What curvature to choose in order to experience...
10. ### Gravity Forces Us to Move: PF Forum

Dear PF Forum, I just want to ask a simple question. Even if we are at rest (ignoring that the Earth rotates, evolves around the sun, orbitting SMBH and Milky way orbitting what? Virgo Supercluster? And Virgo Supercluster to what?), A. So even if we are at "rest" (blue line), are we always...
11. ### Spacetime Curvature Difference: Gravity vs Speed

Gravity causes spacetime to warp. Relative speed also causes an apparent warp from the point of view of the stationary observer. But warp due to relative speed will cause rods to contract, rods will effectively measure shorter for the stationary observer. Accordingly we should also infer that...
12. ### Space Curvature: Friedmann Models Explained

Currently reading Peter Coles, Cosmology a very short introduction. There is a bit I don't understand. In a section discussing Friedmann Models, and how going on the cosmological principle density of the universe is the same in every place, and therefore space must be warped in the same way at...
13. ### The Arc of Space Curvature: Large and Small

When does the arc of the space curvature is large and when is it small?
14. ### Wouldn't The Time Being Relative Be A Product Of Space Curvature Near Mass

Now, I know that tittle is messy, so I'm going to explain it as clearly I can. One of the proofs to the fact that time is relative is, as I've heard. Putting one clock on the ground, and another a few feets above it. When these clocks measure time, the one above the ground will do it faster...
15. ### Gravity and space curvature confusion

Hello there. I'm new to the forums obviously. And I'm also quite new to physics. I've read many existing answers about how this works but I can't really understand how it would logically work out. From what I've understood. Gravity is not a force. Objects move in a straight line unaltered by...
16. ### Subatomic particle and space curvature

Can we say that each subatomic particle affects space time such that collectively as big as a planet it explains why there is gravity? Thank you very much.
17. ### Relation between graviton and space curvature

Hi, i read a few books (pop ones) and one thing that left me thoroughly confused was the relation between graviton and space curvature, is there any relation between the two... if we find a graviton then does it mean that space is not curved? regards Monty
18. ### Is space curvature misleading?

Yes, general relativity is out of my depths for now. Now I've often seen drawings of a gravitational source represented by a dimple ( downward ) on a surface. Yet GR never speaks of a fifth dimension. Nor have I ever seen a dimple upwards that I would suppose would represent repulsive gravity...
19. ### Scale Factor & Space Curvature

I will be writing my final exam tomorrow evening, and I am currently terribly stuck on the following practice problems. I have posted my thoughts below each problem. They look tricky to me. It would be very nice if someone could help me out and I will remain eternally grateful for your help...
20. ### What is the direction of space curvature around a mass in 3D space?

hi how is space curvature around a mass. i mean what's its direction in real 3D space? [ i know it is simillar to a rubber sheet with a ball on it, but it is 2 dimentional. i want its real demonstration. just like real world.]
21. ### Space curvature allows time travel to the past

Is it true that space can be curved around and loop itself to a point in the past? If this is true, then time travel to the future and the past should be theoreticly posible. I'm trying to further uderstand relativity, this is why I ask. If we could travel to the past, maybe we can really see...
22. ### Parallel lines and space curvature

ok, i know that this has in someway been answered before, and i am new here, i also am by far not a geometry major, but that is why i am asking here, because you peopl eknow this stuff. so here is the question the standard definition of parallel lines are two lines on the same plane that are...