Why can masses curve spacetime?
952077
Its a general rule that things with mass will curve space time. This is through the theory of general relativity and universal gravitation. However, what we do not know is if gravity is responsible for frame dragging (where the mass actually twists space time) or just making a dent in it, or a combo of both. Additionally, many scientists are uncomfortable with relativity because it doesnt agree with quantum mechanics and the math is useless when applying it to black holes, both of which are equally real and can be proven. But why? Im afraid that that is a philosphical question that can be answered simply: they just do. And dont go there because that is a pandora's box, just keep things simple.
254919
Those would be changes that simultaneously affect time and space.  For example, if the mass of a black hole increases by swallowing a star, that would affect the curvature of space-time around the black hole.\n\nDoes that answer your question?  A few more details would help us to answer you better.
1103706
I have a suspicion that you are looking for a theological answer.  If this is the case then why ask the question in this scientific forum. On the other hand…\n\nIt takes all kind of mathematics to model the Universe. A lot of mathematical methods we are yet to discover. We prefer to mach methods of solution to a particular problem. Probability and statistic is used in business and also play a significant role in studies of subatomic particles such is Quantum Mechanics (QM) and QM is one of sciences that may look into origin of the Universe?  Almost at the same as QM a general theory of relativity (GTR) was introduced. The GTR uses tensor analysis and also is looking into the origin of the universe but on a very large scale. \n\nIn GTR we no longer can use Euclidean space.  Since you know that gravitation warps space and in warped space a straight line is no longer the shortest distance between two points. To model the space we have to substitute Riemann for a well known Euclidean geometry. \n\nI think every branch of mathematics, such as arithmetic, algebra, geometry, and calculus, contribute to a smaller or a larger extent by throwing some light on this question. String theory attempts to unite QM and GTR as an ultimate answer to the question into origin of the Universe.\n\nThe same knowledge is also used to compute the center of the Universe. One creates the model, substitutes known dimensions and computes the origin of the Universe. It is quiet simple, is it not? Actually it is not that easy since our knowledge expands and so is the Universe :).
503357
Maybe it's not really a mass generated force at all. It could just be that it is masses effect on space-time. Actually, I guess it could be that it's not the earth for example that causes gravity but space-times effort to put matter in clumps and roll it into a ball. The bigger the mass the more space-time there is to push against it. Einstein's example was to imagine a bowling ball sitting on a large rubber sheet. The bowling ball would deform the sheet and the curvature of the rubber represented gravity in space-time. The closer you get to the ball the more curvature you have. That would explain why gravity is weaker with added distance.
921042
If it has a strong gravitational field, light will bend towards it. No sucking involved.
229251
Your dad was right: space-time curvature is not something you can really understand outside from the mathematics framework of general relativity.\nHowever, the concept of the space bending can be intuitively pictured by a simple thought experiment: imagine we lived in a 2-dimensional world, that is, on a flat surface. This means we live completely within the surface, never escaping from it, maybe not even knowing that there are other dimensions. Then suppose this surface is bent due to some effect (gravity, in our case). If the bending is strong enough (if there is enough mass in the universe), the surface may be so curved to close on itself, for example forming a sphere.\nIn this imaginary scenario, you may build a spaceship and travel in a straight line from your viewpoint. But remember, you are traveling within the sphere surface. Seen from a 3D observer, your straight line is a circle. Therefore, in the end you will get at the starting point of the circle.
456899
because its the shortest path. light does not bend with gravity, spacetime bends with gravity, changing the shortest path.
452412
What Einstein developed in his General Theory of Relativity (published in 1915) was a totally new, mathematical description of gravity—one that linked space to time and mass to energy in a fundamentally geometrical fashion.  In other words, mass(-energy) shapes space(-time) instead of acting like a “force” in the traditional Newtownian sense.\n\nThus, in Newton’s description of gravity, one would say that all bodies exert an attractive gravitational force on one another.  In Einstein’s conception, one would say that all bodies change the underlying geometry of space (and time) in a way that causes them to be attracted to one another.\n\nWhat’s a little odd about this is that it’s a fundamental property of space(-time) in Einstein’s General Theory of Relativity that it is “warped” by the presence of mass(-energy).  So the answer to your question sounds a bit like an answer by fiat:  a gravitating body warps space because that’s what gravitating bodies do.\n\nThe caveat is that curvature or warping really only provides an analogy to what the equations tell us.  If you want to imagine the effects of an object on its surrouning space(-time), then you can think of it as changing the shape of space(-time) in its vicinity.  The distortion is real—we can measure its effects—but the images that are often presented (of flexible sheets of space-time with bowling balls or marbles rolling around on them) simply present analogous situations.\n\n\nRyan Wyatt\nRose Center for Earth & Space\nNew York, New York
527658
Ok for one anyone who has said light has mass is completely wrong. A black hole, as far as scientists know, is so massive that it infinitely distorts space time. Light is affected by space time. Think of it this way, you have sheet pulled tight then you drop a bowling ball on it but instead of just stretching it a finite amount, the divot in the sheet is infinite. Now if you were to roll a marble along the sheet it would go into that hole and not escape. Light is bent by the bends in space time so that when the light goes in it just follows the curvature of space time which "captures the light" and does not let it to flow back out.
268355
The geometry of the universe is non-euclidian. if you carry on going in a straight line you will eventually come back to your starting point.
736668
Unknown. Without an adequate theory of quantum gravity, this object that GR predicts would be a singularity cannot be described. At quantum mechanical scales, pure General Relativity is not a realistic depcition of space-time.
340102
I read all the answers and chewed over what ZAHIER had to say...as you know we are unable to leave earth to travel into deep space with out first using our gravity to gain speed and break away from our own gravity pull.... NO we cant at this time travel in a straight line into space, gravity will alter your course creating curves.
92597
Okay. Everything that has mass has gravity. You and I have our own innate gravity. So does your pencil, your computer, the air you breathe. \n\nIf you think of space-time (see Einstein) as the surface of a huge trampoline on which everything sits, then mass sits on top of that trampoline. But if you put a bowling ball on a trampoline, it puckers the surface and smaller things are drawn towards it, and it is drawn towards the smaller thing, if only a little bit. Similarly, if you roll a marble around the bowling ball, it will circle many times before it finally crashes into the bowling ball. (That how orbiting works.)\n\nThis is simplified, of course, but it helps to understand the concepts. If you are interested in the subject, I would recommend reading Billions and Billions by Carl Sagan.\n\nGood Luck!
1132078
gravity is the curvature of space-time.  The more mass an object has, the more gravity it has, the bigger the curvature.  Imagine a rubber sheet with a bowling ball on it.  The sheet is space-time and curves around the ball.  No energy necessary.
186113
There is no such thing as an aether. It is an old myth stemming from a misunderstanding among radio talk-shows.\n\nThere is also no such thing as mass-curvature, as it is not possible to describe as a dimension, and therefore have no curvature. If you are referring to the curvature in space that mass creates, then you have asked nothing.
126640
In general relativity, mass affects space and time, causing what we call gravity, and time dilation. The equations predicted that clocks in a gravity field would run more slowly, although the effect is very slight for most masses that we are familiar with, like the Earth. It has been measured and agrees well with predictions.\n\nSimilarly, the equations predicted that light would be bent around a mass, like the sun, and this has also been proved to be correct. In fact, strong gravity sources can create illusions, sometimes splitting the image of a light source behind a high-gravity object so it appears to us to be two separate images.\n\nA new discovery is that the rotation of a gravity source, like the sun or a galaxy, causes "frame dragging", that is, distorts spacetime like water around a spinning ball, also predicted by Einstein's theory.\n\nThere are a lot of good science sites on the web for this information.
646798
'Outside the universe' seem to me to belong to the universe!\nYou think the universe is that small???\nI do not know the answer on your question.\nLet me ask you: can the space time be curved without mass or only thanks to mass?