# Visualizing General Relativity with Fluid Analogy

• lukesfn
In summary, the author is interested in using a fluid analogy of general relativity to more easily visual what is going on in certain situations, without having to resort to visualizing curved 4d space time which is doesn't come to naturally. However, he doesn't know relativity quite well enough to understand what the nature of the fluid would be, or even if it is possible to specify a fluid type of metric that can replicate all the effects of GR.
lukesfn
I'm interested in using a fluid analogy of general relativity to more easily visual what is going on in certain situations, without having to resort to visualizing curved 4d space time which is doesn't come to naturally.

However, I don't know relativity quite well enough to understand what the nature of the fluid would be, or even if it is possible to specify a fluid type of metric that can replicate all the effects of GR.

GR is often introduced with the ball rolling on rubber sheet analogy, which I always found more confusing then helpful, because it is meant to show how curved space causes a ball to fall into a dip, but in that analogy, the force of gravity is what pulls the ball down the slope, so it doesn't actually help explain much. It isn't just space that is curved, it is space time.

Instead I have always imagined the idea of space flowing into objects. What I would now like to understand better is, what would be the nature of flow, and where does this analogy break down.

If one was to create an animation, in 2D, of an object, with space flowing into it, how would it look? I imagine that the density of space would change as gravity increases. I would imagine that such an animation would give a much more intuitive idea of what is happening in GR, although, I could imagine some people may not like it because it is suggestive of some time of redundant dynamic ether.

A.T. said:
Thanks a lot, I haven't found these before, but they look quite interesting after some speed reading. Looks like a good starting point. There is some mention of a fluid having a rotation at each point which sounds quite interesting.
A.T. said:
I think I have seen all of these links before. They are what I am trying to avoid. It's easier to imagine objects moving through a stream that is a similar shape to how we conceptualize the world a round us, rather then plotting some kind of geodesic on some strange higher dimensional space time surface it is difficult to relate to. Although, I expect that if you want to do any serious work, that is the way to go. Either way, it is good to be able to visualize things from different points of view.

## 1. What is the concept behind visualizing general relativity with fluid analogy?

The concept of visualizing general relativity with fluid analogy is to use the behavior of fluids to represent and explain the complex concepts of general relativity. This approach helps to make the abstract and often difficult-to-understand ideas of general relativity more tangible and easier to grasp.

## 2. How is fluid analogy used to explain the curvature of space-time?

Fluid analogy uses the behavior of fluids to illustrate the curvature of space-time caused by massive objects. In this analogy, the fluid represents the fabric of space-time, and the movement of objects through the fluid creates ripples or distortions, similar to how a rock dropped in a pond creates ripples on the surface.

## 3. Can fluid analogy also be used to explain time dilation?

Yes, fluid analogy can also be used to explain time dilation, which is one of the key principles of general relativity. In this analogy, the flow of fluid represents the flow of time, and the presence of massive objects can cause distortions in the fluid's flow, resulting in time dilation.

## 4. How does the fluid analogy help in understanding the concept of gravitational lensing?

The fluid analogy helps in understanding gravitational lensing by visualizing how the massive object (such as a galaxy or a black hole) bends the path of light, just as a lens would bend the path of light passing through it. This can be demonstrated by placing a small object (representing a source of light) in the fluid, and observing how its path is bent by the flow of the fluid around a larger object.

## 5. Are there any limitations to using fluid analogy for visualizing general relativity?

While fluid analogy can be a helpful tool in understanding general relativity, it is important to note that it is just an analogy and does not fully capture the complexities of the theory. It is also limited in its ability to explain more advanced concepts, such as gravitational waves. Therefore, it should be used as a supplement to other explanations and not as a substitute for understanding the full theory of general relativity.

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