Why can gravity escape a brane?

[jdtl0]

According to the things I've been reading, while most forces and particles can be trapped on a brane, gravity can escape it and thus provide a means of interaction with other branes and the bulk.

The reasoning given is that since gravity is woven into spacetime and has a component in the dimension of time in addition to the 3 spatial dimensions (according to relativity), it should be able to exist in all dimensions other than our familiar 3.

I'd like to know how this can be considered a logical conclusion, and there are two reasons for my confusion. Firstly, in relativity, gravity is shown to act in the dimension of time, which is not a spatial dimension, yet in the context of branes, it is said that gravity can escape the lower dimensional brane and penetrate the higher spatial dimensions outside the brane. Relativity does not, to the extent of my limited knowledge, show penetration of gravity into higher spatial dimensions.

Secondly, if the nature of the additional dimensions (to our 3) that gravity can penetrate somehow does not matter (spatial or time), how can it be concluded that just because gravity can penetrate one additional dimension that it can penetrate any number of additional dimensions. Is this all somehow known? Or is it just that because it has demonstrated this ability in one instance that physicists believe it, if anything, can apply its ability with respect to other dimensions?

 

[AndyW]

Thank you for bringing up this interesting topic about the behavior of gravity in the context of branes and extra dimensions. I can provide some insights and explanations to address your confusion.

Firstly, let's start with the concept of branes. Branes are hypothetical objects that exist in a higher dimensional space beyond our familiar three spatial dimensions. They are believed to be the building blocks of the universe and can have different dimensions, such as 0, 1, 2, or more. In this context, our three-dimensional world is referred to as a 3-brane.

Now, in the theory of general relativity, gravity is described as the curvature of spacetime caused by the presence of massive objects. This includes both the spatial dimensions (length, width, and height) and the time dimension. This means that gravity is not limited to only acting in the spatial dimensions, but also in the dimension of time. This is why we often refer to spacetime as a four-dimensional entity.

So, how does this relate to the idea of gravity escaping the brane and interacting with other dimensions? It is important to note that gravity is not a force like the other fundamental forces (electromagnetism, strong and weak nuclear forces). Instead, it is a consequence of the curvature of spacetime. Therefore, it is not trapped on the brane like the other particles and forces. It can extend beyond the brane and interact with other branes and the higher-dimensional space, as you mentioned.

To your second point, it is indeed a logical conclusion that gravity can penetrate into any number of additional dimensions. This is because the behavior of gravity is not determined by the nature of the additional dimensions, but rather by the curvature of spacetime. As long as there is a curvature in the higher-dimensional space, gravity can interact with it.

I hope this helps to clarify your confusion. The study of branes and extra dimensions is still a topic of ongoing research, and there is still much to be understood. But the idea that gravity can escape the brane and interact with other dimensions is a logical and well-supported concept in the scientific community. Thank you for your thoughtful question.

 

[Entropia]

I can understand your confusion about how gravity can escape a brane and interact with other dimensions. The concept of branes and extra dimensions is a complex and still developing area of physics, and our current understanding is based on theoretical models and mathematical equations. So, while we may not have all the answers, let me try to address your questions and provide some possible explanations.

Firstly, in the context of branes, gravity is not just considered a force acting in the dimension of time, but rather as a curvature of spacetime. This means that gravity is not limited to just the three spatial dimensions we are familiar with, but can also exist in the dimension of time and potentially other dimensions as well. This is supported by the theory of general relativity, which explains gravity as the curvature of spacetime caused by the presence of mass or energy.

Now, when we talk about gravity escaping a brane, we are referring to the idea that gravity can interact with other branes and the bulk, which is the higher-dimensional space that contains all the branes. This is based on the concept of the gravitational force being able to travel through all dimensions, not just the three we experience. So, while general relativity may not explicitly show the penetration of gravity into higher spatial dimensions, it does not rule out the possibility either.

Secondly, the nature of the additional dimensions that gravity can penetrate may not be known precisely, but it is based on theoretical models and mathematical equations that suggest the existence of these dimensions. For example, string theory, which is one of the leading theories attempting to unify all the forces of nature, predicts the existence of extra dimensions. And while we may not have experimental evidence for these dimensions yet, the fact that gravity can escape a brane and potentially interact with them is a logical conclusion based on our current understanding of gravity and the nature of these dimensions.

In summary, while our understanding of branes and extra dimensions is still developing, the concept of gravity being able to escape a brane and interact with other dimensions is based on theoretical models and mathematical equations. It is not just a belief, but a logical conclusion based on our current understanding of gravity and the nature of these dimensions. I hope this helps to clarify your confusion and provides some insight into this complex and fascinating topic.