What Is the Weak Field Limit?

  • Thread starter Thread starter keepitmoving
  • Start date Start date
  • Tags Tags
    Field Limit Weak
AI Thread Summary
The weak field limit refers to scenarios where the gravitational field is small, typically observed at a distance from massive objects. Discussions highlight that extra dimensions might be perceived through the expansion of space, although this remains speculative. Differential geometry, which underpins General Relativity, shows that curvature can exist without invoking extra dimensions. The conversation emphasizes the importance of relying on testable phenomena to avoid misconceptions about the physical world. Ultimately, while there may be more beyond our experimental reach, scientific understanding should remain grounded in what can be observed and tested.
keepitmoving
Messages
97
Reaction score
0
what is the weak field limit?
 
Space news on Phys.org
keepitmoving said:
what is the weak field limit?
Generally, it's when the field in question is small. With gravity, for instance, the gravitational field is small when you're far away from any massive objects.
 
Chalnoth,
like i said, i`m just an amateur but couldn`t the extra dimensions actually be visible as the expansion of space and that they are staring us right in the face. Also, the actual physical world isn`t limited to what science can test for. thank you for your answer on the afield limit.
 
keepitmoving said:
Chalnoth,
like i said, i`m just an amateur but couldn`t the extra dimensions actually be visible as the expansion of space and that they are staring us right in the face.
Well, it is always possible to visualize curvature by considering a surface embedded in a larger-dimensional space. For instance, the surface of a sphere is a purely two-dimensional surface. We visualize the curvature of this surface, however, by looking at the surface in three dimensions.

One of the main insights of differential geometry (the mathematics behind General Relativity), however, is that you don't actually need to have extra dimensions to have curvature. The curvature in General Relativity (which is how the expansion is described: it's curvature in space-time) is fully depicted with no reference to any extra dimensions.

keepitmoving said:
Also, the actual physical world isn`t limited to what science can test for. thank you for your answer on the afield limit.
Er, but it is only stuff that we can test for, whether directly or indirectly, that we can be confident exists. The real world may well not be limited by our experimental abilities. And that's fine. But we had better limit ourselves to our experimental abilities lest we mislead ourselves.
 
thanks chalnoth but keep pushing that envelope out!
 
keepitmoving said:
thanks chalnoth but keep pushing that envelope out!
Naturally :)
 
https://en.wikipedia.org/wiki/Recombination_(cosmology) Was a matter density right after the decoupling low enough to consider the vacuum as the actual vacuum, and not the medium through which the light propagates with the speed lower than ##({\epsilon_0\mu_0})^{-1/2}##? I'm asking this in context of the calculation of the observable universe radius, where the time integral of the inverse of the scale factor is multiplied by the constant speed of light ##c##.
The formal paper is here. The Rutgers University news has published a story about an image being closely examined at their New Brunswick campus. Here is an excerpt: Computer modeling of the gravitational lens by Keeton and Eid showed that the four visible foreground galaxies causing the gravitational bending couldn’t explain the details of the five-image pattern. Only with the addition of a large, invisible mass, in this case, a dark matter halo, could the model match the observations...
Hi, I’m pretty new to cosmology and I’m trying to get my head around the Big Bang and the potential infinite extent of the universe as a whole. There’s lots of misleading info out there but this forum and a few others have helped me and I just wanted to check I have the right idea. The Big Bang was the creation of space and time. At this instant t=0 space was infinite in size but the scale factor was zero. I’m picturing it (hopefully correctly) like an excel spreadsheet with infinite...

Similar threads

Replies
0
Views
890
Replies
6
Views
2K
Replies
23
Views
3K
Replies
2
Views
1K
Replies
2
Views
1K
Replies
12
Views
3K
Back
Top