# Thread: Big Bang Singularity

1. Recently, I have read some "stuff" on the topic of singularities and Schwarzchild Radius and I noticed that many physicists theorise that the Big Bang was initially a gravitational singularity- which, by definition, means that the entire mass of the universe at this point was concentrated in a "sphere" of radius less than its Schwarzchild's Radius. So, this means that the escape speed from this "spherical singularity" would exceed the speed of light. Thus, my question is- how does this work, as I thought that general relativity tells us that the speed of light cannot be exceeded by anything carrying information? So any help with this question would be appreciated- and if I'm getting something completely wrong, then please correct me!

Thanks.  2.

3. This is correct but you need to remember that when we talk about an escape speed we talk about a force.
you have to do this difference between forces and velocity.
The most highest velocity is the speed light but the force is not limited.  4. The "big bang" insofar as it exists, is a singularity. That is, it is a place where the math of physics breaks down.

In the very, very early universe, the escape velocity, as you call it, is indeed greater than the speed of light. However, the scale factor of the universe was expanding at a great enough rate to ensure the density of the universe fell anyway, reducing this escape velocity.  5. Originally Posted by PhysBang
The "big bang" insofar as it exists, is a singularity. That is, it is a place where the math of physics breaks down.

In the very, very early universe, the escape velocity, as you call it, is indeed greater than the speed of light. However, the scale factor of the universe was expanding at a great enough rate to ensure the density of the universe fell anyway, reducing this escape velocity.
I dont think it connect to the fact that in a singularities condition the lows of the nature breaks down.
it just haven't any problem with this. it is not about carrying information be couse it just a force not a velocity.  6. Originally Posted by x(x-y)
Recently, I have read some "stuff" on the topic of singularities and Schwarzchild Radius and I noticed that many physicists theorise that the Big Bang was initially a gravitational singularity- which, by definition, means that the entire mass of the universe at this point was concentrated in a "sphere" of radius less than its Schwarzchild's Radius. So, this means that the escape speed from this "spherical singularity" would exceed the speed of light. Thus, my question is- how does this work, as I thought that general relativity tells us that the speed of light cannot be exceeded by anything carrying information? So any help with this question would be appreciated- and if I'm getting something completely wrong, then please correct me!

Thanks.
Singularities in GR are very subtle. A singulatity is not s apart of spacetime, despite the way that it is usually described.

Spacetime in GR is presented as a 4-dimensional abstract Lorentzian manifold, the geometry and topology of which are unknown, but are determined by the distribution of mass/energy which, via the Einstein field equations yields curvature which in turn determines the geometry and topology. So, the metric tensor of necessity is defined at every point in spacetime, and a singularity is not s spacetime point at which that tensor fails to exist.

Spacetime is, by definition, singular in a spacetime region in which it is impossible to extend timelike geodesics indefinitely far into the futute (as with black hole singularities) or indefinitely far into the past (as with the big bang singularity).

The Schwartzchild radius is not a singularity, though it can appear to be one in a local coordinate patch. This caused confusion for a long time until it was realized that the "singularity" was just an artifact of a coordinate system.

The only "sphere" of which I am aware, that even vaguely relates to what you describe, is the "trapped sphere"or " trapped null surface" of Penrose, which is associated with singular behavior of spacetime.  7. Originally Posted by Orionid
I dont think it connect to the fact that in a singularities condition the lows of the nature breaks down.
A singularity is, by definition, a place in a physical theory where the mathematics does not result in a meaningful physical description.
it just haven't any problem with this. it is not about carrying information be couse it just a force not a velocity.
Forces cannot be transmitted faster than the speed of light.  8. The universe began at that time as a big bang began the expansion. The big bang was the origin of space and time. It is tempting to think of the big bang as something like the explosion of an artillery shell. But it is more correctly an expansion of space itself, filled with hot radiation and matter. Scientists have been trying to visualize the creation of the universe implying properties cf energy and matter and by the experiments in nuclear reactors.  