# Lower limit to the distance between two mouths of a wormhole?

This is more like a conceptual question. Wormholes are tunnels connecting two different parts of the same universe or connecting two parts in different universes. Taking the former one as an example; It makes sense to think about them if the two mouths are spacelike separated since this way it makes the interstellar travel shorter.

According to Wikipedia (even though it's not a perfectly reliable source)

A wormhole could connect extremely long distances such as a billion light years or more, short distances such as a few meters, different universes, or different points in time.[2]

What happens if the mouths are so close to each other like a few $$mm$$ even $$nm$$ ? If they are too close, I can't think of a configuration where it would take shorter period of time to travel a distance through a wormhole than travelling between the points. (Unfortunately, we have covered Einstein-Rosen bridges superficially so I don't have the right machinery to carry out the math)

This way of thinking leads to a conclusion that there might be a lower limit to the distance between two mouths of an Einstein-Rosen bridge, I wonder what this limit is and how to find it, to be more precise is there even a lower limit?

Possible Way To Resolve This Dilemma

• Einstein-Rosen bridges don't necessarily make the travel time shorter between two points hence the distances shorter so it's reasonable to have as short distances as $$mm$$, $$nm$$ between the two mouths.

Yet I'm not sure of whether this assumption would be correct or not.

• If we're talking about classical GR, and you're making no specification about masses/energies involved, surely there's no associated length scale either? Mar 25, 2021 at 23:31