Don’t know how you got the idea of infinite energy. Our universe has zero net energy. Too long of a discussion to go into so we leave it here.

Imagine you are living inside an opaque balloon. You can’t see outside but there are other balloons floating around. If any two balloons get pressed against each other then you can indirectly observe that from inside of your balloon.

Our universe is homogeneous all around in terms of distribution of matter and temp of the edge of the universe. Theory is that if another universe presses against the boundary of our universe then we should be able to observe that as an inconsistency (just like you can see indention of other balloon pressing against your balloon, even from inside). Scientists have found inconsistent regions of our universe where either the temp is below the average or there are no galaxies (great void). There is no direct proof that another universe is pressing against ours, but the point is that we probably can test the existence of another universe under some very specific conditions