> Evidence implies something we can observe

That's an arbitrary definition. We can't observe our local past events or even non-local events, yet we use them as theories/evidence depending on context (eg Red Shifted galaxies as evidence of expansion). Reasoning about past events would affect other future events is just as much evidence. That's how physics experiments are generally conducted.

I can concede that there's not necessarily anything "outside" the spacetime bubble. The evidence of nothing is not the existing of something.

Then explain the Hubble volume: unless you believe the Earth is at the center of the universe, basic reasoning tells you that there is a sphere beyond which is outside our light cone, and yet outside which the universe still exists.

Are you saying the observable universe is bounded to our Hubble volume?

>basic reasoning tells you that there is a sphere beyond which is outside our light cone, and yet outside which the universe still exists.

Of course, but basic reasoning isn't evidence. Again... "evidence" implies something that can be observed, and something that can be observed, by definition, lies within the observable universe.

>Are you saying the observable universe is bounded to our Hubble volume?

I'm saying the observable universe is bounded to what we can observe, and evidence of something beyond the observable universe is a contradiction in terms.

I don't know how I can possibly make it simpler.

Wouldn’t that be interesting...

great sci fi plot, the earth is the center of the universe because anything out side of our sphere can’t be observed by our consciousness and ‘collapse’ into existence :)