Perhaps what I’m really objecting to here is the idea of the Cosmological Horizon itself. Or perhaps I’m misunderstanding what the Cosmological Horizon is. My understanding of it is that the Cosmological Horizon is the distance from me that something would have to be so that I could never be effected by it again. If the Cosmological Horizon means something different than that, then maybe I don’t disagree at all.
I thought it might have been serving as placeholder for “past this distance it’s impossible to communicate or interact”. Technically, I don’t have a problem with the faster than light version, because then with enough time I would be able to interact with my daughter. But insofar as it’s a placeholder for “impossibly far away”, I have a problem with it.
… assuming a constant or accelerating inflation of the universe.
If the inflation of the universe slows down or stops, it won’t be the case anymore. And while it seems currently that the inflation is accelerating, we don’t know much about why it is doing so, nor if it’ll continue to accelerate or if it’ll slows down later on.
Even if the inflation stops or slows down, that’s still what “cosmological horizon” means.
This merely implies that if the inflation does stop or slow down, the cosmological horizon will also happen to coincide with “how far a signal could possibly travel until the complete death of the universe / the end of time”, for c-bound velocities. If there’s an upper bound on the spatial size of the universe, then the cosmological horizon might not exist in reality at this point. If there isn’t but it turns out we will never reach maximum entropy, then the cosmological horizon also doesn’t exist here.
Thanks. Then, if faster than light travel was possible, I wouldn’t be opposed to believing in things outside the Cosmological Horizon. Since that speed is impossible, I’m opposed to believing in things that leave here to go outside, or in things that were outside the entire time.
There is no way of knowing what things are like outside because we can never go outside and we have never been outside to observe, and we have no reason to believe that our current observations apply to the outside because there’s as much justification for the assumption that the outside is the same as the inside as there is for the assumption that the outside is fundamentally different.
(...) and we have no reason to believe that our current observations apply to the outside.
Not quite true.
Occam’s Razor says things are probably the same everywhere, whether inside or outside, which points towards our observations applying to the outside.
Since our observations apply to pretty much all of the inside, we should infer that they are also more likely to apply to pretty much any part of the outside because inference usually works with large samples (and the entire observable universe is something I’d consider a fairly large sample, if nothing within the observable universe goes against our current observations).
So we have two principles we could use to believe that our current observations apply to the outside. This requires that our priors for inference and Occam’s Razor working be set pretty high, obviously.
Perhaps what I’m really objecting to here is the idea of the Cosmological Horizon itself. Or perhaps I’m misunderstanding what the Cosmological Horizon is. My understanding of it is that the Cosmological Horizon is the distance from me that something would have to be so that I could never be effected by it again. If the Cosmological Horizon means something different than that, then maybe I don’t disagree at all.
The cosmological horizon is merely “Past this distance you have to go faster than light in order to send signals to eachother”
I thought it might have been serving as placeholder for “past this distance it’s impossible to communicate or interact”. Technically, I don’t have a problem with the faster than light version, because then with enough time I would be able to interact with my daughter. But insofar as it’s a placeholder for “impossibly far away”, I have a problem with it.
… assuming a constant or accelerating inflation of the universe.
If the inflation of the universe slows down or stops, it won’t be the case anymore. And while it seems currently that the inflation is accelerating, we don’t know much about why it is doing so, nor if it’ll continue to accelerate or if it’ll slows down later on.
Even if the inflation stops or slows down, that’s still what “cosmological horizon” means.
This merely implies that if the inflation does stop or slow down, the cosmological horizon will also happen to coincide with “how far a signal could possibly travel until the complete death of the universe / the end of time”, for c-bound velocities. If there’s an upper bound on the spatial size of the universe, then the cosmological horizon might not exist in reality at this point. If there isn’t but it turns out we will never reach maximum entropy, then the cosmological horizon also doesn’t exist here.
Fun stuff to think about, IMO.
Thanks. Then, if faster than light travel was possible, I wouldn’t be opposed to believing in things outside the Cosmological Horizon. Since that speed is impossible, I’m opposed to believing in things that leave here to go outside, or in things that were outside the entire time.
There is no way of knowing what things are like outside because we can never go outside and we have never been outside to observe, and we have no reason to believe that our current observations apply to the outside because there’s as much justification for the assumption that the outside is the same as the inside as there is for the assumption that the outside is fundamentally different.
Not quite true.
Occam’s Razor says things are probably the same everywhere, whether inside or outside, which points towards our observations applying to the outside.
Since our observations apply to pretty much all of the inside, we should infer that they are also more likely to apply to pretty much any part of the outside because inference usually works with large samples (and the entire observable universe is something I’d consider a fairly large sample, if nothing within the observable universe goes against our current observations).
So we have two principles we could use to believe that our current observations apply to the outside. This requires that our priors for inference and Occam’s Razor working be set pretty high, obviously.