I tend towards believing that there almost certainly is infinity existing, due to both the universe being flat and inflation having fairly good observational evidence.
So as far as the infinities I think likely exist, it is the type 1 multiverse due to flatness, and the type 2 multiverse, which is eternal inflation. And in eternal inflation, various universes have quantities that with the right tools can create infinities of what you want. The type 3 multiverse is essentially the many worlds interpretation of quantum mechanics, and I’d assign a 50-55% probability existing. The big type of multiverse that I don’t place much probability on existing is the mathematical multiverse/type 4 multiverse, aka all logically/mathematical universes exist. I’d only place a 1-5% probability on it existing.
May be there is some nuance needed. My perhaps out of date understating of physics is that:
The universe is expected to die a heat death so even if it goes on forever in some sense utility is finite, so at least from the point of view of infinite ethics nothing to worry about. Wikipedia describes this as the current leading theory here.
Quantum mechanics many worlds theories suggest the universe might be very very very very big but not infinite. (I don’t have a good source here.)
Physicists only use infinites in terms of limits, and as far as I know never use the kind of set theory infinites that come up in infinite ethics philosophy and have no basis in the real world as they are inherently paradoxical. See comment here.
I don’t know the types 1-4 of which you talk.
Either way even if you still don’t believe 1 − 3 above the main point I was making about even the possibility of the universe being finite remains sufficient.
I definitely agree that for the most part, we should probably stick to finite realms, because even if it is possible to get infinity, we have no plan of attack on how to do so, and the physics of our universe without changes only allows us finite utility.
The universe is expected to die a heat death so even if it goes on forever in some sense utility is finite, so at least from the point of view of infinite ethics nothing to worry about.
Even if that is the leading theory, we may be wrong. So I think we cannot rule out non-null utility being possible forever, and therefore there is a chance cumulative utility tending to infinity. However, I think there is an important distinction between something tending to infinity, and something being infinite. If utility tends to infinity, it is still finite at any given time, which means expected value calculations will not lead to unresolvable indeterminate forms.
Quantum mechanics many worlds theories suggest the universe might be very very very very big but not infinite.
Yes, in the sense that a physical theory can only suggest infinities as limits. There will never be data pointing towards infinities because these are not (physically) measurable.
I tend towards believing that there almost certainly is infinity existing, due to both the universe being flat and inflation having fairly good observational evidence.
I used to think along these lines, but I no longer think it makes sense to extrapolate this way. When I say a surface (e.g. of a table) is flat, I do not mean it is perfectly flat in a geometrical sense, just that its curvature is sufficiently small for me to call it flat in everyday language.
Similarly, when physicists claim the universe is flat, they just mean there is a very low likelihood that (the absolute value of) its curvature is higher than a very small value. However, that upper bound for the curvature is still infinitely larger than 0. In this sense we have zero evidence about the universe being exactly flat. The density parameter (see here) being Omega = 1 + VS = 1 + 10^-10^10^10^10^10^10^10^10^10 satisfies our data exactly as well as Omega = 1.
I tend towards believing that there almost certainly is infinity existing, due to both the universe being flat and inflation having fairly good observational evidence.
So as far as the infinities I think likely exist, it is the type 1 multiverse due to flatness, and the type 2 multiverse, which is eternal inflation. And in eternal inflation, various universes have quantities that with the right tools can create infinities of what you want. The type 3 multiverse is essentially the many worlds interpretation of quantum mechanics, and I’d assign a 50-55% probability existing. The big type of multiverse that I don’t place much probability on existing is the mathematical multiverse/type 4 multiverse, aka all logically/mathematical universes exist. I’d only place a 1-5% probability on it existing.
May be there is some nuance needed. My perhaps out of date understating of physics is that:
The universe is expected to die a heat death so even if it goes on forever in some sense utility is finite, so at least from the point of view of infinite ethics nothing to worry about. Wikipedia describes this as the current leading theory here.
Quantum mechanics many worlds theories suggest the universe might be very very very very big but not infinite. (I don’t have a good source here.)
Physicists only use infinites in terms of limits, and as far as I know never use the kind of set theory infinites that come up in infinite ethics philosophy and have no basis in the real world as they are inherently paradoxical. See comment here.
I don’t know the types 1-4 of which you talk.
Either way even if you still don’t believe 1 − 3 above the main point I was making about even the possibility of the universe being finite remains sufficient.
I definitely agree that for the most part, we should probably stick to finite realms, because even if it is possible to get infinity, we have no plan of attack on how to do so, and the physics of our universe without changes only allows us finite utility.
Thanks for clarifying.
Even if that is the leading theory, we may be wrong. So I think we cannot rule out non-null utility being possible forever, and therefore there is a chance cumulative utility tending to infinity. However, I think there is an important distinction between something tending to infinity, and something being infinite. If utility tends to infinity, it is still finite at any given time, which means expected value calculations will not lead to unresolvable indeterminate forms.
Yes, in the sense that a physical theory can only suggest infinities as limits. There will never be data pointing towards infinities because these are not (physically) measurable.
This is very much in agreement with Ellis 2018.
Hi Sharmake,
I used to think along these lines, but I no longer think it makes sense to extrapolate this way. When I say a surface (e.g. of a table) is flat, I do not mean it is perfectly flat in a geometrical sense, just that its curvature is sufficiently small for me to call it flat in everyday language.
Similarly, when physicists claim the universe is flat, they just mean there is a very low likelihood that (the absolute value of) its curvature is higher than a very small value. However, that upper bound for the curvature is still infinitely larger than 0. In this sense we have zero evidence about the universe being exactly flat. The density parameter (see here) being Omega = 1 + VS = 1 + 10^-10^10^10^10^10^10^10^10^10 satisfies our data exactly as well as Omega = 1.