Like Klaus said above me, I don’t really understand how the universe entering a contraction phase would smooth out and flatten its geometry – shouldn’t the curvature increase? Also, I’m not sure about black holes from previous “universes” (cycles) still existing – shouldn’t we observe some of their contributions (if not the black holes themselves) in the cosmic microwave background radiation? Furthermore, this needs some postulated scalar fields (like inflation does) with the additional assumption/property that dark energy will decay into a negative form of energy that will cause the universe to undergo a contraction phase. Not impossible, but a lot of assumptions, there.

I’d be happier to go with the Higgs metastable state/Higgs tunnelling as a potential explanation of a different kind of vacua in the future of the universe as a potential mechanism for crazy stuff to happen regarding its expansion (or maybe something like the Conformal Cyclic Cosmology that Roger Penrose is proposing).

I personally have a problem with eternal inflation in the fact that it might not be eternal after all. If I understand correctly the way stuff decays, on average stuff decays 50% after a half-time has passed. However, it could decay 30% or 99% or 100%, just by chance. And if this is true, then if you have eternity to wait, at some point all the inflationary material will decay everywhere in the multiverse, just by chance – it will just happen that 100% of the inflationary material will decay and the previously believed “eternal” inflation will stop. Am I making any mistake, here?

I don’t have a problem with this. If you literally have eternity to wait then it doesn’t matter how special the initial conditions are – maybe only patches of spacetime where these conditions are met undergo inflation, hence only these patches create a universe, and if the probability is non-zero, they will eventually happen – nobody is out there keeping a timesheet of when they happen. As easy as that.

You can create a virtual triangle using light from distant stars and see if its angle adds up to 180 degrees in order to determine the universe’s geometry (at least on that scale).

Luck does play a role but it depends on how frequent something that the experiment depends on happening actually happens. For example, it seems that substantial gravitational waves happen quite a bit, so they would have found them anyway. But it the situation was such that a detectable gravitational wave would happen every million years or so, then luck would play the most important role.

I would say that the things that will be forever out of reach are the ontological questions – what is energy, mass, consciousness, qualia etc. These questions cannot be answered by science even in principle.

Asta e interesant, suna corect.

Interesting. My problem is that if I imagine this future of simulating the infinite spectrum of computational universes then we have to ask “on which source of energy are the simulations going to run?”. Because if they need a source of energy, that is going to be limited by stars’ existence so… once the source of energy is gone, the simulation is also gone – they still depend on the physical world, they can’t escape the fact that the Universe is going to decay into deSitter space, thermal equillibrium. A depressing thought in the end.