do you believe in it? more importantly, if yes/no, what’s the reason why / why not?
i have had a great number of very enjoyable discussions with people about this topic. some say that it is unknowable what the eventual fate of the universe will be, because we can never have experimental confirmation that things will keep on moving forever, unless we wait for the end of the universe, which will never come (or at which point the knowledge would be useless).
however, i keep thinking that cosmic expansion will lift things out of a gravitational potential over time. i’m assuming that we’re all inside a big black hole (the whole universe is a black hole as an object with the mass of the entire observable universe just so happens to have a schwarzschild diameter of about the diameter of the entire observable universe). as the universe expands, its density decreases, therefore its schwarzschild radius decreases and we will eventually leave the black hole without doing anything for it; this obviously adds energy to the system.
or, in case cosmic expansion does not continue exponentially (but slows down over time), then the laws of physics would change over time; then, according to noether’s theorem, we could extract useful energy out of that change of laws over time. also black holes could grow to infinite size simply feeding on cosmic microwave background radiation continuously in this case¹. which we could use as an energy source.
[1]: do the differential equation, you get dM/dt ∝ M²·u₀/a(t) where M is the mass of the black hole, M² is proportional to the surface area, a(t) is the scale factor, and u₀ is the CMB density at current time. If a(t) is less than exponential, i.e. less than exp(Ht), then M(t) diverges in finite time for any black hole with big enough start mass.
sorry for such a verbose post :)
Physics happens right in front of us all the time. If you think it’s wrong, you need to show how in order to be believed; a lot of people have measured it and gotten the traditional results.
Heat death is about statistics, not gravity. A “typical” physical situation is a situation you can’t run a machine or a living organism on, basically. The universe started in a “weird” (low entropy) situation, but seems to be wandering back towards a typical (high entropy) one as things happen.
Black holes outlasting everything else is a different thing that might happen in the far future.
Not sure where you heard that. Cosmic expansion staying too small to really notice at normal scales, and physics running the same way as ever is a definite possibility.
BTW, in the future, you’ll get more nice, helpful replies if you frame it as “why doesn’t X alternate possibility happen?”. That’s usually a great question and an opportunity to learn, and it doesn’t disrespect anyone.