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 :)
I don't think being falsifiable is the most important part of a model. It's their ability to make accurate predictions about what happens in reality. All models are wrong. Some are useful, the saying goes.
Newtonian mechanics, which we know is wrong, can still be used accurately for a lot of near-earth orbital calculations. It got the Apollo missions to the moon.
It's my understanding that one of the most useful things about string theory is that it can make some really complicated or intractable problems much easier to solve within its frameworks. That's valuable, regardless of how truthful it is that everything is made of 11 dimensional strings.
The trouble with string theory is that plenty can be explained given its axioms and what comes out of the resulting math, but those axioms are completely unproven and unprovable and I haven’t seen anything come out of it that have turned into real world results.
String theory has made predictions that have turned into real world results. For example, it accurately predicted the properties of quark-gluon plasma. Sure, quantum chromodynamics can be used to make these predictions too but it's vastly more difficult.
That's why scientists keep working on it, because the value in a model is in its predictive power and a model's ability to make predictions elegantly is incredibly important for doing real world work.
The truth of the underlying perspective a model has on the universe is kind of secondary. Newtonian mechanics was wrong. Einstein's relativity was wrong. Quantum mechanics is, at the very least, incomplete. String theory most likely is wrong too. But they're still useful and valuable in the right contexts.