An interesting implication of the multiverse theory is that it provides an answer for how we ended up with a universe with just the right combinations of gravity, electromagnetism, strong and weak nuclear forces. It's like the Goldilocks story -- tweak any of them to any other value and all matter would either repel into an nearly empty space or attract into one mass that would collapse under it's own density. There are other reasons for the multiverse theory, but under a theory of infinite multiverses, you would by definition create a universe where all the right combination of forces would come together to form our stars and planets -- including ones that can sustain life.
You're referring to the Anthropic principle[1] here, I believe? I tend to think this is not a very satisfying explanation, because it is not falsifiable[2]. More compelling/satisfying as an explanation to me, though controversial, is Lee Smolin's theory of cosmological natural selection[3], because though it may not be true, it at least makes some predictions that can be analyzed and modeled to study the correspondence to our universe, and so can be falsified or supported by improved accuracy and predictive utility of these models vs observations.
This is interesting. I had heard of this theory previously (Smolin), but didn't appreciate the Darwinian nature of it. You still get multiverses that each adopt their own distinct rules of physics, but natural selection plays in to how the universes are created. Some amount of information is transferred from the source universe to the one newly created, but the information is not lost -- something Susskin put forth some years ago by comparing the event horizon of a black hole to a hologram.
"it provides an answer for how we ended up with a universe with just the right combinations of gravity, electromagnetism, strong and weak nuclear forces."
No, we just ended up with a universe with the gravity, electromagnetism, nuclear forces that we know. That definitely doesn't make it "right." There could (should?) be an infinite combinations of those that would be "right" in other universes.
Right for sustaining life and that you and I are here and are having this discussion. This isn't a judgement of good or bad (though I'm glad to be here), just accounting for the the odds of arriving at our universe on chance alone. :)
I've always wondered about something similar: our universe (and our planet) is good for sustaining this specific type of life. But it doesn't mean there won't be any other type of life out there that could have been sustained with something different. Ie. it's possible that any type of universe would have produced life, and when lifeforms from different universes meet, they might not even recognize that it's life
That is a very interesting thought. out very definition of life hinges on the types of life we have seen. So its entirely possible that we may not even recognize other types of life
I also took your right to mean "right for sustaining life," and not as good or bad. However, as NhanH said very eloquently, we are only aware of "our" kind of life. Other lives may be very different, and may not depend on things that our lives do.
This is certainly possible. I should expand my definition as not only sustaining life, but rather avoiding two extremes: one scenario in which all matter repels from all other matter (on an infinite scale) and another in which all matter collapses on itself. These events would seem rather cataclysmic for our universe as a whole, but that could be chalked up to our limited understanding.
I can't help but think that in 200 years time this sort of meaningless and vapid introspection about the improbability of even existing will have thankfully gone the way of theology.
Said a different way, if you believe in the fine-tuned universe theory, then the multiverse theory would by definition predict our own outcome. It doesn't make either true, rather one of many puzzle pieces that happen to fit together. In 200 years, we may have proof of gravitational waves (or have found none) and many other interesting puzzle pieces that will continue to drive the thinking within quantum mechanics and string theory. Some believe the entire branch of string theory to be philosophy -- though I think this is limited by the belief that because we can't test many of these theories today that we will never find a way to test them in the future.
