First, Will Kinney's tweet did not deserve such a thoughtful response. Kinney said "One of the reasons I don't believe in the Anthropic Principle is, that almost all of the universe is savagely deadly to warm little meatbags like us." This is a huge misunderstanding the anthropic principle, which does not require that most of the univers…
First, Will Kinney's tweet did not deserve such a thoughtful response. Kinney said "One of the reasons I don't believe in the Anthropic Principle is, that almost all of the universe is savagely deadly to warm little meatbags like us." This is a huge misunderstanding the anthropic principle, which does not require that most of the universe be hospitable for life. Even if only one observer comes into existence, the universe is sufficiently hospitable to be observed. The anthropic principle does NOT say this is the best possible universe for life. It only says that this is at least no worse than the worst possible universe for life. This may be the worst possible universe that can be observed.
Second, if every black hole is a universe, that is very bad news for us. Most black holes merge with other black holes. We have already seen some mergers, with LIGO. If our universe is inside a black hole inside another universe, the probability is that our black hole is orbiting another black hole and they will merge. What happens to a universe when it merges with another universe, with different physical parameters? I don't expect that is amenable to life, in either universe. Smolin's hypothesis does not explain why we happen to be in a universe whose black hole has not yet merged with another. Of course, observer selection would explain that, but then you don't need the rest of Smolin's hypothesis.
Third, this is not the best universe for making black holes. If the strange quark were a little lighter, more of our neutron stars would instead collapse into black holes. This is evidence against Smolin's hypothesis.
Fourth, all discussions of cyclic universes need to consider the nature of time. Smolin believes that time is real and fundamental, but (for example) Hawking believed time is emergent. If time is not fundamental, then there still might be an assembly of universes, but to say that one happened before another makes no sense. In short, the deeper question is whether time is inside or outside of the universe(s). If all the possible universes exist "at the same time" then understanding any interaction between them will require new physics. It may be that the ensemble of universes has a resonance pattern that favors universes that minimally support life. This is the "extremely-strong anthropic principle."
This is a great response Richard, packed with meaty points. I'm about to knock off the lights here in Berlin and go to sleep, but I will answer properly in the morning. I do have some thoughts on these issues.
I have to agree with the fourth point about time. If time is in fact part of the self-organizing or fine-tuning nature of the physics in every universe that gets created, then does the idea of evolution of countless versions, some of which will have look more like ours, fall apart? It seems to me at least conceivable that time is just another dimension that could be adjusted on the fly to maximize the conditions (lots of stellar black holes) needed to drive complexification, like Julian said.
First, Will Kinney's tweet did not deserve such a thoughtful response. Kinney said "One of the reasons I don't believe in the Anthropic Principle is, that almost all of the universe is savagely deadly to warm little meatbags like us." This is a huge misunderstanding the anthropic principle, which does not require that most of the universe be hospitable for life. Even if only one observer comes into existence, the universe is sufficiently hospitable to be observed. The anthropic principle does NOT say this is the best possible universe for life. It only says that this is at least no worse than the worst possible universe for life. This may be the worst possible universe that can be observed.
Second, if every black hole is a universe, that is very bad news for us. Most black holes merge with other black holes. We have already seen some mergers, with LIGO. If our universe is inside a black hole inside another universe, the probability is that our black hole is orbiting another black hole and they will merge. What happens to a universe when it merges with another universe, with different physical parameters? I don't expect that is amenable to life, in either universe. Smolin's hypothesis does not explain why we happen to be in a universe whose black hole has not yet merged with another. Of course, observer selection would explain that, but then you don't need the rest of Smolin's hypothesis.
Third, this is not the best universe for making black holes. If the strange quark were a little lighter, more of our neutron stars would instead collapse into black holes. This is evidence against Smolin's hypothesis.
Fourth, all discussions of cyclic universes need to consider the nature of time. Smolin believes that time is real and fundamental, but (for example) Hawking believed time is emergent. If time is not fundamental, then there still might be an assembly of universes, but to say that one happened before another makes no sense. In short, the deeper question is whether time is inside or outside of the universe(s). If all the possible universes exist "at the same time" then understanding any interaction between them will require new physics. It may be that the ensemble of universes has a resonance pattern that favors universes that minimally support life. This is the "extremely-strong anthropic principle."
This is a great response Richard, packed with meaty points. I'm about to knock off the lights here in Berlin and go to sleep, but I will answer properly in the morning. I do have some thoughts on these issues.
I have to agree with the fourth point about time. If time is in fact part of the self-organizing or fine-tuning nature of the physics in every universe that gets created, then does the idea of evolution of countless versions, some of which will have look more like ours, fall apart? It seems to me at least conceivable that time is just another dimension that could be adjusted on the fly to maximize the conditions (lots of stellar black holes) needed to drive complexification, like Julian said.