1:05:04
What about the multiverse objection?
If there exists a vast multiverse, the probabilistic resources available to account for our finely tuned universe by chance are increased. Then, we could appeal to the Anthropic Principle.
Some cosmologists try to make the case that a multiverse actually exists.
Chaotic eternal inflation - popular universe generator. Assume for the sake of argument.
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1:10:12
Problem 1: Why such a large universe?
"... do we really need the whole observable universe, in order that sentient life can come about? This seems unlikely ... Let us be generous and ask that a region of radius one tenth of the ... observable universe must resemble the universe that we know, but we do not care about what happens outside that radius ... we can estimate how much more frequently the Creator comes across the smaller than the larger regions. The figure is no better than 10^10^123. You see what an incredible extravagance it was (in terms of probability) for the Creator to bother to produce this extra distant part of the universe, that we don't actually need .. for our existence."
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Roger Penrose
If we live in a multiverse generated by a process like chaotic inflation, then for every observer who observes a universe of our size there are 10^10^123 who observe a universe that is just 10 times smaller. That means if the universe really did arise from chaotic inflation, from just a quantum fluctuation of a vacuum, then the universe that we see beyond our region of space, say the nearest few hundred million light years, is not really there its an illusion, if you take this to the extreme ...
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[Shortly after 1:05:04]
Boltzmann Brains
"One argument that the universe had a beginning is that it hasn't reached thermal equilibrium or "heat death" yet. If the universe was infinite in age, it would have reached thermal equilibrium an infinity of time ago - so that is evidence of a beginning of time. Ludwig Boltzmann in the 19th century said the whole vast universe could be at thermal equilibrium except we only observe this tiny little patch. This patch is not in thermal equilibrium just by chance ... we have reached heat death but not in this tiny little patch. The bigger the patch is, the more improbable it is so the universe is much vaster than it needs to be to account for our existence. If you just have a solar system pop out of a statistical fluctuation its much more probable than to have this big vast universe pop out of a statistical fluctuation. Then if we see this big vast universe and just our solar system popped out of a statistical fluctuation, then it must be an illusion, The stars that we see are really not there, everything beyond the solar system is an illusion, you have to believe in illusionism so it was rejected."
1:11:31
"The Boltzmann argument is relevant to the multiverse argument today."
"Taken to the extreme we can have a universe pop out of a quantum fluctuation that contains one brain. Boltzmann's brains are by far the most common observers in the multiverse given their small size. The smaller the universe the more probable it is. Its far more probable for a Boltzmann's brain to occur in a multiverse than our vast fine-tuned universe with its long history. And so you're more likely to be a free floating brain than a person with a real history living in a 13.7 billion year old universe. The world we observe then is an illusion. You're the only person who actually exists. All your memories are false. The probability of forming our universe out of a quantum fluctuation at its present state with the appearance of age is more likely than forming it with its finely tuned initial conditions and its long history and so this is called the attack of the Boltzmann brains and its a real conundrum for the multiverse advocates. They basically have to give up realism and the whole world around them is an illusion if they want to believe in multiverse because the most common observer in the multiverse is a Boltzmann's brain."
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[Q&A 1:27:00]
If the multiverse theory is true then the most probable reality is that there is no fine-tuning, the universe arose as a quantum fluctuation consisting only of your brain, and everything else is an illusion. To believe in the multiverse is to believe in illusionism.
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1:12:50
Problem 2: The rejection of rationality
Anything that can happen, no matter how improbable, does happen countless many times in the multiverse.
Anything can be attributed just as readily to human design or to chance fluctuations of the quantum vacuum of the inflaton field.
Renders all scientific reasoning and explanations unreliable. Must believe in random miracles!
Multiverse cosmology can explain the origin of all events no matter how improbable, as long as they're not impossible, by reference to chance because of the infinite probabilistic resources it provides. Events we explain in terms of known causes based on ordinary experience are just as readily explained in multiverse cosmology as chance occurrences without any causal antecedent.
There is no way to attribute events to causal physical laws. All causes as seen to be related to effects really aren't. They're just chance fluctuations. Chance events. So you do away with the possibility of all scientific reasoning because scientific explanation and reasoning are unreliable. You must believe in random miracles. The scientific method is dead if you believe in the multiverse.