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Of course you can. You just need to look at the number of possible states of the universe in order to make something possible. A universe with very simple rules

Of course you can. You just need to look at the number of possible states of the universe in order to make something possible. A universe with very simple rules doesn't need much to come about. A universe with complex rules is way less probable because it requires so many things to happen for it to start existing. Of course, there is a disclaimer: low probability doesn't mean that something is impossible. that's why we can only talk about what we expect, not rule out something as completely impossible.

ahelwer 6y ago
You are assuming a huge amount about how universes are generated, a process about which we know basically nothing.
- coliveira 6y ago
  Quite the opposite, I'm assuming very little. That's the whole idea of searching for simple universal laws.
  - tsimionescu 6y ago
    No, you are assuming that simpler things are more likely to appear out of nothing than complex things. There is no basis for this assumption outside the laws of physics themselves. In fact, in mathematics, the opposite is usually true - there are many more complex objects than simple ones, so given a random object, you should expect it to be complex rather than simple. For example, given a real number, it is infinitely more likely that it will be irrational rather than natural.
vbezhenar 6y ago
It is likely that our universe is a simulation [1][2]. And simulation rules could be absolutely arbitrary, including buggy Java program with thousands of edge cases. 1: https://www.scientificamerican.com/article/do-we-live-in-a-simulation-chances-are-about-50-50/ https://www.scientificamerican.com/article/do-we-live-in-a-s... 2: https://academic.oup.com/pq/article-abstract/53/211/243/1610975 https://academic.oup.com/pq/article-abstract/53/211/243/1610...
- tsimionescu 6y ago
  By the same arguments, there's a 50-50 chance that our universe is maya, illusion, and the only truth is one-ness. Or that it was created in the exact image of God, or whatever transcendental explanation you want to give. It would go like this: let's imagine that you were an omnipotent being. Then, one of three things must hold: either we will never become omnipotent beings, or omnipotent beings are not interested in creating a universe where creatures can become omnipotent beings, or we are living in the creation of an omnipotent being.
  - vbezhenar 6y ago
    We don't have any proofs that omnipotent beings are possible (and probably they are not possible, because university is considered finite). But it's obvious that simulating something is possible, as there are plenty of computer projects performing different simulations, so it's only a matter of scaling it up until something interesting will emerge. Even Conway's game of life is an interesting simulation with interesting creatures forming inside.
    - tsimionescu 6y ago
      There is no reason to expect that you could simulate the entire universe within the universe either; and even less reason to imagine it could be done losslessly, so that this could regress indefinitely, as the proof requires. In fact, I find that the idea that the universe could be entirely simulated in a portion of itself is actually very similar to the idea of omnipotent beings existing. They are about as plausible to me (not very) and have similar implications. In fact, if a human could run a simulation of the entire universe, they would be exactly equivalent to the idea of god for that universe, and could decide to enact whatever religious story they chose for their creations, including stuff like planting fossils that look millions of years old in a 6000 year old Earth, mutilating cows and causing crop circles, answering prayers for rain and floods, pulling the sun on a chariot across the sky etc. They could even decide to run beautiful simulations almost forever for people who do good after they die, and scary torturous simulations for those who did bad. So, if you believe in a simulation, you should also seriously consider that religious texts could be real and passed down from the runner of the simulation, whose name might as well be YHWH or Brahman.
tsimionescu 6y ago
You can't define the probability of universes existing on frequentist grounds (except for this universe, which has probability 1), and there are no reasonable priors to define this probability in Bayesian terms (and there would be no examples to help update your priors even if you did find reasonable ones), so the concept of 'probability of universes' is completely meaningless in a formal sense. It's like discussing the probability of the real numbers existing. To put it another way, a priori, without any predefined physical laws, anything is exactly as likely to exist. There's no reason, a priori, to say that a universe with an infinity of dimensions could not appear out of thin air, if you don't first postulate some physical laws. A universe where entropy always decreases is mathematically possible. If you lived in such a universe, your intuition may well be the reverse of ours - you may believe that more complex universes are more likely to appear than simpler ones, since objects with more states are more likely to appear out of thin air in such a universe.
- coliveira 6y ago
  That's incorrect. We are discussing here the set of possible models for the universe, not the necessary existence of multiple universes. In that case there is a clear set of candidates that we need to consider, making the probabilistic method meaningful.
  - tsimionescu 6y ago
    The set of possible models for the universe is infinite, and dominated by complex universes, as by definition there are fewer unique universes with fewer possible states than unique universes with more possible states.
    - coliveira 6y ago
      > possible models for the universe is infinite, and dominated by complex universes How can you even know this? Do you have at least ONE model for the universe? If that model is complex, how can you show that it works? I think you're just operating on figments of your imagination.

ahelwer 6y ago

You are assuming a huge amount about how universes are generated, a process about which we know basically nothing.

coliveira 6y ago
Quite the opposite, I'm assuming very little. That's the whole idea of searching for simple universal laws.
- tsimionescu 6y ago
  No, you are assuming that simpler things are more likely to appear out of nothing than complex things. There is no basis for this assumption outside the laws of physics themselves. In fact, in mathematics, the opposite is usually true - there are many more complex objects than simple ones, so given a random object, you should expect it to be complex rather than simple. For example, given a real number, it is infinitely more likely that it will be irrational rather than natural.

vbezhenar 6y ago

It is likely that our universe is a simulation [1][2]. And simulation rules could be absolutely arbitrary, including buggy Java program with thousands of edge cases. 1: https://www.scientificamerican.com/article/do-we-live-in-a-simulation-chances-are-about-50-50/ https://www.scientificamerican.com/article/do-we-live-in-a-s... 2: https://academic.oup.com/pq/article-abstract/53/211/243/1610975 https://academic.oup.com/pq/article-abstract/53/211/243/1610...

tsimionescu 6y ago
By the same arguments, there's a 50-50 chance that our universe is maya, illusion, and the only truth is one-ness. Or that it was created in the exact image of God, or whatever transcendental explanation you want to give. It would go like this: let's imagine that you were an omnipotent being. Then, one of three things must hold: either we will never become omnipotent beings, or omnipotent beings are not interested in creating a universe where creatures can become omnipotent beings, or we are living in the creation of an omnipotent being.
- vbezhenar 6y ago
  We don't have any proofs that omnipotent beings are possible (and probably they are not possible, because university is considered finite). But it's obvious that simulating something is possible, as there are plenty of computer projects performing different simulations, so it's only a matter of scaling it up until something interesting will emerge. Even Conway's game of life is an interesting simulation with interesting creatures forming inside.
  - tsimionescu 6y ago
    There is no reason to expect that you could simulate the entire universe within the universe either; and even less reason to imagine it could be done losslessly, so that this could regress indefinitely, as the proof requires. In fact, I find that the idea that the universe could be entirely simulated in a portion of itself is actually very similar to the idea of omnipotent beings existing. They are about as plausible to me (not very) and have similar implications. In fact, if a human could run a simulation of the entire universe, they would be exactly equivalent to the idea of god for that universe, and could decide to enact whatever religious story they chose for their creations, including stuff like planting fossils that look millions of years old in a 6000 year old Earth, mutilating cows and causing crop circles, answering prayers for rain and floods, pulling the sun on a chariot across the sky etc. They could even decide to run beautiful simulations almost forever for people who do good after they die, and scary torturous simulations for those who did bad. So, if you believe in a simulation, you should also seriously consider that religious texts could be real and passed down from the runner of the simulation, whose name might as well be YHWH or Brahman.

tsimionescu 6y ago

You can't define the probability of universes existing on frequentist grounds (except for this universe, which has probability 1), and there are no reasonable priors to define this probability in Bayesian terms (and there would be no examples to help update your priors even if you did find reasonable ones), so the concept of 'probability of universes' is completely meaningless in a formal sense. It's like discussing the probability of the real numbers existing. To put it another way, a priori, without any predefined physical laws, anything is exactly as likely to exist. There's no reason, a priori, to say that a universe with an infinity of dimensions could not appear out of thin air, if you don't first postulate some physical laws. A universe where entropy always decreases is mathematically possible. If you lived in such a universe, your intuition may well be the reverse of ours - you may believe that more complex universes are more likely to appear than simpler ones, since objects with more states are more likely to appear out of thin air in such a universe.

coliveira 6y ago
That's incorrect. We are discussing here the set of possible models for the universe, not the necessary existence of multiple universes. In that case there is a clear set of candidates that we need to consider, making the probabilistic method meaningful.
- tsimionescu 6y ago
  The set of possible models for the universe is infinite, and dominated by complex universes, as by definition there are fewer unique universes with fewer possible states than unique universes with more possible states.
  - coliveira 6y ago
    > possible models for the universe is infinite, and dominated by complex universes How can you even know this? Do you have at least ONE model for the universe? If that model is complex, how can you show that it works? I think you're just operating on figments of your imagination.