It is a bunch of nonsense to you and to Stephan Hawking and many others, but to many others (most?) it is not. No one knows who is right. The book tries to show a view where spirituality, 'leaps of faith' and indeed religion has a role in how we see the world. In my opinion it does an excellent job of delivering that message. As the tagline or whatever says, the book is not about making you believe in God, it's about making you want to believe in God. I don't take that statement litteraly, rather as a one liner describing the core message of the book.

As for your experiment, it makes me wonder if you understand what I am saying as it obviously would not give any answer to the philosophical question at hand.

No, it would not provide the answer. I was just annoyed at that moment. Sorry.

"Spirituality" is nonsense, and I don't see leaps of faith and religion presenting the real world, but a delusion, a deformed version of it.

I also not only do not believe in God, but I don't want to beleive in God either and would not be interested in serving God even if such a thing existed (for reasons I mentioned in other topics, and which I do not want to repeat).

Yeah, it's quite apparent that you don't buy into a world view that allows for anything 'supernatural'. Also I get that you (erronously in my opinion) feel that religion and spirituality promotes a dangerous world view. That's fine, the proposition of Life of Pi does not appeal to you, life goes on. However you feel about the book though, I still think it is a mistake to interpret it as a story that shows the danger of religious delusion. That is ironically 'missing the better story'.

Finally, and I know I should not ask this question because no good can come from it, but I ask anyway. Assuming that spirituality is nonsense, that the world can be described presisely using reason and physics, what makes it wrong to kill another man? If reality is nothing but physics and matter, how do you justify normative rules?

Nothing that exists is "supernatural". "Supernatural" is a term used to define things that people know nothing about, that's not part of their current bagage of world knowledge. Lot's of things were considered supernatural in the past (like giant squids), and are now viewed as perfectly natural. The book isn't a story that shows the dangers of religious dellusion, it's a book that UNWILLINGLY shows the dangers of religious delusion. It would've been a great story had there been no "unwillingly" part. The better story isn't always the "feel-good" one.

Normative rules are invented by people to make coexisting within a society possible. If people go around killing eachother, we might as well all be dead, as you can kiss progress goodbye. It's quite funny though that you ask this question. History shows that religion in no way stops people from killing eachother, or even makes it be percieved as something wrong. There are accounts in the Old Testament of Jews commiting genocide, and it being called a command from God. Things like the  Crusades or the Inquisition are also excamples. Heck, even this book is an example: Pi commits murder and cannibalism, yet he creates a fantasy story in which his terrible deeds never happened, so he can feel better about himself and never face any negative consiqunces for what he actions. He's religious/spirirtual beleifs didn't stop him from commiting attrocities. If anything, they helped him commit them.

You are skirting the issue or I am not framing the question clearly enough. In a world where there is nothing except physics and mechanics, why does a concept like 'progress' have any meaning? It doesn't make a difference to the atoms that make up a human if the human is alive or dead. What does gravity care about progress and coexsisiting within a society? In fact, by bringing up these justifications for norms you imply some form of 'supernatural' exsistence (perhaps "unwillingly"?). Why is progress and coexisting desirable and better than death and annihilation? In a mechanical world view there is nothing to place one as better than the other. You can't measure how 'good' something is using physics or math. (For reference, by supernatural I mean something that can't be observed and measured scientifically)

Also, this discussion really has nothing to do with religion even though you keep trying to bring this back to that topic. Religion is just an attempt by humans to frame these 'supernatural' concepts. That people have used it as a tool for thousands of years to divide, control, manipulate and murder other people is tragic, but not really relevant to the question. (Also, I think you'll find that in a world without any form of religion you would still have attrocities).

Finally, I don't think you are getting the full depth of the Life of Pi, and I am sure you feel the same about me. Let me just round out that part of the discussion by saying that I don't see Pi's actions as attrocious, rather quite heroic in all their grusomeness.

Now I fully get your question. My answer: Why not? I exist, I might as well make the best of it. If that's not good enough, you're free to kill yourself. And since I intend to be aroud 'till I naturally die, I aim to make my existence as pleasent as possible (and things like progress and coexisting make that possible). What "supernatural" existence am I "unwillingly" implying?

And since when is murdering someone and eating them a "heroic" act?

Surprisingly I first read this in Year 7 so did not fully understand it.

This answer does little to solve the puzzle. Fine, you aim to live a long life enhanced by progress and coexisting. What about the countless people who aim for detonating a nuclear bomb in a large city? What makes your choise 'good' and their choise 'bad'?

Without something that exsists outside of the mechanical universe there is nothing to judge the two different actions against each other. It's all just particles in motion anyway. The mechanical universe doesn't care one way or the other if I live and think or if I die and decompose. Basically, how does my desire to live carry more weight then someone elses desire for me to die? The right to life is not a law of nature. A purely mechanical universe have no normative rules what so ever. So without allowing for something that exsists outside of physical reality it's impossible to create a system of ethics  that is consistent.

It's important to note though that the fundament for normative rules doesn't have to be religion. It can be any number of things, but to my knowledge it can't be inferred from matter. If you know how that is basically what I started asking about. There has to be something outside of the physical representation of things that define what is good or bad. Be it that life has a value somehow in itself, or a rule made by a God somewhere or whatever.

And lastly, Pi survives for more than 220 days on a life raft in the pacific, with a homicidal madman that he eventually manages to kill. He stays alive by eating human flesh as a last resort. The killing of the crazed chef is completely justified both as a matter of self defense and as retribution for the chefs behavior, and eating human meat is also justifiable if it perserves your own life. To me Pi shows an unbendable will to survive which is heroic.

If we are all (or in the majority) in the belief that existence is good and preferable to non-existence, we can then enforce that norm, thus stopping the homicidal as part of a mutual pact to protect the lives that we generally agree that we love

Human life can be held sacred from a purely humanist and indeed nontheistic perspective, and imbued with meaning in our quest to make our own life and the lives of others better.

In a mechanical world, all our believes amount to nothing. They are just random collisions of atoms in a lump of fat. Also, the distinction between exsistence and non exsistence becomes meaningless since the matter exsists regardless of what happens to a human body. Remember, your soul or feelings doesn't really exsist in this world view, they are merely results of particles in motion. These particles will still move after death and destruction of the body.

point 2, I readily agree and also pointed that out in the post you are quoting. However, for us to hold up life as 'better' than non-life there has to be some sort of fixed point of morality or ethics if you will. My point is that this fixed point can not be found if exsistence is reduced to nothing but a deterministic mechanical view.