I have an idea that I'd like your response to. Suppose

I think if a complete knowledge of the laws of nature and initial conditions of our universe could be used to predict the future then we would be living in a deterministic universe by definition which would be unchangeable by definition.

>>2412511
Well you haven't really addressed my question. Is it possible that I could choose to altar the future if I knew what the future was? Why or why not?

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Someone help me please god

>>2412599
i think it's safe to say by this point this girl's body is legendary, it gets posted so much

>>2412501
You are part of the universe too.
Your determination of all variables that influence the future would also contain the fact that you calculated it, it would have accounted for your physical body, your neural state, and your propensities, and your desire to change it.

>>2412501
>Suppose the future could be determined with the complete knowledge of the Laws of Nature and the knowledge of the initial conditions of our universe.
You couldn't do this within the bounds of the universe for a number of reasons. For example, you would have to be able to predict the behaviour of whatever you are using to predict the behaviour of the universe, etc. It's an impossible thing to do, so of course you get impossible situations arising out of it.

Ive thought this too anon, it depends if the future is definite, than there is no changing it, whatever you do the outcome will be the same. but if its not than i suppose you could change it

>>2412527
There are two possibilities.

Either A) the future has happened, making our existence determonistic and thus your changing of the future would already be calculated and not a change at all

Or B) the future has not occurred and this your ability to change it can't be confirmed as your ability to predict the future is flawed by changing it, ruining your prediction.

>>2412616
But this

>>2412608
>>2412616
>>2412626

I'm not seeing the criticism of "the calculated future would have accounted for your desire to change it", as a correct remedy.

The problem is my decision to change it is based upon the result of the future that is calculated.

If the future is calculable, then a correct calculation will produce a result.

I can, with the result, act purposefully to produce a different one.

How can a deterministic world account for that?

>>2412616
I don't see why this has to be true. Why could you not predict the behavior of the object used to predict the behavior of other things? Why could such an object not be able to predict the behavior of an object exactly like it, and then apply that to itself?

>>2412649
>I can, with the result, act purposefully to produce a different one.
No you can't.

>>2412649
"The problem is my decision to change it is based upon the result of the future that is calculated."

Is better said as, "The problem lies in the fact that the thing I will choose to do is the opposite of whatever the calculation says I will do. My action is based on the result of the calculation."

>>2412664
Then show why that is true. That is the nature of the problem. Saying I can't proves nothing.

>>2412672
Because you already accounted for every single atom in the universe, every neuron in your brain, every muscle fiber in your body, and extrapolated with perfect accuracy the exact displacement across some time t. That's what will happen.

>>2412649
>I'm not seeing the criticism of "the calculated future would have accounted for your desire to change it", as a correct remedy.
That's not what I'm saying. I'm saying that whatever mechanism you are using to perfectly model the behaviour of every single particle in the universe has to also be able to predict its own behaviour of modeling the future and so on in an infinite reucrsive loop, and such a computation would likely not be able to performed in the universe itself.

It's not that it predicted what you were going to do in light of your prediction, but that to make the prediction at all of every single particle is not possible.

>>2412677
You have not addressed the issue but restated what has been said. I understand what information the calculation would use to produce its result. It would account for every piece of information. The action I will take, however, is based on the calculation. Until the calculation is produced, it cannot be known what action I will take.

>>2412682
Sorry, I shouldn't have quoted you in that comment.

My response to you is here
>>2412657

>>2412657
>Why could such an object not be able to predict the behavior of an object exactly like it, and then apply that to itself?
The two objects mathematically cannot predict each other.
http://en.wikipedia.org/wiki/Laplace%27s_demon#Cantor_diagonalization

>>2412700
Thank you for the resource and I will try to understand the argument. Based on the information on Laplace's demon page I do not. Could you explain it?

>>2412683
>Until the calculation is produced, it cannot be known what action I will take.
If you could account for everything in the universe, then it CAN be known what you will do.

>>2412721
Well I'm not disagreeing. I'm saying it is impossible to produce a calculation when one of the necessary pieces of information needed for the calculation is what the result of the calculation will be.

That is the problem in mathematical terms.

>>2412732
>I'm saying it is impossible to produce a calculation
OP assumed it in the premise:
>Suppose the future could be determined with the complete knowledge of the Laws of Nature and the knowledge of the initial conditions of our universe.
So I am just holding him to consistency.

>>2412748
Okay, forget the supposed and think of our real, mutual existence. Could you refute the claim that the future is unknowable because of the problem I presented in
>>2412732
?

>>2412760
I dunno.

>>2412767
Crap, that is the question I should have originally stated in the OP but I misstated the idea I really wanted to have criticized.

>>2412719
Laplace's Demon is the traditional name of the particle-by-particle accurate predictor you're referring to in your OP. You could think of it like a demon or a machine or whatever happens to fit a particular analogy or hypothetical, but the relevant part is really the computation he/it/whatever is performing. So take the computations in isolation, and you can start making predictions abut what is and is not possible within the bounds of mathematics. It's pretty common in computer science, for example.

The theory used to disprove the possibility of the two machines predicting each other perfectly is in the references. To be perfectly honest with you, I only sort of understand it myself, but the gist of it and the implications are the important part.

>>2412776
Thank you, I understood what Laplace's Demon is, but not the proof about the two machines predicting each other. I'll tackle it if I'm feeling particularly self-loathing I suppose