Is this a Deterministic Universe

[Tanelorn]

I am not certain, but most here seem to be saying that we just don't know, one way or the other, if this Universe is truly random.

I think I am effectively asking whether, with a total understanding of all the Physics of the Universe, I can predict with absolute 100% certainty what I will have for breakfast ten years to the day from now, including the number of atoms of each element as well as the exact positions of all included subatomic particles at an instantaneous Planck point in time? And also if I will have indigestion afterwards :)

Everything I thought I knew said that this simple question can never be answered. I didn't realize that it was even something we weren't sure of.


Bill regarding Noether, doesn't this assume a Universe that is not going to change over time? Dark Energy may mean that it does change?

 

[audioloop]

I think I am effectively asking whether, with a total understanding of all the Physics of the Universe, I can predict with absolute 100% certainty what I will have for breakfast ten years to the day from now, including the number of atoms of each element as well as the exact positions of all included subatomic particles at an instantaneous Planck point in time? And also if I will have indigestion afterwards :)

Not 100 percent.

Maybe not, maybe you'll die tomorrow, nobody knows.

http://plato.stanford.edu/entries/probability-interpret/

http://www.princeton.edu/~achaney/tmve/wiki100k/docs/Probability_interpretations.html.

 

[Tanelorn]

Not 100 percent.

Maybe not, maybe you'll die tomorrow, nobody knows.

http://plato.stanford.edu/entries/probability-interpret/

http://www.princeton.edu/~achaney/tmve/wiki100k/docs/Probability_interpretations.html


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Exactly, so the universe is too random and complex to ever be able to calculate something like my above simple little breakfast question. Remember I meant someone with total knowledge and complete understanding of all the Physics in the Universe, as well as a computer the size of a planet.

Even creating another Universe and using it as a computer wouldn't work because each time would be different because of the same randomness argument.


Thanks, if every one agrees with you (and me) then I consider the question answered.


And so I am an accident, a lucky roll of the dice.. And no matter how many times the BB happens again (assuming a cyclical universe) none of us will be in them because they will all be different..

 

[audioloop]

perhaps the universe is completely predetermined from the "beginning"
predeterminism or is total chance indeterminism or half and half ?

Universe, etymologically: only one line (latin)
Predeterminism ?



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[Tanelorn]

My tired old brain can't work with these words, better to write down in sentences what you mean.

 

[audioloop]

Thanks, if every one agrees with you (and me) then I consider the question answered.


And so I am an accident, a lucky roll of the dice...

a nice roll...



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[audioloop]

My tired old brain can't work with these words, better to write down in sentences what you mean.

just pondering
totally random or totally determined...


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[bhobba]

I am not certain, but most here seem to be saying that we just don't know, one way or the other, if this Universe is truly random.

It goes further than that. So far all the theories we have are of the type that have deterministic or probabilistic interpretations. Because of that, in principle, it is unknowable.

I think I am effectively asking whether, with a total understanding of all the Physics of the Universe, I can predict with absolute 100% certainty what I will have for breakfast ten years to the day from now, including the number of atoms of each element as well as the exact positions of all included subatomic particles at an instantaneous Planck point in time?

As it stands you have asked a meaningless question because we do not know all the physics of the universe - we have zero idea what new laws that may be discovered will tell us.

But what we do know is this. The laws we do know have initial conditions depending on real numbers and any errors in the knowledge of those initial conditions tends to grow as time goes by so that predictions made without exact knowledge gets greater and greater until it becomes totally unreliable. This is the famous butterfly effect - since a real number requires infinite precision that is impossible to obtain, even if the universe is perfectly deterministic, its useless in practice - you can't predict just about anything with any kind of certainty.

Everything I thought I knew said that this simple question can never be answered. I didn't realize that it was even something we weren't sure of.

Yea - the universe is not only stranger than we imagine, it is stranger than most of us can imagine.

Bill regarding Noether, doesn't this assume a Universe that is not going to change over time? Dark Energy may mean that it does change?

It assumes the fundamental laws of nature, whatever they are (caveat given a bit later) are the same. Fundamental laws mean things like Maxwell's Equations, the laws of QM, Newtons Laws, Relativity and even future laws we may not know about. It's very hard to imagine a law that is not the same regardless of time, where you are, or what direction you are oriented in - its almost by the definition of law - its not really what you would call a law unless it's like that. So basically its really the requirement, more or less, that nature is describable by laws.

That this implies conservation laws like energy, momentum etc is - well shocking. Unless you have come across it before it would be the last thing you would have thought. Its a very very deep fact about nature:
https://www.amazon.com/dp/0918024161/?tag=pfamazon01-20
'Wigner points out that the basis for answering the question posed by him, 'Why is it possible to discover laws of nature?' is explained in every elementary physics text but the point is too subtle, is therefore lost on nearly every reader. The answer, he explains convincingly, lies in invariance principles. As an example, were local Galilean invariance not true it would have been impossible for Galileo to have discovered any law of motion at all. The same holds for local translational, rotational and time-translational invariance. Inherent in Wigner's argument is the explanation why the so-called principle of general covariance is not the foundation of general relativity, which also is grounded in the local invariance principles of special relativity.'

I strongly urge you if you are interested in actually understanding why the world is as it is, to get that book and study it closely.

Now for the caveat. Noethers theorem depends on the laws of nature being in a particular form called a least action principle. All the laws of nature so far known are like that and it would be a bit shocking if any was found that isn't, but it is an assumption.

Thanks
Bill

 

[Tanelorn]

Thanks Audio and thanks Bill. If the book you mention is mathematical I would likely not appreciate it. Advanced Math is like an alien foreign language to me unfortunately.

Thankfully the Universe knows what to do next after each Planck time slice even if it isn't aware of it.

 

[Naty1]

Thankfully the Universe know what to do next after each Planck time slice...

This is another wide ranging subject...search these forums for discussions of "time" if interested.

Note there is no consensus evidence time is discrete...nor continuous...and some suggest the question is meaningless! A minimum Planck time is but one way to consider time...one possible perspective. One model is continuous [relativity]; the other is discrete [quantum mechanics]...quantum gravity may be be neither


http://arxiv.org/abs/gr-qc/0604045
Unfinished revolution
Carlo Rovelli

...Roughly speaking, we learn from GR that spacetime is a dynamical field and we learn from QM that all dynamical fields are quantized. ... the conceptual foundations of classical GR are contradicted by QM and the conceptual foundation of conventional QFT are contradicted by GR: In conventional QM, time is treated as an external parameter and transition probabilities change in time. In GR there is no external time parameter… a notion of proper time is associated ….[with] each timelike worldline; yet in quantum theory there are no physical individual trajectories… only transition probabilities between observables….

...the physical variable measured by a clock is a nontrivial function of the gravitational field. Fundamental equations of quantum gravity might therefore not be written as evolution equations in an observable time variable. And in fact, in the quantum–gravity equation par excellence, the Wheeler-deWitt equation, there is
no time variable t at all...

 

[Tanelorn]

thanks Naty, well a Planck time slice is so thin that there is little difference between continuous and quantized in the macro world. It is probably is only important in the realm of QM.

 

[bhobba]

Advanced Math is like an alien foreign language to me unfortunately.

Unfortunately as far as UNDERSTANDING fundamental natural laws, and revealing its underlying beauty and simplicity math is necessary. If there is anything physics has shown us its that those laws are written in the language of math.

Two books at your level I would suggest are Feynman - The Character of Physical Law and Brian Cox E=MC^2 (I have that book as an audio-book because being a member of an audio-book club I get so many free as part of the membership and it really is surprisingly good - explaining many things including Noethers famous theorem)
https://www.amazon.com/dp/0679601279/?tag=pfamazon01-20
https://www.amazon.com/dp/0306818760/?tag=pfamazon01-20

You can also watch Feynman online:


Another excellent thing to read is Wigners famous essay:
http://www.dartmouth.edu/~matc/MathDrama/reading/Wigner.html

Thanks
Bill

 

[audioloop]

my farewell.

there are various "flavors" of determinism, or rather, degrees of determinism

Fatalism -> Predeterminism -> Adequate Determinism.

the high regularity of events in the world, assures that nature is not entirely indeterminate, ...at least.

dear tanelorn, your next breakfast is assured !

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[Tanelorn]

Thanks audio!

Bill one thing that would really help with maths like that is a companion. ie A full description in words of everything that each equation says and why it is being used. It wouldn't be hard yet mathematicians for some reason don't do it. Not everyone can or wants to learn this much math.

 

[MathematicalPhysicist]

I agree, every time you think you have found first cause you can always ask what caused that?
First cause and final effect therefore do not exist, just like a place at infinity cannot.

If there is no first cause nor last effect then we must deduce that causality is an illusion, or that there is a first cause which is also its last effect, we just haven't yet arrived at it.

Circle is the name of the game.

 

[Tanelorn]

If there is no first cause nor last effect then we must deduce that causality is an illusion, or that there is a first cause which is also its last effect, we just haven't yet arrived at it.

Circle is the name of the game.

MP, thanks for the reply!

Wait for it...

What caused this circle in the first place? lol