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What Is Spacetime, Really?

blog.stephenwolfram.com

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Re: What Is Spacetime, Really?

#31

Post by tux1968 »

codeulike wrote: post #30
tux1968 wrote: post #22

Things like this always leave me feeling stupid. How is one supposed to wrap their mind around the idea of space emerging from an underlying "network"? What exactly is being networked; what is the "stuff" of the network? He describes the network in terms of connections, which in my mind requires a topology, or space within which to exist; yet space does not apparently exist at this level. If there is no space, then w…

What is matter made of? The answer, whatever it is, cannot be matter. From what fundamental thing does 'space' arise? The answer, whatever it is, cannot be anything that would exist in a 'space' as such. And so we creep towards the idea that at a low enough level, everything is just information.

My confusion arises from his model of space emerging from something than in and of itself requires space to exist. It just seems circular.

And i don't see how the term "information" has much descriptive power when discussing nature at its most fundamental level. That may be a way to model it, or describe the physics of it, but that's just an abstraction of whatever that fundamental building block is.

Re: What Is Spacetime, Really?

#32

Post by api »

codingbinary wrote: post #24
api wrote: post #17

Earlier quoted context omitted.

Wolfram is known for this. He's clearly a bright fellow but he is not even close to being the only or the first person to work on stuff like cellular automata, computational theories of physics, or complexity. He did not invent everything he claims to have invented and while he does footnote he's definitely not drawing attention to any of the others in the area. It's tragic really. A New Kind of Science is full of br…

That is exactly the reason I stopped reading halfway through. I couldn't take any more of his narcissism.

I heard once that the book originally lacked many footnotes and they were added later after an outcry from the scientific community. I don't know if that's true but I can believe it.

Like I said the subject area is fascinating and merits a much warmer reception than this book got. Tragic.

Re: What Is Spacetime, Really?

#33

Post by grkvlt »

amelius wrote: post #14

Same topic, different approach: [1] [1] https://www.youtube.com/watch?v=W2XdhzCORbo

FYI - "The first lecture in a series given by Dr Peter Rowlands of the University of Liverpool on the Foundations of Physical Law. Further lectures will be uploaded after they have been given."

Re: What Is Spacetime, Really?

#34

Post by philipov »

tux1968 wrote: post #31
codeulike wrote: post #30

Earlier quoted context omitted.

What is matter made of? The answer, whatever it is, cannot be matter. From what fundamental thing does 'space' arise? The answer, whatever it is, cannot be anything that would exist in a 'space' as such. And so we creep towards the idea that at a low enough level, everything is just information.

My confusion arises from his model of space emerging from something than in and of itself requires space to exist. It just seems circular. And i don't see how the term "information" has much descriptive power when discussing nature at its most fundamental level. That may be a way to model it, or describe the physics of it, but that's just an abstraction of whatever that fundamental building block is.

It seems to me that the fundamental thing that Wolfram is saying is that reality is non-local. Locality itself is an emergent phenomenon. This is his clever way of getting around Bell's Theorem.

His networks don't require space to exist, they are space. When we think of spacetime, we think of a manifold, and he's saying that what looks like a manifold at a macro level is really just a discrete network at a micro level, and this sort of data structure is more suitable for explaining non-local phenomena, because locality is an effect, not a property, of the model. But for that to work, he has to derive all the current laws from his new model, and he is far from doing that, even though it is a quite fantastic thought experiment.

I think the confusion comes from the fact that at a fundamental level, we do not have the capability to know anything but models and abstractions derived from sense data, and no one is claiming their theories are more than models.

Re: What Is Spacetime, Really?

#35

Post by grkvlt »

redthrowaway wrote: post #4

I found this incredibly hard to read, due to Wolfram's constant need to self-aggrandize. The entire tone of the piece is, "I discovered this, then I discovered that". In reality, most of his "revelations" were discussed by others long before he arrived on set.

Agreed. Benoit Mandelbrot was the same; "When I discovered Fractals, which are a thing that I discovered, including the Mandelbrot Set, which is named after me, because I discovered it..." Wth some people it means I just stop listening to them, but I just ignore it here, since both Mandelbrot and Wolfram usually have interesting and insightful things to say as well.

Re: What Is Spacetime, Really?

#36

Post by j2kun »

If the answer is "there is such a program that reproduces the universe," then I have already found one such program that does it. Here it is: interleave the simulation of individual steps of every Turing machine in lexicographic order. That is, if the Turing machines are enumerated T_1, T_2, T_3, ... you do the following:

    i = 1
    while True:
        j = 1
        while j
If there is some program, it will be in the list.

This is the pitfall you get into when you only care about finding extremely short programs and don't think about efficiency. Similar pitfalls are in the philosophy of artificial intelligence. You get no useful information or theory or model if you ignore computational complexity.

Re: What Is Spacetime, Really?

#37

Post by tux1968 »

philipov wrote: post #34
tux1968 wrote: post #31

Earlier quoted context omitted.

My confusion arises from his model of space emerging from something than in and of itself requires space to exist. It just seems circular. And i don't see how the term "information" has much descriptive power when discussing nature at its most fundamental level. That may be a way to model it, or describe the physics of it, but that's just an abstraction of whatever that fundamental building block is.

It seems to me that the fundamental thing that Wolfram is saying is that reality is non-local. Locality itself is an emergent phenomenon. This is his clever way of getting around Bell's Theorem. His networks don't require space to exist, they are space. When we think of spacetime, we think of a manifold, and he's saying that what looks like a manifold at a macro level is really just a discrete network at a micro leve…

But a theory is supposed to model something that actually exists, yes? So for instance when philosophers made the conjecture for the existence of the atom, their theory was either correct or not, on the basis of whether the atom actually existed in nature.

So if Wolfram is correct, then there exists at the lowest level of nature a network, upon which everything else follows. Wolfram is trying to describe reality, something that exists, analogous to the existence of the atom? Do we agree this far?

If these Wolfram-nodes of our networked-reality do indeed exist, how are they connected in unique patterns if there is no "space" between them?

If his theory is not meant to predict something that actually exists, as in the prediction of the atom, well then, i'll bow out of this conversation because it's well and truly beyond my conception of what science is about.

Re: What Is Spacetime, Really?

#38

Post by MrQuincle »

amoruso wrote: post #16

If you want a second opinion, Cosma Shalizi reviews A New Kind of Science by Stephen Wolfram: http://bactra.org/reviews/wolfram/

Not so kind, but I loved to read that!! Thanks!

I'll definitely buy http://www.amazon.com/The-End-Science-Knowledge-Scientific/d... as well, the books he recommends w.r.t. Prigogine.

Re: What Is Spacetime, Really?

#39

Post by joekim »

amoruso wrote: post #16

If you want a second opinion, Cosma Shalizi reviews A New Kind of Science by Stephen Wolfram: http://bactra.org/reviews/wolfram/

Thanks for the link. I found the article to be very informative. Can't say the same thing about the original Wolfram article.

Re: What Is Spacetime, Really?

#40

Post by dragonwriter »

tux1968 wrote: post #37
philipov wrote: post #34

Earlier quoted context omitted.

It seems to me that the fundamental thing that Wolfram is saying is that reality is non-local. Locality itself is an emergent phenomenon. This is his clever way of getting around Bell's Theorem. His networks don't require space to exist, they are space. When we think of spacetime, we think of a manifold, and he's saying that what looks like a manifold at a macro level is really just a discrete network at a micro leve…

But a theory is supposed to model something that actually exists, yes? So for instance when philosophers made the conjecture for the existence of the atom, their theory was either correct or not, on the basis of whether the atom actually existed in nature. So if Wolfram is correct, then there exists at the lowest level of nature a network, upon which everything else follows. Wolfram is trying to describe reality, som…

> But a theory is supposed to model something that actually exists, yes?

Yes, but "model" is the key word. If it provides a set of rules which predict the way thing that exist in the world behave, then it models something (or set of things) that exits in the real world.

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