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Reality doesn’t exist until it is measured, quantum experiment finds

anu.edu.au

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Re: Reality doesn’t exist until it is measured, quantum experiment finds

#161

Post by Strilanc »

The linked article is titled "Experiment confirms quantum theory weirdness". Please don't exaggerate the title. These experiments do not show that "reality doesn't exist until it's measured".

First, "realism" [1] is not the same thing as "reality". "Realism" basically means "physical quantities have a definite value". "Reality" is that thing that determines your experimental outcomes. Don't mix them up.

Second, interpretations of quantum mechanics disagree wildly about what kind of weird you use to explain things. Some interpretations have "realism", some don't. Some interpretations have retrocausality, some don't. Some interpretations have FTL effects, some don't. Since all the interpretations give (mostly) the same experimental predictions, it's misleading to single one out and say just that particular brand of weirdness was confirmed.

We confirmed that there's weird there. We didn't distinguish what brand of weird it is. Physicists widely disagree about which brand of weird to use, with no position achieving even a majority [2]. The original title was better.

1: https://en.wikipedia.org/wiki/Na%C3%AFve_realism#Realism_and...

2: http://www.preposterousuniverse.com/blog/2013/01/17/the-most...

Re: Reality doesn’t exist until it is measured, quantum experiment finds

#162

Post by yummyfajitas »

Strilanc wrote: post #161

The linked article is titled "Experiment confirms quantum theory weirdness". Please don't exaggerate the title. These experiments do not show that "reality doesn't exist until it's measured". First, "realism" [1] is not the same thing as "reality". "Realism" basically means "physical quantities have a definite value". "Reality" is that thing that determines your experimental outcomes. Don't mix them up. Second, inter…

I don't think the title is a misrepresentation of the article, just the physics:

From the article: "It proves that measurement is everything. At the quantum level, reality does not exist if you are not looking at it..."

The article does appear to be (incorrectly) arguing that this experiment proves one interpretation of QM correct. It's definitely incorrect - some years back myself and others used non-experimentalist interpretations of QM to get the same result - but it's not a misrepresentation of the article.

Re: Reality doesn’t exist until it is measured, quantum experiment finds

#163

Post by Strilanc »

andyl wrote: post #10

Lazy instantiation.

A lazily computed simulation would lazily compute entities not seeing the laziness. Laziness should have no measurable effect within the simulation, unlike quantum mechanics.

As an analogy, consider Hashlife [1]. It works very differently than your typical game of life implementation... but it still agrees on all the intermediate states! The board won't behave normally for most implementations, but end up in states spelling out "we know we're being cached hierarchically!" when you simulate with hashlife.

1: https://en.wikipedia.org/wiki/Hashlife

Re: Reality doesn’t exist until it is measured, quantum experiment finds

#164

Post by TheOtherHobbes »

visarga wrote: post #148
madaxe_again wrote: post #143

Earlier quoted context omitted.

Well, if you want to prove the simulation argument, all you have to do is simulate a reality for an individual at any time-dilation you like. With the parallel compute capabilities we are increasingly growing, simulating a small section of the universe at a large time-dilation should be within our grasp sooner than we think.

There is a limit to the total computation that can be done in the universe or with a certain limited energy/volume of space. It's caused by the slowness of signals traveling at light speed. They say probably a black hole is the best computational engine there is. https://en.wikipedia.org/wiki/Limits_to_computation

It's all fun and games until your solution blows up.

Re: Reality doesn’t exist until it is measured, quantum experiment finds

#165

Post by ak39 »

DennisP wrote: post #157
amelius wrote: post #128

Earlier quoted context omitted.

> developed the simulation we are living Well, the way I understand this, is that this result proves that we do NOT live in a simulation. Because if reality does not exist until measured, then we apparently cannot compute reality ahead of time. And if we cannot compute reality ahead of time, it does not exist yet.

If the purpose of the simulation is to simulate us, then it would make sense for it to not bother computing anything we don't measure.

https://en.wikipedia.org/wiki/If_a_tree_falls_in_a_forest

Quite sure there's a clever quip about this exact thing in terms of bits and bytes, I just haven't walked into that part of the forest yet.

Re: Reality doesn’t exist until it is measured, quantum experiment finds

#166

Post by Strilanc »

zw123456 wrote: post #86

And perhaps someday we'll get to meet the great programmer in the sky the developed the simulation we are living in and we will ask him why he designed it that way and he will say something like "oh I just wanted to optimize the code so I simply excluded reality subroutines when there were no beings looking. I just never thought you guys would notice. As soon as I saw that you guys noticed the flaw, I was going to lo…

That would quite possibly be the worst optimization ever.

"Yeah, I could have tracked and updated n values pretty cheaply, but instead I decided to exponentiate an exponentially huge matrix and use that to update a vector containing 2^n complex numbers associated with the possible assignments of the original n bits. Also, you should use bogosort. It's the best."

Re: Reality doesn’t exist until it is measured, quantum experiment finds

#167

Post by madaxe_again »

visarga wrote: post #148
madaxe_again wrote: post #143

Earlier quoted context omitted.

Well, if you want to prove the simulation argument, all you have to do is simulate a reality for an individual at any time-dilation you like. With the parallel compute capabilities we are increasingly growing, simulating a small section of the universe at a large time-dilation should be within our grasp sooner than we think.

There is a limit to the total computation that can be done in the universe or with a certain limited energy/volume of space. It's caused by the slowness of signals traveling at light speed. They say probably a black hole is the best computational engine there is. https://en.wikipedia.org/wiki/Limits_to_computation

Right, but you don't need to simulate an entire universe, just what's observable.

Re: Reality doesn’t exist until it is measured, quantum experiment finds

#168

Post by TheOtherHobbes »

antimagic wrote: post #154
zw123456 wrote: post #86

And perhaps someday we'll get to meet the great programmer in the sky the developed the simulation we are living in and we will ask him why he designed it that way and he will say something like "oh I just wanted to optimize the code so I simply excluded reality subroutines when there were no beings looking. I just never thought you guys would notice. As soon as I saw that you guys noticed the flaw, I was going to lo…

I always find it fascinating at just how much of our fundamental physics ends up being constraints on information movement. The laws of thermodynamics are about entropy, general relativity puts constraints on the movement of information (for example, Spooky Action as a Distance(tm) is faster than light, but you can't transmit information with it), the Uncertainty Principle puts limits on how much information you can…

It's hard to imagine a universe with infinite resolution. You'd effectively have an infinite number of bits in an infinitely dense space, which would potentially require infinite energy to flip.

But I suspect (on no basis whatsoever, except the fact that all previous metaphors have been wrong) that the "universe = Turing machine model" is wrong in some fundamental ways.

I have no idea what the universe is, but I'm open to the possibility that it isn't just an information processing system.

Re: Reality doesn’t exist until it is measured, quantum experiment finds

#169

Post by ak39 »

andy_ppp wrote: post #139
zw123456 wrote: post #86

And perhaps someday we'll get to meet the great programmer in the sky the developed the simulation we are living in and we will ask him why he designed it that way and he will say something like "oh I just wanted to optimize the code so I simply excluded reality subroutines when there were no beings looking. I just never thought you guys would notice. As soon as I saw that you guys noticed the flaw, I was going to lo…

The equivalent of a memory leak being spooky action at a distance?

No, I'm quite sure that would be black holes.

Edit: I think you're right. Black holes would be the equivalent of a segfault.

Re: Reality doesn’t exist until it is measured, quantum experiment finds

#170

Post by misnome »

Strilanc wrote: post #166
zw123456 wrote: post #86

And perhaps someday we'll get to meet the great programmer in the sky the developed the simulation we are living in and we will ask him why he designed it that way and he will say something like "oh I just wanted to optimize the code so I simply excluded reality subroutines when there were no beings looking. I just never thought you guys would notice. As soon as I saw that you guys noticed the flaw, I was going to lo…

That would quite possibly be the worst optimization ever. "Yeah, I could have tracked and updated n values pretty cheaply, but instead I decided to exponentiate an exponentially huge matrix and use that to update a vector containing 2^n complex numbers associated with the possible assignments of the original n bits. Also, you should use bogosort. It's the best."

That is assuming that whatever reality our simulation was running in followed the same rules.
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