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Physicists provide support for retrocausal quantum theory

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Re: Physicists provide support for retrocausal quantum theory

#81

Post by clock_tower »

mabbo wrote: post #72
ridewinter wrote: post #50

Earlier quoted context omitted.

That's exactly what I'm saying! All other explanations say something confusing and obfuscating like "there are no photons". Many-worlds keeps it simple and says "there are photons, and the reason they behave like that is because they're interacting with parallel universes". You can't explain why they behave like that, so you say that the photon isn't really real, and have a complicated explanation of it.

> All other explanations say something confusing The problem here is that you want an explanation that is intuitive and easy for you to grasp. What if the true answer is one that is too hard for you (or maybe any human) to easily understand? Our brains aren't evolved for understanding the true nature of the universe, they're evolved for reproducing and surviving in a very simple world. We're using re-purposed hardwar…

> Our brains aren't evolved for understanding the true nature of the universe, they're evolved for reproducing and surviving in a very simple world.

Absolutely. For survival-to-reproduction -- and for quite a bit more than that -- Aristotle's physics are enough; but they're full of absurdities and strange edge cases when you look at them more carefully. To explain the flight of an arrow, you need Newton... and then you start noticing that Newton has edge cases too.

I don't pretend to understand quantum mechanics, but I'm fine with cheering from the sidelines on that one. Whatever the answers are at that level, they certainly seem to be shaping up to be something deeply unlike our intuitions...

Re: Physicists provide support for retrocausal quantum theory

#82

Post by mikeash »

clock_tower wrote: post #81
mabbo wrote: post #72

Earlier quoted context omitted.

> All other explanations say something confusing The problem here is that you want an explanation that is intuitive and easy for you to grasp. What if the true answer is one that is too hard for you (or maybe any human) to easily understand? Our brains aren't evolved for understanding the true nature of the universe, they're evolved for reproducing and surviving in a very simple world. We're using re-purposed hardwar…

> Our brains aren't evolved for understanding the true nature of the universe, they're evolved for reproducing and surviving in a very simple world. Absolutely. For survival-to-reproduction -- and for quite a bit more than that -- Aristotle's physics are enough; but they're full of absurdities and strange edge cases when you look at them more carefully. To explain the flight of an arrow, you need Newton... and then y…

Feynman said, "I think I can safely say that nobody understands quantum mechanics." This is a guy who won the Nobel Prize for work in quantum mechanics.

QM does not line up with human intuition at all. It looks like this is a fundamental issue with how the universe works, not a problem with our explanations. And really, that shouldn't be any surprise. There's no reason to expect the universe's workings to match our intuition in any situation that's substantially different from what our intuition evolved in.

Re: Physicists provide support for retrocausal quantum theory

#83

Post by nilson »

ridewinter wrote: post #15

The many-worlds interpretation of quantum mechanics is the only one that's easy to understand. All others seem to bend over backwards to realistically explain quantum effects. It's so rare to find clear explanations, but they do exist. My favorite from David Deutsch, a main creator of the idea of quantum computing: To those who still cling to a single-universe world-view, I issue this challenge: explain how Shor’s al…

im not "clinging to single universe world view" but i got 2 questions: 1. has this alghoritm actually been executed somewhere? 2. does this mean there is infinite storage posibillity to store any data you want or it must be "special" data. and how much time does it take to access any segment of this data.

if the answer is no to both question then my answer is: "it doesn't work."

Re: Physicists provide support for retrocausal quantum theory

#84

Post by whyever »

mikeash wrote: post #65
ridewinter wrote: post #44

Earlier quoted context omitted.

Math is used to explain the universe. It isn't an explanation in of itself. We never progressed anywhere by saying "something just works" and leaving it at that. Challenge yourself.

Seems like it's the opposite to me. We never progressed anywhere with "explanations." Progress comes when those explanations are condensed to testable mathematics. I'm curious as to what you think consists of "an explanation" that's more useful than mathematics. Let's take a simple classical phenomenon to keep it easy, such as kinetic energy. The mathematical statement is E_k = 1/2 m v^2. What non-math explanation wo…

Just the math is not enough, you need some connection to reality. For instance, your formula does not describe reality for large v. This can be tested.

Re: Physicists provide support for retrocausal quantum theory

#85

Post by Tossrock »

rthomas6 wrote: post #42

This reminds me a lot of the sci-fi novel Anathem by Neal Stephenson. Trying to be spoiler-free as possible, in the book, the many-worlds interpretation of quantum mechanics is the correct one, and the worlds lie on a directed acyclic graph, meaning that the flow of information can only move in one direction along the universes. So in the same way information can only travel in one direction in time (into the future)…

spoilers I think he implies pretty heavily that the Rhetors actually CAN influence the past, through a mechanism very similar to that described in the article - "choosing" which way an event happened in the past. Their powers work at Narrative scale though, not just experimental observation.

Re: Physicists provide support for retrocausal quantum theory

#87

Post by mindviews »

woliveirajr wrote: post #11

> First, to clarify (...) It does not mean that signals can be communicated from the future to the past(...) instead, retrocausality means (... it) can influence the properties of that particle (or another particle) in the past, even before the experimenter made their choice. In other words, a decision made in the present can influence something in the past. So, hard to explain in layman words: future can't transmit…

We should be talking about "consistency" being the fundamental idea, not causality. I think "retrocausality" is an especially distracting choice of words.

I find the clearest way to think about this is in terms of Feynman Diagrams. Here's a quick intro to some of the rules: http://bolvan.ph.utexas.edu/~vadim/classes/2008f.homeworks/Q... If you're not familiar, ignore the math and just look at the pictures on the first couple of pages.

Take a simple diagram of a photon interacting with an electron (google QED Vertex). Here's a very tiny ASCII version: ~~ represents a electron and a positron colliding/annihilating to create a photon. Turned another way you could have a photon and electron as input, and an electron with a changed momentum as the output. For the last case you could say the electron absorbed the photon. But really, these are all the exact same pattern just rotated around in spacetime. So, what is causation? If it's all the same pattern, it's clear that consistency with the pattern is more important than the direction of time's arrow.

Speaking very loosely now (there are a bunch of constraints and caveats on what I'm about to say), you can plug these diagrams together to make arbitrarily complicated internal structures. But if they have the same inputs and outputs, they are in a sense consistent. And if you do it just right you can constrain which types of patterns can link up with the one you've set up. So, in the end, only patterns that are consistent with your setup can happen. Which is pretty much what this article is describing.

Re: Physicists provide support for retrocausal quantum theory

#88

Post by monktastic1 »

alasdair_ wrote: post #78
rf15 wrote: post #35

Earlier quoted context omitted.

don't remind me that people actually believe that you can infer the existence of a simulation only with data points that are created and controlled by it.

There doesn't seem to be anything wrong with this basic idea. As a (bad) analogy, think about how computer code can be written to detect whether or not it is running inside a virtual machine or on a "real" device. It's usually almost impossible to tell but by probing at the extremes and forcing the system to do things that never happen under common usage, it's possible. (It's also possible to break out of the system…

The difficulty is that we already know something about how computers work. What's to say that time, space, logic, reason, mathematics are even things in the "base" reality?

Re: Physicists provide support for retrocausal quantum theory

#89

Post by gnaritas »

ridewinter wrote: post #50
TheOtherHobbes wrote: post #46

Earlier quoted context omitted.

There are no photons. There are only photon-like events, with associated probabilities and scattering processes. It's a lot easier to assume that reality is the visible output of an heroically counter-intuitive but relatively tractable probabilistic calculation process, than it is to assume there are infinite universes with poorly defined boundary conditions between them and even more poorly defined properties, and t…

That's exactly what I'm saying! All other explanations say something confusing and obfuscating like "there are no photons". Many-worlds keeps it simple and says "there are photons, and the reason they behave like that is because they're interacting with parallel universes". You can't explain why they behave like that, so you say that the photon isn't really real, and have a complicated explanation of it.

Inventing infinite universes to explain something isn't simpler than "there are no photons"; it might please you more, but infinite universes is the more complex explanation as it essentially asserts magic. It's far simpler to believe we don't fully understand quantum mechanics yet than it is to believe there are an infinite number of parallel universes.

Re: Physicists provide support for retrocausal quantum theory

#90

Post by TheOtherHobbes »

ridewinter wrote: post #50
TheOtherHobbes wrote: post #46

Earlier quoted context omitted.

There are no photons. There are only photon-like events, with associated probabilities and scattering processes. It's a lot easier to assume that reality is the visible output of an heroically counter-intuitive but relatively tractable probabilistic calculation process, than it is to assume there are infinite universes with poorly defined boundary conditions between them and even more poorly defined properties, and t…

That's exactly what I'm saying! All other explanations say something confusing and obfuscating like "there are no photons". Many-worlds keeps it simple and says "there are photons, and the reason they behave like that is because they're interacting with parallel universes". You can't explain why they behave like that, so you say that the photon isn't really real, and have a complicated explanation of it.

You have an unusual definition of simple.

If you still don't understand, consider this: MWI only works if photons are kept in a coherent superposition of states.

Supposedly this means each universe defines a state.

But... the photons have to be isolated from their respective universes. Otherwise coherence is broken and you no longer have your coherent superposition.

Given that, what's the rationale for inventing an entire universe around a quantum particle if the math only works if you keep that particle isolated from everything else in that universe?

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