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Author Topic:   Is the “Fine-Tuned Universe” an Illusion?
Son Goku
Inactive Member


(1)
Message 20 of 61 (891819)
02-12-2022 1:25 PM


Fine-Tuned
I wouldn't say it was N/A, it is possible to compute in certain models. In most Cosmological models it is actually true that our universe is "fine-tuned", as far as I understand the term. Only a vanishing amount of the parameter space for the Standard Model and also for theories of Quantum Gravity allow any complex structures to arise. And this is under any reasonable probability distribution.
Added to that if the world ran on any of the probability theories more general than quantum theory it would be impossible to learn/orient oneself or react coherently to the world and it would be intrinsically impossible to have life, although this is subtler than the point above.
I don't know what to make of it, it's a well known cosmology problem called the "naturalness" problem.

Replies to this message:
 Message 21 by AZPaul3, posted 02-12-2022 3:25 PM Son Goku has replied
 Message 23 by Tangle, posted 02-12-2022 4:09 PM Son Goku has replied
 Message 26 by Tanypteryx, posted 02-12-2022 5:59 PM Son Goku has replied

  
Son Goku
Inactive Member


Message 22 of 61 (891827)
02-12-2022 3:47 PM
Reply to: Message 21 by AZPaul3
02-12-2022 3:25 PM


Re: Fine-Tuned
The universe isn't infinite, so there wouldn't be an infinite amount of Earth-like planets. How special Earth is within our universe is hard to say, we need more data on extrasolar planets, but according to current physics the universe we have is extremely special within the space of possible universes.

This message is a reply to:
 Message 21 by AZPaul3, posted 02-12-2022 3:25 PM AZPaul3 has replied

Replies to this message:
 Message 24 by AZPaul3, posted 02-12-2022 5:19 PM Son Goku has replied

  
Son Goku
Inactive Member


(2)
Message 25 of 61 (891831)
02-12-2022 5:55 PM
Reply to: Message 23 by Tangle
02-12-2022 4:09 PM


Re: Fine-Tuned
Yeah like I definitely don't know. I mean ultimately QM already says whatever is going on isn't modellable fundamentally and we'll have to accept we're really only predicting the probabilities of future observations we choose to make rather than "the heart of things". Nima Arkani-Hamed is a physicist who has given some good heuristics that the Big Bang might be one of the "off-limits" unmodellable things according to QM.
Further evidence of the hand of Atum-Re and the eternal glory of Kemet

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Son Goku
Inactive Member


(1)
Message 27 of 61 (891833)
02-12-2022 6:01 PM
Reply to: Message 24 by AZPaul3
02-12-2022 5:19 PM


Re: Fine-Tuned
Like the Many-Worlds interpretation of QM?
Being honest I actually think it's completely silly and every physicist I've met who believed it was a cosmologist with serious gaps in their knowledge of QM. After over sixty years it still hasn't managed to achieve its most basic goal, i.e replicate the correct probabilities predicted by standard QM. I think it just comes from wanting to avoid certain implications of QM.

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 Message 24 by AZPaul3, posted 02-12-2022 5:19 PM AZPaul3 has replied

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 Message 28 by AZPaul3, posted 02-12-2022 6:51 PM Son Goku has replied

  
Son Goku
Inactive Member


(2)
Message 29 of 61 (891839)
02-13-2022 9:02 AM
Reply to: Message 26 by Tanypteryx
02-12-2022 5:59 PM


Re: Fine-Tuned
I may be wrong but it seems like there have been several changes in the fundamental parameters of this universe at specific stages in the development and evolution
So the parameters within our universe have changed over its life span, but the fine-tuning takes that into account. Both our parameters' values and their evolution are very fine-tuned.
It seems like that could also mean though, that only universes with that vanishing amount of parameter space can exist...
Maybe it's as simple as, this is the only way a universe can exist for 14 billion years.
Unfortunately most of the parameter space permits very long lived universes just like ours, so this idea won't work either. Not that it's a bad idea, it was one of the first things checked.
For peoples' interest one of the more interesting takes I've seen is that the different possible universes seen in the parameter space of quantum gravity theories might not actually be different possible universes but our own universe viewed from different perspectives (essentially as seen from different types of observers). However this idea is very underdeveloped and possibly completely wrong. If it was right these different subjective perspectives could not be logically combined, i.e. impossible to pass from these subjective perspectives to some kind of objective view.

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Son Goku
Inactive Member


(1)
Message 30 of 61 (891840)
02-13-2022 9:03 AM
Reply to: Message 28 by AZPaul3
02-12-2022 6:51 PM


Re: Fine-Tuned
What do you mean by the "measurement problem"?
People can mean a few different things by it, so I just want to know which is intended here in order to answer accurately.

This message is a reply to:
 Message 28 by AZPaul3, posted 02-12-2022 6:51 PM AZPaul3 has replied

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 Message 31 by AZPaul3, posted 02-13-2022 3:30 PM Son Goku has replied

  
Son Goku
Inactive Member


(4)
Message 32 of 61 (891842)
02-13-2022 3:58 PM
Reply to: Message 31 by AZPaul3
02-13-2022 3:30 PM


QM and Measurement
Okay so the way you have given it, there are basically two problems:
(a) The collapse of the wavefunction
(b) The fact that different measurements seem to have logically incompatible outcomes
So first of all a wavefunction is just a special case of a quantum state for when you're calculating position measurements. So I'll usually say quantum state instead.
So (a) first.
Looked at mathematically a quantum state has the same units as a probability distribution, obeys virtually all the same theorems as a probability distribution or generalisations there of. It can also be directly proven to be a generalisation of the probability distributions from regular "high-school" probability or statistics. There are a few proofs now in the literature that just assume a gambling agent wants to bet on the world in a coherent way (i.e. without contradicting themselves) and with a few assumptions on how they manage their bets you get a quantum state as a mathematical representation of those bets, but with different assumptions you get an old fashioned probability distribution as how they manage their bets.
For this reason I, along with the vast majority of people who work in QM, consider the quantum state (or wavefunction in the special case) to simply be a catalogue of an agents beliefs/credences/probabilities. It's not a material wave like an ocean wave.
Now probability theory has a method for computing an agent's new probabilities following an observation. You might know this as "Bayesian updating". The "collapse of the wavefunction" can be proven to be exactly this. It's simply the probabilities being updated in light of new information.
Since there are several mathematical proofs of this now, I consider this to be the answer to (a).
Now onto (b)
This is essentially the difference between classical probability and quantum theory.
In classical probability you consider a system to have a set of objective properties independent of observation. A particle has a position, momentum, energy, etc and you use probability theory to manage your ignorance of what values those properties have.
Quantum theory drops this assumption of observation independent objective properties. One's observations of a system produce numbers, but these can't be seen as reflecting properties of your system. Now probability theory is to manage your expectations of future observations, not ignorance of objective properties.
Once probability theory has been generalised to drop the "objective properties" assumption (this was the insight of Heisenberg) the resultant theory predicts the kind of incompatibilities you see in the double slit experiment.
Or one can go in the reverse direction. Simon Kochen and Ernst Specker showed that if certain kinds of incompatibilities show up in your experiments you can derive that there cannot be objective observation independent properties (Kochen-Specker theorem).
So like the vast majority of physicists I view the incompatibilities one sees in the double slit experiment as empirical evidence of the lack of objective properties/lack of an objective description of physical systems. Not a problem, but the insight of QM.
Edited by Son Goku, : Typos

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 Message 31 by AZPaul3, posted 02-13-2022 3:30 PM AZPaul3 has replied

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 Message 33 by AZPaul3, posted 02-13-2022 5:56 PM Son Goku has replied

  
Son Goku
Inactive Member


(3)
Message 34 of 61 (891844)
02-13-2022 6:41 PM
Reply to: Message 33 by AZPaul3
02-13-2022 5:56 PM


Re: Objective Reality
Some of what follows might seem pedantic, or maybe stuff you already appreciate. due to it being hard to know what is being followed by somebody else from text alone and for others I will very explicit on certain points.
We can use wave function and quantum state interchangeably. At this level it is permissible, yes?
Yeah the terminology doesn't matter much here.
I hope no one thinks the wave function has a physical manifestation. But it is the reality we experience.
Let me start with an example.
Imagine somebody rolls a dice in a closed room. You who don't know the outcome assign probabilities as follows:
1 2 3 4 5 6
1/6 1/6 1/6 1/6 1/6 1/6
i.e. you give a 1/6 chance of each outcome. That list of 1/6 values in the second row is a probability distribution. The wavefunction is the exact same thing as that list. A list of chances to see certain events.
You wouldn't say that probability list is the "reality you experience". It's a calculational device that encodes expectations of what die roll you might see. The die roll is the actual reality you experience, not the probability list. It's the same with the wavefunction, it has no physical reality at all.
Same with how the odds on a horse race have no physical reality. The horses, jockeys, the race track do, but not the odds.
And the result of a measurement reveals the most probable value we will see at any specific moment in time
It reveals one of the possible values, not necessarily the most probable one. It's not always the horse with the best odds that wins.
Yet when we measure the system the “most” probable result will differ depending on how the system is measured. Different measurements seem to alter what is most probable in a set objective system.
So I'll take as a case the double slit experiment. You mean for example if you check the slits vs don't check the slits the locations where the electron/photon/etc will most likely land changes? If so then the next quote deals with this....
If I read your post properly your solution to this is to use Heisenberg’s work to do away with objective reality. How does that work?
Because the only way the double slit experiment is contradictory is if you think there is some system with objective properties evolving under certain rules/laws and your measurements merely record where it happened to be by the time it hit the screen.
Consider the passage through the slit to be a variable with two possible values:
Slit = Upper
or
Slit = Lower
If you don't check the Slit it leaves this variable undefined:
Slit = NULL
And Quantum Mechanics gives different answers for how likely it is to strike different parts of the screen depending on whether the Slit value was measured vs if it wasn't. It keeps track of which variables have obtained a value due to you measuring them and which haven't and the calculations get altered depending on which variables have become defined/gained a truth value.
This is paradoxical if you think these things have truth values independent of observation. It is not when you realise they only have truth values because of observation*.
Heisenberg conjectured, unlike everybody else at the time, that the issues with atomic spectra were not problems with formulating new laws or equations. Instead he said keep the old equations but drop the assumption that the variables have values at all times independent of observation. Removing that assumption gave him Quantum Theory. A new way of keeping track of your probabilities that doesn't assume objective properties exist.
*And note there is not some mechanical process to be found which "generates" the observed values. You select which variables are going to obtain values by your choice of observations and they will be given a value, but there is no process producing that value to be discovered. Observation/Measurement is a primitive in QM not a derived/emergent outcome of "deeper" properties or processes.

This message is a reply to:
 Message 33 by AZPaul3, posted 02-13-2022 5:56 PM AZPaul3 has replied

Replies to this message:
 Message 35 by AZPaul3, posted 02-13-2022 8:22 PM Son Goku has replied

  
Son Goku
Inactive Member


Message 37 of 61 (891847)
02-14-2022 5:36 AM
Reply to: Message 35 by AZPaul3
02-13-2022 8:22 PM


Re: Objective Reality
Actually, no I don’t. I certainly cannot argue your point. But, from a long time trying, the more I study QM the more EPR-like I become. We’re missing something.
That's a common feeling, but I want to strongly emphasise how wrong it is.
The lack of an objective description for physical systems first showed up in probing atomic spectra and required quantum mechanics. Quantum Mechanics was then converted into Quantum Field Theory to handle subatomic phenomena and has continued to hold down to length scales over a billion times smaller than what QM was originally created for. And yet still the idea of the lack of an objective description holds. Not just holds up, but in fact predicts the correct observations.
In fact the lack of an objective description in QM is strengthened even more in QFT. In QM there might not have been an objective description of an electron but at least you could say there was an electron or your system had 3 or 4 or 5 electrons in it etc.
In QFT even particle number has no objective content to it. The Unruh effect for example shows that if I perform a scan on your body to count the number of atoms, the exact number I get has a probabilistic distribution, i.e. there is no actual number of atoms in your body until I perform the scan. Even further an observer accelerating with respect to you has a different "most likely number of atoms", a different probability distribution for atom count and can sometimes produce a count an stationary observer never would.
So probing deeper scales required abandoning the "objectivity" concept even more.
Further more we now have No-Go theorems such as Hardy's theory, GHZM theorem, Kochen-Specker theorem and newer strong ones that show no theory which postulates an objective description can possibly succeed in matching current evidence.
So we've still plenty to figure out, but if we find out QM is incorrect the only way it is going to go is an even less "objective" theory. Such theories do exist, the most studied is the so-called Popescu-Rohrlich box world, which is far less objective than even QM. So far no such "more subjective" theory has been required empirically so we conservatively stick to QM. They're weird theories, I'll say more about them in responding to nwr's interesting post below.

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Son Goku
Inactive Member


(1)
Message 38 of 61 (891848)
02-14-2022 6:21 AM
Reply to: Message 36 by nwr
02-13-2022 9:32 PM


Re: Objective Reality
So this is a very good launching point for discussing objectivity in QM. I'll start by quoting UC Santa Cruz and Rutgers professor Thomas Banks' recent (2018) undergraduate textbook on quantum theory "Quantum Mechanics: An Introduction" where he says on p.16 of the 2021 paperback reprint:
Objectivity Reality is an Emergent Phenomena
Quantum Theory, like any probability theory, is used to model agents updating their expectations in light of experience. We can then model these agents exchanging and communicating information.
In Classical Probability theory under certain very mild conditions these agents when presented with the same data will eventually start to converge on similar probability distributions for future observations. These probability distributions and the process of their convergence is completely consistent with the existence of a single underlying description of physical reality. And so the convergence process can be read as "getting closer and closer" to this objective TRUE description of things.
Quantum Theory is quite different. The way the probabilities behave is not consistent with a single underlying description, i.e. a "way the world is". For this reason agents are not guaranteed to converge on a single set of expectations.
However one can show that the probabilities and expectations concerning large scale features of the world, e.g. the location of a tree, the height of Khufu's pyramid, do show a convergence and other features that are exactly like what you'd have in Classical Probability. And so a "layer" of reality emerges that agents can communicate stably about and agree on.
The existence of such a layer is of certain critical importance since otherwise it would be very hard to imagine how we could do science. The fact that QM requires the emergence of such a layer in order to be scientifically useful was a major concern of Neils Bohr:
"Bohr Collected Works Volume 7 p349" writes:
...that by the word “experiment” we refer to a situation where we can tell others what we have done and what we have learned and that, therefore, the account of the experimental arrangement and of the results of the observations must be expressed in unambiguous language with suitable application of the terminology of classical physics
The emergence of an objective layer is closely tied to thermodynamic processes often called "irreversible" and the large size of macroscopic bodies. Ultimately QM tells us we can only speak objectively about occurrences in this macroscopic layer of the world:
"Bohr Collected Works Volume 7 p390" writes:
In this connection, it is also essential to remember that all unambiguous information concerning atomic objects is derived from the permanent marks—such as a spot on a photographic plate, caused by the impact of an electron—left on the bodies which define the experimental conditions. Far from involving any special intricacy, the irreversible amplification effects on which the recording of the presence of atomic objects rests rather remind us of the essential irreversibility inherent in the very concept of observatio
Thomas Banks in the textbook above (p.223 in 2021 reprint) makes a similar point that the scientific content of QM is:
"Banks" writes:
To compute the probabilities for future events conditioned on the result of some particular event that affected a collective coordinate of a macroscopic body
"Collective coordinate" is basically jargon for "large scale feature" like the height of Khufu's pyramid rather then specific details of its atoms.
This does have knock on effects such as that it's not strictly correct to say I am "made of atoms" since it is impossible to conceive of an atom as an objective object, as Heisenberg often said:
"Heiseneberg. Physics and Philosophy Penguin Reprint p83" writes:
They* would prefer to come back to the idea of an objective real world whose smallest parts exist objectively in the same sense as stones and trees exist, independently of whether or not we observe them. This however is impossible...
*He means people who oppose QM
There's a book by the French physicist Roland Omnès "The Interpretation of Quantum Mechanics" where he carefully studies the use of language and logic in QM. He rightly points out the inconsistent of statements like "I'm made of atoms" or "fission works by neutrons splitting atomic nuclei" and has a section devoted to "Reliable Properties" which are essentially stories like this that treat atomic phenomena as if they were objective, i.e. effective metaphors, and he carefully works in what situations the stories work and when they break down. They're surprisingly fragile in the case of fission for example, it's not hard to derive in a few lines a basic contradiction in the typical account of fission. I can do it if anybody wants.
Popescu-Rohrlich theories I mentioned above are more extreme than QM in that they have no "Reliable Properties", i.e. it's never valid to use these stories where you pretend atoms etc are objective objects. You and other agents have to agree to only ever communicate about the objective layer and never say anything beyond that, even as an effective metaphor. It might turn out that's where we have to go for a proper description of gravity. Time perhaps will tell.

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Son Goku
Inactive Member


Message 40 of 61 (891850)
02-14-2022 10:03 AM
Reply to: Message 36 by nwr
02-13-2022 9:32 PM


Re: Objective Reality
I have not ditched "objective reality". But I have changed what I mean by that term.
Just more as a check, Heisenberg did say you have to ditch it below a certain length scale otherwise you'd model Helium wrong. I assume this would be incorporated within what you are saying by saying Helium isn't fully in "objective reality", i.e. you don't ditch objective reality but accept it is verification and communication based and that some things, e.g. Helium, don't fully fall into it.
Edited by Son Goku, : Format

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Son Goku
Inactive Member


(2)
Message 42 of 61 (891852)
02-14-2022 11:04 AM
Reply to: Message 41 by Tanypteryx
02-14-2022 10:53 AM


Re: Full justification for EvC's existence.
No worries. I had a hard time with QM initially as well.
Later today I'll post the Hardy Paradox as it's usually considered the easiest demonstration of the heart of QM.

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Son Goku
Inactive Member


(1)
Message 43 of 61 (891853)
02-14-2022 12:02 PM


Hardy Paradox
So here's the simplest demonstration of QM's odd features.
We consider two electrons and for each one we can measure either the orientation of its spin (clockwise or anticlockwise) or how much Energy it has (high or low).
I'll use shorthand. E1 means Energy of the first particle. S2 means Spin of the second particle. I'll use +,- for each of the two outcomes. "E1 = +" means the Energy of the first particle was high. "S2 = +" means the spin of the second particle was clockwise.
Empirical facts:
A silver oven can be set up to emit electrons in pairs with the following empirical facts following.
(1) "E1 = +" implies "S2 = +" (The first electron being measured as high energy is always accompanied by the second electron spinning clockwise)
(2) "S2 = +" implies "S1 = -" (The second electron spinning clockwise implies the first one is anti-clockwise always)
(3) "S1 = -" implies "E2 = -" (The first electron spinning anti-clockwise implies the second one is at low energy always)
Contradiction:
Now let's say I am going to measure the Energies of both electrons. That is I will measure E1 and E2.
I measure E1 and find the electron has high energy, "E1 = +".
Now I take the three statements above and consider them as statements about objective properties the electrons coming from the oven possess independent of observations.
Since I just measured "E1 = +" I can use the first statement (1) to figure out that "S2 = +", i.e. that the second particle is spinning anti-clockwise.
Knowing that I use statement (2) to infer "S1 = -". Finally I use (3) to infer "E2 = -".
Thus I estimate that the second particle must be in a state of low energy.
However when I measure such systems I find 1/12 of the time the second electron has high energy. This probability is predicted by QM, but is in direct contradiction to the conclusion reached by observation independent properties.

  
Son Goku
Inactive Member


(2)
Message 45 of 61 (891856)
02-14-2022 2:02 PM
Reply to: Message 44 by nwr
02-14-2022 1:43 PM


Re: Objective Reality
This seems to fit with what I know of the QM point of view. When we thingify the world, that gives us a world of things. But that seems to be pretty much the same idea as collapsing the wave function. All of classical physics is about the things that we come up with as we thingify the world. And the uncertainty in how we do this seems to relate to QM uncertainty.
Thanks for answering. If you're interested your description here can actually be formalised. "Thingifying" is mathematically formalised as placing statements you make into a Boolean algebra. QM describes the world via a collection of Boolean algebras that don't perfectly overlap/agree and the degree they fail to overlap is exactly Heisenberg's uncertainty. So this seems like a very nice way to approach it to me.
I know the science journalist Amanda Gefter is writing a book sort of bringing together human cognition and QM and from what I've seen of it it sounds very similar to what you are saying. I'm no expert on cognition, but it might be something you'd enjoy once she publishes it.
Edited by Son Goku, : Typos

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Son Goku
Inactive Member


(5)
Message 51 of 61 (891864)
02-15-2022 3:35 AM
Reply to: Message 47 by AZPaul3
02-14-2022 7:05 PM


Re: Many Worlds
Many worlds (MW), I am informed, does away with any wave function collapse. Determinism and objective reality are preserved
You said in one early message that you thought MW was completely silly
For specific mathematical reasons. It's nothing to do with the idea that multiple alternate timelines is inherently silly.
Many Worlds is a specific idea that requires certain theorems to hold up in order to work. After over sixty years they never have. For that reason I find continued investigation of it to be pointless. There have been several examples recently where it seems impossible to get any numbers (let alone the correct ones) out of it.
It's just a pile of words rather than a cogent idea.
I have found on the internet many of these ideas, e.g. Bohmian Mechanics, Many Worlds, get far more coverage than they do in actual physics research. So this can make them seem more prominent than they really are. Open an academic book on the Fundamentals/Interpretation of Quantum Mechanics like Asher Peres' "Quantum Theory: Concepts and Methods" or Roland Omnès' "The Interpretation of Quantum Mechanics" with thousands of citations each and you'll see Many Worlds and Bohmian Mechanics dismissed in one or two paragraphs.
Lots of recognized world-class egg heads work on extra dimensions, symmetries, etc. It gives them a new playground
That stuff has nothing to do with Many Worlds. Spacetime having additional dimensions, or finding new symmetries is unrelated to the Many Worlds idea.
The fragmentation says, to me, that we haven’t found the reality. We are still missing something
But none of this really involves a questioning of QM back in the direction of "objective" physics. They have disagreements over the exact form of where Quantum Gravity should go, but nobody highly cited in the field is actually proposing a return to the objective picture of the world. In fact most like Nima Arkani-Hamed, Raphael Bousso or Thomas Banks or hundreds of others I could name are advocating that it should be more subjective.
MW restores my beloved objective reality
As I said above the issue is it doesn't work. And there was never any scientific motivation for it aside from this intellectual prejudice.
In summary:
Objective reality has turned out to be empirically incorrect. In Quantum Mechanics you can show that large scale features of objects, like those in the day to day world, are capable of being objectively described. However at a fundamental level the world is not. One has to get used to it just like several other scientific ideas that changed our view of the world
Edited by Son Goku, : Typo

This message is a reply to:
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Replies to this message:
 Message 52 by AZPaul3, posted 02-28-2022 1:08 AM Son Goku has replied

  
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