There's no such thing as objective reality

[Eldorado]

Back in 1961, the Nobel Prize–winning physicist Eugene Wigner outlined a thought experiment that demonstrated one of the lesser-known paradoxes of quantum mechanics. The experiment shows how the strange nature of the universe allows two observers—say, Wigner and Wigner’s friend—to experience different realities.

Since then, physicists have used the “Wigner’s Friend” thought experiment to explore the nature of measurement and to argue over whether objective facts can exist. That’s important because scientists carry out experiments to establish objective facts. But if they experience different realities, the argument goes, how can they agree on what these facts might be?

Full 2019 article at MIT: Technology Review

Edited November 26, 2020 by Eldorado

[XenoFish]

Quote

Nevertheless, the work has important implications for the work of scientists. “The scientific method relies on facts, established through repeated measurements and agreed upon universally, independently of who observed them,” say Proietti and co. And yet in the same paper, they undermine this idea, perhaps fatally. From the link.

Nothing is true, everything is permitted.

[zep73]

The article is from March 12, 2019.

[eight bits]

16 minutes ago, zep73 said:

The article is from March 12, 2019.

In your reality.

[acute]

Well..... It appears that these stringy loopy particle thingies can't decide where they are, until we perceive them, then they come off the fence.

We will never explain our 'reality' while we are stubbornly clinging to our current laws of physics.

[simplybill]

From the article:

“But Proietti and co’s result suggests that objective reality does not exist. In other words, the experiment suggests that one or more of the assumptions—the idea that there is a reality we can agree on, the idea that we have freedom of choice, or the idea of locality—must be wrong.“

I find the bolded phrase puzzling. It appears to me that the researchers are assuming their individual experiments have reached a conclusion, whereas instead they should take a step back and consider the old adage: “There’s more here than meets the eye.” If the perspectives of Mr. Wigner and his friend are at odds, then they should collaborate with one another rather than create a rivalry. 

[Mr Walker]

On 11/27/2020 at 12:28 AM, Eldorado said:

Back in 1961, the Nobel Prize–winning physicist Eugene Wigner outlined a thought experiment that demonstrated one of the lesser-known paradoxes of quantum mechanics. The experiment shows how the strange nature of the universe allows two observers—say, Wigner and Wigner’s friend—to experience different realities.

Since then, physicists have used the “Wigner’s Friend” thought experiment to explore the nature of measurement and to argue over whether objective facts can exist. That’s important because scientists carry out experiments to establish objective facts. But if they experience different realities, the argument goes, how can they agree on what these facts might be?

Full 2019 article at MIT: Technology Review

Of course there is an objective reality. It is the reality which existed before humans had evolved enough to question the nature of reality and will remain after humans are extinct 

Humans have a "perception of reality" and if you  define that  perception as reality , then an objective reality doesn't exist but, given tha t reaiity exists outside our perceptions and minds, it has its own objective existence.  

[onlookerofmayhem]

Hey @zep73, found it.

So the way I interpreted Sabine's explanation is that Wigner's thought experiment is not well represented by the photon experiments because a photon is not a conscious observer.

I'm not really sure why there's controversy over the thought experiment in the first place.

When the friend makes the measurement, the wave function collapses and the measurement is what it is.

Just because Wigner is outside the door and doesn't know what the measurement is doesn't mean that the superposition still exists, right?

This is where I'm having trouble. 

So, he's outside the door saying, "The measurement could be A or B, but I don't have the results of the experiment."

Isn't similar to if the friend flipped a coin and looked at it before telling Wigner what it came up as? Just because Wigner doesn't know if it's heads or tails, he can't possibly think it could be still be both knowing that the coin has been flipped. It has to just be one or the other.

Thanks in advance if you could help me or point to what I'm missing.

Edited February 20, 2022 by onlookerofmayhem
Grammar

[ChrLzs]

Like OLOM, I don't get it.  Can anyone provide a real world situation where this becomes an issue beyond what we already know about Quantum mechanics and concepts like the Uncertainty Principle?

Also, as a passing comment, the article is very poorly written, and it is not at all clear exactly what they did.  I'd like to see a step-by-step description of everything they did, plus all the recorded data, rather than that handwaved and confusing 'overview', which includes non-specific waffle like this:

Quote

They use these six entangled photons to create two alternate realities—one representing Wigner and one representing Wigner’s friend. Wigner’s friend measures the polarization of a photon and stores the result. Wigner then performs an interference measurement to determine if the measurement and the photon are in a superposition.  The experiment produces an unambiguous result.

Read that carefully - do you understand what is the nature of the two realities?  The ones that are supposedly 'real', and yet they use the term 'representing' twice - why would you say they are represented rather than actual?  These two 'realities' are supposedly in conflict, and I want to know what were the procedures by which they came to be, and what were the actual results... 

If you do understand, then please explain, in words that will make sense to one not trained in untangling circumlocution.......

Edited February 20, 2022 by ChrLzs

[taniwha]

10 hours ago, ChrLzs said:

Like OLOM, I don't get it.  Can anyone provide a real world situation where this becomes an issue beyond what we already know about Quantum mechanics and concepts like the Uncertainty Principle?

Also, as a passing comment, the article is very poorly written, and it is not at all clear exactly what they did.  I'd like to see a step-by-step description of everything they did, plus all the recorded data, rather than that handwaved and confusing 'overview', which includes non-specific waffle like this:

Read that carefully - do you understand what is the nature of the two realities?  The ones that are supposedly 'real', and yet they use the term 'representing' twice - why would you say they are represented rather than actual?  These two 'realities' are supposedly in conflict, and I want to know what were the procedures by which they came to be, and what were the actual results... 

If you do understand, then please explain, in words that will make sense to one not trained in untangling circumlocution......

Simply put, you don't know, but someone else does

[GlitterRose]

It's not that there's no such thing as the physical world/objective reality. The point is that it doesn't necessarily merit the importance we afford it.

[ChrLzs]

2 hours ago, taniwha said:

Simply put, you don't know, but someone else does

Almost.  But many things cannot be put simply, and also I'm not an expert on many, many topics.  So, on those, I generally leave the hard yakka up to those who are working in that field.

But it's not just that simple, as there are two aspects to the proverbial "Good Science".  First up, the observations and experiments have to be sound and properly documented (so as to be repeatable and verifiable).  Second, those who present the science need to do so in a way that a reasonably literate person can understand what they did, and what they theorise.

Either I'm not reasonably literate, or they are failing..  

If it's the former, I apologise and will try harder.  But it seems I'm not alone in not getting it, judging from the posts above.

[ChrLzs]

For those wishing to exercise (twist?) their brains, I've found the full paper here:

https://www.science.org/doi/10.1126/sciadv.aaw9832

Maybe I'll get brave and try to read/understand it - but at this point I just don't have time.

[zep73]

Quote

I get that's she's describing the math. But correct me if I'm wrong, but isn't that what most of quantum physics is about? The math to describe what is being observed?

I'm in no way, shape or form an expert in QM, but I try to follow as best I can. Not sure of your expertise in the field, but maybe you can help me.

This may not be the right thread for this so I'm going to try to find the appropriate one.

To draw a parallel: In physics, math is what bookkeeping is to a company. You need it to know if you're doing the right thing, like making more money than you're spending, or to show the IRS when they drop by, to prove you've paid your dues.
In physics, every time someone suggests a new hypothesis, the first thing the reviewers look at is the math. To make sure it's even possible, that it fits the rules of nature. That it's compatible with older proven theories.

In QM it's limited how many experiments you can perform, so if you really want to investigate something, math is the most cooperative tool. But it's important to remember that the math is based on real life experiments, not the other way around, so if there's a disagreement between them, the math must be corrected, not the experiment. What I'm trying to say is that you can't make the mysteries go away, just by focussing on the math. The math might blur them, and make them seem less spooky, but it's a charade.

22 hours ago, onlookerofmayhem said:

Just because Wigner is outside the door and doesn't know what the measurement is doesn't mean that the superposition still exists, right?

This is where I'm having trouble. 

So, he's outside the door saying, "The measurement could be A or B, but I don't have the results of the experiment."

Isn't similar to if the friend flipped a coin and looked at it before telling Wigner what it came up as? Just because Wigner doesn't know if it's heads or tails, he can't possibly think it could be still be both knowing that the coin has been flipped. It has to just be one or the other.

Thanks in advance if you could help me or point to what I'm missing.

For Wigner, the superposition remains until he has measured the particle himself. Even if Alice does it before him. It makes no sense, but it's true.
If Alice tells him what she saw, he will see the same. If she doesn't, it's a new "collapse" - as if Alice never measured it.

This only makes sense if reality is a personal subjective experience. Each person has their own version. Matter is an experience, not a thing.

 

Edited February 21, 2022 by zep73

[+Liquid Gardens]

12 hours ago, zep73 said:

If Alice tells him what she saw, he will see the same. If she doesn't, it's a new "collapse" - as if Alice never measured it.

Not that I'm following any of this, but what if Alice lies, what's he see then?

[zep73]

59 minutes ago, Liquid Gardens said:

Not that I'm following any of this, but what if Alice lies, what's he see then?

As far as I know, that has not been tested.

[Crazy Horse]

On 11/26/2020 at 1:58 PM, Eldorado said:

Back in 1961, the Nobel Prize–winning physicist Eugene Wigner outlined a thought experiment that demonstrated one of the lesser-known paradoxes of quantum mechanics. The experiment shows how the strange nature of the universe allows two observers—say, Wigner and Wigner’s friend—to experience different realities.

Since then, physicists have used the “Wigner’s Friend” thought experiment to explore the nature of measurement and to argue over whether objective facts can exist. That’s important because scientists carry out experiments to establish objective facts. But if they experience different realities, the argument goes, how can they agree on what these facts might be?

Full 2019 article at MIT: Technology Review

I would say that objective facts can only be ascertained when all parties agree upon a standard and comprehensive understanding of our collective existence.

Then, any difference can be measured, weighed, and accounted for.

Wigner, and Wigner's mate, are experiencing life subjectively..

 

[jmccr8]

1 hour ago, Crazy Horse said:

I would say that objective facts can only be ascertained when all parties agree upon a standard and comprehensive understanding of our collective existence.

Then, any difference can be measured, weighed, and accounted for.

Wigner, and Wigner's mate, are experiencing life subjectively..

 

Hi Crazy Horse

If one person farts in a crowded elevator I am pretty sure they all share an objective reality.

[Crazy Horse]

1 hour ago, jmccr8 said:

Hi Crazy Horse

If one person farts in a crowded elevator I am pretty sure they all share an objective reality.

Hi Jay..

Farts come and go..

The memory lingers..

And life goes on.

My friend..

[onlookerofmayhem]

18 hours ago, zep73 said:

For Wigner, the superposition remains until he has measured the particle himself. Even if Alice does it before him. It makes no sense, but it's true.
If Alice tells him what she saw, he will see the same. If she doesn't, it's a new "collapse" - as if Alice never measured it.

Is this just in the thought experiment or is it reflected in the actual experiment(s)?

Doesn't Alice's initial measurement make it impossible for Wigner to measure the state of the same particle? Is it even possible to measure a particle twice? And get different results?

As far as I understand, the wave function collapses and the superposition doesn't exist because the measurement is made. The wave function is just describing the probability of possible states and once the measurement is made the state is known. To say that the superposition still exists to Wigner because he didn't take a measurement nullifies the fact that Alice did already make a measurement? 

I tried reading the link @ChrLzs provided and it's definitely above my pay grade.

The main problem I'm having is relating the actual experiment to the thought experiment.

Thanks for your help.

[zep73]

11 minutes ago, onlookerofmayhem said:

Is this just in the thought experiment or is it reflected in the actual experiment(s)?

Doesn't Alice's initial measurement make it impossible for Wigner to measure the state of the same particle? Is it even possible to measure a particle twice? And get different results?

As far as I understand, the wave function collapses and the superposition doesn't exist because the measurement is made. The wave function is just describing the probability of possible states and once the measurement is made the state is known. To say that the superposition still exists to Wigner because he didn't take a measurement nullifies the fact that Alice did already make a measurement? 

I tried reading the link @ChrLzs provided and it's definitely above my pay grade.

The main problem I'm having is relating the actual experiment to the thought experiment.

Thanks for your help.

In the experiment the same particle can 'collapse' more than once. So if ten different people measure it, it can collapse ten times. That's the least hocus pocus way to look at it.

You could also say that there are (e.g.) three particles, acting as one. The shared particle (1), Alice's particle (2) and Wigner's particle (3).

It depends how you prefer to look at it. What makes most sense to you.

 

Edited February 21, 2022 by zep73

[onlookerofmayhem]

6 minutes ago, zep73 said:

It depends how you prefer to look at it. What makes most sense to you.

Thanks. I'm going to have to look into it a lot more to understand it.

[zep73]

29 minutes ago, onlookerofmayhem said:

Thanks. I'm going to have to look into it a lot more to understand it.

I forgot to mention the problem with multiple 'collapses'. You see, under certain circumstances, the same measurement can give two different results. Which supports the 'three particles acting as one' explanation.
Typical QM. You think you found a way to demystify it, and then it does sh!t like that.

 

Edited February 21, 2022 by zep73

[onlookerofmayhem]

8 minutes ago, zep73 said:

I forgot to mention the problem with multiple 'collapses'. You see, under certain circumstances, the same measurement can give two different results. Which supports the 'three particles acting as one' explanation.
Typical QM. You think you found a way to demystify it, and then it does sh!t like that.

 

One of the aspects I know I'm severely lacking is the actual measurement aspect.

Like how a singular particle can be isolated and measured in the first place. And even then be measured multiple times within the same parameters.

QM is most definitely mystifying! Tough to parse out the relevant details. 

[ChrLzs]

3 hours ago, onlookerofmayhem said:

One of the aspects I know I'm severely lacking is the actual measurement aspect.

Like how a singular particle can be isolated and measured in the first place. And even then be measured multiple times within the same parameters.

EXACTLY!!!!!  This.. definitely this.

Where is the step by step description, in detail, of what they do and why?  Every time I see this 'explained', it seems the experimenters get very shy about how they went about the process, and (of course) what assumptions, and logic, was applied.  Also, I note that the claimants say that up until now, the process couldn't be done and recent advances now allow it, but again, no explanation of what that means and what the advances actually were.

In this case, like I said above, they talk about 2 distinct 'realities', but they continually use the word "representing" instead of actually explaining what the process was.  If someone here can walk us through it, I'd be greatly appreciative... but I won't promise to not ask tricky questions!