Gertie wrote: ↑July 29th, 2018, 5:10 pm
That doesn't seem to get us very far then, does it? In terms of being able to establish if serial (arrow of time) cause and effect, and independently existing stuff, are mutually exclusive possibilities ?
You mean does my answer prove Bell's theorem. No, it doesn't. I don't know my physics well enough to express exactly why these two principles are mutually exclusive.
And isn't there a deeper issue, to do with defining reality in terms of maths (an abststract desciptor) identified/created by conscious subjects, to describe 'real stuff''? What's the justification for giving maths a stronger claim to reality, than the stuff it's describing?
This is all based on empirical results, not some conclusion drawn from a mathematical abstraction. The theory says that no mathematical abstraction can have both those properties and still be consistent with empirical results.
It seems **** backwards to me. Without stuff, and observations of said stuff, there is no maths. So any maths which asks you to deny the independent existence of stuff seems silly.
But the stuff the observers are talking about isn't independent. They're observing it. It exists to them.
Maths and patterns and information, always have to be about stuff, surely?
No, mathematics is pure, but it can be applied to what we observe. Mathematics I suppose needs an abstracting entity to comprehend it, but 2+2 equals 4 regardless of anything comprehending that, or of the existence of four globs of stuff.
We're in the position, right here right now, of sharing a model of the universe which we've found different ways of describing, including QM. But they're just descriptions, not stuff itself.
Of sharing a model, or a model of the same apple shared between observers? Describing the universe different ways is not really "sharing a model of the universe".
But all that exists can't be maths or QM, because they are mere abstract descriptions of something else - descriptions of stuff doing things. Either/or the describer/the described must exist for descriptions to exist.
Something must exist for something to exist, a tautology I guess. But I don't find objective existence necessary for the apple to stand in relation to me, thus allowing me to experience it. That's a difficult bias to drop, but try as I did, I could not identify what either the describer or the described being 'real' provided except to make the experience real. I'm not a realist, so that doesn't bother me. Even an idealist is a realist of sorts, believing experience to be real, and then failing the same old question of why the idealist happens to be real.
The descriptions might be accurate or inaccurate, or tell us something more about the nature of actual stuff, but they wouldn't exist as descriptions, if there wasn't something to be described.
I'm describing what we experience. That's something. It's just not objective.
Hence relying on maths/QM to tell us whether stuff exists independently of us conscious observers/measurers seems ****-backwards to me. Maths can help us understand the deeper nature (or more granular characteristics) of stuff, but not that its very existence relies on/is interdependent on particular types of description.
A measurement of Earth is taken in July 2118 from a star that is 110 light years away,
'A measurement is taken' means what? I'm never sure. Does it require a conscious observer?
Interpretation dependent. At the raw physics level, it typically means that say the (observed) cat has some causal effect on the measurement system. It can be anything. One interpretation (Wigner, 1981) makes consciousness a cause of wave function collapse, not just a causal interaction between objects. That makes it an interpretation outside of the methodological naturalism upon which modern (post-dark-ages) science is based. It is a supernatural interpretation. The idea has no traction. All the quantum measurements are typically done without conscious observation. The humans just gather stats after thousands of test runs.
Or would the effect of light from a dead star hitting a dead planet causing chemical reactions in rocks count as 'a measurement is taken' if there was no-one there to measure it?
Yes, but it is not a chemical reaction we're after. We want wave function collapse, if your interpretation includes it. Several do not, so there is no measurement role to the physics. An interpretation with locality must have observation be an effect, not a cause of anything. Looking at the moon is not something I do to it, but is something it does to me. Photons have traveled from moon to me when I've observed it.
from a star that is 110 light years away, causing you to collapse into a specific state 10 years ago, and causing your current memory of 2008 to correspond to this defined state that the distant measurement caused. Always interesting to put yourself at the receiving end of a wave function collapse.
Can you explain this some more? An observer on that planet would see me doing stuff in the past, because the lightwaves take time to travel. Are you suggesting that every time I'm observed that has a causal effect on me?
In collapse interpretations, it causes your state to collapse from a state of superposition (a description of multiple states with computable probabilities) to a real state.
If so, wouldn't my experienced life veer radically when I'm in a public place being observed by many people, to when I'm alone? That doesn't seem to be how it works.
No, your state is entangled with that of the nearby public, so they're in superposition with you. Again this is all interpretation dependent, and I'm sort of describing Copenhagen where the observer is distant, just to point out its implications.
Scrodinger's cat is both dead and alive, but the lab assistant inside the box with the cat is entangled, meaning there is both an assistant seeing a live cat and an assistant seeing a dead cat, but no state of seeing both. Opening the box by the outside observer will collapse that state into one or the other, and the assistant that observed the opposite state collapses away.
So let me simplify it to something they've actually observed in the lab. Entangled particle pairs seem to be always have correlated measurements, regardless of separation by distance or time. I correlate two things, move one to the moon, and measure the spin of both simultaneously, they will be +/= or -/+, but never both measured the same. Now I have two sets of such particles in possession of Alice and Bob respectively. Each takes one of the entangled pair and gives it to Victor and then measures the one they keep, but not divulging the result of the measurement. So they've both made an observation now. Later on, Victor decides randomly to take the two particles he's been given (still unmeasured) and entangle them with each other or not. If he chooses to entangle them, then the measurements already performed by Alice and Bob well before the decision was made will turn out to be correlated, where if Victor chooses not to entangle them, then the measurements taken by Alice and Bob will be random, not correlated. That means (given realism assumptions) that Victors choice seems to have determined what Alice and Bob measured at some time well before Victor's decision was made about how to relate their past measurements.
They've not done this experiment with humans playing the roles of Alice and Bob and Victor since they've not invented a device that can contain the secret held by something complex like a human. It doesn't work if Alice and Bob tell Victor of the results before he makes his decision.
The interpretations with locality interpret that experiment differently so there is no causal effect to past events.
In the context of this thread, my general points would be that -
QM is a way of describing reality, not 'the stuf of reality' itself.
Well, some interpretations say it IS the stuff itself. Nobody has actually ever found stuff, no matter how close they look. What they find instead is a mathematical wave function (which uses imaginary numbers). Some QM interpretations say this function is the actual stuff of reality, and some just say it is a descriptive part of the model or some such. MWI for instance posits that the wave function (and only the wave function) is actually what the universe is.
It seems that reality can be described in different ways at different levels of resolution (classical, quantum and who knows what else we haven't discovered), but there still has to be a reality for it to describe.
Plenty of things describe non-real things, so it just doesn't seem to follow. But hey, most interpretations say there is reality being described by the model. I'm not saying there is no objective reality, just that I don't take it as a given. My favored model describes my reality. It is quite real, just not objectively real.
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