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Message: <blockquote data-quote="Rigsby" data-source="post: 1248110" data-attributes="member: 7361">There are a few variations of the Double Slit experiment and some taking what that finds a bit further again. See:<a href="https://en.wikipedia.org/wiki/Quantum_eraser_experiment" target="_blank">https://en.wikipedia.org/wiki/Quantum_eraser_experiment</a><a href="https://en.wikipedia.org/wiki/Wheeler%27s_delayed-choice_experiment" target="_blank">https://en.wikipedia.org/wiki/Wheeler's_delayed-choice_experiment</a><a href="https://en.wikipedia.org/wiki/Delayed-choice_quantum_eraser" target="_blank">https://en.wikipedia.org/wiki/Delayed-choice_quantum_eraser</a>An excerpt from the last link there: a last-minute decision made on Earth on how to observe a photon could alter a decision made millions or even billions of years ago.While delayed-choice experiments have confirmed the seeming ability of measurements made on photons in the present to alter events occurring in the past, this requires a non-standard view of quantum mechanics. If a photon in flight is interpreted as being in a so-called "superposition of states", i.e. if it is interpreted as something that has the potentiality to manifest as a particle or wave, but during its time in flight is neither, then there is no time paradox. This is the standard view, and recent experiments have supported it.My bold here is key.The main sticking point here with all of these experiments is the fact that they can mimic retro-causality, that is to say that events in the future can actually change events in the past. Now, people have a real problem with that. So they are looking to see if that is actually the case or if there may be something else at play.Enter the emerging field of causal modeling and the work of Chaves I alluded to earlier. <a href="https://www.quantamagazine.org/closed-loophole-confirms-the-unreality-of-the-quantum-world-20180725/" target="_blank">https://www.quantamagazine.org/closed-loophole-confirms-the-unreality-of-the-quantum-world-20180725/</a>This is the most important link in all of this discussion. And this is the experiment he did that supports the experiments that Valentine linked to.Wheeler was espousing the view that elementary quantum phenomena are not real until observed, a philosophical position called anti-realism. He even designed an experiment to show that if you hold on to realism — in which quantum objects such as photons always have definite, intrinsic properties, a position that encapsulates a more classical view of reality — then one is forced to concede that the future can influence the past. Given the absurdity of backward time-travel, Wheeler’s experiment became an argument for anti-realism at the level of the quantum.You can't have it both ways. Either events in the future can influence events in the past or photons do not have definite intrinsic properties when not being observed.I.e. there is no such thing as objective reality. See the last paragraph of this image - [img=700x500]<a href="https://d2r55xnwy6nx47.cloudfront.net/uploads/2018/07/DelayedChoiceExperiment_560-891x1720.jpg[/img]" target="_blank">https://d2r55xnwy6nx47.cloudfront.net/uploads/2018/07/DelayedChoiceExperiment_560-891x1720.jpg[/img]</a>In the classical way of thinking, it’s as if the photon went back in time and changed its character from particle to wave.Original image: <a href="https://d2r55xnwy6nx47.cloudfront.net/uploads/2018/07/DelayedChoiceExperiment_560-891x1720.jpg" target="_blank">https://d2r55xnwy6nx47.cloudfront.net/uploads/2018/07/DelayedChoiceExperiment_560-891x1720.jpg</a>One way to avoid such retro-causality is to deny the photon any intrinsic reality and argue that the photon becomes real only upon measurement. That way, there is nothing to undo.Such anti-realism, which is often associated with the Copenhagen interpretation of quantum mechanics, took a theoretical knock with Chaves’s work, at least in the context of this experiment. His team wanted to explain counterintuitive aspects of quantum mechanics using a new set of ideas called causal modeling, which has grown in popularity in the past decade,Causal modeling, which prohibits backward time travel, ensures that the experimenter’s choice cannot influence the past intrinsic state of the photon.With this setup in place, Chaves’s team came up with a way to distinguish between a classical causal model and quantum mechanics. Say the first phase shift can take one of three values, and the second one of two values. That makes six possible experimental settings in total. They calculated what they expected to see for each of these six settings. And this from Valentine's link:The breakthrough that Proietti and co have made is to carry this out. “In a state-of-the-art 6-photon experiment, we realize this extended Wigner’s friend scenario,” they say.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.Mmm. Six. Back to the Chaves experiment.For Wiseman, the debate over Copenhagen versus de Broglie-Bohm in the context of the delayed-choice experiment is far from settled. “So in Copenhagen, there is no strange inversion of time precisely because we have no right to say anything about the photon’s past,” he wrote in an email. “In de Broglie-Bohm there is a reality independent of our knowledge, but there is no problem as there is no inversion — there is a unique causal (forward in time) description of everything. ”Either time can flow backwards and influence past events because there is an objective reality we can call out. Classical view.Or time does not flow backwards because there is no such thing as objective reality. Quantum view. Anti-reality. Wheeler's view. And corroborating the results of the experiment that Valentine posted. There is no objective reality.In theoretical physics, quantum nonlocality is a characteristic of some measurements made at a microscopic level that contradict the assumptions of local realism found in classical mechanics. Despite consideration of hidden variables as a possible resolution of this contradiction, some aspects of entangled quantum states have been demonstrated irreproducible by any local hidden variable theory. These hidden variable were exactly what Chaves found and proved in his experiment.If the results continue to support Wheeler’s original argument, then “it gives us yet another reason to say that wave-particle duality is not going to be explained away by some classical physics explanation,” Kaiser said. “The range of conceptual alternatives to quantum mechanics has again been shrunk, been pushed back into a corner. That’s really what we are after.”I'm totally out of my depth here. Given the absurdity of backward time-travel, Wheeler’s experiment became an argument for anti-realism at the level of the quantumSo you can have backward time-travel and objective reality (reality as we think we know it). But it breaks too many fundamental laws (not least second law of thermodynamics).Or you can have no backward time-travel, but with NO objective reality (anti-reality). Reality does exist, but with hidden variables, that we can never know and only ever conjure in to existence when we observe them. This maintains entropy (second law of thermodynamics). What a choice!I've probably made a load of mistakes. Feel free to point them out. I'm not clever enough to understand this shit when it comes down to it, but I like to give it a go now and again.And don't forget those pesky Russians thad did travel back in time. I haven't. <a href="https://www.dailymail.co.uk/sciencetech/article-6800577/Move-Doctor-Scientists-time-machine.html" target="_blank">https://www.dailymail.co.uk/sciencetech/article-6800577/Move-Doctor-Scientists-time-machine.html</a>Move over Doctor Who: 'Time machine' created in Russia moves tiny particles a fraction of a second into the past= Russian physicists have effectively achieved the same principle of time travel = They loosely described it as moving in the opposite direction of 'time's arrow' = The researchers worked with electrons in the realm of quantum mechanics= Broken pool balls were able to re-order themselves into their original formationThe Second Law of Thermodynamics deals with transition of energy within a system from usable to unusable.It is the reason our phones and laptops need to be charged, and that our sun will one day die out.It states that energy cannot repeat in an infinite loop within a closed system, and so we must replenish what is lost.The Second Law profoundly sets the limits for what is possible in our universe, defining why everything within it must one day decay.Just when you think you've figured it all out, those bloody Russians come along and piss in your toybox!Either retrocausality exists or it does not!Either man went to the moon or he did not!Either there is life out there in the wider universe or there is not!It's binary. And whether it ends up being a '0' or a '1' "in reality" - then it's pretty mind-blowing all the same.Where the fuck is Bill Nye (your mom's a guy) when you need him eh?Science motherfuckers! Do you even speak it?</blockquote>

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