The EPR Paradox - Ask a Spaceman!

let's talk about the epr Paradox and I've noticed that most discussions of the epr Paradox and the APR arguments kind of miss the Mark here and I'm not going to blame anyone for misrepresenting the epr Paradox the epr paper because the epr paper itself is like really really poorly written it's not the greatest paper in the history of science even though it is I believe the most highly cited paper in all of physics now epr stands for Einstein Podolski Rosen so this is Einstein working with a couple collaborators after he moved to Princeton to escape the Nazi regime in Germany and the reason it's not very well written Einstein was a great science writer he was an excellent Communicator he had such Clarity of arguments like every paper he wrote was boom boom boom you can follow it it's great but for this particular paper he wanted it to be written in English he was a he was in Princeton after all and he didn't believe that his own English was up to Snuff for writing the technical details of a paper so he left it to his two collaborators podolsky and Rosen to write it and then as soon as it was published he admitted in a letter to Schrodinger that yeah I let them write it because English is their first language it's not mine but I don't really like how the paper came out and I would have written it differently if if I could have written it in German but that's that's the way it is here's here's the epr Paradox and the story that the epr paper tells um I'll tell you that story and then I'll tell you what Einstein was actually trying to get at so the epr Paradox looked at the phenomenon of entanglement where you take two Quantum particles you bring them close together you let them get all intimate close to each other you know they know each other go on a few dates and then you separate them when you separate them these two particles now share a single Quantum State a single wave function that describes both particles simultaneously so you can't describe one or the other independently anymore they are now linked entities in the cosmos what happens to one effects in a in a very broad sense what happens to the other in measurements on one give you instant instantaneous information about the other because they share a single unified State regardless of distance so Einstein said let's state two particles let's bring them together let's entangle them and then let's separate them now I'm going to take this particle let's call particle a and I'm going to very precisely measure its position knowing its position because these particles are now entangled I now also know the position of the second particle because that's what entanglement does it gives you information about that distant particle no matter how far away it is and then I'll wait a while now I'm going to measure the momentum of this first particle boom measure the position and then later measure its momentum I can do these because these are separate processes I can measure these as precisely as I want and now I have instantaneous information about particle B the second particle and I know its position and its momentum as accurately as I want which violates the Heisenberg uncertainty principle which tells us that you can't know a particle's position and momentum as tightly as you want as as much as you want to that there's a fundamental limit to measuring those two quantities in tandem but look look I didn't even have to go visit particle 2 it lives in another zip code I didn't even have to call or text it and I was able to get its precise position and momentum in violation of the Heisenberg and certainty principle so in this paper Einstein says either you have to give up the Heisenberg uncertainty principle or you have to give up the idea of entanglement you can't have both good Niels Bohr great physicist took on the task of responding to the epr paper and he wrote a paper a few months later submitted it to the exact same journal and took the very sassy move of using the exact same title which I believe was a can quantum mechanics provide a complete description of nature or something like that use the exact same title so so sassy and basically said well no it's more complicated than that you see when you measure the position of particle a this affects particle a so now it's a new system so that when you go to measure um its momentum later on it's a different particle so so you're not violating the Heisenberg uncertainty principle case closed so on the face of it it looks like Einstein is trying to show a flaw in the Heisenberg uncertainty principle of flaw and quantum mechanics based on the uncertainty principle as I said look I found a way to get out of the Heisenberg uncertainty principle and then on the surface it looks like Bohr is saying oh no no Heisenberg insert new principle it's more complicated than that uh it's fine it's fine it's fine but that wasn't Einstein's point that wasn't what Einstein was going after he wasn't trying to attack the uncertainty principle he was trying to attack entanglement he was trying to point out that quantum mechanics is flawed because it allows non-locality Einstein was saying if you want quantum mechanics speak correct and you want to say the Heisenberg uncertainty principle is true which is a part of the quantum mechanics description of nature then there is a major flaw non-locality I can know instantaneously the properties of this particle no matter how far away it is it could be across the lab it could be across the country it could be in the Andromeda galaxy and somehow I'm able to know about it and influence and affect it because of this Quantum phenomenon of entanglement foreign basically said yeah no non-locality is the thing quantum mechanics is non-local moving on so it looks like bore won because he was able to rescue the Heisenberg uncertainty principles show that there wasn't a violation but that wasn't the point of the epr paper and why it was poorly written because that wasn't Einstein's point he wasn't attacking the Eisenberg uncertainty principle he was attacking entanglement he believed that physics should be local he believed that what happens in the laboratory stays in the laboratory that if I make a measurement or an observation or an experiment on a physical system right in front of me all that should matter is the physical system that's right in front of me that this whole non-locality thing of quantum mechanics where two particles influence each other across vast distances instantaneously violated everything else we know about physics because all other physical laws are fully local Einstein set his career on developing local laws of physics and he said it violates even common sense if I run an experiment and I get a result if physics is local if what happens inside of my experimental apparatus or everyday experience only depends on what I can control in the experiment and I can control the experiment I can know the outcome I can make predictions I can do science but if there's this weird non-local entanglement throughout the Universe and like an electron in the Andromeda galaxy farts and then somehow that influences the experimental result that I'm gonna get well how can I trust my experimental result how can I trust physics itself how can I get anything done if the universe is non-local Einstein said this was crazy and he used the epr Paradox to show that quantum mechanics was the insane and he wasn't buying it and that it was missing something and Bohr basically said yeah it's crazy bud what are you gonna do about it but Einstein's main objections stood it does appear that quantum mechanics is non-local we see it all the time we have experimental verification of the non-locality of quantum mechanics Einstein never liked this he believed until his dying breath that quantum mechanics was incomplete in that the appearance of non-locality the appearance of entanglement was the number one dysfunction of this Theory since then we've simply grown used to it even though we can't explain how it works thank you so much for watching please like share and subscribe and go to patreon.com pmsutter to keep supporting this show

Channel: Dr. Paul M. Sutter

Views: 11,246

Keywords: space, cosmos, universe, astronomy, physics, astrophysics, cosmology, science, quantum mechanics, epr paradox, einstein

Id: NImTluj5w6Q

Length: 9min 21sec (561 seconds)

Published: Wed Nov 23 2022