EPR Paradox: EASY Quantum Mechanics VISUALISED, Why Einstein HATED Spooky Action At A Distance

The EPR Paradox was the supposed contradictions of quantum mechanics against supposedly reasonable assumptions about our universe - locality and realism.

Hey everyone, I'm back with a new video! This is the first in a two-part series on The EPR Paradox, Einstein's distaste of Quantum Theory, and Bell's Theorem - which eventually showed that he was incorrect about his understanding of the universe, at least in part.

Let's begin with some timestamps:

0:00 - Introduction
0:38 - Einstein's Contribution to Quantum Theory
1:03 - Einstein Doesn't Like Where Quantum Mechanics is Going...
2:29 - The Assumptions That Brought About the EPR Paradox - Local Realism
3:06 - Big Thanks to Skillshare for Sponsoring This Video!
4:03 - Quantum Entanglement - Einstein's Getting Annoyed Now!
5:39 - Realism is Really Important (to EPR)
6:30 - Is Consciousness Really That Important to Quantum Mechanics?
7:11 - EPR's Reasoning as to Why Quantum Theory Must Be Wrong
7:54 - How To Measure Spin in Different Directions
9:16 - Two Explanations for Reality
9:37 - Hidden Variable Theories Suggested by EPR
10:53 - Thanks for Watching! Check out My Socials :)

Einstein, Podolsky, and Rosen got together to write a paper. In this paper, they showed that an entangled system in quantum mechanics appears to break both locality and realism / determinism, two assumptions that were seemingly very reasonable to make for our universe.

Locality is the idea that communication between two points in space is limited to the speed of light, as information needs to be passed from one point in space to another - and the fastest this can happen is at the speed of light.

Realism / determinism is the idea that if we know everything about a system, then we can predict precisely how it looks at a later point in time.

A simple entangled state (later known as one of the Bell States) was studied by EPR in their paper. They showed that making a measurement on one particle in this entangled system resulted in an instantaneous collapse of the other particle into a known state - even if the two particles were very far apart - according to quantum mechanics.

This broke locality, because the second particle did not have enough time for light to get to it, after the measurement was made on the first particle.

It also defied realism because before the measurement was made, quantum mechanics suggested that the system was in a superposition of all possible measurement results, and collapsed into one such upon measurement. This happened with a certain amount of randomness according to quantum mechanics, which meant that we COULD NOT exactly predict what a system would look like after the measurement even though we knew everything about the system beforehand.

Einstein believed this was all wrong. He hated the "spooky action at a distance" (going against locality), and also said that "God does not play dice" (meaning the world must be deterministic, not probabilistic). EPR suggested another mechanism for how entangled particles may behave.

They suggested a hidden variable theory. This is the idea that the system contains something that we cannot access - a hidden variable. This hidden variable tells the system what result to give when a measurement is made at a certain time on the system. This didn't solve locality, but certainly did obey realism.

In this video, I also briefly discussed the importance of consciousness in the quantum world. It is a difficult topic to understand, and is very easily taken in to the realm of pseudoscience - so I recommend being careful with this idea.

In the next video in this series, we will discuss how John Bell came up with his famous theorem that showed local hidden variable theories cannot be a good description for our universe.

Thanks so much for watching! Please like and subscribe, and hit that bell button too.

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This video was sponsored by Skillshare

[skylineuk]

It should be noted that Albert was the one who noticed that quantum entanglement could occur due to quantum theory and also that he did not disagree with the theory but believed that there was something not probabilistic underpinning it (he believed it was “incomplete”. That is what bugged him). Also some models of quantum theory (many worlds etc.) do not oppose EPR. Personally I’m happier to think things are probabilistic as the alternative is we are just on a set course already planned out for us.

[Jehannum]

At 9:29 I think your coefficients are off. (1/4)^2 is not 1/2. They should be sqrt(1/2).

[sagaa]

Great stuff Parth. I want audiobooks in your voice now.

[koushikchintalapudi]

I heard this word " EPR PARADOX "
in the movie AVENGERS:END GAME
Where Tony tells to Steve while giving him his shield before creating the quantum time machine
Which explains why Lang turns a baby

[rosarionapoli]

What about the second part? I couldn't find it!

[NicolaiNita]

Funny title "Easy quantum mechanics..." 🤣

[aygunatesoglu]

@parth Thanks for the video, as simple as possible but not simpler )))

[akshatnerella]

Hello Parth,
Big fan of yours. You inspired me in having whole new approaches to science. I went into deep thoughts and I have several theories about the way Space-time works and the expansion of the universe involving Dark matter. The problem is that I don't know the math involved, since I am only a high school student. Also, I do not know how to publish a scientific paper. I was willing if you could listen to my theories and help me with the Math, if you think my assumptions are valid and consistent with science. I will be waiting to hear from you.

[nathaliebopp]

Nice video. Bur where is the second part? I just can't find it, which ist very frustrating!

[sunithasomalingam]

Einstein cartoon is Of Course humourous..

But your Hairstyle is better now..😎

Good Explanation..
Always Support ur Content 🙂

[rationallion]

Please create a series of videos called "We're Not Going To Go Into That Right Now" and go into those topics....
Spin up or Spin down would be a fantastic first video. Thanks!

[dk]

"Yes, that guy, again." - S Hossenfelder

[adamjondo]

Where's Part 2 (Bell's theorem') ?

[theartofmusic]

I have watched your video before I go to school now and now I am going to school have a good day Parth
Kisses from Cyprus

[riadhalrabeh]

The reason why spin entanglement is easier than others is because spin is more difficult to destroy by external interactions- hence the persistence of vortices in fluids for a very long time before being destroyed by external interactions or internal loss of energy by friction. regards.

[riadhalrabeh]

There is a simple explanation to entanglement. It is conservation of momentum. It is impossible to move a mass to one direction without moving an equivalent to the opposite direction at the same time. This applies to everything as small as an electron and also to photons and at any distance across the universe. This is also the basis of the Mach principle of distant masses, which is entanglement. Any two entangled particles will remain so for ever till they meet other particles to entangle with and destroy/decohere the first or to be precise get superimposed on it. That is the whole universe is a superposition of pairs of entangled particles.
Einstein locality is still preserved as energy can't travel instantaneously as it involves space and time variables and thus includes motion. So while you know the state of the entangled pair, changing this with time involves energy or radiation that can only move at the speed of light. regards.

[larrybecker]

I couldn't find the link to Part 2. Can someone provide the link? Thanks.

[prashanthramg]

9:56 - if the measurement axis is orthogonal to spin direction, measurement device can't detect anything. Only if the alignment is just a bit less than 90, it would say spin-up and if it's little over 90, it would say spin-down. There's nothing strange about 50:50. Strangeness are the 2 facts (i) when you measure along an axis, spin direction aligns to that (ii) corresponding entangled electron which is not subject to measurement aligns similarly

[siliconvalleyceo]

Yeah, your voice in an audio book will awesome

[Wannabetolkien]

Hi Bro ! How are you? Why have you removed the “How to Cambridge “ playlist?