Why Everything You Thought You Knew About Quantum Physics is Different - with Philip Ball

UPDATE: A few of you were asking about the Alice and Bob analogy used in this talk so we asked Phil Bill if he'd be happy to explain it in more detail. He was, so here's the follow up - https://youtu.be/5_0o2fJhtSc

Finally someone that explains quantum mechanics to the popular audience without abusing analogies and making vague claims. I love this guy!

Alice and Bob's relationship..."It's complicated". lol

I watched a young woman give a YouTube lecture 10yrs ago saying the same thing,
"The wave function never collapses it becomes entangled with the measuring equipment".
There is no collapse and never was.

"Nobody understands the Alice and Bob analogy" (Richard Feynman)

26:34 "This Box's blackness is in the box, what would it possibly mean to say this box blackness is also kinda partly in this box" Perfect analogy for understanding the misconception of locality!!

The Blackness itself is an emergent quality of our measurement of it. It can only be measured when the lights are on. The color is tied up in the very properties of light itself... the very thing used to measure the blackness is PARTICIPATING in its very existence. This is because, in our perceptual experience of certain things, we draw borders where none exist. (blackness is not something that can exist on its own but only as a combination of things) Both boxes have the local hidden variable of a suface that interacts with light, but depending upon the light I shine on them, they will reflect a different color to my sensors (eyes).

So we are measuring an aspect of the sensor(eyes) and the intermediary device (light) simultaneously when we say "blackness." (the problem is conception and language)

THAT is what it means to say that the blackness is also kinda partly in the other box and this analogy holds with QM as well. Some qualities are combinations not fully contained within an object and are therefore "nonlocal" in a very non mysterious way.

The real question here, at least to me, seems to be the question of whether quantum mechanics is purely epistemological (that is, it is only a theory about what we know) or does it also contain an ontological (that is, this truly is the nature of the Universe and not merely a product of how we're looking at it) component. Another question that I think needs to be asked is what separates a measurement, such as what we do in a laboratory, from an interaction such as what quantum particles will undergo. Does a quantum particle, when interacting with another quantum particle, go through all the same problems of dealing with probabilities of the values of various properties when determining how to respond to those properties as part of the interaction? For example, electrons A and B undergo a spin-spin interaction with each other. Do they also, like physicists measuring spin in a laboratory, have to suffer through the problem that they each have a 50-50 chance of seeing the spin of the other electron as being up or down relative to some intrinsic orientation relative to the reference frame of a given electron, and then, only after making the "measurement" can it determine how it orients its own spin? However, even as I write the question, I realize there is a fundamental error in the question because it accidentally introduces a classical idea that the electron is definitively in one state or the other, and that's precisely the sort of thing that quantum mechanics says is not happening.

So then, I'm left to ask the question, what exactly is happening when two particles interact? How do those particles resolve their quantum mechanical nature with each other in obtaining a particular set of responses, with various corresponding probabilities, based on the probabilities of allowed values of the various properties that the two particles have and interact on the basis of those properties? Is this interaction the same as one particle somehow measuring the other, or is performing a measurement fundamentally different from quantum interaction? If measurement is a fundamentally different process, then does that not introduce the possibility that quantum mechanics may not be intrinsic to the nature of the Universe but merely a by-product of how we've been observing it?

Schrodinger arrives at the vets to pick up his cat. The vet says, "Well, Mr. Schrodinger, I've got some good news and some bad news..."

Quantum physicist walks into a bar. Bartender says, "Weren't you here tomorrow?"
Quantum physicist says, "No, but I'll be back yesterday."

One reason why Quantum Mechanics is confusing is that explanation often involve the term "particle". This is because we normally think of matter as consisting of objects of some kind. If one (mistakenly) defines a "piece of matter" to be an object that, with sufficient energy, can be broken down into smaller "pieces of matter", e.g. particles, it becomes a recursive never-ending loop that makes no sense intuitively. How could a "piece of matter" be divisible into smaller "pieces of matter" which themselves could be further divisible, and so on, to infinite levels. No. That makes no logical or intuitive sense. Hence, at some level a "piece of matter" can only be divided into something else, something that is not a piece of matter or a particle. In a way, Leucippus and Democritus were right when they said that the atom was indivisible. When smashed, the atom produces not atomic particles but waves. Avoiding the concept of particles in the first place could make Quantum Mechanics much more explainable.

I love this theme and I've been studying about quantum physics by myself for 3 years.. I wish I could make an "university" about.. the course would be phenomenal

Anyone else scratching their heads at the rabbit/dog analogy? I have a feeling there could've been a better example.

Alice, Bob, dog, rabbit and coins - an excellent example of how not to do analogies. Speaking as a huge fan of Dr. Ball.

quantum physics - every time you learn something you realize you dont know shit and now need to learn another 10 things

The punch line i loved ‘“ nature does it best and we need to adjust our expectation”

so basically this guy says:
1. Electrons stay as particles the whole time, they do not change their density into wave like matter.
2. The wave function is merely a mathematical field that tells us a probability in exchange for a position guess.
3.Quantum entanglement is when two particles interact and become linked in a way that can only be explained as becoming one system, not transmitting information between them, but actually being affected as if both of them were at the same place under one quantum system.
4.*not sure if i got this one right*- A measurement does not change reality and affect what is being measured, it simply changes our level of knowledge.. the path of an electron is determined already before measuring, its just that before measuring, the position cant be known for sure by equations.


but in the double slit experiment we can see that electrons are actually waves because of the spread outcome that cannot be attributed to particles. so 1 is not correct. 2 is not correct.
about 3- if thats true (if not then special relativity is wrong) it means that there is a dimension in which these two particles stay together, unaffected by space-time and its laws, maybe a dimension though time in which the past affects the present is ways that make certain past events meaningful, which makes every quantum particle have a memory in a way..
about 4- i have no clue.
Help here?

Thanks Mr Ball for explaining that to me. Thanks for the hard work.

I am quite in a superposition of liking and disliking this talk :-)

Thanks for the upload. Fantastic lecture by Phil Bill whose eloquence and way of speech reminds me of Cicero from Rome (the TV show). Really enjoyed it and felt enlightened.

the last ten mins OMG full on wisdom right there <3