Has quantum mechanics proved that reality does not exist?

In the past years you may have seen headlines claiming that objective reality does not exist because some quantum mechanics experiment has shown it. In this video I explain what this is all about and why this experiment doesn't show that reality doesn't exist.

Here are some of the articles I am commenting on:

0:00 Intro
0:51 Wigner's friend
5:03 The Extended Wigner's Friend Scenario
8:18 The experiment that shows reality doesn't exist
9:12 What does it mean?
10:04 Sponsor message

[scottmanley]

I smile every time I hear that Quantum mechanics isn't rocket science... if it were I might have got better grades in my QM exams at University.

[JaySmith]

"This isn't rocket science" made me laugh. The rocket scientists are meanwhile shaking heads at the intern staring down the barrel of a turbo-encabulator whilst murmuring "this isn't quantum physics".

[jonwesick]

"Some of my best friends are photons, too."

[Sophie-and-Ken]

The problem with math is that it’s assuming a left right condition upon measurement, but if you can’t measure the thing you are looking it takes on a third state of not existing and it’s the third state the equation can not account for. It’s like the cat in the box problem, what if we can’t see the cat in the box? It’s not dead or alive it just can’t be measured, that doesn’t mean it doesn’t exist.

[nigeltooby]

"... some of my best friends are photons too." Priceless. 🤣

[chrisalvino]

Most underrated part of this video is how clearly and succinctly you defined entangled particles in just a couple of sentences in a way that removes ALL ambiguity about what entanglement actually means. It's not spooky action at a distance, or communication happening faster than light. It's just a shared property, we just don't know which particle has what property until we look

[Quargos]

Honestly, this hits one of the things that I've always struggled with about trying to understand Quantum Mechanics as a causual observer.
Nothing I've ever seen had had a straight answer about what constitutes a "measurement", and how, if at all, the collapse of the wave-function is any different to simply an update of information about a probabalistic system.

[__Ryan_]

She’s so good at explaining this stuff. I may never understand the mathematics behind this but the theories, and these videos are very interesting and entertaining.

[mosesexodus]

*_"Historically, internal inconsistencies have been the major cause of theory-led breakthroughs in the foundations of Physics ... So, we are onto something here."_* --- Sabine Hossenfelder

[ArchilochusOfParos]

One of my favorite channels. Sabine is a gift.

[petewright]

She says, early on, that the conclusion that "reality doesn't exist is patently absurd". This is NOT the statement of a true scientist! This possibility needs to be considered and proved wrong, not dismissed as absurd.

[VincentGroenewold]

I love that conclusion, great explanation of the entire proces.

[somethingsinlife]

Alot of misunderstanding is from the fact that QM has to use Probability because that's the best tool we have so far. It's not because we know exactly what's going on.

[jamesrockybullin]

"... and when I find that theory, that will be the breakthrough of the century."

I hope you do Sabine, I hope you do!

[selocan]

I love how rocket science is keeping its place as the norm of difficulty. Maybe some rocket scientist out there is using the phrase "Well, actually rocket science is not a rocket science" indicating it math/physics basis is not so hard to understand :)

[ralphacosta]

Listening to Sabine is really relaxing-information transferred in a simple, yet thorough manner without hype. Thank you.

[johnclifford]

Quantum mechanics proves that I don't have a firm grasp on reality in general.

[earlgrey]

My Stepdad worked as a physics professor at the top 4 university in the world and he taught quantum mechanics his entire life. A very intelligent man who dedicated his entire life to this subject. And now in retirement he told me with a defeated smile that he still doesn't even understand 10% of it because the subject is so complex that for most of us an entire lifetime is not enough to get to a point where you truly understand it.

So when anyone uses quantum mechanics in an argument i usually just stop listening. Because if you're not one of the handful of geniuses in the world who really understand that stuff.. you are most likely going to misinterpret the data and arrive at the wrong conclusions.

[rlhugh]

Veritasium presents an interesting idea: we ourselves are wavefunctions, in a super position. So, when we make an observation, it's not so much that the wavefunction 'collapses', it's that our wavefunction becomes entangled with that of the system we are observing. Then there are many possible states, and those are all in fact simultaneously present. However, of course, from our own 'point of view', we only ourselves experience one single one of those possible states of the entangled wavefunction. Hence, the wavefunction appears to collapse, but it's more that the observed wavefunction becomes entangled with our own wavefunction. Our brain is in a super-position of states. In each possible state, our brain experiences a different observation, and is convinced that the wavefunction 'collapsed', but there are many other states in the superposition, where our brain saw a different state.

[ParadoxProblems]

It seems that a large portion of this paradox comes from the assumption that we can separate the information about the Friend perceiving the collapse of the wave function (according to themself) from the information about what state it collapsed into.