How do black holes destroy information and why is that a problem?

This video is to answer a question that many of you asked about my video on quantum gravity, which is just how do black holes destroy information and what's the problem with that.
To explain what is the problem, I first introduce the two major concepts in contemporary physics theories, which is the "state" of a system and the "evolution equation". I explain the difference between time-reversibility and time-reversal invariance, and that there are no fundamental evolution equations which are irreversible. The only fundamentally irreversible process we know of is the measurement in quantum mechanics.
Black hole evaporation, however, seems to be fundamentally irreversible, already before a measurement is being made. This is the very problem, because that makes black hole evaporation incompatible with quantum theory.
Support me on Patreon: / sabine

[@DrFuzzyFace]

Sabine Hossenfelder joins Sean Carroll and Brian Greene in becoming a great educator of physics. Where she distinguishes herself is her uncanny ability to take what are arguably abstruse subjects and concepts and explain them with unequalled clarity and economy. My hope is that countless others will discover her powerful and disciplined intellect and polished communication skills, thus allowing them to better understand our physical reality at a quantum level.

[@waynemcnab9496]

I have listened to many teachers, and I have taught a great deal, although, not on this subject. You are a great teacher. Thank you!

[@katg-gk5ox]

My eyes popped at

[@kzeich]

Thank you for not explaining these topics like we're idiots- for not dumbing them down like other educators tend to do- for acknowledging you're speaking to educated people with considerable interest in what you're presenting. Love the platform.

[@wolfgang757]

"Information" is never at a loss when this scientist posts a video! Clear and well presented and I have never seen better on the topic.

[@jbghumanjr]

Wonderful exposition. And that pant suit... is everything!

[@sphericalharmony1603]

That was certainly the clearest explanation of this problem that I've ever heard.

[@averylawton5802]

I think the most beneficial quality of the way in which you explain physics in your videos is you understand the confusion that Layman would have with the terminology and explain it plainly without sounding condescending or demeaning you validate the normal person's difficulty wrapping their mind around such a complex subject that most people spend their lives dedicated to. It's not an easy feat and I have my hat off to you for it

[@docholiday8029]

The mark of a good teacher is the ability to take complex info and concepts and make them easy to understand.

[@thefaboo]

Thank you!

[@alechorn1109]

I have an undergraduate degree in physics from the 1960’s and then became a lawyer so I know just enough to appreciate how much I don’t know. I try to keep up over the years but fail greatly. This presenter is the best physics educator I have know. I always want to run away and tell everyone I meet what I just learned. Thank you.

[@aaroncurtis8545]

I recently discovered your channel. Good stuff content wise, and compliments to whoever is composing these shots and backgrounds.

[@theway5258]

Hi Sabine! Thanks for your life time to teach us all. Your videos are great and clarify our mind and do the world better as i hope. Please keep working on it so we have the gift of knowledge to make things better together. ❤️

[@mountainhobo]

Very clever thumbnail with "42" going up in smoke.

[@claytyler-nt4rt]

Just about the finest, prettiest, most understandable physicist I could ever imagine.

[@robertkelly5025]

Thank you so much for this! I am an middle aged man that has been asking about this for decades but have never gotten a good answer. You, Don Lincoln, Arvin Ash and a few others make life make sense. And, of course, Richard Feynman.

[@iandavidson1]

Such a clear explanation of a difficult subject, such an itelligent person. Thank you.

[@MrKyle700]

Very clear, concise, to the point, easily understandable by a laymen. Thank u

[@anhi399]

I've watched so many science education videos on KZbin, and yours was the first to talk about either "State of the System" or "Evolution Equations". Describing those two elements first gave me the aha moment when you talked about how information can't be preserved. Thanks for the video, here's another sub!

[@peterh.1521]

Sabine gives us an easy-to-understand explanation of something that normally is difficult to understand, since black holes in space are invisible. Thank you for your illustrative videos!