David Kaplan. I will remember his name and seek out more of his lectures. He's clear and concise and a very engaging speaker. The question and answer portion was particularly good.

This lecture gave a clarity about particle physics . David Kaplan is a real scientist who honestly says " we do not know" and takes a failure as challenge and new possibilities. Thanks to PSW to provide this full event on KZfaq. By the way who are those 73 persons who are giving low thumb?

Wonderful talk. A huge thank you to Prof David Kaplan for helping to make what is a difficult topic accessible. For anyone stumbling upon this talk, I do highly recommend it. I will avoid commenting on some of the audience questions. David demonstrated a universe-sized trait of patience with some inquiries. 🤭

I wish my Q.M. course had been taught by Dr Kaplan. The problem being that he's younger than I. Weinberg's "Dreams of a Final Theory" is very good.

Mr. Kaplan is extremely knowledgeable and very enjoyable.

Great lecturer! Perfect balance of analogies, theory, math and touching the fringes of human knowledge and a good dose of speculation. Loved it!

Thanks for sharing your lecture.

Great lecture! I've been following the series and enjoying it quite a bit! Thank you for providing these very tolerant professionals!😅

I agree, I endlessly watch lectures on the same subjects and this is one of my fav as well!

I have watched a hundred or more lectures on this subject this was one of the best

Wonderfully honest and entertaining presentation. His recommendation of Weinberg's popular book was spot on.

At around 1:00:00 Dr. Kaplan discusses our outlook on dark matter as a means to explain why galaxy rotations tend to be similar throughout the entire disc of the galaxy. Since rotation curves flatten at larger distances, have we ruled out the potential that *a black hole can cause a physical compression of distance so that, effectively, there is a hidden radius of sufficiently substantial quantity at the center of the galaxy that is not accounted for* and, if it were to be, would provide a sort of cushion of distance between the central object and the inner disc of the galaxy to make the inner and outer disc of similar actual distance from the center of the galaxy? As it stands today, if the edges appear at 1 light year and 10,000 lightyears from the center, but there is really a hidden distance of 100,000 light years, then the edges are truly 100,001 and 110,000 lightyears away and thus would have much more uniform results. To be fair, *we literally use trigonometry to measure the diameter of a galaxy, and a star's position outward, and so any such warping of actual distance would not have been accounted for.* Perhaps the gravitational well described by Einstein is from every angle inward having such a well, where vast distances can become hidden. To me, if dark matter truly existed, and was the cause of the observations, it would be detected in ways beyond gravitationally. For it to exist, we have to describe it as non-interactive in all ways except to conveniently explain gravitational observations. We have managed to find other observations we cannot explain that we have attached "dark matter" as the cause to give it more credence. But. Likely, there is indeed a hidden distance within the central region that is causing galaxy rotation curve discrepancies between prediction and observation.

Excellent, top notch lecture! The Q&A is also gold.

He brought us to the edge of knowledge here, and to the limits of language, revealing questions that are still unanswered, and verbal analogies that are still inadequate. It makes one feel primitive...

Highly enjoyable and credibly informing. Thanks for the overview!

1:37:41 A question from a non-physicist and a very good answer.

I really enjoyed this one. He is a great speaker.

I especially liked the explanation of atoms as 'waves' as a mathematical (not linguistic) description. The limits of our language when it comes to scientific explanation causes confusion.

What a good lecture! So most of the ‘nothing’ (romantic word for stuff we don’t know about) is dark matter as far as our physio-perspective is concerned. My gut feeling is that it doesn’t belong to physics but to something resembling physics.

Marvelous information.

Brilliant

Great Q&A session.

Good Lecture !

Awesome lecture.

True teacher

His pointer goes at the speed of light

phenomenal talk, Eric Weinstein.