Nima Arkani-Hamed - The End of Spacetime [Resource]

Mainly a resource thread of Video's and Papers on Nima Arkani-Hamed and Friends new theory over the last 5 years...

General introduction

20th June 2008. The union of quantum mechanics and gravity strongly suggests that spacetime as a basic concept is doomed, and there are related indications of fundamental limitations to quantum mechanics in both the early and late universe. In this talk I review these paradoxes and describe indications for a new picture where spacetime and quantum mechanics will be seen to emerge hand in hand from more primitive principles, making contact with new areas of mathematics. I give concrete examples of how these ideas work in the context of scattering amplitudes, describing particle collision experiments of the sort performed at the Large Hadron Collider.

https://www.youtube.com/watch?v=t-C5RubqtRA

16th May 2020 - Zoomplitudes 2020: Nima Arkani-Hamed (IAS)
"Scattering Amplitudes and Clusterhedra in Kinematic Space"

Part 1 of 8
https://www.youtube.com/watch?v=YOzbFeQmwN0

Part 2 of 8
https://www.youtube.com/watch?v=VlD-MPtjoUQ

Part 3 of 8
https://www.youtube.com/watch?v=K-iFHvKn9Jo

Part 4 of 8
https://www.youtube.com/watch?v=1kx4iqHRWCk

Part 5 of 8
https://www.youtube.com/watch?v=PXNotrUMabk

Part 6 of 8
https://www.youtube.com/watch?v=ximpBOD0r1c

Part 7 of 8
https://www.youtube.com/watch?v=xOusuMq83Rg

Part 8 of 8
https://www.youtube.com/watch?v=fomPVtdNYNQ

This short lecture at McGill fits somewhere between the introductory Spacetime is Doomed lecture, and the marathon Zoomplitudes 2020, but adds more explanations for a non-specialist audience.

11th September 2020 - Spacetime, Quantum Mechanics and Positive Geometry at Infinity

https://www.youtube.com/watch?v=INVEggZZ5Ns

In this Christmas Lecture at the Institute for Advanced Studies Princeton, Nima focuses on showing how Time emerges from this new mathematical theory, covering Causal Diamonds and Time evolution...

19th December 2020 - Nima Arkani-Hamed (IAS Princeton) on Spacetime, Quantum Mechanics and Positive Geometry at Infinity

https://www.youtube.com/watch?v=j_LAGoHmHzo

As the old system collapses (I'm still blown away that I'm living through this enormous upheaval and revolution in physics!) Here's a Technical, but simple explanation of the new theory over 5 lectures...

School on Modern Amplitude Methods for Gauge and Gravity Theories
ICTP South American Institute for Fundamental Research
July 24 – August 4, 2023

So what we're looking for is a different question, to which the amplitudes are the answer. In this question we don't want to ever talk about...

1) No interior of spacetime, which means in more down to earth language... No virtual particles, or the on-shell philosophy. And..

2) No Hilbert space - no reference to any of the usual rules of quantum mechanics.

Where does this question live therefore? This question has to live in just the Kinematic space that defines the scattering process. So the amplitude depends on some variables for sure. It depends on the on-shell momenta, the spins or helicities of the particle. But that's it, that's your data. That's our canvas. If we imagine... as we will in these lectures, that we're just dealing with scalar particles... it's just the space of the on-shell momenta of the particles. That's it... N on-shell momenta. Alright? The particles are massless, N massless momenta. That's your space! In the space of N massless momenta, we have to learn to ask a question, who's answer is going to give us scattering amplitudes. OK? And that's our challenge, because this space does not seem like a particularly fertile place to do anything. It seems pretty arid, what are you going to do with the space of N on-shell momenta? Ok? So that's our challenge, alright?

Now what's been happening in this part of the business for the past decade or so, is that we're starting to understand the types of questions we can ask in Kinematic space, whose answers have all the richness and complexity of amplitudes. These are extremely simple questions. So, I want to tell you this thing ahead of time, this is maybe the simplest subject in all of theoretical physics! You could explain what is going on to a... the previous avatar of this story for gluons, or N = 4 super-Yang-Mills, it's the story of the amplituhedron. You could explain everything about the amplituhedron to a bright high school student, they don't even need to know calculus, they just need to know what determinants are. And the story I'm about to tell you could be explained to a bright junior high school student because you don't even need to know what determinants are. You just need to know what vectors are, and how to add vectors. The ideas are incredibly simple! But they are a little bit abstract, and a little bit alien. They are not the ideas that we are normally used to thinking of when you open up a theoretical physics, or physics textbook of any sort.

https://www.youtube.com/watch?v=lJwn4R3PeNc

https://www.youtube.com/watch?v=YozGfYf5wC0

https://www.youtube.com/watch?v=L0fx8TSe46k

https://www.youtube.com/watch?v=Jx2DLPw_sz0

https://www.youtube.com/watch?v=SS_0sVUZYLA