Mindscape Ask Me Anything, Sean Carroll | February 2021

Out of all the lectures I listen to on youtube, Sean Carroll's voice is most soothing.

I’m listening to your Google talk as this notification came out! Keep up the good work Sean.

My day suddenly got better

Long form answers are so much more satisfying.

I wanted to know your personal opinion on Sir Roger Penrose CCC theory, thank you .

Great point also about the difficulty of a venture being a big reason for why it's worth it. Intellectual endeavor

2:45:30 Light reflected off a mirror doesn't involve absorption and re-emission of light. It's a scattering process. Fluorescence involves the absorption and re-emission, and this has no preferential angle.

Your "jump off a building" comment made my day. I tried it out my front door today 31 times. Sure enough, I didn't fly away... even though my mind wanted to. I must admit my mass/acceleration might need more than 20 cm to acquire flight in any of my engineering programs. Thanks for the lift in attitude rather than altitude. You Rock!

Can you do an episode on the topic of John Wheeler? How did one person manage to attract and support so many highly successful grad students? That plus his own contributions has had a combined impact on the field that is truly awesome.

Love your work keep it up!

I am a computer scientist watching physics because it's interesting, glad to hear a physicist could find my field interesting.

I dont know if you read these, but. I think a lot of people would be extremely interested in a podcast with Demis Hassabis. I think he is different from the other ML guests you have had and id be interested to hear his ideas on ML applications to physics, especially since his goal for ML is to better our scientific knowledge. Of course I dont want to make it seem like i am demanding anything, so only if it seems like something you would be interested in. But he is an expert in neuroscience, AI, and he does have experience interacting with scientists/philosophers. I'd love to see you two brilliant minds interact. Thanks for these great podcasts Sean!

We are at the center of the universe, because since the universe is not expanding into anything, the entire universe is the center of the universe, the same as saying that every point in the universe is the center. Some things are hard to express without circular logic.

I love hearing you tackle philosophical themes. Wish I had a fraction of your intellect.

I personally love the long answers and long podcasts like most people probably do. But the dumb questions are usually entertaining if they are funny and the dumb physics ones really really help people that are trying to learn. Not everybody is a graduate student! I know I have personally learned a ton from questions that many would consider dumb. I'm sure you can parse out the really awful ones unless they're funny. I would say a combination of the top 100 best questions with as long answers as possible would be perfect. Take a few and do them really long and keep the worst ones really short. Thanks for everything!!

Professor Carroll, Thank you for your contribution in popularising all the wonderful concepts modern physics was able to procure. Using the occasion I'd very much like to hear your thoughts about the nature of spacetime. I have always wondered if spacetime itself could be quantized and whether its proper to ask a question "is spacetime an emergent phenomenon of quantum fields existence? Or is it the other way round?" Can you suggest any materials which delve into such topic? What are your thoughts on this matter? In any case - all your work is very much appreciated. Godspeed!

To give another explanation of why time reversal doesn't reverse the direction of forces: Acceleration is the second derivative of position with respect to time d²x/dt². If you change to t'=-t, then you can calculate the new acceleration d²x/dt'² , and we get two minus signs from the chain rule (once for each time we differentiate by t'). So it cancels, and the acceleration is invariant

Thank you

You just totally rock! And I can prove it!!

Are questions submitted in advance? If live, when is the March 2021 edition scheduled for? Thanks