What is Einstein's Equivalence Principle?

111,953

5,968 0

Published 2020-08-01

To check out the physics courses that I mentioned (many of which are free!) and to support this channel, go to brilliant.org/Sabine/ and create your Brilliant account. The first 200 will get 20% off the annual premium subscription.

In this video I explain what the equivalence principle is, how it connects special relativity with general relativity, and why it's got nothing to do with the idea that the earth is flat.

A good starting point for the reference that I mention at 7:39 is this paper:

Nonequivalence of equivalence principles
Eolo Di Casola, Stefano Liberati, Sebastiano Sonego
Am. J. Phys. 83, 39 (2015)
aapt.scitation.org/doi/10.1119/1.4895342

All Comments (21)

@davidasher22 3 years ago

I was a Flat Earther for 4 years.... and then I turned 5..
@daveseddon5227 3 years ago

6:41 "which is, excuse me, a sphere" Nicely summed up Sabine!
@parthabanerjee1234 3 years ago

"The flat-earthers think........." - There is already a paradox in that incomplete sentence.
@mrroneill99 3 years ago

It must be quite exhausting being a heroine fighting the demons of ignorance and intentional deception. But you do it beautifully! ❤️👼👍🏻👌✨🇮🇪☘️
@oisnowy5368 3 years ago

I wonder how many brain cells Sabine had to sacrifice just to read the flat earth website and think about what they wrote. Hope the hurt's gone away by now.
@MultiAstig25 3 years ago

She explains and throw shades with casual sassiness. I love it!
@booJay 3 years ago

Really looking forward to your live stream on PBS Space Time next week, Sabine!
@ddmurley 3 years ago

Sabine makes Saturdays extra special
@uvofsam 3 years ago

I just found your channel today, i am literally binge watching every video of you and also sharing it with my colleagues of my university. Thanks for this great videos
@DavidSaintloth 3 years ago

" the Earth is, excuse me, a sphere. " LoL, love it.
@LoneIgadzra 3 years ago

I never cease to be impressed by the graphic design of these videos. The costume + background combo is always super-effective at keeping my focus long enough to digest the concept.
@christianmartinez4858 3 years ago

It's 4:14 a.m. here, but I'm glad I'm investing my time into the things I love, and I'm good at it. Physics is the best, and I'm happy channels like this exist in these moments.
@GRosa 3 years ago

"The Flat Earth Society has members all around the globe." 😎
@AmanGupta-sj1rx 3 years ago

These channel is just great😍🔥
@jimsweeney7339 3 years ago

I have to say watching your videos is a highlight of my week. You have a remarkable ability to take a complex topic, break it down and explain the concepts in 8 - 10 minutes. It is a talent that many do not have, well done and please keep it up.
@filipgren6091 3 years ago

I'm in love with popular science for long. Your style is refreshing. Keen and precise. No fantasy, just facts. Refreshing.
@colfrancis9725 3 years ago

Thanks, great video and Merry Christmas to you. At 5:52 you stated "all kinds of energy densities (....) gravitate". Did you mean ALL kinds? Does gravitational potential energy count as a form of energy that gravitates? Do we need to calculate and include gravitational binding energies as a contribution to the stress-energy tensor? Can we calculate that binding energy BEFORE you have the stress-energy tensor to tell you how spacetime curves?
@AChicShowBigganPodcast 3 years ago

most remarkable collection of nonsense xD
@g.v.3493 3 years ago

Thank you for this video! I was confused since a time when some of my physicist friends told me about the elevator illustration of the equivalence principle and I devised two thought experiments that could distinguish gravity from acceleration in a closed box. That can’t be done with a localized point particle, however. Your videos always help!
@artspam 3 years ago

congrats on 100.000 subscribers!