Session Recording: here.
Mervyn’s Slides: here.
The QUIZ we did together: here.
@manoel In-course search feature on coursera: https://www.classcentral.com/report/coursera-search-within-course/
@sonal we have the decedent of Newton’s apple tree at MIT! I have eaten that apple!
@hhliu Gravitational lens - Wikipedia
@sakshamsrivas2679756 Isn’t the recent picture of black hole like a reddish ring thing
@dhawal https://iopscience.iop.org/article/10.1088/0264-9381/32/6/065001
@hhliu Yes! In 2019 How Scientists Captured the First Image of a Black Hole - Teachable Moments | NASA/JPL Edu
@sakshamsrivas2679756 Don’t they have like a term for it was it spaghettification?
@Fabio Yes Saksham! I don’t know what it means but I guess that what would happen if you get too close to event horizon
@sonal Saksham, watch Shep Dolhman’s TED talk posted on our forum…. Inside the Black Hole Image that made history
@sakshamsrivas2679756 Okay I kinda have a question in the course they said that photons are emitted when energy is absorbed or released in an atom. So like does the electron just become a photon or like how does that work? quanta is like a packet of light photons right? So the energy like becomes the photon.
@Ziggi_747 To move down in levels, it loses energy as it goes to a lower level?
@sakshamsrivas2679756 Duality is application for every matter isn’t it tho. I’m talking about De Broglie hypothesis to be specific.
@hhliu Correspondence principle - Wikipedia
@sakshamsrivas2679756 Yeah isn’t the smallest possible length that makes sense is called plank length?
Does the modern bulbs still work on incandescence? So Like the LED are luminescence right?
@hhliu Luminescence - Wikipedia
@Fabio incandescent: emitting light as a result of being heated.
@hhliu One of my favorite channels on YouTube What Happens at the Event Horizon? | Space Time | PBS Digital Studios - YouTube
@manoel Hammer vs feather on the moon: Hammer vs Feather - Physics on the Moon - YouTube
@hhliu There is debate on when and where spaghettification happens, it’s a misconception that it happens at the event horizon
@sonal Saksham, there is a nice class on courser from Stanford on Special theory of relativity —check it out …! 
https://www.coursera.org/learn/einstein-relativity
@hhliu There’s a controversial new theory about there being a “firewall” at the event horizon Firewall (physics) - Wikipedia
@sakshamsrivas2679756 Okay I have a question can you tell me why anything cannot go faster than light like what physics does anything going faster than breaks
@Shambhavi “Nothing” can go faster than the speed of light. The Big Bang happened faster than the speed of light only because it was the expansion of “Nothing”/space/no material.
@sakshamsrivas2679756 There are like many science fiction films which say that if you go faster than light you can go back in time…So like how true could this be; i mean as you said time stops when you go at the speed of light. I mean if you put a value greater than c in the equation then the denominator would become negative thus making the time dialation negative?
@hhliu Tachyons in fiction - Wikipedia
@nikunjprajapa2672287 A Brief History of Time - Wikipedia — Great resource
@Fabio Sakham, for me I see that time is tied to the quantum movement, so when we move too fast, we deacellerate the quantum movement. So, relatively speaking, we are moving slower the faster we go because the particles are trying to catch up. but if we move faster than light, I don’t see why the particles would go back the same way they came. For me, it sounds like a wild guess or just fun to play with this concept of travelling backwards in time
@hhliu Fascinating new theory about the 3D universe being encoded on the 2D surface or boundary of a black hole’s event horizon The Holographic Universe Explained - YouTube
@Ziggi_747 Isn’t it the amount of energy that you need that limits us to go back in time or faster than time?
@hhliu Holographic principle - Wikipedia
The best tool to understand what (theoretically) happens when you travel faster than light is something called Penrose diagrams (named after Roger Penrose)
This video explains exactly why superluminal travel and travel backwards in time are the same thing
@Shambhavi This book has a chapter which explains the speed of light and how time itself slows down when we try to go faster than the speed of light. It is explained in such a simple way (though comics) that I was able to appreciate the beauty of it even in 9th grade! Albert Einstein and his inflatable universe : Goldsmith, Mike, 1962- : Free Download, Borrow, and Streaming : Internet Archive
@sonal A nice book by Roger Penros — “Road to Reality’ —he received the Nobel prize in physics for his black hole research — Road to Reality is rotten for layman …so, read it, if you like to to read books written by scientists!
@hhliu Physics-QM-Black body radiation – Howthingswork.org
