"Research is what i do, when i don't know what to do" I'm currently unemployed watching this at 5am!! love it!!!!

THIS is how you give a lecture. No lip smacking and “uuhh’s”. Well done, concise and understandable. Thankyou!

You are a born lecturer. At last I have stumbled on someone I can listen to learn and understand astronomy.

I feel like I've watched enough videos about black holes by now, but somehow they keep pulling me in.

Like others have said, I hate when I start watching these RI talks late at night. I end up staying up most of the night. I enjoy them that much!

Chris Impey has a gift for conveying information. Granted there's no math here , but the concepts are dealt with in such a way as to make them completely accessible. What a fantastic lecture, and what a fantastic lecturer.

Now I know why time passes so slowly when sitting next to my mother-in-law.

I love how he uses such rare words in almost a nonchalant manner, yet I have to go and google these words to see the intricately layered meaning behind them. Blasé, quiescent.. to name a few. This man is a treasure!

Good luck finding it now but Chris Impey's Essential Astronomy series of lectures is one of the modt fascinating things ive ever seen

Thank you so much for uploading these Videos

fantastic lecture. also, that's the first time I've seen Hawking's grave. what an absolutely perfect, badass tribute - and such a flex, that you're so synonymous with black holes that you get to put one on your headstone.

Fantastic lecture. Thanks Ri

What an amazing lecture! Many thanks for the upload.

Lovely! Thank you for providing this video.

A great lecture - one of those where almost every word went over my head, yet I was still absolutely captivated. Bravo Mr Impey 👏

10^100 years. We had a good run.

This guy is great! I learned several new things about black holes and I've been reading about them for decades.

The best science talk I’ve seen in 50 years.

Wonderful lecture. One of the best yet.

Brilliant. Thank you!

Truly stunning.

This is easily the best lecture I've seen on black holes... and more. I think it's because it's easy to understand!

Fantastic presentation. One of the best I've ever seen.

I need to stop watching these before bed

Fascinating. Thank you.

THE SMOOTHEST EXPLANATION, HE MADE ME UNDERSTAND AS IF I WAS STUDYING NEWTONS FIRST LAW OF MOTION.. CHRIS IS REALLY GREAT. HATS OFF

Amazing talk, I really enjoyed it!

This will be forever one of the most amazing videos on UKposts. The "holy crap" value is completely off the chart!

Fantastic lecture. remarkable!

That lecture was an exceedingly pleasant experience all round.

Easily understood , great lecture.

What an amazing lecture! Thanks for sharing this video, giving me the opportunity to learn a bit more about black holes and it's mysterious properties with a great talk by Chris Impey.

This is a wonderful video. Someone would be hard pressed to describe and explain this subject matter any better.

Impressive lecture! I was just waiting for him to gloss over some key details, yet he literally covered every point from start to finish -- even touching upon nuances like the conservation of angular momentum while the star collapses and the dissipation of Hawking radiation for the black hole to evaporate and the paradox of information loss at the event horizon.

28:00 gave me goosebumps. Absolutely beautiful and humbling

Amazing lecture as always.

great lecture! I have been following Chris for years. He is a pleasure to listen to

excellent. thank you

This man makes listening easy! Great stuff. Thank you.

It was a remarkable speech by chris. And we request please still make like this more speeches about these things

Well done RI, this one was absolutely fantastic.

He's good at explaining things simply

Fantastic information and splendid professor!

It's just my impression or his English is just exquisite

Thanks Chris, great talk. Haven't seen you since Edinburgh, about 1979!

Fascinating lecture...

What a fantastic lecture

I remember attending a RI Christmas science lecture as a kid and seeing myself in the audience on TV, back in the day when TV had 5 channels and being on TV was a big deal lol

Yup another day another black hole video. Who else wishes they could just take off on a space ship and explore the universe?

I never though about how Edinburgh sounds like "Edinbruh". Amazing lecture, too.

That was a very interesting presentation, quite a subtle ride

Amazing presentation! Even exceptional scientist and presenter! Reality of everything in existence, in a nutshell. Wow!

amazing lecture, such natural flow, such deep understanding and passion - bring more of those!

9:35 Would an observer in an expanding building experience the same red-shift and sense of acceleration similar to gravity?

If time is standing still at the event horizon, a black hole could be a violent explosion, going off right now. From outside, it must appear as an almost eternal thing. Why do we imagine black holes as something, that are "doing" anything at all? If time is slowed down to zero, there is no cause and no effect anymore.

"I took a relativity course and it wasn't much fun"?! GR the single most elegant and beautiful theory in all of science.

Good clear explanation. I can see he writes books.

That visual of 20B solar masses made me feel like I got hit by one punchman

Wow, what a nice lecture Sir 🙏

When i first saw the Blackhole picture , it was just a donut ring! .After your elaboration based on Hawkin Radiation simple mathematical formula , it revealed Astrophysicist painstaking hardwork and knowledge sharing . Very good job done !

My brain hurts but that was awesome 👏👏👏

I have a coupe of questions: If gravity spreads outward at the speed of light, can gravity have an effect on a gravitational wave? Graviational lensing couses the light from galaxies behind them to get stronger, could that be the case also with gravity (reffering to the first question that the gravity would have been bent)? And if that is the case would it be possible due to the superpostions of gravitational waves to create a "gravity tsunami"?

When I was studying my undergraduate Astronomy degree at University College London I always remember a lecturer saying in front of the lecture theatre that he didn't think Black Holes actually existed. He told everyone that it was just a blag to secure research money. Hmmm, maybe. We all need employment, right?

Excellent presentation--clear and interesting for a non-physicist

I have an idea about how black holes work, which seems to be a straightforward consequence of all the relevant theories in physics, but I’ve never saw it being explained in a such way, so I might be wrong. Did I miss something? Here is the idea: Matter falling into the black hole NEVER reaches its center, it doesn’t accumulate in a single point, but it is frozen i to the surface. To explain it, let’s review how matter falls into the black hole from 2 different point of view: POV of an outside observer: An object falls towards the event horizont. But since the object’s clock slows down in the presence of strong gravitational field, we see this falling object slowing down as it is getting close, and effectively freezing on the event horizont (which we don’t literally see, because light doesn’t escape there). POV of the falling object: Our internal clock has constant speed, so we don’t experience any slowdown, so we keep falling through the event horizont towards the center. Or do we? Our time slows down from outer perspective, so the outside world’s time speeds up from our perspective. The entire life of the universe is happening in fast forward, before we are even getting fully throuh the event horizont. In infinite time, we would reach the center eventually, but black holes doesn’t live forever. It evaprates through Hawking radiation, so basically just as we reach the event horizont, we evaporate back to space skipping zillions of years, while the universe is dying around us. So basically we are frozen into the surface of the black hole throughout the entire life of the black hole, until it is evaporated. However since we add mass to the black hole, it also gots a bit bigger by our mass, and the event horizont moves out. And that’s how information is encoded into the black hole. Every particle, which has ever fallen into it, just adds a new layer to it, and the particle is encoded into that layer, until that layer evaporates. Does that sound right?

Excellent, a good lecture, rather than a bunch of big words and advertising.

Man, that animation of the stars boomeranging around the center of the Milky Way was special, thanks.

Wow...this is awesome

25.56 implies the information is lost to the external viewer in relation to viewing from the outside of the horizon. But the information is not lost to the observer relative to the information. Relativity doesn't disappear at the horizon. Just because an observer would be spagettified doesn't break the rules.. the observer would be frozen in time to outside observers but would see the information .. the socks falling across the horizon with his self... In his timeframe.... No paradox.. just not easy to visualize.

17:00m The Oppenheimer/Snyder paper on black holes was published the day WW2 started for Europe (9/1/39). It was well before the US entry into the war and the Manhattan Project.

What a terrific teacher.

This is the first time I really understood evaporation from a black hole. There has always been a voice in the back of my head that said that the number of escaping virtual particles should be 50/50 and I didn't understand the asymmetry. When he explicitly mentioned mass OR energy loss it clicked that an anti-particle that escapes from its pair could hit a real particle and some of the energy from that interaction could be radiated away.

What would be a better lecture would be discussion of all the failures in the math and physics when it comes to black holes

A Brit with an American accent, nice!

Incredible lecture. 10/10

Brilliant video!

Just finished watching this, going outside to make mud pies.

24:40 i thought that all the socks lost in our washing machines are contributing to the dark matter 😎

This was a truly enjoyable lecture

I did Prof. Impey's Astronomy MOOC (very good, BTW). IT's interesting to see him in this different context.

Exactly these concepts that produced my PhD in astrophysics a long time ago. And you don't have to wait for the end to use BH as energy sources. Close to the horizon they act like one-way time machines, sitting there for a while will propel you into the far future after the cultural marxists are long gone.

I volunteer to be catapulted into Sag A*. Not sure how I report back (leave that detail for the boffins) but the offer is on the table 👍 Let me know asap before I get another cat or some other type of pet please.

Nice video. Very informative.

I must get that scifi book of this gentleman. The ending of this lecture is so deep and hopeful.

Imagine a day when you walk into wallmart, and right next to the Toaster and Microwave ovens; is a small Black Hole Generator, which has a small red warning label on it saying, not suitable for children or people who want to cause the world to end.

Einstein's ER=EPR limit worm hole at Planck's scale l=gm/c^2 by entanglement.

Really interesting talk!

Brilliantly give lecture

@35:54 XKCD! Actually... almost all the videos in this presentation are from various free internet sources, including youtube.

What would be the implications if we'd absolutely fail to measure 1) Hawking-Radiation, only Unruh 2) Unruh-Radiation, only Hawking 3) Both instead of just one of the two? Not only by starting from the premise that we'd use today's top-notch knowledge, tech, materials etc. but also assuming that even if we got more advanced technology (some bordering on new physics/Science Fiction) which would enable us to directly observe a Black Hole like a space probe/spaceship equipped with a Fusion-Drive capable of reaching 0.5c or more (Time Dilation kicks in), Warp-Drive or even a Wormhole-Observatory (whatever you can imagine) we'd fail to observe 1, 2 or 3? ps: the methods mentioned above just serve as plot-devices no matter if possible or not, it's about the implications of my question and a "What If?" Scenario

I'm only halfway through and had to start up my pc to write this. He seems to have perfected the intellect of a brit with the subtle bluntness of an american scientist living in the south. What a great listen this is

What a fantastic lecture and lecturer. 👨‍🏫

Who thought the music during the visual aids was a good idea?

i can kinda still hear the brit in his voice

Terrific !!

A particularly good one !

We have only a googol. Hmm... Better make it count then.

Well done.

Beautiful

he said if you watched your friend fall into a black hole you would never see him go inside the black hole because of time running infinitely slow ...does that mean you can come back 10 years later and still see your friend not go past the event horizon.