8:09 This is actually the reason storm clouds flatten when they reach the top of the troposphere. Where the stratosphere begins (troposphere ends), the air temperature starts to climb, and this temperature inversion means that moist buoyant masses of air lose their buoyancy because the air mass is no longer less dense than the surrounding air. So it flattens out.

“It looks like a cluster of nerds!” - Diana describing her fan base.

It's not called the Death Zone because people just die there. It's called that because your body doesn't recover anymore, so you just get continually more fatigued, even when resting. So that's why people without O2 try to keep the time at the top as short as possible.

"Speed Dating in a Hypoxic Chamber" - what a great idea for a new Netflix reality-show competition !

Dianna I just wanna tell you how grateful and thankful I am that my 13 year old (almost 14 😬) daughter has someone like you that she looks up to. We watch your videos together and you're an amazing role model. She asked me to buy us matching "I love physics" shirts for her bday and we can't wait to get them in. As a parent I try to share with them my love for science but it gets harder the older they get. My son (10) also loves your channel and wants you to be his science teacher. 😊 Thank you for making physics fun and entertaining for people of all ages.

Loved this!

Your videos get better and better every time! This one was crazy professional and incredibly well done. Keep on going for it! Looking great as always.

I just love the way Dianna interacts with people and asks basically all the necessary questions about the design and risks involved

Heyy happy teachers day Dianna , u are an amazing teacher , I have never learned so much physics in my school that I leaned with u .. thankyou for teaching me so much , have a great day ..happy physicsing 😊

I thought it was the coolest thing when I saw you talking with David about pressure on his channel the other day. I was like, I know that PhysicsGirl!

Just discovering your channel now, but I love it! You rock! I never took any major courses in physics, but am fascinated by flight, laminar flow, thermodynamics, pressure and more! :)

In the death-zone there is enough oxygen, but the partial-pressure-difference of oxygen between air and blood is too low, so too less oxygen is diffused to the blood.

It’s kinda like the movie “Up”.

This was really informative and interesting! Great job explanation of what is going on. Amazing job, as always!

I'm so happy you not only got to be there. but got to interact and talk to him. Congrats!!!!! So much fun.

I was super excited - possibly more than I should have been - to see you that morning. You were brilliant! There was also a huge missed opportunity though not including Destin (of Smarter Every Day fame) in the ordeal, and his experience and subsequent video on hypoxia. It was a great choice too to have MKBHD host.

I watched this and was so happy when you made your appearance. I haven't heard anything about them bringing the cluster down. I know they had measures in place to pop balloons and give it a controlled descent but I think it would be interesting to hear how that went for them.

What a great conversation, and background on this stunt. Now I need to find the David Blaine video, cause I’ve seen it in my feed, but had not been super keen to watch it until now.

I watched the live stream of the Ascension yesterday. It was awesome how much thought and teamwork went into the event.

Absolutely loved the surprise (for me) you were also involved physicsing about with "from another lane David" .. Ur presence there made me feel Blaine is more human than originally conceptualized. Keep it up girl !

When you said 15,000 ft 5:19, it shows 15,0000 ft whatever 4 zeros after it is called.

5:15 hmmmm........ 15,0000 ft you say?

I enjoyed watching this video. Nice job. I hope you have a hopeful Monday, Dianna!!! ❤️🙏🏻

Great coverage and discussion Diana! Thanks!

SHERPAS are not ordinary human beings.

This reminds me of the MythBusters episode when they were testing whether it was possible for a kid to accidentally get carried away by a bunch of balloons. Based on their results and the enormous engineering effort of David's team, it looks like it takes more than just a few mates and a tank of helium... Fun to think about though!

What a great video! A nice “behind the scenes” with a generous amount of science.

Amazing content as usual Dianne. Thanks

diane: *talking about how air pressure and oxygen levels affect the human body* me: I wonder if I can fit that balloon through my front door?

Sherpa's can survive because of generations of mutations with their red blood cells which has adapted.

I'd learnt about the high altitude conditions watching U2 and SR planes/pilots documentaries; your channel goes more in depth that those use to go.

I wish I had seen this video BEFORE I caught the event live. I don't even remember how or why I had tuned in live, I think someone shared a link or something so I watched out of curiosity. But it's interesting to see how much went into something as *seemingly* simple as: rising into the air on balloons and skydiving back to Earth.

The only negative thing about this is the waste of Helium. Which is in short supply.

Oh my... lol. David, Sherpas don’t live up above 26k. They travel up there and back down to their homes. These trips often include several days of acclimating and safety stops. Also, they have generations of experience living and working at high altitudes, through which, their bodies have had subtle changes. It’s not an equal comparison to say that your average person can survive there, especially if traveling from near sea level in a period of hours. Also, death wouldn’t occur instantaneously, nor is it equivalent to drowning. Rather, it’s an altitude at which people are increasingly likely to experience death, likely over a period of minutes. Of course, he is a magician and entertainer, so I trust this is all for show and he will be fine. But please don’t spread misinformation! You could hurt someone.

Hey dayna you videos are very cool and informative I really like it a lot and I have seen all the videos its awesome

You are amazing. Thanks for these videos.

Thank you so much for introducing me to the real Physics out of the class room. Happy teacher's day ♥️♥️

Really cool! When the physics girl approves it, there's not much to add.

Another great episode! consider doing one on his levitation trick

Wow. This is so cool! You are so fun and awesome. What a great collaboration!

In collaboration with KZfaq, the event was streamed live. He was carried up to 24,900 feet -- or about 4.7 miles by 52 helium balloons,before skydiving and parachuting back to the ground.

5:40 The moment Dianna got COVID from David Blaine XD

8:26: 2 million feet, while still in the atmosphere (sorta), is not only above the Armstrong line, and the Karman Line (meaning, it's space), it's higher up than the international space-station

It was a great surprise seeing you and Marques there!

You make me want to be a physicist. I love your passion for physics 💕. It's contagious.

Dang I was really hoping to start a speed dating place 30,000 feet in the air

really pleased David Blaine had Physics girl on their what He achieved was Incredible and to watch it every Step of the way was also Incredible

That was awesome. I must actually still watch the full video. It is on KZfaq, but it is like 3 hours long....

Physics Girl, Knowing David Blaine, Its a magic trick. He never went up..... He was always on the ground during the stunt lol...

What the fock? I waited the whole video for him to actually fly. lmao

Dianne is so cool and down to earth when I see her smile in a video I involuntarily smile back 😁

I didn't even see who posted the video, I just saw cluster balloons and clicked. When I saw you speaking I was like "I know her!" lol. Your "it was nice knowing you" face was priceless when he was saying he thinks he can go that high without oxygen.

It was nerve racking when he was putting his parachute on for some reason...

Physics Girl, since helium is a limited resource and we need it for really cool science like CERN and LIGO isn’t this stunt with all the testing simply a waste? For a vanity project?

I'm curious about whether they took into account the additional tension on the balloon surface from the friction of balloon-to-balloon contact. Under all that load, with the expansion forces due to pressure and as the balloons expand their starting positions relative to each other are going to be different which will probably add a fair amount of strain on the surface.

Best one yet ! I love it !

Another big danger is, the balloons failing while you’re high enough to die from the fall, but not high enough for the parachute to fully open before impact. 😬

he had a harness that was attached and just pretended to use one hand to look cool.

Great video! Always been a big fan of David Blaine, now I watch can watch science and magic at the same time!

Your video part in Ascension was great

It's just riding a regular helium-filled balloon in a basket but without the basket. Kind of a lame stunt.

WTF moment: 2:18 "Because he won't be wearing it [his parachute] as he's ascending." So where TF is he going to get it from? Thin air? [I haven't watched further yet.]

Very cool! I actually live in Tulare, not far from porterville and I didn’t even know about this going on!

One thing I like about Diana is that she never tries to be the center of attention like many youtubers do (or most commenters for that matter).

"It is safe to say that no one is getting up to 2 million feet in a cluster of baloons" David Blane: "Hold my baloon!"

9:40 air baloons with explosives attached yikes, i dont wanna fly that ship

In a previous life (job) I and my coworkers had the opportunity to go to the South Pole. The SP station is on top of a continental glacier so the "ground" level is about 9100ft. Added to that the atmosphere being thinner at the poles the pressure altitude ranged from 10000ft to 12000ft depending on the weather. When I first started there one of my coworkers told me about when he had a watch that gave altitude based on barometric pressure. He said that is was oddly funny on the airplane during approach when the cabin's pressure was adjusted from the 8000ft flight pressure to the ground pressure his watch would register an ascension unlike any other flight he took where the watch registered a descension.

Love your work physics girl. Keep bringin it on! Marty- oz

Dianne excellent video, clean clear facts! David could take a leaf out of your modest book!!😉

You can spot the "evening star" Venus right besides the moon at 2:33

You really seemed more passionate and excited about this than usual!!!

Physics Girl, your enthusiasm is contagious 😀🎈🎈🎈🎈😃

Interesting Physics Girl👌🏼

since it's magic, he probably never left the ground.

Great video !

The purging breath is a lot like the pursed lip breathing I learned in pulmonary rehab (I have COPD) so building backpressure like that by exhaling through a small mouth opening can help keep your airways full and get more oxygen from the air you have before you let it out.

Well *This could actually revolutionize air travel*

HAPPY TEACHERS' DAY MAM 🎉🎉🎉🙏 RESPECT from me!🔥🔥 Mam I had a question, could you please explain it. In normal circumstances, when we throw a ball at suppose 'v' velocity then the ball comes at us with '-v' velocity, that means, at a certain point the velocity of the ball is zero. Zero Velocity!! So if we apply this to REFLECTION of LIGHT! we can say the photon just before bouncing off the surface of the surface comes to a zero Velocity point as we see in the graph. So at that point photon is at rest and thus it is at massless situation? Anyway, mam happy teachers day, love and respect❤️🙏 from me.

David , is a fearless human also inspiring personality I truly respect him a lot. God Bless!!

for the first 5 minutes i thought this video was from a year ago, just realized it's from September 4th 2020, 2 years ago! wow it's been so long!

I WAS HERE! and I learned the physics of magic (and enjoyed)

I wish David would redo it but this time when there are clouds so that he would go through clouds.

Great video! Pilot here so I want to point out that it's far more accurate when you refer to specific types of altitudes rather than just the altitude above mean sea level whether its pressure altitude, actual altitude(True Altitude) or density altitude. True altitude above sea level, in this case(and most cases), is of little importance since pressure changes all the time so TRUE altitude where you pass out and experience hypoxia(which is not mentioned in the video) and die is different on different days. it could be +- 500 ft or even up to 2000ft if you're in Siberia where they usually have high pressures. That means if you were to die at 25,000ft of True Altitude in Hawaii you'd die at 27,000ft of True Altitude in Siberia. If the pressures were even lower in Hawaii then the gap would be even higher. Not a lot of people seem to understand the concept of altitudes so would be good to see you put out something related to that!

Why was this actually better than his own livestream? Production quality and everything, this could have easily turned it into a discovery channel special.

David: I'm gooooing to tha DeaThZoNe Me: Bruh, pleeeease STaaaaAaaHp

Blaine is such a liar I can even listen to this whole video

this is a great video. better than the official one created by the David Blaine camp. Great job. thanks for sharing. Why didn't he wear the parachute from the start?

Dianna does a wonderful job of summarizing the the whole project which was 3 hrs long.

You seem to have added one zero to many at 5:20

love the graphics...but why the beanie and fireplace??

Sherpas do survive on Mount Everest without oxygen but they have acclimatised over many years as they live at high altitudes. Climbers have to acclimatise over weeks before they go to the top so you can’t just do this over a period of hours

This was really awesome! David is a cool guy!

I'm a minute in, and wondering why they're not wearing face masks...

where was everyone's mask? was this before the pandemic? i'm so confused

She is the perfect one to interview David. I see the chemistry

you should look at «with life at stake (med livet som innsats)» of Andreas Wahl. He is a norwegian physicist who has tried something similar.

"feet", really?? how about metric system?

Feets, fahrenheits, pounds, i didn't understand anything! please use the international system...

Great video! Thanks 😎

I hiked many 14'ers and never experienced any issues with the altitude, even while exerting myself. I was a resident of CO at the time, and that may have helped. But the idea that some are able to manage higher altitudes without artificial support, even into the 'death zone', is not surprising.