#5minphysics

[@naturediary7651]

The fact that you are personally taking your time to make these videos and sharing them with us, trying to estimate our gratitude in 'order of magnitude' is incalculable! Thanks again Lawrence.

[@GEMSofGOD_com]

It takes 20 minutes, man. It brings so much more back to Laurence and everyone, so why not.

[@jacobbond9796]

Wow, it is so "simple", yet so remarkable! And makes you think. Beautiful lectures. All the best prof. Krauss.

[@scientificnirvana1009]

Happy to know I have shared atoms in my breath with Hitch.

[@woody7652]

Enjoy the weather and thank you very much. Cheers, Lawrence!

[@bigzy666]

These videos are very much appreciated, sir. You didn’t have to make the effort as you have more immediate and more important concerns. But thank you very much for your time and effort. It takes a lot of skill to be able to communicate big ideas to small brains

[@ShadowZZZ]

Cool. But there are a few problems here: 1) In order to approximately calculate the air of the atmosphere, you want the volume. So you have a bigger and a smaller sphere, where the smaller ones has the radius of the earth and the bigger one R + h meaning radius of the earth plus the height where the atmosphere ends. Then you subtract the smaller from the bigger volume to get to the volume of the atmosphere: V = 4/3 *π*(R-r) 2) It only is true if you assume that the atoms of the exhale of a person really get evenly spread into the atmosphere. But it is much more probable that the atoms follow a meterological wind current or stay stationary near to the exhaler. 3) Even if all of these abstract assumptions are granted - its still kind of meaningless, because I could say that every time you take a breath, you inhale a molecule that hitler or literally anyone else you can think of exhaled. A molecule is a molecule and every chemist will tell you there is no essential difference in the material properties between two O2 or N2 molecules. Let me be the first one to dislike this video. I'm really not impressed by this meme-thought that Krauss has probably repeated telling dozens of times.

[@vk6uu]

At about the age of 10, I discovered the fun in mathematics. How many seconds in a day, a year etc. How long in days and hours is a million seconds. Would tell my parents what I had calculated and the usual comment was that's interesting. Mathematics is a lot of fun. Thanks Lawrence.

[@Ohotoho]

"Yeah 4*pi is about 10" had me in tears :D It also reminded me of a smbc comic (saturday morning breakfast cereal) where a teacher is asked how she remembers pi and she says "I just look at my hand. It has 5 fingers, and that's about right".

[@niccisherwood1550]

I wish all people knew this, the fact that we all have stardust in our bodies that came from something so powerful (supernova) still amazes me, and that most of my body is many billions of years old (well the atoms at least).

[@michaela9849]

What an awesome thought!! I love it!

[@jameshyatte7230]

Thank you for doing these videos.

[@unverozkol]

Lawrence, you are a legend

[@DuoSocio]

I remember the lecture you did using orders of magnitude to come up with the number of piano tuners in a city

[@jhanna14]

Thank you for explaining this! I guess this applies to every cup of water you drink principle too except we drink less water than air that we breathe.

[@justinasbei]

Physics does allow you to "lean on it". Just go to the nearest bridge and jump a few times to confirm its stable. Thanks professor Krauss!

[@sammyfromsydney]

As always thank you for your video. While that is a wonderful demonstration of "back of the envelope" calculation, what you then should do is check all your assumptions. Some of the things you've ignored here that may mean that it's not true that we're breathing in the same molecules as every person on earth who ever lived include assumptions of: 1. A closed system with no CO2 molecules captured and locked up by plants or O2 released. 2. A constant thickness for the atmosphere, when in fact we know it gets thinner very quickly. 3. Uniform mixing over I think you said 50 years. The point is that orders of magnitude estimate and back of the envelope calculations are a good quick and dirty first estimate, but basing your actions on them may mean you make big mistakes.

[@lkrauss1]

sure... I don't think you make big mistakes, you make mistakes that are at most off by an order of magnitude unless, as you indicate, the assumptions are off by more than this.. but as I understand it, the actual mixing and recycling time for and average O2 molecule in the atmosphere has been estimated and it is about a century, so this is not that bad...

[@sammyfromsydney]

@@lkrauss1 if your assumption about mixing, CO2 capture or the size of the system is off it is possible you are so off (several orders) that you can't assume you are breathing in molecules from every dead person. Don't get me wrong. I like what you have done and the thought is uplifting but as we are talking science truth matters more than what we want to believe. There are sufficient things that are wonderful about the universe that it won't matter if a few of our favourites don't hold up. None of this takes away from your wonderful demonstration of the technique. Nothing but thumbs up from me.

[@jacobgonzales28]

Both of you are probably right and wrong. Syousef is probably right about oxygen not hanging around that long. Yet, Nitrogen probably does, and since 80% is nitrogen, you can be pretty sure that you are inhaling the same nitrogen that lots of interesting people have.

[@das250250]

@5:45- 5:55 not square cm.. cm³ or cubic cm

[@FirstLast-le6io]

Didn't know cows had atmospheres... xD

[@user-sl5nm9js8p]

Because of the air compression in the balloon, perhaps a plastic bag could provide us better visual estimate about our lungs capacity ;). It is also probable that I was just breathing oxygen or nitrogen atoms that were in your lungs or Albert Einstein's ;). What a great thought!!! LOL, I came up to the same idea as you did before I've reached to 08:57 :).

[@_John_Sean_Walker]

Andrew... When you have an empty milk box, you can flatten it and blow it up again. Can you blow up two?

[@user-sl5nm9js8p]

@@_John_Sean_Walker no I can't. I am not able to drink two milk containers a day, sorry 😉. But, to be serious, average adult Male lungs capacity is about 6 litres. I've never seen milk box that big. However, tidal volume is just about 0.5 litre so it might work in this case. But this case only. Anyways, this is great science.

[@_John_Sean_Walker]

🎈

[@user-sl5nm9js8p]

🍼🧃

[@1333ao]

Hey my dude one thing here (from a chem teacher) at STP there are 6.02x10^23 molecules or atoms in 22.4L of gas. For your estimation you are using 1L, so on order of magnitudes you may be off by 10x for 1L. I know its a rough calculation but Julius Ceaser didnt just breath in just oxygen for sure he breathed in about 80% of nitrogen as we do today. So maybe your estimate is better for oxygen rather than just total number of particles... Not sure if thats what you were going for but let me know if off here...

[@lkrauss1]

in fact that is why I divided 200 by 10 at the end, to get a range from 20-200... because of the fact you mentioned.

[@Saitama62181]

Excellent, but shouldn't volume be expressed as centimeters cubed?

[@lkrauss1]

cubic centimers is centimeters cubed.

[@Saitama62181]

@@lkrauss1 But you accidentally wrote and said the volume of the atmosphere in square centimeters / centimeters squared. Sorry to nitpick. Time stamp 5:40

[@lkrauss1]

@@Saitama62181 oops.. :)

[@Saitama62181]

@@lkrauss1 :-)

[@davidroach8277]

The famous balloon with galaxy's on...😂...sorry had to stop and start again after that.👍

[@nikitaelizarov7444]

You don't need a smaller notebook, Dr Krauss, you need a bigger easel.

[@vk6uu]

A thought. How often do you breath your own breath from say 10 years ago?

[@lkrauss1]

it all depends on mixing, but assuming your house is reasonably insulated, you are breathing atoms from you own breath all the time.

[@scientificnirvana1009]

Et Tu Lawrence!

[@najlamuhammad2099]

That was 10 minutes Sir 😂 but still greatly appreciated 🤍

[@apburner1]

There are approx 6*10^23 molecules in 22.4 liters of a gas, not 1 liter.

[@ShadowZZZ]

Engineers be like: 4:01

[@lordnilsson1]

When 5 min. are equal to 10 min,... physics is really hard.. ha.... ha...

[@MelliaBoomBot]

9m10. Its Arvid *Högbom*. Don;t google *Hugbun* like I did...tho tempting on so many levels.

[@vrzalm]

I find the inacuracy of the math disturbing! :(

[@_John_Sean_Walker]

cm² x cm = cm³ 😂

[@stephenkamenar]

who else doesn't know who julius caesar is

[@dorukeke8665]

With all due respect, the title should be 2 I think

[@lkrauss1]

yes.. but within an order of magnitude, they agree. :)

[@dorukeke8665]

@@lkrauss1 😄 By the way, I've been watching and following you for 4 years now, and you are my inspiration to become a physicist. I'm 18 now and this Fall I will hopefully start my higher education in physics.

[@lkrauss1]

@@dorukeke8665 Thanks.. Good luck in your studies! I hope it all works out.

[@GregNow]

After watching this I was left with the thought that Adolf H. breath saying "Scheiße" When Russians entered the Berlin is now in me... :/

[@Seekthetruth3000]

Physics is simple if you understand the math behind it. IMHO.

[@feynman6625]

Again with the simplicity of physics...yeah. That’s a myth. When physicists get mystical...a sign of decadence, they begin to talk about how simple things are.

[@joshua3171]

recycled dino farts, might explain some climate deniers mindset

[@astroboy3002]

Yeah but you are breathing his fart too