#5minphysics 

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.

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

"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".

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

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

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).

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.

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

Lawrence, you are a legend

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

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.

Didn't know cows had atmospheres... xD

Thank you for doing these videos.

What an awesome thought!! I love it!

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!

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

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.

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.

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...

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

That was 10 minutes Sir 😂 but still greatly appreciated 🤍

Et Tu Lawrence!

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 :).

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

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

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

Engineers be like: 4:01

I find the inacuracy of the math disturbing! :(

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

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

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

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

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

who else doesn't know who julius caesar is

cm² x cm = cm³ 😂

recycled dino farts, might explain some climate deniers mindset

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

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.

Yeah but you are breathing his fart too