How many particles in the Universe? - Numberphile

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More links & stuff in full description below ↓↓↓
This video features Dr Tony Padilla from the University of Nottingham.
Extra bit from this video: • Particles (extra bit) ...
See more of Tony talking physics on Sixty Symbols: / sixtysymbols
Planck: sci.esa.int/planck/
Numberphile is supported by the Mathematical Sciences Research Institute (MSRI): bit.ly/MSRINumberphile
We are also supported by Science Sandbox, a Simons Foundation initiative dedicated to engaging everyone with the process of science.
NUMBERPHILE
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Notes from Tony on this video:
1. The numbers I use are based on Planck 2013 data. Data from the 2015 release exists but I chose the 2013 data since the precise calculation of the size of the universe has only been done explicitly in that case as per this paper: www.isaacpub.org/images/PaperP...
2. Near the start I say I’m only considering fundamental particles with mass, and not, say, photons. Actually, I don’t count neutrinos either since they too are relativistic, and the precise results are model dependent to an extent.
3 (later addendum). Well done to anyone who spotted the fact that the 75:25% split between H and He ought to be by mass, and not by number of atoms, as in the video. I realised this mistake lying in bed on the night the video was released and kicked myself repeatedly! Very annoying. Anyway, correcting for this, we see that there actually ought to be 12 H atoms for each He atom, since the atom mass of He is 4, and the total atomic mass of 12 H atoms is 12=3x4. Following the same sort of logic as in the video, we find that there are 62=12x4+14 particles for 16=12+4 baryons. Thats means we should have multiplied by 62/16 rather than 26/7, and so our result should be corrected by a factor of 1.04, yielding closer to 3.4 x 10^80 particles. [Of course, no-one really worries about factors of 1.04 in cosmology :)]. The time to the "apocalyptic” end mentioned later in the video then changes by 3 to 4 years, which is anyway well within the rounding errors of the calculation.

[@numberphile]

Thanks to Skillshare - 2 free months here: www.skl.sh/Numberphile The drone lessons I mentioned are here: www.skillshare.com/classes/Introduction-to-Aerial-Videography-Creative-Direction-for-Drone-Filming/1023605416

[@natsudragnir4131]

Numberphile Please More videos with Terence tao

[@AH-nc6vv]

I'm reading that 90% of the universe's atoms are Hydrogen, not 75%?

[@CCRLH85]

With a density that low, it'd float in AIR.

[@simonkrekels]

Cannibeans Where are you reading this? 75% is quite accurate

[@sansamman4619]

Numberphile, that means that if you put the observable universe in water it would float!!

[@TheMixter123]

All I'm getting from this is that the universe could float in water.

[@Eliina552]

Science Emoji maybe it does

[@YouTubalcaine]

The universe turned me into a newt!

[@Maltanx]

Science Emoji it could even float on simple air, just like a balloon filled with helium

[@bluekeybo]

Nax FM so it's probably floating already, and there's a ground somewhere under it we don't know about

[@formelekandscreen]

Saturn could also float in water

[@mvmlego1212]

Somewhere between 11 and Graham's number.

[@FodderMoosie]

Approximately.

[@mueezadam8438]

mvmlego1212 100% true omg!

[@user-mz7cn9hq8v]

An underrated reference

[@mvmlego1212]

@@user-mz7cn9hq8v -- Underrated? I'll take 130 likes any day, man. Thanks, though. (^.^)

[@user-mz7cn9hq8v]

@@mvmlego1212 look at "there are at least 12" and [a quote from the video] comments

[@MysteryDark01]

Numberphile - the only channel making 9:57 min videos in 2017

[@GarySims]

LOL, no it isn't. You should check out my Bluetooth 5 video, it was over 15 minutes!

[@MC_Grenada]

Gary Sims sorry but you don't understand his comment

[@GarySims]

Hmmm... I guess not then... What did I miss?

[@GarySims]

As a follow-up, if it because Numberphile shouldn't be making such long videos, I get that, that is why I posted about my Bluetooth 5 video as I don't think we should be dumbing things down. Knowledge is power and if something is worth explaining then do it properly.

[@kangawallapuss]

It's because most youtubers aim for 10 minute + vids if they can because youtube favours sharing them and therefore more views, more yt money

[@papa515]

This does (of course) illustrate perfectly just how crazy is it so assume that something that looks exponential now will/can continue so.

[@AlanKlughammer]

Hence the issues with our economy...

[@Phelan666]

Hence the issue with African aid.

[@googolplexbyte]

Digitise Humans to sustain population growth.

[@cavalrycome]

@googolplexbyte - It's not obvious to me that you could represent a human body as data without the storage medium used to encode it consisting of at least the same number of particles.

[@IceMetalPunk]

Compression algorithms are great. You can store lots of information in less space than the original by finding patterns and representing those patterns concisely rather than representing every bit of the original information.

[@TheLeiZurc]

There are at least 12.

[@HINRG14]

TheLeiZurc Correct

[@igNights77]

As a mathematician, I believe you pretty much nailed it.

[@pietruszajka1998]

But less than a google plex

[@V1C.T0R]

+pietruszajka pl *googolplex.

[@Stefkostov]

well you're not wrong

[@kantodream9714]

Only 8600 years ?! Omg this is the most amazing thing I have ever heard. Thank you !

[@yahccs1]

If the growth rate is a constant you can go back in time and see how far back we would have been one small town of 1000 people... or a lot less! It's not as long ago as we think?! The population didn't use to double every 40ish years it took more like between 150-200 years before the industrial revolution, so if every 200 years in the past the population halves say starting with 2 billion in about 1925AD and going backwards it goes below 1000 by 2275BC. If it halves every 150 years this takes it back to 1225BC. If it used to take 500 years to double, we would have been less than a thousand in around 8575BC. It makes no sense to go forward or bakwards with a constant exponential growth rate. The further back you go the longer it must have taken for the population to double (or halve if going backwards!)- until it was a very small population and they had room to spread out and multiply and have a population explosion until they reached a sort of natural equlibrium or very slow growth or phases of growth and decline (before industry and modern medicine started changing things)

[@tomonetruth]

@@yahccs1 You could probably come up with a (slightly) more meaningful value by using the average growth rate since humans appeared. I can't be bothered to work it out, though. 8,600 will do me as a fun bit of trivia.

[@JanSanono]

This is particularly about particles

[@alkatron768]

you sir, are a smart person. Don't let anyone ever say otherwise

[@wade8537]

aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH i see what you did there

[@JanSanono]

172 likes!?!?! I should have a party-cle!!

[@Milesco]

I guess you could say that a Planck is made out of Particle board.

[@JanSanono]

Captain Quirk that's boarderline disgraceful

[@nicholassoucy9446]

A fun little extender we can do with this calculation: So this is assuming humans are practically godlike and can use all the available particles in the universe. However, this is not the case. Due to the rate of expansion of the universe, humans will never be able to leave the local group (Milky Way, Andromeda and a few globular clusters). This volume of space has a diameter of 9.5^24cm or a spherical volume of 4.5^74cm^3. If we plug that value as the 'new' volume of the 'universe' in the equation from above. (((26/7)xPcritxOMEGAbxV)/Mp) We get the total number of particles in the local group to be 4.2x10^68. With the amount of particles per person averaging 1.46x10^29, the number of humans to use all the particles in the local group is 2.9x10^39. Then all we have to do is solve for time using the rearranged population growth equation with the new total population. T= (1/r)ln(Pall/Pnow) r = 1.11% Pnow = 7.5x10^9 Pall = 2.9x10^39. T = 6138yrs It would take 6138 years for the human population to use all of the particles available to humans (the amount the local group). Or 71.3% of the time it would take to use the entire universe. PLEASE CHECK MY MATH Thank you for the knowledge, wonderful videos as always.

[@ashkara8652]

Some videos have misleading titles; not really teaching what the title says. And then there's Numberphile; you learn a ton of other things along with what's in the title of the video. Love you guys!

[@scarcade2070]

Am I the only one shocked about the "8604 years to go" part?

[@martiddy]

SCArcade Yeah me too, I didn't expect such a small number. But good news is that population growth is decreasing in highly developed countries.

[@adamcordingley2572]

SCArcade not at all

[@monglold]

It reminds me of the fact that if you could fold a piece of paper 40 times, each time you would be doubling its width. Doing it 40 times would multiply its width by 2^40, which would be wider than the diameter or radius (cant remember) of the observable universe. Just goes to show how exponential growth works

[@e1woqf]

No, I was shocked too

[@alihajiya2572]

SHOOK

[@la_gej_]

8604 years seems too few to be real, can we call it the Parker time?

[@Phelan666]

It's not real. The human population will be reduced dramatically when diseases become fully resistant to antibiotics.

[@rd-6137]

Yes

[@tpd8862]

No it's real... 7.5*10^9*1.0111^8604 = 1,33*10^51

[@echo5delta286]

That seemingly short time doesn't address the fact that trillions, if not all, of the particles in any given human being used to be part of a different human being (a few thousand years previous) and will again be part of a different human being in the far future. We're not "using up" the particles--we're recycling them. Also, organic populations don't grow exponentially. They grow logistically, and logistic curves ultimately show decelerating growth and an unreachable upper limit to the size of a population.

[@Alasius]

Though the number itself won't fit the reality, your answer "why" is wrong. It is only watching at the simultanously used particles and therefor the equation is in theory correct. It lacks that the ratio won't stay at 1.11 percent per year.

[@HappyMathDad]

That last bit of info at the end of the video is awesome! great work you guys!

[@blasder007]

I imagine this video as the first scene of a movie and then we see our society 8000 years later in a galactic dystopia

[@mihailmilev9909]

@@drenz1523 yeah pretty cool

[@mihailmilev9909]

@@drenz1523 hello fellow human form the recent present

[@bestnocture]

Number of particles in the universe is of course -1/12 .

[@Bananakid11]

may I ask you why?

[@javier8920]

Ich Selber It's a joke about the sum of all integers

[@adamkarnbrink3305]

Numberphile made a video about -1/12. You'll understand if you watch it.

[@xenocritinpi87]

@@Bananakid11 The sum of all Natural numbers: 1+2+3+4+5+6... = (-1/12)

[@jazzabighits4473]

@@xenocritinpi87 no, it's infinity

[@bluekeybo]

This video got a real genuine laugh from me towards the end. Thanks Numberphile!

[@therealzilch]

Some very interesting numbers there. Thank you. cheers from sunny Vienna, Scott

[@scottwilson4798]

Is math related to science

[@pzyckox]

Depends on the science

[@SomeAHole]

Christian Kjeldbjerg Kristensen It's a meme

[@pzyckox]

Oh the Neil de Grasse thing! Had totally forgotten that' was a thing. Thanks for the reminder.

[@KupoPallo]

science is related to math

[@pzyckox]

What about social science?

[@Nilguiri]

I notice that Tony Padilla has finally given up on his quest to bring back the long scale numbering system! 7:28 He called 10`9 a billion!

[@rhoddryice5412]

Sadly.

[@randomnamegbji]

Super interesting topic Brady! More like this!

[@ethanmacmillan1375]

Amazing video!!! One of my favourites in a long time!

[@yaerius]

those are some really amazing calculations! I hope they last for the next 8604 years.

[@HUPextreme]

any reason why the triangle on the left in the thumbnail is filled white....seems like a mistake to me.

[@leepoling4897]

Hetesh Patel I believe it is

[@massir7769]

Hetesh Patel illuminati confirmed.

[@redbeam_]

what triangle

[@gamedoodles]

A Great one. Thanks Tony and Numberphile.

[@potawatomi100]

You guys are brilliant and your videos are interesting and informative.

[@ronror]

There are 10 million million million million million million million million particles in the universe that we can observe, yo mama took the ugly ones and put them into one nerd!! Sorry I've waited 6 years for that xD

[@Matt_10203]

Light Yagami Epic Rap Battles ;)

[@akshatsaxena1431]

Light Yagami was it worth the wait

[@ronror]

Akshat Saxena extremely worth it XD

[@AGoldSoldier]

Light Yagami Huh, I never thought an old ERB vid would ever be relevant

[@apetrenko_ai]

I am a super computer you're like a TI-82, whoo!

[@theskepticalapple4203]

I literally wondered what the answer to this question was this morning.

[@DuCaDo003]

I knew this would be Dr Padilla when I read the title. He gets so excited about large numbers! Also a great little walkthrough of how to use symbols to build equations. This video could easily be on 60 Symbols, but it has enough math(s) for Numberphile. Is it on both? I haven't checked. It should be. A dual release. Wasn't someone asking how math relates to science?

[@brianhourigan]

I always find Tony one of the easiest guys to understand on Numberphile/Sixty Symbols

[@J0R1AN]

I think you did something wrong. My answer was -1/12.

[@vircaprae3060]

-1/12, the 42 of mathematicians

[@Kitty-hx2pr]

The universe is a gold nugget now.

[@dcs_0]

Lol but they actually did do something wrong. They rounded the p(all) to 2.25x10^51 so their calculation is slightly off. I used the non-rounded values and got 8652 years

[@qwertyquazo673]

Mine too.

[@CCRLH85]

They used three significant figures for everything (except for their answer *tsk tsk*) but, a difference of less than 50 years is minor on that scale.

[@MrStevenToast]

this is why i subscribed to this channel....

[@jemmerx]

What a co-incidence. I was just wondering a few days ago how we'd estimated the amount of particles in the observable universe. I knew the number but not how they knew. Thanks Numberphile!

[@BrightEyes83]

this video is incredibly satisfying because it seems obvious to me that we can't carry on this way for too much longer.

[@PetraKann]

Interesting how the ancient Greeks were also concerned with this question. (I believe that the great Archimedes estimated the number of particles in the Universe to be 10^79 which is low but a reasonable estimate. Amazing that over 2200 years ago the Ancient Greeks were thinking about large numbers with 79 zeros)

[@Thror251]

I don't believe they got within 1 order of magnitude. Source?

[@tomonetruth]

@@Thror251 they certainly weren't "thinking about large numbers with 79 zeros"

[@matthewschwartz8730]

Consider this, ancient Greeks thought matter was made of tiny indivisible particles and I believe the number is very close when dealing with total atoms. Not commenting on the validity of the statement...if true it is very amazing.

[@PetraKann]

@@matthewschwartz8730 Indeed it was Democritus who was the father of theoretical Particle Physics. He suggested in a thought experiment that if you cut matter up into smaller and smaller bits, eventually you will arrive at a "bit" that is indivisible and he called that bit "atomos" or atom as it is known today. The Ancient Greeks also made estimates at the total number of "atoms" in the Universe. Archimedes concludes that the maximum number of sand grains that can fit in the Universe is 8*10^63. If we consider that a sand grain contains about 10^17 atoms then we get an order of 10^80 atoms which is an approximation of the number of atoms of the entire Universe that current modern science estimates. The actual experimental proof of the existence of "atoms' came over 2,000 years later (John Dalton in 1808)

[@vodizzzle]

The ancient Greeks did not know about most of the things discussed in this video and had a COMPLETELY different view on the universe… Radius of the observable universe? Quarks? Hydrogen? The existence of protons was only discovered 100y ago… so even they might ended up in the right ball park , it was purely accidental and based on entirely false premises…

[@ScriptGuider]

Ironically, this video actually makes the universe seem very... small.

[@MacDaniboi]

Wow this blew my mind to bits.

[@juanjoseguva]

Anyone else stoked to see Brady's drone footage sometime in the future? Thanks for the consistently awesome content, fellas!

[@Makebuildmodify]

Considering that the particle to human conversion was possible. I wonder how our distance to the particles would affect the growth rate. With the edge of the Universe at 46.5 billion light-years away people would have to consume particles at faster than the speed of light to achieve complete consumption the 8604 years.

[@marlonyo]

yes

[@fredericlegrand270]

Which means that our grow rate HAS TO reduce at some time (signed :Tanos)

[@atakanaydn5751]

I love how your comment sounds as if it is our goal to consume the universe in 8604 years xd

[@Makebuildmodify]

@@atakanaydn5751 Lol!

[@alephnull6691]

he doesn't account death rate.

[@parthiancapitalist2733]

How many universes in a particle.....

[@AnimeHumanCoherence]

:0

[@MachineGunX2]

24

[@thatoneguy9582]

Ancient languages and history 1/huge number

[@simatbirch]

42

[@MatiasIsasmendi]

@ccc310 yes

[@dudhauwhejrnrk]

knew it would be tony! Love it

[@rakka1dude184]

this is only the dynamic element count but the permutations of this is phenomenal considering the space they move in is liquidlike as well!!

[@devansurf]

Someone please count how many folds were created on his forehead 0:18

[@fergusmaclachlan1404]

About 10.

[@fergusmaclachlan1404]

Give or take a few semi-folds.

[@slickerius]

devansurf Done my extensive calculations using advanced formulas and constants, the answer is -1/12.

[@domodel01]

I counted 11

[@PaulPaulPaulson]

There is only one particle which time traveled back to the big bang over and over again

[@SilentBudgie]

😵

[@PaladinswordSaurfang]

If you're talking about the Big Bounce, that's been debunked.

[@Eduardo-bq6is]

This is so f**king amazing, i love it

[@kmac499]

brilliant piece of calculation. one last step please. what would the average distance between humans be?

[@RenanHirayama]

The less present atoms in the Universe shouldn't be ignored, I guess. There are way more particles stored in heavier elements than in H and He, and this was used to calculate the number of particles in a human body. Anyway, this is a very fun thing to think about.

[@Dr._Atom]

Uhhh nope, last time I checked, the universe, the normal matter part, still consists about 75% hydrogen and about 25% helium. Meaning there are still way more particles in those two. Yes, heavier elements are also abundant from our pov, say they consist of like 10^78 particles, then you add it to 3.28 x 10^80, do you think you would see any difference?

[@procactus9109]

So its safe to assume that statistically there is not a singe particle in my flat mates head.

[@TheSmurfboard]

ProCactus Well then hopefully he's the one who always does the vacuuming.

[@Petertronic]

The number of permutations of a 7x7x7 rubik's cube is 1.95 x 10^160, just thought I'd throw that out there. Mind-blowing!

[@StreuB1]

This was really very cool.

[@kelbiekelbie909]

This could make for a good sci-fi movie.

[@theColJessep]

Looks like we need to start optimizing the biological support system for our brains.

[@Hy-jg8ow]

Why get stuck with biology?

[@SliptOnAChip]

Amazing!

[@jackpullen3820]

The drive of the expansion of our universe from the quantum gravity field is creating new particles much faster than your calculations of people using them up. On the other hand, I love your math lesson! COOL!!!

[@owlofminerva1397]

Title should be: How many particles are in the Universe? Then we see a mathematician having fun calculating ridiculous stuff :)

[@carlkamuti]

Owl of Minerva I believe he's a cosmologist.

[@luisabotero378]

Wait but all this is about the observable universe. We don't have anyway of knowing how many partials are in the entire universe, do we?

[@martiddy]

Luisa Botero You're right, to know how many particles there are in the entire universe we need to know its total size. And we have no idea how big it is (a light so far take millions of years to get to the Earth)

[@sakadabara]

Vapor Wave - sama , if it took billions of years , how come we still have radioactive elements?

[@martiddy]

Nikolai Tsakov Because almost all the radioactive atoms that we have here on Earth where made from the Sun, and since it's relatively close, radioactive elements can "survive" a couple thousands millions of years until we discover them (or make new ones in laboratories and particle colliders)

[@adrienufferte]

AMAZING !

[@mortenstabenau9177]

@7:47: I might be wrong, but your exponential growth function seems off. If we say want to calculate the population next year, using this formula we would get P_next = P_now * exp(1.1) = 3 * P_now. I think the right formula should be P_all / P_now = r^(T / 1y)

[@danielgrass9881]

Although the particle to baryon ratio is close to accurate, the method arrived to reach the ratio is fundamentally flawed. This video uses proportions of atoms, not proportion by mass, the latter of which is where the percentages came from. Using those proportions, but now by mass, we get 62 particles/16 baryons, not 26 particles/7 baryons. Using more accurate percentages, we arrive at 3.87 particles/baryon, which is much closer to 62/16 than 26/7.

[@uweperschke6799]

Isn't there a similar flaw in the human body particle count? Based on an atomic percent distribution of H:O:C = 62:24:12 I get a P/B ratio of 2096/98~˜21,38. Barion mass: ~1,67E-17g. Thus barion count in 70.000g~4,19E+21 and particle count~8,95E+22, not 1,46E+29. Which leads to 3,66E+57 humans to use up all particles, or 9892 years.

[@marlonyo]

this is why in this calculations worrying about the details is mostly useless since the important stuff is mostly the order of magnitude that this number is below or nearly 10,000 years a nothing in cosmological time

[@3117master]

THE END IS NIGH!

[@martiddy]

1337master I thought the end was day

[@randomVimes]

Excellent channel! I request a video about factorial number system ^^

[@bleesev2]

I'm a little bit confused. In the calculation the numerator is the total energy of the universe contributed by baryons, but in the denominator it is the mass of each baryon. Wouldn't you first need to convert that mass into energy (can assume each baryon is at rest so you just multiply the mass by c^2) in order to get the actual number?

[@jamescollier3]

that converts to 5% of the universe is matter that we are familiar with

[@attackzombies9772]

You forgot to account for the rate of growth for the observable universe by the time humans use up all the particles in the now observable universe.

[@eruyommo]

Attack Zombies I think that eight thousand years light of more diameter would not affect the order of magnitude of the result.

[@zaephou2843]

But the universe is expanding faster than the speed of light.

[@pyraliron]

observable universe*

[@SirFatCatt]

It'd probably be a lot longer than 8600 years if they did. I think it was more of a "in the current observable universe" kind of deal, not the whole universe thing.

[@nikospagonas]

Attack Zombies actually if you did it like that, it would turn out to be impossible. Since humans continuously expand, so does our ability to observe the universe, so we will always observe more the more we become. Interesting...

[@smartstreet1720]

amazing

[@joshyoung1440]

One thing that tripped me up is that at 3:17, the title says "energy density stored in baryons" but it would be more accurate (perhaps just accurate) to say that you're finding the total barionic energy, which you then turn into density by using the volume. Cause for the life of me I was getting lost at how he was naming the variables and the answer until I was like "okay... this is just total energy... times the percentage that's stored in baryons... gives us the total energy stored in baryons. There we go." Density wasn't quite involved yet.

[@nathanielpranger7370]

The omission of DEATH from this estimation might be a significant error.

[@kamon9339]

yet there are 10^120 ways to arrange all pieces on a chess board... imagine how many ways there are to arrange all particles in the observable universe. i would like to see a video on that

[@1dgram]

FailebyI guess you could use planks constant to get the smallest possible position, see how many possibly positions there are in the observable universe, then use the number of distinct particles (hint: I believe quantum mechanics says this is very small - less than 100), the number of each type in the observable universe, and then use combinatorics to calculate the number of ways of arranging these distinct particles keeping in mind that some are allowed to occupy the same positions (again quantum mechanics)

[@lemmysverruca]

The result would probably still be smaller than Graham's number.

[@CrushOfSiel]

Before I decided to go back to school and get my PhD in physics I remember doing an order of magnitude estimate at my old night job (I used to do all types of silly things to pass the time during the long boring night). I came up with about 10^80 *atoms* in the universe. Which should be pretty close to within a few orders of magnitude of number of particles. Pretty cool we're in such close agreement :).

[@numbermathematics4137]

observable universe is of finite length but other part of Universe that spreads rapidly is a amazing thing to discover.

[@alvincay100]

Al Gore will be releasing an Inconvenient Truth part 3 later this year to address this problem.

[@bladdnun3016]

1. If 75 % of baryons are stored in hydrogen and 25 % in helium, that means that the H : He ratio is not 3 : 1 but 12 : 1. 2. If the borders of the sphere of human civilization would expand with the speed of light from this day on, how long would it take until all particles within that sphere would be taken up by humans?

[@daxafer]

bladd nun I noticed the same error (4:52) but you worded it much more neatly He said "75% of baryons are in H, 25% in He" but the source of this ratio comes from analyzing gas clouds. So, perhaps he misspoke and meant to say that 75% of the atoms (or nucleui) are H. However, the error is still less than one order of magnitude, so perhaps it doesn't make a significant difference in the answer.

[@PeterAuto1]

the number of years would change in the single or double digits. the growth of the universe is only cubic and the growth of human population is exponential. which is much faster

[@bladdnun3016]

What I meant to describe is a scenario in which humans set out to consume as much of the universe as possible, starting from the earth. They are only limited by their maximum travelling speed and speed of reproduction. The growth of the universe is negligible in this context, as they will not even reach the center of the galaxy before having consumed everything they could get their hands on.

[@baburaoganpatraoapte227]

Only channel on KZbin that still upload 9:58 long video.

[@BigB1Lachi]

Compound Interest is the strongest force in the Universe

[@Groink1]

He is telling me that the universe is basically flat. A minute later he uses the volume of a sphere in his formula. What did I miss. I am confused.

[@TheGuyCalledX]

I had the same question

[@oskarekberg3704]

Groink1 I'm assuming he means it's a flat three-dimensional space, and not a curved one. Easier to picture with 2D, since we can have a flat 2D-space (a flat piece of paper) as well as a curved one (we can for example fold the paper to a tube). Thus is a big sphere perfectly compatible with a flat 3D-space.

[@Doggaebi.]

The observable universe is a sphere from our (Earth's) perspective. However I'm not sure what he means by it being kind of flat either.

[@GreaterDeity]

Frz How do we know that... when we haven't observed it?

[@Pulsar77]

In cosmology, 'flat' is another word for a 3D space with no curvature, i.e. a Euclidean space, where the Pythagorean theorem holds.

[@MrMartin1538]

What fascinates me the most is the Complexity of the Universe.We have such complex Things such as Life,Planets and Computers and in the end it´s 17 Subatomic Particles and 4 Fundamental Forces. At least in the Standard Model and not accounting for Dark Matter and Energy. That´s the most fascinating for me. We’re Atoms,a part of the Universe thinking and exploring itself.Every thought,memory,every Piece of Music or Art ever made created by some chemicals in your brain all made out of these subatomic particles in the end.

[@kadlubom]

Mind blown!

It's over 9000!

[@spitlerspitler]

"... in so many years ... we wouldve used up all the particles in the universe" thats only if every human is born with completely new atoms, nothing can be reused from previous generations anyone wants to bother working out what that number would be if you allow for recycling? One has to somehow estimate a lot of stuff i dont know how to (i know this is the second comment in 10 min)

[@brettfinley8041]

The population increase rate given is with death rate factored in.

[@abelramirez7320]

Who else regularly watches numberphile videos even though you can't understand just what in the god damn is happening?

[@santrigel]

Thanks for the video. Just wondering that the ratio 3:1 between hydrogen and helium is for the mass of the elements not for the number of proton?

[@ragnkja]

Mass of elements or number of baryons, which tend to be very close to the same thing.

[@JanSanono]

666th view😏😏😏

[@gauravkar4805]

Surely less than a google(googol).

[@BrownHairL]

It is less than a googol, but only because the universe is not very dense at all. If it were ~ 5 x 10^19, times more dense, which would still not be all that impressive, it would reach a googol.

[@bacon5869]

Its a googol times more than a googol.

[@Ostbuggen]

Really shows the power of exponentials. Compound interest is the most powerful force in the universe.

[@dawicool2]

when you calculate the total energy stored in baryons shouldn't the volume be 4/3*pi*(L/2)^2 since L is the distance between one end and hte other and I assume you are calculating the volume of a sphere?

[@Kitty-hx2pr]

11 people hate the universe.

[@boda1948]

Should i mess it up and like the comment? Nahhh

[@hartschteiler3363]

I say 12!

[@axelnilsson6478]

479001600 is a bit less than that

[@MrRagusa76]

I love the video's starring Tony.

[@vyslr]

Correct me if am wrong but you said that the universe is nearly flat but while you are calculating the volume you used sphere formula right ? How does it work

[@jlxip]

Why don't you just write g/cm^3 instead of gcm^(-3) ?

[@ahmetmuratcelik6806]

JlXip because its cool.

[@caughtexception611]

gcm^(-3) is standard physics notation within the profession, from what I remember.

[@Doggaebi.]

That's the format you write it in, g/cm^3 is for GCSE students and below. That's how it works in England anyway.

[@Pestrutsi]

same difference, just a matter of convention

[@Fummy007]

University notation.

[@lughaidhmoutia3589]

It should be 1.01%/year. Someone do the maths.i guess trillion of years

[@MrxstGrssmnstMttckstPhlNelThot]

I get 10,140 years. Still not a lot. And that's going with another commenter's (Daniel Grass) slightly more accurate particle:baryon ratio of 3.87 particles per baryon. Still not a long time for humanity at this rate. We gotta slow down our growth rate or discover FTL or we're doomed mate.

[@brewbrewbrewthedeck4138]

Bravo, another utter failure at understanding exponential growth, lughaidh. You all would benefit from watching Albert Bartlett's lecture on the topic (available here on KZbin).

[@EmissaryOfSmeagol]

That sponsorship transition was smooth

[@98DSi]

i had to pause because i couldn't stop laughing at "Why's it in centimetres??"

[@code-dredd]

So, if it'd take roughly 8.5K years to consume all particles in the _universe_ as humans (i.e. ignoring animals and billions of other living organisms), how is it that, in the millions of years that the universe is said to have been around, these particles have not been consumed already? It looks like they should've been consumed many times over by now.

[@sakadabara]

ray , something more: how do we still have radioactive materials left , for all of these years?

[@code-dredd]

Nikolai Tsakov Well, based on the calculation done in the video, it's contradictory for the following reasons: 1. The universe is _believed_ to be billions of years old (~15 Billion) by many (not all) scientists[1] 2. The mathematical calculation shows it'd take ~8.5K years to "transform" _all_ particles in the _universe_ into human beings 3. Humans are _believed_ to have been around for several million years (~3 Million) by many (not all) scientists[1] Even if the mathematical calculation is very simplified, it seems very unlikely/doubtful that tweaking it will account for the vast difference between ~8.5K and ~15G years. Assuming the math in the video giving 8.5K is correct, a number which is an _upper bound_ and not the actual time, it seems the only real alternative to solve this blatant contradiction is to reject the idea that the universe is as old as some claim, because, clearly, we're still here. In fact, it should be a lot less, since reality does not ignore the presence of other non-human organisms that also "consume" particles (e.g. plants, other animals, etc), which the video's calculation does not account for. It would've been nice for what seems to be an observed and obvious contradiction to have been addressed in the video. [1] Note that this is sort of a moot point, since the question of how long the universe, humanity, and other things have been around are questions about the past, which are actually questions of _history_ rather than _science_ (i.e. scientific method, which starts with direct observation and must be repeatable, cannot be applied to unobserved/unrepeatable historical events, by definition).

[@Mandorle21]

ray Man you are ignorant... you know what history is, right?

[@sakadabara]

ray , you're very smart !

[@Goldfish1060]

Because they die and the atoms get recycled. These calculations are very lose and ignoring deaths, illnesses, etc.

[@valentinakaramazova1007]

first

[@valentinakaramazova1007]

no one cares you idiot

[@dootdoot6130]

tfw someone replies to their own comment

[@seantobin5235]

Lennox Xonnel whoa pretty edgy dude

[@LakierosJordy]

That's a really powerful calculation. 9000 years is obscenely low.

[@MatthiasYReich]

Could you make a video on that sphere-saddle-thing in the beginning? Didn't understand that...

[@Mark_Cook]

Matthias Y. Reich You can't visualize it but 3d space can (and does) be curved. Gravity is really a by-product of curved space caused by a lot of mass in one area. No one truly knows what the "shape" of the universe is although we believe it is relatively "flat" which means it isnt warped or curved in a universal scale. It's similar to a 2d space (a piece of paper) being curved into a tube or other shape, now apply the same thing to 3d space and you sort of get the idea.

[@MatthiasYReich]

Mark ah ok, yeah I more or less knew that, the way he said it it sounded as if it was flat in the sense that it's much bigger in two directions than in the third. Thanks for clarifying

[@kael13]

Hmm... 8000 years? Doesn't seem right... Not to mention we're supposed to be making it easily as far as the 41st Millennium.

[@kosuke-nightcoreunited7057]

Human Population Rate will go down, this and last century the human population growth is on a high peak

[@ragnkja]

Take this calculation as strong evidence that the population growth will not continue like this forever.

[@UnifyTruth]

That's the power of exponential functions; 8000 years doesn't seem right because you're thinking linearly.

[@iwillfreezeyou]

Kael you got it wrong, 8000 years assuming nobody would ever die... so in reality it won't happen

[@ragnkja]

Veinous Not 7.5 * 1.11, but 7.5 * 1.0101.

[@jpphoton]

WOW. Mind truly blown on watching this one from my (sorry) favorite guy. Damn.

[@mostafaelshamy5400]

well you see if you have one particle, and keep adding one particle to it an infinite amount of times( as the universe is growing infinitely ), you will end up with -1/12 particles. MINDBLOWN

[@just_a_guy123_]

at 7:44 arnt you forgitting all the deth, and decomposhishion of the body?

[@daviddamien7122]

I love Numberphile. It's a fantastic channel and so interesting. But the sound of that pen on the brown paper makes me with I was deaf, and I'm a musician.