How Many Atoms Are In the Observable Universe? (livescience.com) 77
Long-time Slashdot reader fahrbot-bot quotes LiveScience's exploration of the math:
To start out 'small,' there are around 7 octillion, or 7x10^27 (7 followed by 27 zeros), atoms in an average human body, according to The Guardian. Given this vast sum of atoms in one person alone, you might think it would be impossible to determine how many atoms are in the entire universe. And you'd be right: Because we have no idea how large the entire universe really is, we can't find out how many atoms are within it.
However, it is possible to work out roughly how many atoms are in the observable universe — the part of the universe that we can see and study — using some cosmological assumptions and a bit of math.
[...]
Doing the math
To work out the number of atoms in the observable universe, we need to know its mass, which means we have to find out how many stars there are. There are around 10^11 to 10^12 galaxies in the observable universe, and each galaxy contains between 10^11 and 10^12 stars, according to the European Space Agency. This gives us somewhere between 10^22 and 10^24 stars. For the purposes of this calculation, we can say that there are 10^23 stars in the observable universe. Of course, this is just a best guess; galaxies can range in size and number of stars, but because we can't count them individually, this will have to do for now.
On average, a star weighs around 2.2x10^32 pounds (10^32 kilograms), according to Science ABC, which means that the mass of the universe is around 2.2x10^55 pounds (10^55 kilograms). Now that we know the mass, or amount of matter, we need to see how many atoms fit into it. On average, each gram of matter has around 10^24 protons, according to Fermilab, a national laboratory for particle physics in Illinois. That means it is the same as the number of hydrogen atoms, because each hydrogen atom has only one proton (hence why we made the earlier assumption about hydrogen atoms).
This gives us 10^82 atoms in the observable universe. To put that into context, that is 100,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 atoms.
This number is only a rough guess, based on a number of approximations and assumptions. But given our current understanding of the observable universe, it is unlikely to be too far off the mark.
However, it is possible to work out roughly how many atoms are in the observable universe — the part of the universe that we can see and study — using some cosmological assumptions and a bit of math.
[...]
Doing the math
To work out the number of atoms in the observable universe, we need to know its mass, which means we have to find out how many stars there are. There are around 10^11 to 10^12 galaxies in the observable universe, and each galaxy contains between 10^11 and 10^12 stars, according to the European Space Agency. This gives us somewhere between 10^22 and 10^24 stars. For the purposes of this calculation, we can say that there are 10^23 stars in the observable universe. Of course, this is just a best guess; galaxies can range in size and number of stars, but because we can't count them individually, this will have to do for now.
On average, a star weighs around 2.2x10^32 pounds (10^32 kilograms), according to Science ABC, which means that the mass of the universe is around 2.2x10^55 pounds (10^55 kilograms). Now that we know the mass, or amount of matter, we need to see how many atoms fit into it. On average, each gram of matter has around 10^24 protons, according to Fermilab, a national laboratory for particle physics in Illinois. That means it is the same as the number of hydrogen atoms, because each hydrogen atom has only one proton (hence why we made the earlier assumption about hydrogen atoms).
This gives us 10^82 atoms in the observable universe. To put that into context, that is 100,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 atoms.
This number is only a rough guess, based on a number of approximations and assumptions. But given our current understanding of the observable universe, it is unlikely to be too far off the mark.
Many inaccuracies (Score:1, Troll)
This estimate contains many silly inaccuracies.
For instance, it assumes all atoms are in stars. Actually, only about 10% of atoms are in stars, with the remainder in the interstellar medium.
It also assumes that there are 1e24 atoms per gram. Anyone who passed high school chemistry should know that is wrong by a factor of two.
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>1e24 is wrong by a factor of two
So 2e24? That sort of distinction is discarded in back-of-the-envelope math
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No, in the other direction: roughly 6e23 (more precisely, Avogadro's number) protons in a gram.
It doesn't take many errors like that to add up to several orders of magnitude. The star vs interstellar gas difference mentioned elsewhere, if accurate, is an order of magnitude all by itself.
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6e23 is 0.6e24 which is (at the scale we're talking about) roughly 1e24.
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6e23 is 0.6e24 which is (at the scale we're talking about) roughly 1e24.
Sure, the inaccuracy is just one extra universe. That doesn't really matter if you are just looking for a ballpark exponent.
But an article published on the front page of Slashdot perhaps should be a bit less half-assed about it.
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6e23 is for hydrogen. The universe is 25% helium, and about 2% other stuff.
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6e23 is for hydrogen. The universe is 25% helium, and about 2% other stuff.
Irrelevant. You are getting caught up in insignificant detail, in an order-or-magnitude estimation.
The only major error in the summary is in the stupid conversions from metric.
10^32 kg is 10^32 lb, not 2.2x10^32 which implies a precision far beyond what the article is using.
It is like translating "give him an inch" to "give him 2.54cm".
Bigger Inaccuracies (Score:2)
So 2e24? That sort of distinction is discarded in back-of-the-envelope math
True, but that's far from the only error this guy made. First, most of the stuff in stars is not actually atoms because stars are hot it's a heavily ionized plasma not atoms. If you want to count atoms you need to estimate the cold, baryonic matter which is non-luminous. This is hard because you also have non-baryonic Dark Matter as well and about 6 times as much of it.
The original article is a hodge-podge of half-understood physics and unforced errors where the author adds in irrelevant facts to show o
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First, most of the stuff in stars is not actually atoms because stars are hot it's a heavily ionized plasma not atoms.
Wrong. Wrong wrong wrong.
Plasma is superheated matter – so hot that the electrons are ripped away from the atoms forming an ionized gas. It comprises over 99% of the visible universe. https://www.psfc.mit.edu/visio... [mit.edu]
Plasma is atoms that have no electron. But they're still atoms. You can't destroy atoms until you get to the level of a neutron star. If there were no atoms in stars they what the hell do you think they're smashing together to produce energy? Hint... ATOMS. H at first, then He if
Confusing Atoms and Nuclei (Score:2)
Plasma is atoms that have no electron. But they're still atoms.
An atom is, by definition, an electrically neutral bound state between a nucleus and electrons. The name for what you refer to as "an atom with no electrons" is a nucleus not an atom and it's about 10,000 times smaller than an atom.
You can't destroy atoms until you get to the level of a neutron star.
I've destroyed atoms by simply taking off a woolly jumper on a dry winter's day and converting lots of atoms into ions due to the static electricity. I mean you are technically correct that triggering a massive supernova and collapsing the core of a giant star to the point where
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I've destroyed atoms by simply taking off a woolly jumper on a dry winter's day and converting lots of atoms into ions due to the static electricity.
I disagree. You didn't destroy anything. Any of those atoms that you stripped an electron from would have instantly grabbed a spare electron and become "an atom again" the moment it cooled down below whatever threshold is required to strip said electron from its host nucleus.
It would require a big-bang process to create an atom out of thin air.
I disagree with your definition of atoms. I mean, technically, maybe there is a different scientific term for it.. I'll give you that, but any ion becomes the sam
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You didn't destroy anything. Any of those atoms that you stripped an electron from would have instantly grabbed a spare electron and become "an atom again"
Ions do not "instantly" grab electrons there is a time period involved and, during this time period, there is no atom. Hence the atom is no more, its existence has ended, it has ceased to be or, in other words, it has been, in a word, destroyed. True, it can be reassembled but "destroy" just means to end the existence of something, it does not imply that it cannot be reassembled afterwards.
It would require a big-bang process to create an atom out of thin air.
Producing an atom out of "thin air" is _really_ easy, just reach up and pick one out because air, even thin air, is f
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p> They are smashing together nuclei, not atoms this is why the process is called nuclear fusion and not atomic fusion.
Going to disagree with this too. Too inaccurate. They aren't just smashing nuclei. They are ONLY smashing the nuclei of Hydrogen atoms (at least at first). There's more to it than simply being a nuclei. It's a very specific nuclei.. i.e. minus the electron, there is still the bit that makes it a hydrogen atom.
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True, but that's far from the only error this guy made. First, most of the stuff in stars is not actually atoms because stars are hot it's a heavily ionized plasma not atoms.
Shock! Horror! A popular science article makes simplifications! If you want a more precise definition of atom, the reader only has to click the hyperlink in the first line of the article.
If you want to count atoms you need to estimate the cold, baryonic matter which is non-luminous.
No, he doesn't. It is completely obvious from the beginning that the article is about baryonic matter. And that it is written for an audience who would not understand that term. Don't be such a pedant.
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The real answer is nine. I checked and checked again.
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This gives us 10^82 atoms in the observable universe. To put that into context, that is 100,*lots of zeros removed due to ascii art filter* atoms.
No, 10^82 = 10,*lots of zeros removed due to ascii art filter*
81 is a factor of three, so 82 only adds one more order of magnitude, not 2. Even students trained with the common core math syllabus would get this one right.
ps: had to modify because including all the zeros makes the filter think my comment looks like ascii art. I'm quoting the summary you useless system!
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Indeed - my favorite inaccuracy is from the summary:
my favorite part too! saying that expressing a huge number in decimal form "puts it in context" is a quite elaborate way to say that the whole context is just bogus nonsense.
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It also assumes that "dark matter" is a real thing, and that if it exists rather than merely being experimental skew of extraordinarily ancient and remote cosmological objects, and that "dark matter" is not difficult to detect baryonic matter such as rogue planets.
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Quite right. Have to take into account every sun shepherding gases out of their solar system, the solar wind versus gravity, not in orbit, either falls inward till it is or escape to form dust clouds between stellar systems and then out to between clusters of stellar systems, eventually forming new systems through gravitational pull after the distant solar winds pushed them together over aeons, they would high in hydrogen and form large stars.
Then there is the point that atoms and be created and destroyed
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"we have no idea how large the entire universe really is"
I think we have a pretty god idea, actually.
Definitely far more idea than most of the other assumptions made in that summary.
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No. We don't even know whether the universe is infinitely large or not (and if infinite, which order of infinity). We've got guesses, with reasonable arguments, but they go in multiple directions. What we've got a good estimate for is "the observable universe'.
Now if you assume that "the big bang" was the creation of the universe, then it's possible to make more detailed estimates, but we still wouldn't know how large it really was by a few orders of magnitude. And that assumption is just an assumption.
high by a factor of 100 to 1000 (Score:5, Informative)
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Honestly, I would have no idea where to even start with a calculation like that, especially given our ability to accurately estimate things like the number of stars in a really distant galaxy.
At first a margin of error of two orders of magnitude seems like a pretty big deal. Then you think about the size of the problem (Douglas Adams: “Space is big. Really big.”) and suddenly that limitation on
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What are the error bars on those estimates? That's the kind of number where I'd be suspicious about a few orders of magnitude being significant What I find interesting is that it's considerably higher than 10^66 and a lot less than 10^132.
Big number,but... (Score:2)
Re:Big number,but... (Score:5, Interesting)
still a long way to a googol.
A googol is the number of cubic microns in the Universe.
A googol is also the number of years for the largest black holes to evaporate through Hawking Radiation. But by then, the Universe will be a googol times bigger than it is today, and almost every particle will be beyond the observable horizon from every other particle.
The heat death of a universe is a sad and lonely process.
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No, googol was really an outrageous pay demand from a woman left out of Square One Television...
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googol needs to go back to the crawls of the universe to keep their engine from looking stupid.
Reminds me of Epic Rap Battles (Score:2)
Damn Libs (Score:3)
Imagine using pounds for anything scientific.
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Imagine using pounds for anything scientific.
Well, if you can’t pay in euros, it may be the only option.
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Well, there was Mars Climate Orbiter [wikipedia.org] But, yeah, the use pounds in TFA is pretty ludicrous. Use of familiar units can be help people get an intuitive grasp of the masses being discussed but there is nothing intuitive about the masses of planets much less stars, galaxies, and the observable universe.
Number is wrong (Score:2)
perhaps the ultimate example of "it's relative" (Score:2)
But given our current understanding of the observable universe, it is unlikely to be too far off the mark.
It's kind of crazy to be talking about a number that wouldn't be "far off the mark", in fact would be surprisingly close, if it were only off by the number of atoms in a few hundred galaxies.
Aristotle? calculated grains of sand on a beach (Score:2)
It was one of those ancients, anyone remember who? Was the first to sort of use scientific notation to deal with big numbers. Which is what this is about.
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Re: Math (Score:2)
I was thinking it could be a factor of 10,000 either way.
Roughly close to standard estimates (Score:4, Interesting)
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Started writing this comment as a reply to another comment complaining about the use of pounds. Then I read more and thought it would be more helpful here.
The use of pounds in the LiveScience article (and copied in the summary) is just inane. They actually cite a page at scienceabc.com, which claims an average mass of a star around 10^35 grams.
If you must use pounds, at least preserve the implicit uncertainty in the original and just say around 10^32 pounds. Or, better yet, actually dig deeper into the s
Eddington's answer (Score:1)
To save you from counting the digits, that's about 1.57 x 10^79.
Zero (Score:2)
I have never even seen one atom, yet we are told there are millions of them. Do they even exist? Anyway, carry on I am late for my flat earther meeting.
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I have never even seen one atom, yet we are told there are millions of them. Do they even exist? Anyway, carry on I am late for my flat earther meeting.
wait a minute, they do claim some of the atoms are... "round", that can't be true, got to be flat! Let's schedule a few more meetings and do a press release next week.
Re: Zero (Score:2)
it's flat Earth not flat everything. The Earth is a specia case that is flat. The Moon and Sun are still spheres. (seriously, that's what most of them believe). It does explain the Moon landing hoax, you can't just walk around on a sphere.
Been there, done that. (Score:4, Interesting)
I always ask stupid questions like these from myself, and after I do some estimations in my head, I always come to the conclusions of "who gives a shit?" I mean, It's not like this number is as important of the speed of light or Avogadro's constant. Besides thinking that the number is almost unimaginable and might bring a smile to your face for 5 seconds, it has no consequential bearing.
Some other stupid questions I've asked myself:
- I wonder if there's a perfect mate for me out there. Answer: Who gives a shit? I'm never gonna leave my wife.
- Will Aliens invade us? Answer: Who gtives a shit? I don't have any control over it.
Next up... (Score:2)
... how many angels can dance on the head of a pin?
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Zero. Angels are human-like, mostly females.
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That was actually an interesting question. Given the assumptions of those considering it, the question was really "Can an infinite number of angles dance on the head of a pin? Or is there a maximum number?" Angels were assumed to be able to be any size from extremely large to very small, but how small? Of course, they didn't consider that the head of a pin was particulate at a really small scale, as that wasn't really relevant to the theological matter they were interested in.
This may be related to the
433,851 (Score:2)
Oh...Atom! Never mind... [mynamestats.com]
About tree-fity (Score:2)
Octillion? (Score:2)
Always changing.... (Score:1)
There's always exchanges where we activate e=mc^2, like where we're turning gas into energy... like whenever we're using transportation or cars, be it to space or any trip to the other side of town.
So, there's no way to count atoms completely without asking everybody to freeze for a moment.
Re: Always changing.... (Score:1)
The number of molecules can change during chemical reactions, but the total number of particles and individual atoms making up the molecukes does not.
You're thinking nuclear/atomic.
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There's always exchanges where we activate e=mc^2, like where we're turning gas into energy... .
No.
Not sure what has lead you to believe this, but this is not true. E=MC^2 is only going to come into play in nuclear fission/fusion reactors. Burning gas (natural or otherwise) does NOT do that. You're breaking chemical bonds when you burn gas, not nuclear bonds.
Isn't that a trick question? (Score:2)
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That's not quite right. It was protons and electrons appearing, and the idea was from (or at least supported by) the astronomer Fred Hoyle as part of the "Steady State" theory of the universe. That's been pretty much abandoned.
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That's not quite right. It was protons and electrons appearing, and the idea was from (or at least supported by) the astronomer Fred Hoyle as part of the "Steady State" theory of the universe. That's been pretty much abandoned.
Pretty sure that's the whole basis behind Hawking Radiation. Virtual particles bubble up from nothing, one is captured by the black hole the other escapes.. Net loss of energy for the BH.
a large but decreasing number (Score:2)
As the universe expands, more of it is going beyond our visible horizon.
And all the time Hydrogen is fusing into Helium, so there are fewer, but larger atoms.
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As the universe expands, more of it is going beyond our visible horizon.
And all the time Hydrogen is fusing into Helium, so there are fewer, but larger atoms.
Nobody knows that for sure yet.. Because the CMB is still visible. We can't see thru the CMB since everything before was opaque.
Significant digits on estimates! (Score:2)
> On average, a star weighs around 2.2x10^32 pounds (10^32 kilograms)
It's amazing to me that science journalists (or their editors) completely don't understand significant digits or orders of magnitude in estimates. The average for these purposes is the same for pounds and kilograms!
Science journalism keeps getting worse and worse.
Different format, not context (Score:2)
This gives us 10^82 atoms in the observable universe. To put that into context, that is 1-and-83 zeroes atoms.
Re-writing 10^82 as 1 followed by 83 zeroes does not "put that into context" - it's simply a different (and incorrect) way of writing it.
But... (Score:2)
Is the number of hairs that Slashdotters can split greater or less than the number of observable atoms????
When trying to guess the number of atoms in the universe if we can get within two or three orders of magnitude I'd be surprised. But it does raise some interesting questions, like does a neutron star count as a single nucleus?? What about the matter inside black holes, does that still count as observable?
Finally a good application for ipv6 (Score:2)
Let's assign an ip address to each atom.
Re: Finally a good application for ipv6 (Score:1)
The real answer is ... (Score:1)
I'm an American (Score:2)
And you have my permission to leave out pounds when measuring the mass of a star, planet, moon, or asteroid. I can handle kilograms well enough to manage in a science article.
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And you have my permission to leave out pounds when measuring the mass of a star, planet, moon, or asteroid. I can handle kilograms well enough to manage in a science article.
They don't have my permission. Everyone knows that metric = communism. :P
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Also, stars are not made of atoms.
Yes they are. They most certainly are. Unless you're talking about a Neutron Star or a Quark Star, then every other star in the universe is made of atoms.
What the hell are they teaching you people in school?
Problem solved (Score:1)