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I think I am not alone who saw videos about that we (humans) are made of same atoms which someday were in stars. In other words, some atoms in our bodies are from stars which exploded billions of years ago.

I wonder if it is indeed true. I mean human's life begins when sperm cell fertilize egg cell. Now does that sperm cell or egg cell indeed contains some of the exact atoms from those stars?

I know little bit strange question, but would be interesting to hear if it is indeed true, that atoms in our body are same which someday were in stars.

In case you are wondering that's the video I am talking about: http://www.youtube.com/watch?v=9D05ej8u-gU

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As a side note on Neil deGrasse Tyson (NDT): he's a great speaker, and you might be interested in his talk for the SciCafe: youtube.com/watch?v=4KRZQQ_eICo –  stevenvh Feb 17 at 12:12
    
I will definitely watch this, sounds very interesting. –  user1880405 Feb 17 at 12:19
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5 Answers 5

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When the first atoms came into being in the early universe they were mainly hydrogen (the smallest atoms there are) and some helium. All over the universe those atoms lumped together under gravity until the pressure and temperature became so high that the hydrogen atoms fused together to form heavier elements. The reaction is nuclear fusion, and it's the engine of all stars. First hydrogen fuses to form helium, and then in a cascade helium atoms fuse to form heavier elements.

Many stars die as a supernova, without doubt the most violent explosions in the universe. The supernova which was just a single star becomes as bright as the complete galaxy it's part of. Remember that such a galaxy typically consists of 100 billion stars.

During the supernova explosion all the elements from helium to the most heavy elements are thrown into space. Later they will coalesce to form planets around new stars. So indeed, everything the earth consists of comes from such an exploding star.

And the next step is life. A single cell consists mainly of carbon, hydrogen, oxygen and nitrogen, all ultimately coming from the earth. For instance a plant will take these elements from the soil and the air, and we animals get it from plants. So the elements from the soil, which came from stars, ultimately ends up in each of our cells.

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This is so far most well explained answer, but it contradicts some other answers like Gerald's, who said that atoms in our bodies are not exact same from stars. –  user1880405 Feb 17 at 11:53
    
@user1880405 - Gerald describes radioactive atoms, which decay to slightly different ones. In that case the atoms aren't exactly the ones which originated in stars. But most atoms made in stars are stable, i.e. not radioactive. But even radioactive atoms don't completely disappear to form completely new atoms; you could say that for instance they retain 90 of their 91 neutrons, while the remaining decays into a proton. All within the same atom. –  stevenvh Feb 17 at 11:59
    
Gotcha. Now on a side note, why I asked my question in the first place, I thought maybe some of the atoms are already created in the earth in which case maybe all atoms in human are the ones which were created in earth, but not in stars. –  user1880405 Feb 17 at 12:04
    
Thank you everyone for taking time to answer! :) –  user1880405 Feb 17 at 12:08
    
@user1880405 - Yes, but as I tried to explain the planets are formed from the debris of exploded stars. Larger masses form stars, and the stars attract other debris, which either is absorbed or ends up in orbits. Planets in turn attract more space stuff. We're lucky to have the giant Jupiter to be a spatial "vacuum cleaner" which attracts many meteorites and other stuff which otherwise would end up on the earth. But all in all it's all traceable to exploding stars. –  stevenvh Feb 17 at 12:09
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Almost all hydrogen nuclei (protons), some helium atomic nuclei and traces of lithium nuclei are thought to have formed early in the universe, after the big bang. Almost all other atomic nuclei are thought to have formed in stars or have decayed from atomic nuclei, which have formed in stars. A minor fraction forms by high-energy collisions with cosmic rays.

The electrons of the hull of atoms in parts formed during the big bang, part of them come into existence, when neutrons decay to protons. These neutrons may have been free neutrons, or neutrons bound in instable atomic nuclei.

Hence our body doesn't contain the exact same atoms as they formed in stars. But without stars most of the atoms besides hydrogen in our body wouldn't exist.

Our body contains many of the exact same atomic nuclei, as they formed in stars, not the exact same atoms/ions.

To be a little more precise: Our body doesn't contain many free atoms, but mainly molecules and ions.

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Your body has hydrogen and heavier elements.

Most hydrogen in your body (really most of it) is primitive hydrogen from the origins of the Universe. Same would happen for Helium but we don't have it (almost none) on our bodies.

For all other elements, yes, they come (really most of them) from a star.

Sequence is approximately as follows:

When the Universe was young, our Galaxy was young: it was a cloud made of Hydrogen and Helium. Then, some stars (called Population III stars) were born and started burning hydrogen into helium, and on the latter stages of their lives they burned up helium into weighter elements like carbon, nitrogen, up to very small amounts of iron (the most stable element), and beyond that up to uranium.

Depending on their mass, of course. The smaller of these stars may be still around us, and the bigger ones exploded, sending these new elements to the galactic (a.k.a. interstellar) medium.

Then, from the now enriched medium, new stars were born (called Pupulation II stars). These ones had of course a lot of hydrogen and helium, but they had also some of the heavier elements. In turn, some of them are still observable (smaller ones, which last longer) and some of them exploded (bigger ones, which burn faster).

This second wave of stellar explosions enriched more the interstellar medium (gallactic medium) so a new generation of stars could be born. These are known as Pupullation I stars. Our Sun is one of them.

But not all the mass of the cloud which formed our Sun went into the Sun. Some if it made up the planets, and thus, ourselves.

So the atoms on our bodies come from the pre-planetary cloud, which consisted in original hydrogen enriched by Popullation III and Popullation II explosions.

Please note: due to chemical reactions, electrons in the atoms do not need to be the same they were while they were ejected by the stars, but the nucleus are.

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Thanks for a detailed answer. But I still didn't read answer to my question: are some of the atoms in our bodies are exact same which someday were stars? (Key word is "exact") –  user1880405 Feb 17 at 11:07
    
Answer for "exact" is "Most probably no" because all atoms in our bodies are involved in some molecule, which imples electron changes. If the question were about exact nucleus it would have been "Yes for most of them". –  Envite Feb 17 at 12:39
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Think about it this way, there are two options about how life began on earth: abiogenesis(life began on earth) and panspermia (life began somewhere else and from something like a meteor strike it continued to evolve on earth),at least those are the ones the are more dominant than other theories. Either way if life began to evolve on earth from matter that was on earth than it is suitable that whatever life evolved here would contain the same materials as earth, and earth originated from other starts, dust and debris that was around 4.5 billion years ago same thing for the second theory I mentioned. So I would suggest reading more on abiogenesis and panspermia it may satisfy your curiousity and answer your question.

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Thanks, I understand what you are saying, but I am asking a question: are some of the atoms in our bodies are exact same which someday were stars? That's all I ask and there is either "yes" or "no" answer to it. P.S. in no way I am trying to be rude. –  user1880405 Feb 17 at 10:57
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I might not be that much conceptual to you, but do you believe that stars are made up of Hydrogen (and Helium too). Hydrogen is a part of all the organic compounds. We humans are made up of billions of organic compounds, which in turn do contain Carbon, Hydrogen and Oxygen as their basic element and other compounds such as Sulphur, Phosphorus and other fats. And I guess a biology student would tell you more clearly what a sperm contains and what and how do these elements ressembles to those who are in Stars.

When a star collapses, it liberates out elements such as Carbon, Iron etc. Which maybe you're talking about. So that sperm consists of the same elements that the Star had at the time of its death (well not death you might know a better word for the star's ending period).

However, this doesn't make sense that these atoms are really the exact same or the actuall ones that were in the Stars many years ago. No such theory has been provided.

What does Star contain and what it liberates: http://answers.yahoo.com/question/index?qid=20080908195830AA5Iheb

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Thanks Afzaal. I of course understand that the same elements which are in human body were in stars, but my question indeed is, are there same exact atoms in our bodies from the stars, because it seems like that's what the video tries to say. –  user1880405 Feb 17 at 10:17
    
Hii @user1880405, I have already told you that I have not heard any such information, saying that the stars which ended up their life and now present inside our body. CARBON, OXYGEN and HYDROGEN that we contain is made up by our own body when we eat food, that is simple as that! These elements are made up in our body, and are not those which were in the stars... –  Afzaal Ahmad Zeeshan Feb 17 at 10:27
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Ha ha ha @envite what are you? An alien? Everyone knows that the body is made up of elements. And nuclear reactions are used to generate energy not elements. Elements are formed as a by-product. –  Afzaal Ahmad Zeeshan Feb 17 at 11:23
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@AfzaalAhmadZeeshan No sorry, Envite is correct: Our body is able to change molecules, not chemical elements. –  Gerald Feb 17 at 11:32
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@AfzaalAhmadZeeshan you said (cite) "These elements are made up in our body" and that is wrong. Then you said "the body is made up of elements" which is true. Please do not confuse one thing with the other. –  Envite Feb 17 at 12:37
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