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Nucleosynthesis and our Solar System. Currently, I am working on a project related to habitability. My primary focus is related to the unique circumstances that support life on Earth. I've encountered in several places that our solar system is comprised of around 2% heavier than hydrogen and helium elements, and that it most likely took around three generations of stellar cycles to reach that level. However, in a review article for a book—this is the only place I have found this information—it mentioned that only 0.2% of the visible universe is made up of heavier than hydrogen and helium elements. Therefore, I wanted to know if the figure of 0.2% heavier elements for the visible universe is correct. If so, do higher concentrations only occur in isolated pockets, such as our solar system? If that is the case, than how often do these pockets of around 2% concentration occur? Also, do astrobiologists use these pockets as focal points in their quests for life beyond our solar system? Ultimately, I want to make the case in my project that they majority of the visible universe is very low in its concentration of heavier elements, and periodically, heavier elements collect in an area that would sustain the development of complexity. I just wanted to know if this is a realistic conclusion, or if I am pushing the evidence too far. Thank you for your time and consideration. Also, any suggestions on references to academic materials that would support these conclusions would be greatly appreciated. |
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The fraction of normal matter that is neither hydrogen nor helium is called 'metallicity' by astronomers. This is a somewhat misleading name, since it includes carbon, oxygen, nitrogen and everything else other than hydrogen or helium even if they aren't what we would normally call a metal. Metall... Click here for more.
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Recent research into the possibility of the first life on earth forming near/in alkaline hydrothermal vents made me think...could scientists in a large lab recreate the conditions of those vents to see if they could recreate life? The lab would have to be extremely sterile so that any new molecules (RNA, etc) aren’t used by biological contaminants. |
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Scientists are doing exactly what you suggest! They are simulating in the laboratory the conditions believed to have been present at hydrothermal vents on the ancient Earth. They are doing this to test the hypothesis that life could have originated at hydrothermal vents when Earth was young (~4 bi... Click here for more.
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Is it possible that, when the core of Mars burned out, the water just sank to the center? This also raises the question to me, what's with the burning core of the earth, anyhow? Is Earth a star that is freezing over? As far as the necessity of extraterrestrial relocation for Earthen-life goes, I had always thought that the sun's expiration was our deadline, but won't our core expire before the sun does? |
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Both Earth and Mars are very different from stars. Stars are composed mostly of hydrogen and helium. Stars do indeed have cores that are burning, typically burning hydrogen to make helium. Planets like Earth and Mars are composed mostly of heavier elements like iron, silicon, and oxygen. The core... Click here for more.
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If something catastrophic may occur, wouldn't the governments and scientists deny it anyway to prevent mass hysteria? |
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I heard this claim often during the four years that I was answering questions from people who were concerned about some sort of cataclysm on December 21. (Incidentally, it was obvious to a scientist even four years ago that the fear of 12/21/12 was not based on reality.) Let me address your question... Click here for more.
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Are there any technologies in existence or development that can absolutely identify the presence of life on other worlds using the electromagnetic spectrum? How does the earth appear when viewed this way and is there a way to use it as a baseline for discovering life elsewhere? |
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Unfortunately, no, we do not have a fool-proof spectroscopic test for life. When we look at a planet as a whole, the spectrum is formed primarily by sunlight (or starlight) passing through the atmosphere. Therefore, the most likely spectral signatures of life would the presence of unexpected gases i... Click here for more.
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Do you think the earth will ever become "Non-livable" and we would have to go to that planet that is similar to earth? |
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I surely hope the Earth never becomes non-livable. If it does, it will be because we humans have messed it up. The worst we could do would not really make it non-livable, since the biosphere is very resilient, and after 4 billion years that is not about to go away. In any case, the idea of going to ... Click here for more.
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I've noticed in many of the answers you state that the far more pressing threat to our planet is global warming. However, I'm wondering what specific threats humans will face if the carbon dioxide levels continue to increase, in the worst-case scenario. What can ordinary people be doing to address the problem of climate change? |
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We are already seeing the impacts of global warming. The rapid shrinking of the arctic icecap has opened the northeast passage to shipping, and within a decade it will also open the northwest passage. The melting arctic ice and permafrost are exposing oil and mineral deposits for exploitation, but a... Click here for more.
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I'm from Brazil and I have just one question. If all these stories are true would you (the government) tell the truth to people? People would go crazy, would no longer want to work or do any other activity that drive the economy. So, would the government tell people about an imminent destruction of the earth in order to avoid chaos and madness? |
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Many people have asked me this same question, and I think it deserves a detailed answer. The question is based on two premises: (1) that the government would have unique information about some future catastrophe, and (2) that they would want to keep this information secret. I will concentrate on the... Click here for more.
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Why did the government make an announcement not to worry about 2012? How come nasa nor the government spoke about 2000 or 2003 like this but seem dedicated to make sure we believe 2012 are a hoax. is this a conspricy? AND If NASA is not worried about Dec 21, why did the head of NASA make a video warning NASA employees to prepare for disaster? |
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NASA has been answering questions from the public about doomsday 2012 for several years, including posting information on this website and on the nasa.gov website, but most media did not notice. As we have received more and more calls and emails from ... Click here for more.
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I just saw that you were featured on the news here in San
Francisco. I don't have a question. I just wanted to say thank you for
all of the time and energy you put into this. It is rare that there is
even someone willing to answer questions (no matter how crazy they may
seem) let alone not get so frustrated doing so. What touched me the
most was when you described the children who are worried about Dec. 21,
2012 and wanted to know as much as they could because they were worried
about their dogs. It makes me sick to my stomach to think that there
are mothers out there who are planning on "saving" their children by
killing them. I can only assume how reading those emails must feel, and
I hope you know that you are now in my thoughts. There are no words
that can express my heartbreak on hearing what some people have
planned. I wish there was something I could do to help. I guess that's
why I'm writing you. Just to say thank you on behalf of mankind. I wish
you all the best in life. Thank you again. |
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Thanks to the person who sent me this note and to dozens of
others who have expressed their gratitude for my efforts, and those of
my colleagues, who have tried to relieve people of their irrational
fears of 12-21-12. I particularly want to thank Bill Hudson of the
2012hoax website, Don Yeom... Click here for more.
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