What is Life on earth: Definition and 27 Discussions

The earliest known life forms on Earth are putative fossilized microorganisms found in hydrothermal vent precipitates. The earliest time that life forms first appeared on Earth is at least 3.77 billion years ago, possibly as early as 4.28 billion years, or even 4.41 billion years—not long after the oceans formed 4.5 billion years ago, and after the formation of the Earth 4.54 billion years ago. The earliest direct evidence of life on Earth are microfossils of microorganisms permineralized in 3.465-billion-year-old Australian Apex chert rocks.

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  1. Strato Incendus

    Writing: Input Wanted Can a Gamma-Ray Burst Affect Communication Devices?

    There have been quite a few threads on gamma-ray bursts already, so I’ll make this one as specific as I need it for my WIP sci-fi story: Can a gamma-ray burst that affects the entire solar system, among others, damage the majority (if not all) devices capable of interstellar communication? For...
  2. Z

    Life on Earth -- Which appeared first?

    Which appeared first on Earth, animals or plants? Also, which appeared on land first?
  3. bland

    I Can the multiverse hypothesis be an explanation for life on Earth?

    Specifically he homes in on the multiverse and the 10^500 number that crops up. Basically he ends up saying that the whole concept of the multiverse virtually renders any TOE into pointless oblivion. So with this in mind I was wondering if I could also use the multiverse as an explanation for...
  4. mark!

    I Could life on Earth survive the far future?

    I've read here the following: "Currently, the Moon is moving away from Earth at a rate of 4 cm (1.5 inches) per year. In 50 billion years, if the Earth and Moon are not engulfed by the Sun, they will become tidelocked into a larger, stable orbit, with each showing only one face to the other"...
  5. R

    Factors Promoting Life on Earth

    I seek recommendations and testimonials for books that enumerate the unique factors of the Earth-Moon system that gave rise to life on our planet, its place in the solar system, and the solar system's place in the Milky Way galaxy. If you have read any books on that topic, I would appreciate...
  6. T

    Planetary collision that formed the Moon made life possible on Earth

    https://phys.org/news/2019-01-planetary-collision-moon-life-earth.html The claim is that was how the excess Carbon, Nitrogen, and Sulfur arrived in the Earths crust, without them being in the core. For instance the Carbon/Nitrogen ratio of 40/1 is twice the 'expected' value.
  7. A

    Asteroid Impacts and Life on Earth

    Scientists say when asteroids showered on Earth they were the ones who brought water to Earth which started life. But how did few molecules of water started life on earth?
  8. G

    Could 'aliens' already know there's life on Earth?

    We can indirectly measure the atmospheric composition of worlds outside our solar system. Suppose there are aliens out there. On their world, they use the same technique we use to measure the atmospheric composition of worlds. Suppose they turn their telescope on Earth. Is it possible they...
  9. BillTre

    Evidence for Early Origin of Life on Earth

    Science news reports: (original report abstract here) Eleven micro-fossils though to be the remains of bacteria (some dispute this) from Australia dated to 3.5 billion years ago have been analyzed with secondary ion mass spectrometry (SIMS). This has revealed different ratios of different...
  10. BillTre

    Did Life on Earth Start 3.7 BYA?

    Since the planet is only 4.55 BY old, that might be considered a fast start. Some people have found some rocks (3.7 BYA) in Greenland with what they think are indications of life (short article, a bit longer article). The indicators are primarily microscopic hematite tubes (some say, similar...
  11. L

    Range of Earth's year within habitable zone?

    Hi all, So the (hypothetical) question I have is about the range of the Earth's length of orbit (number of days) within the Sun's habitable zone which could sustain human life. I.e. what would the length of the shortest 'habitable' year be, and the longest (in days)? What would our living...
  12. Dan Allred

    Thought Experiment: How would life on Earth have developed if....

    What would have happened to to the evolutionary process had the Earth's axis of rotation had no tilt? What comes to me first would be a total lack of anything based on the year calendar. There would be no deciduous trees or dormant grasses, certain animal species would have no particular mating...
  13. Greg Bernhardt

    Chemists learn more about how life started on earth?

    Chemists claim to have solved riddle of how life began on Earth http://phys.org/news/2015-03-chemists-riddle-life-began-earth.html Here is the journal article http://www.nature.com/nchem/journal/vaop/ncurrent/full/nchem.2202.html
  14. F

    Multilple origins of life on earth

    From what I understand, all life on Earth is descendent from a common ancestor, which was probably a self replicating molecule that spontaneously formed billions of years ago. As I think I understand it this single molecule self replicated, and succesive generations of the replicated molecules...
  15. I

    Requirements for the origin of life on Earth

    Hi, I'm a physicist with a layman's interest in biology. I was just wondering what the physical requirements for the origin of life on Earth are expected to be. So, for example, pressure range, temperature range, chemicals needed etc. If this has an answer, how confident is the community, or...
  16. A

    Life on Earth: The Future of Humanity and the Impact of Space Exploration

    "Life on Earth, forever?" Well obviously NOT, that looks more like a fairytale. When is the time when 1000 humans have left and have/not returned to the surface, according to the current trend? And, if we consider development, and emerging of new Space-countries, what will be the answer...
  17. nukeman

    Do we know what type of organism first started life on Earth?

    I am not sure on this, so hope someone can shed some light on this. What type of organism was thought to be among the first on earth? I am not sure if this is the right way to ask this :) Lets say if I wanted to see, or do tests on an organism, and my tests were related to doing tests on...
  18. Ivan Seeking

    Is life on earth a one-time event?

    What level of confidence can be assigned to the statement that all life on Earth has one point of origin - a foundation species? Also, is there any evidence that there may have been other genetic lines, other foundation species and their descendents, that did not survive. I am not asserting...
  19. U

    Life on Earth: A 4.5 Billion Year Journey

    They say that all life on Earth is related, now if that's a true statement then it basically means that life has independently started on Earth once in 4.5 billion years. are we really that lucky to be here and if we are then what hope does that give us in our quest to find life on other planets
  20. V

    Probability and Life on earth

    I didn't know exactly the best place to post this, but some intelligent design-minded people have calculated the probability for life on Earth and I just wonder how good there numbers actually are...
  21. B

    How Our Place in the Galaxy Affects Life on Earth

    Something important to think about: If it takes us between 225 and 240 millions years to make one Galaxy orbit wouldn’t it be prudent to associate magnetic polar shift, global warming, and ice-ages to where the sun was located when these events occurred? Were we close to or farther away...
  22. L

    Life on Earth: a Possibility Too Small, or an Undiscovered Law?

    Accorinding to a lot of data and information, it seems that the possibility of producing life is too small. Does it mean that the life on Earth is not formed 'accidentially'? I do not mean that there must be a God (as it is not a religious forum). However, does the too small possiblity means...
  23. R

    What Properties Make Earth Habitable for Life?

    There must be a fundamental property of the Earth that allowed/encouraged life to deveop. Identifying these will help identify other planets that also could contain life. Sorry if this is a repeat thread, I didn't see anything exactly like it. The two more obvious traits are the magnetic...
  24. V

    Why so many people are studying about life on earth ?

    can you tell me why so many people are studying about life on Earth ? Is that funnie or something that is very important ? Thanks Regards
  25. Ivan Seeking

    New Case for Oldest Life on Earth

    http://www.space.com/scienceastronomy/lava_life_040422.html [Broken]
  26. P

    Supernova could wipe out all life on earth ?

    what is the distance at which the explosion of a supernova could wipe out all life on Earth ?