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Dark Energy and Life?

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  1. Jul 25, 2013 #1

    Nugso

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    Hi everyone. I wonder if life and dark energy have something in common or are related to each other. If our universe had more dark energy than it now has, e.g 90% of the universe was filled with dark energy, would we still be able to live? The more dark energy, the fewer the chances of us being alive?
     
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  3. Jul 25, 2013 #2

    Drakkith

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    There is no relation. More dark energy would simply cause more acceleration of the expansion of the universe. Less would cause less. While a different amount of dark energy could cause vast changes in the evolution of the universe as a whole, for life itself it has little impact.
     
  4. Jul 25, 2013 #3

    Nugso

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    If there was more dark energy, we would have less energy which means either living-beings would have to consume/use less energy or there would have to be fewer people. Is my logic invalid?

    Thanks.
     
  5. Jul 25, 2013 #4

    Drakkith

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    Hmm.

    First, if we magically add more dark energy to the universe, that doesn't mean that we take away from somewhere else. At least that's not what you said in your first post.

    Second, if it did require a reduction of energy in the form of dark matter or normal matter, which is what remains after dark energy, what would be the consequences? Is the Earth even still here? Does it have the same mass? How about the Sun? The number of possible changes that could cause the Earth to be completely uninhabitable is nearly infinite.
     
  6. Jul 25, 2013 #5

    Nugso

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    My apologizes. Well considering the universe are made of matter, dark matter and dark energy, I thought I could safely say in order for dark energy to be more, the others has to be less. Also it's a matter of chance then, right? All the livings being might die or not. We can't be sure of it?

    As for your second question; I really don't know. That's why I come up with the thread. Also sorry for being off-topic, when we say "energy", what do we mean by it? I mean in which category above does it belong to? Matter? Dark Matter? Dark Energy?

    I guess it's matter because energy is form of a matter. Right?


    Thanks very much by the way.
     
  7. Jul 25, 2013 #6

    Drakkith

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    Sure, PROPORTIONALLY. But not in absolute values. If you just magically add more dark matter, that doesn't mean that there must be less dark energy and normal matter. The ratios have changed, but the amount of normal matter still remains the same.

    I wouldn't say chance. I'd say we would need to pin down exactly what would happen if we reduced the amount of dark matter and normal matter at the beginning of the universe.


    To get specific, energy is defined as the ability to perform work. For example, a baseball being thrown towards a batter has energy in the form of kinetic energy. If the batter misses the ball will perform work on the catcher when it impacts his mitt. There are many different types of energy, but all of them boil down to the ability for one system to perform work on another.

    Thus, dark matter has energy in the form of kinetic energy and gravitational potential energy. Normal matter has this same energy in addition to a few others that dark matter does not since normal matter interacts via the other 3 fundamental forces of nature in addition to gravitation. (Forces give rise to energy, not the other way around)

    Dark energy is a little different, but I'm not sure how. I just don't know enough about it.
    I can say that many scientists believe that there is no such thing as dark energy and that the accelerating expansion of the universe is being driven by some sort of constant or something else to do with geometry. (Because General Relativity, which is what we use to model the universe with, is a theory of Geometry)
     
  8. Jul 25, 2013 #7
    I'm not sure sure about that...more dark energy could mean that interstellar gas, for example, would never coalesce to form suns, planets,etc....or form far more slowly....or maybe run away inflation...who knows what?? Nobody.

    Considering how so many things seem 'fined tuned' I'd be inclined to guess there could be substantial effects. In any case nobody even knows what dark energy is or if it even exists as 'energy'..so maybe we better wait for some more knowledge.,,like whether it can be determined it is a constant energy [ala the cosmological constant] or a scalar field.
     
  9. Jul 25, 2013 #8

    Drakkith

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    Which was exactly my point. If you just magically put more dark energy in the universe right now, life would remain unaffected. However, if you change the amounts at the creation of the universe as we know it, then things change drastically.
     
  10. Jul 25, 2013 #9

    Nugso

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    Didn't know dark matter has only potential and kinetic energy. So dark matters can't heat up. Sounds interesting.

    How about the difference(s) between dark energy and normal energy as we define today?

    Thanks.
     
  11. Jul 27, 2013 #10

    Dale

    Staff: Mentor

    closed pending moderation
     
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