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Sensitivity to G

  1. Jan 27, 2013 #1
    How sensitive are animals, specifically humans, to changes in gravity that influence their body?

    I am not talking about changes that a human would feel in a variable centrifuge.

    The thought experiment would be:

    1. A person is sat on a chair or reclined on a sofa.
    2. Adjacent is a dividing wall through which the person cannot see, smell, taste, touch or hear (no vibrations, magnetic fields & RF shielded)
    3. On the other side of the wall a large mass is in motion.
    4. Would the person detect (un)consciously the changes?
  2. jcsd
  3. Jan 27, 2013 #2

    Simon Bridge

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    Welcome to PF;
    A human Cavendish experiment aye?

    Depends on the size of "large".
    But the short answer would be "no" for any mass small enough to move about without the subject noticing. You can work out the size of the effect from Newton's law of gravitation.

    Another way to do the experiment is to put the subject and sofa in a soundproof box and tip it (or accelerate it) to find out the smallest change in acceleration that the subject can detect. Note: there is no difference between accelerating and changing gravity.
  4. Jan 27, 2013 #3

    Andy Resnick

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    There are a *lot* of changes that occur, which we have learned from decades of access to the microgravity environment. Acutely, humans experience bone loss, suppression of the immune system, re-distribution of body fluids (especially impacting the sinus cavities), and more. While the mechanisms for some of these are obvious (e.g. fluid changes due to loss of orthostatic pressure gradient), not all are.

    There have also been (non-human) experiments showing up- and down-regulation of dozens of genes. I can check my reference materials shortly, but I don't think there have been any meaningful sensitivity studies.
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