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Any physicists out there? Please explain this to me... Watch

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    The existence of a force of gravity is a pervasive false believe.

    When you hold your arm out horizontally, and think you are feeling it being pulled downwards by a force of gravity, the only force you are actually feeling is the upward force exerted by your own muscles in order to keep your arm accelerating continuously away from a straight path in spacetime. Even today, it is hard to discipline our intuition to conceive of what is happening in that way, but it really is.


    Not sure I geddit
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    I think I know whats its trying to say. It's like when you're standing up. You are not actually feeling gravity pull you down but the reaction force of the floor you are standing on.
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    so what we think of as gravity doesnt actually exist?
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    http://en.wikipedia.org/wiki/Introdu...ral_relativity
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    can someone explain what a "straight path in spacetime" is?

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    We don't really understand Gravity anywhere as much as the other fundamental forces, and it's incompatible with alot of theories intended to unify all the forces, in particular a lot of quantum mechanics does not work with gravity.
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    ..
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    From what I understand, Gravity is pulling you down towards the centre of earth. Gravity causes an acceleration of 9.8 ms^-2 towards the centre of the earth so your body has to react against this in order to meet this acceleration. So, when you hold your arm out straight, you are accelerating against gravity. It is this acceleration of your arm and the act of holding up the weight of your arm that you feel.

    The "straight path in spacetime" bit doesn't make much sense. I can only guess it means a straight path towards the centre of gravity of the earth (ignoring anything in the way).
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    Gravity is just the effect objects with mass have on the fabric of space time. Anything with mass warps spacetime around it, causing other objects to follow these 'creases' in spacetime or whatever towards the object.
 
 
 
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