# What would the effects of an anti-grav device be?

**URL:** <https://boards.straightdope.com/t/what-would-the-effects-of-an-anti-grav-device-be/712745>\
**Category:** Factual Questions\
**Created:** [February 15, 2015, 8:22pm UTC](https://boards.straightdope.com/t/what-would-the-effects-of-an-anti-grav-device-be/712745 "2015-02-15T20:22:26Z")\
**Posts on this page:** 2\
**Page:** 2

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**Author:** ![dracoi](https://avatars.discourse-cdn.com/v4/letter/d/90db22/32.png) [@dracoi](https://boards.straightdope.com/u/dracoi)\
**Post date:** [February 17, 2015, 6:59pm UTC](https://boards.straightdope.com/t/what-would-the-effects-of-an-anti-grav-device-be/712745/21 "2015-02-17T18:59:28Z")

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> [@newme](#):
>
> Congratulations! You have just invented a perpetual motion machine. Position a vertically mounted wheel such that half of the wheel is in the anti-grav field and half is outside. Gravity will pull down on the half outside the field, causing it to rotate, since the other half is now weightless. Attach a generator to the axle and you have solved the energy problem.

It’s not necessarily a perpetual motion machine. If the anti-gravity mechanism requires a larger energy input than you could get out of the wheel, you’d at least be keeping up with the laws of conservation of energy. It would only be perpetual motion if your anti-grav device required less energy than the wheel generated.

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**Author:** ![Hail\_Ants](https://avatars.discourse-cdn.com/v4/letter/h/dc4da7/32.png) [@Hail\_Ants](https://boards.straightdope.com/u/Hail_Ants)\
**Post date:** [February 18, 2015, 4:20am UTC](https://boards.straightdope.com/t/what-would-the-effects-of-an-anti-grav-device-be/712745/22 "2015-02-18T04:20:30Z")

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> [@The\_Joker\_and\_the\_Thief](#):
>
> This is exactly as meaningful as asking for the resting pulse rate of a unicorn. Such a device couldn’t exist, so any details someone thinks up are just illusory and impossible to prove.
> 
> I don’t like raining on parades, but sometimes its the only response.

Well, it certainly can’t exist until we figure out how/why gravity functions as a fundamental force…

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