# Quantum anti-gravity?

Am I reading some more recent articles on quantum gravity correctly that seem to be implying that a coherent particle is not subject to gravity?

If you have a coherent C70 buckyball molecule (see Zeilinger - Update: "Matter-wave interferometer for large molecules", Jan. 2002), the force of gravity will not apply to it and it can float in zero gravity as long as it remains coherent (in relation to the source of the gravity field).

This makes lots of intuitive sense to me. If a coherent buckyball was subject to gravity, would it not be possible to detect the particle's gravity field by ultra sensitive instruments (without decohering the buckyball), and hence in a double slit experiment, we can observe which slit the particle travels though, without having to measure it, and hence the particle cannot be coherent - a contradiction?

This can be easily tested. Just pass the coherent buck balls horizontally through a single pinhole and let it decohere on a screen that is far away. Find the center of the distribution and measure it with respect to the straight line trajectory. If the center of distribution weighs downward, then the bucky ball was subject to gravity. But if it remains at the trajectory, then the buckyball was not subject to gravity.

Another test is to shoot the buckyballs vertically against the gravitational field. If the particle is subject to gravity, and if the decohering screen is far enough, then you will not see a distribution pattern. If you see the pattern, then the buckyballs were not subject to gravity.

You would ask, if a buckyball is not subject to gravity, it can gain potential energy by floating upwards without expending energy, hence a contradiction. Now, when a particle or a system decoheres (collapses), it emits energy. If the particle while coherent floats upward, then it will emit less energy upon decoherence. If it floats towards the earth, it will emit more energy. If it floats against the gravitational field far enough, you would actually need to expend energy to get the particle to decohere. Which is interesting. It would mean the coherent particle would have a tendency to remain coherent, and not to decohere so readily. The particle would remain undetectable until the measuring instrument can supply the extra energy needed to decohere it. If the screen is cold enough and can convey no thermal energy, then the buckyball will hit the screen but not decohere (or collapse)? This way it would be very easy to keep particles in a coherent state.

In some sense, the act of coherence, puts the particle in an extra dimension, where gravitational fields (electric fields? magnetic fields?) do not apply.

Question arises: How do you supply the extra energy you need to decohere a bucky ball that has traveled against the gravitational field, and you have little idea where it will decohere?

Now if you could make a cat coherent (including life support), then you could send it to the moon, with next to none energy used here on earth, but a lot of energy used on the moon to receive the cat.

Imagine a coherent entangled pair. One remains on earth and the other travels against the gravitational field. Then in order to decohere the particle on earth, a lot of energy must be used. Hence the particle on earth will tend to remain coherent, and not decohere so readily.

I apologize in advance for this rambling as it must be physically incorrect.

Last edited:

• 