# The Naked Scientists Forum

### Author Topic: How would an anti-gravity belt work in space?  (Read 6697 times)

#### thedoc

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##### How would an anti-gravity belt work in space?
« on: 11/12/2014 03:30:02 »
Fred Richardson  asked the Naked Scientists:

Say I have a functional anti-gravity belt set so that, here on earth, I switch it on and am levitated 1 meter. On the moon I get approximately 6 meters elevation.

So then I go to a rotating space station similar in design to that depicted in '2001 A space odyssey',where the rotation gives me my earthbound mass,  and switch it on... I'm sure Einstein said that mass and acceleration are indistinguishable, but are they interoperable? Can you walk me through this please?

What do you think?
« Last Edit: 11/12/2014 03:30:02 by _system »

#### syhprum

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##### Re: How would an anti-gravity belt work in space?
« Reply #1 on: 11/12/2014 11:49:23 »
Why do you think that you would float at a height of 1 meter ? if the belt annulled the Earths attraction you would float at an in determined  height unless there was some servo mechanism that was controlling your height.
If there was no auto height control you would end up leaving the Earth!
« Last Edit: 11/12/2014 14:05:43 by syhprum »

#### CliffordK

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##### Re: How would an anti-gravity belt work in space?
« Reply #2 on: 11/12/2014 13:15:47 »
There is magnetic levitation.  And, the human body is weakly diamagnetic, so theoretically if a person is put in a strong enough magnetic field, then one could be levitated, and would float, even without "magnetic boots".

One would probably have to be within the magnetic field, not simply on top of it to get enough power.

The power of a magnetic field decreases with the square of the distance, so the Earth to Moon ration would not be 6:1, but would be less.

Your rotating space station would be similar.  However, since centrifugal force would vary with the distance from the center, your levitation field would not be uniform.

#### syhprum

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##### Re: How would an anti-gravity belt work in space?
« Reply #3 on: 11/12/2014 14:11:35 »
Although the magnetic would no doubt work it would be rather inconvenient having to lug around a large 20T magnet and having to keep clear of any magnetisable metal objects, I think I will wait for the belt to be developed.

#### PmbPhy

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##### Re: How would an anti-gravity belt work in space?
« Reply #4 on: 11/12/2014 15:32:29 »
There are two ways that I can think of for an anti-gravity belt to work.

1) One way would be to have negative mass and to set the magnitude of the value of the mass to the same as yours. It would then have a net mass of zero.

2) Another way would be for the belt to act so as to reduce your inertial and gravitational mass to zero after which the body would float. However if you did this to a person then there'd be problems because the chemical makeup of the body depends on the correct value of your electrons and protons having normal mass.

#### syhprum

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##### Re: How would an anti-gravity belt work in space?
« Reply #5 on: 11/12/2014 21:17:00 »
It is well known how antimatter interacts with normal matter but is anything known as to how negative mass would interact with positive matter and for an anti gravity device would there be any problem keeping them separate.

#### syhprum

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##### Re: How would an anti-gravity belt work in space?
« Reply #6 on: 11/12/2014 21:42:00 »
It takes a body of 6*10^24 Kg to pull my 85Kg down to the ground would it not take a similar mass of negative mass materiel to pull me in the opposite direction ? or could this problem be overcome if it was of black hole density and could be much closer to me.
I foresee problems with hawking radiation and spaghettification.

#### PmbPhy

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##### Re: How would an anti-gravity belt work in space?
« Reply #7 on: 11/12/2014 21:52:13 »
Quote from: syhprum
It is well known how antimatter interacts with normal matter but is anything known as to how negative mass would interact with positive matter and for an anti gravity device would there be any problem keeping them separate.
Since negative mass as never been observed we don't know what would actually happen. However Herman Bondi wrote a paper about negative mass and theorizes about it. I can upload it only my website if you want to read it.

#### JohnDuffield

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##### Re: How would an anti-gravity belt work in space?
« Reply #8 on: 11/12/2014 22:42:52 »
Quote from: Fred Richardson
Say I have a functional anti-gravity belt set so that, here on earth, I switch it on and am levitated 1 meter. On the moon I get approximately 6 meters elevation.
There's a bit of an issue here already. If you switch on the device, it's going to create a gravitational field above you that opposes and counters the Earth's gravitational field. If it exactly counters it, you float weightless. If it more than counters it, you rise. To rise 1m it has to more than counter it, then detect that you've risen a metre, then dial itself down so that you float.

Quote from: Fred Richardson
So then I go to a rotating space station similar in design to that depicted in '2001 A space odyssey',where the rotation gives me my earthbound mass,  and switch it on... I'm sure Einstein said that mass and acceleration are indistinguishable, but are they interoperable? Can you walk me through this please?

The whole point of all this is that the principle of equivalence is only a principle. Accelerating through space is like being in planetary gravitational field, but it isn't exactly the same. In the former situation the energy density of space is uniform, but your energy is increasing. In the latter situation the energy density of space isn't uniform, and your energy isn't increasing.
« Last Edit: 11/12/2014 22:50:43 by JohnDuffield »

#### yor_on

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##### Re: How would an anti-gravity belt work in space?
« Reply #9 on: 13/12/2014 20:06:42 »
Wish I knew :)

You want a statement of faith? Yeah, they are inseparable to me. Because i do not buy the idea of 'particles' kissing 'particles'. I expect to make me uncomfortable in a world where everything should be reduced to 'forces', acting at forces' acting, add infinity.

We're more than that.

#### yor_on

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##### Re: How would an anti-gravity belt work in space?
« Reply #10 on: 13/12/2014 20:09:54 »
Stop defining gravity of two signs please :)
Gravity is what allows you to wonder.

#### syhprum

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##### Re: How would an anti-gravity belt work in space?
« Reply #11 on: 15/12/2014 20:57:35 »
I seem to have confused myself somewhat the body of anti mass materiel would not have to be above pulling me up ordinary materiel such as that of which our moon is made will suffice for that if the spacing is correct.
If I wish to use anti matter materiel to push me up against the Earths pull it must be below me.
This poses  problems if I try to bury it in a deep shaft it will surely be ejected.

#### PmbPhy

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##### Re: How would an anti-gravity belt work in space?
« Reply #12 on: 15/12/2014 21:45:55 »
Quote from: yor_on
Stop defining gravity of two signs please :)
Why?

In any case we're not defining it since that's already been done and published. We're merely discussing it.

#### JohnDuffield

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##### Re: How would an anti-gravity belt work in space?
« Reply #13 on: 16/12/2014 21:29:44 »
I seem to have confused myself somewhat the body of anti mass materiel would not have to be above pulling me up ordinary materiel such as that of which our moon is made will suffice for that if the spacing is correct.
That's right. It's not some magical mysterious anti-gravity generator, it's just a boring old gravitational field generator. I know we said belt, but you generate the field above your head so that it cancels out the Earth's field.

#### PmbPhy

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##### Re: How would an anti-gravity belt work in space?
« Reply #14 on: 17/12/2014 00:16:07 »
Quote from: syhprum
I seem to have confused myself somewhat the body of anti mass materiel would not have to be above pulling me up ordinary materiel such as that of which our moon is made will suffice for that if the spacing is correct.
If I wish to use anti matter materiel to push me up against the Earths pull it must be below me.
This poses  problems if I try to bury it in a deep shaft it will surely be ejected.

If you wish to cancel the gravitational field in a region of space then all you need to do is distribute mass in the surrounding space in the appropriate locations so as to have a net field in the region of interest of zero.

That's why the gravitational field inside a spherical shell is zero, i.e. because for each element of matter on one point on the surface of the sphere is counteracted by matter on the other side of the shell.

A trivial example is that of two point particles having the same mass. To see the potential diagram for points along a line connecting the two particles please see the figure I created. It's at the bottom of the following web page in Figure 1: http://home.comcast.net/~peter.m.brown/gr/grav_field.htm

There is one and only one point at which the field is zero and that's at the mid point between the two point particles.

#### syhprum

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##### Re: How would an anti-gravity belt work in space?
« Reply #15 on: 17/12/2014 16:57:28 »
The problem with gravity is that you need such a large mass to generate any appreciable field, if I wished to counter balance the pull of the Earth assuming it is a point mass 6441 Km away by a point mass 1 Km away it would need to be a mass of approximately 1.4396*10^17 Kg and the size the space of quasi zero gravity zone would be very small and one could easily zoom off to the closer mass.
I don't see we are going to get anti gravity belts any time soon.
« Last Edit: 17/12/2014 17:03:05 by syhprum »

#### yor_on

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##### Re: How would an anti-gravity belt work in space?
« Reply #16 on: 02/01/2015 16:41:24 »
Pete, are you telling me that Einstein defined gravity as being of two signs? As far as I've read he gave it only one sign. 'Attractive', doesn't matter what frame of reference you choose for it?

You need references for that one I think.
=

It might be that you're thinking of him defining it as something, a object, 'attracting' as well as it finding itself 'attracted'? That's not what I'm discussing. I have only one definition, and that one is of a ideal 'sphere' of rest mass attracting.  doesn't really matter to me, for that one, if one would introduce another mass, 'attracting' the first. Give me a vacuum, introduce a mass. Which is just speculation naturally :)
« Last Edit: 02/01/2015 16:50:38 by yor_on »

#### The Naked Scientists Forum

##### Re: How would an anti-gravity belt work in space?
« Reply #16 on: 02/01/2015 16:41:24 »