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Gravity Creation Idea (don't assume troll)



 
 
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  #1  
Old March 4th 05, 07:06 PM
Matthew Hagston
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Default Gravity Creation Idea (don't assume troll)

There's an idea that's been going through my head dealing with creating
artificial gravity, before you think troll just stay with me here. It deals
with two of Einstein's papers; the first stating as an object speed
accelerates closer towards the speed of light, it's mass increases, the
second states mass is directly related to gravity. So Take an object like a
large super-conductive disk, inside a vacuum to reduce friction, and spin
it. If you can make it spin fast enough (up towards the speed of light) you
should be able to create gravity with out having the real mass required.
Creating a sort of virtual mass so to speak.

I realize there must be something wrong with my logic because this seems
like such a simple solution, so I invite some criticism here.

--
Matthew Hagston
Hungates Creative Toys and Hobbies
........ http://www.hungates.com


  #2  
Old March 4th 05, 07:47 PM
Allen Thomson
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Matthew Hagston wrote:

If you can make it spin fast enough (up towards
the speed of light) you should be able to create
gravity with out having the real mass required.
Creating a sort of virtual mass so to speak.


I realize there must be something wrong with my logic because
this seemslike such a simple solution, so I invite some
criticism here.


It would work, but there are certain engineering difficulties
associated with spinning a material disk fast enough that the
apparent mass per unit area would be large enough. Also,
there would be a gravity gradient from middle to rim that
might be troublesome. Also also, you really wouldn't want
to have an accident with the thing.

Maybe what you need is a *very* high-current, high-energy cyclotron.
You wouldn't want to have an accident with that either.

  #3  
Old March 4th 05, 07:48 PM
Christopher M. Jones
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Matthew Hagston wrote:
There's an idea that's been going through my head dealing with creating
artificial gravity, before you think troll just stay with me here. It deals
with two of Einstein's papers; the first stating as an object speed
accelerates closer towards the speed of light, it's mass increases, the
second states mass is directly related to gravity. So Take an object like a
large super-conductive disk, inside a vacuum to reduce friction, and spin
it. If you can make it spin fast enough (up towards the speed of light) you
should be able to create gravity with out having the real mass required.
Creating a sort of virtual mass so to speak.

I realize there must be something wrong with my logic because this seems
like such a simple solution, so I invite some criticism here.


It would work, to a degree depending on the strength of the
disk, but you gain nothing. Remember E=mc^2, mass and energy
are two sides of the same coin. When you create a
"mass-energy" in a rapidly spinning disk that mass is no
different than any other mass. Moreover, the energy you use
to spin up the disk is no different than any other mass. In
order to spin up a disk fast enough to increase it's mass by,
say, 1kg, you need to input 1kg of mass/energy, period.
Using your method that would require harnessing 1kg of energy,
90 petajoules!, transporting it to the vicinity of the disk,
and then applying the energy to spin up the disk. It would
be quite a lot more direct to simply transport a 1kg mass, as
the result is exactly the same without the inefficiencies and
incredible difficulties. Additionally, to generate 1 gee of
gravity through this method would require a mass/energy on
the order of that of the Earth.
  #4  
Old March 4th 05, 09:01 PM
Eric Chomko
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Matthew Hagston ) wrote:
: There's an idea that's been going through my head dealing with creating
: artificial gravity, before you think troll just stay with me here. It deals
: with two of Einstein's papers; the first stating as an object speed
: accelerates closer towards the speed of light, it's mass increases, the
: second states mass is directly related to gravity. So Take an object like a
: large super-conductive disk, inside a vacuum to reduce friction, and spin
: it. If you can make it spin fast enough (up towards the speed of light) you
: should be able to create gravity with out having the real mass required.
: Creating a sort of virtual mass so to speak.

: I realize there must be something wrong with my logic because this seems
: like such a simple solution, so I invite some criticism here.

I'm no physicist, but don't molecules have trouble staying together in
cyclotron-like environments? IOW, everything to date that we can manage
accelerate is of a sub-molecular level. What good is creating gravity for
elements with no way of retaining any molecular form?

And your object, the super-conductive disk; where can I buy one?

Eric

: --
: Matthew Hagston
: Hungates Creative Toys and Hobbies
: ........ http://www.hungates.com


  #5  
Old March 4th 05, 09:10 PM
Henry Spencer
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In article ,
Christopher M. Jones wrote:
...Additionally, to generate 1 gee of
gravity through this method would require a mass/energy on
the order of that of the Earth.


No, only if you insist on having 1G at a distance of some 6400km. At
one-millionth the distance, you need one-trillionth (10^-12) the mass.
Still kind of a lot, mind you...
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |
  #6  
Old March 4th 05, 10:50 PM
Tom Kent
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"Matthew Hagston" wrote in
nk.net:

There's an idea that's been going through my head dealing with
creating artificial gravity, before you think troll just stay with me
here. It deals with two of Einstein's papers; the first stating as an
object speed accelerates closer towards the speed of light, it's mass
increases, the second states mass is directly related to gravity. So
Take an object like a large super-conductive disk, inside a vacuum to
reduce friction, and spin it. If you can make it spin fast enough (up
towards the speed of light) you should be able to create gravity with
out having the real mass required. Creating a sort of virtual mass so
to speak.

I realize there must be something wrong with my logic because this
seems like such a simple solution, so I invite some criticism here.


I'm afriad the disk would fly apart due to overwhelming centripital forces
far before anything relavistic was achieved. There just aren't materials
with that kind of tensile strength :-(

Tom
  #7  
Old March 4th 05, 10:56 PM
Christopher M. Jones
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Henry Spencer wrote:
In article ,
Christopher M. Jones wrote:

...Additionally, to generate 1 gee of
gravity through this method would require a mass/energy on
the order of that of the Earth.


No, only if you insist on having 1G at a distance of some 6400km. At
one-millionth the distance, you need one-trillionth (10^-12) the mass.
Still kind of a lot, mind you...


I already thought of that. The problem is one of
density. Realistically, you can't get convenient
chunks of matter that are denser than about 18 g/cm^3
(e.g. Uranium). This is not all that much more
than the average density of Earth (about 5 g/cm^3).
Disregarding compression, to achieve 9.8 m/s^2 of
gravity on the surface you would need a spherical
mass approximately 1,948 km in radius, weighing
about half a billion trillion tonnes (5.6e23 kg).
Certainly that's a factor of ten off the mass of
the Earth, but it's still a tad much.

You could get away with a lot less mass if you had
extremely dense materials (neutronium, strange
matter), but being able to build structures using
such materials is speculative at this point.
  #8  
Old March 4th 05, 11:01 PM
Matthew Hagston
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"Christopher M. Jones" wrote in message
...
Henry Spencer wrote:
In article ,
Christopher M. Jones wrote:

...Additionally, to generate 1 gee of
gravity through this method would require a mass/energy on
the order of that of the Earth.


No, only if you insist on having 1G at a distance of some 6400km. At
one-millionth the distance, you need one-trillionth (10^-12) the mass.
Still kind of a lot, mind you...


I already thought of that. The problem is one of
density. Realistically, you can't get convenient
chunks of matter that are denser than about 18 g/cm^3
(e.g. Uranium). This is not all that much more
than the average density of Earth (about 5 g/cm^3).
Disregarding compression, to achieve 9.8 m/s^2 of
gravity on the surface you would need a spherical
mass approximately 1,948 km in radius, weighing
about half a billion trillion tonnes (5.6e23 kg).
Certainly that's a factor of ten off the mass of
the Earth, but it's still a tad much.

You could get away with a lot less mass if you had
extremely dense materials (neutronium, strange
matter), but being able to build structures using
such materials is speculative at this point.


The faster you could 'spin' it (get it closer to the speed of light). The
less mass you would need to start with though right?
--
Matthew Hagston


  #9  
Old March 4th 05, 11:40 PM
Christopher M. Jones
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Matthew Hagston wrote:
The faster you could 'spin' it (get it closer to the speed of light). The
less mass you would need to start with though right?


The only advantage this gives you is in density. In
all other aspects this scheme is dramatically more
difficult than just using a pile of matter. And it
is insanely more difficult and cumbersome than just
using acceleration (e.g. rotation). Unfortunately,
even that benefit is very tiny and almost
inconsequential. The problem is that ordinary matter,
even diamond or buckytubes, is just not strong enough
to store enough rotational energy to significantly
affect its mass. Consider that the maximum amount of
energy storable via this method is similar to the
energy stored in the chemical bonds of the material,
and that energy is similar in degree to the energy
released by chemical explosives. Now compare that to
the energy density of matter and the amount of energy
released by just a tiny amount of matter (e.g. much
less than 1% of the mass in the case of fission or
fusion explosions, 100% in the case of anti-matter,
matter annihilations).

Even given all that (namely, the ability to store
on the order of 20 *megatons* (TNT equiv.) of energy
per kg) you would have improved the mass/energy
density by a mere factor of 2, if that. Most likely
though, since you would be forced to use materials
with strong covalent bonds (e.g. carbon compounds)
you would start out at a relative disadvantage in
terms of density compared to using the densest
matterials avaible (e.g. Lead, Uranium). So you
would gain no advantage at all.
  #10  
Old March 5th 05, 12:29 AM
Henry Spencer
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In article ,
Christopher M. Jones wrote:
No, only if you insist on having 1G at a distance of some 6400km. At
one-millionth the distance, you need one-trillionth (10^-12) the mass.
Still kind of a lot, mind you...


I already thought of that. The problem is one of
density. Realistically, you can't get convenient
chunks of matter that are denser than about 18 g/cm^3
(e.g. Uranium).


Remember, the whole point of the question that started this particular
thread is (essentially) that "mass" and "matter" are not the same thing.
Energy too has mass, and the mass of the hypothetical disk with the
relativistic spin is dominated by its energy content, not its matter
content. That is, its density at rest is basically irrelevant.

What *is* relevant, alas, is the impossibly high structural strength it
requires. With the strongest materials we've got, flywheel energy storage
struggles to be competitive with batteries. This falls many orders of
magnitude short of what's needed to store significant *masses* of energy.
There is room for improvement in the materials, notably with the nanotube
composites that many people are trying to make, but that's about one order
of magnitude, which is nowhere near enough.

Plus, as others have pointed out, transporting such vast amounts of energy
is much harder than transporting equivalent amounts of matter. The entire
energy output of the Sun is only about four million tons per second.
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |
 




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