Why is it so hard to build gravitational shield?Angels55 - 6 Answers
Gravity is believed to have no fundamnetal particle (boson) that carries the force itself (such as ?virtual? photons in the case of electromagnetism, which you mentioned). No matter how you approach the problem, the General theory of Relativity provides the inevitable conclusion that gravity is the only one of the four fundamental forces, which doesn't involve some type of fundamental particle to facilitate the propagation of the force itself (although a quantum physicist might argue for the involvement of the so called "graviton" ad nauseum - in the absence of proof, let alone a viable theory, it's simply not science!). Gravitational fields are a property inherent of spacetime itself, more specifically described as the warping or distortion of the fabric of spacetime by the presence of mass at a location. As such, the force of gravitational attraction (free-fall) which is experienced between two (or more) of these local spacetime distortions by massive entities in normal otherwise normal "homogenous" spacetime, which is how we always perceive it, is clearly not mediated by anything other than the "fabric" of spacetime itself. This is why gravity is considered to be exclusively an attractive force between two objects that have mass, not a pair of opposite forces that attract or repel depending on their charge or sign. Gravitational fields are produced with perfect symmetry in all directions (assuming the underlying spacetime is homogenous and isometric), tapering off quickly (as the the inverse of the square of the radius), but asymptotic to zero. In other words, theoretically, no matter how ?negligible? it's influence at a given distance, gravity's effects are infinite in reach (although they only propagate through space at luminal to subluminal speed). Gravity is clearly unique among the four fundamental forces of our universe.
Negative mass would be one exotic source of gravitational shielding, or so one might hypothesize. But the repulsive effect would make it difficult to practically implement (assuming it was real known quality that a particle could posses, and we did discover it one day in the future)! Since there's no other way that I can think of to ?anti-warp? spacetime, or warp it in the negative direction locally, I can only resort to separation shields involving a man-made temporary, isolated sphere of spacetime, where our universe should have no effect inside such a ?bubble?. But this assumes we could ?reunite? such a creation with our own universe when necessary! A satellite might give the appearance at being ?shielded? from a particular gravitational source, however this is not a truly shielding gravity, just as close as we might hope for in the near future.
At the quantum order of magnitude it's difficult to say what is or isn't possible with gravity, since classical relativity does not properly predict the interactions of particles at this level (especially at high speeds). So until this problem has somehow been resolved one can't rule out a gravitational shield at this level, however in the same vain, there is no real underlying theoretical basis for which to design such a shield either. We are unlikely to guess one into existence!
To the remark someone made about the mysterious rope between two people that supposedly has no force applied to it, try to exceed the tensile strength of the rope and you will see the force released quite quickly! Scissors work just as well. Why else would the two people pulling against one another ever tire?
As to General relativity - gravity is the cause of spacetime distortions AND spacetime distortions are the cause of gravity between two masses. The former might describe a universe with a single mass, although the space time distortion would still be present it would have no real function (that we know of at least!).
Thanks for your interesting question!
Osolooo is trying to answer this on the basics of Physics. As long as you have equal forces in opposite directions there is no force at all, so it would be theoretically like in a Vacuum.
For example if you have a rope which one person pulls to the left and an other person to the right and both have the same strenght the rope is affected by no force at all.
Yet we cannot build a device which could equal Gravity because Gravity has no real direction, because Gravity goes always towards the Earth Core. So you would need a device which creates Gravity with 9,81 m/sÂ² (Standard for calculations, but you would need to calculate the local Gravity) in the opposite direction of the gravity.
Yet there is an other way to simulate this which people love to do within facilities. To save explaination here are some links to pictures:
This is pretty much some kind of how to make a "Gravitational Shield" Yet not really the solution... Anyways in Theory it is easy to make a Gravitational Shield, in practical ways it is not. The biggest reason is like I wrote in my first Answer that we cannot create any artifical Gravity which we could force against the Gravity which comes from the Earth Core.
But if we could do that, then we could shield ourselves from Gravity.
Edit: It is because I learned the Physics and such in German and to translate the specific words is very hard and the complex stuff how everything works.
The biggest problem to "shield" against Gravitation may be that it is no radiation. And that Gravity is based on Rotation and Masses of different objects. Also it affects everything around.
For Example is the center of our solar system the Celestial Body "Sol" or how we may call it in english "Sun" it has such a big mass that the planets are moving in an elipse around it. Yet every Celestial Body moves in a different way around it. The Mercury is the closest and so the strongest affected one.
Mars, Neptune, Venus and of course "our" Earth is affected by the gravity of the Sun. Yet the Sun also affects the moon, but because the moon is closer to the Earth, the moon is affected stronger by the Earth.
And we may be not able to shield ourselves from gravity yet... But we can create Artifical Gravity through Rotation. The faster an object rotates, the stronger the gravitation within the object is. You may have seen that effect on a "Centrifuge" for the training of Astronauts.
Even the first Space Colonies' ideas are based on rotation. Yet the bigger we make an object, the slower it would had to move around it's own Axis.
So to build a "gravitational Shield" it may take us decades, centuries or probably even milleniums. Because we cannot create "Anti-Gravity" to let objects really levitate. Neither can we increase the Gravity in a specific area. So before we may shield us from Gravity we have to study it a very long time further.
If you have a rope with one person pulling at one end and another at the other end, each pulling in opposite directions, the rope would experience a tension and would be affected by the forces.
Does General Relativity explain anything? Is gravity the cause of space-time distortions, or are space-time distortions the cause of gravity? Or is there any connection at all?
We can easily shield electric fields and electromagnetic radiation with conducting wall on a room. Does this make any difference in your thinking, or does it make your knife-like thinking come to a sharper edge?
From my understanding the reason it is so hard to shield against gravity is the fact that we do not fully understand how gravity works. If we knew more about it we might be able to come up with a way to shield against it....
Because the sheild itself will have equal gravity to the force you are trying to shield against....