Is it true that there is a gravitational field everywhere in the known universe?

Question

Secondary question: Has anyone ever invented a "gravitational shield"? I am not talking about anti-matter, nor anti-gravity, nor levitation. It is possible to build a "Faraday cage" to exclude all electromagnetic fields, but I want to know whether it is possible to build the equivalent for gravitational fields. All opinions are welcome.

Answer 1

According to Newtonian gravity, gravitational force is -GMm/r^2. Any mass experiences a gravitational force toward every other mass in the universe, proportional to the product of their masses, and inversely proportional to the square of their distance. This means my body experiences a certain gravitational force from the sun, no matter what else is happening in the universe. That says it would be impossible to shield me from the sun's gravity.



To find the net gravitational force on me, simply do a vector sum of all the gravitational forces on me from all other masses in the universe. Simple to say, not so simple to do.



That sum is zero at the center of mass of the universe, wherever that is. Unless the expansion of the universe is perfectly uniform, that point will shift with time. I could find other points where the sum is zero. I move away from that center of mass but toward a large nearby mass, just close enough that the pull of that nearby mass exactly balances the pull of the rest of the universe. These will be single points, not regions. At these points, I still can't say there's no gravitational force acting on me. But I can say there are countless gravitational forces acting on me, but their sum is zero.



Let's say I tell you I found such a zero-sum spot, about 1/3 of the way between our sun and Alpha Centauri, and I take you there. How will you know I am telling you the truth? The principle of equivalence says that there's no test you could make to tell whether the net gravitational force there is zero, or whether you are just accelerating according to the effect of the nonzero net force on your mass.



The relativistic warping of spacetime in the presence of gravitational mass is more a way of representing or measuring that force, rather than explaining it. Neither Newton nor Einstein could tell us why gravity exists or how it works. If spacetime is not warped in your region, it doesn't mean the gravitational field is zero, it means it is uniform. And again, how would you tell whether spacetime is warped in your region?



I've tried for decades to think of a gravity shield or a gravity insulator. If I do find one, watch for my Nobel Prize in physics, and for me to quickly surpass Bill Gates on the wealth scale.

Answer 2

The above answers are Newtonian.



If you look at it from an Einstein point of view (geometrical) then the answer is both easy (and difficult).

Astronomers tell us that the universe is, largely, 'flat'

This means that if I shine a laser at the star to which I am heading then my spacecraft seems to follow in the direction of the light towards the star.



When I come to a curved bit of spacetime and I shine my light I find that my spacecraft does not follow the light!

Both the light and the ship are deflected - but by different amounts. We might say "Aha their is a force acting on us - we'll call it gravity. That is what accounts for the deflection from our chosen path!"



From a Geometrical point of view we are merely travelling through a curved bit of spacetime. The reason we and the light follow different paths is that the two things travel in diferent allocations of space-time and the light appears not to be deflected as much as our 'massive' spaceship is.

BUT the curvature of spacetime is exactly the same for both the light and us.



So simply:

If space-time is flat --------- no Gravity

if spactime is curved-------- wow - we must be in a gravitational field



To answer the Second Part.

We need a machine, like a giant Smoothing Iron, that will flatten space-time out in the curved regions.

Answer 3

Gravity follows an inverse square, so the pull of my little pinky is tugging on distant parts of the universe. Just because you can balance gravity at a Lagrangian point between two bodies does not mean there is no gravity. Try flying out and you find out you were in a gravity well after all. Likewise, free-falling in a gravity well doesn't make the well go away either, just the force you feel.



Regarding shielding, dark energy apparently provides an affect which can neutralize the normal attractive force of gravity, so maybe someday we will understand how to manipulate this beast to at least create locally neutral fields.

Answer 4

There is a gravitational field everywhere, but far enough away from any matter it is weak enough that you can virtually ignore it.



We still aren't completely sure about how gravity works. I think that it would be possible to build some sort of 'anti-gravity' device just like a Faraday cage, but I have no idea how you'd do it.

Answer 5

There can be an area of zero gravitation where the sum of all gravitational fields from all the objects in the universe comes to zero. It is unlikely that such an area exists although theoretically possible; if it does, it is very small. Otherwise, the field exists everywhere even if it is minute.



A freely falling object is in a zero gravitational field.



The laws of the gravitational field are not the same as for electric or magnetic fields, and there is no such thing as gravitational shield.

Answer 6

expensive Sunshine. It warms my soul that you've "continually idea that ability calls for a medium". i'm hoping that once you win the Nobel Prize for contradicting the stunning 100 years of better physics you'll save in ideas me because the purely human being who did not imagine you've been an ignorant crackpot. Please, purely be sensible to stay to inform the tale your meds so that you'll earnings from the praise and accolades of your fantastic success. by ways, have you ever revealed any of your idea yet? Or will that's an element of your PhD thesis? if so, who's your graduate consultant? On a truly a lot less sarcastic be conscious a million) quantum field idea (the most especially shown and proven idea ever created by guy) instantly contradicts you. the field vendors are "quantum" (ie debris) 2) the position TF did you get the concept the vacuum became empty? the vacuum is done of stuff, purely no longer established remember. 3) the present idea of area is 4 dimensional. typical relativity has been shown to a huge degree, as you element out. typical Relativity combines area and time into spacetime. wondering about area and time is incorrect. Its like me declaring that the route "perfect" is qualitatively distinct from the route "left". reckoning on my coordinates and orientation and yours, my left might want to correctly be on your perfect. Similarily in GR, if I say activities got here about interior perfect right here sequence: A brought about B, you could properly be completely impressive as declaring precisely the option: on your reference body B got here about previously and brought about A. i assume this confuses you. i assume it confuses you because you have not studied the maths of typical Relativity. placed some months into it (thats assuming that you've already got a heritage in calculus, vector mechanics and linear algebra and it assumes you're way smarter than i'm - otherwise it would want to take some years to carry close). reliable luck and save publishing in peer reviewed journals.

Answer 7

There is space between earth and other planets or stars with zero gravity, you don't need a "gravitational shield" there.

Answer 8

Doubtful.



At least, no such technology yet exists on THIS planet.



Heck - we really don't fully understand gravity. Warping of the space-time continuum... what does THAT mean?