Could General Relativity be wrong?

[Hypercube]

I was reading a book about General Relativity the other day, and something occured to me; there may be a serious flaw in Einstein's reasonings. What jumped out at me is that although the common analogy of a bowling ball making a dent in a trampoline is a convienient way of grasping the concept of General Relativity, the flaw lyes in the fact that that analogy deals with a 3D ball (the sun) and a 2D surface (spacetime?) but this view is not applicable in the real world because spacetime is not two dimensional, it is three dimensional. This obviously means that there is a flaw in the common understanding of General Relativity, because that would mean that a 3D object would be sitting on a 3D surface, and this is a mathematical and physical impossibility. The only way for an object to "sit" on a surface is for that surface to be one less dimension that the object. So how can General Relativity be correct?

[iNow]

It's held up against experiment pretty well. Wouldn't it be more accurate to call it "incomplete" or suggest that it doesn't apply on all scales, instead of making a blanket comment that "it's wrong?"

[Hypercube]

You're right, I shouldn't have said that is was wrong, just incomplete, as you say.

[Cap'n Refsmmat]

I was reading a book about General Relativity the other day, and something occured to me; there may be a serious flaw in Einstein's reasonings. What jumped out at me is that although the common analogy of a bowling ball making a dent in a trampoline is a convienient way of grasping the concept of General Relativity, the flaw lyes in the fact that that analogy deals with a 3D ball (the sun) and a 2D surface (spacetime?) but this view is not applicable in the real world because spacetime is not two dimensional, it is three dimensional. This obviously means that there is a flaw in the common understanding of General Relativity, because that would mean that a 3D object would be sitting on a 3D surface, and this is a mathematical and physical impossibility. The only way for an object to "sit" on a surface is for that surface to be one less dimension that the object. So how can General Relativity be correct?

 

That's only an analogy to help explain the theory. Einstein never said that was the actual mechanism by which it worked.

[Klaynos]

That's only an analogy to help explain the theory. Einstein never said that was the actual mechanism by which it worked.

 

True. You're reading too far into the analogy...

 

But we do know that GR is incomplete, as it goes to a singularity in black holes.

[Graviphoton]

I'll repeat what was said, with an addition.

 

Yeh, its only an analogy. The fabric which the ball is supposed to be sitting on, in fact makes up the dimensional qualities of the ball itself.

 

So, the 3D sun, is 3D, because the fabric it exists in is also 3D, added one time dimension.

[Sayonara]

I don't know why people even bother with the fabric or rubber sheet analogy. Envisioning it in a volumetric mode is hardly difficult.

[Hypercube]

That may be true, but it still can't be denied that the common analogy is misunderstood at best, since as I said, a 3D object cannot "sit" on a 3D surface, or a 4D surface for that matter. Shouldn't that mean that a stars gravity would warp all the space around it evenly in a kind of sphere?

[swansont]

The rubber sheet analogy is an amalgam; it shows a 2-D representation of the geometry, and an image of the celestial body is superimposed on it as a reference.

[Obelix]

I was reading a book about General Relativity the other day, and something occured to me; there may be a serious flaw in Einstein's reasonings. What jumped out at me is that although the common analogy of a bowling ball making a dent in a trampoline is a convienient way of grasping the concept of General Relativity, the flaw lyes in the fact that that analogy deals with a 3D ball (the sun) and a 2D surface (spacetime?) but this view is not applicable in the real world because spacetime is not two dimensional, it is three dimensional. This obviously means that there is a flaw in the common understanding of General Relativity, because that would mean that a 3D object would be sitting on a 3D surface, and this is a mathematical and physical impossibility. The only way for an object to "sit" on a surface is for that surface to be one less dimension that the object. So how can General Relativity be correct?

 

Even as far as the analogy is concerned, 3D sun sits on 4D SPACETIME, not 3D space alone. Time is also curved.

 

Appart from the analogy, Sun, Earth, or any mass, is not something independent of spacetime, seperate from it. The analogy with the rubber sheet is misleading. A massive object is not something "sitting on space or spacetime, causing it to curve": According to Einstein's gravitational field equations, it is spacetime itself, or, more specifically, a geometric feature of the latter. It is a curved neighbourhood of spacetime, a specific local geometry thereof.

 

It is not General Relativity that is incomplete; it is the rubber sheet analogy that is oversimplified.

 

True. You're reading too far into the analogy...

 

But we do know that GR is incomplete, as it goes to a singularity in black holes.

 

I see nothing "incomplete" in the concept of a singularity, whether in a black hole or at the "beginning" of spacetime (nor do I see any "beginning" of spacetime for that matter).

 

Singularities may or may not exist - till either is proved beyond doubt by solid observational facts - yet, as a theoretical concept, they are terribly misunderstood. I think they must not be viewed as something existing statically, with an "eventually achieved" infinite density, or as an area where time "has eventually come to a halt", but rather as some kind of "lower limit" ("infimum") to which spactime, matter, energy, along with their properties, converge dynamically, but never reach conclusively. That is, something like classical infinity of Newtonian Universe: Such an infinity didn't exist anywhere "as such". It was just an abstract global outcome of all endless dynamical processes in the Universe. There is nothing more or less metaphysical in Newtonian infinity compaired to singularities.

 

A good analogy is that with the "absolute zero", as suggested by Malocolm Ludvigsen in his "General Relativity", Cambridge University Press.

[Klaynos]

Singularities are not physical. Ask any physicist and they'll tell you they indicate a problem with the theory.

[pioneer]

If we use the analogy of a bowling ball on a rubber sheet, does this imply space-time is expanding since it creates stretching? Before the bowling ball is placed, we have say 9 square meters of rubber membrane. The bowling ball will stretch the rubber membrane so the final surface area is greater than 9 square meters. Einstein would have noticed this, so I assumed this is what he meant. If he meant the opposite, or space-time contraction, shrink plastic or a wet wool blanket and heat gun would have been used.

 

To test whether space-time expands, instead of time dilation we should get time expansion where time speeds up at the bottom of the well, relative to the time scale on the bulk rubber fabric of space-time. If we look at stars, the events in the center occur using fastest average time scale. In fact, only the fastest events are possible in the center of a star. This is the bottom of the bowling ball well. One will not find atomic transitions in the core of a star, because the time scale is so stretched only the fastest events can be in that reference.

 

This actually explains a black hole better. Just to use numbers, one cubit meter of space is stretched to thousands of cubic meters. From our reference we still see the 1 cubic meter, but if you fall into it we will need to travel the thousands of meters. One way to look at this affect is to think in terms of a microscope. One little drop of pond water under the microscope allows us to enter an expanded reference where thing are small and where small distances now appear expanded. At the same time, light coming from the drop through the microscope to our eye is this reference, widens. This is the analogy for the red shift.

[Obelix]

Singularities are not physical. Ask any physicist and they'll tell you they indicate a problem with the theory.

 

There are several attempts to interprete singularities in such a way as to include them in a physical scheme. I suggest yet one more.

[bascule]

analogy deals with a 3D ball (the sun) and a 2D surface (spacetime?) but this view is not applicable in the real world because spacetime is not two dimensional, it is three dimensional.

 

Take the 2D rubber sheet and rotate it 360° along all three axes of 3D space, and you'll get a better idea of what the theory is describing.

 

That said, General Relativity is known to be wrong to certain extents. Satellite telemetry data has shown certain aberrations from the values GR predicts under certain circumstances, and more and more instances of this are popping up. In addition to the other problems explained above, these satellites show that there's something to their behavior which GR does not account for.

 

That said, the theory has been confirmed by innumerable experiments and for most circumstances it seems to hold up just fine.

[lakmilis]

If we use the analogy of a bowling ball on a rubber sheet, does this imply space-time is expanding since it creates stretching? Before the bowling ball is placed, we have say 9 square meters of rubber membrane. The bowling ball will stretch the rubber membrane so the final surface area is greater than 9 square meters. Einstein would have noticed this, so I assumed this is what he meant. If he meant the opposite, or space-time contraction, shrink plastic or a wet wool blanket and heat gun would have been used.

 

Of course he did... he used the Minkowski metric for this

[pioneer]

What I was trying to do was correlate what is happening to space-time with observational data. Time dilation doesn't make any sense in the center of gravity of stars. The practical situation that would arise is time slowing down at the bottom of the well. In the center of gravity nuclear reactions would appear to slow relative to what should be predicted in labs here on earth. This would cause the largest stars to time dilate the most at center, making them burn slower than predicted. The stella profile would have a slow time dilated core with the surface activity appearing to get faster.

 

With time and distance expansion, sort of a microscope affect, this allows for movement toward singularities. Let me give an analogy. We start with a rock, which looks solid enough. As we magnify or expand distance we notice there is plenty of space where the electron clouds are. The only solid obstructions appear to be the nuclei. This give us more room to pack tighter, with gravity, all the way to neutron density. We zoom in further with the microscope or expand distance even more, we notice there is now space. With time also speeding up the only particles that can exist need to be able to move within this very fast time reference. This places a limit on particles with only those that fit the reference able to fill the space.

 

If we take it to the limit of a point, then the only particles that can exist can only last for an instant of time or undergo instantaneous transitions. This eliminates all particles we know of. These point-instants can overlap at a point. They can overlap because at any instant there is only one of them. But over time they all can take a turn. To us we see a constant looking point since we can't measure an instant anymore than a point.

[rwjefferson]

... What jumped out at me is that although the common analogy of a bowling ball making a dent in a trampoline is a convienient way of grasping the concept of General Relativity, the flaw lyes in the fact that that analogy deals with a 3D ball (the sun) and a 2D surface (spacetime?)...

 

It is not so much that General Relativity is wrong; it is that 'equivalence' has become dogma.

 

It is no more the curve of space that causes planets to accelerate toward a star, than it is the curve of the trampoline that causes balls to accelerate toward a heavier ball. Acceleration is by gravity; not by the equivalent graph. Gravity curves spacetime as low pressure curves atmosphere. Yet it is not the curve that forces the vortex.

 

When Einstein differentiated spacetime acceleration to constant time, information was lost . Einstein demonstrated the wave (curve) of time but lost sight of the particles of space.

 

Curve is not a force; curve is a relative reaction to force.

 

An astronaut that experiences force as acceleration of one G experiences change of space by time by thirty two feet per second per second; even while sitting on earth.

 

Mass accelerates spacetime by gravity, just as mass accelerates mass by inertia. Curve is not acceleration; curve is relative reaction to acceleration.

 

Peace

rwj

 

dogma is entrenched belief that resists just consideration of simple truth