- #351
Nigel
- 170
- 0
Originally posted by Brad_Ad23
Also, to Nigel.
Alright, you are treating spacetime (or just space) as a fluid here. How is it the sun or any other body can shield an object from pressure? If I put two balls in a tank under water, they both experience equal pressure. So, even if the sun somehow shielded the Earth from pressure, there is a lot of distance between the two, and plenty of space pressure from outside the line of sight of the two bodies to flow inbetween. Even then, in the line of sight between the two objects, there will be less pressure, due to mutual shielding..so should not objects be drawn to exist between the two? (PS I know the answer to this--it even supports you, but I want to make sure you catch it).
At any rate, let us also examine Yogi's situation. We have the same amount of mass present, but it is in a much smaller area. How does this smaller area still exert the same gravitational pull on earth? Einstein's explination of spacetime curvature serve to explain this, and one can see that in Newtonian mechanics the object is treated as a point anyways, but your explination requires there to be some surface area to shield. I agree that in a lot of cases your idea can be viewed as equivalent, but there do appear to be some differences here in what your idea will predict. The cause of gravity in your model suggests that there should be less attraction then between the black hole sun and the earth. Were that so, other observational evidence of binary systems with a black hole present would be far off from what they are (which have their orbital mechanics worked out the Einstein way).
Since air and water are not continuums, but particle-composed, they seep around gaps fairly quickly. But if you are quick you can beat the particle velocity and use them to model a continuum.
For instance, in the air the air pressure, 101 kiloPascals or 14.7 pounds per square inch, would be enough to make objects "attract" each other, if the air did not seep between them. When you have a smooth surface and you put a piece of rubber against it (called a "suction plunger" in England), then yoy find that its apparent weight is more than its actual weight by an amount equal to the 14.7 pounds per square inch air pressure. Hence the suction plunger attracts the surface because it is being pushed down by air pressure.
The weight due to gravity is likewise caused by the space pressure.
Now for black holes, their mass is calculated, and the evidence is not that precise. In addition, many assumptions are made about gravity in order to get the mass calculations done. Most of these estimates are uncertain by a very large factor, although I hope that decent results will arive soon which can test this properly.