## Volume of a Negitive Sphere.

If I wanted to run a formula for the Volume of a Negitive Sphere on a computer which way would I write it?: V=(4pi/3)-r^3 or V=(4pi/3)r^(-3) or ? Has anyone else tried to run this formula on a computer?

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 What in the world is a negative sphere? If you have the formula for a negative sphere, just make a function to do the calculation. What is the problem?
 The problem is lack of math education. The question is do I put the negitive sign in front of the r or the 3? A negative sphere can be pictured as a reverse Big Bang. Also, I am wondering what happens if this equation is run on a computer. Tks 4 your replies.

## Volume of a Negitive Sphere.

So I'm guessing a negative sphere is a sphere with negative volume!? If it is, put the negative sign in front of the r. I'm not sure what you mean by "running" the equation on a computer. You can do this on a calculator if you wanted to, so...

 Recognitions: Gold Member Science Advisor Staff Emeritus 1) There is no such thing as a negative sphere. Radii can only be zero or positive. 2) A sphere is not a model of the big bang. It's just a sphere. 3) You don't "run an equation" on a computer. You can solve an equation with a computer, or you can use a computer to plug numbers into any formula you can dream up. That doesn't mean the results mean anything. - Warren
 Thank you for those replies. Another question if you pls. When one puts two mirrors in front of another, there seams to be an over lapping reflection, maybe into infinity. If at the moment of alining the two mirrors, the reflections take time to reflect back and forth into infinity, what would be a formula to describe this? Please be patient with my process, this is the first time I have asked any questions about my thoughts. Thks.
 Recognitions: Gold Member Science Advisor Staff Emeritus How about an object with constant negative curvature? Is it a closed figure? Does it have a finite volume?
 Maybe what you mean is an inverse sphere instead of a negative sphere?
 Yes Entropy that sounds like a better discription. Tks.
 Recognitions: Gold Member Science Advisor Staff Emeritus I can't say I know what an inverse sphere is, either. - Warren
 Lets say if you take the Singularity at the beginning of the Big Bang theory, and instead of it exploding outwards into some unknown medium, it instead exploded in upon itself. What would that equation be?
 Recognitions: Gold Member Science Advisor Staff Emeritus There's no "equation" for such a situation. - Warren
 Tks Warren for your replies. I see I am going to have a hard time equating my thoughts on reverse expansion from a "Zero Point". The only time this can happen, is at the very beginning of our Universe. I can see it , but I can not express it. I feel the equation "(4pi/3)-r^3" would cover this, if a number generator starting at Zero is introduced to "r". This number generator can run into infinity, or have a stopping point. I have seen on tv animation where it looks as if you are falling forever into a smaller point (like a black Hole), or like my mirror example from before. This is the way I see it.
 I fear for you PoPpAScience, because you say you suffer from lack of math education (well, we all do ) and you are trying to tackle problems that are so difficult. Big Bang theory requires a fairly advanced knowledge in math and physics.

 Quote by PoPpAScience When one puts two mirrors in front of another, there seams to be an over lapping reflection, maybe into infinity. If at the moment of alining the two mirrors, the reflections take time to reflect back and forth into infinity, what would be a formula to describe this?
Unfortunately, the light will not reflect back and forth forever as each reflection absorbs an amount of light. I remember being in an entranceway of an office building that had mirrors on all walls. As I looked at my reflections in one mirror, they repeated for what seemed like at least one hundred reflections, but eventually they faded away into darkness.

-Ray.

 Quote by rgoudie each reflection absorbs an amount of light
Even with pefectly reflecting mirrors, that would not work, because you need an integer number of photons with definite energy (color), as opposed to classical waves whose energy can be arbitrarily small.

But there are indeed a classical formulae to describe the wave model of light reflecting on ideal mirrors.

Recognitions:
Homework Help
When you say "(4pi/3)-r^3" do you mean $(4\pi/3)(-r^3)$ or $4\pi/3 - r^3$? The first one doesn't make any sense as all 3D geometrical objects have a positive volume and radius is also always positive. The 2nd one seem to be applicable for a situation where you have a hollow sphere with radius one r represents the radius of the space inside the sphere.