3 ms·

So, is that a strike against string theory's extra dimensions, or is it another type of extra dimension being ruled out?

whatshisface 8y ago
It is a strike against the idea that over long distances, the spherical shell of "expanding and thinning" gravity can go down faster than 1/r^2 (which would come about from A=pi*r^2, the area of a sphere in three dimensions), achieving that goal by slipping in to dimensions higher than three. However now we have found that gravitational waves are about as strong as we expect it looks like gravity isn't leaving the world of 3+1D.
- skh 8y ago
  Sphere's have surface area and volume. Neither of those quantities is given by the formula for the area of a circle. I’m not a physicist and can’t speak to the merits of the rest of your post but this error of yours makes me doubt your post's veracity. Did you make a mistake in your parenthetical remark? Maybe it edit if you have.
  - dfmooreqqq 8y ago
    I assumed it was a reference to the surface area of a sphere - which is 4pir^2. The point would still hold.
    - skh 8y ago
      Makes sense. That’s what I would have thought if not for the area of a sphere in three dimensions remark.
      - empath75 8y ago
        Area = surface area not volume. Physicists tend to drop constant factors when they do calculations, I’ve noticed.
        skh 8y ago
        A sphere has surface area and volume. I didn’t claim or imply that I thought area meant volume. It does not have area and the formula for the surface area of a sphere is not pi r^2. I mentioned this in my original post. Then there is the remark that whatshisface made: A = pi r^2, the area of a sphere in three dimensions. That is wrong and most likely a mistake. When talking about dropping a constant factor are you referring to the 1/r^2 part or dropping a 4 in the statement A=pi r^2. Because if the latter then why keep pi? That’s a constant.
        whatshisface 8y ago
        The constants perfectly divide out in this case, adding the pi was an afterthought so that people would recognize it as an area. Yes... It should have had a 4 as well. Too late to edit now.
- Razengan 8y ago
  [Complete layman here.] Could it also not mean that gravity is "just" a 3D (or 3+1D) phenomenon? For example, what does gravity mean in 2D? Can we rule out that our 3D† universe is not a rarity in a larger, 4D universe, much like how true-2D planes are a rarity in our 3D universe? † D as in spatial dimension, excluding time.
  - whatshisface 8y ago
    If there are extra dimensions that gravity doesn't exit into, this experiment won't detect them. It is not curtians for string theory.

whatshisface 8y ago

It is a strike against the idea that over long distances, the spherical shell of "expanding and thinning" gravity can go down faster than 1/r^2 (which would come about from A=pi*r^2, the area of a sphere in three dimensions), achieving that goal by slipping in to dimensions higher than three. However now we have found that gravitational waves are about as strong as we expect it looks like gravity isn't leaving the world of 3+1D.

skh 8y ago
Sphere's have surface area and volume. Neither of those quantities is given by the formula for the area of a circle. I’m not a physicist and can’t speak to the merits of the rest of your post but this error of yours makes me doubt your post's veracity. Did you make a mistake in your parenthetical remark? Maybe it edit if you have.
- dfmooreqqq 8y ago
  I assumed it was a reference to the surface area of a sphere - which is 4pir^2. The point would still hold.
  - skh 8y ago
    Makes sense. That’s what I would have thought if not for the area of a sphere in three dimensions remark.
    - empath75 8y ago
      Area = surface area not volume. Physicists tend to drop constant factors when they do calculations, I’ve noticed.
      - skh 8y ago
        A sphere has surface area and volume. I didn’t claim or imply that I thought area meant volume. It does not have area and the formula for the surface area of a sphere is not pi r^2. I mentioned this in my original post. Then there is the remark that whatshisface made: A = pi r^2, the area of a sphere in three dimensions. That is wrong and most likely a mistake. When talking about dropping a constant factor are you referring to the 1/r^2 part or dropping a 4 in the statement A=pi r^2. Because if the latter then why keep pi? That’s a constant.
        whatshisface 8y ago
        The constants perfectly divide out in this case, adding the pi was an afterthought so that people would recognize it as an area. Yes... It should have had a 4 as well. Too late to edit now.
Razengan 8y ago
[Complete layman here.] Could it also not mean that gravity is "just" a 3D (or 3+1D) phenomenon? For example, what does gravity mean in 2D? Can we rule out that our 3D† universe is not a rarity in a larger, 4D universe, much like how true-2D planes are a rarity in our 3D universe? † D as in spatial dimension, excluding time.
- whatshisface 8y ago
  If there are extra dimensions that gravity doesn't exit into, this experiment won't detect them. It is not curtians for string theory.