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no reference container, light refraction out
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Let there be a hollow container made of glass or some other transparent material, roughly the size and shape of an apple. Let the walls be of sufficient thickness for the container to be safely evacuated to some reasonable degree, perhaps around $10^{-8}$ mbar, and then hermetically and evenly sealed.

  1. How could one prove that the container is evacuated, and with what accuracy? Would x-ray crystallography, laser scattering, light absorption or emission or ultrasound be possible ways?

  2. Is there a simple way of demonstrating that the container is evacuated, perhaps by placing something inside it before sealing which behaves in a very specific and obvious way in a vacuum, without actually removing said vacuum? Aside from the obvious feather, which would fall without air resistance. I was thinking of something along the lines of a small quantity of cesium, but that wouldn't be distinguishable from an inert gas atmosphere.

Thanks!

Edit: There is no reference container to compare with and the container itself isn't standardized, so density/weight considerations are out, if I am right. Actually, so is light refraction, probably, as the container walls aren't really level enough, considering the small refraction delta mentioned in Andrew S.'s reply.

Let there be a hollow container made of glass or some other transparent material, roughly the size and shape of an apple. Let the walls be of sufficient thickness for the container to be safely evacuated to some reasonable degree, perhaps around $10^{-8}$ mbar, and then hermetically and evenly sealed.

  1. How could one prove that the container is evacuated, and with what accuracy? Would x-ray crystallography, laser scattering, light absorption or emission or ultrasound be possible ways?

  2. Is there a simple way of demonstrating that the container is evacuated, perhaps by placing something inside it before sealing which behaves in a very specific and obvious way in a vacuum, without actually removing said vacuum? Aside from the obvious feather, which would fall without air resistance. I was thinking of something along the lines of a small quantity of cesium, but that wouldn't be distinguishable from an inert gas atmosphere.

Thanks!

Let there be a hollow container made of glass or some other transparent material, roughly the size and shape of an apple. Let the walls be of sufficient thickness for the container to be safely evacuated to some reasonable degree, perhaps around $10^{-8}$ mbar, and then hermetically and evenly sealed.

  1. How could one prove that the container is evacuated, and with what accuracy? Would x-ray crystallography, laser scattering, light absorption or emission or ultrasound be possible ways?

  2. Is there a simple way of demonstrating that the container is evacuated, perhaps by placing something inside it before sealing which behaves in a very specific and obvious way in a vacuum, without actually removing said vacuum? Aside from the obvious feather, which would fall without air resistance. I was thinking of something along the lines of a small quantity of cesium, but that wouldn't be distinguishable from an inert gas atmosphere.

Thanks!

Edit: There is no reference container to compare with and the container itself isn't standardized, so density/weight considerations are out, if I am right. Actually, so is light refraction, probably, as the container walls aren't really level enough, considering the small refraction delta mentioned in Andrew S.'s reply.

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Zubo
Zubo
  • 330
  • 2
  • 10

Proving and demonstrating vacuum in container without breaking it

Let there be a hollow container made of glass or some other transparent material, roughly the size and shape of an apple. Let the walls be of sufficient thickness for the container to be safely evacuated to some reasonable degree, perhaps around $10^{-8}$ mbar, and then hermetically and evenly sealed.

  1. How could one prove that the container is evacuated, and with what accuracy? Would x-ray crystallography, laser scattering, light absorption or emission or ultrasound be possible ways?

  2. Is there a simple way of demonstrating that the container is evacuated, perhaps by placing something inside it before sealing which behaves in a very specific and obvious way in a vacuum, without actually removing said vacuum? Aside from the obvious feather, which would fall without air resistance. I was thinking of something along the lines of a small quantity of cesium, but that wouldn't be distinguishable from an inert gas atmosphere.

Thanks!