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Is space really a vacuum?

  1. Oct 10, 2011 #1
    Think about it. If space was a vacuum how would energy from the sun (which has a mass equivalency) be radiated. Supposedly devoid of matter this is still energy which makes matter and almost every day we see the sun as something in our physical realm. Are there experiments detailing what happens in transformation from an atmosphere to a vacuum?
     
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  3. Oct 10, 2011 #2

    russ_watters

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    Welcome to PF!

    By definition, radiated energy does not require an atmosphere and in fact transfers best in a vacuum. An atmosphere transfers heat via convection.

    I'm not sure what type of experiments you are looking for....do orbiting spacecraft, not subject to any substantial amount atmospheric drag, qualify?
     
  4. Oct 10, 2011 #3
    This was quite a debate around the late 1800s. See here:

    http://en.wikipedia.org/wiki/Luminiferous_aether

    This was the experiment that showed there was no medium that electromagnetic radiation was traveling through:
    http://en.wikipedia.org/wiki/Michelson-Morley_experiment

    As for the transition from atmosphere to vacuum, the problem is there is no hard line. Rather, the atmosphere thins out more and more and eventually there are only single atoms per cubic meter. If you want proof that the atmosphere actually thins out the way we expect it to, you can look at various spacecraft we have launched outside of Earth's orbit.
     
  5. Oct 11, 2011 #4
    Is space really a vacuum? Not really. Throughout the cosmos are scattered atoms , molecules, subatomic particles scattered everywhere and moving rapdily and randomly.
    Far enough out from the earth's atmosphere, it is difficult to detect any of this though.
     
  6. Oct 11, 2011 #5
    "Vacuum" has come to mean a volume devoid of permanent mass, not a volume devoid of everything. Thus outer space is well described as a vacuum (neglecting the small amount of dust), but that does not mean it is completely empty. Outer space contains photons from all the stars, the cosmic background radiation, dust, etc. Even if you built a box that blocked out all the radiation and you sucked out all the matter, you would still not have a volume that is completely empty because of http://en.wikipedia.org/wiki/Vacuum_energy" [Broken], which are particles that fluctuate into existence out nothing.
     
    Last edited by a moderator: May 5, 2017
  7. Oct 15, 2011 #6
    I used to work in the vacuum business, and most of our references to the space around the earth and moon was as a "dirty vacuum." There is no such thing as a perfect vacuum. Try as you might, there's always material leaking into your chamber. The art of creating an ultra high vacuum was just that - an art. But, we could easily get much better vacuums in the lab than what was to be had in near space.
     
  8. Oct 16, 2011 #7

    DaveC426913

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    There seems to be a couple of confused thoughts here.

    While it is true energy can be formed into matter, that does not mean that energy always results in matter. The space between sun and Earth is filled with energy, but it is not matter.

    Vacuum is still vacuum, even when permeated with energy.

    This is ambiguous. Transformation of what?
     
  9. Oct 16, 2011 #8
    Most physicists subscribe to a 'duality' theory of light. It's supposed to be based on both particles (e.g. photons) and 'wave-like' (meaning that it would require a solid-based medium (such as the 'ether'). In either case, it suggests that space must be full of something - else how can light emanate from all sources in all directions?
     
  10. Oct 16, 2011 #9

    DaveC426913

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    Yes, photons are described as particles. But they have no mass and are not classified as matter.
     
  11. Oct 16, 2011 #10

    russ_watters

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    Nor is it true that an ether is required for wavelike properties.
     
  12. Oct 16, 2011 #11
    The transformation of the atmosphere's qualities into spaces qualities as you approach space.
     
  13. Oct 16, 2011 #12
    Space is full of something. It is full of fields. An electromagnetic wave (commonly known as light) is a wave in the electromagnetic field. However, a vacuum is not full of matter (unless you include vacuum energy, but that is a completely different story, based on the uncertainty principle rather than light.) Eather models don't work because eather has to be completely unmeasurable, while at the same time extremely dense to account for the extremely fast speed of light.
     
  14. Oct 16, 2011 #13

    DaveC426913

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    Sorry. Maybe I'm obtuse. Still doesn't make sense.

    How does the quality of one thing transform into the quality of something else?

    Is that like the fuzzy quality of grass "transforms" into the hard quality of pavement?

    OK, so what qualities did you want to examine? Pressure? Molecules per unit volume?
     
  15. Oct 17, 2011 #14
    While the OP may seem to be confused with a vacuum containing photons, and everybody is doing a good job of clearing this up, I would like to point out for exactness that the sun emits more than photons. The sun also ejects the solar wind which is comprised of particles with mass; electrons, protons, alpha particles. So the space between earth and sun is not a perfect vacuum, buts its because of the solar wind and interplanetary dust and not because of the photons.
     
  16. Oct 18, 2011 #15
    "Space" is quite a vague term though. I assumed he meant intergalactic space.
     
  17. Oct 18, 2011 #16

    DaveC426913

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    Why would you assume that? The OP explicitly mentions Earth's atmo and radiation from the sun.
     
  18. Oct 18, 2011 #17
    Yes, but the question implied the space is empty space, with the exception of the eather, which seems to me to have similar properties to intergalactic space. I read it as another star or galaxy, instead of the sun.
     
  19. Oct 18, 2011 #18
    This seems like a backwards assumption: In fact, particles (matter) in the earth's atmosphere protect us from the heat and radiation from the sun...especially high energy radiation that would possibly cause enough cancer to just about destroy most life here.

    As noted already, energy from the sun is radiated (via electromagnetic waves) very
    efficiently through the partial vacuum that is "outer space".
     
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