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Vacuum of Space Question


What exactly does outer space contain?What does it mean to say 'space exists?'Question about extreme space distortion and creation of a new dimensionHow do we know that there is no border at the end of “infinite” space?High quality Space-related blog/website?Could vacuum energy dim standard candles?Mass of quantum fluctuations in space?Does space not make sound, or can we just not hear it?Is it relevant to ask the limits of space?Who was the first to realize that the Earth is surrounded by vacuum?













2












$begingroup$


The vacuum of space is incredibly powerful
1 X 10 ^-17 torr



I’m editing my question to reflect the vacuum between the earth and the moon 1 X 10 ^-11 torr



How can such a vacuum in close proximity to the earth coexist with the open system of earth’s atmosphere whereby debris from space can enter in?



Apparently according to uhoh the vacuum of space has a gradient. I wonder how that proports to the second law of thermodynamics.




  • https://www.raclub.org/Documents/Programs/VACUUM.pdf


  • https://web.pa.msu.edu/courses/2014fall/PHY451/Lectures/Vacuum.pdf











share|improve this question









New contributor




Autodidact is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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$endgroup$

















    2












    $begingroup$


    The vacuum of space is incredibly powerful
    1 X 10 ^-17 torr



    I’m editing my question to reflect the vacuum between the earth and the moon 1 X 10 ^-11 torr



    How can such a vacuum in close proximity to the earth coexist with the open system of earth’s atmosphere whereby debris from space can enter in?



    Apparently according to uhoh the vacuum of space has a gradient. I wonder how that proports to the second law of thermodynamics.




    • https://www.raclub.org/Documents/Programs/VACUUM.pdf


    • https://web.pa.msu.edu/courses/2014fall/PHY451/Lectures/Vacuum.pdf











    share|improve this question









    New contributor




    Autodidact is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.







    $endgroup$















      2












      2








      2





      $begingroup$


      The vacuum of space is incredibly powerful
      1 X 10 ^-17 torr



      I’m editing my question to reflect the vacuum between the earth and the moon 1 X 10 ^-11 torr



      How can such a vacuum in close proximity to the earth coexist with the open system of earth’s atmosphere whereby debris from space can enter in?



      Apparently according to uhoh the vacuum of space has a gradient. I wonder how that proports to the second law of thermodynamics.




      • https://www.raclub.org/Documents/Programs/VACUUM.pdf


      • https://web.pa.msu.edu/courses/2014fall/PHY451/Lectures/Vacuum.pdf











      share|improve this question









      New contributor




      Autodidact is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.







      $endgroup$




      The vacuum of space is incredibly powerful
      1 X 10 ^-17 torr



      I’m editing my question to reflect the vacuum between the earth and the moon 1 X 10 ^-11 torr



      How can such a vacuum in close proximity to the earth coexist with the open system of earth’s atmosphere whereby debris from space can enter in?



      Apparently according to uhoh the vacuum of space has a gradient. I wonder how that proports to the second law of thermodynamics.




      • https://www.raclub.org/Documents/Programs/VACUUM.pdf


      • https://web.pa.msu.edu/courses/2014fall/PHY451/Lectures/Vacuum.pdf








      cosmology atmosphere space vacuum






      share|improve this question









      New contributor




      Autodidact is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.











      share|improve this question









      New contributor




      Autodidact is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.









      share|improve this question




      share|improve this question








      edited 18 mins ago









      uhoh

      6,02221761




      6,02221761






      New contributor




      Autodidact is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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      asked 2 hours ago









      AutodidactAutodidact

      1114




      1114




      New contributor




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      Check out our Code of Conduct.





      New contributor





      Autodidact is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.






      Autodidact is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.






















          1 Answer
          1






          active

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          3












          $begingroup$

          update: This answer was written before the question was modified. I've tried to explain where a value like 10-17 Torr for deep space might come from, but it's since been dropped in lieu of 10^-11 Torr at the Moon, which is probably a better way to formulate the question.



          I think the answer is the same, two points very far away can have very different pressures. They can coexist in the same solar system, just not right next to each other. I think "Why doesn't the Moon have at least a small atmosphere?" could also be an excellent, but very different question.





          In a comment the OP links to the presentation VACUUM (There’s nothing to it… ) written from the perspective of an engineer in the semiconductor manufacturing industry.



          Slide 6 gives examples of vacuum levels in different situations:



          Going down:




          • Low vacuum: 760 Torr to 1 x 10-3 Torr


            • Vacuum cleaner: to 600 Torr

            • Thermos bottle 10-3 Torr



          • High vacuum: 10-3 to 10-9 Torr


            • Electron microscope

            • Ion Implanter
              – Evaporator
              – Sputterer



          • Ultra high vacuum: 10-9 to 10-12 Torr


            • CERN LHC: 1 x 10-10 Torr

            • Moon’s surface: 1 x 10-11 Torr

            • Deep Space 1 x 10-17 Torr = 0.000,000,000,000,000,01 Torr




          So we can see that the value of 1 x 10-17 Torr is associated with a place in "Deep Space" which is (probably) beyond that of the Moon.



          Let's see if we can figure out where the author is getting that number.



          According to the Wikipedia article on the interstellar medium (space between stars, far away from solar systems and other things):




          In all phases, the interstellar medium is extremely tenuous by terrestrial standards. In cool, dense regions of the ISM, matter is primarily in molecular form, and reaches number densities of 106 molecules per cm3 (1 million molecules per cm3). In hot, diffuse regions of the ISM, matter is primarily ionized, and the density may be as low as 10−4 ions per cm3. Compare this with a number density of roughly 1019 molecules per cm3 for air at sea level, and 1010 molecules per cm3 (10 billion molecules per cm3) for a laboratory high-vacuum chamber.




          It is harder to talk about pressure than density because pressure is related to both number density and temperature. The atmosphere is more than 10x hotter than interstellar medium, so let's look for a number density ratio of 1/10 of 1000 Torr versus 10^-17 torr, or a ratio of 10^19.



          If (according to Wikipedia) Earth's atmosphere has a density of 10^19 per cm^3, we're looking for a density of 1 per cm^3. Checking Wikipedia we can see that there are components of the interstellar medium with number densities between 10^6 and 10^-4.



          It looks like the value in the presentation a rough ballpark estimate, but isn't off by more than a handful of orders of magnitude ;-)




          How can such a vacuum coexist with the open system of earth’s atmosphere whereby debris from space can enter in?




          While these two pressures can coexist in the same universe, they don't coexist in proximity at all. The interstellar medium is very, very far away from Earth's atmosphere, on the order of a lightyear.



          Gravity keeps Earth's atmosphere nearby Earth, the solar system has gas produced by (and attracted by) the Sun's gravity. In interstellar space, there just isn't any source of gas, and what might have been there at one time has moved away, towards sources of gravity, over billions of years.






          share|improve this answer











          $endgroup$













          • $begingroup$
            Thank you for your response. Are you disputing the pressure on the moon also? Because if the pressure is out by a handful of magnitudes certainly between the moon and earth’s atmosphere there exist a vacuum of some sort at least as weak as a dyson vacuum cleaner. The notion that gravity holds the atmosphere in place but still is weak enough to allow gases to stratify depending on density or pressure is very difficult to wrap my head around. Not to mention that pressure requires something to press onto. What is the atmosphere pressing onto? The vacuum?
            $endgroup$
            – Autodidact
            1 hour ago












          • $begingroup$
            @Autodidact I have not disputed anything. I'm in general agreement with the powerpoint; within several orders of magnitude at least. The word "coexist" makes your question difficult to answer because you don't explain what you mean. They can coexist in the same universe, but not close to each other. I think a question about how the atmosphere ends up stratified in pressure due to gravity is a great one, but probably is better to ask in Earth Science SE or Physics SE.
            $endgroup$
            – uhoh
            1 hour ago






          • 1




            $begingroup$
            @Autodidact You may find several questions and answers like that in those sites already, best to read them before asking something that's been answered. Here is some related math, but there are probably better places to find a useful and head-wrappable explanation. en.wikipedia.org/wiki/Scale_height
            $endgroup$
            – uhoh
            1 hour ago








          • 1




            $begingroup$
            Thank you for the link. If this question is not asked in the correct stack, my sincerest apologies. Also my edit was not intended as a moving target, I didn’t want it dismissed. As for the atmosphere pressure, while the link provides a distance it doesn’t explain my inquiry, what is it pressing upon to generate the distance? That is a question to which I cannot seem to find an answer to. Gravity seems to be the answer but it’s powers are conflicting as I’ve pointed out. It’s sufficiently strong to resist a vacuum of 10^-11 but weak enough to let gas particles up 8.5 km up into the atmosphere.
            $endgroup$
            – Autodidact
            52 mins ago






          • 1




            $begingroup$
            The Moon kind of does have an atmosphere, but it's very thin, and its total mass is under 10 tonnes. See en.wikipedia.org/wiki/Atmosphere_of_the_Moon
            $endgroup$
            – PM 2Ring
            44 mins ago











          Your Answer





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          1 Answer
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          1 Answer
          1






          active

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          active

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          3












          $begingroup$

          update: This answer was written before the question was modified. I've tried to explain where a value like 10-17 Torr for deep space might come from, but it's since been dropped in lieu of 10^-11 Torr at the Moon, which is probably a better way to formulate the question.



          I think the answer is the same, two points very far away can have very different pressures. They can coexist in the same solar system, just not right next to each other. I think "Why doesn't the Moon have at least a small atmosphere?" could also be an excellent, but very different question.





          In a comment the OP links to the presentation VACUUM (There’s nothing to it… ) written from the perspective of an engineer in the semiconductor manufacturing industry.



          Slide 6 gives examples of vacuum levels in different situations:



          Going down:




          • Low vacuum: 760 Torr to 1 x 10-3 Torr


            • Vacuum cleaner: to 600 Torr

            • Thermos bottle 10-3 Torr



          • High vacuum: 10-3 to 10-9 Torr


            • Electron microscope

            • Ion Implanter
              – Evaporator
              – Sputterer



          • Ultra high vacuum: 10-9 to 10-12 Torr


            • CERN LHC: 1 x 10-10 Torr

            • Moon’s surface: 1 x 10-11 Torr

            • Deep Space 1 x 10-17 Torr = 0.000,000,000,000,000,01 Torr




          So we can see that the value of 1 x 10-17 Torr is associated with a place in "Deep Space" which is (probably) beyond that of the Moon.



          Let's see if we can figure out where the author is getting that number.



          According to the Wikipedia article on the interstellar medium (space between stars, far away from solar systems and other things):




          In all phases, the interstellar medium is extremely tenuous by terrestrial standards. In cool, dense regions of the ISM, matter is primarily in molecular form, and reaches number densities of 106 molecules per cm3 (1 million molecules per cm3). In hot, diffuse regions of the ISM, matter is primarily ionized, and the density may be as low as 10−4 ions per cm3. Compare this with a number density of roughly 1019 molecules per cm3 for air at sea level, and 1010 molecules per cm3 (10 billion molecules per cm3) for a laboratory high-vacuum chamber.




          It is harder to talk about pressure than density because pressure is related to both number density and temperature. The atmosphere is more than 10x hotter than interstellar medium, so let's look for a number density ratio of 1/10 of 1000 Torr versus 10^-17 torr, or a ratio of 10^19.



          If (according to Wikipedia) Earth's atmosphere has a density of 10^19 per cm^3, we're looking for a density of 1 per cm^3. Checking Wikipedia we can see that there are components of the interstellar medium with number densities between 10^6 and 10^-4.



          It looks like the value in the presentation a rough ballpark estimate, but isn't off by more than a handful of orders of magnitude ;-)




          How can such a vacuum coexist with the open system of earth’s atmosphere whereby debris from space can enter in?




          While these two pressures can coexist in the same universe, they don't coexist in proximity at all. The interstellar medium is very, very far away from Earth's atmosphere, on the order of a lightyear.



          Gravity keeps Earth's atmosphere nearby Earth, the solar system has gas produced by (and attracted by) the Sun's gravity. In interstellar space, there just isn't any source of gas, and what might have been there at one time has moved away, towards sources of gravity, over billions of years.






          share|improve this answer











          $endgroup$













          • $begingroup$
            Thank you for your response. Are you disputing the pressure on the moon also? Because if the pressure is out by a handful of magnitudes certainly between the moon and earth’s atmosphere there exist a vacuum of some sort at least as weak as a dyson vacuum cleaner. The notion that gravity holds the atmosphere in place but still is weak enough to allow gases to stratify depending on density or pressure is very difficult to wrap my head around. Not to mention that pressure requires something to press onto. What is the atmosphere pressing onto? The vacuum?
            $endgroup$
            – Autodidact
            1 hour ago












          • $begingroup$
            @Autodidact I have not disputed anything. I'm in general agreement with the powerpoint; within several orders of magnitude at least. The word "coexist" makes your question difficult to answer because you don't explain what you mean. They can coexist in the same universe, but not close to each other. I think a question about how the atmosphere ends up stratified in pressure due to gravity is a great one, but probably is better to ask in Earth Science SE or Physics SE.
            $endgroup$
            – uhoh
            1 hour ago






          • 1




            $begingroup$
            @Autodidact You may find several questions and answers like that in those sites already, best to read them before asking something that's been answered. Here is some related math, but there are probably better places to find a useful and head-wrappable explanation. en.wikipedia.org/wiki/Scale_height
            $endgroup$
            – uhoh
            1 hour ago








          • 1




            $begingroup$
            Thank you for the link. If this question is not asked in the correct stack, my sincerest apologies. Also my edit was not intended as a moving target, I didn’t want it dismissed. As for the atmosphere pressure, while the link provides a distance it doesn’t explain my inquiry, what is it pressing upon to generate the distance? That is a question to which I cannot seem to find an answer to. Gravity seems to be the answer but it’s powers are conflicting as I’ve pointed out. It’s sufficiently strong to resist a vacuum of 10^-11 but weak enough to let gas particles up 8.5 km up into the atmosphere.
            $endgroup$
            – Autodidact
            52 mins ago






          • 1




            $begingroup$
            The Moon kind of does have an atmosphere, but it's very thin, and its total mass is under 10 tonnes. See en.wikipedia.org/wiki/Atmosphere_of_the_Moon
            $endgroup$
            – PM 2Ring
            44 mins ago
















          3












          $begingroup$

          update: This answer was written before the question was modified. I've tried to explain where a value like 10-17 Torr for deep space might come from, but it's since been dropped in lieu of 10^-11 Torr at the Moon, which is probably a better way to formulate the question.



          I think the answer is the same, two points very far away can have very different pressures. They can coexist in the same solar system, just not right next to each other. I think "Why doesn't the Moon have at least a small atmosphere?" could also be an excellent, but very different question.





          In a comment the OP links to the presentation VACUUM (There’s nothing to it… ) written from the perspective of an engineer in the semiconductor manufacturing industry.



          Slide 6 gives examples of vacuum levels in different situations:



          Going down:




          • Low vacuum: 760 Torr to 1 x 10-3 Torr


            • Vacuum cleaner: to 600 Torr

            • Thermos bottle 10-3 Torr



          • High vacuum: 10-3 to 10-9 Torr


            • Electron microscope

            • Ion Implanter
              – Evaporator
              – Sputterer



          • Ultra high vacuum: 10-9 to 10-12 Torr


            • CERN LHC: 1 x 10-10 Torr

            • Moon’s surface: 1 x 10-11 Torr

            • Deep Space 1 x 10-17 Torr = 0.000,000,000,000,000,01 Torr




          So we can see that the value of 1 x 10-17 Torr is associated with a place in "Deep Space" which is (probably) beyond that of the Moon.



          Let's see if we can figure out where the author is getting that number.



          According to the Wikipedia article on the interstellar medium (space between stars, far away from solar systems and other things):




          In all phases, the interstellar medium is extremely tenuous by terrestrial standards. In cool, dense regions of the ISM, matter is primarily in molecular form, and reaches number densities of 106 molecules per cm3 (1 million molecules per cm3). In hot, diffuse regions of the ISM, matter is primarily ionized, and the density may be as low as 10−4 ions per cm3. Compare this with a number density of roughly 1019 molecules per cm3 for air at sea level, and 1010 molecules per cm3 (10 billion molecules per cm3) for a laboratory high-vacuum chamber.




          It is harder to talk about pressure than density because pressure is related to both number density and temperature. The atmosphere is more than 10x hotter than interstellar medium, so let's look for a number density ratio of 1/10 of 1000 Torr versus 10^-17 torr, or a ratio of 10^19.



          If (according to Wikipedia) Earth's atmosphere has a density of 10^19 per cm^3, we're looking for a density of 1 per cm^3. Checking Wikipedia we can see that there are components of the interstellar medium with number densities between 10^6 and 10^-4.



          It looks like the value in the presentation a rough ballpark estimate, but isn't off by more than a handful of orders of magnitude ;-)




          How can such a vacuum coexist with the open system of earth’s atmosphere whereby debris from space can enter in?




          While these two pressures can coexist in the same universe, they don't coexist in proximity at all. The interstellar medium is very, very far away from Earth's atmosphere, on the order of a lightyear.



          Gravity keeps Earth's atmosphere nearby Earth, the solar system has gas produced by (and attracted by) the Sun's gravity. In interstellar space, there just isn't any source of gas, and what might have been there at one time has moved away, towards sources of gravity, over billions of years.






          share|improve this answer











          $endgroup$













          • $begingroup$
            Thank you for your response. Are you disputing the pressure on the moon also? Because if the pressure is out by a handful of magnitudes certainly between the moon and earth’s atmosphere there exist a vacuum of some sort at least as weak as a dyson vacuum cleaner. The notion that gravity holds the atmosphere in place but still is weak enough to allow gases to stratify depending on density or pressure is very difficult to wrap my head around. Not to mention that pressure requires something to press onto. What is the atmosphere pressing onto? The vacuum?
            $endgroup$
            – Autodidact
            1 hour ago












          • $begingroup$
            @Autodidact I have not disputed anything. I'm in general agreement with the powerpoint; within several orders of magnitude at least. The word "coexist" makes your question difficult to answer because you don't explain what you mean. They can coexist in the same universe, but not close to each other. I think a question about how the atmosphere ends up stratified in pressure due to gravity is a great one, but probably is better to ask in Earth Science SE or Physics SE.
            $endgroup$
            – uhoh
            1 hour ago






          • 1




            $begingroup$
            @Autodidact You may find several questions and answers like that in those sites already, best to read them before asking something that's been answered. Here is some related math, but there are probably better places to find a useful and head-wrappable explanation. en.wikipedia.org/wiki/Scale_height
            $endgroup$
            – uhoh
            1 hour ago








          • 1




            $begingroup$
            Thank you for the link. If this question is not asked in the correct stack, my sincerest apologies. Also my edit was not intended as a moving target, I didn’t want it dismissed. As for the atmosphere pressure, while the link provides a distance it doesn’t explain my inquiry, what is it pressing upon to generate the distance? That is a question to which I cannot seem to find an answer to. Gravity seems to be the answer but it’s powers are conflicting as I’ve pointed out. It’s sufficiently strong to resist a vacuum of 10^-11 but weak enough to let gas particles up 8.5 km up into the atmosphere.
            $endgroup$
            – Autodidact
            52 mins ago






          • 1




            $begingroup$
            The Moon kind of does have an atmosphere, but it's very thin, and its total mass is under 10 tonnes. See en.wikipedia.org/wiki/Atmosphere_of_the_Moon
            $endgroup$
            – PM 2Ring
            44 mins ago














          3












          3








          3





          $begingroup$

          update: This answer was written before the question was modified. I've tried to explain where a value like 10-17 Torr for deep space might come from, but it's since been dropped in lieu of 10^-11 Torr at the Moon, which is probably a better way to formulate the question.



          I think the answer is the same, two points very far away can have very different pressures. They can coexist in the same solar system, just not right next to each other. I think "Why doesn't the Moon have at least a small atmosphere?" could also be an excellent, but very different question.





          In a comment the OP links to the presentation VACUUM (There’s nothing to it… ) written from the perspective of an engineer in the semiconductor manufacturing industry.



          Slide 6 gives examples of vacuum levels in different situations:



          Going down:




          • Low vacuum: 760 Torr to 1 x 10-3 Torr


            • Vacuum cleaner: to 600 Torr

            • Thermos bottle 10-3 Torr



          • High vacuum: 10-3 to 10-9 Torr


            • Electron microscope

            • Ion Implanter
              – Evaporator
              – Sputterer



          • Ultra high vacuum: 10-9 to 10-12 Torr


            • CERN LHC: 1 x 10-10 Torr

            • Moon’s surface: 1 x 10-11 Torr

            • Deep Space 1 x 10-17 Torr = 0.000,000,000,000,000,01 Torr




          So we can see that the value of 1 x 10-17 Torr is associated with a place in "Deep Space" which is (probably) beyond that of the Moon.



          Let's see if we can figure out where the author is getting that number.



          According to the Wikipedia article on the interstellar medium (space between stars, far away from solar systems and other things):




          In all phases, the interstellar medium is extremely tenuous by terrestrial standards. In cool, dense regions of the ISM, matter is primarily in molecular form, and reaches number densities of 106 molecules per cm3 (1 million molecules per cm3). In hot, diffuse regions of the ISM, matter is primarily ionized, and the density may be as low as 10−4 ions per cm3. Compare this with a number density of roughly 1019 molecules per cm3 for air at sea level, and 1010 molecules per cm3 (10 billion molecules per cm3) for a laboratory high-vacuum chamber.




          It is harder to talk about pressure than density because pressure is related to both number density and temperature. The atmosphere is more than 10x hotter than interstellar medium, so let's look for a number density ratio of 1/10 of 1000 Torr versus 10^-17 torr, or a ratio of 10^19.



          If (according to Wikipedia) Earth's atmosphere has a density of 10^19 per cm^3, we're looking for a density of 1 per cm^3. Checking Wikipedia we can see that there are components of the interstellar medium with number densities between 10^6 and 10^-4.



          It looks like the value in the presentation a rough ballpark estimate, but isn't off by more than a handful of orders of magnitude ;-)




          How can such a vacuum coexist with the open system of earth’s atmosphere whereby debris from space can enter in?




          While these two pressures can coexist in the same universe, they don't coexist in proximity at all. The interstellar medium is very, very far away from Earth's atmosphere, on the order of a lightyear.



          Gravity keeps Earth's atmosphere nearby Earth, the solar system has gas produced by (and attracted by) the Sun's gravity. In interstellar space, there just isn't any source of gas, and what might have been there at one time has moved away, towards sources of gravity, over billions of years.






          share|improve this answer











          $endgroup$



          update: This answer was written before the question was modified. I've tried to explain where a value like 10-17 Torr for deep space might come from, but it's since been dropped in lieu of 10^-11 Torr at the Moon, which is probably a better way to formulate the question.



          I think the answer is the same, two points very far away can have very different pressures. They can coexist in the same solar system, just not right next to each other. I think "Why doesn't the Moon have at least a small atmosphere?" could also be an excellent, but very different question.





          In a comment the OP links to the presentation VACUUM (There’s nothing to it… ) written from the perspective of an engineer in the semiconductor manufacturing industry.



          Slide 6 gives examples of vacuum levels in different situations:



          Going down:




          • Low vacuum: 760 Torr to 1 x 10-3 Torr


            • Vacuum cleaner: to 600 Torr

            • Thermos bottle 10-3 Torr



          • High vacuum: 10-3 to 10-9 Torr


            • Electron microscope

            • Ion Implanter
              – Evaporator
              – Sputterer



          • Ultra high vacuum: 10-9 to 10-12 Torr


            • CERN LHC: 1 x 10-10 Torr

            • Moon’s surface: 1 x 10-11 Torr

            • Deep Space 1 x 10-17 Torr = 0.000,000,000,000,000,01 Torr




          So we can see that the value of 1 x 10-17 Torr is associated with a place in "Deep Space" which is (probably) beyond that of the Moon.



          Let's see if we can figure out where the author is getting that number.



          According to the Wikipedia article on the interstellar medium (space between stars, far away from solar systems and other things):




          In all phases, the interstellar medium is extremely tenuous by terrestrial standards. In cool, dense regions of the ISM, matter is primarily in molecular form, and reaches number densities of 106 molecules per cm3 (1 million molecules per cm3). In hot, diffuse regions of the ISM, matter is primarily ionized, and the density may be as low as 10−4 ions per cm3. Compare this with a number density of roughly 1019 molecules per cm3 for air at sea level, and 1010 molecules per cm3 (10 billion molecules per cm3) for a laboratory high-vacuum chamber.




          It is harder to talk about pressure than density because pressure is related to both number density and temperature. The atmosphere is more than 10x hotter than interstellar medium, so let's look for a number density ratio of 1/10 of 1000 Torr versus 10^-17 torr, or a ratio of 10^19.



          If (according to Wikipedia) Earth's atmosphere has a density of 10^19 per cm^3, we're looking for a density of 1 per cm^3. Checking Wikipedia we can see that there are components of the interstellar medium with number densities between 10^6 and 10^-4.



          It looks like the value in the presentation a rough ballpark estimate, but isn't off by more than a handful of orders of magnitude ;-)




          How can such a vacuum coexist with the open system of earth’s atmosphere whereby debris from space can enter in?




          While these two pressures can coexist in the same universe, they don't coexist in proximity at all. The interstellar medium is very, very far away from Earth's atmosphere, on the order of a lightyear.



          Gravity keeps Earth's atmosphere nearby Earth, the solar system has gas produced by (and attracted by) the Sun's gravity. In interstellar space, there just isn't any source of gas, and what might have been there at one time has moved away, towards sources of gravity, over billions of years.







          share|improve this answer














          share|improve this answer



          share|improve this answer








          edited 44 mins ago

























          answered 1 hour ago









          uhohuhoh

          6,02221761




          6,02221761












          • $begingroup$
            Thank you for your response. Are you disputing the pressure on the moon also? Because if the pressure is out by a handful of magnitudes certainly between the moon and earth’s atmosphere there exist a vacuum of some sort at least as weak as a dyson vacuum cleaner. The notion that gravity holds the atmosphere in place but still is weak enough to allow gases to stratify depending on density or pressure is very difficult to wrap my head around. Not to mention that pressure requires something to press onto. What is the atmosphere pressing onto? The vacuum?
            $endgroup$
            – Autodidact
            1 hour ago












          • $begingroup$
            @Autodidact I have not disputed anything. I'm in general agreement with the powerpoint; within several orders of magnitude at least. The word "coexist" makes your question difficult to answer because you don't explain what you mean. They can coexist in the same universe, but not close to each other. I think a question about how the atmosphere ends up stratified in pressure due to gravity is a great one, but probably is better to ask in Earth Science SE or Physics SE.
            $endgroup$
            – uhoh
            1 hour ago






          • 1




            $begingroup$
            @Autodidact You may find several questions and answers like that in those sites already, best to read them before asking something that's been answered. Here is some related math, but there are probably better places to find a useful and head-wrappable explanation. en.wikipedia.org/wiki/Scale_height
            $endgroup$
            – uhoh
            1 hour ago








          • 1




            $begingroup$
            Thank you for the link. If this question is not asked in the correct stack, my sincerest apologies. Also my edit was not intended as a moving target, I didn’t want it dismissed. As for the atmosphere pressure, while the link provides a distance it doesn’t explain my inquiry, what is it pressing upon to generate the distance? That is a question to which I cannot seem to find an answer to. Gravity seems to be the answer but it’s powers are conflicting as I’ve pointed out. It’s sufficiently strong to resist a vacuum of 10^-11 but weak enough to let gas particles up 8.5 km up into the atmosphere.
            $endgroup$
            – Autodidact
            52 mins ago






          • 1




            $begingroup$
            The Moon kind of does have an atmosphere, but it's very thin, and its total mass is under 10 tonnes. See en.wikipedia.org/wiki/Atmosphere_of_the_Moon
            $endgroup$
            – PM 2Ring
            44 mins ago


















          • $begingroup$
            Thank you for your response. Are you disputing the pressure on the moon also? Because if the pressure is out by a handful of magnitudes certainly between the moon and earth’s atmosphere there exist a vacuum of some sort at least as weak as a dyson vacuum cleaner. The notion that gravity holds the atmosphere in place but still is weak enough to allow gases to stratify depending on density or pressure is very difficult to wrap my head around. Not to mention that pressure requires something to press onto. What is the atmosphere pressing onto? The vacuum?
            $endgroup$
            – Autodidact
            1 hour ago












          • $begingroup$
            @Autodidact I have not disputed anything. I'm in general agreement with the powerpoint; within several orders of magnitude at least. The word "coexist" makes your question difficult to answer because you don't explain what you mean. They can coexist in the same universe, but not close to each other. I think a question about how the atmosphere ends up stratified in pressure due to gravity is a great one, but probably is better to ask in Earth Science SE or Physics SE.
            $endgroup$
            – uhoh
            1 hour ago






          • 1




            $begingroup$
            @Autodidact You may find several questions and answers like that in those sites already, best to read them before asking something that's been answered. Here is some related math, but there are probably better places to find a useful and head-wrappable explanation. en.wikipedia.org/wiki/Scale_height
            $endgroup$
            – uhoh
            1 hour ago








          • 1




            $begingroup$
            Thank you for the link. If this question is not asked in the correct stack, my sincerest apologies. Also my edit was not intended as a moving target, I didn’t want it dismissed. As for the atmosphere pressure, while the link provides a distance it doesn’t explain my inquiry, what is it pressing upon to generate the distance? That is a question to which I cannot seem to find an answer to. Gravity seems to be the answer but it’s powers are conflicting as I’ve pointed out. It’s sufficiently strong to resist a vacuum of 10^-11 but weak enough to let gas particles up 8.5 km up into the atmosphere.
            $endgroup$
            – Autodidact
            52 mins ago






          • 1




            $begingroup$
            The Moon kind of does have an atmosphere, but it's very thin, and its total mass is under 10 tonnes. See en.wikipedia.org/wiki/Atmosphere_of_the_Moon
            $endgroup$
            – PM 2Ring
            44 mins ago
















          $begingroup$
          Thank you for your response. Are you disputing the pressure on the moon also? Because if the pressure is out by a handful of magnitudes certainly between the moon and earth’s atmosphere there exist a vacuum of some sort at least as weak as a dyson vacuum cleaner. The notion that gravity holds the atmosphere in place but still is weak enough to allow gases to stratify depending on density or pressure is very difficult to wrap my head around. Not to mention that pressure requires something to press onto. What is the atmosphere pressing onto? The vacuum?
          $endgroup$
          – Autodidact
          1 hour ago






          $begingroup$
          Thank you for your response. Are you disputing the pressure on the moon also? Because if the pressure is out by a handful of magnitudes certainly between the moon and earth’s atmosphere there exist a vacuum of some sort at least as weak as a dyson vacuum cleaner. The notion that gravity holds the atmosphere in place but still is weak enough to allow gases to stratify depending on density or pressure is very difficult to wrap my head around. Not to mention that pressure requires something to press onto. What is the atmosphere pressing onto? The vacuum?
          $endgroup$
          – Autodidact
          1 hour ago














          $begingroup$
          @Autodidact I have not disputed anything. I'm in general agreement with the powerpoint; within several orders of magnitude at least. The word "coexist" makes your question difficult to answer because you don't explain what you mean. They can coexist in the same universe, but not close to each other. I think a question about how the atmosphere ends up stratified in pressure due to gravity is a great one, but probably is better to ask in Earth Science SE or Physics SE.
          $endgroup$
          – uhoh
          1 hour ago




          $begingroup$
          @Autodidact I have not disputed anything. I'm in general agreement with the powerpoint; within several orders of magnitude at least. The word "coexist" makes your question difficult to answer because you don't explain what you mean. They can coexist in the same universe, but not close to each other. I think a question about how the atmosphere ends up stratified in pressure due to gravity is a great one, but probably is better to ask in Earth Science SE or Physics SE.
          $endgroup$
          – uhoh
          1 hour ago




          1




          1




          $begingroup$
          @Autodidact You may find several questions and answers like that in those sites already, best to read them before asking something that's been answered. Here is some related math, but there are probably better places to find a useful and head-wrappable explanation. en.wikipedia.org/wiki/Scale_height
          $endgroup$
          – uhoh
          1 hour ago






          $begingroup$
          @Autodidact You may find several questions and answers like that in those sites already, best to read them before asking something that's been answered. Here is some related math, but there are probably better places to find a useful and head-wrappable explanation. en.wikipedia.org/wiki/Scale_height
          $endgroup$
          – uhoh
          1 hour ago






          1




          1




          $begingroup$
          Thank you for the link. If this question is not asked in the correct stack, my sincerest apologies. Also my edit was not intended as a moving target, I didn’t want it dismissed. As for the atmosphere pressure, while the link provides a distance it doesn’t explain my inquiry, what is it pressing upon to generate the distance? That is a question to which I cannot seem to find an answer to. Gravity seems to be the answer but it’s powers are conflicting as I’ve pointed out. It’s sufficiently strong to resist a vacuum of 10^-11 but weak enough to let gas particles up 8.5 km up into the atmosphere.
          $endgroup$
          – Autodidact
          52 mins ago




          $begingroup$
          Thank you for the link. If this question is not asked in the correct stack, my sincerest apologies. Also my edit was not intended as a moving target, I didn’t want it dismissed. As for the atmosphere pressure, while the link provides a distance it doesn’t explain my inquiry, what is it pressing upon to generate the distance? That is a question to which I cannot seem to find an answer to. Gravity seems to be the answer but it’s powers are conflicting as I’ve pointed out. It’s sufficiently strong to resist a vacuum of 10^-11 but weak enough to let gas particles up 8.5 km up into the atmosphere.
          $endgroup$
          – Autodidact
          52 mins ago




          1




          1




          $begingroup$
          The Moon kind of does have an atmosphere, but it's very thin, and its total mass is under 10 tonnes. See en.wikipedia.org/wiki/Atmosphere_of_the_Moon
          $endgroup$
          – PM 2Ring
          44 mins ago




          $begingroup$
          The Moon kind of does have an atmosphere, but it's very thin, and its total mass is under 10 tonnes. See en.wikipedia.org/wiki/Atmosphere_of_the_Moon
          $endgroup$
          – PM 2Ring
          44 mins ago










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