Talk:Vacuum
From Wikipedia, the free encyclopedia
 |
This article is a former featured article candidate. Please view its sub-page to see why the nomination failed. For older candidates, please check the archive. |
 |
Vacuum has had a peer review by Wikipedia editors which is now archived. It may contain ideas you can use to improve this article. |
 |
To-do list for Vacuum: | edit · history · watch · refresh |
|---|---|---|
|
||
| Priority 1 (top) | ||
 Archives |
|---|
A number of issues of continuing interest can be found in the archive. If you would like to add to these discussions, please consult the archive first to find out what others have said, and then post your reply here. Some of these interesting topics are
- Should we use SI units or Torrs?
- What is the definition of vacuum? Is perfect vacuum possible?
- The temperature of outer space should be clarified.
Contents |
[edit] Units
Ytrottier/Yannick, who talks on the archived pages about "torr" being some "industry standard", and who phrases the choices above as between "SI units" and "Torrs", maybe ought to get out more, see a bit of the rest of the world.
At least, you might venture out as far as your local Canadian Tire store, where you might see if they have their Pro Vacuum-Pressure Tester on hand.[1]
Scales in two sets of units—but neither of them torrs.
Part of my point, of course, is that Yannick is using a weird notion of the existence of an "industry standard" for a concept, a physical property, that is quite general in nature and which crops up in many different fields of activity.
BTW, Torrs shouldn't be capitalized if it has an "s" at the end; "Torr" (uppercase T) is the symbol for "torr" (lowercase t), and symbols aren't changed in the plural. Gene Nygaard 15:20, 15 April 2006 (UTC)
- Hi, Gene. Thanks for your comments, but please stay polite. I am well aware that the automotive world uses psi's and pascals rather than torrs, but cars are a very small and low-tech fringe of the world of vacuum. I realize that the debate over units is not over, and that's why I was careful to leave a note about it on the main talk page when archiving the discussion. But I have worked with a wide variety of industrial and scientific vacuum equipment and I've done my research for this article - most of those footnotes are from me. The standard unit I saw pretty much everywhere is the torr. And yes, I am Canadian, and I've taken apart my motorcycle engine and put it back together a couple of times with Mastercraft tools.--Yannick 01:16, 16 April 2006 (UTC)
What about the Marine Engineering world? I'm quite aware the practical side of such a use is quite low-tech, but ever since ships used steam engines with condensing turbines, they more or less operated with the condenser at a vacuum (measured in inches of mercury, often with the use of steam "air ejectors", basically eductor pumps with the working fluid being saturated steam). On the more modern diesel engines, the engine crankcases are kept at a slight vacuum due to blowers, designed to prevent crankcase explosions, and such a vacuum is usually measured in inches of water (using a manometer). I know I'm really only discussing American ships, but British ships were built this way as well. --Hengineer 21:36, 16 July 2006 (UTC)
[edit] Vacuum
After months of arduous work, we have nothing to show for it. Seriously folks, I think we've done a good job on this page, it's quite stable, and nearly ready to go for FAC. Your constructive criticism would be appreciated.--Yannick 04:11, 4 April 2006 (UTC)
- Lead can be safely doubled or tripled in size, at the moment it's pretty light. MoS is rather strict when it comes to bolding: unbold things like 'perfect vacumm' and turn them into ilinks. I'd recommend moving 'Historical interpretation' section to the begining - history often goes first and the current 'Vacuum Quality' section is rather to technical and can scare away people. I'd recommend expanding 'Uses' section - it is quite short now. Keep up the good work :)--Piotr Konieczny aka Prokonsul Piotrus Talk 21:49, 4 April 2006 (UTC)
- :) Yes, I think, the lead section should be expanded and probably reworded, e.g. a reference in it seems to be inappropriate to me. Some of the sections should not just list characteristics with numerical values, but rather be description-style, in particular "Properties" section doesn't look good for me. But as concerns comprehensiveness, I see the article to be very good and helpful. Cmapm 13:57, 5 April 2006 (UTC)
Comment Techy stuff should go down the bottom, move Vacuum Quality / Measurement / Properties to the end, just before notes. --PopUpPirate 22:57, 6 April 2006 (UTC)
Thank you for your comments, all of you. I've working up close with this article for a few months, and had lost track of some of the wider perspective.
- I agree with your general comments to expand the lead and move technical details to the end, but I disagree on some of the specifics. I don't really want to move 'Historical interpretation' to the begining because I have concerns about its completeness and accuracy in its current form. The philosophical debates about vacuum were much more complicated than is currently represented. However, maybe 'Uses' and 'Vacuum pumping' would be suitable first sections? I had placed 'Vacuum quality' and 'Measurement' at the top to explain the quantification of partial vacuum early on, but this can probably be done in the expanded lead section.
- A minor edit war and arguments on the discussion page indicate that many users have trouble understanding the physical impossibility of perfect vacuum, despite explanations in the article. That's why I put a reference in the lead section. I'm not sure how best to deal with that. Your suggestions are appreciated.
- I reviewed the Wikipedia:Manual of Style and did not find it so strict regarding bolding. In fact, it seems to require bolding of alternate article titles such as "perfect vacuum". The legibility section says "Make judicious use of devices such as bulleted lists and bolding," but then it points to an outside article that seems to recommend bolding of the kind used in the Vacuum article.
--Yannick 02:47, 10 April 2006 (UTC)
OK, I just tripled the size of the lead section per your suggestions, and I think this should allow the restructuring you have recommended.--Yannick 03:57, 12 April 2006 (UTC)
I reordered the sections to try to meet suggestions. Please comment.--Yannick 03:17, 25 April 2006 (UTC)
[edit] Electrical properties of vacuum
Hi, the article at present discusses the electrical properties of vacuum which make "electron microscopes and vacuum tubes possible". This is true, and results from the fact that it there is nothing (or at least less) to impede the flow of electrons fired from one end of a device to the other. There is another electrical property of vacuum as well, and this is its ability to withstand a high electric field without electrical breakdown. In fact, the electrical insulating property (or dielectric strength) of high vacuum is only limited to the point where electrons are literally pulled out of the conductors. It is therefore used in several specialised high voltage applications. Not sure if I am explaining myself too clearly here, but this is an electrical property of vacuum that is separate from its ability to form electron guns, and so on. --BillC 20:40, 8 May 2006 (UTC)
- There's a discussion about the insulating quality of vacuums on Talk:Electrical insulation DMacks 21:20, 8 May 2006 (UTC)
[edit] Historical interpretation
The article states that "Plato was right". Plato may have been right and may have been wrong. Are we forgetting that all of science, including quantum mechanics, is based on theory? It is at best an approximation of reality, and it is certainly not correct. I feel this sentence should be removed from the article as it implies we know the quantum mechanical interpretation of the vacuum to be the correct one - we don't, it is only our current theory. —The preceding unsigned comment was added by Corp1117 (talk • contribs) .
[edit] Perfect vaccuum exists or not?
"space can never be perfectly empty. A perfect vacuum with a gaseous pressure of absolute zero is a philosophical concept with no physical reality, not least because quantum theory predicts that no volume of space is perfectly empty in this way." -- This is probably a quibble, but any volume of space between atoms of gas has a gaseous pressure of zero, right? Although particles are produced by the decay of the vacuum, they aren't technically "a gas". -- 201.51.236.252 14:51, 7 November 2006 (UTC)
No. Read the Vacuum#Quantum-mechanical definition section for a full explanation. The "gaseous pressure between atoms" may be undefined, depending on your definitions, but it is not zero.--Yannick 23:42, 7 November 2006 (UTC)
[edit] Vacuum Graphs
I am a young and inexperienced Mechanical engineer. I would like to know if anyone out there could tell me where I can find a vacuum graph (if it exists). I know that when creating a vacuum, flow rate out of the pump is high initially and it slowly decreases as the pressure inside the control volume decreases. I think that this is exponential. I would like to see a graph that links Pressure, Time, and flowrate within a system under that process of decompression (vacuum). Greatly appreciate all your help. Cheers, --203.94.168.206
The relationship between pressure, time, and flowrate is different for every pump, chamber, and contents under vacuum, so you will have to develop your own graph for your own system. However, if you just want some examples, go to any vacuum pump manufacturer and lookup their specifications. Most of them provide graphs of pumping speed versus pressure. (example) You can learn a bit more about the math and how to relate time to these by looking at our vacuum pump article.--Yannick 14:16, 12 November 2006 (UTC)
[edit] Solar Sails
"The idea of using this wind with a solar sail has been proposed for interplanetary travel." I believe that to be incorrect. Also contrary to what it says on the Solar sail page. "Another false claim is that solar sails capture energy primarily from the "solar wind": high speed charged particles emitted from the sun. These particles would impart a small amount of momentum upon striking the sail, but this effect would be small compared to the force due to radiation pressure from light reflected from the sail. The force due to light pressure is about 100 times as strong as that due to solar wind."
A solar sail uses the momentum of photons by reflecting them off its surface rather than the energy captured when a charged particle collides with it. Underlord 22:54, 10 December 2006 (UTC)
[edit] Density of intergalactic space
What is it? This article says: "But no vacuum is perfect, not even in interstellar space, where there are a few hydrogen atoms per cubic centimeter"
Whilst the Intergalactic Space article(http://en.wikipedia.org/wiki/Intergalactic_space) says: "The average density of the Universe is less than one atom per cubic meter."
Are these contradictory or is there some explanation that accounts for both statements? Even if there is, doesn't it seem more reasonable to quote the lower number ie "one atom per cubic meter"(assuming that is correct) when making a comparison to a perfect vacuum? —The preceding unsigned comment was added by 220.239.143.19 (talk) 14:01, 11 January 2007 (UTC).
