Science desk | ||
---|---|---|
< August 28 | << Jul | August | Sep >> | August 30 > |
Welcome to the Wikipedia Science Reference Desk Archives |
---|
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages. |
The caption on image 6 of this image gallery about Kepler-47 reads: "This screenshot from a NASA animation shows the orbital paths taken by the two known planets in the Kepler-47 system, which both orbit the same two stars." That last part seems intriguing to me. Do we know of an example where two planets in the same system orbit different stars? Dismas| (talk) 00:26, 29 August 2012 (UTC)
From the superheating article: "Superheating is achieved by heating a homogeneous substance in a clean container, free of nucleation sites, while taking care not to disturb the liquid. ... Water is said to "boil" when bubbles of water vapor grow without bound, bursting at the surface. For a vapor bubble to expand, the temperature must be high enough that the vapor pressure exceeds the ambient pressure – the atmospheric pressure, primarily. Below that temperature, a water vapor bubble will shrink and vanish. Superheating is an exception to this simple rule: a liquid is sometimes observed not to boil even though its vapor pressure does exceed the ambient pressure. The cause is an additional force, the surface tension, which suppresses the growth of bubbles."
I have three questions: 1) what are the usual nucleation sites in a "regular" pot of water that cause it to boil at 100C? Irregularities in the surface of the pot which trap pockets of air are one. Are there any others? 2) how do these nucleation sites actually promote bubble-making. (I don't see how trapping air will make it easier to form bubbles). 3) why do these bubbles only need to overcome the ambient pressure, and not the ambient pressure + pressure due to surface tension?
Thanks. 65.92.7.148 ( talk) 00:57, 29 August 2012 (UTC)
Also, in bubble chambers, why doesn't the sudden formation of bubbles cause the whole thing to boil? 65.92.7.148 ( talk) 01:01, 29 August 2012 (UTC)
See symmetry breaking. Any sort of balanced high-energy system will collapse given the slightest chance to do so. You don't need to shake a balanced pin very hard to get it to fall over. μηδείς ( talk) 01:30, 30 August 2012 (UTC)
Hi, I'm looking for the Curiosity Rover's flight path, something similar to this:
I checked the
Mars Science Laboratory article and some of the related articles (like the timeline), but I can't seem to find it. Basically, I want to see the placement of the Earth & Mars during the takeoff & landing, and view the orbit of the planets while also keeping track of Curiosity's position, all of this relative to the Sun.
A snapshot of the celestial bodies' positions at takeoff, and a separate snapshot of the celestial bodies' at landing, would be helpful, but what I'm looking for is either an animation, or month by month snapshots at least.
Any help is appreciated, thanks!-- 99.179.20.157 ( talk) 03:48, 29 August 2012 (UTC)
I've been reading these helpdesk answers for years and there are such brilliant replies. Which of the 'regulars' here actually work as scientists or as teachers/professors? I'm not looking for stats but just some short replies from the regulars. Thanks. Sandman30s ( talk) 06:57, 29 August 2012 (UTC)
Normally when general anaesthesia is administered to a patient, there is a lot of preparation before hand such as assessments, emptying bowels, ensurin the patient doesn't eat or drink before hand etc but how is all this done in emergency surgery in life threatening cases where patients are taken straight to surgery from emergency. Also are relaxants etc used before general anaesthesia to relax patients? Clover345 ( talk) 10:56, 29 August 2012 (UTC)
Carl Linnaeus Belived In The Fixity Of Species By Divine Creation And Died 31 Years Before Darwin Was Born. Why Then Does The Taxonomic System That Bears His Name Support Darwin's Theory Of Common — Preceding unsigned comment added by PAOH200 ( talk • contribs) 13:47, 29 August 2012 (UTC)
Darwinism is true, and the Linnean system is coherent with the facts. It doesn't intentionally support as in "argue for" Darwinism.. rather, the truth coheres. μηδείς ( talk) 01:27, 30 August 2012 (UTC)
These days, Charles Bolden and Will.i.am are amusing themselves by making their voices come out of a speaker on Curiosity on Mars. But Mars' atmosphere is very thin. I haven't been able to find out what the speaker's volume settings are, but if they are about strong enough such that on Earth, the volume would be 60 dB, about as loud as conversation in restaurant, office, background music, Air conditioning unit at 100 ft ( source) at 3m distance from it, how loud in dB would it be about 3m away from Curiosity on the surface of Mars to a human who miraculously could survive without a helmet on? 20.137.18.53 ( talk) 14:38, 29 August 2012 (UTC)
Hi,
Does the Mars Rover 'Curiosity' have a microphone on board? If not why wasn't it planned for since I vaguely remember some scientists(Perhaps Carl Sagan) hoping to put a microphone on a Mars probe to hear the sounds of the Martian winds? — Preceding unsigned comment added by Gulielmus estavius ( talk • contribs) 17:05, 29 August 2012 (UTC)
I read this article which suggests lesbians could create one day create sperm from their own bone marrow cells so they would be able to have children. However, I intuit that they would only be able to produce girls. If those girls were lesbians too, I could see a self-sustaining "Amazon" type of society, without the need for men. Which makes me think, why did mammals evolve separate sexes anyway? Couldn't you have meiosis without the need for separate sexes? After all, many plants have male and female gametophytes coming from the same plant/sporophyte. It seems to me you could have twice the reproductive capacity without the need for "dedicated" males.
I understand the selfish gene argument for why the sex ratios are 1:1, but that doesn't explain how the separate sexes got created. What was the evolutionary incentive for initiating separate-sex "sporophytes"? If selfish genes could create one parasitic class which cannot directly reproduce, why didn't they end up creating many? 71.207.151.227 ( talk) 17:12, 29 August 2012 (UTC)
As soon as there is some sort of heritable variability in sex cells, the "male" strategy of small and motile will become hugely successful compared to medium sized and immobile, since "sperm" will be much cheaper to produce in quantity and more likely to "score" than medium sized sex cells. Once sperm become ubiquitous, the rare egg will become a much more valuable commodity, and its increased size will increase viability, while its selectiveness among sperm (sexual selection) will increase the quality of offspring produced. First the male strategy is highly successful, and then presence of males makes the female strategy itself successful, leading two two stable "solutions" to the sex problem. μηδείς ( talk) 01:24, 30 August 2012 (UTC)
It is well known that human chromosone 2 is just a fused version of primate chromosomes. But I have problems understanding how the new lineage that would eventually lead to modern humans actually propagated. If one individual had the chromosomal mutation, how could he even mate if the surrounding population had a different number of chromosomes? Or is it more likely that more than one individual had the same random chromosomal mutation? -- Ghostexorcist ( talk) 17:34, 29 August 2012 (UTC)
According to Rubella, the first administration of the MMR vaccine usually occurs around 12-18 months, but I wonder if a baby experiences the virus before that vaccination, does the baby's immune system get any "education" on how to combat future exposures from that? I'm not talking about CRS or an extremely young newborn, and of course this is not to say that that would preclude vaccination (that's not even my question). I was just wondering the biological question of whether or not an as-yet non-vaccinated human gets any immunological benefit after having gone through it and survived it in the specific case of Rubella. 20.137.18.53 ( talk) 20:29, 29 August 2012 (UTC)
Science desk | ||
---|---|---|
< August 28 | << Jul | August | Sep >> | August 30 > |
Welcome to the Wikipedia Science Reference Desk Archives |
---|
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages. |
The caption on image 6 of this image gallery about Kepler-47 reads: "This screenshot from a NASA animation shows the orbital paths taken by the two known planets in the Kepler-47 system, which both orbit the same two stars." That last part seems intriguing to me. Do we know of an example where two planets in the same system orbit different stars? Dismas| (talk) 00:26, 29 August 2012 (UTC)
From the superheating article: "Superheating is achieved by heating a homogeneous substance in a clean container, free of nucleation sites, while taking care not to disturb the liquid. ... Water is said to "boil" when bubbles of water vapor grow without bound, bursting at the surface. For a vapor bubble to expand, the temperature must be high enough that the vapor pressure exceeds the ambient pressure – the atmospheric pressure, primarily. Below that temperature, a water vapor bubble will shrink and vanish. Superheating is an exception to this simple rule: a liquid is sometimes observed not to boil even though its vapor pressure does exceed the ambient pressure. The cause is an additional force, the surface tension, which suppresses the growth of bubbles."
I have three questions: 1) what are the usual nucleation sites in a "regular" pot of water that cause it to boil at 100C? Irregularities in the surface of the pot which trap pockets of air are one. Are there any others? 2) how do these nucleation sites actually promote bubble-making. (I don't see how trapping air will make it easier to form bubbles). 3) why do these bubbles only need to overcome the ambient pressure, and not the ambient pressure + pressure due to surface tension?
Thanks. 65.92.7.148 ( talk) 00:57, 29 August 2012 (UTC)
Also, in bubble chambers, why doesn't the sudden formation of bubbles cause the whole thing to boil? 65.92.7.148 ( talk) 01:01, 29 August 2012 (UTC)
See symmetry breaking. Any sort of balanced high-energy system will collapse given the slightest chance to do so. You don't need to shake a balanced pin very hard to get it to fall over. μηδείς ( talk) 01:30, 30 August 2012 (UTC)
Hi, I'm looking for the Curiosity Rover's flight path, something similar to this:
I checked the
Mars Science Laboratory article and some of the related articles (like the timeline), but I can't seem to find it. Basically, I want to see the placement of the Earth & Mars during the takeoff & landing, and view the orbit of the planets while also keeping track of Curiosity's position, all of this relative to the Sun.
A snapshot of the celestial bodies' positions at takeoff, and a separate snapshot of the celestial bodies' at landing, would be helpful, but what I'm looking for is either an animation, or month by month snapshots at least.
Any help is appreciated, thanks!-- 99.179.20.157 ( talk) 03:48, 29 August 2012 (UTC)
I've been reading these helpdesk answers for years and there are such brilliant replies. Which of the 'regulars' here actually work as scientists or as teachers/professors? I'm not looking for stats but just some short replies from the regulars. Thanks. Sandman30s ( talk) 06:57, 29 August 2012 (UTC)
Normally when general anaesthesia is administered to a patient, there is a lot of preparation before hand such as assessments, emptying bowels, ensurin the patient doesn't eat or drink before hand etc but how is all this done in emergency surgery in life threatening cases where patients are taken straight to surgery from emergency. Also are relaxants etc used before general anaesthesia to relax patients? Clover345 ( talk) 10:56, 29 August 2012 (UTC)
Carl Linnaeus Belived In The Fixity Of Species By Divine Creation And Died 31 Years Before Darwin Was Born. Why Then Does The Taxonomic System That Bears His Name Support Darwin's Theory Of Common — Preceding unsigned comment added by PAOH200 ( talk • contribs) 13:47, 29 August 2012 (UTC)
Darwinism is true, and the Linnean system is coherent with the facts. It doesn't intentionally support as in "argue for" Darwinism.. rather, the truth coheres. μηδείς ( talk) 01:27, 30 August 2012 (UTC)
These days, Charles Bolden and Will.i.am are amusing themselves by making their voices come out of a speaker on Curiosity on Mars. But Mars' atmosphere is very thin. I haven't been able to find out what the speaker's volume settings are, but if they are about strong enough such that on Earth, the volume would be 60 dB, about as loud as conversation in restaurant, office, background music, Air conditioning unit at 100 ft ( source) at 3m distance from it, how loud in dB would it be about 3m away from Curiosity on the surface of Mars to a human who miraculously could survive without a helmet on? 20.137.18.53 ( talk) 14:38, 29 August 2012 (UTC)
Hi,
Does the Mars Rover 'Curiosity' have a microphone on board? If not why wasn't it planned for since I vaguely remember some scientists(Perhaps Carl Sagan) hoping to put a microphone on a Mars probe to hear the sounds of the Martian winds? — Preceding unsigned comment added by Gulielmus estavius ( talk • contribs) 17:05, 29 August 2012 (UTC)
I read this article which suggests lesbians could create one day create sperm from their own bone marrow cells so they would be able to have children. However, I intuit that they would only be able to produce girls. If those girls were lesbians too, I could see a self-sustaining "Amazon" type of society, without the need for men. Which makes me think, why did mammals evolve separate sexes anyway? Couldn't you have meiosis without the need for separate sexes? After all, many plants have male and female gametophytes coming from the same plant/sporophyte. It seems to me you could have twice the reproductive capacity without the need for "dedicated" males.
I understand the selfish gene argument for why the sex ratios are 1:1, but that doesn't explain how the separate sexes got created. What was the evolutionary incentive for initiating separate-sex "sporophytes"? If selfish genes could create one parasitic class which cannot directly reproduce, why didn't they end up creating many? 71.207.151.227 ( talk) 17:12, 29 August 2012 (UTC)
As soon as there is some sort of heritable variability in sex cells, the "male" strategy of small and motile will become hugely successful compared to medium sized and immobile, since "sperm" will be much cheaper to produce in quantity and more likely to "score" than medium sized sex cells. Once sperm become ubiquitous, the rare egg will become a much more valuable commodity, and its increased size will increase viability, while its selectiveness among sperm (sexual selection) will increase the quality of offspring produced. First the male strategy is highly successful, and then presence of males makes the female strategy itself successful, leading two two stable "solutions" to the sex problem. μηδείς ( talk) 01:24, 30 August 2012 (UTC)
It is well known that human chromosone 2 is just a fused version of primate chromosomes. But I have problems understanding how the new lineage that would eventually lead to modern humans actually propagated. If one individual had the chromosomal mutation, how could he even mate if the surrounding population had a different number of chromosomes? Or is it more likely that more than one individual had the same random chromosomal mutation? -- Ghostexorcist ( talk) 17:34, 29 August 2012 (UTC)
According to Rubella, the first administration of the MMR vaccine usually occurs around 12-18 months, but I wonder if a baby experiences the virus before that vaccination, does the baby's immune system get any "education" on how to combat future exposures from that? I'm not talking about CRS or an extremely young newborn, and of course this is not to say that that would preclude vaccination (that's not even my question). I was just wondering the biological question of whether or not an as-yet non-vaccinated human gets any immunological benefit after having gone through it and survived it in the specific case of Rubella. 20.137.18.53 ( talk) 20:29, 29 August 2012 (UTC)