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I realise that the complexities of the ocean conveyor are incredibly complex, and that any answers to this may be guesses at best. I read "Shutdown of thermohaline circulation" which varies from 5000 years (citatation needed) to just 2-3 years (especially from ice core data) for the Earth to swap to a full Ice Age. Scientific experiments currently point to a dramatic and exponential slowing of the conveyor, but again we don't know enough to say, "Well going by this in 7 years it will have stopped and we'll be in Ice Age".
But we do know that salinity in the water seems to drive it, and it's a very finely balanced system, which has numerous times in the past swapped state.
Given that we seem to be in the middle of such a swap, could the enormous amount of oil (which continues to rise with no current idea of how to stop it) stop the ocean conveyor? If it is so finely balanced and mere salinity of the water is extremely important, then wouldn't a Gulf full of crude oil be enough to stop the whole thing quickly? Could we be in ice age in 2010? I'll be very happy for any experts to shoot that idea down ..
Prob'ly not -- the oil slick (as bad as it is) only covers a fairly small part of the Gulf's surface, so its effect on salinity is pretty insignificant. Also keep in mind that a large part of the oil is in underwater plumes, which have no effect on evaporation. Of course this is just a non-expert opinion from a reg'lar schmo who works at a refinery while taking evening classes at the university and writing adventure novels on weekends, and who knows a lot about oil refining but not much about ocean currents. FWiW 67.170.215.166 (talk) 01:57, 6 June 2010 (UTC)[reply]
The volume of the "enormous amount of oil spilled" in the "gulf full of crude oil" at the latest high limit for the leak rate of 19,000 barrels/day (USGS)is about what percent of the volume of water in the gulf, where a cubic meter=about 6.3 barrels of oil? I get about .000000006%. Edison (talk) 03:12, 6 June 2010 (UTC)[reply]
I have a duct which conveys air under pressure. I have to create some holes in it for measurement. The holes will be larger than conventional ones - maybe 10 - 25mm in diameter. Can anyone suggest some easy ways of plugging them after I have finished?
Thanks —Preceding unsigned comment added by 122.175.80.243 (talk) 04:27, 6 June 2010 (UTC)[reply]
What kind of pressure are we talking about? If it's fairly light pressure, duct tape on the inside of the duct might be easiest (maybe lain over two-inch cardboard or plastic circles for a bit of stiffness). duct tape around the outside might be sufficient as well, but it's ugly and not as strong. --Ludwigs204:44, 6 June 2010 (UTC)[reply]
As Ludwigs2 said we will need to know what sort of pressure the air is under before we can offer sensible answers, as depending on the pressure solutions will range from duct tape on the outside as mentioned above to things involving welding and steel plates. Another thing - is your only access to the inside of the duct through the holes, or can you reach the inside of the holes to e.g. apply patches? Equisetum (talk | email | contributions) 11:08, 6 June 2010 (UTC)[reply]
Duct tape can eventually fail. Metal tape with mastic like is used around flat roofs will deal with most problems with air conditioning ducts. For something this small just gluing something on it might do the job. Dmcq (talk) 12:35, 6 June 2010 (UTC)[reply]
Speed tape. In the UK I think it's just called "aluminium tape" (it's not just coated with aluminium, there's a Al foil as well) - it's definately more suitable for ducting that 'duck tape' especially in terms of gas resistance.77.86.124.76 (talk) 15:15, 6 June 2010 (UTC)[reply]
This is for a pneumatic conveying system so pressure will be fairly large (~8 kPa). It is a negative pressure (suction) so I guess taping (IF that is possible) would be done on the outside (right?). No the only access to the inside is through the holes. Any convenient method to plug it? Thanks —Preceding unsigned comment added by 122.175.80.243 (talk) 14:32, 7 June 2010 (UTC)[reply]
The ultimate fix would be to weld or glue a cylindrical or semi-cylindrical patch over the hole. This could be made of the same material as the tube itself. Using a large enough length of 'patch' would give you plenty of contact area to get an airtight seal over. SteveBaker (talk) 19:07, 7 June 2010 (UTC)[reply]
25mm hole with the pressure inside the duct being 8 kPa below atmospheric? Stick a piece of cardboard or flexible plastic over the hole and tape it in place. The pressure difference will seal the patch against the hole, while the tape will keep it from sliding around. --Carnildo (talk) 01:52, 10 June 2010 (UTC)[reply]
Lee Smollin: author of "baby universe" book, adversary of multiverse? huh?
Lee Smolin wrote a book advocating (or maybe just describing the theory of?) "baby universes." Years later, in a celebrated comment, he said "This universe is the only one there is." I can't figure out if this means he abandoned the baby universe theory altogether, or if he was defining "universe" to mean "the universe that contains all the baby universes." Does anybody know how Smolin's two positions relate to each other? 63.17.74.45 (talk) 08:38, 6 June 2010 (UTC)[reply]
I don't, but note that one was written and another spoken, there's often quite a difference between what people are prepared to say and what they will write, my guess the the book was hypothesising.87.102.43.94 (talk) 13:39, 6 June 2010 (UTC)[reply]
They're both in print, the latter in this article (requires a login which you can get here). He evidently means "the universe that contains all the baby universes", making it a rather content-free statement as far as I can tell (though he seems to think otherwise). -- BenRG (talk) 19:32, 6 June 2010 (UTC)[reply]
I heard yesterday on the BBC Radio World Service that I was listening to while playing World of Warcraft, that the Cassini probe has discovered what could be life on Titan, due to certain gasses in the atmosphere being absorbed, or not reaching the serfice (surfice, sorry I have gone blank on the spelling???) This was anounced by NASA. I would like to read our article on this if we have one, can some one please link to it. Also, I have ready the article on Terraforming planets, and would like to read more in this field, can you please sugest articles in this vein. What university courses could one take to help further the future science of Terraforming, to help bring about this phenomenon faster, as I would love to be the man who 500 years from now is known as the father of Terraforming, or the Father of Human Colony II Mars. Thank you. —Preceding unsigned comment added by 62.172.58.82 (talk) 10:17, 6 June 2010 (UTC)[reply]
Given a timeframe of 5-10 years to create a vehicle, what is a reasonable quote for the amount of time it would take to send a probe to another solar system, given current technological levels? Ideally, the vehicle would return information to the earth about the solar system. I am assuming that current technology levels would not be good enough to reach relativistic speeds, so the perception in difference in time between the vehicle itself and the earth would be negligible (i.e., well within the margin of error for the quote). Magog the Ogre (talk) 16:14, 6 June 2010 (UTC)[reply]
Around 60,000 years. (I figure Cassini is currently at 25km/s, and 5 light years distance, is 60,000 years.) Cassini will slow down as it gets farther from the sun, but we could make some future ship a bit faster. But realistically we couldn't do it. The problem is how to decelerate when you reach the end point. We don't even know what the solar system looks like, we'd need artificial intelligence good enough to survey planets, then pick and calculate a gravity slow down, I'm not sure we are able to do that. Ariel. (talk) 17:10, 6 June 2010 (UTC)[reply]
I expect the best method (using already existing technology) would be a kind of ion drive. The advantage of ion drives is that they can continue thrusting for a long time. If we want to launch in the next 10 years, though, it's still going to take at least hundreds of years. It would get there sooner if we waited until faster technology was invented and then launched. --Tango (talk) 20:37, 6 June 2010 (UTC)[reply]
There is no need to decelerate. It would be nice to do so, but you could still get lots of good science from a fly-by mission. I would expect our first interstellar missions to be fly-bys (just as our first interplanetary missions were). --Tango (talk) 20:37, 6 June 2010 (UTC)[reply]
I believe that if cost where not an issue, we could get a probe to the Alpha Centauri system in "just" a few hundred years. Ion thruster systems get better every year, (this report shows no hint of failure after more than 3 years at full power), and given their great mass/force ratio, they would be ideal for such a mission. Unfortunately I can't find the specs on the thrust they are capable of (which are quite small in comparison to chemical rockets), but even assuming just 10 km/s/year, (about 1/1000 the acceleration due to earth's gravity), the probe could achieve speeds more than 4 times that of the fastest current probes before it left the Solar System.-RunningOnBrains(talk)21:01, 6 June 2010 (UTC)[reply]
It would be tough to power it. Assuming you ran for about 10 years, and the ship weighed 2 tons, you would need 10x10^12 joules, or about 32kW for those 10 years. Radioisotope thermoelectric generators have energies in the tens of watts, so that will never work. You would probably need a nuclear reactor such as Safe Affordable Fission Engine. But even then it would still take 15,000 years. Ariel. (talk) 01:41, 7 June 2010 (UTC)[reply]
In fact, I believe the biggest problem with this mission would not be getting there, but relaying what the probe sees back to earth. It would be useless to send a probe there if it can't send any information back, and New Horizons, after its fly-by of Pluto, is expected to take nine months to transmit just 8 GB of data back to Earth [1]. The amount of power needed to even reach those data transfer rates from 4 light years (and near the shine of a bright star)...well, I don't even want to begin to speculate.-RunningOnBrains(talk)21:01, 6 June 2010 (UTC)[reply]
Let's speculate. New_Horizons#Telecommunications quotes 12W transmit power and 4.5 'light-hours' (signal latency). Link power is proportional to distance squared. Link power from Alpha Centauri would be 12W x sqr( 4.4 lightyears / 4.5 lighthours) = 1.1 kWCuddlyable3 (talk) 21:38, 6 June 2010 (UTC)[reply]
A year is about 8000 hours, so multiplying by the square of the ratio (year/hr) should give you something like 700 MW, not 1.1 kW. Maybe you took the square root instead of the square? --Trovatore (talk) 21:50, 6 June 2010 (UTC)[reply]
It occurs to me that one way to do better is to make the transmitting antenna bigger. With a bigger antenna you can get a more unidirectional signal — ultimately the power is still going to fall off as the square of the distance, but you can make the constant coefficient much more favorable.
How about having it shoot out some sort of very fine webbing a kilometer across, and using that as an antenna? Maybe it could even double as a light-sail. Obviously there are some practical challenges, but that's engineering's department; I'm over here in blue-sky big-picture territory. --Trovatore (talk) 22:10, 6 June 2010 (UTC)[reply]
Effectively that's like using a bigger antenna, because the important thing is the ratio of the aperture size to the wavelength (assuming spatial coherence across the entire aperture). But sure, a laser might be more practical than my idea. On the other hand it can't double as a light sail. So put together a presentation and present it at next week's meeting, please. --Trovatore (talk) 23:00, 6 June 2010 (UTC)[reply]
The Project Orion spaceship project was designed to reach 10% the speed of light, before it was scrapped. This would allow it, assuming constant maximum speed, to reach the Alpha Centauri system in 45 years. ~AH1(TCU)01:27, 7 June 2010 (UTC)[reply]
Apparently we've all forgotten that NASA is actively testing a solar sail, which can propel to relativistic speeds without needing internal power (simply getting momentum from sunlight. Of course, a solar sail ship needs a sail on the order of 1 km^2 in size and extremely lightweight, but technologically we're already capable. Oh, and if you want, it can decelerate for free as it approaches a new solar system, though relativistically that takes quite a long time in the ship's reference frame. SamuelRiv (talk) 05:35, 7 June 2010 (UTC)[reply]
Assuming you've got something wizzing very fast towards a star as described above, would it be possible to put it in orbit around that star? If it was going very fast, I imagine it would have to pass close to the star to be captured in orbit around it. Would this mean that it would be destroyed by the heat or gravity or other forces 92.24.182.231 (talk) 10:29, 7 June 2010 (UTC)[reply]
I would refer to the article on orbits. With escape-velocity speed, an object will travel around a star as a hyperbola, thus never returning. It may be that to get into elliptical orbit one has to get so close to a star as to be within the star itself, which is problematic because in doing so the star's gravitational influence on the object is reduced (see shell theorem), so the elliptical orbit is impossible anyway. But even if an elliptical orbit is established, at very high speeds the result will be a very eccentric orbit going very very far from the star and lasting perhaps thousands of years or more, as in Oort cloud objects. SamuelRiv (talk) 15:27, 7 June 2010 (UTC)[reply]
If the target solar system had some handy gas giants (which is looking like a pretty safe bet) - then you could probably do some aero-braking manouvers to bring your craft's speed down to where an orbital capture would be feasible. But the number of times you'd have to loop around to do that might be kinda large...it might take decades to get yourself into a comfortable orbit. SteveBaker (talk) 19:04, 7 June 2010 (UTC)[reply]
How can using algae to make fuel be net energy positive?
Recently on the Science Channel some people like J. Craig Venter and Ray Kurzweil were talking about the prospects for the future of genetic engineering and one of them (I forget which one) was talking about making life that would more efficiently manufacture fuels (by which I presume he meant hydrocarbons) humans could use. The problem I don't get is, if you want a bacteria to produce for you a molecule of hydrocarbon that could release X joules of energy when you use it, wouldn't you have to feed that bacteria more than X joules to make it for you? So if you have X+ joules it would be more logical to store that up than use for your energy needs. 71.161.47.112 (talk) 16:55, 6 June 2010 (UTC)[reply]
See algae fuel - algae make fuel from sunlight - but different algaes make different types of fuel: some primarily carbohydrate/cellulose, others produce a substantial amount of oil as well. I'd guess they were suggesting making new types of algae that produce more oil as a percentage, since this is a more desirable form of fuel.77.86.124.76 (talk) 17:03, 6 June 2010 (UTC)[reply]
Yeah, but we're not talking about green algae; we're talking about blue-green algae, AKA cyanobacteria. Contrary to what 77.86.124.76 says, they are bacteria. However, in accordance with what 77.86.124.76 says, they are also "a lot like plants", in the sense that they use photosynthesis. --Trovatore (talk) 19:34, 6 June 2010 (UTC)[reply]
I tried to be careful in what I said (because I'm not a biologist and likely to make obvious schoolboy errors - as I did) - but all algae? Bacteria says they are unicellular, whereas Algae says it included multicellular forms. eg Are seaweed bacteria ?? please put me out of my misery77.86.124.76 (talk) 20:04, 6 June 2010 (UTC)[reply]
No, seaweed are not bacteria. But no one is proposing to make fuel out of seaweed. Well, as far as I know, anyway.
The problem is that the word algae comprises organisms that are more different among each other than you are from an earthworm. Green algae are plants; bluegreen algae are bacteria. You can't get too much more different than that.
Now, on reviewing the algae fuel article, it does look like I spoke a little hastily in assuming that all the fuel stock was to come from bluegreen algae. Apparently the fuel makers don't really care about the biology, just about getting the reduced carbon, so very small green algae are also OK with them. --Trovatore (talk) 20:11, 6 June 2010 (UTC)[reply]
It's ok I worked it out for myself, yes they use algae, in fact the article mentions as examples algae species, though cyanobacteria are potential biofuels too. [2] Anyway didn't you get the email - we're calling them cyanobacteria now to avoid just this confusion :) 77.86.124.76 (talk) 20:25, 6 June 2010 (UTC)[reply]
People are indeed considering making fuel out of seaweed - kelp is hugely productive (we're talking higher than most land crop plants) and it wouldn't be impossible to farm using some of the techniques from seaweed farming. Regarding the use of microalgae, the research is still in early phases and at the moment the only algae that can be GMd is Chlamy which would be no use for making fuel. We're starting to get some idea of algal diversity (Venter's helped a lot by chartering a boat which analysed sea water from around the world) and this should allow us to make algae that produce fuel in the future. Producing hydrocarbons would involve the manipulation of pathways that are currently activated by algae in response to stress and instead use them constantly to either accumulate oil internally or secrete it externally. 86.7.19.159 (talk) 09:39, 8 June 2010 (UTC)[reply]
I think the replies have kind of skipped over the essence of the actual question. Just to be clear, nobody is talking about anything that's greater than 100% efficient. We're not allowed to do that. The only thing being explored is how to make something more efficient than it is now. As the first respondent mentioned, algal-based fuels are being explored because the initial energy comes from sunlight which is "free" in the sense that the energy was going to hit the earth anyway and the source (i.e. the sun) is basically inexhaustible, again in that limited sense that it will keep shining whether we harvest the energy or not. Matt Deres (talk) 18:23, 8 June 2010 (UTC)[reply]
I was under the impression that the OP already understood that, and had since it was explained in the first few replies. Their confusion I think arose from not realising we were talking about organisms that get their energy from the sun (rather then being 'feed'). They do have a follow up question about solar cells that was mostly ignored. Nil Einne (talk) 18:49, 9 June 2010 (UTC)[reply]
I reacted sodium acetate with yellow iron(III) chloride to form a blood-red solution. Is that iron(III) acetate? The article on iron(III) acetate says that it is insoluble, but in here it states that there is a coloration. My solution is soluble. Is it "nonbasic" iron(III) acetate as compared to basic iron(III) acetate, which is what the article is about? --Chemicalinterest (talk) 18:08, 6 June 2010 (UTC)[reply]
I am trying to synthesis chloroform for a chemistry project and i ran into some trouble.
the chemicals i combined were
ethanol 80 proof
calcium hypochlorate from pool tablets
and a small amount of sodium bicarbonate to take care of the formic acid that should be made.
anyways during the reaction i noticed prussa blue crystals forming at the bottom of the glass. any idea on what they could be? —Preceding unsigned comment added by 76.14.125.132 (talk) 22:02, 6 June 2010 (UTC)[reply]
I can't think of a reaction that would have made a blue colour off hand. Are you sure that the Calcium hypochlorite didn't have a blue additive in them - it seems some commercial formulations do eg [4][5]77.86.124.76 (talk) 23:52, 6 June 2010 (UTC)[reply]
Let's assume I have a great amount of wealth (10's of billions of dollars). Is there anything to stop me contracting someone to build me a moon base?
What would the estimated cost of a self sufficient base be, including any systems needed to remain healthy on the surface for an adult lifetime (for example, detrimental effects due to reduced gravity).
Finally, (this depends on the answer), is there any individual or group with the funds to actually do this?
"Self-sufficient" is probably beyond the range of current technology. To be truly self-sufficient, you'd need to be able to manufacture any spare part of any machine using only materials that can be mined from Moon rock. That's a very tall order. We might conceivably be able to extract water - and therefore oxygen and hydrogen+oxygen rocket fuel - but Moon rock points out that the only elements present in moon rock in appreciable quantities are Calcium, Aluminium, Silicon, Oxygen, Iron, Magnesium and Titanium. Without nitrogen or carbon (and a bunch of other stuff) - you are pretty fundamentally screwed when it comes to food production. You'd have to recycle every single gram of those two elements with fanatical attention to not losing anything whatever in the processing! You might manage to find deposits of carbon from meteorites that impacted the moon in the distant past - but nitrogen is harder.
As for funding, Forbes list of billionaires says that no single person could fund more than about $55 billion - and that's nowhere near enough. Constellation_Program#Cost says that the simplest manned mission would cost in the region of $200 billion. What you are proposing (a permenant self-sufficient base) would probably cost trillions. A consortium of the top 20 richest people could possibly establish a moon base - but there is no way they could keep it funded over the long term. So, I think the answer is a solid "No". SteveBaker (talk) 00:49, 7 June 2010 (UTC)[reply]
The Outer Space Treaty appears to say that you have to get permission from your government first. The Moon Treaty says you can't own private extraterrestrial property at all, but fortunately only applies if you are in a country that ratified it, e.g. Australia or Belgium. (Don't those countries have any private satellites? Hm.) I have a feeling I once read that NOAA asserted a ban on anybody building anything on the moon (can't find any reference other than my own memory of the buzzkill). I'm not sure what would come of all this official indignation if you went ahead and built a moon base anyway, mind you. Maybe they'd blockade your space ports. 213.122.43.84 (talk) 04:39, 7 June 2010 (UTC)[reply]
Practically speaking though if you had ownership of such sums with complete discretion on how to use it you might well be able to "leverage" your money by bribing politicians to do it for you provided you were a bit subtle. I don't know how much it would cost to effectively control the US government NASA budget completely by campaign contributions but if you had $1bn a year to throw around I think you could probably get huge government expenditure in support of your aims... --BozMotalk12:31, 7 June 2010 (UTC)[reply]
If I put a house on the moon, and post some No Trespassing signs, I'm going to go out on a limb and say that the property is mine. If the governments back on Earth decide not to recognize it, all the better. I'll save on taxes that way. APL (talk) 15:46, 9 June 2010 (UTC)[reply]
