John Cuthber

Something thinks it is me. I choose to define myself as whatever is having that thought or,if that thing doesn't exist then I choose to define myself as that abstract thought. Whichever of those two definitions I choose for "me", I exist. It may not be much of an existence, but I can be sure it is real.

"Could you use reflectors, anchored to the moon, for long-base-line Gravity Wave detectors?" Yes, but where would you put the other end of the base line? Earth's atmosphere pretty much rules it out. So you would need a satellite in orbit round the moon to use as the "other end" You could do that, but the earth's gravitational field would make it difficult. It's probably best to do what they already chose to do.

It is obviously possible to do major surgery without anaesthetics. Before they had anaesthetics that was the only option. It was not considered a good thing and the pain killers were hailed as a great improvement.

The changing electrical and magnetic fields would act as a radio transmitter. It would lose energy that way (if no other).

Having just had a drink I'm going to put down my glass of water. I could put it at the left hand end of the table. I could put it at the right hand end. I could put it half way, or a quarter of the way or an eighth.... I have an infinite number of choices (give or take the Planck Length).

And...?

In principle, if you dissolve the mixed metals in excess hydrochloric acid and add hydrogen peroxide to oxidise the iron to ferric chloride, then extract the solution with ether (which will remove the iron as "HFeCl4"). Then add a solution of sodium hydroxide and hydrogen peroxide slowly. The peroxide will oxidise the Ce(III) to Ce(IV) and the sodium hydroxide will ppt the Ce(Iv) as CeO2. H2O Until all the Ce has been precipitated, practically all the other lanthanides will stay in solution. It's messy, but you should, with care and practice, be able to get a fairly pure sample of CeO2. H2O that way. You can then add more sodium hydroxide solution and precipitate the other lanthanides. Adding oil will just add fuel to the fire. I don't think you can melt these metals in air. They might not actually catch fire, but the oxidation will make it impractical.

Could you two stop the ad hom attacks please. I rather suspect that what you have is a communication problem. While CCl4 is not polar overall, it has a lot of very polar bonds so it will dissolve polar things quite well. My best guess is that when you say "In CCl4 you form a ionic compound which leaves the system...simple. " you mean that the reaction of the brominating agent and /or the by product (HBr) with the pyridine gives a pyridinium salt which is insoluble. I don't think there's any suggestion of a reaction with CCl4 so this bit " The only way I can see your suggestion working is if the chlorine attacked the pyridine N to give a salt, which doesn't really make sense since the nitrogen is (as you pointed out) basic and reactive towards Lewis acids rather than Lewis bases." is, as far as I can tell, a misunderstanding.

The major problem is that it won't work. For a start the magnet it mentions will lose its magnetism when heated. Also, it won't work through a steel crucible. But that's not the real problem. Imagine I'm living in Siberia. It's 40 below zero here. I have a mixture of two solids; ice and a little salt (say about 20%) salt. I look up the melting points and find that one melts at 0 C and the other melts at 800 C So, I figure, if I warm the mixture to a temperature between those two values, the ice will melt and the salt won't, so I can filter off the salt and separate them. I'm going to be disappointed when I see that , at -10 or so, the whole lot has melted and the salt has dissolved in the water. The same problem will happen with the mischmetal. The Pr and La will dissolve in the Ce. Also, the mixture will react rather quickly with air. They don't use this stuff for lighter flints for a joke; it's easy to set on fire. Separating the lanthanides isn't easy. It's one of the more difficult challenges in preparative chemistry. If you could do it with a thermometer and a furnace they wouldn't resort to ion exchange chromatography when they did it commercially. It is possible to get a fairly clean sample of cerium oxide from the lighter flints (and a mixture of the other lanthanides) if that's what you want for an element collection.

According to this http://www.niceskating.com/FAQ.html you need roughly a hundred times more power than you have available. "What is the power and water consumption of an ice rink? The power consumption is related to the cooling capacity required by the fridge unit to maintain the rink as frozen ice. The power of these machines chillers, typically range from 200 kW to 1,500 kW or more. " Unless, of course, you are setting up a rink in Canada in Winter or something.

And the speed of light doesn't. So you are still wrong.

From Wiki "The best current (2009) estimate of the International Astronomical Union (IAU) for the value of the astronomical unit in meters is A = 149 597 870 700(3) m," From Robert's paper "By selecting an average A.U. of 1.495417807 X 10^13cm , one which is just 375 millionths less than the established value," So, it's wrong. That's it. End of "theory". Robert, for the record, numbers like that are often quoted with an error margin. Sometimes it's clearly specified, sometimes not. In this particular instance the 3 in brackets after the number is the error margin. The right answer is known to more than 9 digits and your answer only agrees to 4 digits. So you have got an answer that's laughably wrong. Pretending that they are the same number means it's not science and it might as well be numerology.

I have a suggestion: give up. If they are fairly athletic and prepared to work hard you can probably get something like 100 Watts from a person. So you have a budget of about 2Kw. It will take more than that to keep the ice cold. Also, the whole point of skating is that it's a low friction surface. If you draw energy from the motion of the skaters they will feel like they are "skating" on sandpaper.

I know that Ethalpy said this, but I'm repeating it. Dry sand can be used as a mould for any of those metals. Slightly dap sand can be used to spray molten metal about the place and give you a nasty, or even fatal set of burns.

I know plenty of people who eat apple seeds. As long as you don't chew them they don't release any cyanide and, in due course they make their way out. Not much use to the apple tree when the seeds get flushed, but other animals eat apples too and they would do a fine job of spreading (and fertilising) the seeds.

Given our inability to produce vitamin C it seems that plants have influenced us in much the same way that we have influenced them.

0.04 is 40/10 times 0.01

It rather depends on the (admittedly loose) definition of plants. The cyanobacteria were, for starters, starters. They were among the earliest organisms and predate the algae and the plants. However what I actually said was that by the time plants (specifically the ones we see like grass and trees and such) evolved, there were already a lot of algae. There could have been herds of unicorns before them, but it doesn't detract from what I said. from wiki "Probably an algal scum formed on land 1,200 million years ago. In the Ordovician period, around 450 million years ago, the first land plants appeared.[1] " There were, according to the fossil record, red algae 1200 million years ago. The green plants are about half as old. in any event, it's a better answer than "they are green because they absorb red light".

Among the strange things I have done for a living is analyse for explosives residues (and decomposition products). I didn't just look for nitrate esters and I don't think the investigators of the 9/11 event would have done so. There's no evidence of explosives (of any sort) having been used. Perhaps the most critical evidence here is that there is no explosion on the videos. Thermite wouldn't work. If it did hen the professionals would use it. it seems reasonable to me that, in the absence of any other cause, you have to accept that the towers came down because some bastards crashed two planes into them. Of course, since that doesn't involve blaming the government (at least directly) some people won't accept it. This sort of thread should be moved to the "psychology" sub forum so we can discuss the reasons for their delusions.

Just a quick thought about the importance of group theory in spectroscopy. The groups concerned are the symmetries of the molecules and they "predict" the transitions between energy states that are permitted. According to the maths, hydrated copper sulphate isn't blue; Cobalt chloride is white and certainly doesn't change colour from blue to pink in response to humidity changes; and rubies are colourless. It's fair to say there's more to it than group theory.

Most plants that we see are green because the red algae got there first. With them absorbing the green light there was only one way to compete- use a different colour of light. What's truly astounding is that it took 31 posting of bickering and insults before someone cited another site which actually answered the question.

" I have no idea how to translate this into its actual size when the scale is bigger than the apparent size of the image" What would you do if it was smaller?

I predict an outbreak of numerology.

Incidentally, when people who know what they are doing; have all the time they need; and proper access, want to demolish a building, they don't use thermite. They use explosives; in particular, shaped charges. So why do the conspiracy nutters insist on it? And I'm still wondering how that "thermite" which ignites at 430C survived the fire.

Or you could just sieve out the nitrogen. http://en.wikipedia.org/wiki/Nitrogen_generator#Membrane_technology It would be slightly better still if you separated the O2 from the N2 before the combustion process. The flame would be hotter and so more of the energy could be recovered. However, it would be very expensive. You also need to remember that carbon capture doesn't stop us running out of coal, oil or gas so it's not a sustainable technology. In any event, I don't think your system would work, it reminds me of this " Big whorls have little whorls That feed on their velocity, And little whorls have lesser whorls And so on to viscosity."