francium

Francium, the fabled element at the bottom of group 1 and the most reactive of the alkali metals (if you are not familiar with the reactivity of group 1 metals, have a look at the video elsewhere on this site).

However, the truth is a little more boring. Francium is vanishingly rare and is found only as very small traces in some uranium minerals. It is the most unstable of the 92 naturally occurring elements and as it is so radioactive that any amount formed would quickly decompose into other elements. Although there are about 20 known isotopes of the metal only Fr-223, with a half life of 22 minutes, occurs in nature. There is estimated to be only ever about 20-30 g of the element present in the earth's crust at any one time and no weighable quantity of the element has ever been prepared or isolated.

Bad news for those of us hoping to see what happens when you put it into a basin of water.

Francium was discovered by Marguerite Perey, who worked as an assistant to Marie Curie, in France (from which the element takes its name) in 1939.

an inconvenient truth

Some of you may have seen 'An Inconvenient Truth' and be aware of Al Gore's involvement as an alarmist in the global warming argument. However, as good scientists we should always try to have a balanced view based on the provable facts available, and whenever possible arrive at this view independently of politics.

To see how much you really know about global warming take this quick test.

global warming test

If this has opened your eyes a bit and you want to find out more, have a look at this site.

icecap

methane bubbles

If methane gas is forced through a mixture of water, glycerol and washing up liquid, some rather flammable bubbles can be produced. Anyone got a match?

rocket trolley

New and improved, this time using a low friction trolley.

quantum santa

OK, so the last post wasn't good news for us believers, but what if Father Christmas was a macroscopic quantum object?

In his book, Unweaving The Rainbow, Richard Dawkins boasts that he tried to tell a six year old child that Father Christmas didn't exist. His argument was that Father Christmas would not be able to climb down all those chimneys and tiptoe noiselessly to the bedsides of hundreds of millions of children, all in one night. There simply wouldn't be enough time, even if reindeer were hypersonic.

Well, apart from being a somewhat cruel thing to do to a small child (the distinguished professor for the public understanding of science should pick on someone his own size), the argument is, to be charitable, an incomplete explanation. Dawkins may be no slouch when it comes to evolution, but he knows (by his own admission) rather less about physics.

Of course Father Christmas exists, and he can visit arbitrarily as many children has he pleases in as short a time as is convenient, barring mid-air reindeer pile-ups. The reason is that Father Christmas is a Macroscopic Quantum Object.

Let me explain. It is a feature of the quantum world that particles - such as electrons - can be in more than one place at a time, provided that nobody is watching. In a famous experiment known as the "two-slit" test, physicists have been able to fire a single particle at an opaque plate with two separate slits in it. The diffraction pattern seen on the other side of the slits suggests that the particle passes through both holes at once and interacts with itself. However, if detectors are placed at the slits, to see which slit the particle passes through, the diffraction pattern disappears, and the particle can be seen to pass through either one slit or the other, but not both. The key lies in the fact of observation. Provided that nobody seeks to measure the effect with more than a certain amount of precision, the particle keeps all its options open. But if someone looks too closely, the particle makes its choice. In the language of physics, its quantum wavefunction collapses.

Now, let's think of Father Christmas as a particle, obeying the rules of the quantum world. Following the logic of the two-slit experiment, it is perfectly possible for him to visit all the good children of the world simultaneously, provided that he does so unseen. If he is spotted, his wavefunction will collapse and he will be revealed as your Dad with a comedy beard after all. The quantum nature of Father Christmas explains the taboo against seeing him do his job - which Dawkins does not explain.

But there's more. It is possible to object that Father Christmas is far too large, rubicund and jolly to be a particle. In the real-life, macroscopic world of people, elves and flying reindeer, the quantum behavior of each of the squillions of particles from which we are made averages out, so what we see is the everyday phenomenon of causes preceding effects, and people who can never be in two places at once.

Cynics might attribute this last consequence to the deficiencies of Railtrack, but it is a fact that real people, even bearded men with red hats and big boots, tend to be found in discrete locations, irrespective of whether they are being watched or not.

This objection doesn't wash, however, because it is possible to have macroscopic quantum objects that are larger than single particles. Scientists have managed to choreograph large clusters of atoms to behave as if they were just one particle, in a kind of nanoscopic Busby Berkeley routine. Admittedly, these clusters are too small to see with the naked eye, let alone qualify as cheerful red-faced men with sacks full of gifts, but the point is made. Importantly, these macroscopic quantum objects observe the rules of the quantum world when cooled to within a whisker of absolute zero - minus 273 C. Any warmer than this, and the choreography breaks down and the clusters behave like any old bunch of atoms.

Nevertheless, in this frigidity might lie an explanation for another feature of Father Christmas that Dawkins neglects to explain - the undeniable fact that Father Christmas traditionally inhabits cold places, such as Lapland or the North Pole. OK, so neither of these places gets as chilly as absolute zero, but it must count for something that no deserving child would address their wish list to hot places such as, say, Borneo or Brazil. The very idea is quite ridiculous. QED (which stands for Quantum Electrodynamics, obviously)

the physics of santa

We all still believe in Father Christmas don't we? With Christmas fast approaching, time to take a closer look at the work of the big man, just to see if it really is possible that he might actually exist.

1. There are approximately 2.5 BILLION children (persons under 18) in the world. This is based on the World Population Consensus of 2000 and using the US's basis of 42% population under 18. However, since Santa does not visit children of Muslim, Hindu, Jewish, or Buddhist religions, this reduces the workload for Christmas night to 33% of the total, 825 MILLION (according to the World Population Reference Bureau). At an average rate of 2.5 children per household worldwide, that comes to 330 MILLION homes, presuming, of course, that there is at least ONE good child in each household, not a real safe assumption, but...

2. Santa has a total of 31 hours to work with, thanks to the different time zones and the rotational speed of the earth, assuming he travels from East to West, a safe assumption. This works out to about 3000 visits per second. This is to say that for each Christian home with a good child, Santa has just under 1/3000th of a second to park the sleigh, hop out, jump down the chimney or mist through a door or window, fill the stockings, distribute gifts around the tree, eat whatever snacks the good children have left him, get back up the chimney or back out the door, jump into the sleigh and get on to the next house. Assuming each of these 330 MILLION stops is evenly distributed around the landmass of the world (which we know is false, but accept to make the calculations simpler), we are now looking at about 0.78 miles per household; a total trip of 258 MILLION MILES, not counting bathroom breaks and watering the reindeer stops. This means that Santa's sleigh MUST move at about 8.3 MILLION MPH or 2,300 miles per SECOND – 3000 times the speed of sound. For purposes of comparison, the fastest manmade vehicle, Voyager II, moves at a pokey 39 miles per second, and a conventional reindeer can run at best 15 miles an HOUR.

3. The payload of the sleigh adds another interesting element. Assuming that each child gets nothing more than a medium sized Transformer© set of about 2 pounds and a small Sponge Bob SquarepantsTM hand puppet, the sleigh is carrying over 825 THOUSAND TONS, not counting the fat man himself. On land, a conventional reindeer can pull only 300 pounds. Even granting that these special reindeer could pull 100 times the normal amount, the job would take 36,000 reindeer. This, of course, increases the payload, not counting the fat man, another 54,000 tons, or roughly 7 times the weight of the QEII, the largest cruise ship on earth.

4. 880,000 TONS traveling at 2,300 MILES PER SECOND creates an enormous air resistance – this would heat up the reindeer in the same fashion as a shuttle re-entering the atmosphere. The lead pair of reindeer would absorb 32 QUINTILLION (32,000,000,000,000,000,000) Joules of heat energy every second each. This is 6.4 x 1019 WATTS of power – enough to light up the United States for 55 MILLENIUM. In short, they would burst into flames and vaporize into plasma, the 4th State of Matter, instantaneously, exposing the reindeer behind them and creating a deafening sonic boom in their wake which would pulverize the remaining reindeer if they would, indeed, still be there. The entire reindeer team would be vaporized within 0.000 426 seconds, or right about the time Santa reaches the 2nd house of the trip. Not that this matters however, since Santa as a result of the tremendous acceleration from rest to 2,300 MILES PER SECOND in 1/3000th of a second would subject him to a force = 1.1 BILLION times the pull of gravity here on earth. A 250 pound Santa, a conservative estimate, would be pinned to the back of the sleigh by 275,000,000,000 POUNDS of force, instantly crushing his bones and organs and reducing him to a quivering blob of pink goo.

5. Therefore, if Santa ever existed, he doesn't now.

6. But, we all know that Santa DOES EXIST and survives very well, thank you, due to his special powers inherited from his home planet of Krypton.