I went for a walk today, from DESY through the pretty suburb of Othmarschen, down to the River Elbe, then along the beach to the Museumshafen (literally a harbour museum, this is where several old ships are maintained). Everything is beautiful, green, clean, safe, and friendly, for this is one of the richest suburbs of one of the richest towns in the world. Everything was just like it was the last time I was here, and it will stay this way for a while, too, as it is pretty much perfect the way it is.
I don't know whether it's just the monotonous perfection, or the fact that every cafe and restaurant reminds me of someone I once loved, or the fact that I'm on shift, sat 20m underground doing fuck-all, but I'm feeling down. I wish I was excited by being in a big city, but I've seen all I want to see of Hamburg, and I want to go home.
Sunday, August 13, 2006
Saturday, August 12, 2006
Hamburg again
The least said about Hamburg and Hermes the better. It's depressing me too much, and I want out of here.
I'm surfing the internet quite a lot at the moment, and am desperate enough to read the reports of english county cricket matches. The bitterest rivalry in county cricket is Yorkshire vs. Lancashire. It all goes back to the wars of the roses, and neither team likes to lose this match.
Often, if a match is heading for a certain draw because there won't be enough time for all the innings to be completed, a captain in a commanding situation will make a "sporting declaration". This means that he forfeits some of his batters to speed up the game, losing potential runs in the process. The upside is that there is then more time to bowl out the other side and win the match, the downside is that the other team could win. In any case the spectators will be entertained, and a win would be worth many more points than a draw.
A defeat by your bitterest rivals is unacceptable, though, so Yorkshire decided to carry on batting through the last day to secure a safe draw. For the last few hours of the match there was no possibility of victory. Blah blah blah, you say. Well all this is leading to a lovely quote from the match report on the bbc website.
I'm surfing the internet quite a lot at the moment, and am desperate enough to read the reports of english county cricket matches. The bitterest rivalry in county cricket is Yorkshire vs. Lancashire. It all goes back to the wars of the roses, and neither team likes to lose this match.
Often, if a match is heading for a certain draw because there won't be enough time for all the innings to be completed, a captain in a commanding situation will make a "sporting declaration". This means that he forfeits some of his batters to speed up the game, losing potential runs in the process. The upside is that there is then more time to bowl out the other side and win the match, the downside is that the other team could win. In any case the spectators will be entertained, and a win would be worth many more points than a draw.
A defeat by your bitterest rivals is unacceptable, though, so Yorkshire decided to carry on batting through the last day to secure a safe draw. For the last few hours of the match there was no possibility of victory. Blah blah blah, you say. Well all this is leading to a lovely quote from the match report on the bbc website.
Such was the dull nature of the game in the closing stages, Lancashire's Mal Loye fielded wearing a trilby hat.
Thursday, August 03, 2006
Dimensional Analysis
The thing that most fascinated me about physics is that the dimensions work. If, for example, you multiply mass by a velocity squared then you always get an energy. People knew this long before Einstein came along with his E=mc^2, a revolutionary equation which changed the world but completely obeys the laws of dimensions. Had he claimed that E=mc he would have been laughed out. Physicists are prepared, eventually, given enough evidence, to believe that even the most boring lump of rock could explode with an energy that would put dynamite to shame, but they won't let you fuck around with dimensions.
Biologists, on the other hand, will quite happily fuck around with dimensions. Ever wondered what the surface area of a human body is? Probably not, unless you're into body painting (tell me darling, do you think 20 litres will be enough for your whole backside?) or are looking for an animal-skin rug with a difference.
Well wonder no more, because it's easy to find out. Just take your mass (m) in kilograms, and height (h) in centimetres. Then pick an equation from the ones below to find your surface area in square metres:
Gehan and George A = m^0.51456 * h^0.42246 * 0.02350
Mosteller A = m^0.5 * h^0.5 / 60.
Haycock A = m^0.5378 * h^0.3964 * 0.024265
Du Bois and Du Bois A = m^0.425 * h^0.725 * 0.007184
The ^ sign means "raised to the power of". My body surface area is therefore between 2.06 and 2.1 square metres, depending on which equation I choose.
How did anyone come up with these equations, and what does this have to do with dimensions, you ask? The first people to develop such an equation were D. Dubois and E.F Dubois in 1916. As far as I can tell they took their subjects and covered them completely in Post-it notes of known area. They then counted up the notes, and had their measurement. Only 9 people were measured before the glue (presumably) went all funny.
The Dubois' were certainly rather good at dimensional analysis, for if you take their exponent for mass and multiply it by three, and add the exponent of height you get exactly 2.
3*0.425 + 0.725 = 2.
It is possible to show that this sum will always be 2 if the dimensions of the equation are to be correct. If the result is anything other than 2, you will have calculated an "Area" in metres, or cubic metres, or "metres to the 2.01", rather than in square metres, so the Dubois' had given the calculations a good start.
There are two problems with Dubois' equation, however. The first is that it systematically overestimates the surface area, the second is that it requires competent use of a scientific calculator with a "power of" button. Gehan and George got round the first one by measuring a few more people and choosing more accurate exponents. Their equation sadly doesn't result in square metres
3*0.51456 + 0.42246 = 1.966
but it seems to work quite well nonetheless, provided you have a nifty calculator. Hancock did something similar with a similar disregard for the correct units for an area. So there were now several equations which worked but which were vastly more radical than anything ever proposed by Einstein.
But all was not lost! A simplified version of the Gehan-George equation was provided by Mosteller, who presumably had a calculator with only a square root button (remember that raising to a power of 0.5 is the same as taking the square root). Either by chance or by design he got the dimensions right, too, for three lots of 0.5 plus another 0.5 gives exactly 2.
Another nice thing about the powers of 0.5 is that this is exactly what you would get for a thin cylinder, and any mathematican could tell you that people are, to all intents and purposes, cylindrical. A mathematician could have saved 80 years of plastering people in Post-it notes by pointing out that it was obvious the powers should be both 0.5, and measuring one person to find the necessary factor of 1/60.
It seems that the Mosteller equation is slowly being accepted, so the next time you want to know your surface area just take the square root of your height, multiply with the square root of your weight and divide by 60. Go on, do it!
Some links
Source for the equations
History of the equations
A calculator for body surface area
Biologists, on the other hand, will quite happily fuck around with dimensions. Ever wondered what the surface area of a human body is? Probably not, unless you're into body painting (tell me darling, do you think 20 litres will be enough for your whole backside?) or are looking for an animal-skin rug with a difference.
Well wonder no more, because it's easy to find out. Just take your mass (m) in kilograms, and height (h) in centimetres. Then pick an equation from the ones below to find your surface area in square metres:
Gehan and George A = m^0.51456 * h^0.42246 * 0.02350
Mosteller A = m^0.5 * h^0.5 / 60.
Haycock A = m^0.5378 * h^0.3964 * 0.024265
Du Bois and Du Bois A = m^0.425 * h^0.725 * 0.007184
The ^ sign means "raised to the power of". My body surface area is therefore between 2.06 and 2.1 square metres, depending on which equation I choose.
How did anyone come up with these equations, and what does this have to do with dimensions, you ask? The first people to develop such an equation were D. Dubois and E.F Dubois in 1916. As far as I can tell they took their subjects and covered them completely in Post-it notes of known area. They then counted up the notes, and had their measurement. Only 9 people were measured before the glue (presumably) went all funny.
The Dubois' were certainly rather good at dimensional analysis, for if you take their exponent for mass and multiply it by three, and add the exponent of height you get exactly 2.
3*0.425 + 0.725 = 2.
It is possible to show that this sum will always be 2 if the dimensions of the equation are to be correct. If the result is anything other than 2, you will have calculated an "Area" in metres, or cubic metres, or "metres to the 2.01", rather than in square metres, so the Dubois' had given the calculations a good start.
There are two problems with Dubois' equation, however. The first is that it systematically overestimates the surface area, the second is that it requires competent use of a scientific calculator with a "power of" button. Gehan and George got round the first one by measuring a few more people and choosing more accurate exponents. Their equation sadly doesn't result in square metres
3*0.51456 + 0.42246 = 1.966
but it seems to work quite well nonetheless, provided you have a nifty calculator. Hancock did something similar with a similar disregard for the correct units for an area. So there were now several equations which worked but which were vastly more radical than anything ever proposed by Einstein.
But all was not lost! A simplified version of the Gehan-George equation was provided by Mosteller, who presumably had a calculator with only a square root button (remember that raising to a power of 0.5 is the same as taking the square root). Either by chance or by design he got the dimensions right, too, for three lots of 0.5 plus another 0.5 gives exactly 2.
Another nice thing about the powers of 0.5 is that this is exactly what you would get for a thin cylinder, and any mathematican could tell you that people are, to all intents and purposes, cylindrical. A mathematician could have saved 80 years of plastering people in Post-it notes by pointing out that it was obvious the powers should be both 0.5, and measuring one person to find the necessary factor of 1/60.
It seems that the Mosteller equation is slowly being accepted, so the next time you want to know your surface area just take the square root of your height, multiply with the square root of your weight and divide by 60. Go on, do it!
Some links
Source for the equations
History of the equations
A calculator for body surface area
Wednesday, August 02, 2006
Food!
Today I ate the following:
Breakfast: Boiled egg and toast, porridge and a peach.
Morning snack: 1 apple
Lunch: Soup, 2 sausages, mashed potatoes, pasta salad, green salad.
Afternoon coffee: 2 Muffins, 1 apple, 1 ice cream.
Dinner: Plate of pasta salad, 1 yoghurt, 1 apple
Supper: Plate of chips
Midnight snack: 1 Muffin with a mug of cocoa.
I don't know how many calories this is, but it seems to be quite a lot to me. The funny thing is that if you remove the chocolate muffins, ice cream and chips you get a nice healthy diet. Ever since cycling to the Dillberg on Sunday I have been eating as much as possible. I'm tired, and seem to be using most of my energy to digest food. I suppose that I should just count myself lucky to be hungry, thin and well-off in a country where food is plentiful.
Breakfast: Boiled egg and toast, porridge and a peach.
Morning snack: 1 apple
Lunch: Soup, 2 sausages, mashed potatoes, pasta salad, green salad.
Afternoon coffee: 2 Muffins, 1 apple, 1 ice cream.
Dinner: Plate of pasta salad, 1 yoghurt, 1 apple
Supper: Plate of chips
Midnight snack: 1 Muffin with a mug of cocoa.
I don't know how many calories this is, but it seems to be quite a lot to me. The funny thing is that if you remove the chocolate muffins, ice cream and chips you get a nice healthy diet. Ever since cycling to the Dillberg on Sunday I have been eating as much as possible. I'm tired, and seem to be using most of my energy to digest food. I suppose that I should just count myself lucky to be hungry, thin and well-off in a country where food is plentiful.
Tuesday, August 01, 2006
Rain Stopped Play
A cricket match at the highest level has five days to be completed, with roughly six hours per day. If it rains or it is too dark then play is suspended, and the time is usually lost. Should the match be incomplete after five days then a draw is declared. It is therefore possible to draw a match simply by having bad weather. Take for example the first test of the ashes series of 1926, played at Trent Bridge in Nottingham. After less than an hours play it started raining, and kept on raining. Play was never restarted and the match was drawn. Only two of the England team even got onto the pitch, the rest stayed in the Pavilion and presumably drank a lot of tea. Fortunately there were four more matches in the series, which England won 1-0.
The Pakistan team of 1998 were unluckier. Trailing 1-0 after the first two matches of their series against Zimbabwe they must have fancied their chances of winning the last match in Faisalabad to draw the series. Unfortunately the match was abandoned due to four days of fog.
Our local cricket match yesterday suffered a similar fate. A pitch inspection revealed that it was raining, and so we moved directly to the beer garden. By the time the rain had stopped the light was too poor, and play was abandoned.
Here is a link which can be saved for a rainy day: a list of strange weather events which have occurred during cricket matches, which goes to confirm a quote by Benny Green, which roughly went as follows
The world is divided into two groups of people: those who think that nothing ever happens during a cricket match, and those who know that anything that could possibly happen already has.
Monday, July 31, 2006
Ignorance is Bliss
If you were forced to pick a spot for a picnic, you would do very well to beat the west shore of the "Happurger See", a reservoir near Hersbruck, which is about 25 miles south east of Erlangen. This is where I stopped for lunch yesterday as I cycled off for a rather lovely barbeque on the Dillberg with Chris.
If you sit on the shore of the Happurger See, you can look across to the "Houbirg", which is a big hill, or even a proper mountain: over 600m above sea level and with most daunting looking slopes, with rocks and small cliffs (see photo). Having a good map, but not a good dictionary, I knew that there was a "late-celtic oppidum" on the top of the Houbirg, but was left wondering how the celts had managed to get an indian takeaway, and how it had kept so well. Having eaten my picnic (a ham, lettuce and tomato sandwich plus a banana, as you ask), I skipped a few stones across the lake, and went for a quick swim too. I then set off, somewhat refreshed, for the rest of my tour.
After an annoyingly short amount of time to digest lunch I came to the first hill, as the road rose up to the village of Schupf. The hill is not too steep, but relentless, straight and with little shadow at lunchtime. I was hot and out of breath at the top of the hill, and cycled straight past a memorial to the victims of the Holocaust. I couldn't work out what the Holocaust had to do with this beautiful corner of Bavaria. Maybe, I thought, a local Jewish family had been killed. If I'd taken time to stop and look, I would have seen this memorial.
The reason for the memorial is brutally simple. Towards the end of the war the Allied bombing of German towns and factories was affecting the war effort, and efforts were made to move production underground. Some bright-headed soul must have remembered the steep-sided mountain near Hersbruck, and suggested digging out the mountain to create a bomb-proof factory. A concentration camp was then built in Hersbruck to supply labour, and the Houbirg was duly dug out. Those who died were burnt in a crematorium that now lies (presumably destroyed) in the lake. When the crematoriam capacity was exceeded they took the rest of the bodies up the hill to Schupf and burnt them in the woods.
Links:
The society for the concentration camp in Hersbruck (in German). This is an excellent website describing what happened, well written, and without waffle. It is also a very good balance to the half-facts and flippancy you get on my blog.
Wikipedia page about Hersbruck.
Wikipedia page explaining what an Oppidum is.
If you sit on the shore of the Happurger See, you can look across to the "Houbirg", which is a big hill, or even a proper mountain: over 600m above sea level and with most daunting looking slopes, with rocks and small cliffs (see photo). Having a good map, but not a good dictionary, I knew that there was a "late-celtic oppidum" on the top of the Houbirg, but was left wondering how the celts had managed to get an indian takeaway, and how it had kept so well. Having eaten my picnic (a ham, lettuce and tomato sandwich plus a banana, as you ask), I skipped a few stones across the lake, and went for a quick swim too. I then set off, somewhat refreshed, for the rest of my tour.
After an annoyingly short amount of time to digest lunch I came to the first hill, as the road rose up to the village of Schupf. The hill is not too steep, but relentless, straight and with little shadow at lunchtime. I was hot and out of breath at the top of the hill, and cycled straight past a memorial to the victims of the Holocaust. I couldn't work out what the Holocaust had to do with this beautiful corner of Bavaria. Maybe, I thought, a local Jewish family had been killed. If I'd taken time to stop and look, I would have seen this memorial.
The reason for the memorial is brutally simple. Towards the end of the war the Allied bombing of German towns and factories was affecting the war effort, and efforts were made to move production underground. Some bright-headed soul must have remembered the steep-sided mountain near Hersbruck, and suggested digging out the mountain to create a bomb-proof factory. A concentration camp was then built in Hersbruck to supply labour, and the Houbirg was duly dug out. Those who died were burnt in a crematorium that now lies (presumably destroyed) in the lake. When the crematoriam capacity was exceeded they took the rest of the bodies up the hill to Schupf and burnt them in the woods.
Links:
The society for the concentration camp in Hersbruck (in German). This is an excellent website describing what happened, well written, and without waffle. It is also a very good balance to the half-facts and flippancy you get on my blog.
Wikipedia page about Hersbruck.
Wikipedia page explaining what an Oppidum is.
Wednesday, July 26, 2006
The world's worst chat-up line.
...is probably the following
A series of tests with my flatmate have shown that it is possible to approach somebody to within 30cm (about a foot) eye-to-eye separation before they get really freaked out. Taking this as a standard distance for talking to somebody in a disco, it is possible to calculate the relation between the angle A and the height difference of two people stood a distance d apart.
By plotting the angle A as a function of height difference you can see that once the height difference reaches a certain value any further increase makes little difference to the angle. I am 1.93m, but anybody less than 1.63m will not really be able to judge how tall I am. In the same manner I can hardly tell the difference between somebody 1.55m and 1.60m: they are small.
When I started writing this post I seem to think that I had a good reason for doing so, but I have now forgotten it. The only conclusion I can find from reading this is that I need to get out more.
You appear to be rather small, but when I look into your eyes the angle from the horizontal is only weakly dependent on our relative heights.
A series of tests with my flatmate have shown that it is possible to approach somebody to within 30cm (about a foot) eye-to-eye separation before they get really freaked out. Taking this as a standard distance for talking to somebody in a disco, it is possible to calculate the relation between the angle A and the height difference of two people stood a distance d apart.
By plotting the angle A as a function of height difference you can see that once the height difference reaches a certain value any further increase makes little difference to the angle. I am 1.93m, but anybody less than 1.63m will not really be able to judge how tall I am. In the same manner I can hardly tell the difference between somebody 1.55m and 1.60m: they are small.
When I started writing this post I seem to think that I had a good reason for doing so, but I have now forgotten it. The only conclusion I can find from reading this is that I need to get out more.
Tuesday, July 25, 2006
Quick Lemon Cheesecake (second iteration)
This one was much better than the first one. The really good thing is that the recipe now has completely untransferable units. How much does a packet of Leibniz biscuits weigh? Don't ask me. How large is a tub of whipping cream, or a tube of Milchmaedchen condensed milk? No idea. Thus lives on the spirit of the recipe from my mum that required "one tin of condensed milk". In England tins of condensed milk only came in one size, and were all made by the same company (Carnation). In Germany Leibniz biscuits are a standard which can be reproduced by walking into your nearest shop, which is guaranteed to have a biscuit selection consisting of pretty much nothing else: Leibniz, Leibniz with chocolate, wholemeal Leibniz, own-brand Leibniz, own-brand Leibniz with chocolate etc
So here is the "Schnell schnell schnell lemon cheesecake".
Ingredients
For the base: 1 packet of "Vollkorn Leibniz" biscuits.
100g butter.
Brown sugar.
For the topping: 2 tubes of "Milchmaedchen" sweetened condensed milk.
2 tubs of whipping cream.
Juice of 4 lemons.
Some kind of fruit.
Instructions
Crush the biscuits, work in the butter and add brown sugar until it tastes sweet enough. Tip it into a container and squash it down. Mix the cream, condensed milk and lemon juice together, and tip onto the base. Cool for 2 hours, then put the fruit on the top and serve.
So here is the "Schnell schnell schnell lemon cheesecake".
Ingredients
For the base: 1 packet of "Vollkorn Leibniz" biscuits.
100g butter.
Brown sugar.
For the topping: 2 tubes of "Milchmaedchen" sweetened condensed milk.
2 tubs of whipping cream.
Juice of 4 lemons.
Some kind of fruit.
Instructions
Crush the biscuits, work in the butter and add brown sugar until it tastes sweet enough. Tip it into a container and squash it down. Mix the cream, condensed milk and lemon juice together, and tip onto the base. Cool for 2 hours, then put the fruit on the top and serve.
Friday, July 21, 2006
Psychosomatic stomach pains
Yesterday I had some slight stomach pains. This is the third time within a month, which is kind of worrying. Whenever this happens I don't know what the best course of action is.
Choice 1: Assume that the pain is real, and caused by an external influence (bad food, a virus or whatever). Remedy: get some rest, drink peppermint tea and eat mashed potatoes.
Choice 2: Assume that the pain is real, but caused by myself (maybe something stress related). Remedy: chill out, think happy thoughts, drink peppermint tea and eat mashed potatoes.
Choice 3: Assume that the pain is imaginary and caused by myself. Remedy: Ignore the stomach problems, eat something nice and healthy, drink a beer, and try to think happy thoughts.
I'm pretty sure that yesterday the pains were somehow self-inflicted. I went for mashed potatoes last night, which didn't help too much. Today I went for steak, bread and salad washed down with a beer and am feeling better. I think it all rests and falls on the happy thoughts. It's much easier to think of good stuff when you're eating a steak.
The trouble is that once in a while I will go for steak and happy thoughts when I really am ill, which is no good at all. If there is something really wrong then eating steak will just make you worse, which is an unhappy thought, which is a bad thing to end a post on. I therefore leave you with the words of Oscar Hammerstein.
Choice 1: Assume that the pain is real, and caused by an external influence (bad food, a virus or whatever). Remedy: get some rest, drink peppermint tea and eat mashed potatoes.
Choice 2: Assume that the pain is real, but caused by myself (maybe something stress related). Remedy: chill out, think happy thoughts, drink peppermint tea and eat mashed potatoes.
Choice 3: Assume that the pain is imaginary and caused by myself. Remedy: Ignore the stomach problems, eat something nice and healthy, drink a beer, and try to think happy thoughts.
I'm pretty sure that yesterday the pains were somehow self-inflicted. I went for mashed potatoes last night, which didn't help too much. Today I went for steak, bread and salad washed down with a beer and am feeling better. I think it all rests and falls on the happy thoughts. It's much easier to think of good stuff when you're eating a steak.
The trouble is that once in a while I will go for steak and happy thoughts when I really am ill, which is no good at all. If there is something really wrong then eating steak will just make you worse, which is an unhappy thought, which is a bad thing to end a post on. I therefore leave you with the words of Oscar Hammerstein.
Happy talk, keep talkin' happy talk,
Talk about things you'd like to do.
You got to have a dream,
If you don't have a dream
How you gonna have a dream come true?
Monday, July 17, 2006
England 824 Pakistan 659 (match drawn)
After five days the Lords test match ended in a draw. I've been in Germany long enough now to see the amusing side of this: a sport which not only takes five days to play, but a sport which doesn't even get a result in five days. In case you are wondering why England didn't win by simply having more runs (824 of them in total), the answer is that Pakistan still had six batsmen left who could have made the difference had the match continued for another day or two.
But five days it is, although the match didn't last exactly five days: with about half an hour left to play both teams decided that they couldn't win, so they packed it in and went for a cup of tea.
Here is a picture from the bbc website of the Pakistani captain, Inzamam-ul-Haq, playing a forward defensive shot. The key to playing this shot is a good pair of trousers. They should be tight enough to not flap around, but elastic and roomy enough to let you take a good step down the pitch. Once you've got the trousers everything else (bat and front leg together, head directly above the ball, bat angled to the floor) will just fall into place.
But five days it is, although the match didn't last exactly five days: with about half an hour left to play both teams decided that they couldn't win, so they packed it in and went for a cup of tea.
Here is a picture from the bbc website of the Pakistani captain, Inzamam-ul-Haq, playing a forward defensive shot. The key to playing this shot is a good pair of trousers. They should be tight enough to not flap around, but elastic and roomy enough to let you take a good step down the pitch. Once you've got the trousers everything else (bat and front leg together, head directly above the ball, bat angled to the floor) will just fall into place.
Friday, July 14, 2006
Experimental techniques.
I studied in physics in York. The three guys in charge of the demonstration experiments were Matt, Pete and Ian. They were all quite accustomed to students and professors who couldn't get things to work, but were always keen to remind you how stupid you were when you appeared with a newly broken piece of apparatus. In their office they had a framed cartoon which summed up their suffering. I made a quick reproduction of this cartoon, which referred to the famous tale of Galileo and his cannon balls.
The cause of my new-found solidarity with lab technicians was an encore of the Stern-Gerlach experiment which was held today. Prof. Dr. X decided to include the experiment in his lecture, and was determined to run the experiment himself, despite the fact that there were four perfectly qualified people standing around ready to press the necessary buttons. The experiment worked, but not as well as it could have. An hour of preparation was almost screwed up because he lacked the coordination to press a key and flick a switch together. Of course he then had several suggestions for how the experiment could be improved. It's not that he's wrong: of course you could improve the experiment. It's just the pomposity of assuming that he's the first person to think of these things.
The cause of my new-found solidarity with lab technicians was an encore of the Stern-Gerlach experiment which was held today. Prof. Dr. X decided to include the experiment in his lecture, and was determined to run the experiment himself, despite the fact that there were four perfectly qualified people standing around ready to press the necessary buttons. The experiment worked, but not as well as it could have. An hour of preparation was almost screwed up because he lacked the coordination to press a key and flick a switch together. Of course he then had several suggestions for how the experiment could be improved. It's not that he's wrong: of course you could improve the experiment. It's just the pomposity of assuming that he's the first person to think of these things.
Thursday, July 13, 2006
Success!
Today I helped run the Stern-Gerlach experiment, and it worked even better than I hoped. Physicists make a distinction between things they are looking for (signal) and things they don't want to see (background). What the layman would call a needle in a haystack, a physicist calls a signal/background ratio of 0.00001.
If you look at this plot then the maximum value (0.21) is nearly four times larger than the minimum value (0.06). This means that the signal is almost three times as large as the background: so this is more of a lamppost in a flower arrangement than a needle in a haystack (if you are a layman) or a signal/background ratio of 3:1 (if you are a physicist).
This background of 0.06 nA doesn't come from the beam and is always present, so in principle you could just subtract this value from all the measurements to see how many atoms come from the beam (this is then your signal). The trouble is that the 0.06 is sometimes 0.058 and sometimes 0.062, and these fluctuations cause the measurement to jump up and down from point to point. The only way to get a really nice measurement is to keep this background very low. This is where the liquid nitrogen cold-trap comes in handy: the more stuff which freezes on to this trap, the less background is seen by the detector, and the smoother your curves are.
If you look at this plot then the maximum value (0.21) is nearly four times larger than the minimum value (0.06). This means that the signal is almost three times as large as the background: so this is more of a lamppost in a flower arrangement than a needle in a haystack (if you are a layman) or a signal/background ratio of 3:1 (if you are a physicist).
This background of 0.06 nA doesn't come from the beam and is always present, so in principle you could just subtract this value from all the measurements to see how many atoms come from the beam (this is then your signal). The trouble is that the 0.06 is sometimes 0.058 and sometimes 0.062, and these fluctuations cause the measurement to jump up and down from point to point. The only way to get a really nice measurement is to keep this background very low. This is where the liquid nitrogen cold-trap comes in handy: the more stuff which freezes on to this trap, the less background is seen by the detector, and the smoother your curves are.
Wednesday, July 12, 2006
For one night only...
Tomorrow is the big day for the Stern-Gerlach experiment.
Roughing pumps: check
Pressure gauge: check
Turbo pump: check
Oven heating: check
The detector is on standby, the liquid nitrogen is still liquid...
As you can see I am a bit excited by the whole thing. To tell you the truth I never really got over the loss of my nice big Stern-Gerlach experiment: If you look at the photo you can see part of the "Atomic beam source" which is a souped up version of the good old Stern-Gerlach device. I'm the guy on the left caressing a cryo pump. It was an emotional affair between me and the Atomic Beam Source, and I got in way too deep. It's not healthy for one man to spend so much time and energy looking after one gizmo.
But tomorrow, for one day, I can be an expert again, and not the poor fucker with broken nerves and broken dreams who does the baker's run. I can be important, needed, coolly guiding the detector wire with an expert hand into the beam of polarized atoms, tuning the oven for optimal intensity...
Please only leave a comment if you have a degree in psychology, or at least saw a talk show with the theme "Men who fall hopelessly in love with plasma-driven turbo-pumped atomic mother-fucking beam sources".
Roughing pumps: check
Pressure gauge: check
Turbo pump: check
Oven heating: check
The detector is on standby, the liquid nitrogen is still liquid...
As you can see I am a bit excited by the whole thing. To tell you the truth I never really got over the loss of my nice big Stern-Gerlach experiment: If you look at the photo you can see part of the "Atomic beam source" which is a souped up version of the good old Stern-Gerlach device. I'm the guy on the left caressing a cryo pump. It was an emotional affair between me and the Atomic Beam Source, and I got in way too deep. It's not healthy for one man to spend so much time and energy looking after one gizmo.
But tomorrow, for one day, I can be an expert again, and not the poor fucker with broken nerves and broken dreams who does the baker's run. I can be important, needed, coolly guiding the detector wire with an expert hand into the beam of polarized atoms, tuning the oven for optimal intensity...
Please only leave a comment if you have a degree in psychology, or at least saw a talk show with the theme "Men who fall hopelessly in love with plasma-driven turbo-pumped atomic mother-fucking beam sources".
Monday, July 10, 2006
Liquid Nitrogen
Today I tested the cold-trap of the Stern-Gerlach experiment. This is just a steel container which holds liquid nitrogen, and is represented as the blue thing in the above diagram. Well it's not quite just a steel container, it's actually a steel container with a pipe welded through it. Only a small proportion of atoms which leave the oven will fly in the wanted direction (straight forwards and through the pipe). Most of the others will hit the cold-trap, and stick to the cold walls. This is good, because they can't cause problems by then flying somewhere they shouldn't.
As part of the intensive research that goes into every post I write here (or actually every post I write soberly here) I typed "liquid nitrogen" into google. What do you think is the top hit? The ubiquitous Wikipedia, maybe, or a company which delivers liquid nitrogen, or a site explaining chemistry and phase transitions of nitrogen? Wrong, wrong, wrong, the top hit is of course "1001 things to do with liquid nitrogen". (Hello Mr. googlebot, by the way).
I'm not really sure if the liquid nitrogen cold-trap is really needed, as the turbo pump is pretty nifty alone. However, someone already explained to me that it is never a bad thing to have liquid nitrogen in your experiment. Even if the experiment doesn't work, you can freeze things, or blow them up, or pretend you're in a disco. And when you've finished you can clean the floor with it. If I ever build a house it will be designed to be cleaned by liquid nitrogen. I think I will need a rather understanding wife.
Sunday, July 09, 2006
Bollocks
I'm back where I was a couple of posts ago. I have a bloated feeling somewhere in my digestive system, and am fucking annoyed. It all started so well on Thursday, with a piece of linoleum, a barbecue and a crate of beer.
Our ex-flatmate Sabine agreed to come over and lay the piece of linoleum in our hall. She is doing an apprenticeship as an interior designer and did a very nice job. I sort of stood around and made encouraging sounds. The hall now looks much nicer, which is great.
Being a sensible sort of person, Sabine is quite happy to work for beer and sausages, so we then moved on to Juliane's birthday barbecue. In short it got quite late and I got quite drunk, and I've been feeling shit ever since I woke up on Friday.
My original plan today was to go cycling and drink a couple of beers whilst watching the final. My depressed-as-fuck backup plan is to eat some mashed potatoes, clean my room and do the washing.
The worst thing about this backup plan is that I have no distractions left. Without beer, world cup, bicycles or Stern-Gerlach experiments the truth is plain to fucking see: I need to get a plan, a job and a future.
Our ex-flatmate Sabine agreed to come over and lay the piece of linoleum in our hall. She is doing an apprenticeship as an interior designer and did a very nice job. I sort of stood around and made encouraging sounds. The hall now looks much nicer, which is great.
Being a sensible sort of person, Sabine is quite happy to work for beer and sausages, so we then moved on to Juliane's birthday barbecue. In short it got quite late and I got quite drunk, and I've been feeling shit ever since I woke up on Friday.
My original plan today was to go cycling and drink a couple of beers whilst watching the final. My depressed-as-fuck backup plan is to eat some mashed potatoes, clean my room and do the washing.
The worst thing about this backup plan is that I have no distractions left. Without beer, world cup, bicycles or Stern-Gerlach experiments the truth is plain to fucking see: I need to get a plan, a job and a future.
Wednesday, July 05, 2006
Stern-Gerlach woohoo!
That is more like it. The guys at the mechanical workshop here rebuilt the motor system so that the detector moves automatically across the beam. Together with Fabian I put everything together and it works. woohoo!
If you've not been following this, check out these previous posts!
Introduction to the Stern-Gerlach experiment.
First measurements, with an explanation of what you can see in the plot.
Hello world.
I'm really drunk (Burp!). Wahey!. Germany 0 Italy 2. I did my best supporting Germany, but they lost, and I don't know if I mentioned that I'm very drunk.
Yours, drunkenly, Phil.
Yours, drunkenly, Phil.
Tuesday, July 04, 2006
Quick Lemon Cheesecake (first iteration)
Disclaimer: I haven't tried eating this yet. This creation is lurking in my fridge. If this should happen to be the last ever post of this blog, I would recommend that you don't follow this recipe.
Ingredients:
1 Packet of hobnobs. You can also use digestives, but I ate the packet I brought along from Hamburg specially.
100g butter.
50g brown sugar.
1 tin of condensed milk.
250ml whipping cream.
2 lemons.
Notes for people residing in Germany:
1/ Hobnobs aren't easy to get your hands on. Handelshof sell Hobbits, which are basically the same. If you are in Hamburg, then the English bookshop in Stresemannstrasse is the place to go for biscuits.
2/ Germans don't seem to make a distinction between "evaporated milk" and "condensed milk". The standard stuff you can buy which is labelled Kondensmilch (Germans put it in their coffee) is what the English call evaporated milk. What we need is condensed milk, which is much sweeter. If you mix sugar into the evaporated milk until it becomes sickly sweet then you get condensed milk.
Instructions:
Crush the biscuits, mix with the butter and brown sugar. Tip this mixture into a flat dish, and press it down.
Mix together the cream, condensed milk and the juice of the lemons. Tip this on top of the biscuit mix.
Put the dish in the fridge and wait for 2 hours.
That's it!
Ingredients:
1 Packet of hobnobs. You can also use digestives, but I ate the packet I brought along from Hamburg specially.
100g butter.
50g brown sugar.
1 tin of condensed milk.
250ml whipping cream.
2 lemons.
Notes for people residing in Germany:
1/ Hobnobs aren't easy to get your hands on. Handelshof sell Hobbits, which are basically the same. If you are in Hamburg, then the English bookshop in Stresemannstrasse is the place to go for biscuits.
2/ Germans don't seem to make a distinction between "evaporated milk" and "condensed milk". The standard stuff you can buy which is labelled Kondensmilch (Germans put it in their coffee) is what the English call evaporated milk. What we need is condensed milk, which is much sweeter. If you mix sugar into the evaporated milk until it becomes sickly sweet then you get condensed milk.
Instructions:
Crush the biscuits, mix with the butter and brown sugar. Tip this mixture into a flat dish, and press it down.
Mix together the cream, condensed milk and the juice of the lemons. Tip this on top of the biscuit mix.
Put the dish in the fridge and wait for 2 hours.
That's it!
Sunday, July 02, 2006
Well played, and good luck to Portugal
Oh dear, England lost a football match. Maybe Rooney was a bit unlucky to be sent off, but we didn't look like scoring in the 60 minutes when we had 11 players, and the team gave a good "backs to the wall" display with 10 men. Over 120 minutes a draw was probably fair enough, as Portugal passed well and had a few chances to win the game too.
You've got to give credit to Ricardo, the goalkeeper of Portugal. He guessed right on all four occasions in the penalty shootout, and made three good saves.
We have to look on the bright side of this defeat:
1/ We actually won games against Paraguay, Ecuador and Trinidad and Tobago.
2/ We got further than Spain and Holland.
3/ We got just as far as Brazil and Argentina.
4/ We are better at taking penalties than Switzerland!
5/ We're going to win the tennis. Come on Andy!
We wuz robbed!
Bleeding diving Portuguese! Stay on your feet for 10 seconds, you feckin' Alice-banded nancy boy. Stood on your bollocks, you say! When I was young we got kicked in the balls at least twice per match and nobody ever complained. Anyway what the feck were your bollocks doing on the pitch to be stood on in the first place:
La da da, I'm Portuguese and need to fall over. Oh no, I fell down in the middle of a FOOTBALL PITCH and there are people running around still. And one of them stood on my knackers!
And as for the ref, what can you expect from an bloody Argy! Carragher taking a Penalty too quickly? What the blazes is he there for? He walks from the half-way line, takes the ball, puts it on the spot, and then surprises the ref by taking a penalty. What did he expect him to do, sit down and have afternoon tea with the goalkeeper? Go on ref, take the Malvinas and stick them where the sun don't shine!
Anyway who gives a damn, we're going to win the Tennis.
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