Neues vom Nordkap
Ein rohes Ei rollt schneller die schiefe Ebene runter als ein gekochtes. Warum? Mir scheint das zuerst mal nicht sehr intuitiv zu sein. Aus dem "Drehtest" (wenn man ein gekochtes Ei auf der Spitze dreht, so dreht es sich wie ein Kreisel, ein rohes Ei torkelt fast sofort um, so kann man sie unterscheiden. Das gekochte Ei verhält sich wie ein ordentlicher starrer Körper, beim rohen Ei hingegen sind Inhalt und Schale nicht fest miteinander verbunden und wegen der Trägheit der Eimasse rotiert diese nicht ordentlich mit.)
Also auf den ersten Blick würde ich denken, dass beim runterrollen das gekochte Ei im Vorteil ist, weil es sich eben wie ein einziger starrer Körper verhält, irgendwie kompakter ist, das rohe Ei hingegen, ist irgendwie clumsy.
Aber genau der Drehtest gibt eigentlich die Erklärung, warum das rohe Ei schneller ist: Wegen der Trägheit seiner (eigenständigen) Eimasse rollt es eben "schlechter" und hat daher weniger Rotations- und folglich mehr Rotationsenergie.
Barbie könnte ihren Kopf nicht tragen, nicht gehen und hat in ihrem Bauch nicht genügend Platz für alle Organe.
Input, SRF 3 von heute abend
Back to school
I became a big fan of coursera
over the last weeks. Actually, precisely since I am enrolled in the first course there.
I am signed up to the functional Programming class by Prof. Odersky. It's a good lecture, though I warn you, it's lots of work if you watch all lectures and do the assignments properly. I am mostly struggling to submit the solutions the last possible day. :-)
Video lectures are really well done, you see the slights and the teacher putting in some hand written notes as he goes on explaining. The video may stop for some exercises or questions until you answer and hit "go on".
This particular class has nice assignments and a quite good submission and grading mechanism. Though this is through sbt
, and hence probably scala
specific. You submit your solutions via sbt, to a server where a bunch of tests is run on them, including functional and some style checks and then your work gets graded. You can resubmit as often as you like before the deadline ends. They hava feedback pages for the assignments where they discuss the most common mistakes or don'ts they encountered over all exercises.
Give it a try it's not only for programmers, a lot of world class universities participate, and there are courses of any type.
Disillusions of a physicist
Last week when I came back from my Holidays in France there was a rainbow travelling along with the train all the way from Romont all the way to Zürich.
Next to me there was an elderly couple. She was very enthusiastic about it. "Look, a rainbow! Oh wow, there are even two!"
I was smiling to myself and left them with their illusions: it was exceptional because the rainbow was very bright, you could see the entire arch most of the time. But there are always two. The second on is at a fixed angle from the first one and is fainter. That's why you can't always see it, but it's always there. They come from the first and secondary breaking angle in the water drop.
a propos Arbeitsbedingungen
bei Samsung und so...
Would you buy a Samsung or an Apple device?
I would buy a mozilla phone and heavily fine all companies engaged in silly patent battles. They should rather invest
that money on better working conditions on their production sites or planting flowers and on their parking-lots...
I was at the Sigur Ros concert
(openair) in Winterthur on Saturday. The rain was ennoying, but hey, without it, they would not have spoken to the audience not one sentence. So at least we got a "Nice you are all here despite the rain, feels very much home, like in Iceland" or something.
Now that (the do-not-bother-with-speaking-thing) felt really like Iceland, indeed.
The concert was great, their music gets a real wild when played loud. You could feel Alfadrottningen standing just a fingertip away.
I should include her into my great-female-scientist gallery.
Electronics made in Britain
After quite some time where I could listen to music only from my ipod or my kitchen radio, I upgraded a bit: I am now the proud owner of two Rowen
loudspeakers which I got second hand for a good price, powered by fine British electronics. Yes, it's all made in Europe and you hear it.
The other day I was nearby in the kitchen, when I heard a something falling to the ground in the living room. I run over to see what ghost was messing with my things. Well, the clanking sound was on the CD...
I have a Sugden Mystro
amplifier, which is the baby model by Sugden. They normally build equippment which you can use to boost a church-sized room to party level ... And take it at Sugden, they are into building fine electronics and not waste their time with anything else. The mystro is just an amp, without any schnickschnack: you can choose the input source, and adjust the volume, that's it. Oh and then there is a power button and a manual.
Just three sheets of A4 sized paper stitched together in the corner. It gives you some technical details in Watts and Ohms, and any other kind of useful information, like
Depressing switches the power on. Pressing again switches the power off.
Love it, I really do.
Brother DCP-145C unter Ubuntu installieren
Der Druckertreiber fuer den Brother DCP-145C ist nicht in Ubuntu 10.04 dabei, auch nicht in den brother...-common und brother...-extra packages. Treiber von Brother runterladen
sudo mkdir -p /var/spool/lpd/dcp145c/
sudo dpkg -i dcp145clpr-1.1.2-2.i386.deb
sudo dpkg -i dcp145ccupswrapper-1.1.2-2.i386.deb
Andere Treiber die in den packages dabei sind etwa fuer den DCP-150C oder den DCP-135C funktionieren nicht!
Wenn der olle laptop wiedermal nicht bootet
Mein Schlepptop ist uralt und alle paar Monate passiert es. dass er nicht mehr bootet.
- Ubuntu CD einschieben, CD booten, (nicht direkt installieren)
- die Laufwerke mounten (sda1, sda5 oder so), Home auf externe platte sichern.
- Ubuntu installieren waehlen.
- wenn man gefragt wird, gemountete Partionen nicht unmounten.
- Es ist nicht offensichtlich, wie man in eine bestehende Partition rein installieren kann.
in Partitionstabelle 1. Auswahl ausgewaehlt lassen, es sollte dann (hoffentlich) eine Meldung kommen, dass irgendwas irgendwo nicht geht und man kann back druecken, dann kriegt man eine mount tabelle, wo man die sda1 als "/" mounten kann und die Daten Partition als "/home" so eintragen und abfeuern.
- Drucker installieren
As you probabely know the idea of there being more than 4 dimensions is a very persistent one in speculative physics. Most prominently there is string theory which needs 11 dimensions, but there are many other fancyful ideas. (Which are a bit more economical in the number of dimensions they need). Me myself I work on such a model for my PhD.
Normally, the dimensions d > 4 are discussed away from every day experience by claiming that they are compact and small and hence we cannot walk into them. They only unfold for a very high energetic probe.
At least in popular books these ideas are illustrated with a picture like this:
That is people tell you that you should imagine a small circle or (something more complicated as in the picture) attached at each point in your 4d space. That is you think of some lattice like in the picture, attach your circles and then take a continuum limit, ie let the circles move closer and closer together. Not so difficult is it? But this is blatantly wrong. Because according to this picture you have a compactified space at each point on the plane, but once you move into this plane, you get detached from the surface holding it. Whereas in reality at each point in the compact manifold there also extends the extended plane again. And from there it continues until you get mad.
That is to say the above picture is very different from the one of a infinite cylinder of radius R:
In the cylinder, which is extended in 1 dimension and compact along another, when you move along the circle at every point you have a inifinite line. Staying whith this two dimensions the above picture would correspond to a straight inifinite line, where there are circles attached at each point. So at every point in the line you are free to move into the circle or to continue along the line, but once you have left the line and entered a circle, there is really only one direction open to you until you have walked all along the circle.
Or take a torus (donut) which is 2 dimensional and compact in both directions. Each point is the intersection of two circles. The thing above isn't such.
Honestly, I can imagine 3 dimensions because that's the space I live in, and then I am fine with the fourth, because I know what time is, but all the other things I have no intuitive grasp.
J'ai pris l'image de ce site.Merci
My name is Magdalena Luz.
I am a physicist, now working as a software engineer in Zürich, Switzerland.