Mastodawn

I have a problem with grading student talks and submissions based on the popular method of having a list of fixed criteria which give a certain number of points each, which are then added up.

Think something like

completeness 4
correctness 6
slides are pretty 3
time management 3
...
---
-------------------
60 pts

My problem with this approach is summarized best by an old Hagar the Horrible cartoon where they find a castaway guy on a remote island who claims to have survived by eating stones. "Sure, they are very hard to digest, but very easy to catch!"

In other words, if a talk completely sucks in a crucial way, does it make sense to say, sure it's all factually wrong, but the slides are pretty and time management was perfect, so you get a B.

How to solve this? One would need Multipliers instead of just adding points.

#education #physicsedu #fediLZ

Show thread

Alexander Knochel Dec 25

The wisdom of the masses has (barely) prevailed!

Indeed the Gluon, the force carrier of quantum chromodynamics, was discovered at the Positron Elektron Ring Anlage PETRA in Hamburg in 1979.

What was seen concretely was a three jet event. The light particles involved in strong interactions are never seen in isolation because when you try separating them, for instance two quarks, the binding energy simply produces more in-between particles. For this reason, when you make two quarks, what you see in the detector are two showers called jets of many particles produced in the subsequent in-between strong interactions after the quark pair is produced and flies away in opposite directions.

If you make quarks all you ever get is an even number of jets. Gluons however are predicted to radiate off quarks like photons would with charged particles, and an extra gluon can thus add a third jet to the two quark jets.

That's precisely what was observed back then at DESY

#physics
#physicsedu
#science
#scicomm

Alexander Knochel Dec 24

Merry Xmas, happy Holidays!

Here's interstellar comet 3I/ATLAS as of this early morning 2 UTC, flying by what looks like an interestingly shaped galaxy just below, and a double star to the left - I'll check the fits file later what they are exactly

Again scheduled on the LCO network by my student under the Schools' Observatory grant, supported by FTP Europlanet and Dill Faulkes' foundation.
#astronomy
#physicsedu

Alexander Knochel Dec 22

Now that the Quantum year 2025 comes to an end, let me show off some nice (professional grade) toys we got sponsored by the Heraeus Foundation: A class set of material for Michelson and Mach-Zehnder interferometers and a quantum crypto demo experiment. Fun times!

#physics
#physicsedu

Show thread

Alexander Knochel Dec 14

and here today's 13:52 UTC 3I/ATLAS false color composite green, red, infrared from the LCO 1m Sinistro.

Again, the background stars and galaxies appear as multiple colored dots because of the comet's movement during and between exposures.

#astronomy #physics #physicsedu

Alexander Knochel Dec 14

Interstellar Comet 3I/ATLAS as of this morning, false color composite of r,g,i,z filters, taken with Las Cumbres 2m MUSCAT telescope.
#astronomy #scicenceedu #physics #physicsedu

Alexander Knochel Dec 10

Oh look, it's our first attempt to quickly image the jet caused by the now famous central black hole of M87.
A student proposed the target today and voilà, not so bad for a couple minutes of exposure per color.

#astronomy #physicsedu

Alexander Knochel Oct 30

Spoiler: It really depends on its mass and the precise dark matter distribution in the galaxy. For light Dark Matter candidates the answer is most likely yes, only for candidates which are much heavier than the weak scale, the average number of particles in a room would be below one. I calculated that dark matter particles with the weight of a Coronavirus would come in at a good order of magnitude below one per living room, so anything lighter than that would be present at each moment.

BUT as DM is probably moving with >100 000 m/s relative to us, so even if there are below one in the room at each given instant, there may be many visitors flying through per second...

#astronomy #physics #darkmatter #scicomm #physicsedu