Star Updated 2025-07-16
Astronomical unit Updated 2025-07-16
Apparent magnitude Updated 2025-07-16
Proper motion Updated 2025-07-16
Volume Updated 2025-07-16
Solving partial differential equations with the Fourier series Updated 2025-07-16
See: math.stackexchange.com/questions/579453/real-world-application-of-fourier-series/3729366#3729366 from heat equation solution with Fourier series.
Separation of variables of certain equations like the heat equation and wave equation are solved immediately by calculating the Fourier series of initial conditions!
Gas chromatography Updated 2025-07-16
This technique is crazy! It allows to both:You actually see discrete peaks at different minute counts on the other end.
- separate gaseous mixtures
- identify gaseous compounds
It is based on how much the gas interacts with the column.
Detection is usually done burning the sample to ionize it when it comes out, and then you measure the current produced.
Gas chromatography by Quick Biochemistry Basics (2019)
Source. Visualizing the Riemann hypothesis and analytic continuation by 3Blue1Brown (2016) Updated 2025-07-16
Good ultra quick visual non-mathematical introduction to the Riemann hypothesis and analytic continuation.
Identity theorem Updated 2025-07-16
Essentially, defining an holomorphic function on any open subset, no matter how small, also uniquely defines it everywhere.
This is basically why it makes sense to talk about analytic continuation at all.
One way to think about this is because the Taylor series matches the exact value of an holomorphic function no matter how large the difference from the starting point.
Therefore a holomorphic function basically only contains as much information as a countable sequence of numbers.
National Institute of Standards and Technology Updated 2025-07-16
These people are serious.
United States Department of Energy Updated 2025-07-16
Good targets for amateur astronomy Updated 2025-07-16
Looking at most astronomical object through a telescope is boring because you only see a white ball or point every time. Such targets would likely only be interesting with spectroscopy analysis.
There are however some objects that you can see the structure of even with an amateur telescope, and that makes them very exciting.
Some good ones:
- The Moon, notably crater detail.
- Saturn. Clearly visible to the naked eye, but looks like a ball. But under an amateur telescope, you can clearly see that there is a disk. Clearly discerning that the disk is a ring, i.e. seeing the gap, is a bit harder though.
- Jupiter. Clearly visible to the naked eye, it is quite huge. The four Galilean moons, being Earth-sized, are incredibly clearly visible, tested on Celestron NexStar 4SE 25mm/9mm eyepiece. Colored gas clouds are hard though, you will likely just see it bright white. www.reddit.com/r/telescopes/comments/35xrbb/how_can_i_see_the_color_of_jupiter_with_my/
- a double star. As mentioned at www.relativelyinteresting.com/10-astronomical-targets-new-telescope/ Albireo are incredibly separated. Also it is is easy to find manually being in a major well known constellation. It is no wonder it is not quite even known if they are gravitationally bound or not!
- Andromeda Galaxy. This is when things start getting hard. You can see a faint cloud, but it is not super clear that it has a center.One important understanding is that it is not possible to see stars outside of the Milky Way by naked eye.It is at this point that you start to learn that pictures of faint objects require longer term exposure and averaging of the images taken. For this you need:Just looking through the scope to immediately see something is not enough.
- a digital camera attached to the scope
- a computerized scope that slowly moves to track the point of interest
- image processing software that does the averaging
Video "Andromeda Galaxy with only a Camera, Lens, & Tripod by Nebula Photos (2020)" gives a good notion of expectation adjustment.
Alternating current Updated 2025-07-16
Direct current Updated 2025-07-16
Transcendental number Updated 2025-07-16
Sometimes mathematicians go a little overboard with their naming.
Big Bang Updated 2025-07-16
Actor Updated 2025-07-16
Regular 4-polytope Updated 2025-07-16
Epic Rap Battles of History Updated 2025-07-16
Most of the videos are crap, but the following ones almost killed Ciro Santilli of laughter:
- Video "Bill Gates vs Steve Jobs by Epic Rap Battles of History (2012)"
- Video 1. "Rasputin vs Stalin by Epic Rap Battles of History (2013)"
Rasputin vs Stalin by Epic Rap Battles of History (2013)
Source. See also: cirosantilli.com/china-dictatorship/stalin.Monty Python has a few precursors to the "random famous people mixed together compting" format, although not in the rap fight format:
Communist Quiz by Monty Python (1970)
Source. Has a Wiki page: en.wikipedia.org/wiki/World_Forum/Communist_Quiz. Brings to mind: Video "Football, Football, Football by Mitchell and Webb". YouTube poop Updated 2025-07-16
- www.youtube.com/channel/UCDyR_C_QVjZR24ze0fl5S_Q Goat-on-a-Stick channel
Afraid of Technology by adarkenedroom (2008)
Source. TODO source show, appears "Brass Eye", TODO episode www.reddit.com/r/videos/comments/jpyfi/technology_scares_the_crap_out_of_me/ There are unlisted articles, also show them or only show them.