Schrödinger equation for a one dimensional particle Updated +Created
We select for the general Equation "Schrodinger equation":
giving the full explicit partial differential equation:
Equation 1.
Schrödinger equation for a one dimensional particle
.
The corresponding time-independent Schrödinger equation for this equation is:
Yeast artificial chromosome Updated +Created
Silk Road investigator Updated +Created
How to hardcode subtitle into a video with FFmpeg? Updated +Created
On Ubuntu 20.10, just:
ffmpeg -i input.mp4 -vf "subtitles=subtitle.srt" output.mp4
To change font size: stackoverflow.com/questions/21363334/how-to-add-font-size-in-subtitles-in-ffmpeg-video-filter
ffmpeg -i input.mp4 -vf "subtitles=subtitle.srt:force_style='Fontsize=64'" output.mp4
The default appears to be 24, so just multiply that by whatever seems like a reasonable factor.
Note howver that .ass subtitle files can contain style information, which ffmpeg respects. Aegisub can produce and preview such styles, making .ass one of the best options.
Dirac equation Updated +Created
Adds special relativity to the Schrödinger equation, and the following conclusions come basically as a direct consequence of this!
Experiments not explained: those that quantum electrodynamics explains like:
See also: Dirac equation vs quantum electrodynamics.
The Dirac equation is a set of 4 partial differential equations on 4 complex valued wave functions. The full explicit form in Planck units is shown e.g. in Video 1. "Quantum Mechanics 12a - Dirac Equation I by ViaScience (2015)" at youtu.be/OCuaBmAzqek?t=1010:
Then as done at physics.stackexchange.com/questions/32422/qm-without-complex-numbers/557600#557600 from why are complex numbers used in the Schrodinger equation?, we could further split those equations up into a system of 8 equations on 8 real-valued functions.
Video 2.
PHYS 485 Lecture 14: The Dirac Equation by Roger Moore (2016)
Source.
Skew-symmetric form Updated +Created
3D rotation group Updated +Created
Particle in a box Updated +Created
Quantum tunnelling Updated +Created
Examples:
Supercomputer by owner Updated +Created
Superfluid helium-4 Updated +Created
Also sometimes called helium II, in contrast to helium I, which is the non-superfluid liquid helium phase.
How to store data in the Bitcoin blockchain Updated +Created
There are apparently two methods:
Specific implementations:
Light cone Updated +Created
The key insights that it gives are:
  • future and past are well defined: every reference frame sees your future in your future cone, and your past in your past cone
    Otherwise causality could be violated, and then things would go really bad, you could tell your past self to tell your past self to tell your past self to do something.
    You can only affect the outcome of events in your future cone, and you can only be affected by events in your past cone. You can't travel fast enough to affect.
    Two spacetime events with such fixed causality are called timelike-separated events.
  • every other event (to right and left, known as spacelike-separated events) can be measured to happen before or after your current spacetime event by different observers.
    But that does not violate causality, because you just can't reach those spacetime points anyways to affect them.
Figure 1.
Animation showing how space-separated events can be observed to happen in different orders by observers in different frames of reference
. Source.
Display manager Updated +Created
Check which you you have:
systemctl status display-manager.service
Tested on Ubuntu 23.10 I see:
● gdm.service - GNOME Display Manager
     Loaded: loaded (/lib/systemd/system/gdm.service; static)
     Active: active (running) since Sun 2023-12-24 10:34:50 GMT; 23min ago
    Process: 1827 ExecStartPre=/usr/share/gdm/generate-config (code=exited, status=0/SUCCESS)
   Main PID: 1850 (gdm3)
      Tasks: 4 (limit: 71817)
     Memory: 6.8M
        CPU: 119ms
     CGroup: /system.slice/gdm.service
             └─1850 /usr/sbin/gdm3
which means I have GNOME Display Manager.
EC2 instance type Updated +Created
Amazon's informtion about their own intances is so bad and non-public that this was created: instances.vantage.sh/
How to teach / Explain why the subject is beautiful Updated +Created
And if you really can't make money from a subject, there is only one other thing people crave: beauty.

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