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u/abstractanus

3,021 post karma · 695 comment karma · joined Oct 2019

  1. 10points

    Manim animation of solution to Schrodinger's equation using separation of variables. (self.manim)

    submitted Jul 2022 by u/abstractanus to r/manim

    4 comments

  2. 217points

    Why identical galaxies can look bigger yet fainter at high redshift: Tolman's (1+z)^4, animated [OC] (v.redd.it)

    submitted 13d ago by u/abstractanus to r/astrophysics

    11 comments · source

  3. 17points

    Past a certain distance, galaxies stop looking smaller and start looking bigger. (youtube.com)

    submitted 14d ago by u/abstractanus to r/cosmology

    4 comments · source

  4. 9points

    I made a film on angular diameter distance, D_A = chi/(1+z), and the teardrop shape of our past light cone (youtube.com)

    submitted 14d ago by u/abstractanus to r/3Blue1Brown

    2 comments · source

  5. 2points

    Animation of a light wave stretched to twice its length by expansion (1 + z = 2), from a film I made (v.redd.it) [Astro Art (OC)]

    submitted 14d ago by u/abstractanus to r/Astronomy

    1 comments · source

  6. 14points

    I made a film on how the apparent size and surface brightness of distant galaxies change with redshift (youtube.com)

    submitted 14d ago by u/abstractanus to r/astrophysics

    0 comments · source

  7. 73points

    Why the Most Distant Galaxies Look Bigger (youtube.com)

    submitted 14d ago by u/abstractanus to r/space

    15 comments · source

  8. 302points

    The apparent size of an identical galaxy falls with distance, bottoms out near redshift 1.6, then rises (i.redd.it)

    submitted 14d ago by u/abstractanus to r/educationalgifs

    13 comments · source

  9. 60points

    Luminous light-cone shell rendered in Blender for a cosmology film I made (v.redd.it) [Original Content Showcase]

    submitted 14d ago by u/abstractanus to r/blender

    1 comments · source

  10. 11points

    I made a film on our past light cone in proper distance and why galaxies beyond redshift 1.6 look bigger! (youtube.com)

    submitted 14d ago by u/abstractanus to r/pbsspacetime

    0 comments · source

  11. 9points

    What ladder operators add to the quantum oscillator's eigenvalue problem (self.LinearAlgebra)

    submitted 21d ago by u/abstractanus to r/LinearAlgebra

    1 comments

  12. 1points

    Two constructions of the quantum oscillator's eigenbasis: power series and ladder operators (self.mathematics)

    submitted 21d ago by u/abstractanus to r/mathematics

    0 comments

  13. 6points

    Connecting the oscillator spectrum to stationary states, superpositions, and coherent states (self.quantummechanics)

    submitted 21d ago by u/abstractanus to r/quantummechanics

    3 comments

  14. 2points

    A predict-before-watching prompt for a quantum-oscillator animation (self.physicseducation)

    submitted 21d ago by u/abstractanus to r/physicseducation

    0 comments

  15. 2points

    Feedback on explaining a stationary quantum-oscillator state without implying the particle is motionless (self.PhysicsHelp)

    submitted 21d ago by u/abstractanus to r/PhysicsHelp

    2 comments

  16. 4points

    Why the quantum oscillator has discrete energies: two animated derivations (self.learnphysics)

    submitted 22d ago by u/abstractanus to r/learnphysics

    2 comments

  17. 2points

    Teaching the quantum oscillator: contrasting two derivations and a moving coherent state (self.PhysicsTeaching)

    submitted 22d ago by u/abstractanus to r/PhysicsTeaching

    4 comments

abstractanus 1 points · 11h ago

Thank you!

abstractanus 2 points · 14d ago

I made this luminous shell in Blender for a 12-minute film. It is our past light cone drawn in proper distance against cosmic time, which gives it the teardrop shape.

The rest of the film uses my custom Python renderer (NumPy, OpenCV, Pillow), with the edit in DaVinci Resolve.

Full film, with the story around this shape: https://www.youtube.com/watch?v=5XTHyWVwHVY

abstractanus 0 points · 14d ago

Check it out! https://www.youtube.com/watch?v=5XTHyWVwHVY&t=100s

abstractanus 1 points · 21d ago

Thanks! On the density, the distinction is between a single energy eigenstate and a superposition. For a time-independent Hamiltonian, one energy eigenstate gains an overall phase, but its position probability density stays fixed. In the particular ground-state/first-excited-state superposition shown in the video, the changing relative phase makes the density move. That contrast is what the animation is meant to make visible.

abstractanus 2 points · 21d ago

Thank you! Glad you enjoyed it.

abstractanus 1 points · 21d ago

For a concrete oscillator example of the weight-function step in your comment, take hbar = m = omega = 1. Starting from

-(1/2) psi''(x) + (1/2) x^2 psi(x) = E psi(x),

and writing psi(x) = exp(-x^2/2) y(x), the equation becomes

y''(x) - 2x y'(x) + (2E - 1)y(x) = 0.

The Hermite-polynomial solutions then give E = n + 1/2. Their orthogonality with weight exp(-x^2) becomes ordinary wavefunction orthogonality after absorbing the square root of that weight. It is a useful place to make the change of inner product explicit. Boundary conditions and operator domains still matter; matching formal differential expressions alone does not determine the spectrum.

I recently made an animation of this standard oscillator example, including the power-series and ladder-operator derivations and the resulting state evolution: https://youtu.be/7_DcdXVh5mc (my video, about 13 minutes). The visual connection may be useful for readers coming to the differential-equation formulation from linear algebra.

abstractanus 0 points · 22d ago

Thanks! That’s fair on the music, I’ll probably dial it back a bit in future videos. And nope, it isn’t AI-generated. I made the animations in Manim. Appreciate you watching and giving feedback!

abstractanus 1 points · 22d ago

Thank you!! Really glad that came across - that was one of my favorite parts to animate