inflation-simulation

Have you ever wondered "How far away will my screams reach?"? Well, here is the ultimate answer. It doesn't get any less causally connected than this. Here we introduce INFLATION SIMULATOR 9000. Be it that you started screaming at the beggining of the universe, of rather late (during radiation dominated era) we can tell you how far away they will ever reach!

Download

To run a pre-compiled version of the game, download and unzip the file for your OS from the releases page: https://github.com/rjrosati/inflation-simulation/releases/latest . Then double-click the executable. For Mac and Linux the executable is named universe, on Windows it's universe.exe.

Controls

The simulation will begin paused.

• SPACE starts/pauses the simulation.
• ENTER speeds up time by a factor of 10 while held down
• Left click release a shell of light where you click.
• p toggles the plot of a(t)
• h toggles the display of the causal horizon (i.e. the max comoving distance the current light ray could travel in infinite time)
• e ends inflation and switches to radiation domination
• g GODMODE, sets view to comoving coordinates.
• r resets the simulation to the initial conditions at t=0
• m toggles music

Things to try:

• Causal horizon: Switch to GODMODE. Start a light beam. Notice how the light beam will never reach the causal horizon. End inflation. Causal horizon will skyrocket, why do you think that is?
• Look at the plots in the two modes: NOTICE THE INTERSECTIONS: Your screams could hardly be heard during inflation but radiation era brings them back to those distant places!!!

To run from source

To download this script, click on the green "clone or download" button right above the list of files. If you have git installed, you can clone the repository, or you can download the current version as a zip file.

Installation

If you don't have Python installed, we recommend you install the Anaconda distribution (for Python 3), which comes packaged with numpy. https://www.continuum.io/downloads

You'll then need to run pip install pygame.

Running the script

On Mac or Linux, open a terminal in the script's folder and type

$> python ./universe.py

On Windows, hold down Shift and right-click in the script's folder. Choose "Open Command Window Here". Type:

C:\Users\...\inflation-simulation> python universe.py

Some warnings:

The units are arbitrary at the moment. A switch to Planck units will be coming in the near future.

We are not solving the full FRW equations here, especially not when switching from inflation to radiation domination. If we solved the full equations of motion, we wouldn't be able to stay in inflation arbitrarily long. You might notice some irregularites if you end inflation before a(t)=10 or so (like light going backwards). This is an artefact of the approximations we are using and isn't physical. If anyone has an easy fix, feel free to message or submit a pull request.

The music is Hybrid Song from TeleportProkg.