Newtonian Gravity is a feature that allows the user to simulate gravity as it is in real life. You must turn it on from the menu.

Originally in the game, there were two elements, BHOL (Black-hole) and WHOL (White-hole) which produced negative and positive pressure, respectively. These have been changed. They are now titled "VACU" and "VENT", again, respectively. The elements which now hold the names of BHOL and WHOL are a little bit more complex than a vent and a vacuum. They act like their real life counterparts. A black hole, sucking matter out of space, and a white hole, spewing it back out again. These produce a grid, displaying the power levels of the gravity. The bigger the BHOL or WHOL, the larger the grid, and therefore, the larger the gravity. Primarily, these are used to bend PHOT and NEUT (Light and Radiation, respectively.)

By bending the light, people are now able to create curving photons. Here is one example And here is another

Gravity Modes

Gravity modes control where particles in the simulation fall. These modes are not related to Newtonian Gravity - they let you change the default "fall down" behavior of particles.

There are three gravity modes:

Vertical

This is the usual gravity mode - every particle falls down.

Here's a video displaying it.

Radial

This is an interesting gravity mode that makes everything fall towards the center. Particles might behave a bit weird and form other shapes instead of a sphere - just quirks of the particle engine.

Here's a video displaying it.

Off

There's no gravity in the save at all! Newtonian Gravity and air effects will still move particles around, though.