system
Given the following post, respond as if you're commenting on Reddit:
human
Could someone explain why gravity doesnt fit in with other areas of physics for a unified field theory?

Thank you for thinking about answering my question!
gpt
There are four fundamental forces that we know of. Three of them appear to be 'quantized'. This means that they come in discrete packets. In other words, there is a single "unit" of light energy (plank's constant) that is fundamental and indivisible. This is analogous to zooming in on light and finding out that it's pixelated¹.

Gravity, on the other hand, resists quantization. Quantized gravity equations go haywire and give you infinities. This is analogous to zooming in on gravity and finding out that it's continuous.

Different people have different intuitions about whether the universe is pixelated or continuous at the small scale, but it can't be both: our continuous model of gravity doesn't work with our pixelated model of light (& the other forces) on scales where there is a lot of energy in a small space (e.g. black holes).

¹ Pixelated in terms of how much energy it carries, not in terms of its literal position. Position still seems continuous, which is directly related to why gravity is continuous. See below.