math is simply a working model of the observed

math doesn't try to explain why

math also allows predictions without understanding why

it's a placeholder to get things done

ie. correction factors

Einstein thought the universe was static but his math would not fit

So he made a "cosmological constant" to make static universe math fit

Hubble later used science to figure out the universe was expanding, not static

Einstein said "whoops" and threw out the constant

Except his math was right even without understanding why, it was just a model of the observed

The "cosmological constant" actually measures dark energy without even knowing what it was

Pretty amazing IMHO