system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5: how do fire detectives find the start of a large fire? Is it more burnt in that specific area where it started somehow?
gpt
>	is it more burnt

That’s a big part of it.  If you’re investigating a house fire and you can see that the end of the house where the garage is has been almost completely burned away but the bedroom end is intact, there’s a very good chance that the fire didn’t start in the bedroom.  So then you can start investigating what’s left of the garage for an ignition source.  

Same thing with brush fires.  If you’ve got a huge field that burned, absent any wind or changes in fuel density, the origin point will be near the middle of the burned area.  If there is wind, you can guess where the origin is based on wind speed and direction.