system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars]Are there any earth material/substances that a lightsaber couldn't cut through.
gpt
It appears these other two did not read the question...

I do not think so. Some harder/more dense elements and isotopes (diamonds, perhaps) might take a while to cut through, but nothing naturally occurring on Earth will hold a lightsaber off for more than a few seconds.

Some alloys (titanium?) will last a while longer, but still eventually be melted.