Good question, I touch on this on the same comment, in the paragraph starting with "I keep repeating these things on HNs".
The TLDR is that you can never expect the same level of certainty when you don't have direct experiments, but you can still rule out _some_ hypothesis, and see how far other hypothesis take you. This is called theoretical physics. Just because you can't make an experiment doesn't mean you can't do anything.
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Good question, I touch on this on the same comment, in the paragraph starting with "I keep repeating these things on HNs".
The TLDR is that you can never expect the same level of certainty when you don't have direct experiments, but you can still rule out _some_ hypothesis, and see how far other hypothesis take you. This is called theoretical physics. Just because you can't make an experiment doesn't mean you can't do anything.