what evidence can support the idea that light can travel through a vacuum?
I'll just give you a hint: Do you think you have ever seen light that has already traveled through a vacuum before it reached you? Do you know of any place where there's a vacuum all the time?
And if you need more hardcore evidence (ie mathematical) look towards the man they called Maxwell. His equations show that there does not need to be a medium for electromagnetic waves to travel through.
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