In the original version of this post that was displayed to me, the text preceding the image just said "Nick is right." I assume it was posted prematurely and then fixed later. But given the cache that @johncarlosbaez has for those of us who started talking physics online back in the usenet and early web days, I really should have had the presence of mind to get a screenshot of that original version. 
@internic @BartoszMilewski @j_bertolotti - Nick is right. You can see it clearly from here if you remember that light moves along 45 degree lines.
@internic - first I merely said "Nick is right". Then I realized it would help @BartoszMilewski more if I pointed him to the easy way to follow your reasoning, or do that sort of reasoning himself.
@johncarlosbaez Weird, it seems like in some places this isn't showing up with the quoted post, so I guess I'll include a link to the post in question.
https://mathstodon.xyz/@johncarlosbaez/113527722998969250
Attached: 1 image @internic@qoto.org @BartoszMilewski @j_bertolotti - Nick is right. You can see it clearly from here if you remember that light moves along 45 degree lines.
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