<i>What measurement would have convinced you that it is impossible for humans to cross the Atlantic in under a day</i><p>A reliable measurement of the speed of light (supposing of course that we still knew SR). If the result were smaller than width of atlantic &#x2F; 1 day, I&#x27;d have been convinced that transatlantic travel must take &gt; 1 day.<p><i>You pre-supposed that, and then didn&#x27;t try to understand what I was saying.</i><p>True - my initial theory is that your views are faith based. I then made a measurement that could prove me wrong; I asked you what evidence could change your views. Had you stated concrete measurements then I&#x27;d have had to change my theory.<p>Since my theory predicted reality perfectly I don&#x27;t need to change it.<p>As for why I don&#x27;t attempt to predict your views, that&#x27;s a trap. If you were arguing in bad faith then whatever measurement I proposed (and then refuted) would result in you simply accusing me of not &quot;try[ing] to understand what I was saying&quot;.