&gt; Only at the bleeding edge, which you don&#x27;t need to use in your everyday life.<p>He means how do you know the speed of light is 186,000 mi&#x2F;sec? Did you test it yourself? Or are you taking someone&#x27;s word for it? It&#x27;s one or the other.<p>&gt; On the other hand, religion&#x27;s basic building blocks require faith from the outset.<p>I think you and the guy above you used the wrong word. Instead of faith, I would have used &quot;trust&quot;. I <i>trust</i> that Einstein and his peers who studied his work are correct in their assessment of his theory of relativity. I don&#x27;t need to test it myself, I take their word for it. I trust them.<p>On the other hand, people who compare something like string theory to philosophy really have it backwards. String theory might be untestable right this second due to technical limitations (string theory does make quite a few unique predictions) but that doesn&#x27;t mean it will remain that way forever. Hell, it may not be that way tomorrow with as fast as science has been progressing... This is in contrast to proving the existence of a God or deity which has <i>zero</i> hope of ever being testable because it&#x27;s &quot;inherently&quot; untestable.<p>As far as string theory goes, one of the most obvious predictions are strings themselves. We cannot build an accelerator large enough to smash particles together at the speeds required to look for strings but that doesn&#x27;t mean such a thing is impossible; such an accelerator already exists - supermassive black holes. They accelerate particles at the required speeds to look for strings.