“What we mean by ‘right now’ is a mysterious thing which we cannot define and we cannot affect, but it can affect us later, or we could have affected it if we had done something far enough in the past. When we look at the star Alpha Centauri, we see it as it was four years ago; we might wonder what it is like ‘now.’ ‘Now’ means at the same time from our special coordinate system. We can only see Alpha Centauri by the light that has come from our past, up to four years ago, but we do not know what it is doing ‘now’; it will take four years before what it is doing ‘now’ can affect us. Alpha Centauri ‘now’ is an idea or concept of our mind; it is not something that is really definable physically at the moment, because we have to wait to observe it; we cannot even define it right ‘now.’ Furthermore, the ‘now’ depends on the coordinate system. If, for example, Alpha Centauri were moving, an observer there would not agree with us because he would put his axes at an angle, and his ‘now’ would be a different time.” – Richard P. Feynman, The Feynman Lectures on Physics, Vol. I (emphasis in original)