Size matters ...

Yes, we are alone in the universe. I don’t mean that there is no-one else there; we share just this planet with around seven billion other humans, and who can say that orbiting the hundred thousand million, million, million stars in the visible universe, there are not many planets with civilizations containing almost countless individual sentient beings?
 
The essence of each one of us, is trapped inside a bony sphere connected to the outside world by a few sensors – sight, hearing touch etc. But each of those ‘senses’ consists merely of a series of electrical impulses transmitted to our brains, which then interpret what is being seen, heard, felt etc. Inside our skulls we are completely alone …
 
And how much space are we alone in? Several Greek philosophers proposed that the stars were just like the sun only much further away, and Giordano Bruno was burned at the stake in 1600 for making the same prediction. But Christian Huygens – the man who invented the pendulum clock – in a book published posthumously in 1698, described measuring the distance of Sirius, the Dog Star. He used a set of very small apertures in his telescope to reduce the brightness of the sun to that of Sirius, and concluded that Sirius was 27,664 times further away – assuming that the Sun and Sirius have the same intrinsic brightness.
 
Actually, Sirius is much brighter than the Sun, but even so, Huygens’ estimated distance of the star was only two or three times less than the currently accepted figure of 8.6 light years. A truly astonishingly result. It was not until the 1830s that Bessel was able to measure the distance of the stars directly; the nearest star to us, Proxima Centauri, is four and a third light-years away, or about 25 million, million miles. The Voyager 1 spacecraft, launched in 1977, and currently travelling out of the Solar System at over 37,000 miles per hour, would take nearly 77,000 years to get there. We are alone in an awful lot of empty space …