The question and Answer software called ‘Quora’ had some quite interesting debate about aliens. I am bowled over by how many, and some are quite educated, believe in aliens. Particularly that they have been here and not just that, are still here and doing great intelligent things like making crop circles. I have to be honest here and say that yes there are aliens except we will never see or hear them. As probability will tell you that with trillions of galaxies, having billions of stars the likelihood of other life is near to 100%. The problem is that life such as ours on Earth needs to move but in such a way as is possible on Earth. That is to say, a gravity of 1, oxygen to breathe and food of a kind that is digestible. The next thing to consider is movement, meaning star travel. It is pretty clear that life such as on Earth is not really around in our solar system. We might find some microbes but that’s about it. The distances between the star systems even in our local space area, are so vast and would take hundreds of years to get somewhere. There is no return. Even contact via radio, laser or whatever radiological type will be hampered by these distances. Besides we, humanity that is, have only sent out signals since about the latter part of the 19th century. These signals have not travelled far yet. So any 'local' aliens have not heard of us yet. Then again someone will say, what about alien visits because they probably have technology far in advance of ours. Humanity is not very advanced on the scale of intelligent life. But forgetting that, why would an alien super techno race visit us? Literally no reason at all, we have absolutely nothing to excite such super beings. The only thing I could comprehend they would need to replenish is ‘water’. Yes, water because all life seems to need that first and foremost. So, there you go, no aliens, no visits, we are alone in our solar system. But keep looking, at least there is some employment for Prof Brian Cox.