Low grade panic was an early prediction, with bulk buying of toilet paper, an association that happened early in the Covid pandemic. I was watching a TV programme speculating on events following evidence of an alien entity passing through our solar system.
Significant contact with sentient aliens themselves would be unlikely. In the absence of other life in our solar system, the nearest point of possible origin would be the Proxima Centauri solar system. It's some 4.24 light-years from Earth, a distance of 1,469,656,385,121 miles, that would take about 6,300 years to travel using current technology. This, accepting a human generation time of 20-30 years, would mean between 210-315 generations. The initiation of the Proxima Centauri alien's original efforts as postulated would mean that the Earth visit initiation would have been 4.24 years ago in our time frame and they would only be able to receive our reply in 8.48 years' time. Would they or we bother? Certainly no-one should panic.
Given that life (an organismic state characterised by capacity for metabolism, growth, reaction to stimuli and reproduction) is probably something that molecules will create given a suitable opportunity, there must be numerous life forms in the universe, even if the relevant numbers quoted are wildly incorrect. The chances of extra-terrestrial life are high: there are estimated to be at least 100 billion stars in our galaxy and probably all stars have planets, not all of which could sustain life as we know it. There are six to a possible 22 trillion galaxies in the universe. There are thus more stars in the observable universe than there are cells in our bodies (an estimated 37.2 trillion).
Almost certainly there is life out there, possibly intelligent life, but time and distance makes it unlikely that we (that is, you and I in our lifetimes) will ever know.
We presume life, terrestrial or alien, once established, will persist and would spread. Tardigrades (the most resilient animals known) will probably survive us all and will probably inherit what remains of earth after humans have disappeared. In any event, life on earth will vanish when our sun becomes a red giant in about six billion years' time.
What would alien life, as opposed to alien artefacts (inanimate probes like Voyager 1 that is about 15 million miles from Earth), look like if they visited us 'in person'? They would almost certainly not be persons even if they were personable.
The chances are that intelligent life has developed somewhere and sometime else. What would intelligent alien life forms be like? Your guess is as good as mine. Almost certainly they would not be anything like humans. They would have been shaped by their evolutionary history. If, for example, they came from a planet covered by water, they might well be fishlike. Indeed, if a meteorite had not struck the Yucatan peninsular 66 million years ago 'we' might all be dinosaurs.
If there is alien life in the far reaches of our galaxy then, by the time we become aware of it, the alien civilisation or our civilisation might have been destroyed or destroyed itself. Time considerations imply that, even if we and they survived, they (and we) would have evolved beyond the sender and recipient organisms.
It is doubtful if alien contact would be with carbon-based life forms. My guess is that it would consist of silicon-based life, 'metacomputers' or something even more developed, that may look back on carbon-based life forms in much the same way that we look back on our more primitive ancestors.
Aliens could communicate with us by using faster than light communication but this is unlikely unless some unimagined technology is discovered. Quantum entanglement depends on the fact that defining a characteristic of one entangled particle can instantly alter the definition of its entangled particle no matter what the distance (do not bother with YouTube presentations that purport to explain quantum entanglement because they merely describe it). However, quantum entanglement exhibits faster than light phenomena, Einstein's 'spooky action at a distance', but this would not constitute transmission of information.
There may be tricks to circumvent this 8.4 year problem. Perhaps Arthur C Clarke's famous monolith (in 2001: A Space Odyssey
) that had been left on Earth could have contained an entangled entity that, when investigated by intelligent creatures 'us', who observed the status of our entangled entity, would thereby instantly change the status of its entangled entity, thus notifying the alien initiators that intelligent life had developed on Earth years ago.
Given the huge numbers of possible planets in the observable universe, the minute chances that you exist become irrelevant, yet here you are. All your ancestors, right down to unicellular organisms, reproduced at least once, that your mitotic ancestors (a single parent cell divides to make two daughter cells) and meiotic ancestors (cell division that is the basis for sexually reproductive dual parent organisms) reproduced at particular moment at a particular place, and that one of between two and five million human sperms succeeded in the race up fallopian tubes to fertilise the egg that became you.
Despite all these statistics, humanity has the arrogance to think we are special. Some think they, as opposed to lesser animals, might have subsequent immortality. Perhaps we should invest in toilet paper companies whilst awaiting alien contact.
Philip D Welsby is a transient hairy bipedal life form sharing ancestors with unicellular and multicellular organisms