Is there anybody out there?

I think we’re all agreed that the universe is a big place. Huge. A lot of people think London is pretty big, but let me tell you, the universe is bigger. I mean, it’s fairly easy to cross from one side of London to the other over the course of a day, but Google Maps does’t even cover the universe, it’s that big.

So, if it truly is so vast, are we the only ones in it? If not, why haven’t we heard from anyone?

The answers are: highly unlikely, and the laws of physics.

Do you have any idea how long this fringe takes to get right? It's not logical.

Let me expand. 

The universe that we can see contains billions and billions of galaxies. Each of those galaxies contains billions and billions of stars. That’s a lot of stars. This we know.

Now, the likelihood of each of those stars having a planet or planets that can sustain life (in any form) is rather small, but let’s crunch a few numbers and see what we come up with. Don’t panic, I’ll do it, you can just watch. 

I’m going to use some made up numbers, but this is purely for illustrative purposes, to give you a flavour of the scales that we’re dealing with.

Say we had a nice round number of 100 billion galaxies. That’s 100,000,000,000 galaxies (we’ll use the american version of billion, for the pedants out there).

Now, they're all different, but let’s say that each of those galaxies had a nice round number of stars each. Let’s use 100 billion again. Working that out means that in the observable universe there would be 10,000,000,000,000,000,000,000 stars.

If we now say that only one in every 100 thousand of those had a planet orbiting it that was capable of supporting life that still leaves 10,000,000,000,000,000 cosy, warm planets.

Then let’s say that only one in every 100 thousand of them had actually developed life. That’s 10,000,000,000 bubbling cauldrons of life.

Only one in every 100 thousand of them has a life form that rises to sentience without getting wiped out by either themselves or some natural disaster? Ok, well that still leaves us with 10,000. For those still with me that’s 10 thousand versions of sentient life out there! Beings that have self awareness and methods of communicating abstract ideas - I gossip, therefore I am, that sort of thing. Beings that can look up at the stars and wonder what's out there. Beings like us.

Please remember, these are numbers I have plucked randomly from the ether and I have chosen easy to work with figures so as not to challenge my meagre mathematical skills. In reality the numbers may be vastly bigger, the variables may be wildly different and I may have over-egged the scarcity of life in the universe, but I hope this gives you some idea of how ridiculous the notion is that we are alone. 

So why haven't we heard from them? (For the conspiracy theorists and UFO enthusiasts out there, consider this: if aliens had made it to our planet already, why would they keep it secret? If they have the technology to cross the distances between the stars there is little to no possibility that we would pose a threat to them. Do you hide from ants?) The answer is that the laws of physics as we currently understand them make it very difficult. 

Nothing can travel faster than the speed of light, so meaningful communication over the distances involved is impossible. The light of the sun takes around 8 minutes to reach us and that's right next door. On galactic scales light is quite pedestrian, so what we're seeing now is the past, in every direction. Unless somebody can challenge the well-tested laws that Einstein showed us and discover some way around the speed limit of the universe then any conversation is going to be very, very slow.

Let's say that there is another civilisation out there, only 200 light years away (a light year is the distance light will travel in one earth year - extremely close as far as the universe is concerned). It's capable of sending and receiving the sort of messages we're talking about. To them we will simply be another little white dot in the night sky. They will not yet have any idea that we are even here as the first time we sent any powerful signals into the void is only in the last century. If we had sent it 100 years ago, at the speed of light, it would still only be half way there! They'd receive it in 100 years, send a reply, and we'd know there's someone listening after another 200 - the year 2314 by our calendar. Who wants to take first watch?

What if they're more advanced than us? Better technology, hundreds of years ahead of us? They've been broadcasting for a long time already? They are still (as far as we know) limited by the same laws of physics. The chances of anyone being close enough for us to yet see it are ridiculously small (astronomically small, some might say), and even then their transmitter would have to have been pointing in our general direction in the sky and powerful enough to not get lost in the background noise from the rest of the cosmos.

As for ships crossing the void? The amount of time it would take to get here means it would have to be a very important trip to head this way, as that's quite an investment in every respect. Seeing as we didn't wake up and shout hello until recently it's probably unlikely we'll be seeing Mr Spock any time soon. There would have been no reason to explore this star system up to this point as, apologies, our sun is pretty average in the scheme of things. We're out on the edge of one arm of the Milky Way, hidden by our mediocrity. We're the second cousin of Jar-Jar Binks on the stage of the galaxy.

So, are we alone in the universe? I doubt it. Will you or I ever get to shake tentacles with someone from another planet? I doubt it. Will we, should we, keep trying? Hell yeah. I for one would love to try a Pan-Galactic Gargle Blaster.

A final thought. You are special, don't ever let anyone tell you differently - there's only one of you. You are an extremely rare anomaly in this wondrous, unimaginably huge cosmos that we live in. But you are also part of something. Look up at the stars. We may not ever get to talk to the beings that are out there, but isn't it amazing to think that somewhere among all that emptiness someone might just be looking back?