THE KARDASHEV SCALE. 

We have no idea what an alien civilization would look like. Humans are evolved primates. What if an alien species is reptilian? Or more like an insect? Or a hybrid of these? Or maybe something completely unique that we couldn't even imagine.  

There is only one set of universal laws that every species must follow. Physics. Specifically energy.  

One way to measure a civilization is by its energy consumption. This is done with the Kardashev Scale.  

By using the Kardashev Scale, we can address some big questions about alien civilizations. Like: Fermi's Paradox. It's estimated that there are 40 billion Earth-like planets in the Milky Way that could support life. Certainly a few of these should have given rise to intelligent life. And if so, where is everyone?  

A recent study done by researchers at JPL and CalTech states that when a civilization finally reaches a certain point on the Kardashev Scale, it destroys itself. Which is why we haven't discovered any evidence. They're gone.  

And the Kardashev Scale addresses the most worrisome theory of all. If there are advanced civilizations in our universe, it's probably best if we don't make contact with them.   

Let's find out why.