Hello, SFIA audio listeners, in this month's Nebula exclusive, Big Alien Theory,

we're asking the reason alien civilizations might be rare is because most aliens are huge.

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They say nothing travels faster than light, and yet virtually all of the universe is moving

away from us faster than light can travel out of the edge of the universe.

So today we are continuing our Fast and Light series by traveling all the way out to the

edge of our universe and also asking what we mean by edge and how many edges we might actually

have. As a fairly notorious skeptic about ever harnessing fast and light travel, beating entropy

or making perpetual

motion machines, I find it a bit ironic how often I have to tell folks about the big,

glaring exceptions to these concepts, and the physical laws that make them apparently impossible.

The first law of thermodynamics tells us energy is neither created nor destroyed, that it merely

changes in type, with that

energy being fundamentally conserved, but energy is not conserved, not in all cases, and we have

known that for over a century now, nearly as long as we know the laws of thermodynamics.

It is implicit in the Big Bang cosmology that our universe began at some point, with lower

entropy than now, and with the same energy as now where none was before.

We can say maybe it came from somewhere else, as is sometimes suggested for dark energy, but

...