We’ve recently seen the largest explosion ever recorded: a supergiant star two hundred times bigger than the sun utterly obliterated by runaway thermonuclear reactions triggered by gamma ray-driven antimatter production.  The resulting blast was visible for months because it unleashed a  cloud of radioactive material over fifty times the size of our own star, giving off a nuclear fission glow visible from galaxies away.

The antimatter annihilates with its opposite, as antimatter is wont to do, but the problem is that the speed of antimatter explosion – which is pretty damn fast – is still a critical delay in the gamma-pressure holding up the star. The outer layers sag in, compressing the core more, raising the temperature, making more energetic gamma rays even more likely to make antimatter and suddenly the whole star is a runaway nuclear reactor beyond the scale of the imagination.  The entire thermonuclear core detonates at once, an atomic warhead that’s not just bigger than the Sun – it’s bigger than the Sun plus the mass of another ten close by stars. 

The entire star explodes.  No neutron star, no black hole, nothing left behind but an expanding cloud of newly radioactive material and empty space where once was the most massive item you can actually have without ripping space.  The explosion alone triggers alchemy on a suprasolar scale, converting stars’ worth of matter into new radioactive elements.

And we saw this.  This really happened.  

Brutally awesome.

The arrow of time is based on ideas that go back to Ludwig Boltzmann, an Austrian physicist in the 1870s. He figured out this thing called entropy. Entropy is just a measure of how disorderly things are. And it tends to grow. That’s the second law of thermodynamics: Entropy goes up with time, things become more disorderly. So, if you neatly stack papers on your desk, and you walk away, you’re not surprised they turn into a mess. You’d be very surprised if a mess turned into neatly stacked papers. That’s entropy and the arrow of time. Entropy goes up as it becomes messier.

So, Boltzmann understood that and he explained how entropy is related to the arrow of time. But there’s a missing piece to his explanation, which is, why was the entropy ever low to begin with? Why were the papers neatly stacked in the universe? Basically, our observable universe begins around 13.7 billion years ago in a state of exquisite order, exquisitely low entropy. It’s like the universe is a wind-up toy that has been sort of puttering along for the last 13.7 billion years and will eventually wind down to nothing. But why was it ever wound up in the first place? Why was it in such a weird low-entropy unusual state?

Great stuff.

If you list all your friends, and then ask them all how many friends they have, their ­average is very likely to be higher than your friend count. The reason is bewilderingly ­simple: “You are more likely to be friends with someone who has more friends than with someone who has fewer friends,” as the ­psychologist Satoshi Kanazawa puts it. You’re more likely to know more popular people, and less likely to know less popular ones. Some people may be completely friendless, but you’re not friends with any of them.