Atheism VS Christianity

13: The Beginning, part 2.

Hi folks! Today we have something a little different for you. If you’re one of those who pay attention to the debates in the comments, you will recall that Ariador and Mckenzie had yet another interesting chat about the Big Bang, leading to yet another chapter on the subject. Enjoy!
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Ariador: Hello world, Jasper here. You exist, so you are something, right? Like… you’re not nothing. But what if I told you that you are? No, I don’t mean to be derogatory… like, I am nothing, we all are nothing, the whole universe is nothing… everything is nothing with a twist. The whole universe came out of nothing.

I know, this idea may sound bizarre. Like… the universe began with the Big Bang, right? Also energy in a system remains constant, so how could all of this have come from nothing. But the physicists argue that it follows naturally from science's two most powerful and successful theories: quantum mechanics and general relativity.

Quantum mechanics tells us that there is no such thing as empty space. Even the most perfect vacuum is actually filled by a roiling cloud of particles and antiparticles, which flare into existence and almost instantaneously fade back into nothingness. These so-called virtual particles don't last long enough to be observed directly, but we know they exist by their effects. For example, the effective charge of the electron is different from its naked charge.

From tiny things like atoms, to really big things like galaxies. Our best theory for describing such large-scale structures is general relativity, Albert Einstein's crowning achievement, which sets out how space, time and gravity work. Relativity is very different from quantum mechanics, and so far nobody has been able to combine the two seamlessly. However, some theorists have been able to bring the two theories to bear on particular problems by using carefully chosen approximations.

One thing they have found is that, when quantum theory is applied to space at the smallest possible scale, space itself becomes unstable. Rather than remaining perfectly smooth and continuous, space and time destabilize, churning and frothing into a foam of space-time bubbles. In other words, little bubbles of space and time can form spontaneously. If space and time are quantized, they can fluctuate, so you can create virtual space-times just as you can create virtual particles. What's more, if it's possible for these bubbles to form, you can guarantee that they will. In quantum physics, if something is not forbidden, it necessarily happens with some non-zero probability.

So it's not just particles and antiparticles that can snap in and out of nothingness: bubbles of space-time can do the same. Still, it seems like a big leap from an infinitesimal space-time bubble to a massive universe that hosts 100 billion galaxies. Surely, even if a bubble formed, it would be doomed to disappear again in the blink of an eye?

Actually, it is possible for the bubble to survive. But for that we need another trick: cosmic inflation. Most physicists now think that the universe began with the Big Bang. At first all the matter and energy in the universe was crammed together in one unimaginably small dot, and this exploded. This follows from the discovery, in the early 20th century, that the universe is expanding. If all the galaxies are flying apart, they must once have been close together.

Inflation theory proposes that in the immediate aftermath of the Big Bang, the universe expanded much faster than it did later. As weird as it seems, inflation fits the facts. The idea is that, a fraction of a second after the Big Bang, the quantum-sized bubble of space expanded stupendously fast. In an incredibly brief moment, it went from being smaller than the nucleus of an atom to the size of a grain of sand. When the expansion finally slowed, the force field that had powered it was transformed into the matter and energy that fill the universe today. Guth calls inflation “the ultimate free lunch”.

As weird as it seems, inflation fits the facts rather well. In particular, it neatly explains why the cosmic microwave background, the faint remnant of radiation left over from the Big Bang, is almost perfectly uniform across the sky. If the universe had not expanded so rapidly, we would expect the radiation to be patchier than it is.