Cosmic Inflation

[Summerlander]

Black holes could still, in theory, hold universes inside. According to the holographic theory, our world is the gossamer reflection of an information-rich hypersurface that makes up a surrounding cosmic frontier; postulations here appear to be reinforced by the fact that the quantum realm is fuzzy.

As for the Sun, I really couldn't tell you where it gets all its energy; solar research is an ongoing project where the prevailing view is that the star is converting much of its hydrogen into helium. The input of its existing energy, beyond the molecular cloud that formed the solar system, is hard to tell. Physicists have been smashing particles with surprising results that at first appeared to be magical: Imagine orchestrating the collision of two light subatomic particles at high speed only to beget a third which is heavier than its quantum progenitors—this is analogous to the crash of two Ferraris producing a ship as large as the Titanic! But then we take into account, not just the mass of the initial objects, but also the speed, the momentum, the force of impact, etc., and it all adds up (to the surprising result)!

And this takes us right back to cosmic inflation and a question that I think Alan Guth figuratively asked, which was, 'Who paid for the ultimate free lunch?' We know that one gram of inflating matter turns into two grams of inflating matter (paradoxically doubling) and yet no laws of physics are broken! In other words, mass can be created from nothing. Einstein provided a loophole here with special relativity where, famously, E=mc2 (E is energy; m is mass; c is 299,792,458 metres per second, or the speed of light).

Now here's a clincher: the speed of light is such a large number and that's why a tiny amount of mass corresponds to a huge amount of energy. Example: less than a kilogramme of mass released the energy of the Hiroshima nuclear blast! What does all this mean? You can increase the mass of something by adding energy to it. Example: a rubber band can be made slightly heavier by stretching it—applying energy to stretch it means the energy goes into the rubber band and increases its mass. So ...

The rubber band has negative pressure because you need to work to expand it; for a substance with positive pressure, like air, it's the other way around: you need to do work to compress it. In summary, the inflating substance has to have negative pressure in order to obey the laws of physics, and this negative pressure has to be so huge that the energy required to expand it to twice its volume is exactly enough to double its mass.

Puzzlingly, one might point out, inflation causes accelerated expansion. So how do we unpack this? Gravity is, undoubtedly, an attractive force, so if we have expanding stuff, shouldn't gravity decelerate it? Einstein saves the day with general relativity theory, which says that gravity is caused not only by mass, but also, by pressure. Since mass can't be negative, the gravity from mass is always attractive. But positive pressure also causes attractive gravity, which means that negative pressure causes repulsive gravity!

An inflating substance has huge negative pressure. Guth calculated that the repulsive gravitational force caused by its negative pressure is three times stronger than the attractive gravitational force caused by its mass, so the gravity of an inflating substance will blow it apart!

I know it is a lot to digest, but just let me finish this by saying that inflating substance produces an anti-gravity force that blows it apart, and the energy that this anti-gravity force expends to expand the substance creates enough new mass for the substance to retain constant density. This process is self-sustaining, and the inflating substance keeps doubling its size over and over again. In this way, inflation creates everything we can observe with our telescopes from almost nothing. This is what prompted Guth to refer to our universe as 'the ultimate free lunch': inflation predicts that its total energy is very close to zero.

And then we realise that the same mechanism that produced our universe could very well have produced many; in fact, to assume it only produced one seems absurd! Here's an analogy for this: our universe is a mini and, as we forensically examine the vehicle's properties, we come to realise that a car factory produced it, and as we theorise about the factory's properties and functions, we begin to conceive, with our mathematical minds, an infinite cornucopia of distinct vehicles that this Hilbert space factory must surely be still churning out for there is no scientific reason why it should stop.

Here's another mind-blowing analogy from Tegmark: imagine a bunch of fish in a tank who think water is immutable space that pervades all existence and couldn't be any other way because it's fundamental; and then there is an Einstein fish who figures out this 'watery space' represents one phase in a possibility of three (ice, liquid, gas).

Analogously, we live in a universe where most humans believe space itself couldn't be any other way. However, the most intelligent of us figured out that our laws of physics are not fundamental—they are only locally effective—and that space itself can in fact exist in a number of phases that far exceed the googolplex.

And the realm of mathematics, which describes every structure in existence, can outdo human imagination, and has probably created worlds well beyond what is depicted in Rick'n'Morty ...