Douglas Adams’The Hitchiker’s Guide to the Galaxy garners a fair slice of modern pop cult references, and perhaps its most famous ‘bit’ is the answer to the ultimate question of the universe, the meaning of life and everything, 42.

In the book a supercomputer called Deep Thought calculates this answer over a period of 7.5 million years. The simplicity of the answer certainly puzzled me and I’d imagine has caused more than a few head scratches over the years.

If we investigate a little we might find 42 is quite a cool number. Not for any human reason, spiritual or religious, it doesn’t carry particular mathematical significance; however we find it appears in the tapestry of nature. In fact it appears to be the rivet that literally holds everything together.

Two forces dominate the universe at the macro and micro scale, namely gravity and the electric force. Together these forces form stars, stop you from dissolving through your chair and are responsible for pretty much everything we see before us. What’s interesting is that gravity and electricity are both very similar in the fact they are inverse square forces, that is, fields, which exist around particles. Electric fields exist around all matter that possesses charge, gravity around all matter that has mass. So particles can have both or one, but never neither so far as we can tell. So the universe is a massive web of melding gravitational and electric fields, which are influencing you, but also being produced by you. These fields also stretch out right to the edge of the universe, from every particle.

Now take the elementary unit of charge nature has given us, the electron. This is a fundamental particle, you cannot ‘chop it up’, it’s a key building block of nature. Now we can understand the relationship of gravity to electricity (in force terms) by comparing the strength of its gravitational and electric fields. The relative strength of these is fixed in the electron, which is one of the commandments of the universe engraved so to speak, in its properties.

We find that funnily enough the ratio is about:

4.2 × 10⁴²

A naïve observer may assume this to be an arbitrary number. It essentially says the electric force is billions upon trillions of times stronger than the gravitational force, and this ratio is fixed into the fabric of the universe. Unchanging since the big bang, so it seems.

The ratio underpins the behaviour of our universe in its entirety. A strong electric force stops the earth from collapsing into a black hole, prevents you from sinking into your chair, gives water its lifegiving properties (hydrogen bonds), allows ionic processes in the body to power chemical reactions which drive life, bonds the strands of DNA, and so on. For all these phenomona the electric force must easily overcome intertia.

It also means life on earth is fairly simple. Everyday objects are solid, but exert no gravitational influence on you. This stops the fruitbowl from pulling your head towards it at several meteres per second. It means you can pick things up, and move around on the solid surfaces provided by powerful electric bonds. While the weak gravity means that you are pulled to the surface along with all objects at a gentle acceleration of g, keeping things in a certain order.

Further the ratio allows for fusion to occur in stars. If the electric force wasn’t so strong gravity, or more likely the strong nuclear force would overcome it at every opportunity and every atom and molecule in the universe would fuse in an instantaneous, but completely destructive flash of light. With the ratio as it is stars conveniently form only when huge amounts of mass are gathered (and thus gravity). Only when there is this huge push of gravity can stars fuse elements to produce light, and in supernovae explosions, the matter that constitutes you and I. If they didn’t do this the complex heavier elements that are necessary life wouldn’t ever be made in the universe. It’d be a very dull place indeed.

Fortunately they are, and again, we can thank the ratio of gravity to the electric force. This is incidentally why stars can become black holes too, or white dwarfs.

So we see that if you were to design your own universe, which you’d hope would host some lifeforms if not intelligent ones, the first question you would have to ask yourself is; to what ratio should I tune gravity and electricity?

(Or technically you’d ask, what order of magnitude should electric forces be stronger than gravitational ones?)

And the answer would be:

42

And you’re new universe would cook up stars, water, humans and finally Donald Trump in a few billion years. Well done.

Aside: Also of interest is the fact that the ratio the time it takes a photon to pass across the elementary unit of distance to the age of universe is also of the order 42. This has lead some theoretical physicists to believe that there is some relationship between gravity and the age of the universe, however it remains a mystery, as do both fields. Nobody knows how they even transmit force!

Richard Feynman (Nobel prize winning physics dude) said that if you managed to produce a fundamental equation of everything it would have to feature this number in, even though it appears so arbitrary to a human glance, 42 is most likely the most important number in physics.

*I didn’t do all the legwork for this alone by any means. In Feynman’s lecture 7 on Gravitation he talks about the ratio of the electrons charge to its mass, and how this is, he believes, the most important relation in nature. I suspect Douglas Adams listened to the same lecture before writing his book, I’ve uploaded it here, if you want the 42 bit go to the last 15 minutes. Feynman has the gift of genius and the mouth to transmute it to the simpler realm of metaphor and speech, he’s so good at it that I can assure you fifteen minutes won’t be enough. http://www.filedropper.com/showdownload.php/v1ch07theoryofgravitation