The British satirist Douglas Adams once observed: “Space is big. You just won’t believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it’s a long way down the road to the chemist’s, but that’s just peanuts compared to space.”
In fact, one wonders if space isn’t there just to smack a little humility into the human species if we were only smart enough to pay attention (then again that’s a bit like believing the earth was the centre of the cosmos, so best not go there).
Space is indeed big, and small for that matter, but let’s leave the quantum world for another day and examine what should breed a humble twitch or two into human awareness from the big side of things.
The edge of the observable universe is currently about 46 billion light years from earth, which seems strange given that the universe is only 13.8 billion years old.
Remember, though, that whatever we are seeing way out there isn’t there anymore – we are looking backward in time to where and what it was 13.8 billion years ago.
Our universe is constantly expanding, so it’s even bigger than when I wrote this column.
So, how far is something that is 46 billion light years away? Really, really, way out there, far. An online calculator tells me that it is something like 4.4 x 1023 kilometres. Doesn’t mean much?
Well, a very rough estimate of the number of grains of sand on all the beaches in the world is over seven quintillion grains (7.5 followed by 19 zeros, or 1019).
That means the number of kilometres is about 5,867 times the number of all those grains of sand.
You aren’t driving there for a beer, that’s for sure. And we are only talking about the observable universe.
If cosmologist Alan Guth of Massachusetts Institute of Technology (M.I.T.) is right, the total universe that includes the bits beyond what we can ever see, because the light will never get to us is something like 10(1030)times what we can see.
That’s insanely big. We are such a tiny speck in the universe that in statistical terms we really are meaningless in the grand scheme. For all our sense of self-importance, we almost don’t exist.
When you gaze romantically at the clear night sky, and your eyes are still good, you’ll see a few thousand stars, the brightest lot in a small patch of our galaxy. It’s extremely hard to count the number of stars in our galaxy – impossible actually – so it’s done by calculating the mass of the galaxy, subtracting estimates of the other stuff like planets and black holes, and dividing by the average size of the stars.
It’s obviously more complicated than that, but I wouldn’t understand it and surely couldn’t explain it, so you’ll have to be content with the simple bit.
Regardless, the experts vary in their calculations, estimating somewhere between 100 billion and 400 billion stars and some estimates are much larger. That’s our galaxy.
Now, the Hubble Telescope surveys have resulted in estimates that range from 200 to 400 billion galaxies. So, there are a whole lot of galaxies, to say the least. We now know that planets are common in the universe – ergo, there are a lot of planets. A lot more than those grains of sand.
Size and number isn’t all that makes the universe “big” … it also has big, powerful and scary things. One of them sits in our neighbourhood and is just beginning to show up in our winter sky.
Betelgeuse is the star that forms one shoulder of the constellation, Orion (the one on our left).
Betelgeuse is big. It’s a red giant and according to the European Southern Observatory, if it were our sun, it would fill the space past the orbit of Jupiter. Mercury, Venus, Earth, Mars and Jupiter simply wouldn’t be.
But, Betelgeuse is also a dying star and any day now (in cosmic terms) it is going to suffer a death spasm called a supernova.
It is 65 light years away, so we aren’t in danger, but when it does blow up, it will produce an amazing light show.
For a period of weeks to months, it will shine like a second sun. In fact, it will probably bang out more light than all the rest of the stars in our galaxy combined, and even it won’t be close to the biggest of the universe’s supernova shows.
Betelgeuse will end its life seeding the universe with heavy elements as it collapses way, way down into an exotic, neutron star that in itself will be a wonder of galactic construction.
It will spin like a giant, city-sized top, have a magnetic field that would hold up star-sized fridge magnets and a thimble full of the neutron star stuff will weigh more than the entire human population of the earth.
The bigger-than-Betelgeuse, giant stars collapse into black holes, creatures that are even weirder than neutron stars.
Now, none of this big stuff should make you feel depressed – it’s not depressing. No matter how insignificant we are, we really are here – I think, anyhow – and we should be caring about us (although we’re not doing a very good job of that, now are we?).
It’s just that we really don’t matter in the universal overview, and that should keep us humble (I’m back to that humility thing), not afraid.
It should encourage us to love what we have, nurture our environment and treasure our humanity.
We occupy an infinitesimally small, blue marble in a vast ocean of strangeness and while we are small we still have managed to reach out and probe deeply into that strangeness.