I woke up on a beach to the most vivid night sky I’ve ever seen.
A vast spread of stars and galaxies filled my view, and I just lay there alone in the middle of nowhere with the biggest smile on my face; feeling totally tiny and insignificant and awestruck at the same time. It was one of the most beautiful and powerful experiences of my life.
I’m hardly unique to have this kind of story. It’s one of the universal human experiences: to stare up at the stars, and be filled with awe at the vastness of the Universe. From the ancient writers of the Psalms to the astronomer Carl Sagan, it’s something we’ve all seen and felt.
Stars give us perspective. For a few minutes, we remember that we are small, that all of our most urgent problems are really just vapour and soon forgotten, that we are one microscopic part of something much grander and more complex than we can ever comprehend.
There’s an old story in the Jewish scriptures, where God promises a man named Abraham that he will have a great number of descendants. In the story, God challenges Abraham to count all the stars in the sky; if he could count them, he would be able to count all the members of his future family. There’s a hell of a lot of stars out there; in the same way, he would be the father of a massive nation.
What the writer didn’t know then was that all the stars we can see are only a tiny percentage of the stars in our own galaxy. In fact, without the aid of a telescope or a pair of binoculars, only around 9000 stars are visible from Earth in the very darkest conditions, and only half of that amount at any one time (depending on what hemisphere you’re in).
Most of those 9000 stars fall within a very small local part of our galaxy, the Milky Way. In comparison, the total actual number of stars in our galaxy alone is somewhere between 200 and 400 billion.
The total number of stars in the Universe?
It’s estimated to be around 1 septillion.
Blank look on your face?
Yeah, me too. If I write it out, a septillion looks like this;
Which again, doesn’t really help. Well how about this.
Picture every grain of sand on every beach on the whole of planet Earth. There are more stars in the Universe than all those grains of sand.
Now, take one of those grains of sand, place it on your finger, and hold it up to the sky at arms length. The Hubble Space Telescope zoomed in to a patch of sky as big as that grain of sand, and this is what it found:
Every single speck of light in that photograph is an entire galaxy, each one made up of billions of stars.
In the space of one grain of sand.
Contemplating the stars gives us some much-needed perspective. When we’re confronted with such huge numbers, and the vastness of reality, it forces us to see ourselves a little differently.
So, for this third issue of The Allowed, we’re going to look at getting some perspective, in three different ways; first we’ll look at time, then we’ll look at space, and finally we’ll look at ideas.
The human brain is not built to easily contemplate massive numbers, whether it’s the amount of stars in the Universe or the distance between solar systems or the number of molecules in a drop of water.
The same goes for contemplating time. We can easily imagine a year, a decade, even a century if we need to; but once you start talking about hundreds of thousands, millions, and billions of years, our brains just kind of fuzz up.
The Universe is estimated at being 13.8 billion years old. I don’t know about you, but I can’t really picture how old that is beyond ‘really freaking old’.
We need a picture to help us get perspective, like the ‘more-stars-than-grains-of-sand’ example above. To help us understand the lengths of time we need to talk about, it’s easier to scale them down to something we can grasp. So for that purpose I’m going to introduce you to a friend of mine: Mrs Old Lady.
Mrs Old Lady is 80 years old today. She’s lived a good, full life. And to help us out she’s going to represent the age of the Universe.
Here’s my thinking: if we could scale the whole 13.8 billion years of time into one 80-year human life, maybe it would be easier to grasp exactly how much time we’ve been around for.
So if Mrs Old Lady was born when the Universe started, and turned 80 in the present day, each year of her life would count as 172.5 million (ish) years of real time, and every day in her life is roughly equal to 471,000 years of real time.
Let’s take a look at the story of Mrs Old Lady & The Universe:
Let’s take a moment to appreciate this.
Every person you ever knew,
every story you ever heard,
every piece of history or technology or art that you interacted with,
every ancient myth and holy scripture,
all comes from the final 15 minutes of the final day of an 80-year life.
If you stretch your arms out to either side of you as far as you can, with your arm span representing the whole time that Earth has been around (4.5 billion years), and then file off just the edge of one fingernail, you will have wiped out the whole of human history.
By the time Mrs Old Lady reaches 85, photosynthesis will have stopped, which means that the oxygen on Earth will run out. And by the time she hits 90, there will be no more liquid water on Earth, and the possibility of any life still existing will be extremely small. Luckily, in real time, that still gives us another 800 million years or so of oxygen.
Pretty crazy to think about hey? But as huge and scary as time is, it’s nothing compared to the second part of this article.
This one will really make you feel small.
Space is even harder to grasp than time, because the numbers we’re working with get much bigger. When it comes to time, even though we’re talking in terms of billions, at least we’re still counting in years. Our Universe is so intensely massive that we’ve had to introduce a whole new set of terms to measure it; the Astronomical Unit (AU), the Light Year, parsecs, kiloparsecs and megaparsecs.
No single scale (like Mrs Old Lady) is enough to make sense of it; for this section, we’ll have to keep scaling up as we go.
But one quick (and important) note before we start: What do we mean when we say ‘The Universe’? There are two real definitions:
#1 – The Observable Universe
The Observable Universe is everything we are currently able to see.
Light travels at about 300,000 kilometres (or 186,000 miles) every second. That’s freaking fast. We use a measurement called a ‘Light Year’ to mean the distance that light travels in one year. (Somewhere around 9 trillion kilometres).
So, light from a star that is 1,000 light years away from Earth takes 1,000 years to reach us. This means that we see that star as it appeared in the past, when the light left it 1,000 years ago.
Simple so far?
As we saw in the last section, our Universe is 13.8 billion years old. This puts a limit on how far we can see; we can only see objects whose light has taken 13.8 billion years or less to get to us. Objects that are more distant are currently invisible to us on Earth, but as more time passes, more parts of the Universe will reveal themselves as their light finally reaches us.
So, how big is the Observable Universe? Well if you’re anything like me, you’d guess 13.8 billion light years in each direction from Earth, which makes a grand total of 27.6 billion light years from end to end, right?
This can get confusing, but there’s a surprising fact about our Universe that was only discovered in the last few decades: the Universe is expanding. Everything is moving farther away from everything else, like a balloon being blown up.
Because of this expansion, objects that sent their light towards us 13.8 billion years ago are now much farther away from us. This gives us a kind of ‘boost’ in the distance we are able to see, and makes our current Observable Universe a huge 93 billion light years across.
#2 – The Universe
While the Observable Universe is everything we can currently see, ‘The Universe’ is everything that exists, has existed, or will exist in the future. It’s size is unknown, but it seems likely to be infinite; or at least to have no edge, so that if you were to travel far enough, you’d end up back where you started.
This is fairly hard stuff to get your head around, and that’s kind of the point. When we talk about the size of the Universe, we’re talking about the infinite, the unknowable, the absolutely indescribably vast… but what the hell, let’s try to describe this beast!
Before we go big, let’s look at things on a smaller scale. You’re probably aware that all matter in the Universe is made up of tiny particles called atoms, and that these particles are made up of even tinier particles called protons, neutrons and electrons.
These can be further broken down into quarks and leptons, which seem to be the fundamental building blocks of matter; but there may be even smaller parts still waiting to be discovered.
So exactly how small are these particles?
To picture the amount of atoms in a grapefruit, imagine if you could hollow out the Earth and fill it with blueberries. The number of blueberries in the Earth would be the same as the number of atoms in that grapefruit.
And quarks are way smaller than atoms. Let’s take a grain of sand again. That grain of sand is halfway in size between a quark and the planet Jupiter.
The average human contains 7 billion billion billion atoms. This is more than the septillion stars in the observable Universe.
In other words, you are a walking Universe of atoms.
Let’s start zooming out a bit by looking at our local neighbourhood: the Solar System. We’re all familiar with most of the basics, but what you may not be aware of is how massive it actually is.
You’ve probably seen maps or images that look a little like this:
It’s a cool picture, but it’s also completely inaccurate. Everything has been zoomed in and squashed together so that you can see all the planets at once.
In reality, the planets are so far away from each other that if we kept the Sun the same size as it is in the image above (around 10cm in diameter), we’d need the rest of the image to stretch for 420 meters (the length of 14 blue whales) to fit the rest of the Solar System in accurately. At this scale, Earth would be the size of a grain of sand.
Of course, our Sun is way bigger than 10cm. It’s so huge, that you could fit Earth into it 1 million times. The real distance from the Sun to the Kuiper Belt (a region of icy comets beyond Neptune, the last planet in our solar system, where poor old ex-planet Pluto resides) is almost 6 billion kilometres.
Already we look completely insignificant. And we’re just getting started.
In 1977, NASA launched a space probe named Voyager 1. 35 years later, back in 2012, Voyager 1 became the first ever man-made object to enter Interstellar Space, travelling at an average speed of 17 kilometers per second.
This is impressive, but let’s not get too excited with ourselves. What Voyager 1 has done so far is to escape the heliosphere; a kind of bubble maintained by plasma from our Sun, that contains all the planets of our Solar System and shields us against the atmosphere of Interstellar Space.
But before it truly escapes the Solar System, Voyager 1 will have to make its way through the Oort Cloud.
The Oort Cloud is a monster; a spherical shell of icy objects surrounding our heliosphere, that extends for one-quarter of the way to the nearest star. This insanely large cloud is the origin of many of the comets that we observe today.
On his blog Wait But Why, Tim Urban put the Oort Cloud into perspective like this;
‘If the solar system [the heliosphere part] is a penny, the Oort cloud is a sphere that starts 30cm away from the penny and extends 30 meters in all directions.’
Voyager 1 will have to travel another 300 years just to get to the beginning of the Oort Cloud. After that, it will take a further 30,000 years to make its way through. Then, finally, in around 32,315 AD, Voyager 1 will have truly left our Solar System for good.
One more gift from Voyager 1: back in 1990, it took a famous photograph that you may have seen. After it had passed the last planet in our Solar System, astronomer Carl Sagan requested that it be turned back towards Earth to take a photograph. It captured something beautiful that puts our existence in perspective like nothing else: planet Earth is the size of a tiny pixel, hanging in a beam of sunlight.
The photo was named Pale Blue Dot, and it looks like this:
See that tiny blue speck in the beam of light about half-way down?
‘Look again at that dot. That’s here. That’s home. That’s us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every “superstar,” every “supreme leader,” every saint and sinner in the history of our species lived there – on a mote of dust suspended in a sunbeam.’ – Carl Sagan, ‘Pale Blue Dot’
As small as Earth already is, and as vast as the Oort Cloud appears to us, we’ve got a long way to go. We’ve not even left our home galaxy yet.
If the Solar System is our house address, then the Milky Way galaxy is our city.
Our next door neighbour in this city is a three-star system named Alpha Centauri; the closest of the three, Proxima Centauri, is approximately 4.22 light-years away (so it takes light 4.22 years to travel to Earth from that star). Here’s a photo, taken once again by the Hubble Space Telescope:
At its current speed of 60,000 km/h, Voyager 1 would take 76,000 years to arrive at Proxima Centauri. If our sun was the size of a penny, then Proxima Centauri would be 350 miles away.
In other words, it’s a long way from us.
But travelling 4.22 light years is like taking a step out of your front door in galactic terms. Let’s expand our reach to 250 light years away from Earth. How many stars would we find in this range?
Which seems like a lot, until I tell you that our Milky Way galaxy measures 100,000 light-years from end to end and contains between 100 and 400 billion stars. Our Sun is just one star among a vast ocean of stars that make up our home galaxy.
This map of the Milky Way shows where our Sun is located in relation to the rest of the galaxy (in the centre, about two-thirds down):
The Earth is invisible at this scale, but at least you can vaguely locate us by spotting our star. Don’t get too attached to that fact though, because it won’t last long.
To try and put our galaxy in perspective, let’s use the penny and the grain of sand again;
If our Sun was the size of a penny, the Milky Way Galaxy would measure 7.5 million miles across.
Well, if our entire solar system was the size of a grain of sand, then the Milky Way would be the size of 1,000 cathedrals.
If you still find that hard to grasp, you’re beginning to realise what I meant about how incredibly difficult it is to put space into perspective, even in comparison to time. And the Milky Way galaxy isn’t even one of the giants. For example, let me introduce you to M87, a galaxy with a diameter of 980,000 light years:
Yep, light takes almost a million years to cross that bright circle in the middle of the picture. Insane.
But let’s not get ahead of ourselves.
Galaxies tend to cluster together into groups. Our Milky Way galaxy is part of the Local Group, which contains 54 galaxies within a diameter of 10 million light years (100 times the length of our galaxy). If the Milky Way is our city, then the Local Group is our county, state, or region.
One of my favourite galaxies in the local group is the Large Magellanic Cloud (200,000 light-years from Earth) where new stars are being born as vast clouds of gas slowly collapse. This is a science-y way of saying that it makes for incredible photos:
Another pretty awesome/scary-perspective-gaining thing I found from our Local Group is called Smith’s Cloud. This is basically a super-fast, super-huge cloud of hydrogen gas headed straight for the Milky Way Galaxy, and it looks like this:
Image Credit: NRAO / AUI / NSF
That smear of colour is a gas cloud measuring 9,800 light years in length; in other words, one-tenth of the length of our Milky Way Galaxy. Don’t lose sleep over it though; it’s headed towards us at 300 kilometers per second, but it still won’t arrive for 27 million years. And when it does, it will just give our galaxy more material for birthing new stars, so yay for that.
SERIOUSLY HUGE THINGS
Let’s zoom out again. Our Local Group is only a small part of the Virgo Supercluster.
A supercluster is a large collection of smaller galaxy groups like our own, and one of the largest known structures in the entire Universe.
The Virgo Supercluster itself:
– measures around 100 million light-years across
– contains 200 different galaxy groups
– with thousands of individual galaxies
– and a total of 200 trillion stars
Our Milky Way galaxy is just a tiny speck of light in the vast space of the Virgo Supercluster.
In 2014, scientists realised that the whole Virgo Supercluster was itself just an appendage of another, much bigger supercluster, known as Laniakea (a Hawaiian word meaning ‘immense heaven’). This beast measures 520 million light-years across, and contains about 100,000 times the mass of our entire Milky Way galaxy. Our Local Group is just a tiny county or state in the huge country that is Laniakea.
The picture below is a map of Laniakea, and the blue dot with the red arrow coming out of it represents the location of our galaxy:
I’m starting to get dizzy (maybe I shouldn’t be studying the size of the Universe this late at night).
Let’s zoom out yet again.
Here’s a map of our neighbouring superclusters, around 1 billion lightyears away from us in each direction (as Lanikea is a new discovery, this map doesn’t include it; so look for the Virgo Supercluster near the centre instead):
I had one reaction when I saw this map: oh, shit.
I think this is where it finally sunk in for me. We can barely see our own local group of galaxies on this scale. There are one hundred superclusters in this amount of space, 240,000 galaxy groups, 3 million large galaxies and 250,000 trillion stars. Remember how we started this section? The observable Universe is 93 billion light years in diameter. Which means that this whole map is just a tiny percentage of what we can see.
And just look at those voids. A void is a huge section of space with almost no galaxies in it. Basically, there’s nothing there. The one to the left of us on the map, the ’Sculptor Void’, measures 275 million light years in diameter. That is a whole lot of nothing.
The slightly scary fact is that most of our Universe is empty (there may be the odd particle, and of course we could mention dark matter, but that’s a topic for another issue). Actually, something like 99.9999999999999999999958% of our known Universe is basically nothing; and even with that fact, our sky is full of stars in every direction. This should tell you something of the vast numbers we’re dealing with.
THE BIGGEST THING
OK, so let’s zoom out one more time.
The entire Observable Universe, as we’ve already said, is 93 billion light years across and contains 1 septillion stars. If you make the whole Universe the size of a cathedral, our Milky Way would be one grain of sand.
Once you get to this level, things get incredibly complicated and difficult to comprehend. You start hearing words like voids, nodes, walls and filaments used to describe collections of superclusters and the empty space in-between, and you end up with pictures like this:
I can’t even begin to understand or put words to what’s going on in that picture. Language (for me at least) has come to an end. All I can do is gawp at my computer screen and feel like my brain just melted.
As I researched this issue, I planned to include a little bit about multiverse theory; but I really can’t. Our observable Universe is mind-blowing enough without considering the possibility of infinite space beyond it.
Instead we’ll stop here for the sake of my sanity, and take a second to zoom back in:
There we all are, living on that tiny grain of sand flying through vast swathes of emptiness at incredible speed, infinitesimally tiny and far removed from even our closest neighbours.
And do you want to know the size of the Earth in comparison to the whole observable Universe?
It’s the same as comparing the size of a virus to our whole solar system.
Do you feel small yet?
Actually, I’d like to make you feel slightly smaller (nothing personal).
In the history of Earth, there have been approximately 108 billion humans. If you are reading this, you are one of them: congratulations! But do you know how big that number actually is?
To help you out, I drew a picture of what 1 billion people looks like :
That picture represents almost all of the people who currently live in the USA and Europe combined. Now imagine that picture repeated 108 times, and you have every human being who ever lived.
Every celebrity, every historical figure, and every world leader is just one tiny dot among those billions. The vast majority of those dots have been forgotten. And of course, one of those tiny dots represents you.
108 billion dots, each with their own ideas about life, the world, the gods, death, sex, work, purpose.
How many religions and beliefs have existed during those 108 billion lives? This chart lists 30 major religions that exist in the world today. This page on good old Wikipedia opens things up a bit, and there’s already too many to count. Imagine all the denominations, sects, cults and tribes that we’ve never even heard about from the last 200,000(ish) years. It’s a massive number.
I’m not just talking about spiritual beliefs though. I’m talking about scientific theories, political leanings, personal philosophies and all kinds of ideas that humans have. How many of those 108 billion dots lived their entire lives convinced that their ideas were right? How many of them laughed at the beliefs of their enemies, confident that truth was on their side?
It’s impossible to know how many varieties of belief have ever existed, but one thing I could confidently say: no two people think exactly the same on everything. In that sense, it wouldn’t be completely ridiculous to suggest that 108 billion different worldviews have existed on planet Earth.
I don’t know about you, but all of this makes me question my own ideas. For example, I grew up with Christianity, which is why it’s the religion I talk about the most on this site. It’s one of the big religions, with around 2 billion people who identify as Christians today. But Christianity has only existed for 1% of the time that humans have walked on Earth, and most of those 108 billion dots have never even heard of Jesus Christ (one of the reasons that I struggled with the idea of Hell).
Which means that now some of my most closely held and personal beliefs are being put starkly into perspective.
So, where does this all leave me?
Which leads me to a couple of important final thoughts.
Firstly, it leads me to humility.
I love faith and mystery and spirituality. I really do. Even though I freaking love science, I also believe in things that I can never prove or convince another person of. I have experiences where I feel connected to something greater, and moments where I am aware that I feel close to God (whatever that means).
But I have grown allergic to certainty. I know that my spiritual experiences and beliefs could be an illusion created by my own brain, or just plain wrong. And I’m totally OK with that. I’m just one dot after all, with my own blind spots and biases and errors in thinking.
I grew up in an environment where we had all the answers. The truth belonged to us, and there was a world outside our boundaries that desperately needed to hear that truth for themselves. There was no suggestion that we could actually learn something from those other people. They were supposed to learn from us. The only source of final Truth for us was the Bible.
But when we put the Universe in perspective, we begin to realise that it’s crazy to think that any one group of people has the monopoly on truth. And honestly, it’s also boring; if we know everything, what’s left to learn?
Humility is knowing that we don’t know. It’s accepting our uncertainty as something to embrace and enjoy, and asking what we can learn from the experiences, ideas, and beliefs of other people, instead of telling them what to learn from us.
Secondly, it leads me to awe.
As I put time and space and my tiny existence into perspective, I could get depressed about it. What does my life really mean in the grand scheme of things?
But I don’t feel that way.
Instead, I’m even more aware of how insanely unlikely and incredible it is that I’m alive in the first place. What are the chances?
Even if you take the biggest things for granted, for example the chances of our galaxy forming and life evolving on Earth, and just calculate the odds of your parents meeting and making you, this great infographic declares that your chances are 1 in 102,685,000 (that’s a 10 with 2,685,000 zero’s after it).
That just makes me incredibly grateful to be alive, and more determined to make the best out of the short time that I have.
It also makes me value life all the more. There’s over 7 billion dots alive on our grain of sand right now, and a bigger perspective makes our boundaries and differences and tribal behaviour seem insignificant, pathetic, and kind of dumb. If our chances of being here are so small, and if everything is so temporary, it makes sense to look after what we’ve got and not treat everything like it’s going to be around forever. It makes sense to think about issues like global warming, the use of natural resources, and even space travel. It makes sense to work on unity and respecting each other.
Finally, when I gain a greater perspective I feel completely amazed and in wonder at the Universe that we call home. It’s beyond the ability of my brain to comprehend. It’s literally impossible for me to fully grasp the world I live in. I just find myself way more hungry to learn and explore and discover new ways of seeing.
And if that isn’t a spiritual experience, I don’t know what is.
Comments : The Allowed is a safe space for people of all backgrounds who are wrestling with faith and doubt; many of whom may have had negative or traumatic religious experiences. Please be respectful and kind in any comments you make.