Do you ever feel like you are getting lost in the details? Like life is getting out of control and you cannot see the wood for the trees? Do you ever worry you are losing perspective? It happens to all of us from time to time, the little details mean we lose sight of the bigger picture, and things can become overwhelming.
Firstly, and most importantly, don’t panic.
Secondly, and not in any way as important as the first point (perspective!) you are reading just the right blog post at just the right time. This post is about perspective, or at least trying to put some perspective on the enormity of the universe and our little lives within it.
As a young child to think of the biggest number they can, and they might say one hundred, or maybe a thousand. As they get older they may choose one million, or even learn about billions and trillions. Eventually, the child will learn about infinity, the biggest ‘number’, and will use this to end a competition to think of the biggest number. That is of course until their friend says infinity plus one and then the battle continues with ever increasing infinities (incidentally, having different infinities is not as daft an idea as it may first appear).
I would imaging most of you reading this post will have moved on from competitions to name huge numbers. I would also imagine only a few of you have ever sat down to think about just how large some of these numbers can be, and when it comes to the rest of this post, understanding large numbers is going to be useful.
For most people, the number 10 is going to be an easy concept to grasp. Most of us have ten fingers, and you can probably imagine a collection of ten objects fairly easily. Similarly, you can probably grasp the idea of 100, find a large room and you could fit 100 people in it. Even 1000 is a fairly easy idea to get your head around.
Start to get to numbers bigger than 1000, and some people might start to find the numbers blurring a little. When you are at figures like a million or a billion, and for many people there can appear little difference between the two. I am sure news reports about millionaires and billionaires make the difference appear small, but the difference between the numbers is stark, and can be best demonstrated thinking for a moment about a million and a billion seconds.
A million seconds probably seems like a long time, and it is. It is just over 11 days. Every 11 days or so a million seconds has passed.
So how about a billion seconds? A month maybe? Maybe a year? No, a billion seconds is nearly 32 years.
If you think about it, the difference is obvious. One billion is a thousand times bigger than one million. But written as million and billion the difference is not clear. The difference between 11 days and 32 years however… Put another way, 11 days is roughly how long an Olympic Games lasts, whereas 32 years ago was when the Seoul Okympics was held, shortly after I was born.
You might be thinking at this point your perspective on the world is unchanged, but hold that thought for a moment. It is important to grasp the idea of and difference between big numbers, as we are about to see some truly massive numbers.
At the time of writing this, the universe is 13.8billion years old, give or take a century or two. That is a vast quantity of time, beyond I suspect anyone’s ability to fully comprehend. If you live to be 80 years old, you could have lived 172.5million times back to back since the beginning of the universe, which is still a ridiculous number to try and understand.
For the first 380,000 years of the Universe it was so hot atoms could not exist and space was opaque. The earliest detectable observation of the Universe, the Cosmic Microwave Background, occurs at this time, and can still be detected today by satellites (or a badly tuned TV in the form of static).
Then for the next 9.5billion years, the Universe is awash with the formation, life and death of stars and planets, countless numbers which have come and gone until 4.5billion years ago (still a stupidly long period of time, or 56.25million lifetimes back to back), a small insignificant star formed at the edge of an ordinary galaxy.
Today, we call that star the Sun, and in the left over debris disc at around the same time, 8 planets and a collection of minor planets, asteroids and comets form. The third planet from the Sun we now call Earth, and one day it would be the place we call home.
But we are not quite there yet in time. For roughly the first quarter of a billion years, Earth was a lifeless, molten rock. But it quickly cooled, oceans formed, and around 4.28billion years ago, for possibly the first and only time, life began.
Single cellular life for around a billion years, before multicellular life evolved a couple of times around 3billion years or so ago. And the evolution of life does not stop there, with more and more complex animals evolving, living, dying and for the most part going extinct again.
By the time we are into the millions rather than billions of years ago, some of the more familiar life begins to evolve. Dinosaurs appear 230million years ago, before a wayward asteroid 66million years ago sees them bite the dust as well (at least the non-avian dinosaurs, after all we still have birds). And as a quick aside, the dinosaurs roamed the planet for such a long period of time that we find ourselves closer in time to the dinosaurs killed by the asteroid than those dinosaurs were to the first dinosaurs to evolve.
After dinosaurs came the age of mammals, until as early as 300,000 years ago (coincidentally a similar length of time from the start of the universe to the formation of particles) a bipedal hairless ape begins to differentiate itself from other species, making ever more complex tools, developing language and eventually the ability to examine the Universe in such detail as to allow me to write this post in the first place.
If the entire history of the Universe, all of time, is consider a single year, with the Big Bang happening on 1st January, then the Earth formed some time around the 2nd September, life came into existence on the 14th September, dinosaurs came and went between the 24th and 26th December, modern humans began using tools at around a quarter to midnight on the 31st December, and the entirety of what we consider history takes place in the final second before midnight. The history of the Universe is vast, and even condensed into a single year it is still difficult to comprehend just how big it is.
And after thinking about the past, it is worth considering the future as well. If the Universe is anything, it is dynamic, and it certainly will continue to change and expand. While predicting the future is a fool’s game, there are some things we can be sure of with a pretty good degree of certainty.
For example, in around 5 billion years, or just a little longer than the Sun has existed already, it will run out of hydrogen, the fuel from which sunlight is created. As it runs out of fuel, the Sun will begin to expand, becoming a red giant star. And in the process, it will engulf Mercury, Venus and probably the Earth, but even if the Earth survives it will be uninhabitable. So assuming life survives long enough and our descendants do not leave Earth and travel into space, life on Earth has at the very most 5 billion years left. Given we have already had over 4 billion years for life so far, the half way point is only a few hundred million years away.
Fast forward to 100 billion years, over seven times as long as the Universe has existed to date, and the galaxies outside the Milky Way will have travelled so far away from us they are no longer visible as light cannot reach us. And then in as little as 1 trillion years, the formation of new stars may well cease as the gas and dust from which they form are depleted. From here, it is all downhill, with the eventual outcome, according to one theory I tend to ascribe to, is the heat death of the Universe, where nothing but a vacuum remains. But don’t worry, this outcome is so far in the future I have not even attempted to estimate it. It is certainly not worth making big life decisions on the possibility of a Universal end.
The average human walks at around 5km/h. Walking at that speed, it would take around 55 hours for me to walk without a break from my home in Leeds to the centre of London.
At the same speed, it would take about 1250 hours, or around 52 days to walk the full length of the wall-section of the Great Wall of China.
On a human scale, the world is huge, and even the advent of cars, trains and planes has done little to shrink our planet. If we were to walk the full circumference of the planet (assuming of course we could walk on water) it would take nearly a year of constant walking without breaks or sleep to cover the distance. Even driving a car at 120km/h, it would take a fortnight of constant driving to finish the trip.
Moving out from the Earth, the next lump of rock you will come across is the moon, to date the furthest from Earth any human has been. The moon orbits between 360-400,000km from Earth, so at walking speed it would take us at least 72,000 hours or 3000 days or just over 8 years of constant walking to cover the distance, assuming you could hold your breath of course.
Once you pass the moon, it becomes unwieldy to keep thinking of distances in terms of walking speed. The distance to the Sun alone is so vast it takes light (travelling at the cosmic speed limit of 300,000km every second, or put another way a trip to the moon in just a second) around 8 minutes to cover the distance. This is a huge distance.
From the Sun, the next nearest star to us is the Alpha Centuri system. By this point there is little use thinking in terms of kilometres, or the distance light travels in a second. Instead, we need to think of the distance light can travel in years, the light year (ly). In this case, it is just over 4ly to Alpha Centuri, which also means when we look at the star (actually stars, but that is beyond this post) on Earth, we are actually looking back at the star in time. It has take over 4 years for the light to reach us, we see the star as it appeared 4 years ago. It might not be possible to travel through time, but we can certainly look back in the past.
Our planet, the Sun and Alpha Centuri all occupy one small part of the Milky Way Galaxy. A spinning disk of at least 250 billion stars (back to the huge numbers) the Milky Way is around 200,000ly across. Think about that. It takes light, the fastest thing in the Universe, 200,000 years to cross from one end to the other. In the time the entirety of human history has taken place, light from the far ends of the galaxy has only just completed its journey to the far side.
And we are only just getting started. Because the Milky Way is only one of potentially more than 2 trillion (yes trillion, as in a 2 with 12 zeros after it) galaxies in the observable Universe (more on that in a moment). Our nearest neighbour galaxy is called Andromeda. Roughly the same size as the Milky Way, it is moving towards our galaxy at an incredible rate, but even so it remains 2.5 million ly from the Milky Way. Light from Andromeda left the galaxy long before human ancestors had even contemplated leaving Africa. And when I say Andromeda is moving towards us at a rapid rate, it will still take it 4.5 billion years (or as long as the Earth has already existed) before the galaxies meet. The space between them is just vast.
In the last paragraph I mentioned the observable Universe, and it is here we find another order of magnitude in size. Given light has a finite speed limit (albeit an enormous limit) and the Universe has existed for a finite amount of time, only light within a certain distance of earth has had sufficient time to reach us since time itself began. This gives rise to the observable Universe. While the Universe might well be infinite, there is only a set amount of space we can observe, and we call it the observable Universe.
As you would imagine, the distance across the observable Universe is epic beyond imagining. At 93 billion (!) light years, the distance from one side of the observable Universe to the other is beyond comprehension. It would take light over six times the entire history of the Universe to cross the distance, and given space is expanding by the time it got there is would have further to travel anyway.
This is an enormous space, and despite having 2 trillion galaxies within it, it is mostly empty space. Set off in a space ship in a random direction, and chances are you could travel until the end of the Universe and never reach another star or galaxy. Space is vast, and space is mostly empty, but that’s OK, chances are we as a species will never travel beyond our local area, if at all.
In the 4 billion or so years since life began, Planet Earth has been well and truly over run. From what would have been simple, single cells to the multitude of animals, planets and other life we see today. Just considering how elephants, dandelions, mushrooms and bacteria all have the same common ancestor is mind-bending.
It is estimated that around 8.7 million species of life exist today, and that does not even include the massive numbers of bacteria. While it is not the largest number we have seen in this post, it will seem larger when you realise only about 1.2 million species have actually been discovered and described by scientists. To estimate how many different species have existed through the history of life is more of a challenge, and is nothing but a ball park, but it could be as much as 4 billion species, roughly one species for every year the Earth has existed.
The numbers above are for species, what about individual organisms? How many of them exist on Earth at this moment, or have ever existed. The short answer, no one knows. It is likely the number is so large it is meaningless to estimate it. Life is everywhere, and in ever greater numbers.
One number which can be estimated, is the number of species going extinct each year, 100,000, on average one species every five minutes. Worse still, the rate is accelerating, so more and more species are going extinct each year. The cause of the acceleration, unfortunately, is us. And it is human beings we turn to for our final source of perspective.
It will probably come as no surprise there are over 7 billion people* alive on Earth today, with over 2 billion people in China and India alone. The number is rising rapidly (though it is unlikely to keep rising forever); in the 32 years since I was born the population of the world has grown from around 5 billion.
But just how large a population is 7 billion people? Imagine for a moment you wished to shake every single person’s hand (of course in the current pandemic this would be extremely foolish, but think instead of happier times). Imagine also that the population of the world stays exactly the same, with no one being born or dying, and assume a hand shake takes just 1 second.
Under these assumptions, just how long would it take to shake everyone’s hand? Well that number is over 116 million minutes, nearly 2 million hours, over 81,000 days, quite nearly a total of 222 years. 222 years of constant handshaking to greet every person alive today. 222 years to meet everyone, but not even begin to get to know them.
We are living on a planet which resides in a Universe of extremes, and even when our world and our problems can seem overwhelming, it is worth trying to keep things in at least a little bit of perspective.
*Hello from 2023 Jamie. It’s 8 billion now…
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