Welcome… to the universe.
It’s 13.8 billion years old and the observable part is 46 billion lightyears in any one direction.
With one lightyear equalling about 5.88 trillion miles, it’s incomprehensibly vast.
So, how long would it take to see it all?
This is Unveiled, and today we’re answering the extraordinary question; how long would
it take to travel the universe?
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The sheer size of the universe is one thing, but the other massive, probably unscalable
barrier preventing us from ever traveling it in the real world… is the cosmic speed
limit.
The speed of light through a vacuum.
That most famous of universal constants, the speed of light is a blazing 186,000 miles
per second.
It’s the reason why we see the universe as we do, because that’s how much light
has managed to reach us in the time since it all began.
If, then, we ever devised a way to travel at the speed of light, then the simplest answer
to today’s question is that it would take 46 billion years to move across the entire
cosmos.
Or, to travel to the edge of the observable universe from our current vantage point, at
least.
It would take roughly 93 billion years to travel across the entire map of the universe
as we currently see it.
And, because some estimates on the size of the unobservable universe exceed twenty trillion
lightyears, it would take us upwards of twenty trillion years to see it all.
Even at speed-of-light-speeds.
But humans only live for about seventy years on average… so that’s just not good enough.
To put into context what an incredible undertaking it would be to travel the length and breadth
of the universe… we can zoom in on just the Milky Way.
The Milky Way is an average-sized spiral galaxy and Earth sits at a comfortable 25,000 lightyears
away from its galactic centre.
In total, our galaxy is between 100,000 and 200,000 lightyears across, and it contains
billions upon billions of stars.
We can say, then, that at the speed of light, a journey across the Milky Way would take
up to 200,000 years.
To get to just the galactic centre, it would take 25,000 years.
But, in reality, we can’t travel at the speed of light yet, nor get even remotely
close to it.
And many predict that we’ll never be able to.
So, let’s scale it back to something we can do.
Let’s get into an average car travelling at sixty miles-per-hour with unlimited fuel…
aaand let’s imagine that the car flies.
Now, to travel the Milky Way, to travel just one average-sized galaxy in a universe hosting
billions of other galaxies, it would take more than two trillion years to complete the
trip.
That’s a journey time around 160 times longer than the age of the universe itself.
While estimates on how long the universe will last do vary, we can say that it may well
have died by the time you complete your trip across just one single galaxy.
The distances we’re dealing with here are simply massive.
So now let’s move from galaxy to galaxy.
Even without making pit stops to explore any specific stars or planets (of which there
are, again, countless billions) our journey gets longer and longer.
It’s usually cited that Andromeda is the closest galaxy to Earth, but this is true
and not true.
Andromeda is the closest large spiral galaxy to us at about 2.5 million lightyears away.
It’s also one of the largest galaxies in what’s known as the Local Group… but there
are actually 85 other galaxies closer to the Milky Way than Andromeda is.
The closest of all is Canis Major, a dwarf galaxy that’s only another 25,000 lightyears
away.
That’s only about 250 billion more years to spend in our 60 mile-per-hour car.
It’s abundantly clear, then, that ordinary propulsion systems won’t get us anywhere.
We need a better way to see everything the universe has to offer.
We need to develop a warp drive.
A warp drive, faster-than-light drive, or Alcubierre drive provides a way to travel
between stars and galaxies without the immense journey time.
And the good news is that most interpretations of Albert Einstein’s theories, and of the
laws of physics in general, do allow for warp drives to be possible... which is one reason
why they’re so popular in science fiction.
If we built one according to Alcubierre drive designs, it would work by creating a bubble
of space-time to shield a spacecraft, “warping” everything ahead of the ship to make the distance
it travels physically smaller.
All of which means that, in theory, you would get to your destination faster than lightspeed,
despite the speed of light never being broken within your immediate bubble.
And the laws of physics remain blissfully intact.
But warp drives do present problems.
Chief among them is that although they may be technically possible, we still don’t
actually know how to build one… and we also don’t know how we’d power one.
Significantly bending space-time is something only the most massive objects in the universe,
like black holes, are capable of.
But, for a warp drive to work, we’d need similar capabilities in one single machine.
As such, proposed warp drive models usually require exotic matter to fuel them - with
exotic matter being, quite inconveniently, a new state or type of matter unlike anything
we’ve already observed.
So, the disappointing reality is that to get a warp drive to go we’ll need something
that doesn’t exist yet.
With a warp drive, travelling the universe could conceivably be done within a manageable
timeframe even by human standards.
Without one, we’re back at countless lifetimes just to reach a nearby galaxy.
In one other sci-fi pipe dream solution, we could first find a way to travel backwards
in time, zap ourselves to a moment just after the Big Bang (before the universe had expanded
to the size of today), and the distance required to travel the whole thing would be so much
smaller… buuut that’s just an awful lot of probably impossible work, and enough to
make even the discovery of warp drive-enabling exotic matter seem more likely by comparison.
Say all of the problems were solved and you did, in some future time, have a warp drive,
however.
What are you going to see outside the windows as you hurtle through space?
Perhaps, because of the immense speed you’d be travelling at, you wouldn’t see much
of anything.
You’d be covering more than seven times the circumference of Earth every single second.
At least.
In fact, for safety reasons, your ship probably wouldn’t have windows at all.
It highlights one of the more unfortunate aspects of space travel, even just within
our relatively tiny solar system.
So much of it is either moving slowly through darkness for multiple generations… or moving
incredibly quickly, and too fast to witness anything of your journey.
Because the distances are so massive, and because it’s been calculated that 99.99%
of everything in the universe is simply empty space, the travel itself is long and lonely.
Today we sit somewhere in the middle of the two modes of transport we’ve spoken about.
Somewhere between our traditional 60 mile-per-hour car and a futuristic warp drive.
But we’re still much, much closer to the car.
The fastest any human has ever travelled was on the return leg of the Apollo 10 mission,
when the three astronauts were at one stage propelled back towards Earth at 24,791 miles
per hour.
No doubt this was an impressive feat, but there’s still a monumental jump between
Apollo 10 and the speed of light.
More recently, NASA’s space shuttles could hit slightly lower top speeds of close to
18,000 miles per hour.
Say, then, that we had a way of maintaining this speed indefinitely.
Which we don’t… but let’s imagine.
If you flew a shuttle as fast as it could go then you would cover the distance of just
one light year… in about 37,000 regular years.
You’d have to do that journey more than 200,000 times to reach the next closest galaxy
to us.
And more than 46 billion times to reach the edge of the observable universe as it currently
stands.
But, by that point, the edge of the universe will have expanded outwards further still…
leaving you more and more distance left to travel.
At space shuttle speeds, you’d be forever chasing that elusive outer boundary.
And, for as long as the universe continues to expand, you’ll have an infinite journey
on your hands.
Even at the speed of light, it figures that you’ll always be 46 billion years away from
the finish line.
Until, at a time literally trillions of years in the future, you may have finally scaled
all of the unobservable universe, as well.
And that’s how long it would take to travel the universe.
What do you think?
Is there anything we missed?
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