Welcome to life on Earth, in the solar system, in the Milky Way… in the universe! Thanks to
years of scientific and astronomical progress, today we’re reasonably confident with what the
physical structure of our reality looks like. There are maps of the universe to guide us,
and we have telescopes pointed all over space trying to better our knowledge even more.
All in all, it’s quite something to comprehend. The scale is already mind-blowing. But what’s
truly difficult to fathom is that it’s all also shifting forever before our very eyes.
So, this is Unveiled, and today we’re exploring the extraordinary claim
that scientists know the universe is disappearing… and there’s nothing we can do about it.
Do you need the big questions answered? Are you constantly curious? Then why not subscribe to
Unveiled for more clips like this one? And ring the bell for more thought-provoking content!
Had you been alive some 13.8 billion years ago, then not only would your existence have been
even more of a miracle than it already is… but you’d have been there to witness the beginning
of all things. The Big Bang, as per the most widely accepted model, out of which
all matter and energy spread in all directions, to bring the universe into existence.
Various scientists and theories claim to have tracked time back to within just the first
few moments after the Big Bang… but, so far, we remain fairly oblivious as to what was happening
before it. What was there before there was everything? How did something
come from nothing? These are deep ponderings at the heart of scientific study.
But, as well as being hung up on how we came to be, there’s also the question of what will become
of us? Where is all this heading? If you were the universe, what would your end game look like? For
this reason, astronomers are constantly peering as far out into space as they possibly can, in search
of answers. But ultimately, it appears, their time for finding answers is actually running out…
because the universe, it seems, is disappearing. The primary reason for this is universal expansion
and the fact that it’s accelerating. We’ve known for decades that the universe is expanding,
and that stars, planets and galaxies that aren’t in our local group (and therefore held by gravity)
are always moving away from us. We’ve also known since the late twentieth century that the
rate of that expansion is accelerating, which means that more stars, planets, and galaxies
are moving away from us with every passing second. In the time it takes for you to watch this video,
thousands more cosmic objects will’ve moved thousands of miles further away.
Scientists believe that the ultimate result of this is that one day, in the far future,
and if accelerating expansion continues, our local group of galaxies
(including the Milky Way and Andromeda) should find itself totally isolated from all other
galaxy groups. We should eventually be not so much cut adrift as stretched adrift from all the
rest of space, with far darker skies set against an ever-deepening void. But how does that work?
Really, the key thing that’s happening here is that the universe expands at faster than
the speed of light. You might reasonably ask; how is that possible? We know that a
cornerstone of all physics is that nothing can move faster than lightspeed. That lightspeed
works like an ultimate speed limit for all objects in the universe, from planets to particles.
And yet, scientists are also well aware that stars are moving away from us at faster than that rate.
Or at least they seem to be. And that’s because there’s a crucial,
extra consideration to factor in… that while the speed of light still applies to all objects in
space, it doesn’t apply to the expansion of that space. Space itself expands effectively
faster than light, so that it appears as though objects within it also move faster away from us.
The most commonly used visualizations of this include imagining galaxies as though they’re
raisins in bread that’s rising, or ants on a beach ball that’s inflating. The raisins (or
ants) don’t have to move themselves, but they can still appear to be moving, regardless.
This means that when we study the universe there’s also a kind of outer boundary that cuts through
it, beyond which we’re genuinely losing touch with stars and galaxies forever.
As entities of physical matter, the fastest we ourselves could ever hope to travel in one
direction is still lightspeed… but even that isn’t enough when set against the boundless backdrop of
universal expansion. Even the universe, then, as vast, magnificent, and all-encompassing as it is,
won’t last forever from our point of view. At this very moment, there will be parts of it that
have just slipped away from us - a few stars, or a couple planets, perhaps - never to be seen again,
no matter how advanced our technology becomes. From our perspective, an endless stream of objects
is continually moving to that point beyond which we’ll ever be able to retrieve them. And it will
continue in this way unless the fundamental rules change. Unless expansion slows or stops,
for example, or unless universal contraction takes over. The current
endpoint is quite straightforward to imagine, then, even if it’s also desperately lonely.
But still, that endpoint (as lonely as it is) won’t likely take hold until billions (perhaps
even trillions) of years into the future. Seeing as Earth itself might only survive for another
five billion years or so, at which point the Red Giant sun may well
consume it… what does it really matter to us? Well, naturally, we find ourselves experiencing
just one part of the journey. And, while it might seem a little dramatic to claim that the stars are
going out… it is true, to some degree. Again, whenever we look out into the universe,
what we’re also seeing is cosmic matter (stars, planets, dust, and objects) that’s continually
moving beyond our reach. So, we can also say that in the time it takes to watch this video,
not only will thousands of objects have moved thousands of miles further away… but many of
them really will have disappeared forever, as well. And that’s surely pretty significant?
There’s now just a little less of the universe available to us than there was before... and
that’s happening everyday, all the time. Perhaps it’s a part of life that’s also a little
bleak… but there’s no need to panic just yet. As with most of the big questions about the universe,
the reality is somewhat softened by the fact that it’s still massive. It has been estimated
that there are around two trillion galaxies out there, in total. And although it’s also
been said that only around five percent of that two trillion are still accessible to us (that is,
they still fall within the confines of lightspeed) we’re still talking billions of galaxies, hosting
billions of stars and planets, that are still within the realms of physical possibility from our
point of view. There’s still so much cosmic matter out there that we can try our best to explore.
So, it’s not as though all is lost. But what’s your take on the matter? Does a
disappearing universe frighten you? Or perhaps it inspires you to learn more about everything
that is still reachable for us? Of course, there might yet be some sci-fi style innovations that
one day provide a solution for all of this. The peculiar physics of wormholes, for example,
might enable travelers to skip all physical restraints, to punch holes through the cosmos,
and to emerge out the other end into galaxies that had previously disappeared from view. But, in
reality, we’re still very far away from wormholes being anything other than a theoretical concept.
Perhaps it’s worth considering, though, the next time you look up into the night
sky. What you’re gazing into really does go on forever… but, also, what you can ever see of it
will always be limited. And, for as long as universal expansion continues to accelerate, then
that limitation will inevitably take more and more of the cosmos away from us. It’s a stark truth,
a cold moment of realisation… but it’s also pretty mind-blowing, don’t you think? And that’s how
scientists know that the universe is disappearing… and there’s nothing we can do about it.
What do you think? Is there anything we missed? Let us know in the comments, check out these other
clips from Unveiled, and make sure you subscribe and ring the bell for our latest content.