Quantum processes can’t be predicted, not even in principle. Not because we are silly and don’t know
how to do it – according to quantum physics, quantum particles are intrinsically random.
For example, if you have a radioactive atom, it could decay at any moment,
in the next second or in the next million years. We can calculate the
probability that it will decay tomorrow, but no oracle in the universe will ever
be able to tell you with absolute certainty if it will do so or not.
But quantum particles can change the world.
Imagine a radioactive element randomly decays and causes a genetic mutation in a nearby mammal. And
then many generations later that mutation has led to a weird mix of duck and mammal
that makes no sense. Or the atom decays a day later and the weird creature will never exist.
If quantum stuff is really uncertain, the future can’t be set in stone. But if the
future is an untold story, it can’t be real in the same way as the past is.
So what happens when uncertain things, like the decay of our atom,
become real? Is that moment the present? Is this “now”? But before we saw that cosmic
democracy makes it impossible to define an absolute “now”. What’s going on here?
It turns out that for every individual object – you, an alien, an atom – the past,
the present and the future are always well defined. Your death will always
happen after your birth – never before, and never at the same time. Now you are clearly
between your birth and your death. So for you at least, "now" makes perfect sense.
If we don’t play tricks like going to the other side of the universe and using aliens
in funny ways to find out what “now” means, things again start to look ordered and nice,
and individual “nows” seem to exist. Can we do something with them?
Let’s return to our block universe. Maybe the block does not contain the future – and maybe
we just imagined it wrong. Maybe the block is just the past, and a thin layer on the surface is the
present. That surface is not smooth, but bumpy and uneven. It’s been made by joining countless
individual “nows” – each experienced by someone or something in the universe,
each equally real and valid. And all observers do their bit, so cosmic democracy is still true.
As new things happen and uncertain things become certain –radioactive atoms decay,
new species of mammals arise, people miss the bus– the border moves upward,
creating new time in the universe. Instead of a frozen block of time with
a future that has already been written, the block is growing and things happen.
You can again decide your future! Maybe leave earlier so you won’t miss the bus!
Let’s recap. We started with time as a movie – one “now” after another,
where only the current “now” was real. Then we found out that because of relativity there
are multiple “nows”, all of them real somehow – which could mean that we are living in a frozen
block universe where things don’t happen and you don’t really have free will. And we ended
up with a kind of growing block universe, where time passes and the future is open.
So which is correct? What is real? The present? The past? Are the dinosaurs as real as you are
right now? What do the aliens on the other corner of the universe think about all this?
To be honest, no one knows. What we’ve learned are two possibilities to describe time, but
they're not the only ones. Some scientists think that the idea of “now” only makes sense near you,
but not in the universe as a whole. Others think that time itself doesn’t even exist – that the
whole concept is an illusion of our human mind. And others think that time does exist,
but that it's not a fundamental feature of the universe – rather,
time may be something that emerges from a deeper level of reality, just like heat emerges from the
motion of individual molecules or life emerges from the interactions of lifeless proteins.
We could go on, but… aren’t you about to miss the bus?
The concept of time is abstract and elusive, possibly beyond complete
human comprehension. Fortunately, there’s a vast world of things we do understand about
the universe that you can explore right now — thanks to our friends at Brilliant.org.
Brilliant has thousands of bite-sized, hands-on lessons in science, math,
technology, and beyond. Their latest course, “Introduction to Probability,”
offers a practical guide to interpreting the world. You’ll master the tools of chance,
risk and prediction while learning to model real-world situations and running simulations
of everything from election results to who will win the next World Cup. They even have
a lesson on “The Past and Future,” where you’ll explore how past outcomes may not
reliably forecast future events in the ever-evolving tapestry of time.
And since it’s always a good time to learn we’ve created an entire series of lessons in
collaboration with Brilliant to take your scientific knowledge to the next level.
These lessons let you further explore the topics in our most popular videos,
from rabies and mammalian metabolism to climate science and supernovae.
Think of each one as an interactive, one-on-one version of a kurzgesagt video.
To get hands-on with kurzgesagt lessons and explore everything Brilliant has to offer,
you can start your free, 30-day trial by signing
up at Brilliant.org/nutshell. And for kurzgesagt viewers:
the first 200 people to use our link get 20% off an annual membership once their trial ends.
Our shop has grown so much over the years,
thanks to all of you! Now it’s time to move our precious products to a bigger warehouse!
But should our tiny birbs really have to carry all those boxes? No! Help us out
and grab a box in our biggest sale ever! But first, we'll give you a little tour:
Here you can see how our posters are actually created. And this is how our enamel pins are made.
But watch out – there are some pretty creepy and dangerous things in here as well!
And this is where the deals are crafted. They will only be available for a short time and
as long as supplies last, so head over to the shop now. The birds really appreciate your help!
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